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| 1 | ANNUAL DISTRIBUTION FEATURES OF PRECIPITATION IN CHINA AND THEIR INTERANNUAL VARIATIONS显示文摘The hierarchy and definition of the precipitation-concentration degree and precipitation-concentration period of annual precipitation have been proposed by using the so-called vectormethod of annual distribution of precipitation,so that the two relevant parameters can representthe annual distribution of total precipitation correctly and indeed accurately.The relationshipbetween the spatial and temporal distribution patterns and variations of the two parameters and theannual precipitation amount in China has been further investigated.Results demonstrate that theprecipitation-concentration degree and the precipitation-concentration period increase fromsoutheast to northwest gradually.Moreover there obviously exists a belt pattern:the largestvariability of the precipitation-concentration degree and the precipitation-concentration periodoccurs in the Yellow River Valley and the middle and lower reaches of the Yangtze River,corresponding to the significant zones in which flood and drought take place frequently.It is foundthat there exist high correlations between the precipitation-concentration degree and precipitation-concentration period and the annual precipitation amount in Northeast China,North China,themiddle and lower reaches of the Yangtze River.Furthermore,8-year and 22-year periodic oscillations in the precipitation-concentration degreeand 6-year and 12-year cycles in the precipitation-concentration period are identified by use of theirMorlet wavelet analysis. | 张录军 钱永甫 | 2003 | Acta meteorologica Sinica2003，17，2： | 112 |
| 2 | Paleostructural geomorphology of the Paleozoic central uplift belt and its constraint on the development of depositional facies in the Tarim Basin显示文摘Inclined eastward and consisting of the Hetianhe, Hetianhedong, Tazhong paleouplifts and Bachu paleoslope, the central paleouplift belt in the Tarim Basin was a large composite paleouplift and paleoslope belt with complicated palaeogeomorphic features during the Middle to early Late Ordovician. A number of paleostructural geomorphic elements have been identified in the paleouplift belt and surrounding areas, such as the high uplift belts, the faulted uplift platforms, the marginal slopes and slope break zones flanking the paleouplift belt, the surrounding shelf slopes or low relief ramps, the shelf slope break zones and deep basin plains. They exerted great influence on the development of paleogeography of the basin. The marginal slopes and slope break zones flanking the uplift belt constrained the formation and deposition of the high-energy facies including reefal and shoal deposits during the Late Ordovician, which comprise the major reservoirs of the Lower Paleozoic in the basin. Toward the end of the Ordovician, the Tazhong paleouplift hinged westward and became a westward-dipped nose as the southeastern margin of the basin was strongly compressed and uplifted. The tectono-paleogeomorphic framework of the central northern basin during the Early Silurian and the Late Devonian to Early Carboniferous changed remarkably in topography from the initial low in east and high in west to high in northeast and low in southwest. The major paleogeomorphic elements developed in these periods included the strong eroded uplift high, the uplift marginal slope, the gentle ramp of the depression margin and the depression belt. The sandstones of the lowstand and the early transgressive systems tracts were deposited along the uplift marginal slopes and the gentle ramps of the depressions comprise the prolific reservoirs in the basin. The study indicates that the distribution patterns of the unconformities within the basin are closely related to the paleogeomorphic features and evolution of the paleouplift belt. From the high uplift belt to the depression, we found the composed unconformity belts at the high uplift, the truncated and onlap triangular unconformity belts along the uplift marginal slopes, the minor angular unconformity or discontinuity belts along the transitional zones from the uplift marginal slopes to depression and the conformity belt in the central depression. The truncated and the onlap triangular unconformity belts are the favorable zones for the formation of stratigraphic trap reservoirs. | LIN ChangSong YANG HaiJun LIU JingYan PENG Li CAI ZhenZhong YANG XiaoFa YANG YongHeng | 2009 | Science China Earth Sciences2009，52，6： | 52 |
| 3 | Survey on normal distributions,central limit theorem,Brownian motion and the related stochastic calculus under sublinear expectations显示文摘This is a survey on normal distributions and the related central limit theorem under sublinear expectation.We also present Brownian motion under sublinear expectations and the related stochastic calculus of It's type.The results provide new and robust tools for the problem of probability model uncertainty arising in financial risk,statistics and other industrial problems. | PENG ShiGe Institute of Mathematics,Shandong University,Jinan 250100,China | 2009 | Science China Mathematics2009，52，7： | 54 |
| 4 | Prognostic value of red blood cell distribution width for severe acute pancreatitis显示文摘BACKGROUND Severe acute pancreatitis(SAP)is a common condition in the intensive care unit(ICU)and has a high mortality.Early evaluation of the severity and prognosis is very important for SAP therapy.Recently,red blood cell distribution(RDW)was associated with mortality of sepsis patients and could be used as a predictor of prognosis.Similarly,RDW may be associated with the prognosis of SAP patients and be used as a prognostic indicator for SAP patients.AIM To investigate the prognostic value of RDW for SAP patients.METHODS We retrospectively enrolled SAP patients admitted to the ICU of the First Affiliated Hospital of China Medical University from June 2015 to June 2017.According to the prognosis at 90 d,SAP patients were divided into a survival group and a non-survival group.RDW was extracted from a routine blood test.Demographic parameters and RDW were recorded and compared between the two groups.The receiver operator characteristic(ROC)curve was constructed and Cox regression analysis was performed to investigate the prognostic value of RDW for SAP patients.RESULTS In this retrospective cohort study,42 SAP patients were enrolled,of whom 22 survived(survival group)and 20 died(non-survival group).The baseline parameters were comparable between the two groups.The coefficient of variation of RDW(RDW-CV),standard deviation of RDW(RDW-SD),Acute Physiology and Chronic Health Evaluation II(APACHE II)score,and Sequential Organ Failure Assessment(SOFA)score were significantly higher in the non-survival group than in the survival group(P<0.05).The RDW-CV and RDW-SD were significantly correlated with the APACHE II score and SOFA score,respectively.The areas under the ROC curves(AUCs)of RDW-CV and RDW-SD were all greater than those of the APACHE II score and SOFA score,among which,the AUC of RDW-SD was the greatest.The results demonstrated that RDW had better prognostic value for predicting the mortality of SAP patients.When the RDW-SD was greater than 45.5,the sensitivity for predicting prognosis was 77.8%and the specificity was 70.8%.Both RDW-CV and RDW-SD could be used as independent risk factors to predict the mortality of SAP patients in multivariate logistic regression analysis and univariate Cox proportional hazards regression analysis,similar to the APACHE II and SOFA scores.CONCLUSION The RDW is greater in the non-surviving SAP patients than in the surviving patients.RDW is significantly correlated with the APACHE II and SOFA scores.RDW has better prognostic value for SAP patients than the APACHE II and SOFA scores and could easily be used by clinicians for the treatment of SAP patients. | Fang-Xiao Zhang Zhi-Liang Li Zhi-Dan Zhang Xiao-Chun Ma | 2019 | World Journal of Gastroenterology2019，25，32： | 50 |
| 5 | Mechanism of chain propagation for the synthesis of polyoxymethylene dimethyl ethers显示文摘Polyoxymethylene dimethyl ethers(PODE)were synthesized from the reaction of paraformaldehyde with dimethoxymethane(DMM)over different acid catalysts at different conditions.Products were found to follow the Schulz-Flory distribution law.The chain propagation proceeds through the insertion of an individual segment of CH2O one by one,while the simultaneous insertion of a few CH2O segments or their assembly is unlikely.Due to the restriction of this law,it is difficult to increase the selectivity to the desired products(e.g.,PODE3 4). | Yupei Zhao Zheng Xu Hui Chen Yuchuan Fu Jianyi Shen | 2013 | Journal of Energy Chemistry2013，22，6： | 36 |
| 6 | Red blood cell distribution width in heart failure: A narrative review显示文摘The red blood cell distribution width(RDW) is a simple, rapid, inexpensive and straightforward hematological parameter, reflecting the degree of anisocytosis in vivo. The currently available scientific evidence suggests that RDW assessment not only predicts the risk of adverse outcomes(cardiovascular and all-cause mortality, hospitalization for acute decompensation or worsened left ventricular function) in patients with acute and chronic heart failure(HF), but is also a significant and independent predictor of developing HF in patients free of this condition. Regarding the biological interplay between impaired hematopoiesis and cardiac dysfunction, many of the different conditions associated with increased heterogeneity of erythrocyte volume(i.e., ageing, inflammation, oxidative stress, nutritional deficiencies and impaired renal function), may be concomitantly present in patients with HF, whilst anisocytosis may also directly contribute to the development and worsening of HF. In conclusion, the longitudinal assessment of RDW changes over time may be considered an efficient measure to help predicting the risk of both development and progression of HF. | Giuseppe Lippi Gianni Turcato Gianfranco Cervellin Fabian Sanchis-Gomar | 2018 | World Journal of Cardiology2018，10，2： | 37 |
| 7 | Red cell distribution width to platelet ratio: New and promising prognostic marker in acute pancreatitis显示文摘AIM: To evaluate the accuracy of red cell distribution width(RDW) to platelet ratio(RPR) to predict in-hospital mortality in acute pancreatitis(AP).METHODS: Between January 2010 and June 2012, 102 patients with AP were recruited to the study. In this retrospective cohort study, for all subjects, demographic data on hospital admission, AP etiology, comorbid diseases, organ failure assessment, laboratory parameters and length of hospital stay were examined. Additionally, we used a non-invasive prediction method in addition to the RPR to evaluate the disease severity. Multivariate logistic regression analyses were used to evaluate the impact of RPR on hospital admission to predict mortality.RESULTS:The male-female ratio(59/43)was 1.37with a median age of 56.5 years(17-89 years).In both univariate and multivariate analyses,RDW and RPR were presented as independent and significant variables on admission to predict mortality.The RPR obtained on hospital admission was persistently higher amongnon-survivors than among survivors(P<0.0001).The median RPR was 0.000087 in the non-survivor group and 0.000058 in the survivor group.RPR with a cutoff value of 0.000067 presented an area under the curve of 0.783(95%CI:0.688-0.878)in receiver operating characteristic curves and could predict the mortality of approximately 80%of the patients. | Erdin etinkaya Kazim Senol Baris Saylam Mesut Tez | 2014 | World Journal of Gastroenterology2014，20，39： | 38 |
| 8 | Above-and belowground biomass in relation to envi- ronmental factors in temperate grasslands, Inner Mongolia显示文摘Above- and belowground biomasses of grasslands are important parameters for characterizing re- gional and global carbon cycles in grassland ecosystems. Compared with the relatively detailed in- formation for aboveground biomass (AGB), belowground biomass (BGB) is poorly reported at the re- gional scales. The present study, based on a total of 113 sampling sites in temperate grassland of the Inner Mongolia, investigated regional distribution patterns of AGB, BGB, vertical distribution of roots, and their relationships with environmental factors. AGB and BGB increased from the southwest to the northeast of the study region. The largest biomass occurred in meadow steppe, with mean AGB and BGB of 196.7 and 1385.2 g/m2, respectively; while the lowest biomass occurred in desert steppe, with an AGB of 56.6 g/m2 and a BGB of 301.0 g/m2. In addition, about 47% of root biomass was distributed in the top 10 cm soil. Further statistical analysis indicated that precipitation was the primary determinant factor in shaping these distribution patterns. Vertical distribution of roots was significantly affected by precipitation, while the effects of soil texture and grassland types were weak. | MA WenHong1,2, YANG YuanHe1, HE JinSheng1, ZENG Hui1,2 & FANG JingYun1 1 Department of Ecology, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China 2 School of Environment & Urban Study, Peking University Shenzhen Graduate School, Shenzhen 518055, China | 2008 | Science China(Life Sciences)2008，51，3： | 34 |
| 9 | Development and distribution of geohazards triggered by the 5.12 Wenchuan Earthquake in China显示文摘As the Wenchuan Earthquake was of high magnitude and shallow seismic focus, it caused great dam- age and serious geohazards. By the field investigation and the interpretation of remote-sensing infor- mation after the earthquake and by using means of GIS technology, the distribution of geohazards triggered by the earthquake are analyzed and the conclusions are as follows: (1) The earthquake geo- hazards showed the feature of zonal distribution along the earthquake fault zone and linear distribution along the rivers; (2) the distribution of earthquake geohazards had a marked hanging wall effect, for the development density of geohazards in the hanging wall of earthquake fault zone was obviously higher than that in the foot wall and the width of strong development zone in the hanging wall was about 10 km; (3) the topographical slope was a main factor which controlled the development of earthquake geo- hazards and a vast majority of hazards were distributed on the slopes of 20° to 50°; (4) the earthquake geohazards had a corresponding relationship with the elevation and micro-landform, for most hazards happened in the river valleys and canyon sections below the elevation of 1500 to 2000 m, particularly in the upper segment of canyon sections (namely, the turning point from the dale to the canyon). Thin ridge, isolated or full-face space mountains were most sensitive to the seismic wave, and had a striking amplifying effect. In these areas, collapses and landslides were most likely to develop; (5) the study also showed that different lithologies determined the types of geohazards, and usually, landslides oc- curred in soft rocks, while collapses occurred in hard rocks. | HUANG RunQiu LI WeiLe | 2009 | Science China(Technological Sciences)2009，52，4： | 30 |
| 10 | Distribution of high-risk human papillomavirus genotype prevalence and attribution to cervical precancerous lesions in rural North China显示文摘Objective: Precise prevention is more desired for cervical cancer due to the huge population, high prevalence of human papillomavirus(HPV) infection in China and the vision of screen-and-treat strategies in low-and middleincome countries(LMICs). Considerations of combining type-specific prevalence and attribution proportion to high-grade cervical intraepithelial neoplasia are informative to more precise and effective region-specific cervical cancer prevention and control programs. The aim of the current study was to determine the genotype distribution of HPV and attribution to cervical precancerous lesions among women from rural areas in North China.Methods: A total of 9,526 women participated in the cervical cancer screening project in rural China. The samples of women who tested positive for HPV were retested with a polymerase chain reaction(PCR)-based HPV genotyping test. The attribution proportion of specific high-risk human papillomavirus(HR-HPV) types for different grades of cervical lesions was calculated by using the type contribution weighting method.Results: A total of 22.2%(2,112/9,526) of women were HR-HPV positive and HPV52(21.7%) was the most common HR-HPV genotype, followed by HPV58(18.2%), HPV53(18.2%) and HPV16(16.2%). The top three genotypes detected in HR-HPV-positive cervical intraepithelial neoplasia(CIN)1 were HPV16(36.7%), HPV58(20.4%), HPV56(15.3%). Among CIN2+, the most frequent genotypes were HPV16(75.6%), HPV52(17.8%),HPV58(16.7%). HPV16, 56, 58, 53, 52, 59, 68, and 18 combined were attributed to 84.17% of all CIN1 lesions,and HPV16, 58, and 52 combined were attributed to 86.98% of all CIN2+ lesions.Conclusions: The prevalence of HR-HPV infection among women from rural areas in North China was high and HPV16, HPV58, HPV52 had paramount attributable fraction in CIN2+. Type-specific HPV prevalence and attribution proportion to cervical precancerous lesions should be taken into consideration in the development of vaccines and strategy for screening in this population. | Shuang Zhao Xuelian Zhao Shangying Hu Jessica Lu Xianzhi Duan Xun Zhang Feng Chen Fanghui Zhao | 2019 | Chinese Journal of Cancer Research2019，31，4： | 30 |
| 11 | Climatological distribution of lightning density observed by satellites in China and its circumjacent regions显示文摘The 0.5°× 0.5°grid resolution distribution of lightning density in China and its circumjacent regions have been analyzed by using the satellite-borne OTD (Apr 1995-Mar 2000) and LIS (Dec 1997-Mar 2003) databases. It is shown that: (ⅰ) Firstly, the variability of the lightning density (LD) is particularly pronounced over the different subareas, 9 times greater over the south than the north side of Himalayas Mountains, 2.5 times greater over the eastern than the western area of China. While the maximum and minimum LD are respectively 31.4fl/km2/a (in Guangzhou region) and less than 0.2fl/km2/a (in the desert of western China). Secondly, the LD of China's continent regularly varies with latitude and distance off coast, which is consistent with annual mean precipitation in varying trend. In conclusion, the Qinghai-Tibet Plateau, the China's three-step staircase topography and the latitude are three important factors affecting macro-scale characteristics of the LD distribution. (ⅱ) The regional differences in LD distribution are closely related to the mesoscale orographic forcing. In the eastern humid regions of China, the high LD belts often appear along the mesoscale mountains (with south-north or northeast-southwest direction, 500-1500 m ASL) and hills, while the low LD belts often appear on the plain and basin (valley) between the mountains. But in the western cold and arid regions of China, the relatively high LD belts mostly appear on the Qinghai Lake area of the southern side of Qilian Mountain, Yili River valley, the basin between Tanggula Mountains and Nyainqetanglha. On the coastal land, the high LD centers appear in regions where mountain and hill and large cities are located. This seems to be related to the interaction between the sea-land breeze and mountain-valley wind or city heat island effect. (ⅲ) The China Sea is one of the relatively high LD zones on global oceans. It is very interesting that a high LD belt is located along the Kuroshio area. It is a new fact that the high temperature and high salinity characteristics of Kuroshio have obvious effect on the local deep convective activity. In addition, the intracloud/cloud-to-ground lightning ratio is close to 3.0 in Anhui Province. | MA Ming TAO Shanchang ZHU Baoyou Lu Weitao | 2005 | Science China Earth Sciences2005，48，2： | 26 |
| 12 | Comparison of climatic threshold of geographical distribution between dominant plants and surface pollen in China显示文摘The geographical distribution of dominant plant species in China was georeferenced and climatic variables were interpolated into all grids.Accordingly,the percentage distributions of principal pollen taxa based on 1860 surface pollen sites in China were selected and the related climate values were interpolated with the same method. The geographical and climatic comparison between the two data-sets indicated that the climate threshold of most pollen taxa from surface pollen is coherent with plant distributions. The climatic envelopes of dominant plant are mostly accordant with those of pollen taxa at certain levels. However, some distinct offsets of the climate ranges exist between the two datasets for most pollen taxa identified at family level, such as Ericaceae,Asteraceae, Poaceae and Chenopodiaceae. The present study provides for the first time rich information on temperature and precipitation in relation to pollen and plant distribution based on the datasets on a continental scale useful for global ecological modeling and Quaternary palaeoclimate reconstruction. | CHEDDADI Rachid BEAUDOUIN Celia | 2008 | Science China Earth Sciences2008，51，8： | 26 |
| 13 | The structure of turbulent flow through submerged flexible vegetation显示文摘The hydrodynamics of turbulent flow through submerged flexible vegetation is investigated in a flume using acoustic Doppler velocimetery(ADV)measurements.The flow characteristics such as the energetics and momentum transfer derived from convcntional spectral and quadrant analyses are considered as the flow encounters a finite vegetation patch.Consistent with numerous canopy flow experiments,a shear layer and coherent vortex structures near the canopy top emerge caused by Kelvin-Helmholtz instabilities after the flow equilibrates with the vegetated layer.These in stabilities are commonly attributed to velocity differences between non-vegetated and vegetated canopy layers in agreement with numerous experiments and simulations conducted on dense rigid canopies.The power-spectral density function for vertical velocity turbulent fluctuations at different downstream positions starting from the edge of the vegetation layer are also computed.For a preset water depth,the dominant dimensionless frequency is found to be surprisingly invariant around 0.027 despite large differences in vegetation densities.The ejection and sweep events significantly contribute to the Reynolds stresses near the top of the vegetation.The momentum flux carried by ejections is larger than its counterpart carried by the sweeps above the canopy top.However,the momentum flux carried by sweeps is larger below the top of the canopy. | Wen-xin Huai Jiao Zhang Gabriel G.Katul Yong-guang Cheng Xue Tang Wei-jie Wang | 2019 | Journal of Hydrodynamics2019，31，2： | 26 |
| 14 | Performances evaluation of four typical unmanned aerial vehicles used for pesticide application in China显示文摘In recent years,unmanned aerial vehicles(UAVs)for plant protection have achieved rapid development in China.In order to test and evaluate the performances of pesticides application and development status of UAVs in China,four typical UAV models were selected to test the spraying coverage,penetrability,droplets density and the work efficiency.The results showed that the deposition and spraying liquid coverage were inconsistent both in lateral and longitudinal direction.Under the condition of the similar amount of spray volume and operation parameters,the volume median diameter(VMD)of the droplet was negatively correlated with the coverage density.The failure of the UAVs for plant protection mainly took up on the blockage of nozzle,transfusion tube and the liquid pump.The failure rate of UAVs took up 3.73%-4.36%of the total working time.The operation of UAVs during ground service took up 50%of the total working time,the preparation work took up 10%,and the route planning took up around 10%,while net operation time only took up around 30%.On the whole,the high efficiency of UAV was not fully achieved;the daily operated area was not in a satisfactory level now.The spraying performances of UAVs still need further improvement. | Wang Shilin Song Jianli He Xiongkui Song Le Wang Xiaonan Wang Changling Wang Zhichong Ling Yun | 2017 | International Journal of Agricultural and Biological Engineering2017，10，4： | 25 |
| 15 | Assessment and sequencing of air target threat based on intuitionistic fuzzy entropy and dynamic VIKOR显示文摘In view of the fact that traditional air target threat assessment methods are difficult to reflect the combat characteristics of uncertain, dynamic and hybrid formation, an algorithm is proposed to solve the multi-target threat assessment problems. The target attribute weight is calculated by the intuitionistic fuzzy entropy(IFE) algorithm and the time series weight is gained by the Poisson distribution method based on multi-times data. Finally,assessment and sequencing of the air multi-target threat model based on IFE and dynamic Vlse Kriterijumska Optimizacija I Kompromisno Resenje(VIKOR) is established with an example which indicates that the method is reasonable and effective. | ZHANG Kun KONG Weiren LIU Peipei SHI Jiao LEI Yu ZOU Jie | 2018 | Journal of Systems Engineering and Electronics2018，29，2： | 24 |
| 16 | Red blood cell distribution width and ischaemic stroke显示文摘The red blood cell distribution width(RDW)is a measure of red blood cell(RBC)size heterogeneity,which is easily calculated by dividing the SD of erythrocyte volumes for the mean corpuscular volume.Recent reporter suggested that,besides haematological diseases and anaemia,many human disorders may be closely associated with the elevated RDW.A literature review has revealed the RDW may be closely related to the development of ischaemic stroke,carotid artery atherosclerosis and cerebral embolism.Higher RDW could independently predict adverse outcomes in patients in these conditions. | Gang-Hua Feng Hai-Peng Li Qiu-Li Li Ying Fu Ren-Bin Huang | 2017 | Stroke & Vascular Neurology2017，2，3： | 24 |
| 17 | The biomass and aboveground net primary productivity of Schima superba-Castanopsis carlesii forests in east China显示文摘The biomass and productivity of Schima superba-Castanopsis carlesii forests in Tiantong,Zhejiang Province,were determined using overlapping quadrants and stem analyses.The total community biomass was(225.3±30.1) t hm-2,of which the aboveground parts accounted for 72.0% and the underground parts accounted for 28.0%.About 87.2% of biomass existed in the tree layer.The resprouting biomass was small,of which over 95.0% occurred in the shrub layer.The productivity of the aboveground parts of the community was(386.8±98.9) g m-2a-1,in which more than 96.0% was present at the tree level.The trunk's contribution to productivity was the greatest,while that of leaves was the smallest.In China,the community biomass of subtropical evergreen broadleaved forests differs significantly with the age of the forest.The community biomass of the 52-year-old S.superba-C.carlesii forests in this study was lower than the average biomass of subtropical evergreen broadleaved forests in China,and was lower than the biomass of other subtropical evergreen broadleaved forests elsewhere in the world.Moreover,its productivity was lower than the model estimate,indicating that without disturbance,this community has great developmental potential in terms of community biomass and productivity. | YANG TongHui1,2,SONG Kun1,DA LiangJun1*,LI XiuPeng3 & WU JianPing1 1School of Resources and Environment Science,East China Normal University,Shanghai 200062,China 2Ningbo Academy of Agricultural Science,Ningbo 315040,China 3Ningbo Technology Extension Center for Forestry and Specialty Forest Products,Ningbo 315012,China | 2010 | Science China(Life Sciences)2010，53，7： | 23 |
| 18 | The distribution rule and seepage effect of the fractures in the ultra-low permeability sandstone reservoir in east Gansu Province,Ordos Basin显示文摘To study the impact of the fractures on development in the ultra-low permeability sandstone reservoir of the Yangchang Formation of the Upper Triassic in the Ordos Basin,data on outcrops,cores,slices,well logging and experiments are utilized to analyze the cause of the formation of the fractures,their distribution rules and the control factors and discuss the seepage flow effect of the fractures. In the studied area developed chiefly high-angle tectonic fractures and horizontal bedding fractures,inter-granular fractures and grain boundary fractures as well. Grain boundary fractures and intragranular fractures serve as vital channels linking intragranular pores and intergranular solution pores in the reservoir matrix,thus providing a good connectivity between the pores in the ultra-low perme-ability sandstone reservoir. The formation of fractures and their distribution are influenced by such external and internal factors as the palaeo-tectonic stress field,the reservoir lithological character,the thickness of the rock layer and the anisotropy of a layer. The present-day stress field influences the preservative state of fractures and their seepage flow effect. Under the tec-tonic effect of both the Yanshan and Himalayan periods,in this region four sets of fractures are distributed,respectively assuming the NE-SW,NW-SE,nearly E-W and nearly S-N orientations,but,due to the effect of the rock anisotropy of the rock formation,in some part of it two groups of nearly orthogonal fractures are chiefly distributed. Under the effect of the present-day stress field,the fractures that assume the NE-SW direction have a good connectivity,big apertures,a high permeability and a minimum starting pressure,all of which are main advantages of the seepage fractures in this region. With the development of oilfields,the permeability of the fractures of dif-ferent directions will have a dynamic change. | ZENG LianBo1,GAO ChunYu2,QI JiaFu1,WANG YongKang2,LI Liang2 & QU XueFeng2 1 State Key Laboratory of Petroleum Resource and Prospecting,China University of Petroleum,Beijing 102249,China 2 Changqing Oilfield Branch,PetroChina,Xi’an 163517,China | 2008 | Science China Earth Sciences2008，51，S2： | 22 |
| 19 | Trends in particulate matter and its chemical compositions in China from 2013–2017显示文摘Accurate determination of the atmospheric particulate matter mass concentration and chemical composition is helpful in exploring the causes and sources of atmospheric enthalpy pollution and in evaluating the rationality of environmental air quality control strategies.Based on the sampling and chemical composition data of PM2.5 in different key regions of China in the CARE-China observation network,this research analyzes the environmental air quality data released by the China National Environmental Monitoring Centre during the studied period to determine the changes in the particulate matter mass concentration in key regions and the evolution of the corresponding chemical compositions during the implementation of the Action Plan for Prevention and Control of Air Pollution from 2013-2017.The results show the following.(1)The particulate matter mass concentration in China showed a significant downward trend;however,the PM2.5 annual mass concentration in 64%of cities exceeds the New Chinese Ambient Air Quality Standard(CAAQS)GradeⅡ(GB3095-2012).The region to the east of the Taihang Mountains,the Fenhe and Weihe River Plain and the Urumqi-Changji regions in Xinjiang,all have PM2.5 concentration loading that is still high,and heavy haze pollution occurred frequently in the autumn and winter.(2)During the heavy pollution in the autumn and winter,the concentrations of sulfate and organic components decreased significantly.The mean SO42-concentration in PM2.5 decreased by 76%,12%,81%and 38%in Beijing-Tianjin-Hebei(BTH),the Pearl River Delta(PRD),the Sichuan-Chongqing region(SC)and the Fenhe and Weihe River Plain,respectively.The mean organic matter(OM)concentration decreased by 70%,44%,48%and 31%,respectively,and the mean concentration of NH4+decreased by 68%,1.6%,38%and 25%,respectively.The mean elemental carbon(EC)concentration decreased by 84%and 20%in BTH and SC,respectively,and it increased by 61%and 11%in the PRD and Fenhe and Weihe River Plain,respectively.The mean concentration of mineral and unresolved chemical components(MI)dropped by 70%,24%and 13%in BTH,the PRD and the Fenhe and Weihe River Plain,respectively.The change in the PM2.5 chemical composition is consistent with the decrease of the PM2.5mass concentration.(3)In 2015,the mean OM concentration contributions to fine particles and coarse particles were 13-46%and 46-57%,respectively,and the mean MI concentration contributions to fine particles and coarse and particles were 31-60%and 39-73%,respectively;these values are lower than the 2013 values from the key regions,which is the most important factor behind the decrease of the particulate matter mass concentration.From 2013 to 2015,among the chemical components of different particle size fractions,the peak value of the coarse particle size fraction decreased significantly,and the fine particle size fractions of SO42-,NO3-,and NH4+decreased with the decrease of the particulate matter mass concentration in different particle size fractions.The fine-particle size peaks of SO42-,NO3-and NH4+shifted from 0.65-1.1μm to the finer size range of0.43-0.65μm during the same time frame. | Yuesi WANG Wenjie LI Wenkang GAO Zirui LIU Shili TIAN Rongrong SHEN Dongsheng JI Shuai WANG Lili WANG Guiqian TANG Tao SONG Mengtian CHENG Gehui WANG Zhengyu GONG Jiming HAO Yuanhang ZHANG | 2019 | Science China Earth Sciences2019，62，12： | 23 |
| 20 | Significant concurrent decrease in PM_(2.5) and NO_(2) concentrations in China during COVID-19 epidemic显示文摘The strict control measures and social lockdowns initiated to combat COVID-19 epidemic have had a notable impact on air pollutant concentrations.According to observation data obtained from the China National Environmental Monitoring Center,compared to levels in 2019,the average concentration of NO_(2) in early 2020 during COVID-19 epidemic has decreased by 53%,50%,and 30%in Wuhan city,Hubei Province(Wuhan excluded),and China(Hubei excluded),respectively.Simultaneously,PM_(2.5) concentration has decreased by 35%,29%,and 19%in Wuhan,Hubei(Wuhan excluded),and China(Hubei excluded),respectively.Less significant declines have also been found for SO_(2) and CO concentrations.We also analyzed the temporal variation and spatial distribution of air pollutant concentrations in China during COVID-19 epidemic.The decreases in PM_(2.5) and NO_(2) concentrations showed relatively consistent temporal variation and spatial distribution.These results support control of NO x to further reduce PM_(2.5) pollution in China.The concurrent decrease in NOx and PM_(2.5) concentrations resulted in an increase of O3 concentrations across China during COVID-19 epidemic,indicating that coordinated control of other pollutants is needed. | Biiuu Chu Shuping Zhang Jun Liu Qingxin Ma Hong He | 2021 | Journal of Environmental Sciences2021，33，1： | 21 |
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