维普中文期刊产品整合服务
179篇 您的检索式:作者名="Yu 3"
    题名 作者 年代 出处 被引量
1A study of interaction between surface water and groundwater using environmental isotope in Huaisha River basin显示文摘The surface water and groundwater are important components of water cycle, and the interaction between surface water and groundwater is the important part in water cycle research. As the effective tracers in water cycle research, environmental isotope and hydrochemistry can reveal the interrelationships between surface water and groundwater effectively. The study area is the Huaisha River basin, which is located in Huairou district, Beijing. The field surveying and sampling for spring, river and well water were finished in 2002 and 2003. The hydrogen and oxygen isotopes and water quality were measured at the laboratory. The spatial characteristics in isotope and evolution of water quality along river lines at the different area were analyzed. The altitude effect of oxygen isotope in springs was revealed, and then using this equation, theory foundation for deducing recharge source of spring was estimated. By applying the mass balance method, the annual mean groundwater recharge rate at the catchment was estimated. Based on the groundwater recharge analysis, combining the hydrogeological condition analysis, and comparing the rainfall-runoff coefficients from the 1960s to 1990s in the Huaisha River basin and those in the Chaobai River basin, part of the runoff in the Huaisha River basin is recharged outside of this basin, in other words, this basin is an un-enclosed basin. On the basis of synthetically analyses, combining the compositions of hydrogen and oxygen isotopes and hydrochemistry, geomorphology, geology, and watershed systems characteristics, the relative contributions between surface water and groundwater flow at the different areas at the catchments were evaluated, and the interaction between surface water and groundwater was re- vealed lastly.SONG Xianfang1, LIU Xiangchao1, 2, XIA Jun1, YU Jingjie1 & TANG Changyuan1, 3 1. Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographical Sciences and Natural Re- sources Research, Chinese Academy of Sciences, Beijing 100101, China 2. College of River and Ocean, Chongqing Jiaotong University, Chongqing 400074, China 3. Chiba University, Chiba 263-8522, Japan 2006Science China Earth Sciences2006,49,12:34
2The prognostic value of preoperative serum levels of CEA,CA19-9 and CA72-4 in patients with colorectal cancer显示文摘INTRODUCTIONCarcinoembryonic antigen ( CEA) , originally described by Gold and Freedman [1] in 1965, is now an acknowledged member of immunoglobulin superfamily[2],with a role as an intracellular adhesion molecule[3].Carbohydrate antigen 19-9(CA19-9), obtained with a monoclonal antibody produced by immunizing a monoclonal antibody produced by immunizing a mouse with a colonic cancer cell line in 1979[4],is a ligand for E-selectin that plays an important role in the addhesion of cancer cells to endothelial cells [5,6].Chao Xu Zheng~1 Wen Hua Zhan~1 Ji Zong Zhao~2 Dong Zheng~3 Dong Ping Wang~1 Yu Long He~1 Zhang Qing Zheng~1 ~1Department of General Surgery,~2Laboratory of Surgery,~3Department of Medicine,First Affiliated Hospital,Sun Yat-Sen University of Medical Sciences,Guangzhou 510080,Guangdong Province,ChinaDr.Chao Xu Zheng now working as a surgeon and lecturer in the Department of General Surgery,First Affiliated Hospital,Sun Yat-Sen University of Medical Sciences,who is a Ph.D.student,having 7 papers published. 2001World Journal of Gastroenterology2001,7,3:25
3Cytochrome P450 2E1 genetic polymorphism and gastric cancer in Changle,Fujian Province显示文摘AIM: Genetic polymorphism in enzymes of carcinogen metabolism has been found to have the influence on the susceptibility to cancer. Cytochrome P450 2E1 ( CYP2 E1) is considered to play an important role in the metabolic activation of procarcinogens such as N-nitroscoamines and Iow molecular weight organic compounds. The purpose of this study is to determine whether CYP450 2Elpolymorphisms are associated with risk s of gastric cancer.METHODS: We conducted a population based case-control study in Changle county, Fujian Province, a high-risk region of gastric cancer in China. Ninety-one incident gastric cancer patients and ninety-four healthy controls were included in our study. Datas including dsmographic characteristcs, diet intake, and alcohol and tobacco consumption of indivduals in our study were completed by a standardized questionnaire. PCR-RFLP revealed three genotypes: heterozygote (C1/C2) and two homozygotes (C1/C1 and C2/C2) in CYP2E1.RESULTS: The frequency of variant genotypes (C1/C2 and C2/C2) in gastric cancer cases and controls was 36.3% and 24.5%, respectively. The rare homozygous C2/C2 genotype was found in 6 indivduals in gastric cancer group(6.6%),whereas there was only one in the control group (1.1%).However, there was no statistically significan difference between the two groups (two-tailed Fisher′s exact test, P =0.066). Indivduals in gastric cancer group were more likely to carry genotype C1/C2 (odds ratio, OR = 1.50) and C2/C2(OR = 7.34) than indivduals in control group (X2 = 4.597, for trend P=0.032). The frequencies of genofypes with the C2allele ( C1/C2 and C2/C2 genotypes) were compared with those of genotypes without C2 allele ( C1/C1 genotype )among indivduals in gastric cancer group and control group according to the pattern of gastric cancer risk factors. The results show that indivduals who exposed to these gastric cancer risk factors and carry the C2 allele seemed to have a higher risk of developing gastric cancer.CONCLUSION: Polymorphism of CYP2E1 gene may have some effct in the development of gastric cancer in Changle county, Fujian Province.Lin Cai~1 Shun-Zhang Yu~2 Zuo-Feng Zhang~3 1 Department of Epidemiology,Fujian Medical University,Fuzhou 350004,Fujian Province,China2 Department of Epidemiology,Shanghai Medical University,Shanghai 200032,China3 Department of Epidemiology,UCLA School of Public Health,Los Angeles California,USA 2001World Journal of Gastroenterology2001,7,6:25
4Antisense to cyclin D1 reverses the transformed phenotype of human gastric cancer cells显示文摘INTRODUCTIONStudiesonthefunctionsofcelularprotooncogenesandtumorsuppresorgenesindicatethatmostofthesegenesmediatesignaltrans...CHEN Bing 1, ZHANG Xue Yong 2, ZHANG Yu Jing 3, ZHOU Ping 3, GU Yan 4 and FAN Dai Ming 2 1999World Journal of Gastroenterology1999,5,1:23
5The cloning of 3'-truncated preS/S gene from HBV genomic DNA and its expression in transgenic mice显示文摘INTRODUCTIONHepatitis B virus (HBV) is regarded as one of themain etiologic factors involved in the developmentof human hepatocellular carcinoma (HCC).The open reading frame (orf)of X gene of HBVencoded a transactivating factor is the evidence thatstrongly supported the notion that the X gene ofHBV DNA integrated in HCC genomic DNA couldcontribute to the carcinogenesis of liver cells byactivation of some related cellular genesYi Ping Hu~1 Yu Cheng Yao~1 Jian Xiu Li~1 Xin Min Wang~1 Hong Li~2 Zhong Hua Wang~1 Zhang Heng Lei~3 1 Department of Cell Biology,Second Military Medical University,Shanghai 200433,China 2 Department of Biology,Department of Basic Medicine,West-China University of Medical Sciences,Chengdu 610041,China 3 Department of Biology,North Sichuan Medical College,Nanchong 637007,China 2000World Journal of Gastroenterology2000,6,5:18
6Nutrients concentration and changes in decade-scale in the central Bohai Sea显示文摘The nutrients contents and distributions are discussed briefly, based on the data obtained in 1998~1999. Besides explanation of the results,a 20 a time series data of nutrients and biological parameters for central Bohai Sea are reviewed. It is found that both concentration and relative content of nutrients have been changed dramatically. The increase of nitrogen and decrease of phosphate and silicate led to the dramatically increase of N/P ratio and the decrease of Si/N ratio. The situation of nitrogen limiting in central Bohai Sea is gradually changing to that of relative lack of phosphate and silicate. The decrease of the Huanghe River input to the Bohai Sea may be responsible for this change. These in turn may limit the growth of diatom and thus promote the development of pyrrophyta if other conditions (e.g. temperature and hydrodynamics) are suitable. We conclude that this may be the major inducement factor of pyrrophyta red tide in the Bohai Sea.Yu Zhigang 1,Mi Tiezhu 1,Yao Qingzhen 1,Xie Baodong 1,Zhang Jing 11 .CollegeofChemistryandChemicalEngineering ,OceanUniversityofQingdao ,Qingdao 2 6 6 0 0 3 ,China 2001Acta Oceanologica Sinica2001,20,1:18
7Multi-level decollement zones and detachment deformation of Longmenshan thrust belt,Sichuan Basin,southwest China显示文摘As is well known that many decollement layers were developed in the Longmenshan thrust belt,Si-chuan Basin,China. Through field investigation,explanation of seismic profiles and analysis of the balanced sections,we can divide the decollement zones into 3 categories: (1) the deep level decolle-ment zones,including the crust-mantle decollement layer,intracrustal decollement layer,and presinian basal decollement layer. The main structural styles of their deformation are the crust-mantle decoup-ling detachment deformation,the basal ductile shear deformation,etc.; (2) the middle level decollement zones,including the Cambrian-Ordovician decollement layer,the Silurian decollement layer,etc.,the main structural styles of their deformation are the isopachous fold,the angular fold,the saddle struc-ture,and the combination styles of them; and (3) the shallow level decollement zones,including the Xujiahe Formation decollement layer of Upper Triassic and the Jurassic decollement layers,the main structural styles of their deformation are the thrust-nappe tectonic,the pop-up,the triangle zone ,the duplex,etc. Multi-level decollement zones not only made the Longmenshan thrust belt develop many different deformation styles from deep place to shallow place,but also made some local areas have the superimposition of the tectonic deformation apparently. This study indicates that the multi-level de-collement zones have a very important effect on the shaping and evolution of the Longmenshan thrust belt.TANG LiangJie1,2,3,YANG KeMing4,JIN WenZheng1,2,3,L ZhiZhou4 & YU YiXin1,2,3 1 State Key Laboratory of Petroleum Resource and Prospecting,China University of Petroleum,Beijing 102249,China 2 Key Laboratory for Hydrocarbon Accumulation Mechanism,China University of Petroleum,Ministry of Education,Beijing 102249,China 3 Basin and Reservoir Research Center,China University of Petroleum,Beijing 102249,China 4 Southwest Division Company,SINOPEC,Chengdu 610081,China 2008Science China Earth Sciences2008,51,S2:18
8Radiometric cross-calibration of the CBERS-02 CCD camera with the TERRA MODIS显示文摘For the application of the CCD camera, the most important payload on CBERS-02, the key is to provide long-term stable radiometric calibration coefficients. Although the vicarious calibration had been proved successful, it had its limitations such as test site requirement and unsuitable for historical data. Cross-calibration is one of the alternative methods, but it needs synchro surface spectrum to achieve spectral band matching factors. Our effort is to probe the influences on these factors. Simulations with a lot of surface spectrum showed that the factors changed with the viewing geometry, atmospheric condition and surface targets. However, simulating with the same viewing geometry and atmospheric condition, the spectral band matching factors of the same or similar surface targets’ spectrum acquired from different dates and different places would like to be consistent to each other within 1%―5%. Thus, the synchro measurement data can be substituted by the same or similar target from other source. Based on this method, using the MODIS as the reference, the cross-calibration was performed for CCD camera. The research demonstrated that the traditional method with single calibration site was inappropriate for CCD camera, since the offsets for its four spectral bands were not zeros. With four calibration sites, these offsets were obtained. And the camera was detected to degrade with dates based on four times of cross-calibrations.LI Xiaoying1,2,3, GU Xingfa1,3,4, MIN Xiangjun5, YU Tao1,3, FU Qiaoyan5, ZHANG Yong1,2,3 & LI Xiaowen1,3 1. State Key Laboratory of Remote Sensing Science, Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University, Beijing 100101, China 2. Graduate University of Chinese Academy of Sciences, Beijing 100039, China 3. The Center for National Spaceborne Demonstration, Beijing 100101, China 4. Institut National de la Recherche Agronomique, Climat Sol Environnement, 84914 Avignon, France 5. China Center for Resource Satellite Data and Application, Beijing 100830, China 2005Science China(Technological Sciences)2005,48,S2:15
9An accurately delineated Permian-Triassic Boundary in continental successions显示文摘The Permian-Triassic Boundary Stratigraphic Set (PTBST), characteristic of the GSSP section of Meishan and widespread in marine Permian-Triassic Boundary (PTB) sequences of South China, is used to trace and recognize the PTB in a continental sequence at Chahe (Beds 66f―68c). Diversified Permian plant fossils extended to the PTBST, and a few relicts survived above that level. Sporomorphs are dominated by fern spores of Permian nature below the PTBST, above which they are replaced by gymnosperm pollen of Triassic aspect. In the nearby Zhejue Section, the continental PTBST is charac- terized by the fungal 'spike' recorded in many places throughout the world. The boundary claybeds (66f and 68a,c) of the PTBST are composed of mixed illite-montmorillonite layers analogous with those at Meishan. They contain volcanogenic minerals such as β quartz and zircon. U/Pb dating of the upper claybed gives ages of 247.5 and 252.6 Ma for Beds 68a and 68c respectively, averaging 250 Ma. In con- trast to the situation in Xinjiang and South Africa, the sediment sequence of the Permian-Triassic tran- sition in the Chahe section (Beds 56―80) become finer upward. Shallowing and coarsening upward is not, therefore, characteristic of the Permian-Triassic transition everywhere. The occurrence of relicts of the Gigantopteris Flora in the Kayitou Fm. indicates that, unlike most marine biota, relicts of this pa- leophytic flora survived into the earliest Triassic. It is concluded that Bed 67 at Chahe corresponds to Bed 27 at Meishan, and that the PTB should be put within the 60-cm-thick Bed 67b④, now put at its base tentatively. This is the most accurate correlation of the PTB in continental facies with that in the marine GSSP.YIN HongFu1, YANG FengQing2, YU JianXin2, PENG YuanQiao1, WANG ShangYan3 & ZHANG SuXin1 1 Laboratory of Biological and Environmental Geology, China University of Geosciences, Wuhan 430074, China 2 State Key Laboratory of Geological Process and Mineral Resources, China University of Geosciences, Wuhan 430074, China 3 Geological Survey of Guizhou Province, Guiyang 550011, China 2007Science China Earth Sciences2007,50,9:13
10A New (t, n) Threshold Signature Scheme Withstanding the Conspiracy Attack显示文摘A conspiracy attack is proposed to show that Wang-Li’s scheme is insecure, because any t or more group members can impersonate other t members to sign any message without holding the responsibility. To avoid the conspiracy attack, this paper presents a new (t,n) threshold signature scheme with traceable signers.XIE Qi 1,2, YU Xiu-yuan 3 1.Department of Mathematics, Zhejiang University, Hangzhou 310027, Zhejiang,China 2.School of Information and Engineering, Hangzhou Teachers College, Hangzhou 310012, Zhejiang, China 3.Hangzhou Teachers College, Hangzhou 310012, Zhejiang, China 2005Wuhan University Journal of Natural Sciences2005,10,1:13
11Experimental study on mechanism and protection of stress ulcer produced by explosive noise显示文摘INTRODUCTIONExplosivenoisemayproduceanenormousadverseeffectonhumanbodyandmind.Ithasbeenknownthatpepticulceroccuredmuchmorefre...LIU Guo Shi 1, HUANG Yu Xin 1, LI Shuan Wei 2, PAN Bo Rong 3, WANG Xin 1, SUN Da Yong 1 and WANG Qing Li 1 1998World Journal of Gastroenterology1998,4,6:13
12The study of neighboring nucleotide composition and transition/transversion bias显示文摘Base substitution is one of the raw fuels that produce genetic variation and drive evolu-tion. Recent studies have shown that the genome components affect mutation patterns to some extent. In order to infer the correlation between the Transition/Transversion ratio (Ts/Tv) and the number of immediately adjacent A&T nucleotides, we investigated 3611007 Oryza sativa SNPs (including 45462 coding SNPs, and 242811 intronic SNPs) and 32019 Arabidopsis SNPs. The results show that Ts/Tv is negatively correlated with the number of immediately adjacent A&T in O. sativa and Arabidopsis. We further calculated AT2 (the number of SNPs whose immediately adjacent nucleotides are either A or T) and AT0 (the number of SNPs whose immediately adjacent nucleotides are either C or G) for all 6 types of SNPs. C/G SNP of O. sativa and Arabidopsis has the highest AT2/AT0, which denotes C/G SNP may be influenced by the adjacent A&T nucleotides mostly. For SNPs in O. sativa, the neighboring effect of A&T nucleotides is limited to 2 nucleotides on both sides; for SNPs in Arabidop-sis, the effect extends no more than 4 nucleotides on both sides.ZHAO Hui1,3*, LI Qizhai1,2,3*, LI Jun1, ZENG Changqing1, HU Songnian1 & YU Jun1 1. Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100030, China 2. Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing 100080, China 3. Graduate University of Chinese Academy of Sciences, Beijing 100039, China 2006Science China(Life Sciences)2006,49,4:12
13Reverse reconciliation for continuous variable quantum key distribution显示文摘An efficient and practical post-processing technique based on reverse reconciliation for continuous variable quantum key distribution is proposed and simulated with low-density parity check (LDPC) codes. MultiLevel Coding/ MultiStage Decoding, which fully utilizes optimization technique such as vector quantization and iterative decoding and the optimal channel coding most close to the Shannon limit, was used to realize efficient reverse reconciliation algorithm. Simulation results showed that the proposed method can improve the secure key distribution rate to 2.2 kb/s and the coding efficiency to 0.89 over 20 km in single-mode optical fiber. Moreover, there still is room for much improvement.LU ZhiXin 1,2 , YU Li 1,2 , LI Kang 1,2 , LIU BingCan 1,2,3 , LIN JianGui 1,2 , JIAO RongZhen 1,2 & YANG BoJun 1,21 School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China 2 Key Laboratory of Information Photonics and Optical Communication, Ministry of Education, Beijing University of Posts and Telecommunications, Beijing 100876, China 3 Department of Fundamental Courses, Academy of Armored Force Engineering, Beijing 100072, China 2010Science China(Physics,Mechanics & Astronomy)2010,53,1:12
14Vertical quantitative and dominant population distribution of the bacteria isolated from the Muztagata ice core显示文摘Vertical distribution of the main bacteria isolated from the Muztagata ice core (about 22.4 m) was investigated by means of cultivation and 16S rRNA sequence analysis. The results showed that the amount of culturable bacteria fluctuated with ice core depth, and was more in dirty layer than in clean ice, which suggested the close corresponding relationship between high input of the bacteria deposited by wind and snowflow and dirty layer. Most of the bacteria were psychrophiles and psychrotolerants, including α- and γ-proteobacteria, Cryobacterium psychro-philum, CFB (Cytophaga-Flavobacterium-Bacteroides) group, high-G+C gram-positive bacteria (HGC). Acinetobacter sp. and HGC repeatly occurred in different ice depths, and their quantita-tive distribution was consistent with the change of the total amount of culturable bacteria with depth, which suggested the main bio-indicator; while Flavobacterium, Cryobacterium psychro-philum, and α-proteobacteria, also functioned as a secondary indicator of climatic and environ-mental changes. This study is the first report concerning continuous quantitative variation and pattern of the main culturable bacteria in ice core section.XIANG Shurong1, YAO Tandong1, 2, AN Lizhe1, 3, WU Guangjian2, XU Baiqing2, MA Xiaojun 3, LI Zhen1, WANG Junxia1 & YU Wusheng1 1. Key Laboratory of Ice Core and Cold Regions Environment, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China 2. Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100085, China 3. College of Life Science, Lanzhou University, Lanzhou 730000, China 2005Science China Earth Sciences2005,48,10:12
15Research on the dry intrusion accompanying the low vortex precipitation显示文摘By employing the 6.7μm satellite vapor cloud images and NCEP/NCAR 1°×1° reanalysis datasets, the characteristics and mechanism of the dry intrusion, as well as its impacts on the low vortex precipita- tion at the Meiyu front are explored in this paper. It is found that the formation,development and main- tenance of the low vortex precipitation at the Meiyu front are closely related to the evolution of the dry intrusion. The dry intrusion is characterized by high potential vorticity (PV), low humidity and cold air. The dry intrusion exhibits as an obvious dark zone on vapor cloud images, an area in which atmos- pheric relative humidity is lower than 60%. However, the features of the dry intrusion on the vapor im- ages are clearer than that of the humidity field, for the former is the digital vapor cloud images with high temporal and spatial resolution, and it can be used to explore the finer characteristics of the develop- ment, evolution and supplement of the intrusion during the development of the low vortex. The dry intrusion impacts accompanying the low vortex precipitation at the Meiyu front come from all levels of the troposphere, with the strongest intrusion located at the upper troposphere. The dry and cold air intrudes the vicinity of the low vortex from the upper isentropic surface to the lower one, slanting eastward from lower to higher level. The low vortex precipitation region is usually situated in front of the dry intrusion where the relative humidity gradient is higher. The research also reveals that the mechanism of the dry intrusion is that the high potential vorticity descends from the upper troposphere to the lower level, therefore, the dry intrusion can be used as an important index of the high PV forcing. To the west of the low vortex precipitation, the upper level northerlies descend across the isentropic surface, then the dry cold advection can trigger the instable development in the mid-low troposphere. The dry intrusion enhances the low vortex precipitation. Meanwhile, because of the good agreement between the high PV at the upper level and the dry intrusion illustrated by the vapor cloud images, the dry intrusion in the vapor cloud images is the direct and clear description of the high PV forcing which provides a new insight in understanding the evolution and development of the practical weather sys- tems. Besides, both the skills of isentropic analysis and potential temperature coordinates system analysis are important to revealing the three-dimension structure of the dry intrusion.YAO XiuPing1,2,3, WU GuoXiong1, ZHAO BingKe4, YU YuBin3 & YANG GuiMing2,5 1 LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China 2 Institute of Heavy Rain, China Meteorological Administration, Wuhan 430074, China 3 China Meteorological Administration Training Center, Beijing 100081, China 4 Shanghai Typhoon Institute of China Meteorological Administration, Shanghai 200030, China 5 National Meteorological Center of the China Meteorological Administration, Beijing 100081, China 2007Science China Earth Sciences2007,50,9:11
16Sequence stratigraphic framework and distribution of depositional systems for the Paleogene in Liaodong Bay area显示文摘With a comprehensive geological and geophysical data base,the Paleogene in the Liaodong Bay area,which consists of the Kongdian,Shahejie and Donghying Formations from the base to top,was divided into 4 second-order sequences and 8 third-order sequences based on the characteristics of the se-quence boundaries. Each third-order sequence is subdivided into the lowstand,lake transgressive and highstand systems tracts. The Lowstand systems tract (LST) is mainly composed of progradational parasequence sets,while the lake transgressive systems tract (TST) largely consists of the retrograda-tional parasequence sets and the highstand systems tract (HST) is dominated by the progradational parasequence sets. The main types of depositional systems include the shallow lake,semi-deep lake,deep lake,delta,fan delta,braided fluvial delta and nearshore subaqueous fan. The braided fluvial delta and fan delta depositional systems are mainly confined to the sequences of the lower SEs4-Ek,SEs3 and SEs1+2,while the sequences of SEd3,SEd2 and SEd1 are dominated by the delta and nearshore subaqueous fan depositional systems with the latter being developed at the downthrown side of the basin-bounding fault in each sequence. The evolution of the depositional systems is always con-trolled by the paleo-tectonic setting and the ancient landform in the space and geological time. It is concluded that the most favorable reservoirs are distributed in the Liaoxi low uplift and the central Liaozhong sag.ZHU XiaoMin1,DONG YanLei1,YANG JunSheng1,ZHANG Qin1,LI DeJiang2,XU ChangGui3 & YU Shui3 1 National Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum,Beijing 102249,China 2 Research Institute of Petroleum Exploration and Development——Langfang,PetroChina,Langfang 065007,China 3 Technology Department of CNOOC Tianjin Company,Tianjin 300452,China 2008Science China Earth Sciences2008,51,S2:11
17HJ-1A HSI on-orbit radiometric calibration and validation research显示文摘The calibration experiment data at Dunhuang radiometric calibration site in October, 2008 were used to achieve the on-orbit radiometric calibration for HJ-1A hyper spectral imager (HSI). Two other field experiments data were used to validate the Dunhuang calibration results. One field experiment took place in Inner-Mongolia, China in September, 2008, and the other field experiment took place in Lake Frome, Australia in February, 2009. Finally, the ‘confidence interval of calibration error’ concept was put forward for quantitatively computing the calibration coefficient error confidence interval. The results showed that the Dunhuang calibration results in 2008 had high reliability. The confidence intervals of calibration error for all HSI channels were between 2% to 12%, which could satisfy the requirement of the HSI quantitative applications.GAO HaiLiang1,2,3*, GU XingFa1,3*, YU Tao1,3, GONG Hui1,2,3, LI JiaGuo1,2,3 & LI XiaoYing1,3 1 State Key Laboratory of Remote Sensing Science, Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University, Beijing 100101, China 2 Graduate University of Chinese Academy of Sciences, Beijing 100039, China 3 Center for National Spaceborne Demonstration, Beijing 100101, China 2010Science China(Technological Sciences)2010,53,11:10
18Combating the Fragile Karst Environment in Guizhou,China显示文摘喀斯特景观布满落水洞、洞穴、地下河及可溶性基岩,它们占据全球地表面积的25%。虽然某些喀斯特景观很吸引人,具有审美价值,大部分则是脆弱区,不适合人类居住,因为土层极其浅薄或完全无土,而且水容易流失。Zhang Baiping Xiao Fei Wu Hongzhi Mo Shenguo Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences,Datun Road 3#,Beijing 100101,China.Email: Zhu Shouqian Yu Lifei Forestry College,Guizhou University,Guiyang 550025,China.Emaih Xiong Kangning Lan Anjun Department of Resources and Environment,Guizhou Normal University,Guiyang 550001,China.Email: 2006AMBIO-人类环境杂志2006,35,2:9
19Changes in biodiversity and ecosystem function during the restoration of a tropical forest in south china显示文摘Tropical forests continue to vanish rapidly,but few long-term studies have ever examined if and how the lost forests can be restored.Based on a 45-year restoration study in south China,we found that a tropical rain forest,once completely destroyed,could not recover naturally without deliberate restoration efforts.We identified two kinds of thresholds that must be overcome with human ameliorative measures before the ecosystem was able to recover.The first threshold was imposed primarily by extreme physical conditions such as exceedingly high surface temperature and impoverished soil,while the second was characterized by a critical level of biodiversity and a landscape context that accommodates dispersal and colonization processes.Our three treatment catchments(un-restored barren land,single-species plantation,and mixed-forest stand)exhibited dramatically different changes in biodiversity and ecosystem functioning over 4 decades.The mixed forest,having the highest level of biodiversity and ecosystem functioning,possesses several major properties of tropical rain forest.These findings may have important implications for the restoration of many severely degraded or lost tropical forest ecosystems.REN Hai,LI ZhiAn,SHEN WeiJun,YU ZuoYue,PENG ShaoLin,LIAO ChongHui,DING MingMao & WU JianGuo 1 South China Botanical Garden,Chinese Academy of Sciences,Guangzhou 510650,China 2 Institute of Ecology and Evolution,Zhongshan University,Guangzhou 510275,China 3 Guangdong Institute of Entomology,Guangzhou 510275,China 4 School of Life Sciences and Global Institute of Sustainability,Arizona State University,Tempe,AZ 85287,USA 2007Science China(Life Sciences)2007,50,2:9
20Back analysis of mechanical parameters of roller compacted concrete dam显示文摘In view of the diversity and complexity of mechanical parameters of roller compacted concrete dam(RCCD),the uniform design method,partial least-squares regression(PLS)and least squares support vector machine(LSSVM)were applied to the back analysis of RCCD with the use of the complex nonlinear relationship between dam mechanical parameters and dam displacements.During the process of back analysis,the initial samples of parameters were designed with uniform design method.Then,a transversely isotropic model of RCCD was established by MSC.Marc software.Through this model,training samples of LSSVM model could be obtained.And then,the complex nonlinear relationship between relative values of hydraulic components of dam displacements and mechanical parameters was established.Finally,actual relative values of dam hydraulic components are isolated from the measured data of dam displacements by using PLS.By inputting the isolated relative values into LSSVM model,the back analysis values of RCCD mechanical parameters can be obtained.The example analysis showed that mechanical parameters obtained by the above-mentioned back analysis method are reasonable,and the back analysis method is feasible.GU ChongShi 1,2,3,LI Bo 1,XU GuangLei 4 &YU Hong 1,2,3 1 State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering,Hohai University,Nanjing 210098,China 2College of Water Conservancy Hydropower,Hohai University,Nanjing 210098,China 3National Engineering Research Center of Water Resources Engineering Safety,Efficient Utilization and Nanjing 210098,China 4 Nanjing Hydraulic Research Institute,Nanjing 210029,China 2010Science China(Technological Sciences)2010,53,3:8
返回顶部 每页显示:
共9页 首页 上一页 第1页 下一页 末页 /9 跳转

网站首页 | 关于我们 | 联系我们 | 产品服务 | 客服中心 | 广告服务 | 版权声明 | 网站联盟 | 友情链接 | 售卡网点

版权所有© 渝B2-20050021-1 渝公网安备 50019002500403号 违法和不良信息举报中心

互联网出版许可证 新出网证(渝)字10号 全国400电话 - 免长途话费