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37篇 您的检索式:作者名="Qingfeng Ma"
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1Climatic and lake environmental changes in the Serling Co region of Tibet over a variety of timescales显示文摘The Serling Co region is located at the transitional zone of the interaction between the Indian monsoon and the westerlies over the Tibetan Plateau. The Serling Co lake covers a water area of2,389 km2(June 2017) in a 45,530 km2drainage basin. Under the dramatic hydro-meteorological changes on the Tibetan Plateau in recent decades, and complex hydrological compositions of rivers and lakes in the basin, the lake area expanded by 43%, from1,667 km2in 1976, to 2,389 km2in 2017 (1)In 2014 it surpassed Nam Co as the largest lake on the Tibetan Plateau [2], and exerts significant effect on regional environmental conditions.Liping Zhu Junbo Wang Jianting Ju Ning Ma Yinsheng Zhang Chong Liu Boping Han Linshan Liu Mingda Wang Qingfeng Ma 2019Science Bulletin2019,64,7:13
2Palaeoecological and palaeoenvironmental significance of someimportant spores and micro-algae in Quaternary deposits显示文摘Spores of ferns and allied plants, and micro-algae frequently occur in abundance in Quaternary deposits, but their palaeoenvironmental significance is seldom evaluated. This paper presents morphological descriptions of spores of Selaginella sinensis (Desv.) Spring, 1843 (Selaginellaceae) and Ceratopteris cf. thalictroides (L.) Brongniart, 1821 (Parkeriaceae) and the algae Pediastrum boryanum (Turpin) Meneghini, 1840, P. simplex Meyen, 1829, P. integrum N geli, 1849 (all Hydrodictyaceae), Spiniferites Mantell, 1850, emend. Sarjeant, 1970 (Spiniferitaceae) and Concentricystes Rossignal, 1962, emend. Jiabo, 1978 (systematic position unclear), and discusses their occurrence in mostly Quaternary sedimentary successions. All are closely associated with aquatic habitats. Extant Selaginella sinensis often colonizes fairly wet hillsides and gaps between rocks, and shady sides of ravines and slopes; it is also found within thickets of trees and shrubs (boscages) and in forests with calcareous soils. Ceratopteris thalictroides, Pediastrum and Concentricystes inhabit freshwater lakes and both natural and artificial wetlands, such as paddy fields and ditches. Spiniferites is a salt-water genus and usually associated with the marine realm. Fossil and subfossil representatives of all of these taxa can be useful proxies of biodiversity and, therefore, also important for determining environmental conditions during the Quaternary period.TANG LingYu MAO LiMi Lü XinMiao MA QingFeng ZHOU ZhongZe YANG ChunLei KONG ZhaoChen BATTEN David J 2013Chinese Science Bulletin2013,58,25:9
3An experimental and numerical study on the charring rate of timber beams exposed to three-side fire显示文摘To investigate the charring rate of timber beams exposed to three-side fire, a total of fifteen new and used Douglas-Fir timber beams in four groups exposed to three-side fire were experimentally studied, together with the finite element analyses of the temperature distribution in the beam section. The durations of fire exposure were 0 (on a test piece), 10, 15, 20 and 30 min, according to the ISO 834 standard fire curve. The charring depth of each timber beam was calculated by averaging the values at one-third and two-thirds along each cross section to give the charring rate of timber beams. It was found that the timber beam's charring rate reduces as the duration of fire exposure increases and the vertical charring rate is slightly higher than the horizontal one. The areas of beam sections reduce due to charring and the strength and stiffness of the pyrolysis layer near the charring edge decrease owing to the high-temperature. The average horizontal and vertical charring rates are 0.98 and 1.08 mm/min, respectively. To take into account the difference between the test furnace temperature curve and the ISO 834 stand- ard fire curve, some corrections were made for these data to yield the solution for charring rate. With the help of the finite element software ANSYS, the temperature distribution of the wood's cross-section was analyzed. The longer the exposure time is, the greater the effect of density will impose on the distribution of temperature, but the moisture content has no effect.ZHANG Jin LIU ZengHui XU YiXiang MA ShuWei XU QingFeng 2012Science China(Technological Sciences)2012,55,12:8
4Pollen-inferred Holocene vegetation and climate histories in Taro Co,southwestern Tibetan Plateau显示文摘A 310-cm-long sediment core,covering the last10,200 years,was collected from Taro Co on the southwestern Tibetan Plateau and analyzed for pollen,grain size and total inorganic carbon content.The pollen data showed that vegetation changed from alpine steppe to alpine meadow during 10,200–8,900 cal a BP,to alpine steppe dominated by Artemisia during 8,900–7,400 cal a BP,to alpine meadow during 7,400–3,300 cal a BP and to alpine steppe after 3,300 cal a BP.Correspondingly,the pollen,grain size and total inorganic carbon content results revealed climatic change in this area over four stages.The initial stage was from 10,200 to 8,900 cal a BP,during which the climate changed from cold-dry to warm-humid.The second stage(8,900–7,400 cal a BP)was characterized by a warm and dry climate.However,at approximately7,400 cal a BP,the climate began to become cold and humid,which continued until 3,300 cal a BP.The last stage,from 3,300 cal a BP to present,was characterized as cold and increasingly arid.Climatic events of the early and mid-late Holocene showed that the area was significantly affected by the westerlies.However,the mid-Holocene climate in Taro Co was controlled by the Indian monsoon.The mid-late Holocene depositional environment record of Taro Co was very important to further elaborate the degree of influence by the westerlies or Indian monsoon.Qingfeng Ma Liping Zhu Xinmiao L Yun Guo Jianting Ju Junbo Wang Yong Wang Lingyu Tang 2014Chinese Science Bulletin2014,59,31:7
5Fargeted elimination of mutant mitochondria DNA in MELAS-iPSCs by mitoTALENs显示文摘Yi Yang Han Wu Xiangjin Kang Yanhui Liang Ting Lan Tianjie Li Tao Tan Jiangyun Peng Quanjun Zhang Geng An Yali Liu Qian Yu Zhenglai Ma Ying Lian Boon Seng Soh Qingfeng Chen Ping Liu Yaoyong Chen Xiaofang Sun Rong Li Xiumei Zhen Yang Yu Xiaoping Li Yong Fan 2018Protein & Cell2018,9,3:4
6Machine learning in nuclear physics at low and intermediate energies显示文摘Machine learning(ML)is becoming a new paradigm for scientific research in various research fields due to its exciting and powerful capability of modeling tools used for big-data processing tasks.In this review,we first briefly introduce the different methodologies used in ML algorithms and techniques.As a snapshot of many applications by ML,some selected applications are presented,especially for low-and intermediate-energy nuclear physics,which include topics on theoretical applications in nuclear structure,nuclear reactions,properties of nuclear matter,and experimental applications in event identification/reconstruction,complex system control,and firmware performance.Finally,we present a summary and outlook on the possible directions of ML use in low-intermediate energy nuclear physics and possible improvements in ML algorithms.Wanbing He Qingfeng Li Yugang Ma Zhongming Niu Junchen Pei Yingxun Zhang 2023Science China(Physics,Mechanics & Astronomy)2023,66,8:3
7Climatic significance of n-alkanes and their compound-specific dD values from lake surface sediments on the Southwestern Tibetan Plateau显示文摘The content and hydrogen isotope ratios of n-alkanes extracted from recent lake surface sediments sampled from nine lakes in three different climate zones on the Southwestern Tibetan Plateau were analyzed.Values were compared with n-alkanes in plants from lake drainages,and dD values of meteoric water,lake water,and mean annual precipitation.The results showed that n-C23was predominantly derived from aquatic plants,and n-C27–n-C33from terrestrial higher plants.The average carbon chain length of n-C27–n-C33(ACL27–33)was positively correlated with the mean annual precipitation.dD values of the long-chain n-alkanes n-C29and n-C31of terrestrial origin(varying between-214%and-169%,and-226%and-185%,respectively)were inversely correlated with mean annual precipitation;but in accordance with the average annual variations in dD(OIPC),dD values of n-C31were strongly related to the dD values of growing season meteoric water(R2=0.74).The large difference between dD values of n-C23of aquatic origin and n-C31(an average of about 27%)demonstrates the enrichment of the lake water dD compared to precipitation,caused by strong evaporation in the semiarid–arid areas of the southwestern Tibetan Plateau.Average value of en C25 31=p(-95%)is evidently higher than the value observed in European wet regions(-128%);besides,en C31(about-116%)is constant along the study transect(SD=9),which indicates that n-C31is a useful proxy for the environment.Xing Hu Liping Zhu Yong Wang Junbo Wang Ping Peng Qingfeng Ma Jianfang Hu Xiao Lin 2014Chinese Science Bulletin2014,59,24:3
8Fifty years of Quaternary palynology in the Tibetan Plateau显示文摘Quaternary palynology in the Tibetan Plateau(TP)was initiated in the 1960s to meet the needs of economic development in western China.Pollen analysis was conducted for the first time on a 200-m long core of Quaternary lacustrine sediments taken from the main body of the TP in order to study pollen assemblages as well as vegetation and climate changes of glacial(cold)/interglacial(warm)periods.Pollen analysis of alpine snow and ice began at the first scientific expedition to the TP in the 1970s.After the 1980s,a series of international collaborative programs were carried out under Sino-French,Sino-German,Sino-Australian,and Sino-American cooperation,marking the integration of Chinese Quaternary palynology society with the international community.New methods for Quaternary palynology were gradually promoted and applied,changing the vegetational and climatic interpretation of Quaternary palynology from qualitative to quantitative.Since the 1990s,many palynologists have carried out extensive Quaternary palynological studies on fossil pollen sites of more than 60 lakes/sections and alpine glaciers in the TP to discuss the spatiotemporal vegetation changes and climatic and environmental evolution of the TP since the Pleistocene.Over the past half-century,Quaternary palynology in the TP has contributed to the establishment of the Chinese Quaternary pollen database and the study of vegetation and climate evolution since the Last Glacial Maximum(LGM)in the TP.Currently available pollen records revealed the spatial and temporal distribution of vegetation in the TP since the LGM,exhibiting expansions and shrinkages of forest,meadow,grassland and desert in different periods such as the LGM,the last deglaciation,and Holocene optimum period.The paleomonsoon reflected by paleovegetation since the LGM has undergone the changes of weak-strengthening-strong-weakening but still active-shrinking,which is mainly affected by solar insolation.Lingyu TANG Caiming SHEN Houyuan LU Chuanhai LI Qingfeng MA 2021Science China Earth Sciences2021,64,11:3
9A study of peroxyacetyl nitrate at a rural site in Beijing based on continuous observations from 2015 to 2019 and the WRFChem model显示文摘Peroxyacetyl nitrate(PA N)is one of the most important photochemical pollutants and has aroused much concern in China in recent decades.However,few studies described the long-term variations in PAN in China.In this study,we continuously monitored the PAN,03 and NOx concentrations at a regional background site near Beijing from August 2015 to February 2019.Based on the observed concentrations and climate data,w e analyzed the seasonal PAN variations.The results revealed that the monthly mean PAN concentration ranged from 0.33-2.41 ppb,with an average value of 0.94 ppb.The PAN concentration exhibited a distinct seasonal variation,with high values in spring and low values in winter.After analyzing the corresponding meteorological data,we found that stronger ultraviolet(UV)radiation,a relatively longer lifetime and a higher background PAN concentration contributed to the high PAN concentrations in spring.In addition,with the utilization of the WRF-Chem(Weather Research and Forecasting with Chemistry)model,the cause of the extremely high PAN concentration in spring 2018 wa s determined.The model results demonstrated that an anomalously low pressure and the southwesterly winds in northern China might be the main causes of the increased PAN concentration in Beijing and its surrounding area in spring 2018.Yulu Qiu Zhiqiang Ma Weili Lin Weijun Quan Weiwei Pu Yingruo Li Liyan Zhou Qingfeng Shi 2020Frontiers of Environmental Science & Engineering2020,14,4:3
10Association of the vascular endothelial growth factor (VEGF) gene single-nucleotide polymorphisms with osteosarcoma susceptibility in a Chinese population显示文摘Zhen Wang Peng Wen Xiaojun Luo Xiaomin Fang Qingfeng Wang Feng Ma Jinhan Lv 2014Tumor Biology2014,,4:1
11A joint call for actions to advance taxonomy in China显示文摘Taxonomy plays an important role in understanding the origin, evolution, and ecological functionality of biodiversity. There are large number of unknown species yet to be described by taxonomists, which together with their ecosystem services cannot be effectively protected prior to description. Despite this, taxonomy has been increasingly underrated insufficient funds and permanent positions to retain young talents. Further, the impact factordriven evaluation systems in China exacerbate this downward trend, so alternative evaluation metrics are urgently necessary. When the current generation of outstanding taxonomists retires,there will be too few remaining taxonomists left to train the next generation. In light of these challenges, all co-authors worked together on this paper to analyze the current situation of taxonomy and put out a joint call for immediate actions to advance taxonomy in China.Chaodong Zhu Arong Luo Ming Bai Michael COrr Zhonge Hou Siqin Ge Jun Chen Yibo Hu Xuming Zhou Gexia Qiao Hongzhi Kong Limin Lu Xiaohua Jin Lei Cai Xinli Wei Ruilin Zhao Wei Miao Qingfeng Wang Zhongli Sha Qiang Lin Meng Qu Jianping Jiang Jiatang Li Jing Che Xuelong Jiang Xiaoyong Chen Lianming Gao Zongxin Ren Chunlei Xiang Shixiao Luo Donghui Wu Dong Liu Yanqiong Peng Tao Su Chenyang Cai Tianqi Zhu Wanzhi Cai Xingyue Liu Hu Li Huaijun Xue Zhen Ye Xuexin Chen Pu Tang Shujun Wei Hong Pang Qiang Xie Feng Zhang Feng Zhang Xianjin Peng Aibing Zhang Taiping Gao Changfa Zhou Chen Shao Libin Ma Zhaoming Wei Yunxia Luan Ziwei Yin Wu Dai Cong Wei Xiaolei Huang Jingxian Liu Xiangsheng Chen Tianci Yi Zhisheng Zhang Zhulidezi Aishan Qin Li Hongying Hu 2022Zoological Systematics2022,47,3:1
12Necessary and Sufficient Conditions for the Existence ofGlobal Attractors for Semigroup and Applications 显示文摘MA Qingfeng WANG Shouhong ZHONG Chengkui 2002Indiana Univ Math J2002,51,6:1
13Development of a roll-bonded UNS N08825 alloy clad pipeline steel in Baosteel显示文摘In this study,a roll-bonded UNS N088225 alloy clad pipeline steel was investigated and developed in Baosteel. Based on the requirements of a number of potential projects,we performed a series of strict evaluations including mechanical and corrosion tests. The results show the mechanical properties and corrosion resistance of this clad steel to be excellent and to meet the requirements of all the design parameters.LIANG Xiaojun MA Tianjun FU Yanhong JIAO Sihai DING Jianhua YUAN Xiangqian WANG Baosen ZHANG Qingfeng 2017Baosteel Technical Research2017,11,1:1
14The binding epitope of sintilimab on PD-1 revealed by AbMap显示文摘PD-1 plays an important role as an immune checkpoint.Sintilimab is a newly approved PD-1 antibody for cancer immunotherapy with an unknown binding epitope on PD-1.In this study,to elucidate the molecular mechanism by which sintilimab blocks PD-1 activation,we applied Antibody binding epitope Mapping(AbMap)to identify the binding epitope of sintilimab.An epitope was successfully identified,i.e.SLAPKA,aa 127-132.By constructing a series of point mutations,the dominant residues S127,L128,A129,P130,and A132 of PD-1 were further validated by western blot analysis,biolayer interferometry,and flow cytometry.Structural analysis showed that the epitope is partially within the binding interface of PD-1 and PD-L1,and this epitope also partially overlaps with that of nivolumab and pembrolizumab.These results demonstrate that sintilimab can attenuate PD-1 activation by directly competing with the interaction between PD-1 and PD-L1 through binding with the key residues of the FG loop on PD-1.This study also demonstrates the high efficiency and accuracy of AbMap for determining the binding epitope of therapeutic antibodies.Mingliang Ma Huan Qi Chuansheng Hu Zhaowei Xu Fanlin Wu Nan Wang Danyun Lai Yang Li Hainan Zhang Hewei Jiang Qingfeng Meng Shujuan Guo Yani Kang Xiaodong Zhao Hua Li Sheng-ce Tao 2021Acta Biochimica et Biophysica Sinica2021,53,5:1
15Adsorption synergic biodegradation of high-concentrated phenolic water by Pseudomonas putida immobilized on activated carbon fiber显示文摘Xiaoshuang Ma Najun Li Jun Jiang Qingfeng Xu Hua Li Lihua Wang Jianmei Lu 2013Journal of Environmental Chemical Engineering2013,,:1
16Copper(I)-Catalyzed Intramolecular N-N Coupling of Cyclopropyl O-Acyl Ketoximes: Synthesis of Spiro-fused Pyrazolin-5-ones显示文摘一条方便催化铜的途径经由 intramolecular NN 契约形成反应从容易地可得到的 cyclopropyl O 酰 ketoximes 为代替的熔化 spiro 的 pyrazolin-5-ones 的合成被开发了。这些催化反应在优秀收益继续一个宽广范围。Zhiguo Zhang Junlong Li Guoqing Huang Kai Sun Guisheng Zhang Nana Ma Qingfeng Liu Tongxin Liu 2016Chinese Journal of Chemistry2016,34,12:1
17Molecular cytogenetic analyses of two new wheat-rye 6RL translocation lines with resistance to wheat powdery mildew显示文摘Rye(Secale cereale)is a valuable gene donor for wheat improvement,especially for its resistance to diseases.Developing rye-derived resistance sources is important for wheat breeding.In the present study,two wheat-rye derivatives,designated JS016 and JS110,were produced by crossing common wheat cultivar Yangmai 23 with Pakistani rye accession W2A.Using sequential genomic in situ hybridization(GISH)and multicolor fluorescence in situ hybridization(mc-FISH),JS016 and JS110 were identified as a T6BS.6RL translocation line and a T6BS.6BL6RL translocation line,respectively.Ten newly 6RL chromosome arm-specific markers were developed and used to confirm the 6RL translocation.The wheat 55K single-nucleotide polymorphism(SNP)array further verified the molecular cytogenetic identification results above and clarified their breakpoints at 430.9 and 523.0 Mb of chromosome 6B in JS016 and JS110,respectively.Resistance spectrum and allelism test demonstrated that JS016 and JS110 possessed novel powdery mildew resistance gene(s)that was derived from the 6RL translocation but differed from Pm20.Moreover,JS016 and JS110 had better agronomic traits than the previously reported 6RL translocation line carrying Pm20.To efficiently transfer and detect the 6RL translocation from JS016 and JS110,one 6RL-specific Kompetitive allele specific PCR(KASP)marker was developed and validated in high throughput marker-assisted selection(MAS).Shanying Zhu Haonan Du Fuyu Su Jin Wang Qingfeng Meng Tianlei Liu Rui Guo Zhaozhao Chen Huanhuan Li Wenxuan Liu Pengtao Ma Huagang He 2023The Crop Journal2023,11,2:1
18Hochschild cohomology of Beilinson algebra of exterior algebra显示文摘Let An be the Beilinson algebra of exterior algebra of an n-dimensional vector space,which is derived equivalent to the endomorphism algebra End O X(T) of a tilting complex T = Πni=0 OX(i) of coherent O X-modules over a projective scheme X = P n k.In this paper we first construct a minimal projective bimodule resolution of Λn,and then apply it to calculate k-dimensions of the Hochschild cohomology groups of Λn in terms of parallel paths.Finally,we give an explicit description of the cup product and obtain a Gabriel presentation of Hochschild cohomology ring of Λn.As a consequence,we provide a class of algebras of finite global dimension whose Hochschild cohomology rings have non-trivial multiplicative structures.XU YunGe ZHANG Chao MA XiaoJing HU QingFeng 2012Science China Mathematics2012,55,6:1
19Necessary and sufficient conditions for the existence of global attractor for semigroup and application显示文摘Ma Qingfeng Wang Shouhong Zhong Chengkui 2002Indiana University Mathematics Journal2002,51,:1
20Variation in Sunshine Duration and Related Aerosol Influences at Shangdianzi GAW Station, China: 1958–2021显示文摘Sunshine duration(SD) is adopted widely to study global dimming/brightening. However, long-term simultaneous measurements of SD and closely related impact factors require further analysis to elucidate how and why SD has varied during the past decades. In this study, a long-term(1958–2021) SD data series obtained from the Shangdianzi Global Atmosphere Watch(GAW) station in China was analyzed to detect linear trends, climatic jumps, and climatic periods in SD using linear fitting, the Mann–Kendall trend test, and the continuous wavelet transform method. Annual SD exhibited steady dimming(-67.3 h decade-1) before 2010, followed by a period of brightening(189.9 h decade-1)during 2011–2020. An abrupt jump in annual SD occurred in 1995, and the annual SD anomaly exhibited significant oscillation with ~3-yr periodicity during 1960–1978. Partial least squares analysis revealed that annual SD anomaly was associated with variations in relative humidity, gale days, cloud cover, and black carbon(BC). Further analysis of the clear-sky daily sunshine percentage(DSP) and simultaneous measurements of aerosol properties, including aerosol optical depth, aerosol extinction coefficient, single scattering albedo(SSA), BC, and total suspended particulates, suggested that variation in DSP was affected primarily by aerosol scattering and absorption. Furthermore, the hourly clear-sky SD at high aerosol loading was approximately 60% and 56% of that at middle and low aerosol loadings, respectively. The pattern of diurnal variation in clear-sky hourly SD, as well as the actual values, can be affected by the fine particulate concentration, aerosol extinction coefficient, and SSA.Weijun QUAN Zhiqiang MA Ziming LI Xiaolan LI Yingruo LI Xiangao XIA Huaigang ZHOU Hujia ZHAO Zhenfa WANG Weiwei PU Fan DONG Di HE Liyan ZHOU Qingfeng SHI Wenyan WANG Fang JIA 2023Journal of Meteorological Research2023,37,4:0
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