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28篇 您的检索式:作者名="XU Chunhai"
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1Regional eco-efficiency evaluation and spatial pattern analysis of the Yangtze River Economic Zone显示文摘The environmental ecology of the Yangtze River Economic Zone(YREZ)faces ecological function decline,deterioration and degradation under intense human activities,long-term development and utilization and its economy has developed rapidly over recent decades.Eco-efficiency is considered as a measure of coordinated development of economy,resources,environment and ecology,and is currently considered a very important issue.In this paper,based on the slack-based measure and data envelope analysis model,we take 129 prefecture-level cities of the YREZ as the study unit and measure the eco-efficiency of the YREZ in 2000,2005,2010 and 2015,which considers undesired output.The evaluation of the status quo of the regional eco-efficiency development was carried out at provincial,prefectural and city scales.The spatial autocorrelation test model and standard deviation ellipse were used to analyze the spatially distributed characteristics and the evolutionary regularity of eco-efficiency.Our study suggested that the eco-efficiency value varied significantly at different spatiotemporal scales and the overall distribution presented an'N-shaped'pattern,the value is the largest downstream and the smallest upstream.Regional eco-efficiency presented certain volatility in growth and a clear spatial positive agglomeration trend from 2000 to 2015.The spatial distribution of each agglomeration area was also significantly different,forming some high-high agglomeration areas at the center of the shaft with Shanghai and surrounding cities,and some low-low agglomeration areas at the center with middle reaches and upstream cities.The low-high over-aggregation and high-low polarization clusters were fewer.At the same time,with the change of the research period,the degree of positive agglomeration became increasingly pronounced and the eco-efficiency gap of the neighborhoodunit reduced.The regional eco-efficiency value of the YREZ presented a spatial distribution pattern in the northeast-southwest axis and the evolutionary pattern of the regional eco-efficiency similarly showed a northeast-southwest orientation.HA Lin TU Jianjun YANG Jianping XU Chunhai PANG Jiaxing LU Debin YAO Zuolin ZHAO Wenyu 2020Journal of Geographical Sciences2020,30,7:8
2Dependability analysis of the data communication system in train control system显示文摘Communication based train control (CBTC) system is based on mobile communication and overcomes fixed blocks in order to increase track utilization and train safety. The data communication system (DCS) between trains and wayside equipment is a crucial factor for the safe and efficient operation of CBTC system. The dependability under various transmission conditions needs to be modeled and evaluated. In this paper,a stochastic reward net (SRN) model for DCS based IEEE 802.11 standard was developed,which captures all relevant failure and failure recovery behavior system aspects in a concise way. We compared the reliability,availability for DCS with and without access point (AP) and antenna redundant configuration. We also quantitatively evaluated and compared the frame loss probability for three DCS configurations with different train velocities and train numbers in one radio cell. Fixed-point iteration was adopted to simplify the analysis. Numerical results showed the significant improvement of the reliability,availability and the frame loss probability index for the full redundant configuration.XU TianHua TANG Tao GAO ChunHai CAI BaiGen 2009Science China(Technological Sciences)2009,52,9:7
3Detection of infrared photons with a superconductor显示文摘A superconductor single photon detector based on NbN nanowire was fabricated using electron beam lithography (EBL) and reactive ion etching (RIE) for infrared photon detection. When biased well below its critical current at 4.2 K, NbN nanowire is very sensitive to the incident photons. Typical telecommunication photons with a wavelength of 1550 nm were detected by this detector. Data analysis indicates the repeating rate of the device with 200 nm NbN nanowire may be up to 100 MHz, and the quantum efficiency is about 0.01% when biased at 0.95Ic.ZHANG LaBao ZHONG YangYin KANG Lin CHEN Jian JI ZhengMing XU WeiWei CAO ChunHai 2009Chinese Science Bulletin2009,54,12:6
4Design and fabrication of superconducting HEB mixer显示文摘This paper describes the design and fabrication of superconducting hot electron bolometer (HEB) mixer based on ultra-thin superconducting NbN films. The high quality films were epitaxially grown on high resistance Si substrates. The device was fabricated by magnetron sputtering, electron beam lithography (EBL), reactive ion etching (RIE), lithography, and so on. The device's resistance-tempera-ture (R-T) curves and current-voltage (I-V) curves were studied. The results of THz response of the device are presented. Y-factor technique was used to measure the device's noise temperature. When the device was irradiated with a laser radiation of 2.5 THz, the obtained lowest noise temperature of the device was 2213 K.WANG JinPing LI YangBin KANG Lin WANG Yu ZHONG YangYin LIANG Min CHEN Jian CAO ChunHai XU WeiWei WU PeiHeng 2009Chinese Science Bulletin2009,54,12:5
5Character and fabrication of Al/Al_2O_3/Al tunnel junctions for qubit application显示文摘The superconductive Josephson junction is the key device for superconducting quantum computation. We have fabricated Al/Al2O3/Al tunnel junctions using a double angle evaporation method based on a suspended shadow mask. The Al2O3 junction barrier has been formed by introducing pure oxygen into the chamber during the fabrication process. We have adjusted exposure conditions by changing either the oxygen pressure or the oxidizing time during the formation of tunnel barriers to control the critical current density Jc and the junction specific resistance Rc. Measurements of the leakage in Al/Al2O3/Al tunnel junctions show that the devices are suitable for qubit applications.SHEN DanDan ZHU Ran XU WeiWei CHANG JunJie JI ZhengMing SUN GuoZhu CAO ChunHai CHEN Jian 2012Chinese Science Bulletin2012,57,4:4
6A highly sensitive chemiluminescence sensor for detecting mercury(Ⅱ) ions: a combination of Exonuclease Ⅲ-aided signal amplification and graphene oxide-assisted background reduction显示文摘In this paper, we report a highly sensitive chemiluminescence(CL) sensor for Hg2+ ions based on thymine-Hg2+-thymine(T-Hg2+-T) coordination chemistry. We designed a thymine rich oligonucleotide as a capture probe and a signal probe that includes two functional domains: a horseradish peroxidase-mimicking DNAzyme domain for the generation of CL, and a recognition domain. Graphene oxide(GO) was introduced to adsorb the signal probe via π-π interaction, which brought the DNAzyme domain and GO into close proximity and quenches CL. In the presence of Hg2+ ions, the coordination of Hg2+ with the capture probe yielded a hairpin complex, triggers cascaded strand displacement reactions and Exonuclease III-assisted signal amplifications. As a result, accumulated amounts of DNAzyme were generated and released from GO, leading to an enhanced CL signal. This strategy combines enzyme-based signal amplification and GO as a background reducer, leads to a limit of detection(LOD) of 2 nmol/L. This simple detection system provides a label-free yet sensitive approach for detection of Hg2+ ions.Yang Tian Yue Wang Yan Xu Yang Liu Di Li Chunhai Fan 2015Science China Chemistry2015,58,3:3
760-year changes and mechanisms of Urumqi Glacier No.1 in the eastern Tianshan of China,Central Asia显示文摘Worldwide examination of glacier change is based on detailed observations from only a small number of glaciers.The ground-based detailed individual glacier monitoring is of strong need and extremely important in both regional and global scales.A long-term integrated multi-level monitoring has been carried out on Urumqi Glacier No.1(UG1)at the headwaters of the Urumqi River in the eastern Tianshan Mountains of Central Asia since 1959 by the Tianshan Glaciological Station,Chinese Acamedey of Sciences(CAS),and the glaciological datasets promise to be the best in China.The boundaries of all glacier zones moved up,resulting in a shrunk accumulation area.The stratigraphy features of the snowpack on the glacier were found to be significantly altered by climate warming.Mass balances of UG1 show accelerated mass loss since 1960,which were attributed to three mechanisms.The glacier has been contracting at an accelerated rate since 1962,resulting in a total reduction of 0.37 km2 or 19.3%from 1962 to 2018.Glacier runoff measured at the UG1 hydrometeorological station demonstrates a significant increase from 1959 to 2018 with a large interannual fluctuation,which is inversely correlated with the glacier's mass balance.This study analyzes on the changes in glacier zones,mass balance,area and length,and streamflow in the nival glacial catchment over the past 60 years.It provides critical insight into the processes and mechanisms of glacier recession in response to climate change.The results are not only representative of those glaciers in the Tianshan mountains,but also for the continental-type throughout the world.The direct observation data form an essential basis for evaluating mountain glacier changes and the impact of glacier shrinkage on water resources in the interior drainage rivers within the vast arid and semi-arid land in northwestern China as well as Central Asia.ZhongQin Li HuiLin Li ChunHai Xu YuFeng Jia FeiTeng Wang PuYu Wang XiaoYing Yue 2020Research in Cold and Arid Regions2020,12,6:2
8Elimination of a Retrotransposon for Quenching Genome Instability in Modern Rice显示文摘Transposable elements(TEs)constitute the most abundant portions of plant genomes and can dramatically shape host genomes during plant evolution.They also play important roles in crop domestication.However,whether TEs themselves are also selected during crop domestication has remained unknown.Here,we identify an active long terminal repeat(LTR)retrotransposon,HUO,as a potential target of selection during rice domestication and breeding.HUO is a low-copy-number LTR retrotransposon,and is active under natural growth conditions and transmitted through male gametogenesis,preferentially inserting into genomic regions capable of transcription.HUO exists in all wild rice accessions and about half of the archaeological rice grains(1200–7000 years ago)and landraces surveyed,but is absent in almost all modern varieties,indicating its gradual elimination during rice domestication and breeding.Further analyses showed that HUO is subjected to strict gene silencing through the RNA-directed DNA methylation pathway.Our results also suggest that multiple HUO copies may trigger genomic instability through altering genome-wide DNA methylation and small RNA biogenesis and changing global gene expression,resulting in decreased disease resistance and yield,coinciding with its elimination during rice breeding.Together,our study suggests that negative selection of an active retrotransposon might be important for genome stability during crop domestication and breeding.Yu Peng Yingying Zhang Yijie Gui Dong An Junzhong Liu Xun Xu Qun Li Junmin Wang Wen Wang Chunhai Shi Longjiang Fan Baorong Lu Yiwen Deng Sheng Teng Zuhua He 2019Molecular Plant2019,12,10:2
9Terahertz narrow bandstop, broad bandpass filter using double-layer S-shaped metamaterials显示文摘In this study,double-layer S-shaped metamaterials(MMs)are analyzed by terahertz time-domain spectroscopy.These materials exhibit narrow bandstop and broad bandpass transmission properties at both horizontal and vertical electric-feld polarizations.A 117%increase in the unloaded quality factor is experimentally observed for these materials.The center frequency is approximately 0.45 THz,with a 3-dB bandwidth of 0.52 THz from 0.20 to 0.72 THz at normal incidence.The measured average insertion loss is 0.5 dB with a ripple of 1 dB.These results show that double-layer S-shaped MMs are efective in designing tunable terahertz devices.LIANG LanJu JIN BiaoBing WU JingBo ZHOU GaoChao ZHANG YongGang TU XueCou JIA Tao JIA XiaoQing CAO ChunHai KANG Lin XU WeiWei CHEN Jian 2013Science China(Information Sciences)2013,56,12:2
10Enzyme-Triggered Fluorescence Turn-on: A Probe for Specifically Imaging Ovarian-Cancer-Related γ-Glutamyltranspeptidase显示文摘Jie Tian Qinglong Yan Ying Zhu Jichao Zhang Jiao Li Ben Shi Ge Xu Chunhai Fan Chunchang Zhao 2017Chinese Journal of Chemistry2017,35,11:2
11Volatile oil analysis and quality control of Chinese traditional medicines显示文摘RUAN Chunhai XU Guowang LU Xin 2003Chromatographia2003,57,1:1
12Efficient Extractive Desulfurization of Fuel Oils Using N-Pyrrolidone/Alkylphosphate-Based Ionic Liquids显示文摘Four BrØsted acid ionic liquids(ILS)[MMP][DMP],[MEP][DEP],[HMP][DMP]and[HEP][DEP]were syn-thesized and used as extractants for desulfurization of aromatic sulfur compounds in model oil.The mutual solubil-ity of four ILs were investigated.The extraction equilibrium of four ILs could be reached in as soon as 5 min and the extraction capability followed the order[MMP][DMP]>[MEP][DEP]>[HEP][DEP]>[HMP][DMP].The S extraction showed the highest efficiency under the conditions of 30℃,30 min and 1∶1(V/V)IL∶oil.Under the optimal condition,70.9%of thiophene(TS),76.9%of benzothiophene(BT)and 87.5%of dibenzothiophene(DBT)in n-octane could be efficiently removed by[MMP][DMP].The multiple extraction and regeneration performance of[MMP][DMP]for TS was also investigated and the results were satisfying.These results suggest that[MMP][DMP]has the best extraction capability and can serve as a promising solvent for extractive desulfurization of fuel oils.Chunhai Liu Qihui He Zheng Zhang Yangyang Su Renfu Xu Baixing Hu 2014Chinese Journal of Chemistry2014,32,5:1
13Multi-decadal variations in glacier flow velocity and the influencing factors of Urumqi Glacier No.1 in Tianshan Mountains, Northwest China显示文摘Urumqi Glacier No. 1 is a representative glacier in the inland areas of Central Asia and is the only Chinese reference glacier in the World Glacier Monitoring Service. In this study, we explored multi-decadal variations in the flow velocity of the glacier and the influencing factors based on continuous field observations and path coefficient analysis. Results show that the glacier flow velocity decreased from 5.5 m/a in 1980/1981 to 3.3 m/a in 2010/2011. The annual variation in the direction of glacier flow velocity in the western branch and eastern branch was less than 1°–3°, and the change of glacier flow velocity in the western branch was more dramatic than that in the eastern branch. Glacier flow velocity was influenced by glacier morphology(including glacier area, glacier length, and ice thickness), glacier mass balance and local climate conditions(air temperature and precipitation), the glacier morphology being the leading factor. The long-term flow velocity data set of Urumqi Glacier No. 1 contributes to a better understanding of glacier dynamics within the context of climatic warming.WANG Puyu LI Zhongqin XU Chunhai XING Wucheng ZHOU Ping ZHANG Hui 2017Journal of Arid Land2017,9,6:1
14Th1 and Th2 Immune Response in Chronic Hepatitis B Patients during a Long-Term Treatment with Adefovir Dipivoxil显示文摘Yanfang Jiang Zhenhua Ma Guijie Xin Hongqing Yan Wanyu Li Huining Xu Chunhai Hao Junqi Niu Pingwei Zhao Dennis Daniel Taub 2010Mediators of Inflammation2010,,:1
15Region-wide glacier area and mass budgets for the Shaksgam River Basin,Karakoram Mountains,during 2000–2016显示文摘The Karakoram Mountains are well known for their widespread surge-type glaciers and slight glacier mass gains.On the one hand,glaciers are one of the sensitive indicators of climate change,their area and thickness will adjust with climate change.On the other hand,glaciers provide freshwater resources for agricultural irrigation and hydroelectric generation in the downstream areas of the Shaksgam River Basin(SRB)in western China.The shrinkage of glaciers caused by climate change can significantly affect the security and sustainable development of regional water resources.In this study,we analyzed the changes in glacier area from 2000 to 2016 in the SRB using Landsat TM(Thematic Mapper)/ETM+(Enhanced Mapper Plus)/OLI(Operational Land Imager)images.It is shown that the SRB contained 472 glaciers,with an area of 1840.3 km2,in 2016.The glacier area decreased by 0.14%/a since 2000,and the shrinkage of glacier in the southeast,east and south directions were the most,while the northeast,north directions were the least.Debris-covered area accounted for 8.0%of the total glacier area.We estimated elevation and mass changes using the 1 arc-second SRTM(Shuttle Radar Topography Mission)DEM(Digital Elevation Model)(2000)and the resolution of 8 m HMA(High Mountain Asia)DEM(2016).An average thickness of 0.08(±0.03)m/a,or a slight mass increase of 0.06(±0.02)m w.e./a has been obtained since 2000.We found thinning was significantly lesser on the clean ice than the debris-covered ice.In addition,the elevation of glacier surface is spatially heterogeneous,showing that the accumulation of mass is dominant in high altitude regions,and the main mass loss is in low altitude regions,excluding the surge-type glacier.For surge-type glaciers,the mass may transfer from the reservoir to the receiving area rapidly when surges,then resulting in an advance of glacier terminus.The main surge mechanism is still unclear,it is worth noting that the surge did not increase the glacier mass in this study.WANG Panpan LI Zhongqin XU Chunhai WANG Puyu 2021Journal of Arid Land2021,13,2:1
16Development of a novel nitrite amperometric sensor based on poly( toluidine blue)film electrode显示文摘YANG Chunhai XU Junhui HU Shengshui 2007J Solid State Electrochem2007,11,4:1
17Nucleic acids analysis显示文摘Nucleic acids are natural biopolymers of nucleotides that store, encode, transmit and express genetic information, which play central roles in diverse cellular events and diseases in living things. The analysis of nucleic acids and nucleic acids-based analysis have been widely applied in biological studies, clinical diagnosis, environmental analysis, food safety and forensic analysis.During the past decades, the field of nucleic acids analysis has been rapidly advancing with many technological breakthroughs.In this review, we focus on the methods developed for analyzing nucleic acids, nucleic acids-based analysis, device for nucleic acids analysis, and applications of nucleic acids analysis. The representative strategies for the development of new nucleic acids analysis in this field are summarized, and key advantages and possible limitations are discussed. Finally, a brief perspective on existing challenges and further research development is provided.Yongxi Zhao Xiaolei Zuo Qian Li Feng Chen Yan-Ru Chen Jinqi Deng Da Han Changlong Hao Fujian Huang Yanyi Huang Guoliang Ke Hua Kuang Fan Li Jiang Li Min Li Na Li Zhenyu Lin Dingbin Liu Juewen Liu Libing Liu Xiaoguo Liu Chunhua Lu Fang Luo Xiuhai Mao Jiashu Sun Bo Tang Fei Wang Jianbin Wang Lihua Wang Shu Wang Lingling Wu Zai-Sheng Wu Fan Xia Chuanlai Xu Yang Yang Bi-Feng Yuan Quan Yuan Chao Zhang Zhi Zhu Chaoyong Yang Xiao-Bing Zhang Huanghao Yang Weihong Tan Chunhai Fan 2021Science China Chemistry2021,64,2:1
18Novel TiC/Ti Open Cellular Foams Prepared by a Modified Sponge-coating Method Using High Frequency Induction Heating Process显示文摘A new kind of open cellular foam material with three dimensionally interconnected TiC/Ti struts was prepared by a two-step sponge-coating and high frequency induction heating process.The microstructure,composition and compression strength of the prepared TiC/Ti foam materials were characterized.It was confirmed that the incorporation of Ti into TiC resulted in an inter-bonded Ti-TiC-Ti layered structure in the struts,which enhanced the plasticity of the composite foam materials.Yong Gao Xingxiang Xu Zhenming Yang Junqi Zhang Chunhai Jiang Jinsong Zhang 2013Journal of Materials Science & Technology2013,29,4:1
19Preparation and properties of phosphorous–nitrogen containing UV-curable polymeric coatings based on thiol–ene click reaction显示文摘Chunhai Liu Tingcheng Li Junheng Zhang Sufang Chen Zhicai Xu Aiqing Zhang Daohong Zhang 2016Progress in Organic Coatings2016,,:1
20High-precision measurements of the inter-annual evolution for Urumqi Glacier No.1 in eastern Tien Shan,China显示文摘High-precision measuring of glacier evolution remains a challenge as the available global and regional remote sensing techniques cannot satisfactorily capture the local-scale processes of most small-and medium-sized mountain glaciers.In this study,we use a high-precision local remote sensing technique,long-range terrestrial laser scanning(TLS),to measure the evolution of Urumqi Glacier No.1 at an annual scale.We found that the dense point clouds derived from the TLS survey can be used to reconstruct glacier surface terrain,with certain details,such as depressions,debris-covered areas,and supra-glacial drainages can be distinguished.The glacier experienced pronounced thickness thinning and continuous retreat over the last four mass-balance years(2015−2019).The mean surface slope of Urumqi Glacier No.1 gradually steepened,which may increase the removal of glacier mass.The glacier was deeply incised by two very prominent primary supra-glacial rivers,and those rivers presented a widening trend.Extensive networks of supra-glacial channels had a significant impact on accelerated glacier mass loss.High-precision measuring is of vital importance to understanding the annual evolution of this type of glacier.ChunHai Xu ZhongQin Li JianXin Mu PuYu Wang FeiTeng Wang 2021Research in Cold and Arid Regions2021,13,6:0
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