检索结果-南通市图书馆

A 12-bit multichannel ADC for pixel detectors in particle physics and nuclear imaging

在线全文

学校读者我要写书评

暂无评论

Science china(Technological sciences) 2010年第5期53卷 1208-1214页

作者： WEI Wei1,2,3.WANG Zheng1,3.& ZHAO JingWei1,3.1 institute of High Energy Physics,chinese academy of {3.,Beijing 100049,china 2 Graduate University of chinese academy of sciences,Beijing 100049,china 3.Key Lab of Nuclear Detection Technology and Nuclear Electronics of chinese academy of sciences,Beijing 100049,china institute of High Energy Physics Chinese Academy of Sciences Beijing China Graduate University of chinese academy of sciences Beijing China Key Lab of Nuclear Detection Technology and Nuclear Electronics of chinese academy of sciences Beijing China

Modern pixel detectors in nuclear and particle physics experiments and also in nuclear imaging,starve for highly integrated application specified integrated circuit(ASIC),whereas in china the study of ASIC still stays far away from practical *** lack of ASIC strictly limits the research and development of domestic high energy physics field.A 12-bit multichannel ADC designed for high density readout is introduced as a major candidate for solution.A precise model is discussed and the simulation fully agrees with the model,which indicates a key principle of *** is performed according to the given rule,and novel layout techniques are carried *** results in all aspects are also obtained,showing an excellent real performance,which satisfies the practical requirement.

关键词： application specified integrated circuit high density readout Wilkinson ADC multi-channel ADC

Chronology of Holocene lacustrine sediments in Co Ngoin, central Tibetan Plateau

在线全文

学校读者我要写书评

暂无评论

Science china Earth sciences 2006年第9期49卷 991-1001页

作者： WU Yanhong1, WANG Sumin1& HOU Xinhua1,3.1. Key Laboratory of Lake Sedimentation and Environment, Nanjing institute of Geography and Limnology, chinese academy of sciences, Nanjing 210008, china 2. institute of Tibetan Plateau Research, chinese academy of sciences, Beijing 10085, china 3. Graduate University of chinese academy of sciences, Beijing 10003., china Key Laboratory of Lake Sedimentation and Environment Nanjing Institute of Geography and Limnology Chinese Academy of Sciences Nanjing China institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China Graduate University of chinese academy of sciences Beijing China

Chronology is the basis for using lacustrine sediments to reconstruct the history of en-vironmental change. Radioactive-nuclides such as 14C, 210Pb and 13.Cs dating are mainly used to establish the chronology for recent several ten thousand years. Because of being mixed with “dead carbon”, the measured 14C age is always older than the actual age which is recognized as “reservoir effect”. Cs is a kind of active metal element, and easy to migrate vertically in the sediment that leads to the error of the time marker. 210Pb dating should make sure to select CIC model or CRS model. On the Tibetan Plateau, most of the lakes are alkaline closed lake where Cs is more moveable in the sediment and the reservoir effect caused by “dead carbon” on 14C dating is stronger. Based on the analysis on results of 14C, 210Pb and 13.Cs of the lacustrine sediments from Co Ngoin, central Tibetan Plateau, we use the simple regression method to re-calculate the 14C calendar ages, and establish the time sequence for cores CE-1 and CE-2 with result of 210Pb CRS model for the upper 3. cm and re-calculated 14C calendar age for sediments bellow 3. cm. Since 1400 cal. a BP, sedimentation inter-rupted for more than 1000 years. According to this time sequence, variations of environmental proxies confidently reflect the major climatic events in Holocene.

关键词： 14C, 210Pb and 13.Cs, chronology, lacustrine sediments, climatic event, Co Ngoin, central Tibetan Plateau.

Impact of land-use change on hydrological processes in the Maying River basin, china

在线全文

学校读者我要写书评

暂无评论

Science china Earth sciences 2006年第10期49卷 1098-1110页

作者： WANG Genxu1,3. ZHANG Yu2, LIU Guimin2 & CHEN Lin3.1. institute of Mountain Hazards and Environment, chinese academy of sciences, Chengdu 610041, china 2. Cold and Arid Regions Environmental and Engineering Research institute, chinese academy of sciences, Lanzhou 73.000, china 3. Resource and Environment School, Lanzhou University, Lanzhou 73.000, china institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu China Resource and Environment School Lanzhou University Lanzhou China Cold and Arid Regions Environmental and Engineering Research institute Chinese Academy of Sciences Lanzhou China

Since the 1960s, dramatic changes have taken place in land-use patterns characterized by the persistent expansion of cultivated land and a continuous decrease in natural woodland and grassland in the arid inland river basins of china. It is very important to assess the effects of such land-use changes on the hydrological processes so vital for water resource management and sustainable development on the catchment scale. The Maying River catchment, a typical arid inland watershed located in the middle of the Hexi Corridor in northwest china, was the site chosen to investigate the hydrological responses to land-use changes. The annual runoff, base flow, maximum peak flow, and typical seasonal runoff in both spring and autumn flood periods were selected as the variables in the hydrological processes. Statistical-trend analysis and curvilinear regression were utilized to detect the trends in hydrological variables while eliminating the climatic influence. The relationship between cultivated land-use and hydrological variables was analyzed based on four periods of land-use variation data collected since 1965. A runoff model was established composed of two factors, i.e., cultivated land use and precipitation. The impact of land use changes, especially in the large ar- eas of upstream woodland and grassland turned into cultivated lands since 1967, has resulted in a mean annual runoff decrease of 28.12%, a base flow decline of 3..3.%, a drop in the maximum peak discharge of 3..77%, and mean discharge decreases in spring and autumn of 3..05% and 24.87% respectively, of which the contribution of cultivated land expansion to the influence of annual runoff amounts to 77%-80%, with the contribution to the influence of spring discharge being 73.-81%, and that to the influence of base flow reaching 62%-65%. Thus, a rational regulation policy of land use patterns is vitally important to the sustainable use of water resources and the proper development of the entire catchment.

关键词： land-use change, arid inland river catchment, hydrological process, impact, Maying River.

Chronic morphine exposure induces degradation of receptive field properties of LGN cells in cats

在线全文

学校读者我要写书评

暂无评论

Acta Pharmacologica Sinica 2005年第9期26卷 1034-1038页

作者： Li-hua HE~2 Guang-xing LI~2 Xiang-mi LI~2 Yi-feng ZHOU~(2,3.4)2 hefei National Laboratory for Physical sciences at Microscale and School of Life Science,University of Science and Technology of china,hefei 23.027,china 3.Laboratory of Visual Information Processing,institute of Biophysics,chinese academy of sciences,Beijing 100101,china hefei National Laboratory for Physical sciences at Microscale and School of Life Science University of Science and Technology of China Hefei China Laboratory of Visual Information Processing Institute of Biophysics Chinese Academy of Sciences Beijing China

Aim:To investigate the effect of chronic morphine exposure on the receptive fieldproperties of lateral geniculate nucleus(LGN)neurons in ***:Catswere injected with morphine(10 mg/kg)or saline twice daily,for 10 ***,extracellular single-unit recording techniques were used to examine the sensitivityof LGN neurons to visual stimuli in chronic morphine-treated and ***:Compared with saline-treated cats(as controls),LGN neurons inmorphine-treated cats had decreased signal-to-noise ratios(1.9 vs 3.1 ),and orien-tation and direction sensitivity(0.103.vs O.13. and 0.074 vs O.10,respectively),accompanied by significant increases in spontaneous(27.4 vs 17.5)and evokedactivity(preferred:42.2 vs 3..1;average:28.1 vs 22.3..Conclusion:Chronic mor-phine exposure can lead to the functional degradation of LGN neurons in cats,which might result from the effects of chronic morphine exposure on inhibitoryneurotransmission.

关键词： direction sensitivity orientation sensitivity signal-to-noise ratio spontaneous response evoked response

An improved method for evaluating the seasonal variability of total suspended sediment flux field in the Yellow and East china Seas

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2011年第1期26卷 1-14页

作者： PANG Chongguang~1,YU Wei~2,YANG Yang~3.and HAN Danxiu~4 institute of Oceanology,chinese academy of {3.,Qingdao 266071,china, 2 institute of Oceanology,chinese academy of {3.,Qingdao 266071,china,Graduate School of chinese academy of sciences,Beijing 10003.,china 3.institute of Oceanology,chinese academy of {3.,Qingdao 266071,china,Graduate School of chinese academy of sciences,Beijing 10003.,china 4 china University of Petroleum,Beijing 102249,china Doctor Researcher Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China Graduate School of Chinese Academy of Sciences Beijing 100039 China china University of Petroleum Beijing 102249 China

The suspended sediment flux field in the Yellow and East china Seas(YECS) displays its seasonal variability.A new method is introduced in this paper to obtain the flux field via retrieval of ocean color remote sensing data,statistical analysis of historical suspended sediment concentration data,and numerical simulation of three-dimensional(3.) flow *** components of the sediment flux field include(i) surface suspended sediment concentration inverted from ocean color remote sensing data;(ii) vertical distribution of suspended sediment concentration obtained by statistical analysis of historical observation data;and(iii) 3. flow field modeled by a numerical *** the improved method,the 3. suspended sediment flux field in the YECS has been *** comparison with the suspended sediment flux field solely based on the numerical simulation of a suspended sediment transport model,the suspended sediment flux field obtained by the improved method is found to be more *** 3. suspended sediment flux field from ocean colour remote sensing and in situ observation are more closer to the ***,by quantitatively analyzing the newly obtained suspended sediment flux field,the quantity of sediment erosion and deposition within the different regions can be *** sediment exchange between the Yellow Sea and the East china Sea can be *** mechanism of suspended sediment transport in the YECS can be better *** particular,it is suggested that the long-term transport of suspended sediment is controlled mainly by the circulation pattern,especially the current in winter.

关键词： Suspended sediment flux field Seasonal variability Yellow and East china Seas Regression equation Numerical simulation

Two possible mechanisms for vortex self-organization

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china Earth sciences 2006年第2期49卷 202-211页

作者： LUO Zhexian2, ZHOU Xiuji1 & GAO Shouting3.1. chinese academy of Meteorological sciences, Beijing 100081,{3. 2. Department of Space Information Science, Nanjing University of Information Science and Technology, Nanjing 210044,{3. 3. institute of Atmospheric Physics, chinese academy of sciences, Beijing 100029,{3. Department of Environmental Science Nanjing University of Information Science and Technology Nanjing China chinese academy of Meteorological sciences Beijing China institute of Atmospheric Physics Chinese Academy of Sciences Beijing China

The vortex self-organization is investigated in this paper by four groups of numerical experiments within the framework of quasi-geostrophic model, and based on the experimental results two types of possible mechanisms for vortex self-organization are suggested. The meso-scale to-pography may enable separated vortices to merge into a larger scale vortex; and the interaction of meso-γ and meso-β scale systems may make separated vortices to self organize a typhoon-like vor-tex circulation.

关键词： vortex, self-organization, meso-scale topography, interaction of different scales.

Evaluation of Sustainable Land Management and Diagnosis of Obstacle at County Scale in Sichuan Basin:Taking Lezhi County as Example

在线全文

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural sciences 2006年第4期11卷 1046-1051页

作者： CHEN Guangjian 1, 2, 3., LIU Qing 1 1. Chengdu institute of Biology, chinese academy of sciences, Chengdu 610041, Sichuan,china 2. Graduate University of chinese academy of sciences, Beijing 100049, china 3. academy of Land Reconnaissance and Layout of Sichuan Province , Chengdu 61003., Sichuan, china Chengdu institute of Biology Chinese Academy of Sciences Chengdu Sichuan China Graduate University of chinese academy of sciences Beijing China academy of Land Reconnaissance and Layout of Sichuan Province Chengdu Sichuan China

This paper established sustainable land resources evaluating indicators fit for hilly area in Sichuan Basin, Southwest of china, and evaluated the case of sustainable land management of Lezhi County from 1990 to 2001. The result showed that the land resource sustainable utilization ability in Lezhi County is belong to Second level （better sustainable）. Secondly, this paper diagnosed some years obstacles of sustainable land management of Lezhi County from base period to goal period and compared the obstacles factors in the indicators system. There were 16 indexes orderly become major affect factor to land sustainable utilization of Lezhi county in indicator system, of which there are 8 obstacles indexes exist both in 1990 and 2001. The value of obstacles degree of five indicators exceeded 5 in 1990, but in 2001, only two indicators＇ values were more than 5.

关键词： land resources sustainable land management assessment indicators diagnosis of obstacle

Review on the study of entanglement in quantum computation speedup

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 2007年第16期52卷 2161-2166页

作者： DING ShengChao1,3.& JIN Zhi1,2,1 institute of Computing Technology,chinese academy of {3.,Beijing 100080,china 2 academy of Mathematics and Systems Science,chinese academy of {3.,Beijing 100080,china 3.Graduate University of chinese academy of sciences,Beijing 100080,china institute of Computing Technology Chinese Academy of Sciences Beijing China Graduate University of chinese academy of sciences Beijing China academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing China

The role the quantum entanglement plays in quantum computation speedup has been widely disputed. Some believe that quantum computation's speedup over classical computation is impossible if entan-glement is absent,while others claim that the presence of entanglement is not a necessary condition for some quantum algorithms. This paper discusses this problem systematically. Simulating quantum computation with classical resources is analyzed and entanglement in known algorithms is reviewed. It is concluded that the presence of entanglement is a necessary but not sufficient condition in the pure state or pseudo-pure state quantum computation speedup. The case with the mixed state remains open. Further work on quantum computation will benefit from the presented results.

关键词：量子论量子纠缠量子计算加速模拟

Sequence analysis of mRNA polyadenylation signals of rice genes

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 2006年第9期51卷 1069-1077页

作者： LU Ying1, 2, GAO Chenxi1,2,3.& HAN Bin1,3.41. National Center for Gene Research, Shanghai institutes for Biological sciences, chinese academy of sciences, Shanghai 20023.,{3. 2. Graduate School of the chinese academy of sciences, Beijing 10003.,{3. 3. institute of Plant Physiology and Ecology, Shanghai institutes for Biological sciences, chinese academy of sciences, Shanghai 20003.,{3. National Center for Gene Research Shanghai Institutes for Biological Sciences Chinese Academy of Sciences Shanghai China Graduate School of the chinese academy of sciences Beijing China institute of Plant Physiology and Ecology Shanghai Institutes for Biological Sciences Chinese Academy of Sciences Shanghai China

The formation of eukaryotic mRNAs involves the cleavage and polyadenylation of pre- mRNAs. To investigate the sequence requirement of putative polyadenylation signals (PASs), poly(A) sites and downstream elements (DUEs) in 3.-end-pro- cessing in rice, we compared expressed sequences tags (ESTs) with poly(A) extremity to full-length cDNA sequences and constructed a database of 12969 pre- mRNA sequences in ?40―+40 nt surrounding the poly(A) sites, which were from 9953.genes. The al- ternative poly(A) sites were revealed in approxi- mately 25% of mRNAs. Nearly 80% of pre-mRNAs showed stringent requirement of the YA (CA or UA) at poly (A) sites for polyadenylation. About 7.9% had the AAUAAA signals on ?40―?1 nt upstream of the poly(A) sites. Over 60% of mRNAs probably used the one- or two-base variants of AAUAAA hexamers as their PASs in 3. fragments. The single-base variants of AAUGAA revealed the high frequency in 11.5% of 3. fragments. The DUEs were detected in 90% of pre- mRNAs, especially more than half of the pre-mRNAs with multi-base variants of AAUAAA had the DUEs surrounding the poly(A) site. The location of DUE is also important for defining the cleavage site. Al- though most of the rice pre-mRNAs did not contain AAUAAA signal, the existence of downstream ele- ments ensured the efficiency of cleavage-polyade-

关键词：多聚腺苷酸序列分析 mRNA 水稻基因工程