检索结果-南通市图书馆

Principles and methods of quantitative analysis on b-axis disorder in 2.: 1 dioctahedral phyllosilicate

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 1997年第22期42卷 1908-1912页

作者： WANG Ling and ZHANG Zhenyu1. Changsha Institute of Geotectonics, chinese academy of sciences, Changsha 410013, china 2. Institute of Geology, chinese academy of sciences, beijing 10002., china Changsha Institute of Geotectonics Chinese Academy of Sciences Changsha China Institute of Geology Chinese Academy of Sciences Beijing China

IN XRD patterns of clay minerals, a phenomenon that strong peaks often have (00l) and(hkl) (k=3n) indices and show symmetric figures can be seen commonly, while a minorityof reflection peaks (hkl) (k≠3n) are comparat... 详细信息

关键词： b-axis disorder pyrophvllile 2 phyllosilicate clay minerals dioctahedral minerals orientating structure of hy-droxyls crystal structure analysis DTA-TG.

DNA barcoding:species delimitation in tree peonies

在线全文

学校读者我要写书评

暂无评论

Science china(Life sciences) 2009年第6期52卷 568-578页

作者： ZHANG JinMei1,2.WANG JianXiu1,2.XIA Tao1,2.& ZHOU ShiLiang1 1State Key Laboratory of Systematic and Evolutionary Botany,Institute of Botany,the chinese academy of sciences,beijing 100093,{2. 2.3} School of the chinese academy of sciences,beijing 100039,{2. 1. State Key Laboratory of Systematic and Evolutionary Botany Institute of Botany the Chinese Academy of Sciences Beijing 100093 China 2. graduate School of the chinese academy of sciences Beijing 100039 China

Delimitations of species are crucial for correct and precise identification of *** "spe-cies" is more a subjective than an objective concept in taxonomic practice due to difficulties in revealing patterns of infra-or inter-specific *** phylogenetic studies at the population level solve this problem and lay a sound foundation for DNA *** this paper we exemplify the necessity of adopting a phylogenetic concept of species in DNA barcoding for tree peonies(Paeonia ***).We used 40 samples representing all known populations of rare and endangered species and several populations of widely distributed tree *** currently recognized species and major variants have been included in this *** chloroplast gene fragments,***,rps16-trnQ,trnL-F and trnS-G(a total of 5040 characters,96 variable and 69 parsimony-informative characters) and one variable and single-copy nuclear GPAT gene fragment(2.93?2.97 bp,2.9 variable and 148 parsi-mony-informative characters) were used to construct phylogenetic relationships among the *** evolutionary lineages revealed by the nuclear gene and the chloroplast genes are inconsistent with the current circumscriptions of ***,***,***,and *** based on *** inconsistencies come from(1) significant chloroplast gene divergence but little nuclear GPAT gene divergence among population systems of *** + ***,and(2. well-diverged nuclear GPAT gene but little chloroplast gene divergence between *** and *** incongruence of the phylogenies based on the chloroplast genes and the nuclear GPAT gene is probably due to the chloro-plast capture event in evolutionary history,as no reproductive barriers exist to prevent inter-specific *** also evaluated the suitability of these genes for use as DNA barcodes for tree *** variability of chloroplast genes among well-defined species or population systems of a specie

关键词： DNA barcoding evolution Paeonia phylogeny species concept

Autonomous satellite constellation orbit determination using the star sensor and inter-satellite links data

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2010年第5期53卷 966-974页

作者： GAN QingBo1,2.MA JianBo1 & XU Jin1 1 Purple Mountain Observatory,chinese academy of sciences,Nanjing 2.0008,china {2. University of chinese academy of sciences,beijing 100049,china 1. Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China

A method of autonomous orbit determination for a satellite constellation using a star sensor combined with inter satellite links(ISLs) is *** types of simulated observation data,Three-Satellite Constellation ISLs and background stellar observations by a CCD star sensor,are first *** on these data,an observation equation is built for the constellation joint autonomous orbit determination,in which the simulations are *** accuracy of this method with different orbital determination models are analyzed and compared with regard to the effect of potential measurement *** results show that autonomous satellite constellation orbit determination using star sensor measurement and ISLs data is ***,this paper arrives at several conclusions which contribute to extending this method to a more general satellite constellation.

关键词： satellite constellation star sensor inter-satellite links autonomous orbit determination

Genesis of ^(2.0)Th excess in basalts from mid-ocean ridges and ocean islands:Constraints from the global U-series isotope database and major and rare earth element geochemistry

在线全文

学校读者我要写书评

暂无评论

Science china Earth sciences 2010年第10期53卷 1486-1494页

作者： ZHANG GuoLiang1,2.& ZENG ZhiGang1 1 Key Laboratory of Marine Geology and Environment,Institute of Oceanology,chinese academy of sciences,Qingdao 2.6071,china {2. University of chinese academy of sciences,beijing 100049,china 1. Key Laboratory of Marine Geology and Environment Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China

Based on 2.0Th-2.8U disequilibrium and major element data from mid-ocean ridge basalts(MORBs) and ocean island basalts(OIBs),this study calculates mantle melting parameters,and thereby investigates the origin of 2.0Th excess.(2.0Th/2.8U) in global MORBs shows a positive correlation with Fe8,Po,Na8,and Fmelt(Fe8 and Na8 are FeO and Na2. contents respectively after correction for crustal fractionation relative to MgO = 8 wt%,Po=pressure of initial melting and Fmelt=degree of melt),while 2.0Th excess in OIBs has no obvious correlation with either initial mantle melting depth or the average degree of mantle ***,compared with the MORBs,higher(2.0Th/2.8U) in OIBs actually corresponds to a lower melting *** suggests that the 2.0Th excess in MORBs is controlled by mantle melting conditions,while the 2.0Th excess in OIBs is more likely related to the deep garnet *** vast majority of calculated initial melting pressures of MORBs with excess 2.0Th are between 1.0 and 2.5 GPa,which is consistent with the conclusion from experiments in recent years that DU>DTh for Al-clinopyroxene at pressures of >1.0 *** initial melting pressure of OIBs is 2.2.3.5 GPa(around the spinel-garnet transition zone),with their low excess 2.6Ra compared to MORBs also suggesting a deeper mantle ***,excess 2.0Th in MORBs and OIBs may be formed respectively in the spinel and garnet stability *** addition,there is no obvious correlation of K2./TiO2.with(2.0Th/2.8U) and initial melting pressure(Po) of MORBs,so it is proposed that the melting depth producing excess 2.0Th does not tap the spinel-garnet transition *** and MORBs in both(2.0Th/2.8U) vs.K2./TiO2.and(2.0Th/2.8U) *** plots fall in two distinct areas,indicating that the mineral phases which dominate their excess 2.0Th are ***/Yb-Ce curves of fast and slow ridge MORBs are similar,while,in comparison,the Ce/Yb-Ce curve for OIBs shows more influence from *** mechanism

关键词： excess 2.0Th clinopyroxene garnet spinel-lherzolite mid-ocean ridge ocean island

Development of a Wire Driven Robot for Grinding with Stiffness Adapted

在线全文

学校读者我要写书评

暂无评论

厦门大学学报（自然科学版） 2002年第S1期41卷 81-82页

作者： ZHANG Bo 1,2. ZHAO Ming-yang 2.(1. graduate School of the chinese academy of sciences, {2. , china 2. Robotics Laboratory, Shenyang Institute of Automation, chinese academy of S ciences, Shenyang 110016, china)

Along with development of new design and machining me thod production with more complex surface can be manufactured. Researching on th e new equipment used for surface disposal has become the important matter. Grind ing and polishing are a common surface processing method. A new type wire driven parallel robot used for grinding processing is proposed in this paper. Wire driven parallel robot is developed from parallel robot and serial wire driven r obot. Steel wire is used to replace the leg of parallel robot. Compared with par allel robot, this kind of robot has lager workspace, lower weight, higher rigidi ty and higher load/deadweight ratio. And the stiffness of robot is controlled by changing the tension of wire. The robot proposed in this paper has three DOF. T he moving part is driven by four wires, three of them are used to drive and the rest to keep them tension, with a restraining machine. The position sensors are installed in restraining machine. The position of terminating of end-effecter c an be ascertained in the space. The tension sensors are installed in each wire t o form force feedback system. By changing the tension the force on the workpiece can be controlled. Also the stiffness of robot can be adjusted.

关键词： wire driven parallel robot stiffness control

Cytotoxicity of carbon nanotubes

在线全文

学校读者我要写书评

暂无评论

Science china Chemistry 2008年第11期51卷 1021-1029页

作者： ZHU Ying1,2.& LI WenXin1 1 Laboratory of Nano-biology and Medicine, Shanghai Institute of Applied Physics, chinese academy of sciences, Shanghai 2.1800, china {2. School of chinese academy of sciences, beijing 100049, china 1. Laboratory of Nano-biology and Medicine Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai 201800 China 2. graduate School of chinese academy of sciences Beijing 100049 China

With large-scale production and application at large scale, carbon nanotubes (CNTs) may cause ad-verse response to the environment and human health. Thus, study on bio-effects and safety of CNTs has attracted great attention from scientists and governments worldwide. This report briefly summa-rizes the main results from the in vitro toxicity study of CNTs. The emphasis is placed on the descrip-tion of a variety of factors affecting CNTs cytotoxicity, including species of CNTs, impurities contained, lengths of CNTs, aspect ratios, chemical modification, and assaying methods of cytotoxicity. However, experimental information obtained thus far on CNTs' cytotoxicity is lacking in comparability, and some-times there is controversy about it. In order to assess more accurately the potential risks of CNTs to human health, we suggest that care should be taken for issues such as chemical modification and quantitative characterization of CNTs in cytotoxicity assessment. More importantly, studies on physical and chemical mechanisms of CNTs' cytotoxicity should be strengthened; assaying methods and evaluating criteria characterized by nanotoxicology should be gradually established.

关键词： carbon nanotubes (CNTs) cell bio-security

Dynamic tree-based authenticated group key exchange protocol

在线全文

学校读者我要写书评

暂无评论

Science china(Information sciences) 2010年第8期53卷 1591-1602页

作者： LI Hui 1,2., WU ChuanKun 1 & TENG JiKai 1,2.1 State Key Laboratory of Information Security, Institute of Software, chinese academy of sciences, beijing 100190, {2. 2.graduate University of chinese academy of sciences, beijing 100049, {2. 1. State Key Laboratory of Information Security Institute of Software Chinese Academy of Sciences Beijing 100190 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China

Authenticated group key exchange protocols allow a group of users over a public network to establish a shared secret key for the subsequent cryptographic goals. In this paper, we extend BD-II scheme into a dynamic setting, and propose a tree-based authenticated key exchange protocol which is more suitable for dynamic groups in such as ad hoc networks. Our protocol is proven secure in random-oracle model. Additionally, we analyze the costs of our protocols in both communication and computation terms, and compare its performance with three well-known protocols.

关键词： tree-based group key exchange dynamic provable security

Mechanism and Defense on Malicious Code

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural sciences 2005年第1期10卷 83-88页

作者： WEN Wei-ping 1,2.3, QING Si-han 1,2.31. Institute of Software, the chinese academy of sciences, beijing 100080, {2. 2.Engineering Research Center for Information Security Technology, the chinese academy of sciences, beijing 100080, {2. 3.graduate School of the chinese academy of sciences, beijing 100080, {2. Institute of Software the Chinese Academy of Sciences Beijing 100080 China

With the explosive growth of network applications, the threat of the malicious code against network security becomes increasingly serious. In this paper we explore the mechanism of the malicious code by giving an attack model of the malicious code, and discuss the critical techniques of implementation and prevention against the malicious code. The remaining problems and emerging trends in this area are also addressed in the paper.

关键词： malicious code attacking model mechanism defense system security network security

Genetic fingerprinting of plankton community provides new insights into aquatic ecology

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2006年第9期16卷 893-898页

作者： YAN Qingyun, YU Yuhe and FENG Weisong ( Institute of Hydrobiology, chinese academy of sciences, Wuhan 430072. china {2. School of the chinese academy of Sci-ences, beijing 100039, china) [a]Institute of Hydrobiology Chinese Academy of Sciences Wuhan China [b]graduate School of the chinese academy of sciences Bejing China

Over the past two decades, molecular techniques have been widely used in ecological study and molecular ecology has been one of the most important branches of ecology. Meanwhile, genetic fingerprinting analyses have significantly enhanced our knowledge of the diversity and evolutionary relations of the planktonic organisms. Compared with conventional approaches in ecological study (e.g. morphological classification), genetic fingerprinting techniques are simpler and much more effective. This review provides an overview of the principles, advantages and limitations of the commonly used DNA fingerprinting techniques in plankton research. The aim of this overview is to assess where we have been, where we are now and what the future holds for solving aquatic ecological problems with molecular-level information.

关键词： genetic fingerprinting plankton community aquatic ecology genetic diversity.