检索结果-南通市图书馆

Science china Chemistry 2005年第2期48卷 107-114页

作者： ZHANG Zejiang1,2,3, MEI Xiujuan2, XU Chenghua1 & QIU Fali1 1. Chengdu Institute of Organic Chemistry, chinese academy of sciences, Chengdu 610041, china 2. Sichuan Fire Research Institute of Public security Ministry, Chengdu 611830, china 3. graduate school of the chinese academy of sciences, beijing 100039, china Correspondence should be addressed to Zhang Zejiang (email: zzjzzjzz@***) 1. Chengdu Institute of Organic Chemistry Chinese Academy of Sciences 610041 Chengdu China 2. Sichuan Fire Research Institute of Public security Ministry 611830 Chengdu China 3. graduate school of the chinese academy of sciences 100039 Beijing China

The coating process of a nano-scale SiO2 film on the nanocrystalline Mg-Al layered double hydroxides via a sol-gel process was investigated. The uniform and dense SiO2film with a thickness of about 5 nm on the nano-LDHs particles was characterized by the solubility test in the dilute HNO3 or HCl acid, TEM and FT-IR, XRD, TG and DSC. The chemical shifts of binding en- ergies of Al 2p, Mg 2p, Si 2s and O 1s on the coated particles indicate that the coating of the SiO2 nano-film on the surface of the nano-LDHs proceeds through the formation of Mg-O-Si and Al-O-Si bonds. The thermal analysis shows that both the SiO2-coated nano-LDHs and the nano-LDHs have a similar mass loss process, in which there are three obvious stages of mass loss in the temperature range of 40—700℃. Furthermore, the more the coatedamount of SiO2on the surface of the nano-LDHs is, the less the mass loss of the samples is at 700℃.The nano- LDHs have two obvious endothermic peaks at 244.67℃ and 430.13℃, whose corresponding heat absorption capacities are 412.28 J/g and 336.30 J/g, respectively. In contrast, the coated nano-LDHs have only one endothermic peak at 243.60℃ with a heat absorption capacity of 221.25 J/g.

关键词： layered double hydroxides, nanocrystalline, silica, coating.

在线全文

学校读者我要写书评

暂无评论

人神经tau蛋白与DNA相互作用

生物化学与生物物理进展 2004年第10期31卷 918-923页

作者：曲梅花李辉徐艳娟赫荣乔中国科学院生物物理研究所中国科学院物理研究所

通过凝胶阻滞实验表明 ,人类神经tau能够与不同来源的DNA (λDNA ,质粒DNA以及PCR产物 )相结合 ,形成tau DNA复合物 .每分子神经tau大约与长度为 6～ 10bp的核苷酸片段结合 .原子力显微镜直接证实了tau与线性质粒DNA相结合形成串珠样的... 详细信息

通过凝胶阻滞实验表明 ,人类神经tau能够与不同来源的DNA (λDNA ,质粒DNA以及PCR产物 )相结合 ,形成tau DNA复合物 .每分子神经tau大约与长度为 6～ 10bp的核苷酸片段结合 .原子力显微镜直接证实了tau与线性质粒DNA相结合形成串珠样的结构 .采用单克隆抗体Tau 1,进行免疫组织化学的实验显示 ,神经tau不但弥散地分布在SY5Y细胞系的细胞质内 ,同时也存在于细胞核中 ,并形成染色致密的斑点 .以上结果提示 :神经tau在细胞核中可能参与了某种重要的生物学功能 .

关键词：人神经tau DNA 相互作用原子力显微镜(AFM)

Spatial Distribution of Land Cover and Vegetation Activity along Topographic Gradient in an Arid River Valley, SW china

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2009年第3期6卷 274-285页

作者： LIU Wen XU Xianli LUO Jiancheng SHEN Zhanfeng ZHONG Qiuhai Department of Automatic Control School of Automation Beijing Institute of Technology Beijing 100081 China state key laboratory of Urban and Regional Ecology Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China Institute of Remote Sensing Applications Chinese Academy of Sciences Beijing 100101 China Centre for Hydrology Micrometeorology and Climate Change Department of Civil and Environmental Engineering University College Cork Cork Ireland

Anthropogenic activities have become more and more important in characterizing the landscape, but their impacts are still restricted by natural environments. This paper discusses the interactions of anthropogenic activity, vegetation activity and topography through describing the spatial distribution of land cover and vegetation activity (represented by Normalized Difference Vegetation Index, NDVI) along topographic gradient in a mountainous area of southwestern china. Our results indicate that the existing landscape pattern is controlled by anthropogenic activities as well as topographic factors. Intensive anthropogenic activities mainly occur in areas with relatively low elevation, gentle and concave slopes, as these areas are easy and convenient to attain for human. Because of the destruction by human, some land cover types (mainly grassland and shrub) are only found in relatively harsher environments. This study also finds that topographic wetness index (W) used in other places only reflects runoff generation capacity, but not indicate the real spatial pattern of soil water content in this area. The relationships between NDVI and W, and NDVI and length slope factor (LSF) show that runoff and erosion have complex effects on vegetation activity. Greater values of W and LSF will lead to stronger capacity to produce runoff and transport sediment, and thereby increase soil water content and soil deposition, whereas beyond a certain threshold runoff and erosion are so strong that they would destruct vegetation growth. This study provides information needed to successfully restore native vegetation, improve land management, and promote sustainable development in mountainous areas, especially for developing regions.

关键词： Vertical distribution of land cover Anthropogenic activity Vegetation activity Environmental variability china

The Research and Development of Worm Defense Strategies

在线全文

学校读者我要写书评

暂无评论

The Research and Development of Worm Defense Strategies

Efficient DPCA SAR imaging with fast iterative spectrum reconstruction method

2010 3rd IEEE International Conference on Computer Science and information Technology—ICCSIT 2010

作者： Liuqi 1 1 state key laboratory of information security graduate University of chinese academy of Science beijing china Ma Guoqing 2 2 National key laboratory of Science and Technology on information System security beijing china

The deterioration of worm propagation on internet in recent years has pushed the research in the field of worm defense, as a result there are coming up plenty of worm defense strategies. This paper refers to make the systematic study of the complete worm defense strategies and provide taxonomy of worm defense system strategies according to the key factors of each defense category. As guideline for the design of worm defense, we compare the present evaluation of the worm defense strategies, and give a highlight on the trendy of worm defense in the future at the end.

关键词： worm defense evaluation math modeling simulation

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Science china(information sciences) 2012年第8期55卷 1838-1851页

作者： FANG Jian1,ZENG JinShan1,XU ZongBen1&ZHAO Yao2 1M inistry of Education key Lab for Intelligent Networks and Network security Xi'an Jiaotong University,Xi'an 710049,china 2N ational key laboratory of Science and Technology on Microwave Imaging&Institute of Electronics,chinese academy of sciences,beijing 100049,china 1. Ministry of Education key Lab for Intelligent Networks and Network security Xi’an Jiaotong University Xi’an 710049 China2. National Key Laboratory of Science and Technology on Microwave Imaging & Institute of Electronics Chinese Academy of Sciences Beijing 100049 China

The displaced phase center antenna(DPCA)technique is an effective strategy to achieve wide-swath synthetic aperture radar(SAR)imaging with high azimuth ***,traditionally,it requires strict limitation of the pulse repetition frequency(PRF)to avoid non-uniform ***,any deviation could bring serious ambiguity if the data are directly processed using a matched *** break this limitation,a recently proposed spectrum reconstruction method is capable of recovering the true spectrum from the nonuniform ***,the performance is sensitive to the selection of the *** regularization based imaging may provide a way to overcome this *** existing time-domain method,however,requires a large-scale observation matrix to be built,which brings a high computational *** this paper,we propose a frequency domain method,called the iterative spectrum reconstruction method,through integration of the sparse regularization technique with spectrum analysis of the DPCA *** approximately expressing the observation in the frequency domain,which is realized via a series of decoupled linear operations,the method performs SAR imaging which is then not directly based on the observation matrix,which reduces the computational cost from O(N2)to O(N log N)(where N is the number of range cells),and is therefore more efficient than the time domain *** sparse regularization scheme,realized via a fast thresholding iteration,has been adopted in this method,which brings the robustness of the imaging process to the PRF *** provide a series of simulations and ground based experiments to demonstrate the high efficiency and robustness of the *** simulations show that the new method is almost as fast as the traditional mono-channel algorithm,and works well almost independently of the PRF ***,the suggested method can be accepted as a practical and efficient wide-swath SAR imaging technique.

关键词： displaced phase center antenna sparse regularization iterative thresholding spectrum reconstruction

CONSENSUS CONTROL FOR LEADER-FOLLOWING MULTI-AGENT SYSTEMS WITH MEASUREMENT NOISES

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2010年第1期23卷 35-49页

作者： Cuiqin MA Tao LI Jifeng ZHANG school of Mathematical sciences Qufu Normal University Qufu 273165 China. key laboratory of Systems and Control Institute of Systems Science Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China.

This work is concerned with consensus control for a class of leader-following multi-agentsystems (MASs).The information that each agent received is corrupted by measurement *** the impact of noises on consensus,time-varying consensus gains are adopted,based on whichconsensus protocols are *** using the tools of stochastic analysis and algebraic graph theory,asufficient condition is obtained for the protocol to ensure strong mean square consensus under the *** condition is shown to be necessary and sufficient in the noise-free ***,by using a common Lyapunov function,the result is extended to the switching topology case.

关键词： Consensus protocol leader-following multi-agent system stochastic noise.

Design theory and method of multivariate hash function

在线全文

学校读者我要写书评

暂无评论

Science china(information sciences) 2010年第10期53卷 1977-1987页

作者： WANG HouZhen 1,2 , ZHANG HuanGuo 1 , WU QianHong 1 , ZHANG Yu 1 , LI ChunLei 1 & ZHANG XinYu 1 1 The key laboratory of Aerospace information security and Trusted Computing, Ministry of Education, school of Computer, Wuhan University, Wuhan 430072, china 2 key laboratory of Mathematics Mechanization, beijing 100080, china 1. The key laboratory of Aerospace information security and Trusted Computing Ministry of Education School of Computer Wuhan University Wuhan 430072 China2. Key Laboratory of Mathematics Mechanization Beijing 100080 China

This paper proposes a novel hash algorithm whose security is based on the multivariate nonlinear polynomial equations of NP-hard problem over a finite field and combines with HAIFA iterative framework. Over the current widely used hash algorithms, the new algorithm has the following advantages: its security is based on a recognized difficult mathematical problem; the hash length can be changed freely; its design can be automated such that users may construct specific hash function meeting the actual needs. Furthermore, we discuss the security, efficiency and performance of the new algorithm. Under some related difficult mathematical assumptions and theoretical analysis, the new algorithm is proven practical by the experiment results, and capable of achieving security of an ideal hash function by choosing suitable parameters. In addition, it can also be used as a pseudo-random number generator for the good randomness of its output.

关键词： cryptology hash function MQ problem multivariate polynomials

A new perturbation algorithm and enhancing security of SFLASH signature scheme

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(information sciences) 2010年第4期53卷 760-768页

作者： WANG HouZhen1,2, ZHANG HuanGuo1,2*, GUAN HaiMing3 & HAN HaiQing1,2 1The key laboratory of Aerospace information security and Trusted Computing, Ministry of Education, Wuhan University, Wuhan 430072, china 2school of Computer, Wuhan University, Wuhan 430079, china 3chinese Electronic Equipment System Corporation, beijing 100039, china 1. The key laboratory of Aerospace information security and Trusted Computing Ministry of Education Wuhan University Wuhan 430072 China2. School of Computer Wuhan University Wuhan 430079 China3. Chinese Electronic Equipment System Corporation Beijing 100039 China

This paper introduces the concept of noise factor and noise operation, and constructs a noise group. We present a new perturbation algorithm for enhancing security of multivariate public key cryptosystems (MPKCs). European Consortium SFLASH which derives from Matsumoto-Imai scheme is a fast signature scheme intended for low cost smart cards. It was broken with the differential cryptanalysis by Dubois et al. in 2007. Taking Matsumoto-Imai system as an example, security analysis shows that the new algorithm can powerfully demolish its potential mathematical properties of the public key, and effectively avoid differential cryptanalysis without lowering the effciency of the original algorithm.

关键词： SFLASH differential cryptanalysis noise factor noise operation noise group

The Study and Perspective of Mobile Agent security

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

The Journal of china Universities of Posts and Telecommunications 2004年第4期11卷 48-53页

作者： MU Honga~1 WANG Ru-chuan~(1,2) WANG Hai-yan~11.Department of Computer Science and Technology,Nanjing University of Posts and Telecommunications,Nanjing 210003,P.R.china 2.state key laboratory of information security(graduate school of chinese Aeademy of sciences),beijing 100039,P.R.china Department of Computer Science and Technology Nanjing University of Posts and Telecommunications Nanjing 210003

security is an important issue for the widespread deployment of applications based on software agent *** is generally agreed that without the proper countermeasures in place,use of agent-based applications will be *** many projects have focused on the security issues of mobile agent and many mechanisms have been proposed tosolve the security *** paper discusses the security issues and the *** it points out some direc-tions for the research of the mobile agent security.

关键词： mobile agent mobile code security cryptography