检索结果-南通市图书馆

Preparation of well-defined polystyrene/silica hybrid nanoparticles by ATRP

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 Chemistry 2008年第1期51卷 51-57页

作者： OU BaoLi1,2.LI DuXin2.1 college of Chemistry and Chemical Engineering,Hunan University of science and {2.,Xiangtan 4112.1, china 2.State Key Laboratory of Powder Metallurgy,Central South University,Changsha 410083, china 1. college of Chemistry and Chemical Engineering Hunan University of Science and Technology Xiangtan 411201 China 2. State Key Laboratory of Powder Metallurgy Central South University Changsha 410083 China

Immobilization of the atom transfer radical polymerization (ATRP) macroinitiators at the silica nanoparticle surfaces was achieved through surface modification with excess toluene-2.4-diisocynate (TDI), after which the residual isocyanate groups were converted into ATRP macroinitiators. Structurally well-defined polystyrene chains were grown from the nanoparticle surfaces to yield individual particles composed of a silica core and a well-defined, densely grafted outer polystyrene by ATRP, which was initiated by the as-synthesized silica-based macroinitiator. FTIR, NMR and gel permeation chro-matography (GPC) were used to characterize the polystyrene/silica hybrid particles.

关键词： silica nanoparticles surface modification atom transfer radical polymerization polystyrene hybrid particle

Statistical theory for hydrogen bonding fluid system of A_aD_d type (I): The geometrical phase transition

在线全文

学校读者我要写书评

暂无评论

science china Chemistry 2006年第6期49卷 499-506页

作者： WANG Haijun1,2. HONG Xiaozhong3, GU Fang1 & BA Xinwu1 1. college of Chemistry and Environment science, Hebei University, Baoding 071002. {2. 2. International Center for Materials Physics, Chinese Academy of sciences, Shenyang 110016, {2. 3. college of Physics science and technology, Hebei University, Baoding 071002. {2. 1. college of Chemistry and Environment science Hebei University Baoding 071002 China 2. International Center for Materials Physics Chinese Academy of Sciences Shenyang 110016 China 3. college of Physics science and {2. Hebei University Baoding 071002 China

The influence of hydrogen bonds on the physical and chemical properties of hydrogen bonding fluid system of AaDd type is investigated from two viewpoints by the principle of statistical mechanics. In detail, we proposed two new ways that can be used to obtain the equilibrium size distribution of the hydrogen bonding clusters, and derived the analytical expression of a relationship between the hydrogen bonding free energy and hydrogen bonding degree. For the nonlinear hydrogen bonding systems, it is shown that the sol-gel phase transition can take place under proper conditions, which is further proven to be a kind of geometrical phase transition rather than a thermodynamic one. Moreover, several problems associated with the geometrical phase transition and liquid-solid phase transition in nonlinear hydrogen bonding systems are discussed.

关键词： hydrogen bonding fluid, equilibrium free energy, geometrical phase transition.

Improved AHP Method and Its Application in the Evaluation of Agricultural Mechanization

在线全文

学校读者我要写书评

暂无评论

Journal of Systems science and Systems Engineering 2001年第4期13卷 403-408页

作者： HE Yong1 , GE Xiao-feng1 , CHEN Li-neng2., CHEN Su-shan2.1. college of Agricultural Engineering & Food science, {2. University, hangzhou 3l002., china 2. Jinhua college of science and technology, Jinhua 32.017, china college of Agricultural Engineering & Food science Zhejiang UniversityHangzhou 310029 China Jinhua college of science and {2. Jinhua 321017 China

On the basis of analyzing the shortage of scale measure of the current AHP, and following base principIe of two comparison: principle of reward-punishment and principle of conversion, translation function and conciliation coefficient have been structured. This article advances a new measure which structuring translation function and conciliation coefficient. The result of application of improved AHP on the synthesis evaluation of agricultural mechanization is satisfactory.

关键词： improved AHP: agricultura1 mechanization1 evaluation

Monte Carlo calculation method on low energy electronscattering in polybasic medium

在线全文

学校读者我要写书评

暂无评论

Chinese science Bulletin 1998年第2期43卷 171-174页

作者： TAN Zhenyu 1 and HE Yancai 2.1. college of Electric Power, Shandong University of technology, Jinan 2.0061, {2. 2. Shanghai Institute of Ceramics, Chinese Academy of sciences, Shanghai 2.0050, {2. college of Electric Power Shandong University of Technology Jinan China Shanghai Institute of Ceramics Chinese Academy of Sciences Shanghai China

A novel Monte Carlo method of simulating low energy electron (LEE) scattering in polybasic medium is presented. The Mott cross section is adopted to describe the elastic scattering of LEE, and a mean cross section idea is proposed instead of usual determination of the scattering center. The Joy’’s modified Bethe equation is used to calculate energy loss of LEE. The scattering processes of LEE in bulk PMMA have been simulated. And the electron backscattering coefficients, the electron interaction range and energy dissipation distribution of LEE in bulk PMMA have been calculated and compared with those calculated by the method of determining scattering center.

关键词： low_energy electron scattering Monte Carlo method cross_section.

Preparation of polystyrene/silica nanocomposites by radical copolymerization of styrene with silica macromonomer

在线全文

学校读者我要写书评

暂无评论

science china Chemistry 2007年第3期50卷 385-391页

作者： OU BaoLi1,2.& LI DuXin2.1 college of Chemistry and Chemical Engineering, Hunan University of science and {2., Xiangtan 4112.1, china 2.State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, china 1. college of Chemistry and Chemical Engineering Hunan University of Science and Technology Xiangtan 411201 China 2. State Key Laboratory of Powder Metallurgy Central South University Changsha 410083 China

A two-stage process has been developed to generate the silica-based macromonomer through surface-modification of silica with polymerizable vinyl groups. The silica surfaces were treated with excess 2.4-toluene diisocynate (TDI), after which the residual isocyanate groups were converted into polymerizable vinyl groups by reaction with hydroxypropylacrylate (HPA). Thus, polystyrene/silica nanocomposites were prepared by conventional radical copolymerization of styrene with silica macromonomer. The main effecting factors, such as ratios of styrene to the macromonomer, together with polymerization time on the copolymerization were studied in detail. FTIR, DSC and TGA were utilized to characterize the nanocomposites. Experimental results revealed that the silica nanoparticles act as cross-linking points in the polystytene/silica nanocomposites, and the glass transition temperatures of the nanocomposites are higher than that of the corresponding pure polystyrene. The glass transition temperatures of nanocomposites increased with the increasing of silica contents, which were further ascertained by DSC.

关键词： silica nanoparticles surface modification styrene radical copolymerization nanocomposites

Role of ethylene signaling in the production of rice volatiles induced by the rice brown planthopper Nilaparvata lugens

在线全文

学校读者我要写书评

暂无评论

science Bulletin 2006年第20期51卷 2457-2465页

作者： LU Yujie1,2. WANG Xia1, LOU Yonggen1 & CHENG Jiaan1 1. Institute of Insect sciences, zhejiang University, {2. 31002., china 2. college of Food and Oil, Henan University of technology, Zhengzhou 450052. china Institute of Insect sciences Zhejiang University Hangzhou 310029 China college of Food and Oil Henan University of Technology Zhengzhou 450052 China

Ethylene signaling pathway plays an important role in induced plant direct defense against herbivores and pathogens; however, up to now, only few researches have focused on its role in induced plant indirect defense, i.e. the release of herbi- vore-induced volatiles, and the results are variable. Using a model system consisting of rice plants, the rice brown planthopper Nilaparvata lugens and its egg parasitoid Anagrus nilaparvatae, we examined the role of ethylene signaling in the production of rice volatiles induced by N. lugens by measuring both the timing of herbivore-induced ethylene levels and the relationships between ethylene, rice volatiles and attraction of the parasitoid. N. lugens infestation sig- nificantly enhanced the release of ethylene during 2.2. h after infestation. Plants treated with eth- ephon, a compound that breaks down to release ethylene at cytoplasmic pH, released volatiles profiles similar to those released by N. lugens-infested plants, and both of them showed an equal attraction of the parasitoid. Moreover, pretreatment with 1-MCP, an inhibitor of ethylene perception, reduced the release of most of rice volatiles whose amount was enhanced by N. lugens infestation and decreased the attrac- tiveness to the parasitoid. These results demonstrate that ethylene signaling is required for the production of rice volatiles induced by N. lugens.

关键词： ethylene signaling pathway Nilaparvata lugens Anagrus nilaparvatae herbivore-induced rice volatiles rice tritrophic inter- action.

Using multi-matching system based on a simplified deformable model of the human iris for iris recognition

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 Bionic Engineering 2004年第3期1卷 183-190页

作者： MING Xing , XU Tao , WANG Zheng-xuan 1 2.3 1. college of computer {2. and technology, Nanling Campus,Jilin University, 5988 Renmin Street,Changchun 13002., P. R. china 2. college of Mechanical {2. and Engineering, Nanling Campus,Jilin University, 5988 Renmin Street, Changchun 13002., P. R. china 3. college of computer {2. and technology, Qianwei Campus,Jilin University, 10 Qianwei Road, Changchun 130012. P. R. china. Jilin University Jilin University Jilin University

A new method for iris recognition using a multi-matching system based on a simplified deformable model of the human iris was proposed. The method defined iris feature points and formed the feature space based on a wavelet transform. In the matching stage it worked in a crude manner. Driven by a simplified deformable iris model, the crude matching was refined. By means of such multi-matching system, the task of iris recognition was accomplished. This process can preserve the elastic deformation between an input iris image and a template and improve precision for iris recognition. The experimental results indicate the va- lidity of this method.

关键词： iris recognition wavelet transform feature points deformable model

Complex variable method for plane elasticity of icosahedral quasicrystals and elliptic notch problem

在线全文

学校读者我要写书评

暂无评论

science china(Physics,Mechanics & Astronomy) 2008年第7期51卷 773-780页

作者： LI LianHe1,2.& FAN TianYou1 1 Department of Physics, Beijing Institute of technology, Beijing 100081, china {2. of Mathematics science, Inner Mongolia Normal University, Hohhot 01002., china Department of Physics Beijing Institute of Technology Beijing 100081 China college of Mathematics science Inner Mongolia Normal University Hohhot 010022 China

The complex variable method for the plane elasticity theory of icosahedral quasicrystals is developed. Based on the general solution obtained previously, complex representations of stress and displacement components of phonon and phason fields in the quasicrystals are given. With the help of conformal transformation, an analytic solution for the elliptic notch problem of the material is presented. The solution of the Griffith crack problem can be observed as a special case of the results. The stress intensity factor and energy release rate of the crack are also obtained.

关键词： icosahedral quasicrystals plane elasticity elliptic notch complex variable method

Sufficient and necessary conditions for Lyapunov stability of Lorenz system and their application

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 1574-1583页

作者： LUO Qi 1 , LIAO XiaoXin 2.& ZENG ZhiGang 2.1 college of Information and Control, Nanjing University of Information science and {2., Nanjing 2.0044, china 2.Department of Control science and Engineering, Huazhong University of science and {2., Image Processing and Intelligent Control Key Laboratory of Education Ministry of china, Wuhan 430074, china 1. college of Information and Control Nanjing University of Information Science and Technology Nanjing 210044 China2. Department of Control Science and Engineering Huazhong University of Science and Technology Image Processing and Intelligent Control Key Laboratory of Education Ministry of China Wuhan 430074 China

The sufficient and necessary conditions for Lyapunov stability of the zero equilibrium point of Lorenz system are discussed, and some brief criteria are presented for globally exponential stability, globally asymptotical stability and instability. Furthermore, the behavior of the non-zero equilibrium point of Lorenz system is also investigated, and several sufficient and necessary conditions are provided for locally exponential stability and instability. The established theorems in this paper develop and extend the existing achievements on Lyapunov stability of Lorenz system. In conclusion, by applying the obtained results, some less conservative feedback-control laws are derived to guarantee the globally exponential stability of the chaos control of Chen system, Lu¨ system, Yang-Chen system and Yu-Xia Li system.

关键词： Lorenz system Lyapunov stability sufficient and necessary condition bifurcation values globally exponential synchronization