检索结果-南通市图书馆

Science China chemistry 2010年第3期53卷 618-624页

作者： LIU JiangTao1,LIU ShaoPu2 & LIU ZhongFang2 1School of chemistry,Chongqing Normal university,Chongqing 400300,China 2School of chemistry and Chemical Engineering,Southwest university,Chongqing 400715,China School of chemistry Chongqing Normal University Chongqing China School of chemistry and Chemical Engineering Southwest University Chongqing China

The forming of bleomycinA2-Cu(Ⅱ) cationic chelate and the interaction of the chelate with DNA have been investigated by using resonance Rayleigh scattering(RRS),molecular absorption and fluorescence *** result shows that in aqueous solution,bleomycinA2(BLMA2) can react with Cu(Ⅱ) to form 1:1 cationic chelate which contributes to the changes of the absorption spectra and the quenched fluorescence of *** the cationic chelate further bound with DNA to form ternary ion-association complexes,the remarkable enhancement of the RRS intensity was *** this work,the optimum conditions for the coordination reaction of BLMA2 with Cu(Ⅱ) and some influencing factors have been *** reaction mechanism of BLMA2-Cu(Ⅱ) binding with DNA was suggested and a binding model was *** addition,the fluorescence quenching type of BLMA2 was investigated.A highly sensitive,simple and rapid new method for the determination of DNA by using BLMA2-Cu(Ⅱ) as RRS probe has been *** detection limits(3σ) are 7.2 ng/mL for ctDNA,7.1 ng/mL for sDNA and 18 ng/mL for *** method can be applied to the determination of trace amounts of DNA.

关键词： bleomycinA2 Cu(Ⅱ) DNA resonance Rayleigh scattering fluorescence quenching

Theoretical study on the hydrolysis mechanism of N,N-dimethyl-N′-(2′,3′-dideoxy-3′-thiacytidine)formamidine

在线全文

学校读者我要写书评

暂无评论

Science China chemistry 2008年第10期51卷 911-917页

作者： ZHANG Chang1 & XUE Ying2? 1 College of chemistry and Environment Protection Engineering, Southwest university for Nationalities, Chengdu 610041, China 2 College of chemistry, Sichuan university, Chengdu 610064, China 1. College of chemistry and Environment Protection Engineering Southwest University for Nationalities Chengdu 610041 China 2. College of chemistry Sichuan University Chengdu 610064 China

The hydrolysis mechanisms of N,N-dimethyl-N′-(2′,3′-dideoxy-3′-thiacytidine)formamidine (FA-3TC) in the gas phase and in aqueous solution were studied by use of the density functional theory B3LYP/6-31+G(d, p) method. Two possible reaction pathways in the title reaction were considered. In one pathway water attacks the C=N double bond first (path A) while in the other water attacks the C—N single bond first (path B). The calculated results indicate that the first step in both pathways is the rate-limiting process and path A is more favorable than path B in the gas phase. The effect of solvent water on the title reaction was assessed at the B3LYP/6-31+G(d, p) level of theory based on the po-larizable continuum model (CPCM). In water the first mechanism (path A) is also favored.

关键词： N N-dimethyl-N′-(2′ 3′-dideoxy-3′-thiacytidine)formamidine hydrolysis solvent effect B3LYP polarizable continuum model

Adsorption and corrosion inhibition behavior of imidazole on cobalt electrodes studied by SERS and electrochemical methods

在线全文

学校读者我要写书评

暂无评论

Science China chemistry 2005年第6期48卷 497-503页

作者： GU Wei1, LIU Guokun2, REN Bin2, WU Deyin2, GU Renao1 & TIAN Zhongqun2 1. Department of chemistry, College of chemistry and Chemical Engineering, Suzhou university, Suzhou 215006, China 2. State Key Laboratory for Physical chemistry of Solid Surfaces and Department of chemistry, College of chemistry and Chemical Engineering, Xiamen university, Xiamen 361005, China 1. Department of chemistry College of Chemistry and Chemical Engineering Suzhou University 215006 Suzhou China 2. State Key Laboratory for Physical chemistry of Solid Surfaces and Department of chemistry College of Chemistry and Chemical Engineering Xiamen University 361005 Xiamen China

The interaction of imidazole with Co electrodes in an electrochemical system was studied by surface-enhanced Raman scattering (SERS) and electrochemical methods. The SER spectra of Co in an imidazole solution as a function of the applied potential were analyzed and the assignment of the Raman bands was made. It was found that there were three kinds of sur-face species on the Co surface in different potential regions and they were interchangeable de-pending on the potential. In a relatively negative potential region (?1.2 to ?0.9 V), imidazole was adsorbed on the surface and its orientation might change from a vertical configuration via the N-end of the pyridine ring to a tilted configuration via the C2=N3 double bond. In a more positive potential region (?0.8 to ?0.7 V), the SERS signal from the adsorbed imidazole weakened and finally disappeared, meanwhile the signal from the Co and imidazole complex strengthened gradually. At the open circuit potential (?0.6 V), we detected very strong bands from the Co ox-ides. By comparing the Tafel curves of the Co electrode in the solution without and with imidazole, we found that imidazole has a marked effect on the corrosion inhibition of the Co electrode. This result demonstrates that we may be able to reveal the complicated interaction of surface species with metal surface at the molecular level by combining the SERS and electrochemical methods.

关键词： cobalt, imidazole, inhibition, surface-enhanced Raman spectroscopy, Tafel plot.

REGIME MORPHOLOGY OF EQUILIBRIUM ALLUVIAL CHANNELS

在线全文

学校读者我要写书评

暂无评论

International Journal of Sediment Research 1999年第2期14卷 187-194页

作者： Panayiotis DIPLAS1 (Dept.of Civil Engineering virginia Polytechnic Institute and State university, Blacksburg VA,24061, usa)

The concept of turbulent diffusion of downstream momentum in the lateral direction is employed here to develop a model for obtaining the shear stress applied by the flow upon the boundary of channels. The resulting equation, together with the equation desrcibing the balances of forces applied on a sediment particle lying on the channel boundary, are solved numerically to calculate the dimensions of equilibrium alluvial channels. More specifically, threshold channels, and channels with static banks and mobile beds are considered here. Such channels are widely used for irrigation, water supply, flood control and other purposes. The center depth and top channel width obtained from the present model compare favorably with the corresponding values measured from natural streams and laboratory flumes that have reached an equilibrium state.

关键词： Equilibrium alluvial channel Regime morphology shear stress Numerical model

Studies on the Morphology of Natural Rubber/Polyacrylate Interpenetrating Polymer Networks

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 1990年第1期6卷 85-89页

作者： Llao Kalrong (Institute of Polymer Science, Zhangshan university, Guangzhou)Thomas C. Ward (Department of chemistry, virginia Polytechnic Institute and State university, Blacksburg, VA, usa)

The interpenetrating polymer network(IPN) systems have attracted a lot of attention because of their unique two-phase structure and properties. There have been many publications concerning the IPNs in which poly (isoprene) (PIP) or polyacrylates (PAC) is formed as one of the *** the present study, Four serles of natural rubber(NR)/PAC IPNs were prepared and their morphologies were investigated with dynamic mechanics analysis(DMA) and transmission electron microscopy (TEM).

关键词： Interpenetrating polymer network Natural rubber Polyacrylate

Microstructures and Mechanical Properties of Ceramic/Metal Gradient Thermal Barrier Coatings

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan university of Technology(Materials Science) 2003年第4期18卷 38-40页

作者：肖金生 JIANGBing LIUJie HUANGShi-yong WuhanuniversityofTechnology virginiaPolytechniclnstituteandStateuniversity（usa）

The ceramic/metal gradient thermal barrier coatings (CMGTBCs) which combined the conceptions of thermal barrier coatings (TBCs) and functional gradient materials (FGMs) are *** structure model studied in this paper is a general model which includes four different layers:pure ceramic layer,ceramic/metal gradient layer,pure metal layer,and substrate *** microstructures of gradient layer have different ceramics and metal volume fraction profile along with the direction of *** profile function used to describe the gradient microstructures can be expressed in power-law or polynomial *** mechanical properties of CMGTBCs are obtained by means of microscopic *** special cases,the interactive solutions are given by Mori-Tanaka method,and the non-interactive solutions by dilute *** Young's modulus calculated by these methods are compared with those by other methods,e g,the rule of mixtures.

关键词： composite mechanical properties gradient materials

AN OVERVIEW OF THE DEVELOPMENT OF LOW GAIN FEEDBACK AND LOW-AND-HIGH GAIN FEEDBACK

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2009年第4期22卷 697-721页

作者： Zongli LIN Department of Electrical and Computer Engineering,university of virginia,P.O.Box 400473,Ch arlottesville,VA 2.904-4743,usa. Department of Electrical and Computer Engineering University of Virginia P.O. Box 400473 Charlottesville VA 22904-4743 USA

Low gain feedback refers to certain families of stabilizing state feedback gains that are pararaeterized in a scalar and go to zero as the scalar decreases to zero. Low gain feedback was initially proposed to achieve semi-global stabilization of linear systems subject to input saturation. It was then combined with high gain feedback in different ways for solving various control problems. The resulting feedback laws are referred to as low-and-high gain feedback. Since the introduction of low gain feedback in the context of semi-global stabilization of linear systems subject to input saturation, there has been effort to develop alternative methods for low gain design, to characterize key features of low gain feedback, and to explore new applications of the low gain and low-and-high gain feedback. This paper reviews the developments in low gain and low-and-high gain feedback designs.

关键词： Actuator saturation composite nonlinear feedback input saturation low-and-high gain feedback low gain feedback nonlinear control.

FLUORESCENCE　STUDIES　ON　SELF－ASSEMBLING　BEHAVIOR　OF　AMPHIPHILES　WITH　NAPHALENE－1，5－DIOXY　GROUP

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 1996年第8期7卷 735-736页

作者： Guo Wen LI Ying Qiu LIANG2(Institute of Theoretical chemistry, Jilin university, Changchun, 130023)(Department of chemistry, Nanjing university, Nanjing 210093) Institute of Theoretical chemistry Jilin University Changchun 130023 Department of chemistry Nanjing University Nanjing 210093

Fluorescene Spectra in dilute aqueous solution of a series of single chain amphiphileswith an interposed naphthalene-1,5-dioxy group were studied to elucidate the characteristic selfassembling behavior. which indicate... 详细信息

关键词： STABLE BILAYER ASSEMBLIES SINGLE-CHAIN AMPHIPHILES DILUTE AQUEOUS-SOLUTION

Perverse incentives and perverse publishing practices

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2015年第14期60卷 1225-1226页

作者： virginia Barbour Committee on Publication Ethics (COPE)

Over the past few years,publishing has becoming increasingly complex with new journals and business models,new technology,new models of peer review and new ways to collaborate and disseminate *** this,the pressure on academics to publish has become increasingly *** have always been the currency of academia—the key to tenure,grant renewal and ***,however,it is

关键词：出版物行为反常货币价值商业模式学术界

A local spin evaluation into the active site models of [2Fe2S] ferrodoxin [Fe_2S_2(SR)_4]^(2-) (R=-H, -CH_3)

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 327-334页

作者： WEI JiChong1,2, WANG Yan3 & JU GuanZhi2,3 1 Department of chemistry, Hainan Normal university, Haikou 571158, China 2 State Key Laboratory of Theoretical and Computational chemistry, Jilin university, Changchun 130023, China 3 Department of chemistry, Nanjing university, Nanjing 210093, China 1. Department of chemistry Hainan Normal University Haikou 571158 China 2. State Key Laboratory of Theoretical and Computational chemistry Jilin University Changchun 130023 China 3. Department of chemistry Nanjing University Nanjing 210093 China

To test the feasibility of local spin theory of Davidson and Clark for ferrodoxin clusters, the models [Fe2S2(SR)4]2- (R=-H, -CH3) are chosen for evaluation. This purpose is realized by calculating the local spin expectation values , 2 >, and mA and discussing the connection between these expected values and the Heisenberg spin model (HSM) and the Noodleman broken-symmetry approach. In practical calculation, the spin-unrestricted Hartree-Fock (UHF) and spin-polarized density functional theory (DFT) are used and the calculational qualities of these two methods are also discussed. In addition, the theoretical magnetic coupling constants JAB of these models are calculated by various computational schemes for comparison with both theoretical and experimental results previously reported.

关键词： local spin iron-sulfur protein model density function theory magnetic coupling constant