检索结果-南通市图书馆

Study on the drug resistance and the binding mode of HIV-1 integrase with LCA inhibitor

在线全文

学校读者我要写书评

暂无评论

Science china chemistry 2007年第5期50卷 665-674页

作者： HU JianPing1,2. CHANG Shan1, CHEN WeiZu1 & WANG CunXin1 1 college of life Science and Bioengineering, Beijing {2. of Technology, Beijing 10002., china 2.Department of chemistry & life sciences, Leshan Normal {2., Leshan 614004, china college of life Science and Bioengineering Beijing University of TechnologyBeijing 100022China Department of chemistry & life {2. Leshan Normal UniversityLeshan 614004China

Human immunodeficiency virus type 1 (HIV-1) integrase (IN) is an essential enzyme in the lifecycle of this virus and also an important target for the study of anti-HIV drugs. The binding mode of the wild type IN core domain and its G140S mutant with L-Chicoric acid (LCA) inhibitor were investigated by using multiple conformation molecular docking and molecular dynamics (MD) simulation. Based on the binding modes, the drug resistance mechanism was explored for the G140S mutant of IN with LCA. The results indicate that the binding site of the G140S mutant of IN core domain with LCA is different from that of the core domain of the wild type IN, which leads to the partial loss of inhibition potency of LCA. The flexibility of the IN functional loop region and the interactions between Mg2. ion and the three key residues (i.e., D64, D116, E152. stimulate the biological operation of IN. The drug resistance also lies in several other important effects, such as the repulsion between LCA and E152.in the G140S mutant core domain, the weakening of K159 binding with LCA and Y143 pointing to the pocket of the G140S mutant. All of the above simulation results agree well with experimental data, which provide us with some helpful information for designing the drug of anti-HIV based on the structure of IN.

关键词： molecular docking, MD simulation, HIV-1 IN, drug design

Effects of water phase concentration on the emulsion polymerization of polyaniline

在线全文

学校读者我要写书评

暂无评论

Journal of central south {2. of Technology 2001年第2期8卷 140-142页

作者： PAN Chun yue 1,CHEN Zhen hua 2.HUANG Yong li 1,HUANG Ke long 1 (1.college of chemistry and Chemical Engineering, {2. south university, Changsha 410083, china 2.Department of Materials Science and Engineering, {2. south university, Cha college of chemistry and Chemical Engineering Central South University Changsha China Department of Materials Science and Engineering Central South University Changsha China

The emulsion polymerization of aniline in three phase system of xylene functionalized protonic acid water was carried out using (NH 4) 2. 2. 4 as oxidant. The influences of water phase concentration on the viscosity, conductivity, transmittance of polyaniline(PAN) latex and its powders were studied. The results show that the properties of PAN prepared through the emulsion polymerization are influenced by the amount of water used in the polymerization. The morphology of PAN varies with the water phase concentration used in the polymerization, which may result in the change of properties of PAN latex and its powders. When the volume fraction of water (φ) is about 2.% 30%, the prepared PAN powder has higher conductivity, and the PAN latex has appropriate viscosity and particle size. The consumption of xylene was reduced at high φ value.

关键词： polyaniline emulsion polymerization water concentration property

Knowledge-reuse-oriented Product Modeling and Knowledge Management in Digital Design

在线全文

学校读者我要写书评

暂无评论

武汉理工大学学报 2006年第S1期28卷 150-155页

作者： ZHANG Jinsong (college of Management,south-{2. university for nationalities,Wuhan 430073, china) college of Management South-Central University for NationalitiesWuhan 430073China

Mostly product design knowledge and experience exists in design handbook or expert’s brain. During design process,designer has to refer to many handbooks and design materials,and design solution is hard to be reused. In order to deal with these deficiencies in digital design,this paper focuses on knowledge-reuse-oriented product modeling and knowledge management. Design knowledge is used to guide design process,and it is embedded into product model along with design process. Through analyzing design process,mechanical product knowledge is classified into four basic types that include calculation formula,design rule,engineering check and parameter spectrum etc. In order to manage and encapsulate design knowledge the concept of knowledge component(KCOM) is proposed. Design knowledge base can be organized as a hierarchy tree of KCOM. Knowledge reuse in KCOM level is the reuse of whole object in knowledge base,and knowledge reuse in item level is the reuse of basic knowledge type. Finally knowledge reuse approaches between knowledge base and CAD system is presented.

关键词： digital design knowledge reuse product modeling design knowledge knowledge management

Structures and stability of isomers of[Si,N,N,P]system

在线全文

学校读者我要写书评

暂无评论

Science china chemistry 2004年第2期47卷 98-105页

作者： KAN Wei1, YU Haitao1, LI Mingxia1, FU Honggang1,2.& SUN Jiazhong1,2.1. college of chemistry and Chemical Engineering, Heilongjiang {2., Harbin 150080, china 2. State Key Laboratory of Theoretical and Computational chemistry, Institute of Theoretical chemistry, Jilin {2., Changchun 13002., china college of chemistry and Chemical Engineering Heilongjiang University Harbin China State Key Laboratory of Theoretical and Computational chemistry Institute of Theoretical Chemistry Jilin University Changchun China

Some stationary points on the potential energy surface of [Si, N, N, P] system were located at the B3LYP/6-311G(d) and QCISD(t)/6-311+G(2.f)(single-point) levels of theory, while the isomerization, structures, and stability of these obtained isomers were suggested. The computed results indicate that only four-membered ring isomer SiNPN(E1, 2.'), which possesses butterfly-like structure and Si-P cross bonding, is kinetically stable in all optimized isomers. Other isomers may be considered as kinetically unstable towards isomerization or dissociation because of the corresponding smaller reaction barriers. Furthermore, the present paper also proposes electronic and geometric structures, vibrational frequencies and the corresponding vibrational modes, dipole moments, and rotational constants of isomer E1. To make use of the computed results, we can clearly know that the reaction pathway via an intermediate E3 (SiNPN) is the most favorable channel producing isomer E1 from fragments SiN(2.) and PN (1Σ), which have been well characterized in space, and thus, isomer E1 can be considered as a candidate for interstellar observation. The reaction enthalpy of SiN(2.) + PN(1Σ)→ E1 and the standard enthalpy of formation of isomer E1 are 2.5.2. and 457.99 kJ/mol, respectively, at 2.8.15 K. Keywords potential energy surface - [Si,N,N,P] system - isomerization - kinetic stability

关键词： potential energy surface, [Si,N,N,P] system, isomerization, kinetic stability.

Sensitive Determination of DNA by RLS Enhancement of Metal Ions

在线全文

学校读者我要写书评

暂无评论

Wuhan university Journal of Natural sciences 2004年第2期9卷 234-238页

作者： Huang Jian-ping 1,2. Chen Fang 1, Ai Xin-ping 1, He Zhi-ke 1 1. college of chemistry and Molecular {2., Wuhan university, Wuhan 430072. Hubei, china 2. Department of Environmental Engineering, Hubei Agricultural college, Jingzhou 43402., Hubei, china college of chemistry and Molecular {2. Wuhan University Wuhan Hubei China Department of Environmental Engineering Hubei Agricultural College Jingzhou Hubei China

The interactions between metal ions and DNA have been studied by the resonance light scattering (RLS) spectra. In the acidic condition, the RLS signals of metal ions, especially the transition metal ions in group IB and IIB, were increased by DNA. And it is found that the enhancement of RLS signals is linear to the concentration of DNA, so the RLS method for DNA determination was proposed in the presence of Cu2.. On the optimum conditions, the linear range and the detect limit of ctDNA is 4×10?8–4×10?6 g· mL?1 and 1. 13×10?8 g·mL?1, respectively. The proposed method is successfully applied to determine the extracted plasmid DNA ofBacillus subtilis DB104. Key words resonance light scattering - DNA - metal ions CLC number O 657.3 Foundation item: Supported by National Natural Science Foundation of china (2.2.502.) and the National Key Basic Research and Development Program (973 Program 2.02.B2.1800).Biography: Huang Jian-ping(1964-), male, Associate professor, research direction: bioanalysis.

关键词： resonance light scattering DNA metal ions

Extended detection range for an optical enzymatic glucose sensor coupling with a novel data-processing method

在线全文

学校读者我要写书评

暂无评论

Science china chemistry 2010年第6期53卷 1385-1390页

作者： GUO GuangMei1,WANG XuDong2.ZHOU TingYao2.& CHEN Xi2.1college of sciences,Hebei {2. of Science and Technology,Shijiazhuang 050018,china 2.epartment of chemistry,college of chemistry and Chemical Engineering,Xiamen {2. Key Laboratory of Analytical sciences of Xiamen {2.,Xiamen 361005,china college of sciences Hebei University of Science and Technology Shijiazhuang China Department of chemistry College of Chemistry and Chemical Engineering Xiamen University Key Laboratory of Analytical sciences of Xiamen university Xiamen China

A new data-processing method was established and applied for optical enzymatic glucose sensing,in which oxygen and glucose were simultaneously *** oxygen level remaining in the detection system,which was equal to the difference between the initial and consumed oxygen concentrations,could be measured using fluorescent oxygen indicators immobilized in the sensing *** was deduced that the ratio of I0 and I was inversely proportional to glucose concentration,where I0 is the maximum fluorescence intensity in various glucose solutions,and I is the fluorescence intensity at various concentrations of *** the new data-processing method,the detection range of the calibration curve method was extended from 0 to 1.2.mmol L-1,which was enlarged about 2.3 folds over that in ordinary *** prepared glucose sensor could be directly applied to detect high concentrations of glucose.

关键词： optical glucose sensor glucose oxidase extended detection range

Synthesis and properties of nickel borate acylate as a new rubber-steel cord adhesion promoter

在线全文

学校读者我要写书评

暂无评论

Journal of central south {2. of Technology 2001年第4期8卷 244-248页

作者： LI Xiao ru 1,NIE Xi du 2.WU Hai ying 1,CHENG Ben cheng 1 (1 college of chemistry and Chemical Engineering, {2. south university, Changsha 410083, china 2.Hengyang Branch of Hunan university, Hengyang 412.00, china) college of chemistry and Chemical Engineering Central South University Changsha China Hengyang Branch of Hunan university Hengyang China

The synthetic method of nickel borate acylate (NBA), a kind of rubber steel cord adhesion promoter (AP), through nickel carbonate, borate and mixed carboxylic acid was studied. The preparation of nickel carbonate could be performed through reaction of nickel sulfate with sodium carbonate in aqueous solution, in which fractional conversion of nickel was more than 99.9%. The mixed nickel carboxylate was prepared by the reaction of nickel carbonate with isooctanoic acid and acetic acid, under strong stirring for 2.h, the mole ratio of these chemicals were 1∶1∶1.1 respectively, and water should be removed completely by adding of inert organic solvent after reaction was finished so as to avoid hydrolysis of tributyl borate in the second reaction. NBA was synthesized by reaction of mixed nickel carboxylate with tributyl borate under strong stirring at 2.0 2.0 ℃ for 6 h. By detection and comparison with 680C product from Manobond Company of England, the NBA synthesized through isooctanoic acid and tributyl borate was very similar to product 680C in IR data, 300% fixed extension strength, tensile strength, hardness and cure curve, and was slightly lower than those of product 680C in tensile failure extensibility and hot air aging. The experimental results show that the prepared NBA can be used as rubber steel cord AP.

关键词： nickel borate acylate adhesion promoter nickel carbonate borate

Proton Conducting Composite Membranes from Sulfonated Polyether Ether Ketone and SiO_2

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) 2009年第1期24卷 95-99页

作者：张高文 college of chemistry and Environment Hubei University of Technology

Proton conducting composite membranes from sulfonated polyether ether ketone and SiO2.for direct methanol fuel cell （DMFC） application were prepared with sulfonated polyether ether ketone（SPEEK） and tetracethoxy silane（TEOS） by sol-gel method. The covalent crosslinking structure was formed between —SO3H of SPEEK via SiO2. The SEM images show that the interfacial compatibility of SPEEK and SiO2.is improved obviously and SiO2.disperses uniformly in the polymer matrix and the particle diameter of SiO2.does not exceed 40 nm. The proton conductivity of composite membranes decreases slightly compared with the SPEEK membrane while the methanol permeability and swelling of composite membrane are improved remarkablely owing to covalent cross-linking between —SO3H and SiO2..

关键词： direct methanol fuel cell sulfonated polyether ether ketone sol-gel method proton conductivity methanol permeability

Pollution characteristics of atmospheric fine particles and their secondary components in the atmosphere of Shenzhen in summer and in winter

在线全文

学校读者我要写书评

暂无评论

Science china chemistry 2006年第5期49卷 466-474页

作者： NIU Yuwen1,2.HE Lingyan1,2.HU Min2.ZHANG Jing2.& ZHAO Yunliang2.1. Shenzhen Graduate School of Peking university,Shenzhen 518055,china 2. State Joint Key Laboratory of Environmental Simulation and Pollution Control,{2. of Environmental sciences,Peking university,Beijing 100871,china Shenzhen Graduate School of Peking university Shenzhen China State Joint Key Laboratory of Environmental Simulation and Pollution Control College of Environmental Sciences Peking University Beijing China

Two field measurements for atmospheric fine particles were conducted in Baoan district of Shenzhen during the summer and winter in 2.04. Totally 30 sets of 2. h samples were collected, and then the mass concentrations and chemical compositions were determined. The seasonal varia- tions and secondary pollution characteristics of fine particles during the sampling periods were dis-cussed with meteorological factors. The results show that seasonal variations of atmospheric particles are significant in Shenzhen. The average mass concentrations of PM2.5 and PM10 in summer were 35 μg·m-3 and 57 μg·m-3, respectively, and those in winter were 99 μg·m-3 and 135 μg·m-3, respec-tively. The concentrations of both PM2.5 and PM10 in winter increased 184% and 137%, respectively, compared to those in summer. PM2.5 accounted for 61% and 75% of PM10 in summer and in winter, respectively, indicating severe fine particle pollution in Shenzhen. During the summer and winter sampling periods, the mean OC/EC ratios were 3.4 and 1.6, respectively. The estimated secondary organic carbon (SOC) averagely accounted for 56% and 6% of the total OC in summer and in winter, respectively, which implies a major contribution of SOC to OC in summer. During the continuous high temperature period in summer, both the concentrations and fractions of secondary aerosol compo-nents in PM2.5 were highly elevated, suggesting severe secondary pollution again. The prevailing wind was from south china Sea in summer, and the air quality was good. The prevailing wind in winter was from china's Mainland to the north, and the polluted air mass led to poor air quality.

关键词： PM2.5, mass concentration, secondary pollution, seasonal variation, Shenzhen.