检索结果-南通市图书馆

MORPHOLOGICAL CHARACTERIZATION OF POLY (N-VINYLCARBAZOLE) OBTAINED WITH ASYMMETRICALLY STEREOSELECTIVE POLYMERIZATION

在线全文

学校读者我要写书评

暂无评论

chinese Journal of Polymer Science 1999年第2期17卷 159-163页

作者： Quan Su Chuan-fu Chen Yong-ming Chen fu xi PCLCC, institute of chemistry, chinese academy of sciences. beijing 100080, china chinese Acad Sci Inst Chem PCLCC Beijing 100080 Peoples R China

The morphological characterizations of poly(N-vinylcarbazole)(PVCZ) obtained by asymmetrically stereoselective polymerization were studied using x-ray diffraction pattern, DSC and GPC. The results show that the PVCZs have lower crystallinities (11.0 similar to 18.6%) and lower melting heats (2.2 similar to 7.5 J/g), but the degree of crystallinities of the PVCZ samples obtained using the organic salts (acid) with chiral or stereodifferentiating ligands are higher than that using radical and general protonic initiator. It has shown that the crystallization is directly related to the packing density of the hexagonal array of the rodlike molecules formed from the helical chain.

关键词： crystal optically active poly(N-vinylcarbazole)

OPTICALLY ACTIVE COPOLYESTERS BASED ON AxiALLY DISSYMMETRIC 1,1’-BINAPHTHALENE-2,2’-DIYL UNITS

在线全文

学校读者我要写书评

暂无评论

chinese Journal of Polymer Science 2000年第5期18卷 443-447页

作者： Chuan-fu Chen Min Ai Zhong Li Hong-wei Liu Ai-jun Gong fu xi institute of chemistry, chinese academy of sciences, beijing 100080, china chinese Acad Sci Inst Chem Beijing 100080 Peoples R China

Optically active copolyesters based on axially dissymmetric 1,1'-binaphthalene-2,2'-diyl units have been preparedand characterized by specific rotation, ^(13)C-NMR and CD spectra. The results show that the rotation signs of tribasiccopolyesters or the mixture of corresponding homopolyesters obey a three dimensional quadrant pattern. The composition ofthe copolyesters was determined from ^(13)C-NMR spectra to be triad sequence distributions and corresponding with the ratioby feed.

关键词： Optical activity Copolyester 1, 1'-Binaphthalene-2,2'-diol Diethyl tartrate

在线全文

学校读者我要写书评

暂无评论

树状分子引发苯乙烯的原子转移自由基聚合

弹性体 2001年第3期11卷 20-23页

作者：赵优良习复中国科学院化学研究所北京100080

从第 2代端羟基树状聚芳醚出发 ,合成了 2 -溴异丁酸聚芳醚酯 (G2 -Br) ,并用红外、核磁、MALDI-TOF质谱和元素分析对其进行了表征。以G2 -Br为大分子引发剂 ,在CuBr/ 2 ,2′ -联吡啶催化剂作用下引发苯乙烯的原子转移自由基聚合。考察... 详细信息

从第 2代端羟基树状聚芳醚出发 ,合成了 2 -溴异丁酸聚芳醚酯 (G2 -Br) ,并用红外、核磁、MALDI-TOF质谱和元素分析对其进行了表征。以G2 -Br为大分子引发剂 ,在CuBr/ 2 ,2′ -联吡啶催化剂作用下引发苯乙烯的原子转移自由基聚合。考察了聚合时间、单体和引发剂配比、聚合温度等因素对聚合的影响 ,合成了结构规整、分子量分布较窄的树状

关键词：树状分子树状-线型嵌段共聚物原子转移自由基聚合聚苯乙烯 ATRP 引发剂

THE SPHERULITE-LIKE STRUCTURE OF MAIN CHAIN THERMOTROPIC AROMATIC COPOLYESTERS

在线全文

学校读者我要写书评

暂无评论

chinese Journal of Polymer Science 1999年第3期17卷 245-251页

作者： Shou-xi Chen Hua-chun Zhai Yong-ze Jin institute of chemistry, chinese academy of sciences, beijing 100080, china chinese Acad Sci Inst Chem Beijing 100080 Peoples R China

A new spherulite-like structure of main chain thermotropic aromatic copolyesters formed in solution cast specimens was observed and was studied by means of polarizing microscopy, X-ray diffraction, SEM and IR spectrometry. Results indicate that the spherulite-like structure of main chain thermotropic aromatic copolyesters formed from the casting solution (phenol/Cl2CH2CH2Cl2) is not a real crystal but only a high oriented arrangement of the macromolecular chains as a spherulite. This resulted from the interaction between the needle-like crystal of phenol and the rigid mesomorphic groups of molecular chain. The parallel packing of extended copolyester molecules along the needle-like crystal of phenol leads to the formation of the spherulite-like structure.

关键词： spherulite-like structure thermotropic aromatic copolymer PET PHB

Scheme construction with numerical flux residual correction (NFRC) and group velocity control (GVC)

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12期16卷 1252-1259页

作者： MA Yanwen **and fu Dexun(LNM, institute of Mechanics, chinese academy of sciences, beijing 100080, china) [a]LNM Institute of Mechanics Chinese Academy of Sciences Beijing China

For simulating multi-scale complex flow fields like turbulent flows, the high order accurate schemes are preferred. In this paper, a scheme construction with numerical flux residual correction (NFRC) is presented. Any order accurate difference approximation can be obtained with the NFRC. To improve the resolution of the shock, the constructed schemes are modified with group velocity control (GVC) and weighted group velocity control (WGVC). The method of scheme construction is simple, and it is used to solve practical problems.

关键词： high order accurate scheme group velocity control high resolution of the shock.

CONVERGENCE OF VORTEX METHODS FOR 3-D EULER EQUATIONS

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 Computational Mathematics 2000年第3期18卷 239-250页

作者： Jia-fu Lin (institute of System Science, academy of Mathematics and System sciences, chinese academy of sciences, beijing, 100080, china School of Mathematical sciences, Peking University, beijing 100871, china) 中科院系统科学所北京 100080

Presents a study on the convergence of vortex methods for the three-dimensional Euler equations in bounded domains. Related studies on the convergence of vortex methods; Formulation of vortex methods; Convergence for ... 详细信息

关键词： Euler equations vortex methods convergence initial-boundary value problem

Synthesis of Methylated β-Cyclodextrins Derived Optically Active Poly(N-diphenylmethyl maleimide)

在线全文

学校读者我要写书评

暂无评论

chinese Chemical Letters 1997年第3期8卷 215-218页

作者： Wei Hong LIU Yong Ming CHEN Chuan fu CHEN and fu xi (institute of chemistry, chinese academy of sciences, beijing 100080 ) chinese ACAD SCI INST CHEMBEIJING 100080PEOPLES R CHINA

The methylated β-cyclodextrins derived optically active polymers are firs synthesized through asymmetric polymerization of N-diphenylmethyl maleimide with lithium salt of heptakis(2,6-O-dimethyl) β-cyclodextrin (DM-β-CD) as an initiator. The resulting polymers show negative specific rotation which is opposite in sign to that of DM-β-CD. The asymmetric induction is further confirmed by circular dichroism. The structure is characterized by IR and NMR spectroscopies

关键词： Cyclodextrins Derived Optically Active Poly Li Chen N-diphenylmethyl maleimide Synthesis of Methylated

ON SELF-ABSORPTION CORRECTION IN EXCIMER FLUORESCENCE MEASUREMENTS OF POLYMER SOLUTIONS

在线全文

学校读者我要写书评

暂无评论

chinese Journal of Polymer Science 2000年第5期18卷 465-468页

作者： xi-gao Jin Zhong Jiang Ming Ni Feng-lian Bai Ren-yuan Qian institute of chemistry, chinese academy of sciences, beijing 100080, china chinese Acad Sci Inst Chem Beijing 100080 Peoples R China

The effect of self absorption on the ratio of excimer to monochromophore emission intensities, I-e/I-m, has been explored by experimentally changing the solution layer thickness of the emission light path traversed in the solution in the right-angle geometry. The result shows that data obtained by front-face geometry are better than those obtained by right-angle geometry even after correction to zero solution thickness. The correction formula based on geometric optics given by Tsai and Torkelson is not adequate.

关键词： excimer fluorescence self absorption polystyrene solution

Ionic effective radii under high-temperatures state

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 1997年第15期42卷 1265-1268页

作者： fu Zhengmininstitute of Physics, chinese academy of sciences, beijing 100080, china institute of Physics Chinese Academy of Sciences Beijing 100080 China

REFERENCES [1, 2] prove that ionic radii will increase or decrease with temperature rising orlowering. If the ionic radii at room temperature are known, many phenomena of the ioniccompounds occurring at room temperature can be explained. Also if the ionic radii at high tem-perature are known, many phenomena of the ionic compounds occurring at high temperaturecan also be explained. Therefore, to calculate the effective radii of ions at high temperature isconsidered of great significance. For example, the 'investigation of KIO3-CsIO3

关键词： high temperature ionic effective radii ionic compounds.