检索结果-南通市图书馆

STUDIES ON THE PERMEABILITY OF P VC/EBBA OVERLAPPED ULTRATHIN COMPOSITE MEMBRANES MODIFIED BY PLASMA-polymerIZATION WITH FLUOROCARBON MONOMERS

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of polymer science 1989年第2期7卷 124-131页

作者：傅秀城金熹高梶山千里 Institute of chemistry Academia SinicaBeijing.China department of Applied chemistry Faculty of EngineeringKyushu UniversityFukuokaJapan

The PVC/EBBA ultrathin composite membranes with thickness of about 100 nm were prepared by spreading the solution on water surface. The overlapped composite membrane showed a characteristic aggregation structure in which the polymer matrix exists as a three-dimensional spongy network and the liquid crystal domains werc observed. Tne surface modification for the overlapped membranes was carried out by means of plasma-polymerization with the monomers of fluorocarbon compounds. Both Arrhenius plots of permeability coefficients for oxygen ((?)_O_2. in the membrane samples before and after modification showed significant increase in the vicinity of the T_(KN) of EBBA.

关键词： Membrane Gas Permeation Liquid crystal Plasma polymerization Surface modification Fluorocarbon compound.

THE MORPHOLOGY AND STRUCTURE OF POLYETHYLENE TEREPHTHALATE SPHERULITES

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of polymer science 1984年第2期 169-176页

作者：李历生 department of chemistry peking university beijing

The morphology and structure of three types of normal and abnormal spherulites of polyethylene terephthalate cast from solution in dimethylphthalate were studied by polarizing microscopy, transmission electron microscopy and electron diffraction techniques. In the normal negative spherulites the [0]~* direction is parallel to the radius direction. In the normal positive spherulites the radius direction is parallel to the [6]~*. In the abnormal PET spherulites the Maltese cross extinction pattern in the polarizing microscope under crossed polars is oriented at 45°to the polars and there are concentric extinction rings around the center of the spherulite. Electron diffraction pattern indicates that [2.~* is parallel to the radius of the spherulite and this explains the observed extinction pattern, in the abnormal spherulite.

关键词： PET THE MORPHOLOGY AND STRUCTURE OF POLYETHYLENE TEREPHTHALATE SPHERULITES

Effects of Steric Conformations of Peptides Containing Guanidium Groups on Molecular Recognition of RNA

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Effects of Steric Conformations of Peptides Containing Guani...

STUDIES ON THE PEROXYDISULFATEALIPHATIC AMINE INITIATION SYSTEMS

8th Chinese International Peptide Symposium

作者： Hang ZHANG, Meirong HAD, Yunhua YE, Ming YANG National Research Laboratory of Natural and Biomimetic Drugs, peking university, {2. 100083.{3. department of chemistry, peking university, {2. 100087,{3.

Short peptides containing the basic region of the HTV-1 Tat protein bind specifically to a bulged region in TAR RNA. The aim of this study was to observe peptides containing guanido as inhibitors of Tat binding to RNA. The effect of peptides containing guanido on DNA and RNA was investigated by using polymers Poly (dA)(Poly (dT) and PolyA(PolyU as test system for analysis of nucleic acid binding strength and selectivity. Tm experiment showed that the compounds had a totally different effect on DNA and RNA, and CD spectra also observed the changes of RNA

关键词：

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 in china,Ser.B 1987年第9期30卷 897-906页

作者：郭新秋丘坤元冯新德 department of chemistry peking university

The effect of some types of water-soluble aliphatic amines on the polymerization of acrylamide initiated by peroxydisulfate has been investigated in this paper. It was found that the primary and secondary aliphatic amines enhanced the rate of the polymerization effectively as well as tertiary amines and the promoting effect of these amines varied with their different structures. A new method of detecting the aliphatic amine end-group of the polymer has been developed, i.e. 'CTC Spectrum Method'. The kinetic equation and overall activation energies of the polymerization have been determined and the initiation mechanism of peroxydisulfate-aliphatic amine system was proposed.

关键词： TMEDA KPS STUDIES ON THE PEROXYDISULFATEALIPHATIC AMINE INITIATION SYSTEMS

铈离子与乙酰苯胺及其衍生物引发丙烯酰胺聚合动力学的研究

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

高分子学报 1989年第3期 355-362页

作者：丘坤元王伟北京大学化学系

以铈离子和酰苯胺引发体系进行丙烯酰胺的聚合,研究了不同结构酰苯胺对聚合的影响。在H_2.-CH_3.N(3.1)介质中聚合时,乙酰对甲苯胺对聚合的促进作用最为明显,聚合速度可提高一个数量级。测定了聚合反应的表观活化能和聚合动力学方程、... 详细信息

以铈离子和酰苯胺引发体系进行丙烯酰胺的聚合,研究了不同结构酰苯胺对聚合的影响。在H_2.-CH_3.N(3.1)介质中聚合时,乙酰对甲苯胺对聚合的促进作用最为明显,聚合速度可提高一个数量级。测定了聚合反应的表观活化能和聚合动力学方程、由聚合物的原子发射光谱,UV光谱和端基测定,提出了聚合反应机理。

关键词：引发剂铈/乙酰苯胺丙烯酰胺

INFLUENCE OF COMPOSITIONAL HETEROGENEITY ON MORPHOLOGY AND PROPERTIES OF SEGMENTED COpolymerS

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of polymer science 1988年第1期6卷 64-74页

作者：胡世如徐懋张兴元马德柱罗筱烈 Institute of chemistry Academia Sinica beijing department of Applied chemistry university of science and Technology of{2. Hefei

Polyethylene terephthalate(PET)/polycaprolactone(PCL) segmented copolymers with different hard segment contents and a blend of two of them were studied by using DSC, WAXS, TEM and IR techniques and dynamic mechanical, stress-strain and isothermal crystallization measurements. Emphasis was laid on the studies of influence of compositional heterogeneity on the morphology and properties of these segmented copolymers. It was found that the solution cast specimens of the more heterogeneous sample exhibit better segregation of segments, high crystallinity and melting temperature. They have higher thermal stability of mechanical properties at small deformations. However, they are less stable against large deformations and may become softer than the more homogeneous ones.

关键词： Segmented polyester eompositional heterogeneity morphology mechaical properties.

THE chemistry OF NANOSCALE ORGANOIMIDO DERIVATIVES OF POLYOXOMETALATES

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 CHEMISTRY OF NANOSCALE ORGANOIMIDO DERIVATIVES OF POLYOX...

MESOMORPHIC BEHAVIOR AND MULTIPLE MELTING TRANSITION OF AROMATIC POLYESTER FRACTIONS

Asia Conference on Nanoscience and Nanotechnology Abstracts Book

作者： PINGFAN WU qiANG Li YONGGE WEI YUAN WANG PING WANG HONGYOU GUOState Key Laboratory for Structural chemistry of Unstable and Stable Species College of chemistry and Molecular Engineering {3. university beijing 100871 chinadepartment of Bioengineering Hubei university of Technology Wuhan 43.068 china department of chemistry beijing university of Chemical and Technology beijing 10002. china

＜正＞ Organoimido derivatives of polyoxometalates play very important roles in the supramolecular chemistry and chemistry of materials based on polyoxometalates because they are valuable building blocks for constructing novel nanostructured organic-inorganic hybrid materials with unique catalytic, photo and electronic properties. However, their synthetic chemistry has not been well-developed since the first work reported by Maatta et al. Three years ago, one of us, together with his coworkers at UMKC, developed an efficient and convenient reaction protocol to give the arylimido derivatives of hexamolybdate, [Mo6O19]{3., and pentatungstenmolybdate, [MoW5O19]{3., using a carbodiimide, i.e., DCC （N,N’-dicyclohexylcarbo- diimide） as the dehydrating agent, and also found that the derivatives with iodo and ethynyl groups could undergo carbon-carbon coupling reactions in the presence of Pd catalyst. In this paper, we will give a brief review on this work and introduce our recent progresses in the synthetic and crystal structural chemistry of nanoscale organoimido derivatives of polyoxometalates.

关键词：

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

Chinese Journal of polymer science 1988年第4期6卷 337-344页

作者：刘小平胡世如张贤施良和徐懋周其凤段晓青 Institute of chemistry Academia Sinica department of chemistry peking university peking university {2.

Fractions of an aromatic polyester have been studied by DSC, polarizing microscopy, SALS and WAXS techniques. The intrinsic viscosity of the samples in tetrachloroethane is ranging from 0.197 to 0.591dl / g. All the samples exhibit enantiotropic liquid crystal behavior, and the thermal stability of mesophase decrease withlowering the molecular weight of the fractions. The glass transition temperature keeps almost constant for allthe samples, however its value for supercooled mesophase is about 2.~C lower than that for amorphous *** melting phenomenon was also found for samples crystallized from their mesophases and was similarto that observed for nonliquid crystal forming polymers.

关键词： Aromatic polyester fractions Thermotropic liquid crystal DSC

Manipulating guest-responsive spin transition to achieve switchable fluorescence in a Hofmann-type framework

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 {2. 2024年第10期67卷 3339-3346页

作者： Xue-Ru Wu Shu-qi Wu Zhi-Kun Liu Ming-Xing Chen Jun Tao Osamu Sato Hui-Zhong Kou Engineering Research Center of Advanced Rare Earth Materials(Ministry of Education) Department of ChemistryTsinghua UniversityBeijing 100084China Institute for Materials chemistry and Engineering&IRCCS Kyushu University744 MotookaNishi-kuFukuoka 819-0395Japan Key Laboratory of Cluster science of Ministry of Education School of Chemistry and Chemical EngineeringLiangxiang CampusBeijing Institute of TechnologyBeijing 102488China Analytical Instrumentation Center College of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China

The change of fluorescence emission manipulated by spin state transition attracts considerable attention owing to its potential applications in magneto-optical switching ***,we report two two-dimensional(2.)Hofmann-type spin crossover(SCO)metal-organic frameworks(MOFs)[Fe^(Ⅱ)(PNI)_(2.{Ag^(Ⅰ)(CN)_(2.}_(2.]·CHCl_(3.(3.g·CHCl_(3.)and[FeⅡ(PNI)_(2.{AuⅠ(CN)_(2.}_(2.]·CHCl_(3.(3.u·CHCl_(3.)based on the fluorescent ligand N-(4-pyridylmethyl)-1,8-naphthalimide(PNI).Both complexes exhibit interesting SCO behaviors switched by guest solvent molecules,namely three-step transitions for the solvated complexes and complete onestep hysteretic SCO for the desolvated ones,verified by temperature-dependent magnetic susceptibility measurements,Mossbauer spectra,structural analyses,and differential scanning calorimetry ***,temperature-dependent fluorescence spectra exhibit double peaks(monomer and excimer emission)with both emission peaks change consistent with the change in SCO properties during the solvent molecule *** this study,we integrated guest-responsive SCO behavior into MOFs to manipulate the multistability of spin state and fluorescence switching,providing a rational strategy for the development of stimuli-responsive multifunctional materials.

关键词： spin crossover fluorescence multifunctional materials metal-organic frameworks Hofmann-type