检索结果-南通市图书馆

MgCl_2·6H_2O-BASED ZIRCONOCENE CATALYST FOR ETHYLENE POLYERIZATION

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 185-188页

作者： Shi-jing Xiao Hui Yao Ke-quan Peng institute of Chemistry, chinese academy of sciences, beijing 100080,{3. institute of Chemistry Chinese Academy of Sciences Beijing 100080 China

Several supported zirconocene catalysts were prepared by using MgCl_2·6H_2O as a precursor forproducing an active support. Such catalysts combined with methylaluminoxane (MAO) obtained by reactingMgCl_2·6H_2O with AlMe_3.show good activity for ethylene polymerization similar to that of anhydrousMgCl_2 supported zirconocene catalyst.

关键词： MgCl_2.6H_2O, Supported zirconocene catalyst Ethylene polymerization

An efficient chiral synthesis of (R)-N-[3.acetyl-4-(2-hydroxy-3.isopropylamino-propoxy)phenyl]-butanamide with high enantioselectivity

在线全文

学校读者我要写书评

暂无评论

Science china Chemistry 2009年第8期52卷 1216-1219页

作者： WANG NaiXing1,2 & TANG XinLiang1,3.1 Technical institute of Physics and Chemistry,chinese academy of {3.,beijing 100080,china 2 College of Chemistry and Chemical Engineering,Graduate University of chinese academy of sciences,beijing 100049,china 3.School of Chemical Engineering and Environment,beijing institute of Technology,beijing 100081,china 1. Technical institute of Physics and Chemistry Chinese Academy of Sciences Beijing 100080 China 2. College of Chemistry and Chemical Engineering Graduate University of Chinese Academy of Sciences Beijing 100049 China 3. School of Chemical Engineering and Environment Beijing Institute of Technology Beijing 100081 China

R-Enantiomer of the β-receptor antagonist N-[3.acetyl-4-(2-hydroxy-3.isopropylamino-propoxy)phenyl] butanamide with high enantioselectivity was synthesized from cheap starting materials and enantiopure chiral reagent through an efficient,convenient and practical synthetic *** product was detected by 1H NMR,13. NMR,and MS,and the enatiomeric excess was determined by chiral HPLC analysis using a chiracel AD-H column.

关键词： chiral synthesis enantioselectivity enatiomeric excess chiral HPLC analysis

Cloning and characterization of a new actin gene from Oryza sativa L.

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2004年第10期14卷 27-34页

作者： LIANG Weihong,TANG Chaorong and WU Naihu (institute of Genetics and Developmental Biology,chinese academy of {3.,beijing100080,china) chinese Acad Sci Inst Genet & Dev Biol Beijing 100080 Peoples R China

Using Rho family member osRACD as bait,a new member of actin gene family-Act was isolated from Oryza sativa by yeast two-hybrid *** full-length cDNA was cloned with5′RACE technology,which contains an open reading frame of113.bp with a predicted protein of3.7amino *** alignment revealed96%to81.8%identities with some known actin proteins in *** method of bioinformatics was used to analyze the protein modification sites,structure and evolution of the *** blot analysis showed that Act is a single-copy gene in the *** result of RT-PCR showed it is ubiquitously expressed in root,shoot,callus and panicle in a temporal *** relationship between Rho family and actin family in evolution and function was also studied.

关键词： rice panicle yeast two-hybrid actin Rho gene clone

Explicit analytical solutions of the anisotropic Brinkman model for the natural convection in porous media(Ⅱ)

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(Physics,Mechanics & Astronomy) 2005年第4期48卷 422-430页

作者： CAI Ruixian1, GOU Chenhua1, 2 & ZHANG Na1 1. institute of Engineering Thermophysics, chinese academy of sciences, beijing 100080,{3. 2. Graduate School, chinese academy of sciences, beijing 100080,{3. 1. institute of Engineering Thermophysics Chinese Academy of Sciences 100080 Beijing China 2. Graduate School Chinese Academy of Sciences 10080 Beijing China

Some algebraically explicit analytical solutions are derived for the anisotropic Brinkman model―an improved Darcy model―describing the natural convection in porous media. Besides their important theoretical meaning (for example, in analyzing the non-Darcy and anisotropic effects on the convection), such analytical solutions can be the benchmark solutions that can promote the development of computational heat and mass transfer. Some solutions considering the anisotropic effect of permeability have been given previously by the authors, and this paper gives solutions including the anisotropic effect of thermal conductivity and the effect of heat sources.

关键词： explicit analytical solution, porous medium, natural convection, Brinkman model, anisotropic.

ON A CELL ENTROPY INEQUALITY OF THE RELAXINGSCHEMES FOR SCALAR CONSERVATION LAWS

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2000年第1期18卷 69-74页

作者： Hua-zhong Tang Hua-mo Wu(State Key Labomtory of Scientific and Engineering Computing, institute of ComputationalMathematics, chinese academy of sciences, beijing 100080,{3.) 中科院计算数学所科学与工程计算国家重点实验室北京 100080

Presents a study which examined a cell entropy inequality for a class of local relaxation approximation relaxing scheme for scalar conservation laws. Way to obtain the scheme; Use of numerical entropy condition for th... 详细信息

关键词： hyperbolic conservation laws the relaxing schemes cell entropy inequality

The age of the plant fossil assemblage in the Liuqu Conglomerate of southern Tibet and its tectonic significance

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1期16卷 55-64页

作者： FANG Aimin1, YAN Zhen1, LIU Xiaohan2, PAN Yusheng1, LI Jiliang1, YU Liangjun1, HUANG Feixing2 and TAO Junrong3.(1.Laboratory of Lithosphere Tectonic Evolution, institute of Geology and Geophysics, chinese academy of sciences, beijing 100029,{3. 2. institute of Tibet Plateau Research, chinese academy of sciences, beijing 100085,{3. 3. institute of Botany, chinese A cademy of sciences, beijing 100093.{3.) Laboratory of Lithosphere Tectonic Evolution Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China institute of Tibet Plateau Research Chinese Academy of Sciences Beijing 100085 China institute of Botany Chinese A-cademy of Sciences Beijing 100093 China

The Liuqu Conglomerate, situated to the south of Yarlung Tsangbo Suture Zone (YTSZ), is a suit of molasse formed in a foreland basin of the Himalayan orogenic belt after the collision between the two plates of the Indian and Eurasion, It is of great significance in constraining the younger limit time of the collision of the two plates and providing stratigraphic evidence to reveal the post-colli sional tectonic evolution and uplifting history of the Tibet plateau. However, the age of this molasse suit and its correlation to other synchronous strata distributed in southern Tibet have been in great disputes for a long time. Especially in recent years, argues on its ages are growing violently with the recognition of the great sedimentary tectonic significances of this molasse. During the field work carried out recently on this molasse suit, a lot of plant fossils were found preserved in fairly good conditions in the upper part of this strata, which is of great help in determining its age. By identification, the assemblage of the plant fossils belongs to a tropic to subtropic flora developed in the southern margin of the Northern Hemisphere supercontinent during the Middle to Later Eocene, which can provide good constraint on its formation age. This paper is to give a brief introduction of the plant assemblage and its age, and to discuss their tectonic significances.

关键词： Liuqu conglomerate plant fossils age Eocene Tectonic implications.

SYNTHESIS OF NOVEL SOLUBLE AROMATIC POLYPYROMELLITIMIDE CONTAINING ORDERED 1,2,4-TRIAZINE IN THE MAIN CHAIN

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

chinese Journal of Polymer Science 2002年第3期20卷 219-224页

作者： Xiao-bing Yi Guo-shi Wu Feng-cai Lu Department of Chemistry Tsinghua University, beijing 100084 china institute of Chemistry{3., beijing 100080, china Tsing Hua Univ Dept Chem Beijing 100084 Peoples R China chinese Acad Sci Inst Chem Beijing 100080 Peoples R China

A new heat-resistant, soluble polymer, poly(phenyl-1,2,4-triazine imide), has been prepared via a two-step method of polycondensation of N,N'-bis(4-benzil)pyromellitimide and terephthalamidrazone in cresol, followed by curing at higher temperature. The rigid 1,2,4-triazine group increases the solubility of the polyimide so that the polymer is soluble in cresol, N-methyl-2-pyrrolidone (NMP), trifluoroacetic acid and concentrated sulfuric acid, etc. Thermogravimetric analysis (TGA) indicates that this novel polyimide has good thermal stability with a high decomposition temperature of 447degreesC in air and of 423.degreesC in N-2, It has a tensile strength of 107.4 MI'a with an elongation at break of around 7.6%.

关键词： polyimides N,N '-bis(4-benzil)pyromellitimide rigid-rod group 1,2,4-triazine

A new class of three-variable orthogonal polynomials and their recurrences relations

在线全文

学校读者我要写书评

暂无评论

Science china Mathematics 2008年第6期51卷 1071-1092页

作者： SUN JiaChang State Key Laboratory of Computer Science,R&D Center for Parallel Computing,institute of software,chinese {3. of sciences,beijing 100080,china State Key Laboratory of Computer Science R & D Center for Parallel Computing Institute of Software Chinese Academy of Sciences Beijing 100080 China

A new class of three-variable orthogonal polynomials, defined as eigenfunctions of a second order PDE operator, is studied. These polynomials are orthogonal over a curved tetrahedron region, which can be seen as a mapping from a traditional tetrahedron, and can be taken as an extension of the 2-D Steiner domain. The polynomials can be viewed as Jacobi polynomials on such a domain. Three-term relations are derived explicitly. The number of the individual terms, involved in the recurrences relations, are shown to be independent on the total degree of the polynomials. The numbers now are determined to be five and seven, with respect to two conjugate variables z, $ \bar z $ and a real variable r, respectively. Three examples are discussed in details, which can be regarded as the analogues of the Chebyshev polynomials of the first and the second kinds, and Legendre polynomials.

关键词： 3.D PDE eigen-problem three-variable Chebyshev polynomials Legendre polynomial Jacobi polynomials recurrence relations 65N25 42C05 3.C45

SYNTHESIS AND POLYMERIZATION OF TRI(2-PYRIDYL)METHYL METHACRYLATE

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 295-298页

作者： Chuan-fu Chen Yong-hong Yang Fu Xi institute of Chemistry, chinese academy of sciences, beijing 100080,{3. chinese Acad Sci Inst Chem Beijing 100080 Peoples R China

A novel methacrylate monomer with bulky side group, tri(2-pyridyl)methyl methacrylate (Tr2PyMA), was synthesized and polymerized. The polymer obtained by radical polymerization exhibits high isotactic tacticity.

关键词： optical activity tri(2-pyridyl)methyl methacrylate