检索结果-南通市图书馆

Science china chemistry 2009年第11期52卷 1808-1813页

作者： CHEN FangFang,JIANG WeiLi,LOU Bin,BIAN ZuQiang & HUANG ChunHui beijing National Laboratory for Molecular Sciences,State Key Laboratory of Rare Earth Materials chemistry and Applications,College of chemistry and Molecular engineering,peking university,beijing 100871,china beijing National Laboratory for Molecular Sciences State Key Laboratory of Rare Earth Materials Chemistry and Applications College of Chemistry and Molecular Engineering Peking University Beijing China

Bipyrimidines have been chosen as(N^N)(N^N) bridging ligands for connecting metal ***Ⅲ-LnⅢ(Ln = Nd,Yb,Er) bimetallic complexes [Ir(dfppy)2.μ-bpm)Ln(TTA)3]Cl were synthesized by using Ir(dfppy)2.bpm)Cl as the ligand coordinating to lanthanide complexes Ln(TTA)3·*** stability constants between Ir(dfppy)2.bpm)Cl and lanthanide ions were measured by fluorescence *** obvious quenching of visible emission from IrⅢ complex in the IrⅢ-LnⅢ(Ln = Nd,Yb,Er) bimetallic complexes indicates that energy transfer occurred from IrⅢ center to *** emissions from NdⅢ,YbⅢ,and ErⅢ were obtained under the excitation of visible light by selective excitation of the IrⅢ-based *** was proven that Ir(dfppy)2.bpm)Cl as the ligand could effectively sensitize NIR emission from NdⅢ,YbⅢ,and ErⅢ.

关键词： bipyrimidine IrⅢ-LnⅢ bimetallic complexes stability constant NIR emission excitation of visible light

SYNTHESIS OF MESOPOROUS POLY(STYRENE-co-MALEIC ANHYDRIDE)/SILICA HYBRID MATERIALS VIA A NONSURFACTANT-TEMPLATED SOL-GEL PROCESS

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 469-472页

作者： Jie-bin Pang Kun-yuan Qiu Yen Wei Department of Polymer Science and engineering, College of chemistry and Molecular engineering, peking university, beijing 100871, china. Department of chemistry, Drexel university, Philadelphia, Pennsylvania 19104, USA. peking Univ Coll Chem & Mol Engn Dept Polymer Sci & Engn Beijing 100871 Peoples R China Drexel Univ Dept Chem Philadelphia PA 19104 USA

Mesoporous poly(styrene-co-maleic anhydride)/silica hybrid materials have been prepared. The synthesis was achieved by the HCl-catalyzed sol-gel reactions of tetraethyl orthosilicate (TEOS) and styrene-maleic anhydride copolymer in the presence of 3-aminopropyl triethoxysilane (APTES) as a coupling agent and citric acid as a nonsurfactant template or pore-forming agent, followed by ethanol extraction. Characterization results from nitrogen sorption isotherms and powder X-ray diffraction indicate that polymer-modified mesoporous materials with large specific surface areas (e.g. 900 m(2./g) and pore volumes (e.g. 0.6 cm(3)/g) could be prepared. As the citric acid concentration is increased, the specific surface areas, pore volumes and pore diameters of the hybrid materials increase.

关键词： mesoporous hybrid material poly(styrene-co-maleic anhydride)/silica citric acid nonsurfactant template sol-gel process

Petrogenesis of Songshugou dunite body in the Qinling orogenic belt, Central china: Constraints from geochemistry and melt inclusions

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2005年第8期48卷 1146-1157页

作者： SU Li1,2. SONG Shuguang3 & ZHOU Dingwu1 1. Key Laboratory of Continental Dynamics of the Ministry of Education, Department of Geology, Northwestern university, Xi’an 710069, china 2. The Geological Lab {2., china university of Geosciences (beijing), beijing 100083, china 3. Key Laboratory of Orogenic Belts of the Ministry of Education, Department of Geology, peking university, beijing 100871, china 1. Key Laboratory of Continental Dynamics of the Ministry of Education Department of Geology Northwestern University 710069 Xi’an China 2. The Geological Lab center China University of Geosciences 100083 (Beijing)Beijing China 3. Key Laboratory of Orogenic Belts of the Ministry of Education Department of Geology Peking University 100871 Beijing China

The Songshugou dunite body, which occupies an area of about 2. km2. is the largest ultramafic massif in the eastern Qinling orogenic belt, Central china. The major compo-nent of this body is dunitic rocks including mylonitic dunite and coarse-grained dunite; they oc-cupy about 95 vol% of the total body. Petrography, mineral composition, major and trace ele-ments and primitive melt inclusions have been investigated in this paper; all revealed that this dunite body is the product of melt-rock interaction by porous percolation flow. In comparison with dunite sills or veins in harzburgite from the basal part of Oman ophiolite, this dunite body is characterized by lower contents of Al2.3, CaO and HREE but higher content of highly incom-patible elements and Zr and Hf. The LREE enriched patterns and primitive mantle normalized spidergrams of trace elements are also different from the Oman dunite. Combining with melt in-clusions observed in olivines, we conclude that this dunite body is the product of large- scale porous percolation flow of high-MgO melts within depleted mantle peridotites. The high-MgO magma, in essence, was most probably produced at the hot head of an upwelling mantle plume. The occurrence of the Songshugou dunite body is closely associated with the activity of mantle super-plume in Neo-Proterozoic era in the Yangtze Craton.

关键词： Songshugou dunite body, geochemistry, melt inclusion, mantle plume, Qinling orogenic belt.

SYNTHESIS AND CHARACTERIZATION OF STRUCTURALLY WELL-DEFINED POLYMER-INORGANIC HYBRID NANOPARTICLES VIA ATRP

在线全文

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 261-267页

作者： Jie Bai Jie-bin Pang Kun-yuan Qiu Yen Wei Department of Polymer Science & engineering College of chemistry & Molecular engineering peking university beijing 100871, china Department of chemistry Drexel university Philadelphia, PA 19104 USA peking Univ Coll Chem & Mol Engn Dept Polymer Sci & Engn Beijing 100871 Peoples R China Drexel Univ Dept Chem Philadelphia PA 19104 USA

Atom transfer radical polymerization (ATRP) using cuprous chloride/2.2.-bipyridine (bipy) was applied to graft polymerization of styrene on the surface of silica nanoparticles to synthesize polymer-inorganic hybrid nanoparticles, 2.(4Chloromethylphenyl) ethyltriethoxysilane (CTES) was immobilized on the surface of silica nanoparticles through condensation reaction of the silanol groups on silica with triethoxysilane group of CTES. Then ATRP of St was initiated by this surface-modified silica nanoparticles bearing benzyl chloride groups, and formed PSt graft chains on the surface of silica nanoparticles. The thickness of the graft chains increased with reaction time. End group analysis confirmed the occurrence of ATRP. Thermal analysis indicated that thermal stabilization of these resulting hybrid nanoparticles also increases with polymerization conversion. The results above show that this 'grafting from' reaction could be used for the preparation of polymer-inorganic hybrid nanoparticles with controlled structure of the polymer's end groups.

关键词： atom transfer radical polymerization polymer-inorganic hybrid nanoparticles 2.(4-chloromethylphenyl)ethyltriethoxysilane surface-modification

Mass spectrometric identification of double bond positional isomers of hexadecenyl acetate without chemical derivatization

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of chemistry 1994年第4期12卷 348-354页

作者： YUAN, GuDepartment of chemistry, peking university, {2., chinaHORIIKE, Michio KIM, Chul-Sa HIRANO, Chisato Department of Agricultural chemistry, Kochi university, Nankoku-shi, Kochi 783, Japan 1Department of chemistry Peking University Beijing 100871 China2Department of Agricultural Chemistry Kochi University Nankoku-shi Kochi 783 Japan

A method for the identification of the double bond positional isomers of hexadecenyl acetate has been established by analysing similarity of the mass spectra patterns on a fuzzy classification, in which the intensity ratios of six diagnostic pairs of the predominant ions were selected as standard parameters for the characterization of the double bond position. The procedure was tested with △2.to △15-isomers of chemically unmodified hexadecenyl acetate, and the original double bond position in the acetates was located unambiguously.

关键词： Mass spectrometer double bond positional isomers hexadecenyl acetates.

SYNTHESIS OF HYBRID MESOPOROUS POLYSTYRENE-SILICA MATERIALS WITH NON-SURFACTANT CITRIC ACID AS TEMPLATE VIA SOL-GEL PROCESS

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2002年第6期20卷 565-572页

作者： Jie Bai Jin-yu Zheng Kun-yuan Qiu Yen Wei Department of Polymer Science & engineering College of chemistry & Molecular engineering, peking university beijing 100871, china Department of chemistry, Drexel university, Philadelphia, PA 19104, USA peking Univ Coll Chem & Mol Engn Dept Polymer Sci & Engn Beijing 100871 Peoples R China Drexel Univ Dept Chem Philadelphia PA 19104 USA

Hybrid mesoporous polystyrene-silica materials were successfully prepared through HCl-catalyzed sol-gel reactions of tetraethyl orthosilicate (TEOS) and triethoxysilyl-functionalized polystyrene obtained via atom transfer radical polymerization (ATRP) of styrene, in the presence of citric acid (CA) as non-surfactant template or pore-forming agent and followed by ethanol extraction to remove template molecules. The materials were characterized by infrared spectroscopy OR), N-2.adsorption-desorption measurements, powder X-ray diffraction (XRD), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM). The results indicate that the materials prepared with 50 wt%-60 wt% template contents have average pore sizes of 2.3 nm and large surface areas (ca. 886 m(2./g) as well as high pore volumes (ca. 0.53 cm(3)/g). The mesoporosity arises from interconnected channels and pores with disordered arrangements. The pore diameters and pore volumes increase as the template content is increased. The pore diameters show a little change upon heating at 2.0degreesC overnight. However, the materials do not have good hydrothermal stability.

关键词： atom transfer radical polymerization hybrid material mesoporous polystyrene silica

Approach to synthesis of novel chiral 3-chloro-2.5H)- furanone and its application in asymmetric reactions

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2000年第8期45卷 711-716页

作者： HUANG Hui & CHEN Qinghua1. Department of chemistry, Tonghua Teacher’s College, Tonghua 134002. china 2. Department of chemistry, beijing Normal university, beijing 100875, china Department of chemistry Tonghua Teacher’s College Tonghua China Department of chemistry Beijing Normal University Beijing China

The synthetic method of the novel chiral synthon, 5-/-menthyloxy-3-chloro-2.(5H)-furanone 5a and its application in asymmetric reactions were investigated. 5a is easily obtained in highly optical purity, and acts as a stable acceptor of Michael addition with oxygen nucleophiles in tandem double Michael addition / internal nucieophilic substitution to offer the spiro-cyclopropane derivative containing four stereogenic centers 8, which it is difficult to obtain by routine methods. The synthetic methods for 5a and 8 are reported in detail and the new compounds are identified on the basis of their analytical data and spectroscopic data, such as UV, IR, H NMR,13 C NMR, MS and elementary analysis. The absolute configuration of the interesting spiro-cyclopropanes, spiro [1-chloro-4-(/-menthyloxy)-5-oxo-6-oxa-biscyclo[3.1.0]hexane-2.3i(4’-/-menthyloxy-5’-/-menthyloxy- butyrolactone)] 8 was established by X-ray crystallography. This result can provide important synthetic strategy in synthesis of some complex

关键词： new chiral synthon. 5-l-menthyloxy-3-chloro-2.(5H)-furanone absolute configuration spiro-cyclopropane derivative containing multiple chiral centers.

Theoretical study on thermal decomposition of azoisobutyronitrile in ground state

在线全文

学校读者我要写书评

暂无评论

Science china chemistry 2004年第5期47卷 373-380页

作者： SUN Chengke1,2. ZHAO Hongmei1 & LI Zonghe1 1. Department of chemistry, beijing Normal {2., beijing 100875, china 2. Department of chemistry, Qujing Normal College, Qujing 655000, china 1. Department of chemistry Beijing Normal University 100875 Beijing China 2. Department of chemistry Qujing Normal College 655000 Qujing China

The thermal decomposition mechanisms of azoisobutyronitrile (AIBN) in the ground state have been investigated systematically. Based on the potential energy surfaces (PES) of various possible dissociation paths obtained using the semiempirical AM1 method with partial optimization, the density function theory B3LYP/6-311G* method was employed to optimize the geometric parameters of the reactants, the intermediates, the products and the transition states, which were further confirmed by the vibrational analysis. The obtained results show that the re- action process of the two-bond (three-body) simultaneous cleavage Me2.CN)C─ N=N─ C(CN)Me2. 2.e2.CN)C?+N2.is much more favorable than the reaction process of the two one- bond asynchronous cleavage Me2.CN)CN=N─C(CN)Me2.? Me2.CN)CN=N?+ Me2.CN)C?? Me2.CN)C?+ N2. It was suggested that the electron shrinking effect of double bond (─N=N─) in AIBN and the stabilities of the Me2.CN)C?radical as well as N2.molecule are main factors of leading to the reaction proceeding in the former pathway. The calculation results were consistent with all the experimental facts.

关键词： azoisobutyronitrile, radicals, thermal decomposition, density function theory (DFT).

Environmental regulatory and policy framework in china: an overview

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2001年第1期13卷 122-128页

作者： ZHANG Shi qiu (center for Environmental Sciences, peking university, {2., china. E mail: zhangshq@***) center for Environmental Sciences Peking University Beijing 100871 China. zhangshq@***

china has developed one of the most comprehensive environmental regulatory and policy framework in the world. This paper provides a description of the main institutions for environmental management in china, and overv... 详细信息

关键词： Laws and legislation Public policy Regulatory compliance Societies and institutions

The Electrochemical Impedance Behavior of the Living Cells Escherichia Coli

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 1997年第12期8卷 0-0页

作者： Wei LI Jun FENG Hua Quan YANG and Yun Xiang CI(Department of chemistry, peking university, {2.) peking Univ Dept Chem Beijing 100871 Peoples R China

The semiconductive characteristics of clectron-transfrring proteins in living cells E coli was investigated by electrochemsical impedance spectroscopy(EIS). We found that the electrochemical impedance of living cells as a function of temprature followed the Arrhenius equation for semiconductors. This result shows a strong evidence to prove the semiconductive behavior of proteins

关键词： The Electrochemical Impedance Behavior of the Living Cells Escherichia Coli