检索结果-南通市图书馆

Science china chemistry 2008年第2期51卷 120-127页

作者： WEI RuiPing1,2, GU YanBo1 & WANG Jun1 1 State Key Laboratory of Materials-Oriented chemical engineering, college of chemistry and chemical engineering, nanjing Uni- versity of Technology, nanjing 210009, china 2 college of chemistry and chemical engineering, southeast university, nanjing 211189, china State Key Laboratory of Materials-Oriented chemical engineering College of Chemistry and Chemical Engineering Nanjing University of Technology Nanjing China college of chemistry and chemical engineering Southeast University Nanjing China

The bimetal-bearing (CePt or LaPt) 12-tungstophosphoric acid (H3PW12O40 (PW)) catalysts supported on dealuminated USY zeolite (DUSY) were prepared by impregnation and characterized by XRD, BET, IR, and H2-chemisorption. Their catalytic activities were tested in the hydroisomerization of n-heptane with a continuous atmospheric fixed-bed reactor. After the steam treatment combined with the acid leaching, as well as the supporting with PW and the bimetals, the DUSY support retains the Y zeolite porosity and the PW well keeps its Keggin structure in catalysts. The doping of Ce into the catalysts enhances the dispersion of Pt on the catalyst surface. The Pt-bearing PW catalysts doped with Ce or La, especially Ce, exhibit much higher catalytic activity and selectivity than the catalysts without dopants at lowered reaction temperatures. At the optimal reaction conditions, i.e., the reaction temperature of 250℃ and WHSV of 1.4 h1, the catalyst with a Pt loading of 0.4%, PW loading of 10% and a molar ratio of Ce to Pt of 15:1 shows a conversion of n-heptane of 70.3% with a high selectivity for isomerization products of 94.1%.

关键词： hydroisomerization of n-heptane bimetal catalyst heteropoly acid USY platinum

A NOVEL INTERPRETATION OF CONCENTRATION DEPENDENCE OF VISCOSITY OF DILUTE POLYMER SOLUTION

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1期18卷 57-67页

作者： Yan Pan Rong-shi Cheng college of Material Science and engineering, South china university of Technology, Guangzhou 510641, china college of chemistry and chemical engineering, nanjing university, nanjing 210093, china 华南理工大学广东广州

The concentration dependence of the reduced viscosity of dilute polymer solution is interpreted in the light of a new concept of the self-association of polymer chains in dilute solution. The apparent self-association constant is defined as the molar association constant divided by the molar mass of individual polymer chain and is numerically interconvertible with the Huggins coefficient. The molar association constant is directly proportional to the effective hydrodynamic volume of the polymer chain in solution and is irrespective of the chain architecture. The effective hydrodynamic volume accounts for the non-spherical conformation of a short polymer chain in solution and is a product of a shape factor and hydrodynamic volume. The observed enhancement of Huggins coefficient for short chain and branched polymer is satisfactorily interpreted by the concept of self-association. The concept of self-association allows us to predict the existence of a boundary concentration C-s(dynamic contact concentration) which divides the dilute polymer solution into two regions.

关键词： self-association polymer solution viscosity concentration dependence

Propane Dehydrogenation over PtSnNa Catalyst Supported on La-ZSM-5 Zeolite

在线全文

学校读者我要写书评

暂无评论

china Petroleum Processing & Petrochemical Technology 2010年第3期12卷 18-24页

作者： Huang Li Zhou Yuming Zhang Yiwei Li Qingning Tian Xiaoming (School of chemistry and chemical engineering,southeast university,nanjing 211189) School of chemistry and chemical engineering Southeast University Nanjing 211189 China

The La-ZSM-5 zeolite with different contents of La was synthesized by the hydrothermal method. The physico-chemical properties of the materials were studied. The results of FT-IR analyses indicated that La might be incorporated into the framework of ZSM-5 zeolite. The NH3-TPD analyses showed that the amount of weak acid sites of the zeolite decreased with a continuously increasing La content. Afterwards, the La-ZSM-5 zeolite was used as the support of PtSnNa catalyst for propane dehydrogenation. The test results revealed that the utilization of La- ZSM-5 zeolite could achieve a high propene conversion, and effectively inhibit the coke formation on the catalyst surface. When the content of La was 0.16%, the catalytic activity and stability of the catalyst got the best of its performance. Besides, the PtSnNa/La （0.16%）-ZSM-5 catalyst is more stable than the conventional PtSnNaLal ZSM-5 catalysts.

关键词： La-ZSM-5 propane dehydrogenation propene.

Cross-linked Polyethylenimine as Potential DNA Vector for Gene Delivery with High Efficiency and Low Cytotoxicity

在线全文

学校读者我要写书评

暂无评论

Acta Biochimica et Biophysica Sinica 2006年第11期38卷 780-787页

作者： Wei DONG~(1,2) Guang-Hui JIN~1 Shu-Feng LI~(1,3) Qi-Ming SUN~1 Ding-Yuan MA~1 Zi-Chun HUA~1 1 State Key Laboratory of Pharmaceutical Biotechnology,college of Life Science,nanjing university,nanjing 210093,china 2 School of chemical engineering nanjing university of Science and Technology,nanjing 210094,china 3 college of Basic Medical Science,southeast university,nanjing 210009,china State Key Laboratory of Pharmaceutical Biotechnology College of Life Science Nanjing UniversityNanjing 210093 China School of chemical engineering Nanjing University of Science and TechnologyNanjing 210094 China college of Basic Medical Science Southeast UniversityNanjing 210009 China

Polyethylenimine (PEI) has been known as an efficient gene carrier with the highest cationiccharge *** transfection efficiency of PEI,along with its cytotoxicity,strongly depends on itsmolecular *** enhance its gene delivery efficiency and minimize cytotoxicity,we have synthesizedsmall cross-linked PEI with biodegradable linkages and evaluated their transfection efficiencies in *** study,branched PEI with a molecular weight of 800 Da was cross-linked by small diacrylate[1,4-butanediol diacrylate or ethyleneglycol dimethacrylate (EGDMA)] for 2-6 *** efficiencies of thecross-linked PEI in in vitro transfection of plasmid DNA containing enhanced green fluorescent protein(EGFP) reporter gene were assessed in melanoma B 16F10 cell line and other cell *** cytometrywas used to quantify the cellular entry efficiency of plasmid and the transgene expression *** of the cross-linked PEI in these cells were evaluated by MTT ***-PEI 800-4h,atypical cross-linked PEI reported here,mediated a more efficient expression of reporter gene than thecommercially available 25-kDa branched PEI control,and resulted in a 9-fold increase in gene deliveryin B16F10 cells and a 16-fold increase in 293T cells,while no cytotoxicity was found at the optimizedcondition for gene ***,the transfection activity of polyplexes was preserved in thepresence of serum proteins.

关键词： polyethylenimine gene delivery cytotoxicity B16F10 293T cell line

Mesoporous Si-MCM-48 membrane prepared by pore-filling method

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(Technological Sciences) 2010年第4期53卷 1064-1068页

作者： XU DeKan & FAN YiQun State Key Laboratory of Materials-Oriented chemical engineering,college of chemistry and chemical engineering,nanjing university of Technology,nanjing 210009,china State Key Laboratory of Materials-Oriented chemical engineering College of Chemistry and Chemical Engineering Nanjing University of Technology Nanjing China

Mesoporous MCM-48 membranes were prepared on asymmetric zirconia tubular support with an average pore size of 0.2 μm by hydrothermal *** support should be pretreated with H2O as a pore-filling substance to prevent the sol solution from infiltrating into the support *** SEM showed that the MCM-48 membrane was composed of tightly-connected spherical *** single gas N2 and H2 permeation experiments confirm that crack-free membrane could be prepared by pore-filling method.N2 permeance of MCM-48 membrane,synthesized by secondary growth,can reach 5.66×10-7 mol/Pa·s·m2,and the H2/N2 separation factor was 3.47 under trans-membrane pressure of 0.05 MPa.

关键词： MCM-48 mesoporous membrane pore-filling

Effect of Ga Addition on Catalytic Performance of PtSnNa/ZSM-5 Catalyst for Propane Dehydrogenation

在线全文

学校读者我要写书评

暂无评论

china Petroleum Processing & Petrochemical Technology 2011年第4期13卷 45-52页

作者： Liu Xuan Zhou Yuming Zhang Yiwei Duan Yongzheng Xue Mengwei Wan Lihui (School of chemistry and chemical engineering, southeast university, nanjing 211189) School of chemistry and chemical engineering Southeast University Nanjing 211189 China

PtSnNaGa/ZSM-5 catalysts with different contents of Ga were prepared and characterized by X-ray diffraction (XRD), nitrogen adsorption, hydrogen chemisorption, ammonia temperature-programmed desorption (NH3-TPD), hydrogen temperature-programmed reduction (H2-TPR), and temperature-programmed oxidation (TPO) techniques. The performances of these catalysts for propane dehydrogenation were investigated. The test results indicated that the addition of Ga not only could improve the catalytic stability and propene selectivity, but also could effectively prevent the catalysts from coking. It was found that the PtSnNaGa(0.5 m%)/ZSM-5 catalyst exhibited the best performance in terms of propene selectivity and propane conversion. The high catalytic performance was most probably attributed to the presence of Ga that could strength- en the interaction between metals and the support to stabilize the catalytic active sites.

关键词： gallium platinum ZSM-5 propane dehydrogenation catalyst

Polymer-assisted nanoparticulate contrast-enhancing materials

在线全文

学校读者我要写书评

暂无评论

Science china chemistry 2010年第3期53卷 479-486页

作者： DING Yin1,3,HU Yong2,WU Wei1 & JIANG XiQun1 1Laboratory of Mesoscopic chemistry and Department of Polymer Science and engineering,college of chemistry & chemical engineering,nanjing university,nanjing 210093,china 2National Laboratory of Solid State Microstructure,Department of Material Science and engineering,nanjing university,nanjing 210093,china 3Key Laboratory of Analytical chemistry for Life Science,Ministry of Education,School of chemistry and chemical engineering,nanjing university,nanjing 210093,china Laboratory of Mesoscopic chemistry and Department of Polymer Science and engineering College of Chemistry & Chemical Engineering Nanjing University Nanjing China Key Laboratory of Analytical chemistry for Life Science Ministry of Education School of Chemistry and Chemical Engineering Nanjing University Nanjing China National Laboratory of Solid State Microstructure Department of Material Science and Engineering Nanjing University Nanjing China

The application of nanotechnology in medicine research has significant potential in modern biomedical research,disease diagnosis and *** fluorophore-based detection techniques have been widely used as imaging and signal transduction tools for the detection of trace levels of *** photosensitivity of the fluorophores,however,limits their application in such complex environments as living bio-systems where degradation or photobleaching *** nanoparticles have unique and stable optical,electrical,magnetic and catalytic properties because of their various shapes,sizes and *** potential of the nanoparticles as novel imaging agents has been studied as a possible solution to this *** modification of inorganic nanoparticles could enhance their biostability in physiological conditions and ability of targeting bioactive molecules.

关键词： contrast agent cell image gold nanoparticles iron oxide nanoparticles carbon nanotubes polymeric-inorganic hybrid nanoparticles

A study on methane coupling to acetylene under the microwave plasma

在线全文

学校读者我要写书评

暂无评论

Science china chemistry 2010年第1期53卷 231-237页

作者： SHEN ChangSheng1,SUN YongZhi1,SUN DeKun2 & YANG HongSheng1 1State Key Laboratory of Millimeter Waves School of Electronic Science and engineering,southeast university,nanjing 210096,china 2School of chemistry and chemical engineering,nanjing university,nanjing 210093,china State Key Laboratory of Millimeter Waves School of Electronic Science and engineering Southeast University Nanjing China School of chemistry and chemical engineering Nanjing University Nanjing China

By optimizing the microwave chemistry reactor made of the rectangular waveguide resonator,the methane conversion(the maximum 93.7%),the C2 hydrocarbon yield(the maximum 91.0%) and the acetylene yield(the maximum 88.6%) were all greatly increased under the microwave ***,for the optimal reactor,the change of the methane conversion and the C2 hydrocarbon yield is little within the range of the pressures in the *** C2 hydrocarbon is mainly made up of acetylene,and the selectivity for acetylene is above 90%.Energy yield and space time yield of acetylene are also *** emission spectroscopy(OES) was adopted for the diagnosis of methane coupling to acetylene under microwave *** excited species(CH,C2,H2,Hα) were detected in the spectra range of 300-750 *** on the products and the excited species,the reaction mechanism of methane coupling under microwave plasma was investigated,using the thermodynamics and kinetics of the chemical reaction.

关键词： microwave plasma methane acetylene

Regioselective aminohalogenation of β-nitrostyrenes using NCS and NBS as nitrogen/halogen sources

在线全文

学校读者我要写书评

暂无评论

Science china chemistry 2010年第1期53卷 140-146页

作者： ZHI SanJun1,2,SUN Hao2,LIN Chen2,ZHANG GuangQian2,LI GuiGen4 & PAN Yi2,3 1 Department of chemistry,Huaiyin Normal university,Huai’an 221003,china 2 School of chemistry and chemical engineering,nanjing university,nanjing 210093,china 3 State Key Lab of Coordination chemistry,nanjing university,nanjing 210093,china 4 Department of chemistry and Biochemistry,Texas Tech university,Lubbock,Texas 79409-1061,USA Department of chemistry Huaiyin Normal University Huai’an China School of chemistry and chemical engineering Nanjing University Nanjing China Department of chemistry and Biochemistry Texas Tech University Lubbock USA State Key Lab of Coordination chemistry Nanjing University Nanjing China

Aminohalogenation reaction of β-nitrostyrenes with N-halosuccinimides(N-chloro and N-bromosuccinimides) has been successfully conducted by using nickel acetate as a catalyst in the presence of potassium carbonate and succinimide as *** reaction was easily performed at room temperature under nitrogen gas protection to give dihalorinaed haloamino products in good to excellent yields(60%-98%).The structure has been confirmed by X-ray crystal structure analysis.

关键词： aminohalogenation vicinal haloamines β-nitrostyrenes NBS NCS

Cycloaddition mechanism for the resin-OsO_4-catalyzed of styrene: A DFT study

在线全文

学校读者我要写书评

暂无评论

Science china chemistry 2008年第1期51卷 19-24页

作者： ZHANG XingHui1, WANG KeTai1 & FANG Ran2 1 college of chemical engineering, Gansu Unite university, Lanzhou 730000, china 2 college of chemistry and chemical engineering, Sun Yat-sen university, Guangzhou 510275, china college of chemical engineering Gansu Unite University Lanzhou China college of chemistry and chemical engineering Sun Yat-sen University Guangzhou China

The postulated intermediates in the base-free and base-assisted addition of OsO4 to styrene have been investigated at the B3LYP/6-311G** level of the theory. N(CH3)2(Ph) was chosen as the base of the resin-OsO4. According to our model calculations the [2+3] addition was found to be favorable with an activation of 2+2] cycloaddition remain high (>155.00 kJ/mol). In addition, the electronic structure analysis of the molecules was carried out by na- ture bond orbital (NBO). The computational results were in reasonable agreement with experimental results.

关键词： cycloaddition resin-OsO4 density functional theory