检索结果-南通市图书馆

chinese Journal of chemistry 1997年第5期15卷 395-404页

作者： zhang, yu-huang jiang, bin jiang, xi-kuishanghai institute of organic chemistry, chinese academy of sciences, shanghai 200032, china shanghai institute of organic chemistry Chinese Academy of Sciences Shanghai 200032 China

The fluorescence quenching coefficient (Ksv) and the quenching rate constant kq of ten para-substituted styrenes (1-Ys) have been measured and correlation-analyzed by both the dual-parameter equation (Eq. 1) with (ρxσx+ρ'σ') and the single-parameter equation (Eq. 2) with ρxσx. Ex-cellent results have been obtained for the correlation of KSV against (ρxσmb+ρ'σ'JJ) or (ρxσ+ +ρ'σ'JJ). Our results suggest that, possibly, there might be no need to use excited-state substituent constant for the fluorecence quenching process of excited states of styrenes.

关键词： Fluorescence quenching correlation analysis styrenes dual-parameter equation

Substituent effects on the EPR aN values of symmetrically para-disubstituted diphenyl nitroxides

在线全文

学校读者我要写书评

暂无评论

chinese Journal of chemistry 1994年第6期12卷 516-523页

作者： zhang, yu-huang jiang, bin ZHOU, Cheng-Ming jiang, xi-kuishanghai institute of organic chemistry, chinese academy of sciences, 354 Fenglin Lu, shanghai 200032, china shanghai institute of organic chemistry Chinese Academy of Sciences 354 Fenglin Lu Shanghai 200032 China

Nitrogen hyperfine splitting constants (aN values) of seven symmetrically para-disubstituted diphenyl nitroxides (1-Y's) were measured by EPR and used in conjunction with five literature values in our correlation analysis. The correlation of these ON values by single-parameter Eq. 1 and dual-parameter Eq. 2 shows that the application of Eq. 2 does not significantly improve the correlation. But our data can also be interpreted by the proposition that the spin-delocalization effect is not completely nonexistent and that it might have revealed itself through the aN values of two very weakly polar substituents with pronounced spin-stabilizing abilities, i.e., SMe and SiMe3.

关键词： EPR diphenyl nitroxides correlation analysis dual-parameter equation.

Fluorescence study on the coaggregating tendencies of the cholesterols --the culprits of arteriosclerosis

在线全文

学校读者我要写书评

暂无评论

chinese Journal of chemistry 1994年第3期12卷 277-282页

作者： zhang, Jin-Tao JI, Guo-Zhen jiang, xi-kuishanghai institute of organic chemistry, chinese academy of sciences, 354 Fenglin Lu, shanghai 200032, china shanghai institute of organic chemistry Chinese Academy of Sciences 354 Fenglin Lu Shanghai 200032 China

The coaggregating tendencies of the culprits of arteriosclerosis, the cholesteryl esters (CE-n's), have been investigated in the 40:60 V/V (Φ= 0.40) dioxane (DX)-H2O system, by using decyl pyrenyl ketone (Py-11) as the fluorescence probe. The fluorescence intensity of Py-11 decreases when coaggregation occurs between CE-n and Py-11, because of the low polarity of the microenviroment of the coaggregates. The order of the coaggregating tendencies obtained from the fluorescence data is in full agreement with that from the kinetic method, i.e., CE-ol, CE-in > CE-12 > CE-8 > CE-18 > CE-0.

关键词： Cholesteryl esters fluorescence probe coaggregating tendency.

SYNTHESIS AND CHARACTERIZATION OF A NOVEL FLUORINE-CONTAINING HYDROPHOBICALLY ASSOCIATING POLYMER

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 281-288页

作者： Jin Yang Wei-yuan huang Laboratory of Organofluorine chemistry, shanghai institute of organic chemistry, chinese academy of sciences, shanghai 200032, china 中科院上海有机化学所上海 200032 中科院上海有机化学所上海

In this article, the synthesis and characterization of a novel fluoromonomer and its copolymer with acrylamide is reported. 2-perfluoroamyl-4-hydroxylquinoline 2 was synthesized from ethyl 2, 2-dihydroperfluoroheptanoate in high yields. The monomer 4 was then synthesized from 2 in two steps readily in high yields. Synthesis and characterization of copolymers of acrylamide (AM) and the fluoromonomer were investigated. The composition and intrinsic viscosity of these copolymers were studied. It was found that the rheological properties of aqueous solutions of polyacrylamide were modified significantly when a small proportion of the fluoromonomer 4 was incorporated on investigating the viscosity-concentration profiles, pseudoplasticity of these solutions and the effect of the presence of surfactant. These results could be explained by the hydrophobic association of the fluorocarbon segments in the aqueous solutions of these copolymers.

关键词： hydrophobically associating polymer fluorine-containing acrylate perfluoroalkylation with RFI/Na2S2O4

Temperature effect on the ease of aggregation

在线全文

学校读者我要写书评

暂无评论

chinese Journal of chemistry 1994年第2期12卷 179-182页

作者： zhang, Jin-Tao NIE, Jin SUN, Si-Xun JI, Guo-Zhen jiang, xi-kuishanghai institute of organic chemistry, chinese academy of sciences, 354 Fenglin Lu, shanghai 200032, china shanghai institute of organic chemistry Chinese Academy of Sciences 354 Fenglin Lu Shanghai 200032 China

The effect of temperature on the critical aggregate concentration (CAgC) has been investigated for the first time, by measurement of the hydrolytic rate constants of p-nitrophenyl dodecanoate (C12) and hexadecanoate (C16) at different temperatures in the 30:70 V/V (Φ=0.30) and 40:60 V/V (Φ= 0.40) dioxane (DX)-H2O systems. The CAgC values of C12 and C16 increase with the increase of the temperature, i.e., high temperatures disfavor aggregation. Activation energies for the hydrolysis of C12 in the monomeric and aggregated concentration domains have also been discussed.

关键词： Temperature activation energy CAgC Cn aggregation.

Perfluoroalkylation of benzo crown ethers with sodium perfluoroalkanesulfinates in the presence of oxidant

在线全文

学校读者我要写书评

暂无评论

chinese Journal of chemistry 1994年第3期12卷 283-288页

作者： huang, Wei-yuan LIU, Jin-Taoshanghai institute of organic chemistry, chinese academy of sciences, 354 Fenglin Lu, shanghai 200032, china shanghai institute of organic chemistry Chinese Academy of Sciences 354 Fenglin Lu Shanghai 200032 China

Using Ce(SO4)2 or Mn(OAc)3 as oxidant, dibenzo crown ethers such as dibenzo-18-crown-6 (1) and dibenzo-24-crown-8 (5) and benzo-12-crown-4 (7) reacted smoothly with sodium perfluoroalkanesulfinates (2a-2e) to give the corresponding perfluoroalkylated products (3,4,6,7) in good yields with two isomers obtained in the case of dibenzo crown ethers. This provides a facile synthesis of perfluoroalkyl-containing crown ethers.

关键词： Perfluoroalkylation perfluoroalkyl benzo crown ether sodium perfluoroalkanesulfinate.

Study on the sulfinatodehalogenation of BrCF_2CF_2R

在线全文

学校读者我要写书评

暂无评论

chinese Journal of chemistry 1997年第5期15卷 472-474页

作者： HU, Qiao-Sheng HU, Chang-Ming huang, Wei-yuanshanghai institute of organic chemistry, chinese academy of sciences, shanghai 200032, china shanghai institute of organic chemistry Chinese Academy of Sciences Shanghai 200032 China

Sodium dithionite initiated sulfinatodehalogenation of BrCF2CF2R is studied.

关键词： Sulfinatodehalogenation fluorinated alkyl bromide fluorinated sulfinates fluorinated sultene

The spin delocalization substituent parameter σ——8. The spin-delocalizing abilities of the nitro, cyano, carbomethoxy, carboxy and carbamyl groups

在线全文

学校读者我要写书评

暂无评论

chinese Journal of chemistry 1991年第6期9卷 521-526页

作者： JI, Guo-Zhen jiang, xi-Kui SHI, Wen-Ting. shanghai institute of organic chemistry, The chinese academy of sciences, shanghai 200032 shanghai institute of organic chemistry The Chinese Academy of Sciences Shanghai 200032

The rate constants (k) of the homo-cycloaddition reactions of five substituted α, β, β-tri- fluorostyrenes (TFS’s), i.e. p-nitrotrifluorostyrene (4), p-cyanotrifluorostyrene (5), p-carbomethoxytri- fluorostyrene (6), p-carboxytrifluorostyrene (7) and p-carbamyltrifluorostyrene (8), have been measured in the temperature range of 110-160℃. The ~σmb polar substituent parameters of these TFS's cal- culated from ^(19) F NMR chemical shifts are: NO_2, 0.86; CN, 0.86; CO_2CH_2, 0.40; CO_2H, 0.31; CONH_2, 0.10. The spin delocalization substituent parameters ~σT of NO_2, CN, CO_2 CH_2, CO_2H and CONH_2 are 0.32, 0.38, 0.31, 0.37 and 0.37 respectively. Thus all these electron-pair attracting groups are also very effective spin-stabilizers.

关键词： The spin delocalization substituent parameter carboxy and carbamyl groups cyano

Synthesis of perfluoroalkyl-containing steroidal glycosides

在线全文

学校读者我要写书评

暂无评论

chinese Journal of chemistry 1992年第3期10卷 262-267页

作者： huang, Wei-yuan L(?), Long shanghai institute of organic chemistry, chinese academy of sciences, shanghai 200032 shanghai institute of organic chemistry Chinese Academy of Sciences Shanghai 200032

A new kind of fluorine-containing amphiphiles -- perfluoroalkyl-containing steroidal glycos- ides were synthesized in good yield through perfluoroalkylation by means of sodium dithionite-initiated addition of R_FI to olefinic system. Preliminary study showed that these glycosides could form vesicles in aqueous medium as observed by electron microscopy.

关键词： Am Synthesis of perfluoroalkyl-containing steroidal glycosides

Establishing Modular Cell-Free Expression System for the Biosynthesis of Bicyclomycin from a Chemically Synthesized Cyclodipeptide

在线全文

学校读者我要写书评

暂无评论

chinese Journal of chemistry 2024年第4期42卷 384-390页

作者： Yi-Pei Liu yu-Heng Zhao Wen-Qi zhang Lian Wu Linjuan huang Gong-Li Tang Jun-bin He Shaanxi Natural Carbohydrate Resource Engineering Research Center College of Food Science and TechnologyNorthwest UniversityXi'anShaanxi710069 China State Key Laboratory of Chemical Biology Shanghai Institute of Organic ChemistryUniversity of Chinese Academy of Sciences(CAS)CASShanghai200032 China School of chemistry and Materials Science Hangzhou Institute for Advanced StudyUniversity of CAS1 Sub-lane XiangshanHangzhouZhejiang310024 China

Cell-free expression systems have emerged as a versatile and powerful platform for metabolic engineering,biosynthesis and synthetic biology ***,successful examples of the synthesis of complex natural products using this system are still ***,a structurally unique and complex diketopiperazine alkaloid,is a clinically promising antibiotic that selectively inhibits the transcription termination factor ***,we established a modular cell-free expression system with cascade catalysis for the biosynthesis of bicyclomycin from a chemically synthesized *** six cell-free expressed biosynthetic enzymes,including five iron-andα-ketoglutarate-dependent dioxygenases and one cytochrome P450 monooxygenase,were active in converting their substrates to the corresponding *** co-expressed enzymes in the cell-free module were able to complete the related partial *** vitro biosynthesis of bicyclomycin was also achieved by reconstituting the entire biosynthetic pathways(i.e.,six enzymes)using the modular cell-free expression *** study demonstrates that the modular cell-free expression system can be used as a robust and promising platformforthe biosynthesis of complex antibiotics.

关键词： Natural products Bicyclomycin Biosynthesis Iron-andα-ketoglutarate-dependent dioxygenases Cytochrome P450 monooxygenase Cell-freeprotein synthesis Enzyme catalysis