摘要:

AbstractThe band structures of Group IVB (Ti, Zr, Hf), VB (V, Nb, Ta) and V1B (Cr, Mo, W) transition metals and some of their carbides and nitrides (TiN, ZrN, HfN, VC, NbC, TaC, VN, NbN, TaN) with NaCl‐type (Bl‐type) structure have been calculated by using the tight‐binding method within the Extended Hückel approximation (EHT). The energy bands, densities of states and crystal orbital overlap populations are given. The relationship between the bonding properties and the superconducting transition temperatures (Tc) of them is discussed. The influences of various kinds of metallic atoms and changes of bond lengths onTcare also dis

ISSN:1001-604X    

DOI:10.1002/cjoc.19960140502

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1996

数据来源: WILEY

摘要:

AbstractWe present here a systematically theoretical study on the nonlinearities and their structure‐property relationship of cyanovinyl‐substituted donor‐acceptor molecules by virtue of semiempirical PM3/AM1‐FF approach. Good consistency between measured and calculated hyperpolarizabilities is obtained. Results show that conformation has a significant effect on hyperpolarizabilities. The torsion angle change between two conjugated parts of the molecular systems can substantially alter the nonlinearities. The total amount of charge transfer difference from donor to acceptor has been introduced to understand the microscopic nature of the nonlinear optical properties for the title molecules. General guidelines may be sought out in the search of molecules with large values of β. Some molecules with large molecular hyperpolarizabilities can be predicted by the optimization for the longer δ‐electron systems with both acceptor and d

ISSN:1001-604X    

DOI:10.1002/cjoc.19960140503

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1996

数据来源: WILEY

摘要:

AbstractLuminescence of europium (III), europium(II) and terbium(III) has been observed in Ba3(PO4)2:Eu, Tb phosphors which are synthesized in air atmosphere. The valence state of europium is influenced by amount of terbium. It is notable that the relative intensity of the emission spectra peaks corresponding to Eu2+is increased if the amount of Tb3+is increased. These phenomena can be explained by an electron transfer mechanism. We predict a new kind of two‐rare‐earth codoped trichromatic phosphors in Ba3(PO4)2mat

ISSN:1001-604X    

DOI:10.1002/cjoc.19960140504

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1996

数据来源: WILEY

摘要:

AbstractAn enzyme biosensor was constructed using a plate platinum electrode and immobilized xanthine oxidase (XOD). Only a very small quantity of enzyme was chemically immobilized on a special silk net. Hydrogen peroxide released during the enzymatic reaction was detected by the electrode at +0.65 V (vs. Ag/AgCl). The electrode was very sensitive to hypoxanthine and its detection limit was 1×10–7mol/L. When it was applied to the determination of fish freshness, the results agreed well with those obtained by traditional methods‐determination of total volatile basic nitrogen (TVB‐N) and microbial count. A range for estimating the freshness of river fish was sug

ISSN:1001-604X    

DOI:10.1002/cjoc.19960140505

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1996

数据来源: WILEY

摘要:

AbstractPhotophysical properties of a porphyrin‐phthalocyanine heterodimer covalently linked with a dipentoxy chain have been studied. Absorption spectra show that there is weak exciton coupling between the two chromophores in the ground state. Fluorescence spectra show that intramolecular energy transfer from porphyrin to phthalocyanine moiety occurs in competition with electron transfer. The efficiency of these two processes depends upon the mutual orientation of the two chromophores. The effect of solvent polarity on the intramolecular processes is also discusse

ISSN:1001-604X    

DOI:10.1002/cjoc.19960140506

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1996

数据来源: WILEY

摘要:

AbstractIn this paper, a novel solid state Michael‐type addition reaction ofN‐heterocyclic compounds containing the active‐CH group was investigated. 3‐Methyl‐l‐phenyl‐5‐pyrazolone (MPP) and indole (In) reacted with 4‐arylmethylene‐3‐methyl‐l‐phenyl‐5‐pyrazolone (1) in the solid state at room temperature to give the corresponding adducts, aryl‐4,4′‐bis(5‐hydroxy‐3‐methyl‐l‐phenylpyrazolyl) methane (2a—n) and l‐aryl‐l‐(5′‐hydroxy‐3′‐methyl‐L'‐phenyl‐4′‐pyrazolyl)‐l‐(3′‐indolyl) methane (Sa—n), respectively. This is a feasible method f

ISSN:1001-604X    

DOI:10.1002/cjoc.19960140507

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1996

数据来源: WILEY

摘要:

AbstractNew complexes, of bis(2,2′‐diamino‐4,4′‐bithiazole)sulfate nickel(II) and bis(2,2′‐diamino‐4,4′‐bithiazole)sulfate cobalt(II), have been prepared. The complexes were characterized by infrared and UV‐Vis spectroscopy,1H NMR, elemental analyses and molar conductivity. The effect of these complexes on the DNA synthesis of sarcoma 180 cells has been studied by the technique of isotopic liquid scintillation. The results indicated that complexes show ability to inhibit DNA synthesis of the tumor cells. In order to provide a molecular basis for understanding the biological effects, the probe, [trans‐en2Os(2‐H2)](CF3SO3)2(en, ethylenediamine) as a monitor was first used to explore interaction of the complexes with 2′‐deoxyguan

ISSN:1001-604X    

DOI:10.1002/cjoc.19960140508

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1996

数据来源: WILEY

摘要:

AbstractConversion of β‐aroyl propionic acids into furanone derivatives (2) and benzoxazinone derivatives (3) for the study of the reactivity of these nucleus towards different nucleophilic and electrophilic reagen

ISSN:1001-604X    

DOI:10.1002/cjoc.19960140509

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1996

数据来源: WILEY

摘要:

Abstract4′, 5′‐Dibromc‐o‐xylyl‐17‐crown‐5 ether (2BrB17C5) was synthesized, starting from 1,2‐dibromo‐4,5‐bis(bromomethyl)‐benzene and tetraethylene glycol, and was characterized by1H NMR, MS and elemental analysis. Pale yellow prismatic single crystal obtained from anhydrous ethanol was investigated by X‐ray structural analysis. The complexation properties toward alkali metal ions were examined using the solvent extraction method and UV absorption spectroscopy. The crown ether was found to be conformationally deformed and oblate‐like and is highl

ISSN:1001-604X    

DOI:10.1002/cjoc.19960140510

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1996

数据来源: WILEY

摘要:

AbstractMethyl 3‐deoxy‐3‐(diphenylphosphino)‐4,6‐O‐benzylidene‐α‐D‐altropyranoside (1) and methyl 2‐deoxy‐2‐(diphenylphosphino)‐4,6‐O‐benzylidene‐α‐D‐altropyranoside (2) were prepared from methyl 2,3‐anhydro‐4,6‐O‐benzylidene‐O‐D‐mannopyranoside and methyl 2,3‐anhydro‐4,6‐O‐benzylidene‐α‐D‐allopyranoside, respectively, via regioselective and stereospecific ring‐opening reactions in high yields. Compounds 1 and

ISSN:1001-604X    

DOI:10.1002/cjoc.19960140511

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1996

数据来源: WILEY