摘要:

AbstractA convenient, efficient and general method has been developed for synthesis of H‐phosphonate mono and diesters of AZT and d4T through one‐pot reaction of phosphonic acid with AZT or d4T and different alcohols using pivaloyl chloride as condensing agent under mild conditi

ISSN:1001-604X    

DOI:10.1002/cjoc.20040220302

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

年代:2004

数据来源: WILEY

摘要:

AbstractNi—W alloy was electrodeposited from the electrolyte solution containing sodium tungstate, nickel sulfate and ammonium citrate. The electrodeposition, heat treatment, structure, surface morphology and corrosion resistance in w=0.03 NaCl solution, of Ni—W alloys were studied by means of DSC, XRD, SEM and electrochemical techniques. The results showed that the obtained Ni—W alloy electrodeposit with W weight content (ww=0.471) was presented in more typical nanocrystalline. After heat treatment at 400 C for 1 h, the phase structure of the deposits was not obviously changed whereas the agglomerate for the reunion of tiny grains on deposit surface caused the granule in a more smooth morphology, the microhardness was slightly increased and the corrosion resistance was enh

ISSN:1001-604X    

DOI:10.1002/cjoc.20040220303

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

年代:2004

数据来源: WILEY

摘要:

AbstractThe synthesis and crystal structure of Li3AlB2O6with different cell parameters are reported and these cells are transformed each other from the confirmation of crystallographic structural analyses. The absorption spectrum, luminescence and lifetimes of the Li3AlB2O6and LiSrBO3solid compounds are measured and the comparisons are made between them. It is shown that the absorption edges are at about 400 run (or band gap 3.1 eV) and there is one of absorption peaks at about 350 run for the Li3AlB2O6and LiSrBO3. The emission band (530 nm) makes a red shift and fluorescence decay time (24.39 ns) of the Li3AIB2O6 becomes smaller compound with the emission band (480 nm) and lifetime (93.16 ns) of the LiSrBO3 at the visible region. The transition energies and oscillator strengths of the clusters (Li3AlB2O6)2and (LiSrBO3)2lying at low excited states are calculated by the time‐dependent Har‐tree‐Fock method. The obtained results arc used to model the photophysical properties and discuss the origin of spectral bands of the Li3AlB2O6and Li

ISSN:1001-604X    

DOI:10.1002/cjoc.20040220304

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

年代:2004

数据来源: WILEY

摘要:

AbstractThe transport properties of fluid argon in rnicropores.i.e. diffusivity and viscosity. were studied by molecular dynamics simulations. The effects of pore width, temperature and density on diffusivity and viscosity were analyzed in micropores with pore widths from 0.8 to 4.0 run. The results show that the diffusivity in micropores is much lower than the bulk diffusivity, and it decreases as the pore width decreases; but the viscosity in micropores is significantly larger than the bulk one, and it increases sharply in narrow micropores. The diffusivity in channel parallel direction is obviously larger than that in channel perpendicular direction. The temperature and density are important factors that obviously affect diffusivity and viscosity in micropores.

ISSN:1001-604X    

DOI:10.1002/cjoc.20040220305

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

年代:2004

数据来源: WILEY

摘要:

AbstractDifferent types of stilbene derivatives (D‐‐D, A‐‐A, D‐‐A) were investigated with AM1, and specially, equilibrium geometries of symmetrical stilbene derivatives (D‐‐D) were studied using of PM3. With the same method INDO/CI, the UV‐vis spectra were explored and the position and strength of the two‐photon absorption were predicated by Sum‐Over‐States expression. The relationships of the structures, spectra and nonlinear optical properties have been examined. The influence of various substituents on two photon absorption cross‐sections was di

ISSN:1001-604X    

DOI:10.1002/cjoc.20040220306

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

年代:2004

数据来源: WILEY

摘要:

AbstractNa+/K−‐ATPasc(EC 3.6.1.3) is an important membrane‐bound enzyme. By using microcalorimetry, the thermokinetic method was developed to kinetic studies on Na+/K+‐ATPasefor the first time. Compared with other ones, the method provided accurate measurements of not only thermodynamic data but also the kinetic data. At 310.15 K and pH=7.4, the molar reaction enthalpy ΔrHm, was measured as (‐40.408k 1.9) kJ mol−1. The Michaelis constantKmwas determined to be (0.479 0.020) 10−‐3mol L−1and consistent with literature figure which is about 0.5 10−‐3moi L−1. The maximum velocityVmaxobtained was (0.6810.026) μmol Pimin−1mg protein−1. All of the data have good repeatability and self‐consistency. The reliability of thermokinetic method was verified by the experimental results and further confirmed by colorimetric studies. Moreover. the effect of enzyme pre‐dilution on its

ISSN:1001-604X    

DOI:10.1002/cjoc.20040220307

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

年代:2004

数据来源: WILEY

摘要:

AbstractSelf‐assembly of platinum nanoparticles were applied to fabrication of counter electrode for dye‐sensitized solar cells on conductive oxide‐coated glass substrate. The present Pt electrode exhibits high exchange current density of 220 mA/cm2, which is comparable to those prepared by electrodeposition. magnetron sputtering or thermal decomposition of platinum chloride. After analysis by transmission electron microscopy (TEM). atomic force microscopy (AFM) and X‐ray photoelectron spectroscopy (XPS), it was found that the catalyst was structurally characterized as nanosized platinum metal clusters and was continuously arranged on electrode surface. The present nanostructure electrode had high electrocatalytic activity for the reduction of iodine in organic s

ISSN:1001-604X    

DOI:10.1002/cjoc.20040220308

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

年代:2004

数据来源: WILEY

摘要:

AbstractK2AgIn3Se6was synthesized by a molten‐salt (alkali‐metal polyselenide flux) reaction at 500 C. The orange red granular crystal crystallizes in monoclinic space groupC2/cwith cell parameters,a=1.16411(7) nm,b=1.16348(8) nm, c=2.14179(12) nm, V=2.8740(9) nm3, and Z=8. The crystal has a new two‐dimensional structure containing2‐−[AgInSe6]2‐−anionic layers separated by K+cations and the2‐−[AgIn3Se6]2‐−layer is constructed with comer‐shared [AgSe4] and [InSe4] tetrahedra. The optical band gap of K2AgIn3Se6was determined to beca. 2.9 eV by UV/vis/NIR diff

ISSN:1001-604X    

DOI:10.1002/cjoc.20040220309

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

年代:2004

数据来源: WILEY

摘要:

AbstractA new heterometallic complex K2[{Eu(H2O)4}2{Fe11(bipy)(CN)4}4] 9H2O CH3OH [bipy=2,2′‐bipyridine] was synthesized. The compound has been characterized by X‐ray structure analysis, elemental analyses, IR spectrum, TGA thermogram and magnetic susceptibility. The complex consists of novel one‐dimensional ladder structure. The crystal belongs to monoclinic system with a space groupP21/c. a=1.3946(4) nm, b=2.0450(6) nm. c=2.9722(8) nm. β=99.W(5), V=8.372(4) nm3, Z=4. Dc= 1.56

ISSN:1001-604X    

DOI:10.1002/cjoc.20040220310

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

年代:2004

数据来源: WILEY

摘要:

AbstractThe relationship among intrinsic surface reaction constant (K) in 1‐pK model, point of zero net charge (PZNC) and structural charge density (σst) for amphoteric solid with structural charges was established in order to investigate the effect of σstonpK. The theoretical analysis based on1‐pKmodel indicates that the independent PZNC of electrolyte concenmtion (c) exists for amphoteric solid with structural charges. A common intersection point (CIP) should appear on the acid‐base titration curves at different c. and the pH at the CIP is pHPZNC. ThepKcan be expressed as pK=‐pHPZNC+log[(l+2αPZNC)/(1–2αPZNC)], where α‐PZNCσ/eNANs, in whicheis the elementary charge, Nathe Avogadro's constant and NSthe total density of surface sites. For solids without structural charges,pK=‐pHPZNC. The pK values of hydrotalcite‐like compounds (HTlc) with general formula of [Mg1‐xFex(OH)2](Cl, OH)xwere evaluated. With increasingx. the pK increases, which can be explained based on the affinity of metal cations for H−or OH−and the electrostatic interaction between ch

ISSN:1001-604X    

DOI:10.1002/cjoc.20040220311

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

年代:2004

数据来源: WILEY