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871.
本文通过红外光谱(FT-IR)测量数据和预测数据,计算与研究了十九种长链正烷基脂肪酸(简称脂肪酸或碳酸)的碳链骨架振动能量。结果显示出脂肪酸的碳链骨架振动能量随碳数增加呈阶梯状关系,而且脂肪酸的碳链骨架振动能量∑E出现奇偶数更迭规律。此结果可用来解释脂肪酸的熔点或熔化热呈现奇偶数更迭现象。 相似文献
872.
J. Szeman E. Fenyvesi J. Szejtli H. Ueda Y. Machida T. Nagai 《Journal of inclusion phenomena and macrocyclic chemistry》1987,5(4):427-431
The complex forming ability of a water-soluble -cyclodextrin epichlorohydrin, polymer (CDPS) and its different molecular weight fractions was studied and compared with the complexing properties of -cyclodextrin (CD) and dimethyl-CD (DM-CD). CDPS was separated into two main fractions. CDPS and its fractions formed well soluble inclusion compounds with the studied drugs. The low molecular weight fraction formed rather stable complexes with small guest molecules, the high molecular weight fraction was found to be more efficient in binding larger substrates. Structural studies of furosemide-CD complexes were attempted by NMR spectroscopy.Presented at the Fourth International Symposium on Inclusion Phenomena and the Third International Symposium on Cyclodextrins, Lancaster, U.K., 20–25 July 1986. 相似文献
873.
Absolute small angle X-ray studies of concentration fluctuations were performed in order to determine thermodynamic properties of a model blend, consisting ofn-hexane and perfluoro-n-hexane. The quantities which we determined were the second derivate of the Gibbs free energy of mixing with respect to the concentration of the components, the location of the spinodal, interaction and solubility parameters, the energy gradient density coefficient as well as the correlation length of the fluctuations at various compositions and temperatures, particularly in the neighbourhood of the spinodal and the critical point. The data obtained were compared with those obtainable from the well known location of the binodal, to test the reliability of the scattering method. 相似文献
874.
Winfried Mientus Hans-Georg Bartel Werner Haberditzl Hans-Joachim Spitzer 《Monatshefte für Chemie / Chemical Monthly》1980,111(3):597-606
A normalization of the wave functions by means of the theoretical exact Multiple-Scattering-(MS)-formalism is discussed within the framework of the SCF-X-SW-method. For the atomic and extramolecular regions the integrals of normalization can be easily determined and the results can be described by the corresponding electronic charges. The calculation of the integral of the interatomic region is problematic. The needful volume integration is only necessary to theGreen's functions of the wave functions and can be solved by means of the residual theory. The further analytical calculation of the surface integrals leads to a complicated formalism which can be numerically evaluated. 相似文献
875.
Densities of boldine + alcohol binary mixtures were measured over the whole accessible range of boldine compositions at temperatures from 283.15 to 333.15 K using an Anton-Paar digital vibrating glass tube densimeter. The binary systems studied include, as a solvent, seven normal alcohols from n-C1 to n-C6, n-C8, and isopropanol. The density of these systems has been found an increasing function of the boldine composition. A new methodology based on density data of solutions of solid solutes with normal alcohols is described in order to determine solid molar volume of pure solutes. This methodology was validated with pure solid naphthalene molar volumes data at 298.15 K, with an average uncertainty of 6%. 相似文献
876.
Yingkai Zhang 《Theoretical chemistry accounts》2006,116(1-3):43-50
This perspective article mainly focuses on the development and applications of a pseudobond ab initio QM/MM approach to study enzyme reactions. The following aspects of methodology development are discussed: the approaches for the QM/MM covalent boundary problem, an efficient iterative optimization procedure, the methods to determine enzyme reaction paths, and the approaches to calculate free energy change in enzyme reactions. Several applications are described to illustrate the capability of the methods. Finally, future directions are discussed. 相似文献
877.
A. D. Smirnov 《Journal of Structural Chemistry》2003,44(5):757-762
The vibrational, rotational, and centrifugal constants have been calculated for the ground electronic states of KRb and RbCs molecules. The calculation is performed using the semiempirical potential curves constructed in a wide range of internuclear distances. The estimated spectroscopic constants are compared with experimental data. 相似文献
878.
Peter D. Dacre 《Theoretical chemistry accounts》1976,43(2):197-205
The direct CI method, which avoids explicit calculation of the Hamiltonian matrix, is presented in a new form. The method is linked with Davidson's algorithm for iterative evaluation of the ground state eigenvector. The viability of the method is indicated by the test calculations on water which are described. 相似文献
879.
880.
R. Pikl U. Posset S. Möller R. Lankat W. Malisch W. Kiefer 《Vibrational Spectroscopy》1996,10(2):161-167
In order to examine the influence of the transition metal on the metal-silyl fragment MSiH3 and the metal-silicon bond, polarized Raman spectra of the complexes (C5R5)(CO)2FeSiH3 R = H (Cp) (1a), Me (Cp*) (1b)], (C5H5)(CO)(PPh3)FeSiH3 (1c), (C5Me5)(CO)2RuSiH3 (2), (C5R5)(CO)2(PMc3)MoSiH3 [R = H (3a), Me (3b)], and (C5R5)(CO)2(PMe3)WSiH3 [R = H(4a), Me (4b)] have been recorded. The spectral data have been evaluated and interpreted on the basis of a normal coordinate analysis of the MSiH3 core and the derived force constants and potential energy distributions were compared to results obtained for analogous halogen derivatives in the series XSiH3 [X = Br (5), I (6)]. 相似文献