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排序方式: 共有401条查询结果,搜索用时 15 毫秒
1.
Zygmunt Bak 《Czechoslovak Journal of Physics》2002,52(1):A25-A28
We consider RKKY interaction in a quasi 2D system with nonparabolic dispersion. In our paper we calculate the RKKY range function assuming the in-layer confinement via effective dimensionality approach. We show, that indirect magnetic exchange in our system can be modelled by the effective spectral dimension which equals one. 相似文献
2.
Børge Bak Niels A. Kristiansen Henrik Svanholt Arne Holm Steen Rosenkilde 《Chemical physics letters》1981,78(2):301-303
Microwave Spectra of 13CH212C80,78Se and 12CH213C80,78Se (selenoketene) are recorded. B 5-13C-1,2,3-selenadiazole all four species are formed. The 13C scrambling may take place via a three-membered ring, selenirene, but as expected its microwave spectrum was not observed. 相似文献
3.
Wiosetek-Reske AM Wysocki S Bak GW 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,62(4-5):1172-1178
The absorption and fluorescence spectra of N-nonyl acridine orange are determined at room temperature (298 K) in cyclohexane, benzene, carbon tetrachloride, chloroform, chlorobenzene and dichloromethane. The ground state of dipole moment was obtained by impedance measurements using Guggenheim-Debeye's method. The experimental excited state dipole moment of N-nonyl acridine orange was determined using Bakhshiev's and Kawski-Chamma-Viallet's formulae and solvent polarity parameter proposed by Reichardt. These experimental results were completed with theoretical results using quantum chemical methods. The experimental (muexp=10.76 D) and theoretical (mucal=9.9 D) dipole moments in the ground and excited state (muexp*=14.56 D) were compared. 相似文献
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Wlodzimierz Kutner Winfried Storck Karl Doblhofer 《Journal of inclusion phenomena and macrocyclic chemistry》1992,13(3):257-265
The preparation and properties of smooth and stable films of cyclodextrin polymers are described. The commercially available water soluble prepolymers of-, -, and-cyclodextrin of low molecular masses were crosslinked with glutaric dialdehyde. Side-chain unreacted aldehyde groups were reduced with sodium borohydride. For the-cyclodextrin polymer, optimum film performance was found for a 1:10 mass ratio of glutaric dialdehyde to prepolymer, which corresponds to a molar ratio of glutaric dialdehyde to cyclodextrin units of about 1.75: 1. Such films, of thickness 2.4 µm, were prepared on metallic or glassy-carbon substrates for characterization by scanning-electron microscopy, and for studies with the electrochemical quartz-crystal microbalance. 相似文献
8.
Galezowski W 《Inorganic chemistry》2005,44(15):5483-5494
A two-step mechanism of the reaction of CH(3)Co(III)Pc (Pc = dianion of phthalocyanine) with thiophenoxides in DMA has been confirmed, and the visible spectrum of the inactive transient, CH(3)Co(III)Pc(SAr)(-), has been determined. Rapid rates for ligation of CH(3)Co(III)Pc, yielding CH(3)Co(III)Pc(S-C(6)H(4)-X)(-), are virtually independent of X; this step proceeds probably by an I(d) mechanism. Kinetic data for the follow-up methyl-transfer step yield second-order rate constants and stability constants for CH(3)Co(III)Pc(S-C(6)H(4)-X)(-) consistent with those estimated from concentration dependence of the amplitude of the ligand-exchange step. Cyclic voltammetry provides first reduction potential for CH(3)Co(III)Pc(DMA) of -1.42 V vs Fc(+)/Fc, which makes an OSET mechanism unlikely. Homolytic decay of CH(3)Co(III)Pc(SAr)(-) has also been ruled out. All of the kinetic data, including Hammett's rho = -2.3 +/- 0.1, N-donor inhibition, and alkyl group effect, Me > Et, indicate that the reaction is a normal S(N)2 methyl transfer, only very fast. Methyl transfer to aliphatic thiolates is also rapid and follows the same S(N)2 mechanism. Exceptional methyl-transfer reactivity of the phthalocyanine model sharply contrasting with the inertness of methylcobaloxime is explained. 相似文献
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Piotr Kirszensztejn Wlodzimierz Zmierczak 《Reaction Kinetics and Catalysis Letters》1994,52(2):467-474
This study is concerned with the effect of various amounts of Sn species in modifying the dispersity of Al2O3–SnO2 supported platinum catalysts by application of hydrogen chemisorption in a pulse chromatographic system, as well as determination of activity in water-gas shift reaction (WGS). 相似文献