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891.
The title compound is used to prepare 3-arylglutaric acids, bis-isoxazoles and bis-pyrazoles from commercially available materials. The methodologies described have afforded important synthetic intermediates in high yields and without the use of chromatography. 相似文献
892.
893.
We investigate the dispersive properties of evolution equations on waveguides with a non-flat shape. More precisely, we consider an operator $$H=-\Delta_{x}-\Delta_{y}+V(x,y)$$ with Dirichlet boundary conditions on an unbounded domain ??, and we introduce the notion of a repulsive waveguide along the direction of the first group of variables, x. If ?? is a repulsive waveguide, we prove a sharp estimate for the Helmholtz equation Hu???u?=?f. As consequences, we prove smoothing estimates for the Schr?dinger and wave equations associated to H, and Strichartz estimates for the Schr?dinger equation. Additionally, we deduce that the operator H does not admit eigenvalues. 相似文献
894.
A three-component one-pot procedure (3-MCR) was developed to assemble the spiroisoxazoline nucleus from commercially available materials. This new methodology affords the title compounds in high yields and without the use of chromatography. 相似文献
895.
896.
The electron density distribution in a transition-metal dimer containing a semibridging carbonyl is determined through experimental X-ray diffraction and quantum chemical computations. The changes occurring during the evolution from terminal to bridging coordinations are described by a "structure-correlation-like" approach and by a theoretical investigation along the conversion path. The smooth continuum of conformations observed in the solid state is explained in terms of the mutual interplay of direct M-M and M-CO and indirect M- - -M and M- - -C interactions, which can be characterized by interatomic delocalization indexes, within the framework of Quantum Theory of Atoms in Molecules. 相似文献
897.
898.
Piero Buzano 《Annali di Matematica Pura ed Applicata》1962,58(1):35-40
Sunto Si dimostra che se y è un punto della traiettoria di x in un sistema ∞1 di omografie (contenente l'identità) e se la stessa omografia che porta x in y fa corrispondere le relative tangenti, il
sistema è un gruppo oppure è formato da omologie con lo stesso centro.
A Enrico Bompiani in occasione del suo Giubileo scientifico 相似文献
899.
900.
Roberto Della Pergola Luigi Garlaschelli Carlo Mealli Davide M. Proserpio Piero Zanello 《Journal of Cluster Science》1990,1(1):93-106
Electrochemical studies show that it is possible to move step-wise and reversibly between the redox congeners of the series [Fe3Pt3(CO)15]
n
,n=2-/1-/0. By contrast, a multielectron reduction of the dianion leads to an irreversible demolition of the species. When [Fe3Pt3(CO)15]2– is treated with one or two equimolar amounts of the oxidant [Fe(C5H5)2]+, the oxidized species (n=1- andn=0) can be also obtained. It can be established or extrapolated from the already known structures of the dianion and the monoanion that the successive oxidations strengthen the inner Pt-Pt linkages of the overall quasiplanar Fe3Pt3 skeleton. MO analysis, by establishing the antibonding nature of the frontier level from which the electrons are added or subtracted, allows the correlation of the bonding features of the inner Pt3 skeleton with the redox propensities of the system. 相似文献