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351.
352.
The purpose of this work is the numerical resolution, in the case of anisotropic elasticity, of the problem of a misfit dislocation located between an infinite substrate and two-layer composite. This case is obtained where the period of a network of misfit dislocations is taken as much greater than the thickness of the two foils. As a result, in the vicinity of the dislocation, the limiting boundary conditions will be close to those of Volterra translation dislocation. The elastic fields of displacement and stress are calculated for various orientations of the burger's vector, by inversion of a 30 x 30 computed matrix. Before this calculation, we tested the precision of the results of the program by comparing the interfacial relative displacement obtained from it with the results of the analytical expression describing this same displacement. The composite NiSi2/Si/(001)GaAs the subject of several investigations, is treated as an example.  相似文献   
353.
A unital Fréchet algebra is called contractible if there exists an element such that and for all where is the canonical Fréchet -bimodule morphism. We give a sufficient condition for an infinite-dimensional contractible Fréchet algebra to be a direct sum of a finite-dimensional semisimple algebra and a contractible Fréchet algebra without any nonzero finite-dimensional two-sided ideal (see Theorem 1). As a consequence, a commutative lmc Fréchet -algebra is contractible if, and only if, it is algebraically and topologically isomorphic to for some . On the other hand, we show that a Fréchet algebra, that is, a locally -algebra, is contractible if, and only if, it is topologically isomorphic to the topological Cartesian product of a certain countable family of full matrix algebras.

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354.
355.
Cycloaddition of nitrones 1 with methylene-gamma-butyrolactones 2, 3 and 4 afforded spiroadducts 5, 6 and 7 with high selectivity. Mixtures of diastereoisomers were usually obtained, whose structures were established by 1H and 13C NMR spectroscopies or X-ray crystallography. Treatment of spiroadducts in acidic and alkaline media led to different, unexpected and novel rearrangements.  相似文献   
356.
357.
We demonstrate that in addition to their role in tuning the wavelength of an N-stage hybrid liquid-crystal Šolc filter, liquid-crystal cells can also be used to vary the transmission bandwidth of such filter around any of the tuned wavelength. This bandwidth tuning is based on the variation of the number of stages by what we call here an “optical cancelling technique”. This is achieved by varying the birefringence of the liquid-crystal cells whose optical path difference switches between two particular values. We show that for a 10-stage filter and at λi = 1.532 μm, the calculated 3-dB bandwidth varies from 2.6 to 11.8 nm when the number of “optically-cancelled” hybrid plates increases from 0 to 8. During the tuning process, the contrast ratio remains equal to that of the equivalent classical Šolc filter.  相似文献   
358.
(C2N2H10)2Mg(HP2O7)2·2H2O, is a new inorganic organic hybrid structure. It has been synthetized using wet chemistry. Its crystal structure consists of cis- and trans-edge sharing [MgO4(H2O)2] octahedra resulting in chains, which are linked via [HP2O7] units to form [Mg(HP2O7)2(H2O)2]4− layers. The Mg2+ cations and the ethylendiammonium cations are located on centers of inversion. The ethylendiammonium cations are alternately located in the interlayer space. The cohesion of the crystal is well ensured by coulombic interactions between anions and cations and by several hydrogen bonds. The diphosphate anion shows an eclipsed conformation.  相似文献   
359.
Research on Chemical Intermediates - Developing environmentally friendly products is a modern science and an important task for today's chemistry and technology scholars. In the present...  相似文献   
360.
A novel approach to two-dimensionally crosslink polydienes at the air/water interface is proposed. The acid-catalyzed condensation of the triethoxysilane pendant groups of triethoxysilane-functionalized polybutadiene chains at the air/water interface successfully led to the formation of an insoluble crosslinked material which could be directly removed from the water surface. The efficiency of the cross-linking reaction was demonstrated through surface pressure measurements such as surface pressure-mean molecular area isotherms recorded at different reaction times and isobar experiments for different subphase pH values. The evolution of the monolayer topography during cross-linking was studied by atomic force microscopy imaging of the Langmuir-Blodgett films.  相似文献   
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