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11.
Néji Besbes Houyem Jellali Patrick Pale Ezzeddine Srasra Mohamed Lotfi Efrit 《Comptes Rendus Chimie》2010,13(3):358-364
The silica gel, neutral alumina and acid activated clays transform the N-acyl-2,2-dimethylaziridines 1 into a mixture of N-methallylamides 2, oxazolines 3 and amidoalcohols 4. The reaction of N-benzoyl-2,2-dimethylaziridine with benzylcyanid anion leads to a mixture of amidopyrroline 5 and iminopyrrolidine 6. The product 5 was converted into its tautomer 6 by chromatogaphy on silica gel. Ionic mechanisms were then proposed to explain the formation of products 2–6 resulting from the regioselective ring opening on the more substituted C2 carbon side. 相似文献
12.
Samiha SalmaouiFaouzi Sediri Néji GharbiChristian Perruchot Salah AeiyachIwona A. Rutkowska Pawel J. KuleszaMohamed Jouini 《Applied Surface Science》2011,257(19):8223-8229
Tungsten trioxide, unhydrated with hexagonal structure (h-WO3), has been prepared by hydrothermal method at a temperature of 180 °C in acidified sodium tungstate solution. Thus prepared h-WO3 has been characterized by X-ray diffraction (XRD) method and using electrochemical techniques. The morphology has been examined by scanning and transmission electron microscopies (SEM and TEM) and it is consistent with existence of nanorods of 50-70 nm diameter and up to 5 μm length. Cyclic voltammetric characterization of thin films of h-WO3 nanorods has revealed reversible redox behaviour with charge-discharge cycling corresponding to the reversible lithium intercalation/deintercalation into the crystal lattice of the h-WO3 nanorods. In propylene carbonate containing LiClO4, two successive redox processes of hexagonal WO3 nanorods are observed at the scan rate of 50 mV/s. Such behaviour shall be attributed to the presence of at least two W atoms of different surroundings in the lattice structure of h-WO3 nanorods. On the other hand, in aqueous LiClO4 solution, only one redox process is observed at the scan rate of 10 mV/s. The above observations can be explained in terms of differences in the diffusion of ions inside two types of channel cavities existing in the structure of the h-WO3 nanorods. Moreover, the material can be applied as active support for the catalytic bi-metallic Pt-Ru nanoparticles during electrooxidation of ethanol in acid medium (0.5 mol dm−3 H2SO4). 相似文献
13.
Summary For two-electron atoms, the method of a variable exponent, which treats the orbital exponent (or effective nuclear charge) of an electron as an explicit function of the radial coordinate of the other electron, is studied. The method is shown to improve the energy and other electronic properties remarkably. An incorporation of the variable exponent into the Kellner approximation for He, for example, gives the energy –2.872 606 1 a.u., which is lower than the original Kellner energy by 0.024 949 8 a.u. and exceeds the Hartree-Fock limit energy by 0.010 926 1 a.u. The improvement due to the variable exponent originates from the inclusion of the charge and radial correlations. Applications of the method to the Eckart and Hylleraas approximations are also presented. 相似文献
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Yūji Sakai 《Journal of Mathematical Analysis and Applications》1985,108(1):31-46
The equation (A▽4 + B▽2 + C)χ = 0 with matrix coefficients A, B, C is studied for homogeneous boundary conditions. An integral constraint is derived for the above system leading to a relationship between the matrices involved. As a consequence, known as well as unknown results are obtained for some problems of hydrodynamic stability in a unified manner. Finally, another method of unification is suggested. 相似文献
17.
P. Hájiček 《Communications in Mathematical Physics》1974,36(4):305-320
In the first remark the catalogue of axisymmetric stationary horizons is completed by a subset of uncharged translation-symmetric horizons, which was ignored in the previous paper [5]. The subset consists of two one-parameter families: extreme Kerr horizon (a=m) and a more symmetric family. In the second remark the surface area, net angular momentum and net charges of a black hole are computed. It turns out that the four invariant functionsA, B, C, D used in [5] to classify the horizons describe, at least formally and up to a constant factor:A the profile of the black hole surface,B the surface density of angular momentum andC cosD, C sinD the surface density of electric and magnetic charge. In the third remark a simplified model of a black hole surrounded by a charged matter shell is found to satisfy a sort of generalized “no-hair-conjecture”. An example of a non-Kerr-Newman field around a horizon is provided; the magnetic field in it is hoped to have some astrophysical importance. 相似文献
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The aim of this paper is to prove an uncertainty principle for the basic Bessel transform of order
. In order to obtain a sharp uncertainty principle, we introduce and study a generalized q-Bessel-Dunkl transform which is based on the q-eigenfunctions of the q-Dunkl operator newly given by:
In this work, we will follow the same steps of Fitouhi et al. (Math. Sci. Res. J., 2007) using the operator T
α,q
instead of the q-derivative.
相似文献