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11.
C. R. Tellier A. J. Tosser L. Hafid 《Applied Physics A: Materials Science & Processing》1980,23(4):357-359
Starting from the bi-dimensional model for grain boundaries in monocrystalline thin films, the difference in thermoelectric
power is expressed in terms of conductivity and energy dependence of the bulk electronic mean free pathU. A new procedure is suggested for measuringU. 相似文献
12.
The approach based on an order-disorder transition model combined with the coulomb electrostatic interaction method allows investigating of the order-disorder phase transition in A(B′B′)O3 complex perovskite type ceramics. An analytical analysis is given on how the second nearest neighbour interactions are connected to the quantities characterising the phase transition. While, the criterion proposed by Zhang et al. (Zhang, X.W., Wang, Q. and Gu, B.L. (1991 ). Study of the order-disorder transition in A(B′B′)O3 perovskite type ceramics. J Am Ceram Soc., 74(11), 2846-2850.) in order to predict the phase transition and the behaviour of the curve which describes the quantity ?′ F ′0 T corresponding to order parameter in function of the ionic radius variation and ionic radius ratio are discussed. 相似文献
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14.
Jean-Claude Champarnaud-Mesjard Bernard Frit Abdeslam Chagraoui Abdelmjid Taïri 《无机化学与普通化学杂志》1996,622(11):1907-1912
Bi2Te2WO10 crystallises in the monoclinic system (space group C2/c, Z = 4) with a = 12.4972(7) Å, b = 5.6414(3) Å, c = 12.2705(6) Å and β = 91.38(3)°. The structure has been solved by means of single crystal X-ray diffraction data analysis. The reliability factors are R1 = 0.030 and wR2 = 0.065 for 1258 structure factors and 70 parameters. The Bi2Te2WO10 crystal structure can be described as a regular stacking along the Ox axis of polyhedral layers with the stereochemically active lone pairs E of the BiIII and TeIV atoms all located between these layers. The cohesion of the three-dimensional network is therefore only ensured between succesive layers by weak Bi? O(5) bonds. 相似文献
15.
Soufiane El Houssame Hafid Anane Larbi El Firdoussi Abdellah Karim 《Central European Journal of Chemistry》2008,6(3):470-476
The palladium(0) catalyzed amination of allylic acetates and carbonates derivatives from terpenic olefins was carried out
under mild conditions. The reaction offers a very good method for the preparation of allylic amines and thus to provide a
useful entry to new functionalized terpenic olefin products. The mechanism involving a formation of p-allyl-palladium intermediate
complex is in good agreement with the results obtained with the optically active substrates, as well as via an analysis of
the observed regio-and stereoselectivity.
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16.
Hafid Anane Soufiane El Houssame Abdelali El Guerraze Abdeladim Guermoune Abderrahim Boutalib Abedellah Jarid Ignacio Nebot-Gil Francisco Tomás 《Central European Journal of Chemistry》2008,6(3):400-403
The complexation energies of H3BNHnCl3−n (n= 3-0) complexes and the proton affinities of NHnCl3−n compounds have been computed at the G2(MP2) level of theory. G2(MP2) results show that the successive chlorine substitution
on the ammonia decreases both the basicity of the NHnCl3−n ligands and the stability of H3BNHnCl3−n complexes. The findings are interpreted in terms of the rehybridisation of the nitrogen lone-pair orbital. The NBO partitioning
scheme shows that the variation of the N-H and N-Cl bond lengths, upon complexation, is due to variation of “s” character
in these bonds.
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17.
Mohamed Nohair Ouafae Britel Nabil Souaf Driss Zakarya Abdelmjid Hafid Noura Mallouk 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):1772-1781
We have used a new, robust model mapping technique—a Bayesian-regularized neural network—to develop a quantitative relationships model for the synthesis of the phosphocalcic hydroxyapatite by precipitation from a calcium carbonate solution and a phosphoric acid solution. This model was preformed by using a set of factors consisting on the pH of reactional medium, the Ca/P molar ratio of the reagents, reaction time, and the initial concentration of calcium. The results show that the method is robust and gives satisfied results. The Levenberg–Marquardt's algorithm implemented in the neural network Matlab's toolbox allowed a drastic improvement of the performance of the model. Very satisfactory results are then obtained by testing the validity by cross-validation technique. We have also turned our interests to the explanatory capacities of our methodology to explore the relative contribution and/or the contribution profile of the input factors by using Garson weight portioning method. 相似文献
18.
Abdeslam Chagraoui Abdelmjid Tairi 《Journal of Physics and Chemistry of Solids》2006,67(11):2241-2252
The new Bi2Te5WO16 compound has been prepared and its structure has been determined by single crystal X-ray diffraction: space group: P2/n (no. 13) with unit cell parameters , , , β=116.68(1)° and Z=2 formula units. The structure was determined from 1975 reflections, the final R1 and Rw indices are 0.037 and 0.071, respectively. The structure derives from the fluorite structure MX2. It can be described as [Bi2Te3O12] layers parallel to (−1 0 1) alternating in the direction [1 0 −1] by WO6 octahedron. The lone pairs of tellurium, active, localised in the pseudo-rectangular tunnels are oriented parallel to Oy-axis between [Bi2Te3O12] layers. 相似文献
19.
Hafid Sayah 《Comptes Rendus Mecanique》2004,332(2):161-168
The differential inclusion describing the quasi-static motion of a supple, homogeneous and inextensible string on a horizontal plane with dry friction (Coulomb's law) is a one dimensional evolution model of a continuous medium, with non-linear geometry, obeying a “plastic-rigid” law. With a view to numerical simulation, we treat the discrete case: the string is assimilated to a chain constituted by rigid rods perfectly articulated around ball-joints. We give variational formulation of the problem and prove existence and uniqueness of solutions. We construct an algorithm that describes the instantaneous solutions when the initial configuration of the string is given. Then, some examples are treated. To cite this article: H. Sayah, C. R. Mecanique 332 (2004). 相似文献
20.
Saliha Loughmari Abderrafia Hafid Aicha Bouazza Abdelaziz El Bouadili Philippe Zinck Marc Visseaux 《Journal of polymer science. Part A, Polymer chemistry》2012,50(14):2898-2905
Polymerization of β‐myrcene with neodymium borohydride‐based coordination catalysts is very efficient, affording poly‐β‐myrcene (polymyrcene, PMy) with high selectivity. With stoichiometric amounts of n‐butylethyl magnesium (BEM) as co‐catalyst, good control over macromolecular data along with cis‐stereoselectivity up to 98.5%, are obtained. In the presence of excess BEM, high level of transfer reactions efficiency between neodymium and magnesium is clearly evidenced whereas the selectivity switches to 3,4‐rich. Combining the neodymium pre‐catalyst with triisobutyl aluminum in the presence of a boron activator affords PMy in good yield, but the polymer material displays low solubility, likely due to the occurrence of crosslinking. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献