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51.
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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52.
An Duong Thi Viet Jourani Abderrahim 《Journal of Optimization Theory and Applications》2022,192(1):82-96
Journal of Optimization Theory and Applications - The aim of the present work is to use a metric intersection formula to estimate the subdifferential of the marginal function in the convex setting.... 相似文献
53.
Journal of Thermal Analysis and Calorimetry - Present communication aims to determine the impact of Cattaneo–Christov model and convective boundary on second-grade nanofluid flow alongside a... 相似文献
54.
We present a new continuous data assimilation algorithm based on ideas that have been developed for designing finite-dimensional feedback controls for dissipative dynamical systems, in particular, in the context of the incompressible two-dimensional Navier–Stokes equations. These ideas are motivated by the fact that dissipative dynamical systems possess finite numbers of determining parameters (degrees of freedom) such as modes, nodes and local spatial averages which govern their long-term behavior. Therefore, our algorithm allows the use of any type of measurement data for which a general type of approximation interpolation operator exists. Under the assumption that the observational measurements are free of noise, our main result provides conditions, on the finite-dimensional spatial resolution of the collected data, sufficient to guarantee that the approximating solution, obtained by our algorithm from the measurement data, converges to the unknown reference solution over time. Our algorithm is also applicable in the context of signal synchronization in which one can recover, asymptotically in time, the solution (signal) of the underlying dissipative system that is corresponding to a continuously transmitted partial data. 相似文献
55.
Ali BH Al-Lawati I Beegam S Ziada A Al Salam S Nemmar A Blunden G 《Natural product communications》2012,7(1):41-44
An aqueous extract of Hibiscus sabdariffa L. is a common beverage in many parts of the world. Reports on its effect on reproduction are conflicting, with anecdotal evidence that the plant is an aphrodisiac, while others report that it is estrogenic, and adversely affects spermatogenesis in rats. We have studied the effect of different concentrations of aqueous extracts of H. sabdariffa calyces (10%, 15% and 20%) used as drinking water for 10 consecutive weeks, and its anthocyanins (50, 100, 200 mg/kg for 5 days, orally) on the weight and histology of the testis, and on some biochemical constituents in testicular homogenates, in addition to the plasma concentrations of testosterone, luteinizing hormone and estradiol. The possible presence of an estrogenic effect of the extract and anthocyanins on the uteri of immature female rats was also tested. Neither the H. sabdariffa extract nor the anthocyanins significantly altered either testicular weight and histology, or uterus weight. Plasma concentrations of the three hormones studied, the testicular concentrations of protein, reduced glutathione and total cholesterol, and superoxide dismutase activity were all insignificantly affected by either the extract or the anthocyanins, except for a slight, but statistically significant, decrease in testicular protein concentration caused by the 15% aqueous extract when compared with controls. These results suggest that H. sabdariffa exerts no adverse effect on the male reproductive system. Consumption of H. sabdariffa aqueous extract inhibited the growth of the rats compared with the controls. 相似文献
56.
Nedjemeddine Bounar Abderrahim BenabbasFarida Bouremmad Patrick RopaJean-Claude Carru 《Physica B: Condensed Matter》2012,407(3):403-407
The Nasicon compounds with the composition LiTi2−xSnx(PO4)3 (x=0-1.8) were synthesised by the solid state reaction. Their structures were determined from X-ray powder diffraction using Rietveld analysis. All the compositions present the space group R-3c. The refinements show that the Ti and Sn cations are statistically distributed over the same position while the Li ones are exclusively located on the M1 site. The lattice constants a and c exhibit linear variation over the whole composition range. The bond lengths are in accordance with those of other Nasicon structures. The SEM micrographs of the samples show relative porous microstructures. The ionic conductivity is about 10−4-10−5 S cm−1; for the activation energy, a typical value of 0.32 eV is obtained for x=0.6 composition whereas significant deviation from linearity in the temperature dependence of the dc conductivity, is observed for the Sn-rich ones. This tendency is discussed along with the structural features. 相似文献
57.
Abdelghni Ouadiay Abderrahim Taitai 《Phosphorus, sulfur, and silicon and the related elements》2013,188(9):1845-1855
L'interaction d'un phosphate de calcium déficient, de structure apatitique, avec le collagéne hydrosoluble en milieu ayant les paramètres physico-chimiques équivalents à ceux du liquide physiologique montre que la fixation du collagène est un phénomène très rapide. Elle est régit par le modèle d'adsorption de Langmuir. L'étude en fonction des configurations probables de la molécule de collagène et des surfaces occupées correspondantes montre que l'adsorption du collagène se fait de façon préférentielle selon la position longitudinale. The interaction of an apatitic, poorly crystallized calcium phosphate with water-soluble collagen in physiological NaCl solution shows that the fixation of collagen is very fast. It can be described by the Langmuir model. The adsorption of collagen occurs preferably in longitudinal position on the calcium phosphate surface. 相似文献
58.
Saïd El Kazzouli Jamal Koubachi Sabine Berteina-Raboin Abderrahim Mouaddib 《Tetrahedron letters》2006,47(48):8575-8577
A cleavage of N-tert-butyloxycarbonyl protection by Na2CO3 is reported. The N-free products are obtained in excellent yields. The compatibility of the method with the presence of acidic or basic groups is demonstrated. The reactions were performed on indole, azaindole, indazole, pyrazole, indolinone, quinolinone, and oxazolone. 相似文献
59.
Anthony Harriman Abderrahim Khatyr Raymond Ziessel 《Research on Chemical Intermediates》2007,33(1-2):49-62
A series of linear polynuclear ruthenium(II) tris(2,2′-bipyridine) complexes has been synthesized whereby individual chromophores are separated by 1,4-diethynylenebenzene subunits bearing alkoxy groups for improved solubility. These arrays contain two, three, four or five metal centers. The compounds are reasonably soluble in polar organic solvents and they possess optical absorption spectral properties that are dominated by transitions associated with the polytopic ligand. Weak luminescence is observed for each complex in deoxy genated acetonitrile at room temperature that appears to be characteristic of emission from a metal-to-ligand charge-transfer triplet state. The emission lifetime is essentially independent of temperature, at least over a modest range. There is no indication for interaction between close-lying triplet states and no obvious sign of a low-energy τ, τ* triplet associated with the polytopic ligand. The photophysical properties suggest that the longer arrays are segmented. 相似文献
60.
Abderrahim Jilale Pierre Netchitaïlo Bernard Decroix Daniel Vegh 《Journal of heterocyclic chemistry》1993,30(4):881-885
Oxodihydrocyclopentathiophenacetic acids 4 , 5 and 6 were synthesized from suitable 2- or 3-formylthiophenes. Reactivity of the carbonyl group or the carboxylic group of these bicyclic systems was investigated. The Beckmann rearrangement of methyl 6-oximino4,5-dihydro-6H-cyclopenta[b]thiophen-4-acetate 12 is an interesting route to methyl 7-oxo-4,5,6,7-tetrahydrothieno[2,3-c]pyridin-4-acetate ( 13 ). 相似文献