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排序方式: 共有80条查询结果,搜索用时 31 毫秒
11.
Mohamed Amine Bencheikh Le Hocine Salah Boulaaras Mohamed Haiour 《Numerical Functional Analysis & Optimization》2016,37(1):1-18
In this article, an optimal error estimate for parabolic variational inequalities is studied. Existence and uniqueness of the solution is provided by the introduction of a constructive algorithm. An optimally L∞-asymptotic behavior in uniform norm is proved using the semi-implicit time scheme combined with the finite element spatial approximation. The approach is based on the concept of subsolutions. 相似文献
12.
Even though carbon nanotubes offer an excellent solution for the design of strain sensors, their widespread commercial utilization has been hampered by the unavailability of design rules, inconsistencies in their macro-scale properties, and lack of understanding of the effects of various parameters on their characteristics. Nevertheless, many researches have been carried out to characterize elastomeric nanocomposites filled with carbon nanotubes in order to optimize their properties such as electrical conductivity and strain sensitivity range. This article reviews the effect of different parameters on the electrical properties of such nanocomposites, followed by the analysis of performances of elastomer strain sensors. 相似文献
13.
3‐Methyl‐1,2,4‐benzotriazine and some of its derivatives were prepared in moderate yields (50–70%) via a reductive cyclization by a PtO2‐catalyzed hydrogenation of the corresponding 2‐nitrophenylhydrazones of the pyruvic acid. The latter compounds were obtained in yields higher than 90% by reacting 2‐nitrophenylhydrazines with sodium pyruvate salt. Three 3‐phenyl‐1,2,4‐benzotriazine compounds were also produced via a reductive cyclization by a Pt/C‐catalyzed hydrogenation of their corresponding 2‐nitrophenylhydrazono‐ethers in high yields (>70%). © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:166–172, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20200 相似文献
14.
Samia Lamraoui Rachid Bensalem Khadidja Hacini Hocine Meradji Sebti Ghemid Fouad El Haj Hassan 《Central European Journal of Physics》2014,12(1):70-79
Structural, electronic and thermal properties of Zn1?x Mg x S ternary alloys are studied by using the full potential-linearized augmented plane wave method (FP-LAPW) within the density functional theory (DFT). The Wu-Cohen generalized gradient approximation (WC-GGA) is used in this approach for the exchangecorrelation potential. Moreover, the modified Becke-Johnson approximation (mBJ) is adopted for band structure calculations. The dependence of the lattice constant, bulk modulus and band gap on the composition x showed that the first exhibits a small deviation from the Vegard’s law, whereas, a marginal deviation of the second from linear concentration dependence (LCD). The bowing of the fundamental gap versus composition predicted by our calculations agrees well with the available theoretical data. The microscopic origins of the gap bowing are explained by using the approach of Zunger and co-workers. Thermal effects on some macroscopic properties of Zn1?x Mg x S alloys are also investigated using the quasi-harmonic Debye model, in which the phononic effects are considered. As, this is the first quantitative theoretical prediction of the thermal properties of Zn1?x Mg x S alloys, no other calculated results and furthermore no experimental studies are available for comparison. 相似文献
15.
Faouzi Guenadil Hocine Aichaoui 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):1703-1708
In this work we report another method of acylation on the 6-position of the 2(3H)-benzothiazolone ring with Fries-like rearrangement catalyzed by zinc chloride instead of aluminium chloride and 3-acyl-2(3H)-benzothiazolones derivatives as starting materials. This method is advantagous in regard to other acylation methods as it requires only three equivalents of ZnCl 2 to produce 6-acyl-derivatives with yields of 82-94%. 相似文献
16.
Nardjes Mouas Toma Jean‐Claude Daran Hocine Merazig Eric Manoury 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(5):460-464
In our ongoing development of ferrocene ligands, 1‐dimethylamino‐2‐(diphenylphosphinothioyl)ferrocene is being used as a convenient building block to obtain racemic or enantiomerically pure ligands. Using this building block in large excess allowed the formation of several by‐products, two of which have already been reported; the structure of a third by‐product, namely 1‐(diphenylphosphinothioyl)‐2‐{[(diphenylphosphinothioyl)sulfanyl]methyl}ferrocene, [Fe(C5H5)(C30H25P2S3)], is presented here. The crystal structure is built up from a ferrocene unit, with one of the cyclopentadienyl (Cp) rings substituted in the 1‐ and 2‐positions by a protected diphenylphosphinothioyl group and a [(diphenylphosphinothioyl)sulfanyl]methyl fragment, –CH2SP(=S)Ph2. There are C—H...S interactions which result in the formation of chains parallel to the c axis. After desulfurization, the crude material was then reacted with Pd and Pt (M) precursors [MCl2(CH3CN)2] to yield two isostructural dinuclear complexes arranged around twofold axes, namely (R,R/S,S)‐bis{μ‐[2‐(diphenylphosphanyl)ferrocen‐1‐yl]methanethiolato‐κ3P,S:S}bis[chloridopalladium(II)] pentane disolvate, [Pd2{Fe(C5H5)(C18H15PS)}2Cl2]·2C5H12, and the platinum(II) analogue, (R,R/S,S)‐bis{μ‐[2‐(diphenylphosphanyl)ferrocen‐1‐yl]methanethiolato‐κ3P,S:S}bis[chloridoplatinum(II)] toluene monosolvate, [Pt2{Fe(C5H5)(C18H15PS)}2Cl2]·C7H8, in which the two metal atoms present a slightly distorted square‐planar geometry formed by two bridging S atoms and P and Cl atoms. The P,S‐chelating ligand results from the rupture of one of the P—S bonds in the starting ligand. These dinuclear complexes display a butterfly geometry. Surprisingly, only the (R,R/S,S) diastereoisomer has been isolated. 相似文献
17.
Louaar S Achouri A Lefahal M Laouer H Medjroubi K Duddeck H Akkal S 《Natural product communications》2011,6(11):1603-1604
Six flavonoids, namely 6-methoxykaempferol (1), 6-methoxykaempferol 7-O-glucoside (2), kaempferol 7-O-glucoside (3), 6-methoxyluteolin (4), patuletin 7-O-glucoside (5), and hispidulin 7-O-glucoside (6), were isolated from a n-butanolic fraction of Centaurea microcarpa Coss et Dur. flowers. This work describes for the first time the phytochemical composition of this endemic Algerian plant. 相似文献
18.
Hocine Guediri 《数学学报(英文版)》2013,29(9):1791-1808
Dual Toeplitz operators on the Hardy space of the unit circle are anti-unitarily equivalent to Toeplitz operators. In higher dimensions, for instance on the unit sphere, dual Toeplitz operators might behave quite differently and, therefore, seem to be a worth studying new class of Toeplitz-type operators. The purpose of this paper is to introduce and start a systematic investigation of dual Toeplitz operators on the orthogonal complement of the Hardy space of the unit sphere in Cn . In particular, we establish a corresponding spectral inclusion theorem and a Brown-Halmos type theorem. On the other hand, we characterize commuting dual Toeplitz operators as well as normal and quasinormal ones. 相似文献
19.
20.
Lynda Idjouadiene Toufik A. Mostefaoui Hocine Djermoune Letizia Bonizzoni 《X射线光谱测定》2019,48(5):505-512
The North African regions boast a multimillenary tradition of pottery production that represents a decisive progress in all societies. In this paper, we present the analysis of several fragments of pottery dating from the Middle Ages and collected in the archaeological site of Gouraya in Béjaïa (Algeria). Energy-dispersive X-ray fluorescence measurements were performed to obtain the elemental composition of the clays and to attempt a classification of the samples through multivariate analysis methods, connecting them to the archaeological information about the sites. Hierarchical clusters analysis (HCA) identified two possible different groups, related to different production sites, even if only one source of clay seem to be used, consistently with the geological contest. Based on the results, a tentative provenance interpretation could be proposed on historical bases. We put in place a strategy that made it possible to perform provenance studies respecting sample integrity as we aim to extend our research also to integer and well-preserved object from museum, to create a database for Algerian production of in the Middle Ages. 相似文献