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排序方式: 共有174条查询结果,搜索用时 743 毫秒
1.
Abdelkrim Chakib Touria Ghemires Abdeljalil Nachaoui 《Mathematical Methods in the Applied Sciences》2002,25(6):473-489
In this paper, the flow problem of incompressible liquid through an inhomogeneous porous medium (say dam), with permeability allowing parametrization of the free boundary by a graph of continuous unidimensional function, is considered. We propose a new formulation on an optimal shape design problem. We show the existence of a solution of the optimal shape design problem. The finite element method is used to obtain numerical results which show the efficiency of the proposed approach. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
2.
A rigid terpyridine ligand containing chiral alkyl chains has been synthesized, characterized and subsequently complexed with ruthenium(II) ions. The product was characterized by MALDI-TOF-MS, UV-vis and NMR. Circular dichroism showed the appearance of extended helical columnar aggregates. 相似文献
3.
Abdelkrim El‐Ghayoury Albertus P. H. J. Schenning E. W. Meijer 《Journal of polymer science. Part A, Polymer chemistry》2002,40(22):4020-4023
An oligo(p‐phenylene vinylene) that contains terpyridine ligands has been synthesized. Upon addition of metal ions, a π‐conjugated metallo polymer is formed in which the well‐defined character of oligomers and the material properties of polymers are combined. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4020–4023, 2002 相似文献
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5.
Hanifa Daoui Yasmine Bouhamidi Ahmed Boucherit Mohamed Zouikri 《International Journal of Polymer Analysis and Characterization》2018,23(5):463-473
The fundamental understanding of the behavior of a solid is intimately related to the understanding of the interactions on the surface of the latter, a major challenge in particular if the material is natural and ecological. The infinite dilution-inverse gas chromatography was used to evaluate the surface thermodynamic properties of several phases (grafted and/or coated) diatomite. A series of non- or polar-solute probes were injected at temperatures of 45?°C and 90?°C. The dispersive surface free energies values of the supports decrease with increasing temperature and their active surface is amphoteric with predominantly acidic character. 相似文献
6.
1,4-Diacetylpiperazine-2,5-dione (1) was condensated with aldehydes (2) with KF on alumina without solvent under microwaves or in at room temperature in the presence of DMF. The reaction was stereoselective and some natural products (4a-c) like albonursin(4c) were synthesized. 相似文献
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8.
Smaail Radi Ahmed Attayibat Abdelkrim Ramdani Maryse Bacquet 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):232-241
The immobilization of a thiophene-based tripodal ligand, with a donor sulfur, on the surface of an epoxide group containing a silica gel phase for the synthesis of a newly functionalized material based on porous silica-bound bi-thiophene tripodal ligand (SGBT) is described. The modified silica surface was characterized by 13C NMR of a solid sample, elemental analysis, and infrared spectra. This new material was also studied and evaluated by determination of the surface area using the BET equation, the adsorption and desorption capability using the isotherm of nitrogen and BJH pore sizes, respectively. The target material exhibits good thermal stability as determined by thermogravimetry curves. The synthesized material was utilized in column and batch methods for adsorption of Hg2+, Cd2+, Pb2+, Cu2+, Zn2+, K+, Na+, and Li+, and the material exhibits an affinity only towards toxic heavy metals. 相似文献
9.
Amel Zitouni Abdelkrim Gouasmia Sabrina Bouguessa Lakhémici Kaboub Louiza Boudiba 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):1744-1754
A new series of tetrathiafulvalene (TTF) molecules with extended π-system was prepared by using a Wittig reaction to generate the TTF key. The process of deprotection-alkylation of thiolates provided access to a wide variety of molecules. The study of their reducing power was carried out by cyclic voltammetry. Charge transfer complexes have also been chemically prepared by using TCNQ as an electron acceptor; the electrical conductivity of their compressed powders shows insulator behavior. The IR spectra of the TCNQ salts were recorded and used to characterize and estimate the degree of charge transfer of these complexes. GRAPHICAL ABSTRACT 相似文献
10.
Abdelkrim Azzouz Vasilica-Alisa Aruş Nicoleta Platon Kamel Ghomari Ieana-Denisa Nistor Tze Chieh Shiao René Roy 《Adsorption》2013,19(5):909-918
Dendrimers bearing hydroxyl groups supported by layered double hydroxides (CO3–LDH) with Mg/Al ratio ranging from 1:1 to 5:1 showed improved properties for the reversible capture of carbon dioxide (CO2). The adsorption capacity of the starting LDH was due to the intrinsic base-like behavior, and was found to depend on the Mg/Al ratio. When contacted with polyol dendrimers in aqueous media, no intercalation took place. This was explained in terms of low exfoliation grade of LDH and hydrophobic character of the dendrimer molecules. The latter rather adsorb on the external surface of the LDH stacks for low dendrimer loadings, or aggregate into organic clusters for higher contents. Analyses through thermal programmed desorption of CO2 revealed that dendrimer incorporation advantageously attenuates the basicity strength of the starting LDH support, by lowering the desorption temperature. The OH groups of the organic moiety were found to display an amphoteric character, and act as the main adsorption sites. The weak interactions with CO2 facilitate easier release of the major part of adsorbed CO2 at temperature not exceeding 80–100 °C. On polyol organo-LDHs, the reversible CO2 retention was discussed herein in terms of acid–base interactions. This concept allows envisaging the capture of diverse pollutants and other greenhouse gases by modifying the chemical groups on the dendritic moiety. 相似文献