排序方式: 共有97条查询结果,搜索用时 168 毫秒
31.
Corma A García H Moussaif A Sabater MJ Zniber R Redouane A 《Chemical communications (Cambridge, England)》2002,(10):1058-1059
Two solid catalysts in which a chiral copper(II) bisoxazoline has been covalently anchored on silica and MCM-41 have been prepared; the solids are enantioselective catalysts (up to 92% ee) for the Friedel-Crafts hydroxyalkylation of 1,3-dimethoxybenzene with 3,3,3-trifluoropyruvate. 相似文献
32.
Redouane Khaoulaf Mustapha Ezzaafrani Abdelaziz Ennaciri Mohammed Harcharras Francesco Capitelli 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):1367-1376
Abstract Infrared and Raman spectra of dipotassium zinc bis(dihydrogendiphosphate) dihydrate, K2Zn(H2P2O7)2 .2H2O have been collected and interpreted using factor group analysis. Noncoincidence of the Raman and infrared spectra bands confirms a centrosymmetric structure for K2Zn(H2P2O7)2 .2H2O previously investigated by X-ray structural study, as well as the joint appearance of νas POP and νs POP point to a bent POP configuration. 相似文献
33.
J. Sayyad AminE.Nikooee M.H. GhateeSh. Ayatollahi A. AlamdariT. Sedghamiz 《Applied Surface Science》2011,257(20):8341-8349
This paper aims at investigation of the effect of asphaltene structure on wettability and topography alteration of a glass surface as a result of asphaltene precipitation. In order to provide a better insight into the topography alteration, a bi-fractal approach was employed. Such an approach is capable of discriminating topography alteration in two different surface types, namely, macro-asperities and micro-asperities. The observed variation of the fractal dimension in the two surface types could be considered as the consequence of different asphaltene sources. Therefore, the structure of different asphaltene sources was carefully examined. The effect of asphaltene structure is more pronounced for asphaltene precipitation at higher pressure. It was revealed that asphaltene particles of high complexity and with larger poly-aromatic rings tend to be detached easier at higher pressure than those with smaller poly-aromatic rings. Another evidence to emphasize the significance of asphaltene structure was given through wettability alteration. It was found that asphaltene particles with larger poly-aromatic rings turn the surface less oil wet at higher pressure. It seems that the difference in wetting condition and surface topography alteration of different asphaltene sources roots in their different structures. 相似文献
34.
Ferouani Ghaniya Ameur Nawal Bachir Redouane 《Research on Chemical Intermediates》2020,46(2):1373-1387
Research on Chemical Intermediates - Bimetallic gold–iron catalysts supported on ZrO2 and TiO2 were prepared by under potential deposition. The characterization of the catalysts was performed... 相似文献
35.
Toumieux S Beniazza R Desvergnes V Aráoz R Molgó J Landais Y 《Organic & biomolecular chemistry》2011,9(10):3726-3732
A straightforward access to the C10-C20 skeleton of gymnodimine, incorporating a tetrahydrofuran fragment, is described. The elaboration of the THF moiety is based on a stereocontrolled Ueno-Stork cyclization. A Lewis-acid mediated allylation of the resulting acetal at C13 and a Horner-Wadsworth-Emmons olefination on the ketone at C17 complete the synthesis. 相似文献
36.
Aissou K Otsuka I Rochas C Fort S Halila S Borsali R 《Langmuir : the ACS journal of surfaces and colloids》2011,27(7):4098-4103
This paper discusses the self-assembly of rod-coil amylose-b-polystyrene (Mal-b-PS) block copolymer thick and thin films. The nano-organization falls in an interdomain spacing d of about 10 nm, much smaller than flexible-flexible petrol block copolymer systems. Additionally, hydrogen-bonding interactions between carbohydrate rods (amylose) and 4',4-bipyridine (bipy) molecules induces phase transitions. Indeed, adding bipy in maltooctadecaose-block-polystyrene (Mal18-b-PS) copolymers results, at room temperature, in the formation of a lamellar phase having Mal18 bipy-rich nanodomains instead of hexagonal close-packed (HCP) of cylinders made of Mal18, whereas a coexistence of Mal7bipy-rich cylindrical and spherical nanodomains are formed from maltoheptaose-b-polystyrene (Mal7-b-PS) copolymers instead of a poorly organized array of Mal7-based cylinders. On heating, the Mal7bipy-b-PS system shows more rich phase behavior as compared to the Mal7-b-PS one due to weakening of hydrogen bonding with temperature. Such a system is of great interest in developing active layers in light-emitting diodes (LEDs) or in photovoltaic cells to realize devices with an optimal structure, that is, having large interface area and domain size with similar exciton diffusion length (10 nm). 相似文献
37.
Jean-François le Meins Clément Houg Redouane Borsali Daniel Taton Yves Gnanou 《Macromolecular Symposia》2009,281(1):113-118
Summary: In this work we discuss the self-assembling behaviour in solution of a block copolymer, dextran-block-polystyrene, in the presence of homopolystyrene (PS) which allows to decrease the hydrophilic fraction f of the mixture. Dynamic and static light scattering experiments have been carried out in water-miscible solvents (DMSO and THF) to probe the formation of supramolecular structures. Results have been compared to those obtained with a block copolymer solution having the same hydrophilic fraction f. Interestingly, the morphology of the self-assembled structures was the same for a given value of f. 相似文献
38.
Summary: Dynamic light scattering (DLS) and fluorescence experiments were carried out to study PCL44-b-PEO114 biocompatible micelles used as nanocarriers in drug delivery. Micelles prepared by a simple procedure (THF removal under nitrogen flow) exhibited a narrow size distribution with an average diameter of 100 nm. For micelles containing a hydrophobic model compound (pyrene) within the PCL core, a smaller average micellar size of 80 nm was observed, with a simultaneous broadening in the size distribution profile. In parallel to DLS results, fluorescence experiments showed evidence of pyrene encapsulation, and that the onset of the micellization process occurs at approximately 10/90 (v/v) THF/water mixtures in the case of PCL44-b-PEO114 polymer. 相似文献
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40.
Redouane Kara Jean Jacques Loiseau Said Djennoune 《Nonlinear Analysis: Hybrid Systems》2008,2(4):1010-1020
This paper deals with the computation of the asymptotic firing rate vector and the stationary marking of continuous weighted marked graphs under infinite servers semantics. The continuous weighted marked graphs are a particular class of continuous Petri net where each place has exactly one input and one output transition. First, we give an explicit formula to compute the asymptotic firing rate vector of transitions using the structure of the given net. Then, under the assumption that there exists only one critical circuit in the strongly connected continuous neutral weighted marked graphs, an original approach to compute the vector of stationary marking is presented. Finally, an application to a flexible manufacturing system is given. 相似文献