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排序方式: 共有86条查询结果,搜索用时 15 毫秒
31.
32.
We characterize Banach lattices on which each positive Dunford-Pettis operator is AM-compact and we give some consequences. 相似文献
33.
Abdessamade Benahmed Khalil Azzaoui Abderahmane El Idrissi Hammouti Belkheir Said Omar Said Hassane Rachid Touzani Larbi Rhazi 《Molecules (Basel, Switzerland)》2022,27(4)
The need for biodegradable and biocompatible polymers is growing quickly, particularly in the biomedical and environmental industries. Cellulose acetate, a natural polysaccharide, can be taken from plants and modified with polycaprolactone to improve its characteristics for a number of uses, including biomedical applications and food packaging. Cellulose acetate-g-polycaprolactone was prepared by a three-step reaction: First, polymerization of ε-caprolactone via ring-opening polymerization (ROP) reaction using 2-hydroxyethyl methacrylate (HEMA) and functionalization of polycaprolactone(PCL) by introducing NCO on the hydroxyl end of the HEMA-PCL using hexamethyl lenediisocyanate(HDI) were carried out. Then, the NCO–HEMA-PCL was grafted onto cellulose acetate (using the “grafting to” method). The polycaprolactone grafted cellulose acetate was confirmed by FTIR, the thermal characteristics of the copolymers were investigated by DSC and TGA, and the hydrophobicity was analyzed via water CA measurement. Introducing NCO-PCL to cellulose acetate increased the thermal stability. The contact angle of the unreacted PCL was higher than that of cellulose acetate-g-PCL, and it increased when the chain length increased. The CA-g-PCL50, CA-g-PCL100, and CA-g-PCL200 showed very high inhibition zones for all three bacteria tested (E. coli, S. aureus, and P. aeruginosa). 相似文献
34.
We introduce and study new class of sets (almost L-limited sets). Also, we introduce new concept of property in Banach lattice (almost Gelfand–Phillips property) and we characterize this property using almost L-limited sets. On the other hand, we introduce the class of disjoint limited completely continuous operators which is a largest class than that of limited completely continuous operators, we characterize this class of operators and we study some of its properties. 相似文献
35.
Badia Ait Allal Larbi El Firdoussi Smail Allaoud Abdallah Karim Yves Castanet Andr Mortreux 《Journal of molecular catalysis. A, Chemical》2003,200(1-2):177-184
The allylic oxidation of α-pinene 1 was investigated using various catalytic systems. By a proper choice of the latter, the reaction can be directed toward the selective synthesis of verbenol 2 or verbenone 3. High yield into verbenone was achieved under mild conditions with copper salts as catalysts and t-butyl hydroperoxide (TBHP) as oxidant. On the other hand, when Pd(acac)2 was used with hydrogen peroxide, verbenol was obtained as the main product. 相似文献
36.
Ara Irene El Bahij Fatima Lachkar Mohamed Ben Larbi Najib 《Transition Metal Chemistry》2003,28(8):908-912
Monomeric, five-coordinated bis(ethylxanthato)ZnII(phosphine) complexes [phosphine = PPh3, P(o-tolyl)3, P(CH2Ph)3] have been synthesized by addition of the phosphine ligand (1:1 molar ratio) to CH2Cl2 solutions of [Zn(S2COEt)2]. Bidentate ligands Ph2PCH2CH2PPh2 (dppe) and Ph2P(CH2)4PPh2 (dppb) reacted in a 1:2 molar ratio to form dinuclear phosphine-bridged complexes. The Zn—P bonds are very labile and are probably broken in solution. The characterization of all the compounds has been carried out by elemental analyses and spectroscopic methods (i.r. and n.m.r.). The structure of binuclear [(S2COEt)2Zn(-dppb)Zn(S2COEt)2], determined by X-ray crystallography, shows a distorted trigonal bipyramidal environment for the Zn atoms, formed by two chelating xanthate and a bridging dppb ligand. 相似文献
37.
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.
相似文献
38.
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40.
Djamel Tahtat Mohamed Mahlous Samah Benamer Assia Nacer Khodja Souad Larbi Youcef 《Radiation Physics and Chemistry》2012,81(6):659-665
Chitosan A1, A2 and A3 with molecular weight of 471, 207 and 100 kDa respectively, produced from squid pen chitin was degraded by gamma rays in the solid state and in aqueous solution with various doses in air at ambient temperature. Effect of molecular weight on radiation chemical degradation yield of chain scission and degradation rate constants of γ-irradiated chitosan in solid state and in aqueous solution was investigated. The radiation chemical degradation yield G(s) and degradation rate values were calculated. The molecular weight changes were monitored by capillary viscometry method and the chemical structure changes were followed by UV analysis. The results showed that, the degradation of chitosan was faster in solution, than in solid state. The values of G(s) in solid state and in aqueous solution were respectively 1.1×10?8 mol/J and 0.074×10?7 mol/J for A1, 4.42×10?8 mol/J and 0.28×10?7 mol/J for A2 and 6.08×10?8 mol/J and 0.38×10?7 mol/J for A3. Degradation rate constants values ranged from 0.41×10?5 to 2.1×10?5 kGy?1 in solid state, whereas in solution they ranged from 13×10?5 to 68×10?5 kGy?1. The chitosan A3 was more sensitive to radiolysis than A1 and A2. The chain scission yield, G(s) and degradation rate constants seems to be greatly influenced by the initial molecular weight of the chitosan. Structural changes in irradiated chitosan are revealed by the apparition of absorption peaks at 261 and 295 nm, which could be attributed to the formation of carbonyl groups. In both conditions the peak intensity was higher in chitosan A3 than in A1 and A2, the oxidative products decreased with increasing molecular weight of chitosan. 相似文献