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91.
92.
反相微乳液合成30~100nm磁性聚合物纳米微球 总被引:12,自引:0,他引:12
利用反相微乳液一步法成功地制备了磁性聚合物纳米微球,微球粒径在30~100nm左右,均一性较好,研究表明,Fe(Ⅱ)浓度对微乳液和微胶乳的稳定性有很大影响,碱的种类、AOT和单体的含量能控制微球粒径,用振动探针式磁强仪(VSM)测定了不同比例的[Fe(Ⅱ)]/[Fe(Ⅲ)]所合成的聚合物微球的磁性,发现温度对合成高磁饱和强度和超顺磁性起关键作用,合成的磁性聚合物微胶乳透明且稳定性较好. 相似文献
93.
Abdelhamid Meziani 《Journal of Differential Equations》2007,239(1):16-37
For any given n∈Z+ and k∈Z+, infinitesimal bendings of order n and of class Ck are constructed for a class of surfaces in R3. These surfaces are given as graphs of homogeneous polynomials P(x,y) and they have positive curvature except at the origin. 相似文献
94.
Abdelhamid Bourass Bouchaib Ferrahi Bertram M. Schreiber Maria Victoria Velasco 《Set-Valued Analysis》2005,13(2):105-124
We present a generalization of the Uniform Boundedness Principle valid for random multivalued linear operators, i.e., multivalued linear operators taking values in the space L0(,Y) of random variables defined on a probability space
with values in the Banach space Y. Namely, for a family of such operators that are continuous with positive probability, if the family is pointwise bounded with probability at least >0, then the operators are uniformly bounded with a probability that in each case can be estimated in terms of and the index of continuity of the operator. To achieve this result, we develop the fundamental theory of multivalued linear operators on general topological vector spaces. In particular, we exhibit versions of the Closed Graph Theorem, the Open Mapping Theorem, and the Uniform Boundedness Principle for multivalued operators between F-spaces.Mathematics Subject Classifications (2000) 46A16, 46A30, 47A06, 47B80, 60H25. 相似文献
95.
Coraline Sester Fabrice Ofridam Noureddine Lebaz Emilie Gagnire Denis Mangin Abdelhamid Elaissari 《先进技术聚合物》2020,31(3):440-450
Poly (methyl methacrylate) derivatives such as Eudragit are largely used for drug encapsulation and in controlled oral drug delivery. With special focusing on those applications, solubilization and precipitation conditions of two pH‐sensitive Eudragit polymers, namely, L100 and E100, were investigated via systematic studies. Effects of various physicochemical parameters such as pH, polymer concentration, salinity, buffer concentration, and incubation time on the solubilization and precipitation of these polymers were investigated. In addition, pH titration of both polymers was reported. Considering both macroscopic and quantitative aspects such as the final mean particle size, size distribution, morphology, and the zeta potential, it was established that the different precited parameters could not be dissociated and exert a synergic action on the solubilization and precipitation of both polymers. Titration curves revealed two equivalences that helped estimating carboxylic content of Eudragit L100 (6 mmol/g) and ammonium content of Eudragit E100 (4 mmol/g). In this study, the solubilization and the precipitation domains were for the first time clearly established by considering the above‐mentioned parameters. Moreover, it was found that Eudragit L100 and E100 cannot be considered as classic polyelectrolytes; in fact, solubilization and precipitation domains were not affected by ionic strength. 相似文献
96.
97.
Nesma A. Abd El-Fatah Ahmed F. Darweesh Adel A. Mohamed Ismail A. Abdelhamid Ahmed H.M. Elwahy 《Tetrahedron》2017,73(11):1436-1450
The synthetic utility of 2-mercaptonicotinonitriles 3 and 4, as well as 2-mercapto-4-oxo-6-phenyl-1,4-dihydropyrimidine-5-carbonitrile 20 as building blocks for novel bis- and poly(pyridines), along with poly(pyrimidines) via alkylation with the corresponding bis- and poy(halo) compounds was investigated. Spectroscopic and theoretical studies confirmed the S-alkylation rather than the N-alkylation. 相似文献
98.
Saleh M. Al-Mousawi Moustafa Sherief Moustafa Ismail Abdelshafy Abdelhamid Mohamed Hilmy Elnagdi 《Tetrahedron letters》2011,52(2):202-204
The condensation of α-keto α′-formylarylhydrazones with ethyl cyanoacetate afforded ethyl 5-arylazo-2-hydroxy-6-aryl (or alkyl) nicotinates. The structures of the reaction products could be established based on X-ray crystal structure determination. 相似文献
99.
Samir Chakhari Mohamed Kadri Younes Alain Rives Abdelhamid Ghorbel 《Journal of Sol-Gel Science and Technology》2014,69(2):378-385
Zirconia doped by heteropolytungstic acid HPW have been synthesized by sol–gel method using two drying techniques of the solvent evacuation. Samples were analyzed with adsorption–desorption of N2 at 77 K, and the aerogel catalyst was found to exhibit a higher surface area and a higher average pore diameter compared to xerogel. XRD results show that aerogel develops ZrO2 tetragonal phase, whereas xerogel is amorphous. The thermal analysis studies show that the aerogel’s thermal stability is better than the xerogel one. The catalytic behavior of the aerogel and xerogel toward the nature of the isomerization products probably depends on the acidity and the presence of carbide species. This has been explained by XPS and isopropanol dehydration reaction. In fact, the deconvolution aerogel’s Cls bands reveals the presence of four carbon species assigned to C–C, C=O, C–O and carbide species. 相似文献
100.
Experimental Techniques - 相似文献