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91.
Wafaa M. Abdou Ashraf A. Sediek Maha D. Khidre 《Monatshefte für Chemie / Chemical Monthly》2008,139(6):617-623
Treatment of triketoindan-2-oxime with α-phosphonyl carbanions in sodium ethanolate solution at reflux temperature led to
a number of the corresponding substituted spiroisooxazole-, fused 1,3-oxazole, and 1,4-oxazine phosphor esters in moderate
to high yields. Mechanisms for the formation of five- and six-membered rings are provided. A comparison of Wittig-Horner and Wittig reagent counterparts in reactions with the oxime is discussed. The various biological properties of selected examples of
the synthesized products were studied.
Correspondence: Wafaa M. Abdou, Chemical Industries Division, National Research Center, Elbohouth St., D-12622 Dokki, Cairo,
Egypt. 相似文献
92.
Babacar Toumbou Daniel Y. Le Roux Abdou Sène 《Journal of Differential Equations》2008,244(8):2020-2040
We present an existence theorem of a two-dimensional sedimentation model coupling a shallow water system with a sediment transport equation. The shallow water system includes Coriolis and friction terms. A Galerkin method is used to obtain a finite-dimensional problem which is solved using a Brouwer fixed point theorem. We prove that the limits of the resulting solution sequences satisfy the model equations. 相似文献
93.
Amita Gupta Alexei Yu Ganin Parmanand Sharma Vikrant Agnihotri LM Belova KV Rao Mikhail E Kozlov AA Zakhidov RH Baughman 《Pramana》2002,58(5-6):1051-1059
We present studies of novel nanocomposites of BiNi impregnated into the structure of opals as well as inverse opals. Atomic force microscopy and high resolution elemental analyses show
a highly ordered structure and uniform distribution of the BiNi filler in the matrix. These BiNi-based nanocomposites are
found to exhibit distinct ferromagnetic-like ordering with transition temperature of about 675 K. As far as we know there
exists no report in literature on any BiNi compound which is magnetic. 相似文献
94.
Hydrochloric acid solutions (0.05–1.18m) containing p-nitroaniline (8×10–5M) as indicator base have H
o
values which increase with increase of ethylene carbonate (EC) content in the solvent mixture for a fixed molality of the acid. This behavior confirms similar results obtained in AN-H2O, MCS-H2O, DMSO-H2O and NMF-H2O systems. This trend indicates that the solvent basicity increases by successive addition of the organic solvent. The partition of the proton between water and EC has been calculated using Sadek's theory. It is clear that [H3O+] decreases gradually with increase of EC content. The change in the dissociation constant of p-nitroanilinium ion,
decreases sharply with increasing dielectric constant. The free energy change of transfer, G
t
o
, has been attributed to an electrostatic, G
t(el)
o
, and a nonelectrostatic, electrostatic, G
t(non)
o
component. It has been found that G
t(non)
o
is negative. 相似文献
95.
Hanan E. Abdou Ahmed A. Mohamed José M. López-de-Luzuriaga John P. FacklerJr. 《Journal of Cluster Science》2004,15(4):397-411
The syntheses and characterization of gold(I) naphthyl, pentafluorophenyl, and trifluoromethylphenyl amidinate complexes are reported. The tetranuclear clusters are obtained from the reaction of Au(tetrahydrothiophene)Cl with the potassium salt of the corresponding amidinate in a THF solvent. The crystal structures of the gold(I) naphthyl, 2, and pentafluorophenyl, 3, amidinates show a short Au···Au distance of ~3. 0 Å typical of compounds having an aurophilic interaction. The gold atoms are arranged in a square (Au···Au···Au = 87°–92°) in the pentafluorophenyl derivative and in a parallelogram (Au···Au···Au = 68°–110°) in the naphthyl amidinate complexes. The naphthyl and trifluoromethylphenyl complexes are visibly luminescent in the solid state at liquid nitrogen temperature displaying asymmetric emission bands at 538 and 473 nm, respectively. The luminescent lifetimes of these species are in the millisecond range indicating phosphorescent processes. 相似文献
96.
Abdou Youssef 《PAMM》2007,7(1):1010501-1010502
As digital libraries of mathematical and scientific contents become available, it is essential to have math-aware search systems. The search systems must understand math symbols and structures, and allow users to enter queries that involve not only text keywords but also mathematical expressions and fragments of expressions. In addition, the search results must be presented in a way that enables the user to find the desired information rapidly. This short paper gives a quick overview of the state of the art of math search, and focuses on the math search system that the author has developed for the Digital Library of Mathematical Functions (DLMF) project of the National Institute of Standards and Technology. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
97.
H. A. Shaban A. A. Shaltout M. Abdou E. A. Al Ashker M. Elgohary 《Journal of Applied Spectroscopy》2011,77(6):771-777
Cu, Zn, and Se were successfully determined in a few microliters (<100 μl) of biological samples using discrete injection
atomic absorption spectrometry. Different factors were investigated in order to obtain a biological sample volume which is
valid for analysis. Among them are the effect of microsampling volume variations (starting from 40 to 200 μl), nebulization
efficiency, detection limits, precision, and finally the calibration and sensitivity of the proposed method. It was found
that 60 μl of the biological sample was adequate for the quantitative analysis with reasonable precision. The advantages of
the proposed method are not only rapidity, simplicity, sensitivity, and good precision, but also, contrary to conventional
flame atomic absorption spectrometry, the capability of analyzing microvolumes of samples. 相似文献
98.
Joseph M. Abdou 《International Journal of Game Theory》2012,41(4):775-789
We study the stability and the stability index of the meet game form defined on a meet semilattice. Given any active coalition structure, we show that the stability index relative to the equilibrium, to the beta core and to the exact core is a function of the Nakamura number, the depth of the semilattice and its gap function. 相似文献
99.
100.
Ashraf A. Sediek Abeer A. Shaddy Wafaa M. Abdou 《Journal of heterocyclic chemistry》2011,48(6):1258-1263
A new and efficient conjugate addition of trimethyl and triethyl phosphites to 3‐ω‐azidoacetylcoumarin ( 1 ) has been studied. The reaction proceeded smoothly at r.t. furnishing 1,2,3,4‐triazaphosphole coumarin derivatives 4a , 4b in ~75% yields. Linear substituted triazoles 10b , 11a were also obtained from the reactions of 1 with α‐keto ylides, acetyl‐ and benzoylmethylene triphenylphosphoranes. Contrary to these results, Wittig reaction was occurred when 1 was allowed to react with α‐alkoxycarbonylmethylene‐ and cyanomethylenetriphenylphosphoranes 7c , 7d , 7e as well as with methylidene‐ and benzylidenetriphenylphosphoranes 8b , 10a resulting in the formation of the corresponding olefins either as an intermediate 14b or as final products 11b , 11c , 12a . J. Heterocyclic Chem., (2011). 相似文献