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排序方式: 共有183条查询结果,搜索用时 46 毫秒
41.
Michel Boulouard Sylvain Rault Patrick Dallemagne Abdellah Alsaïdi Max Robba 《Journal of heterocyclic chemistry》1996,33(1):87-91
Treatment of 2-(2-formyl-1H-pyrrol-1-yl)-3-thiophenecarbonitrile by sodium percarbonate afforded, in a one-pot sequence and on a multigram scale, 5,6-dihydro-6-hydroxy-4H-pyrrolo[1,2-a]thieno-[3,2-f][1,4]diazepin-4-one whose reactivity towards various nucleophiles like amines, hydrazines and thiols was evaluated. 相似文献
42.
Abdellah Ech-Chahad 《Tetrahedron letters》2005,46(31):5113-5115
Capitalizing on in situ activation with the cyclic phosphonic anhydride PPAA (1), the conversion of carboxylic acids into hydroxamic acids has been reduced to an experimentally simple one-pot operation that addresses the issue of polyacylation without resorting to a large excess of hydroxylamine or to protection. Scope and selectivity were satisfactory with a wide range of substrates, including α,β-unsaturated acids and hydroxyacids. 相似文献
43.
The Douglas–Peaceman–Rachford–Varga operator splitting methods (DPRV methods) are attractive methods for monotone variational
inequalities. He et al. [Numer. Math. 94, 715–737 (2003)] proposed an inexact self-adaptive operator splitting method based on DPRV. This paper relaxes the inexactness
restriction further. And numerical experiments indicate the improvement of this relaxation.
相似文献
44.
Starting from thiacalixarene tetraacetates, tetraacetohydrazides have been prepared and then used for the introduction of semicarbazide and thiosemicarbazide fragments into the lower rim by the reaction with phenyl isocyanate and phenyl isothiocyanate in dry toluene. The structures of the prepared compounds were investigated by FT‐IR, FAB‐MS, 1H NMR, and X‐ray crystallography, and their receptor properties were examined by liquid liquid extraction of dichromate anions. 相似文献
45.
Abdellah Bnouhachem 《高等学校计算数学学报(英文版)》2006,15(1):74-81
Recently,a class of logarithmic-quadratic proximal(LQP)methods was intro- duced by Auslender,Teboulle and Ben-Tiba.The inexact versions of these methods solve the sub-problems in each iteration approximately.In this paper,we present a practical inexactness criterion for the inexact version of these methods. 相似文献
46.
Abdellah Zeroual Mar Ríos-Gutiérrez Mohammed El Idrissi Habib El Alaoui El Abdallaoui Luis R. Domingo 《International journal of quantum chemistry》2019,119(18):e25980
The [3+2] cycloaddition (32CA) reaction of tomentosin with benzonitrile oxide yielding a spiro-isoxazoline has been studied within the Molecular Electron Density Theory at the B3LYP/6-31(d,p) computational level. Given the multifunctionality of tomentosin, this 32CA reaction can take place along 16 competitive reaction paths. The chemo-, regio-, and stereoisomeric reaction paths involving the two C C double bonds of tomentosin have been studied. Density functional theory (DFT) calculations account for the total chemo- and regioselectivity, in complete agreement with the experimental outcomes, being suggestive of low diastereofacial selectivity. Analysis of the conceptual DFT indices accounts for the nonpolar character of this 32CA reaction. On the other hand, the topological analysis of the electron localization function of the selected points of the intrinsic reaction coordinate associated with the formation of the C C and C O single bonds emphasizes the zw-type reactivity of the phenyl nitrile oxide; the reaction taking place through a non-concerted two-stage one-step mechanism initialized with the formation of the C C single bond involving the β-conjugated carbon of tomentosin. 相似文献
47.
T. Tahri S. A. Abdul-Wahab A. Bettahar M. Douani H. Al-Hinai Y. Al-Mulla 《Journal of Thermal Analysis and Calorimetry》2009,96(1):35-42
A theoretical model is developed in Part I of this study to simulate the physical process of condensation of the humid air
in the condenser of an existing seawater greenhouse that is located in Muscat, Oman. Application is conducted in this part
to validate the theoretical developments. Comparisons are made between the predictions and the existing experimental results.
The results indicate that the comparison is well consistent. The effect of the relative humidity, the dry bulb temperature
and the solar radiation are also discussed to see their effects on the condensate values. 相似文献
48.
49.
The synthesis of photocrosslinkable polysiloxanes containing gem di-oxaalkylene styrenyl groups and gem di-urethane-α-methyl styrenyl groups has been performed by copolycondensation of α,ω-dihydroxy polydimethyl siloxanes and dichlorosilanes bearing either cyclic acetal groups or Si-H groups (onto which the cyclic acetal groups are further added) and dichlorosilanes bearing alkyl groups. The introduction of styrenyl groups was then achieved by hydrolysis of the acetal groups into the corresponding alcohols followed by reaction with chloromethyl styrene or with 3-isopropenyl-α,α- dimethylbenzyl isocyanate.The structure of the different products synthesized was determined by IR, 1H, 13C and 29Si NMR spectroscopies. The thermal properties of the polysiloxanes bearing gem di-styrenyl groups have been studied at low and high temperatures.These products have been crosslinked under UV, in the presence of a cationic photoinitiator, and showed very good release paper properties. 相似文献
50.