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1.
Nader G. Zamani 《Finite Elements in Analysis and Design》1987,3(4):333-340
The author reports on a numerical experimentation with the collocation finite element procedure using Hermite basis functions and the frontal elimination technique to solve some large-scale problems where up to 1000 linear equations are involved. Several test cases, including some applications to engineering problems, are presented. The implementation of the frontal technique applied to collocation is discussed to some extent. 相似文献
2.
It has come to our attention that this article, “Rheology, Morphology, and Estimation of the Interfacial Tension of Binary Blends Based on Low‐Density Polyethylene/Poly(trimethylene terephthalate) and High‐Density Polyethylene/Poly(trimethylene terephthalate)” by A. A. Shokri and S. E. Zamani was previously published under the title, “Rheology, Morphology and Estimation of Interfacial Tension of LDPE/EVA and HDPE/EVA Blends” by H. A. Khonakdar, S. H. Jafari, A. Yavari, A. Asadinezhad, U. Wagenknecht, in Polymer Bulletin 54, 75–84 (2005), . We have retracted the article, and offer our apologies to the authors of the original paper. 相似文献
3.
Axel Fischer Peter G. Jones Ion Neda Reinhard Schmutzler Igor V. Shevchenko 《无机化学与普通化学杂志》1994,620(5):908-913
Synthesis and Molecular Structure of new Ring Systems from 1,1,3,3-Tetrachloro-1,3-diphosphapropane 1,1,3,3-Tetrachloro-1,3-diphosphapropane 1 reacts in two different ways to form new heterocycles. Partial oxidation of 1 with tetrachloroorthobenzoquinone furnishes the methylene-bridged λ3P, λ5P species 3 . Subsequent reactions with di- and triethylamine lead to the condensed ring system 6 with the P?C bonds connected to a central four-membered ring. Compound 6 displays crystallographic inversion symmetry, a short transannular P? P distance and an extremely distorted tetrahedral coordination geometry at the four-membered ring phosphorus atoms. 1 reacts with 7 to give the heterocycle 8 with a central eight-membered ring involving four phosphorus atoms. The eight – membered ring shows a ?bent”? crown conformation, the condensed five – membered rings display envelope conformation. 相似文献
4.
Ion Neda Carsten Melnicky Alexander Vollbrecht Axel Fischer Peter G. Jones Reinhard Schmutzler 《无机化学与普通化学杂志》1996,622(6):1047-1059
The reaction of methylisatoic acid anhydride 1 with benzylamines led to the N-benzyl-N′-methylanthranilamide derivatives 2 – 4 . Their reaction with phosphorus trichloride furnished the 2-chloro-1-halobenzyl/benzyl-3-methyl-4(1 H)-1,3,2-benzodiazaphosphorin-4-ones 5 – 7 which, upon reaction with bis-(2-chloroethyl)ammonium chloride/triethylamine, were converted into the P-bis-(2-chloroethyl)amino-1-halobenzyl/benzyl-3-methyl-4(1 H)-1,3,2-benzodiazaphosphorin-4-ones 8 – 10 and 12 . With 2-chloroethylammonium chloride/triethyl-amine the P? NHCH2CH2Cl-substituted compound 11 was obtained from the PIIICl-species 6 . The reaction of 8 – 10 and 12 with hexafluoroacetone (HFA) took an unusual course: apart from the oxidative addition of HFA and formation of the perfluoropinacolyl ring system, one of the two CH2CH2Cl groups was found to alkylate the CH3N atom with formation of a five-membered (diazaphospholane) ring in the tricyclic phosphoranes 13 – 16 . The reaction of 11 with HFA also produced a spirophosphorane 17 which involved a λ5-oxazaphosphetidine ring system. In the reaction of 8, 10 and 12 with tetrachloro-o-benzoquinone, an oxidative addition reaction with concomitant N-alkylation and formation of the tricyclic phosphoranes 18 – 20 was found to take place. Single crystal X-ray structure determinations are described for the phosphoranes 13, 14 and 16 , and for the precursor compound 9 . The following features are common to the isostructural compounds 13 and 16 and the diethyl ether hemisolvate of 14 : the (λ5)-spiro phosphorus atom lies out of the plane of the other atoms of the rings to which it is common, and the dioxaphospholane rings display a twist conformation. In the λ3P-compound 9 the phosphorus atom also lies out of the plane of the other ring atoms. 相似文献
5.
Some new N‐glycosides of 4‐(2‐phenylethyl)‐5‐pyridyl‐1,2,4‐triazole‐3‐thiones were synthesised by the coupling reaction of halo sugar with 4,5‐disubstituted 3H‐1,2,4‐triazole‐3‐thiones in the presence of mercuric cyanide and dry nitromethane as solvent, followed by deprotection using dry ammonia in methanol. All of the above compounds were fully characterized by means of infrared, 1H NMR spectroscopy, mass spectroscopy and elemental analysis. 相似文献
6.
A variety of alcoholic TBDMS (t-butyldimethylsilyl) ethers are easily removed in excellent yields by treatment with a catalytic amount of N-iodosuccinimide (NIS, 5 mol %) in methanol. This method is able to deprotect TBDMS ethers of alcohols in the presence of TBDMS ethers of phenols. 相似文献
7.
Sai Kumar Chakka Zamani E.D. Cele Sphelele C. Sosibo Vivian Francis Per I. Arvidsson Hendrik G. Kruger Glenn E.M. Maguire Thavendran Govender 《Tetrahedron: Asymmetry》2012,23(8):616-622
A series of novel TIQ based N,N′-oxide ligands were synthesised and screened for their catalytic activity in the enantioselective conjugate addition of thioglycolate to chalcones. Bulky groups on the side chain of the TIQ backbone provided the highest enantioselectivity of up to 88% with 10 mol % catalyst loading. It was also observed that these reactions proceeded optimally in the presence of dichloromethane as a solvent. Screening of various metals emphasized La(OTf)3 as the ideal pre-catalyst for this particular reaction. 相似文献
8.
An environmentally benign aqueous protocol for the synthesis of 3,4-dihydropyrimidin-2-(1H)-ones and thiones promoted by a green catalyst,silica gel-supported L-pyrrolidine-2-carboxylic acid-4-hydrogen sulfate,has been developed.The use of nontoxic,thermally stable and inexpensive amino acid catalyst makes the process simple with minimal amount of chemical waste.Compared with classical Biginelli reaction conditions,this new method has the advantages of high yields and simple workup procedures. 相似文献
9.
10.
Structural Chemistry - In this study, density functional theory (DFT) was employed to predict thermochemical and energetic properties for single-walled carbon nanotubes (SWCNTs) decorated with one... 相似文献