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排序方式: 共有386条查询结果,搜索用时 15 毫秒
381.
In this article a complete classification of tetravalent arc-transitive graphs of order twice a product of two primes is given. 相似文献
382.
383.
M. Ghasemi Kamalvand Kh. D. Ikramov 《Computational Mathematics and Mathematical Physics》2009,49(2):203-216
Minimal residual methods, such as MINRES and GMRES, are well-known iterative versions of direct procedures for reducing a matrix to special condensed forms. The method of reduction used in these procedures is a sequence of unitary similarity transformations, while the condensed form is a tridiagonal matrix (MINRES) or a Hessenberg matrix (GMRES). The algorithm CSYM proposed in the 1990s for solving systems with complex symmetric matrices was based on the tridiagonal reduction performed via unitary congruences rather than similarities. In this paper, we construct an extension of this algorithm to the entire class of conjugate-normal matrices. (Complex symmetric matrices are a part of this class.) Numerical results are presented. They show that, on many occasions, the proposed algorithm has a superior convergence rate compared to GMRES. 相似文献
384.
Natalia Dubrovina Lo?c O. Le Cunff N. Burokur R. Ghasemi A. Degiron A. De Lustrac A. Vial G. Lerondel A. Lupu 《Applied Physics A: Materials Science & Processing》2012,109(4):901-906
It is empirically shown by numerical modeling that a single metafilm formed by an array of cut wires on a silicon substrate behaves like a homogeneous layer for normal or oblique incidence. 相似文献
385.
In this project, the main aim is the design and present a novel and unique heterogeneous nanocatalyst based on a metal–organic framework/covalently sulfonated magnetic SBA-15 mesoporous silica composite with the emphasis on promoting clean and green synthetic transformations and increasing the catalytic properties. In more detail, initially, SBA-15 containing magnetic nanoparticles was functionalized by a 1,3-propane sultone ligand. In the next step, the functionalized mesoporous substrate was used as a scaffold for the growth and synthesis of the zeolite imidazolate framework-8 (ZIF-8) crystals. The obtained composite was further applied as a suitable support for the immobilization of Pd nanoparticles via a post-modification procedure and the generation of heterogeneous catalysts. The prepared Fe3O4@SBA-15-SO3H@ZIF-8@Pd was incorporated as a heterogeneous and green catalyst in the Suzuki coupling reaction in the natural deep eutectic solvent with efficient recyclability. 相似文献
386.
Forough Nasuhipur Zarrin Ghasemi Aziz Shahrisa Nasser Arsalani 《Journal of heterocyclic chemistry》2023,60(1):106-115
In this work, a one-pot three-component reaction of ninhydrin, primary amines, and 1,3-dicarbonyl compounds was investigated under various conditions to synthesis of diverse derivatives of dihydroindeno[1,2-b]pyrroles. Catalyst-free conditions in EtOH under ultrasound irradiation (45% of amplitude) were selected as a novel and efficient method for synthesis of these fused structures. The reactivity of different primary amines was then investigated for steric and electronic effects. Two examples of difunctional structures were also synthesized by using of 1,4-diaminobenzene under optimum conditions with high yields. The structure of all products was characterized by spectroscopic methods and elemental analysis. 相似文献