排序方式: 共有142条查询结果,搜索用时 0 毫秒
31.
32.
Saiid Dehghanpour-farashah Amir H. Mahmoudkhani Abbas Eslami Khodayar Gholivand 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1)
Abstract In 13 NMR study organophosphorus compounds, sign and magnitude of 13 C-31 P spin-spin couplings has been of great interest to elucidate stereochemistry and electronic state of phosphorus central atom. However, a discussion about the mechanisms of carbon-phosphorus couplings is still complicated specially in the case of long-range couplings that also are not frequently observed. In this study, 13 C NMR chemical shifts and coupling constants have been determined for a series of aryl esters of phosphoramidochloridic acid with the general formula: R2NP(O)(OAr)Cl, in which R = methyl and/or benzyl, Ar = p-tolyl. p-nitrophenyl, and phenyl. Besides usual W-couplings that could be found in these systems, we detected long-range couplings through five and six bonds. It has been shown that, these couplings are highly dependent on substituents on phosphorus nuclei. The data for some related compounds have been also obtained for a comparison. 相似文献
33.
Nonlinear Dynamics - This paper applies three forms of integration tools to integrate KdV6 equation that represents a nonholonomic deformation of the well-known KdV equation, which models... 相似文献
34.
Hormoz Eslami Shiping Zhu 《Journal of polymer science. Part A, Polymer chemistry》2006,44(6):1914-1925
The emulsion atom transfer radical block copolymerization of 2‐ethylhexyl methacrylate (EHMA) and methyl methacrylate (MMA) was carried out with the bifunctional initiator 1,4‐butylene glycol di(2‐bromoisobutyrate). The system was mediated by copper bromide/4,4′‐dinonyl‐2,2′‐bipyridyl and stabilized by polyoxyethylene sorbitan monooleate. The effects of the initiator concentration and temperature profile on the polymerization kinetics and latex stability were systematically examined. Both EHMA homopolymerization and successive copolymerization with MMA proceeded in a living manner and gave good control over the polymer molecular weights. The polymer molecular weights increased linearly with the monomer conversion with polydispersities lower than 1.2. A low‐temperature prepolymerization step was found to be helpful in stabilizing the latex systems, whereas further polymerization at an elevated temperature ensured high conversion rates. The EHMA polymers were effective as macroinitiators for initiating the block polymerization of MMA. Triblock poly(methyl methacrylate–2‐ethylhexyl methacrylate–methyl methacrylate) samples with various block lengths were synthesized. The MMA and EHMA reactivity ratios determined by a nonlinear least‐square method were ~0.903 and ~0.930, respectively, at 70 °C. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1914–1925, 2006 相似文献
35.
M. Eslami 《Journal of Optimization Theory and Applications》1993,77(3):591-612
In this article, we present an algorithm leading to an optimal controller gain for the automatic regulation of a linear system (closed-loop policy) and to an optimal auxiliary input. This is used for the purpose of either system identification, resulting in the maximum sensitivity measure and thus increased accuracy (Refs. 1–25), or system sensitivity reduction, resulting in the minimum sensitivity measure and thus reliable operation (Refs. 26–46). These results, which are robust in terms of parameter variations, are developed without constraints on the input functions. 相似文献
36.
Ziba Eslami 《组合设计杂志》2003,11(5):312-316
In this article, we employ trades to construct an instance of an LS[7](3,5,11) which is the smallest unresolved LS[7](3,k,v) [ 9 ]. © 2003 Wiley Periodicals, Inc. J Combin Designs 11: 312–316, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jcd.10021 相似文献
37.
38.
Spin-dependent electronic transport through an open multiple-quantum-dot ring threaded by a magnetic flux is theoretically investigated by using the single particle Green?s function method. By introducing local Rashba spin–orbit interaction on an individual quantum dot and local magnetic moments on two of other quantum dots, we calculate the spin-polarization in the output lead. We find the spin-polarization can be tuned by manipulating magnetic moments, adjusting magnetic flux and setting the Rashba spin–orbit strength. It is also shown the system can operate as an efficient spin-inverter when the structure is adjusted properly. The analysis can be utilized in designing optimized nanodevices. 相似文献
39.
40.