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排序方式: 共有416条查询结果,搜索用时 31 毫秒
31.
The novel catalytic system, composed of a ruthenium alkylidene containing a surfactant fragment in the catalysts molecule, is reported. Ring closing metathesis and cross metathesis reactions proceed efficiently in neat water at room temperature, in air, without need of adding an external surfactant. 相似文献
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Similar to atoms and nuclei, semiconductor quantum dots exhibit the formation of shells. Predictions of magnetic behavior of the dots are often based on the shell occupancies. Thus, closed-shell quantum dots are assumed to be inherently nonmagnetic. Here, we propose a possibility of magnetism in such dots doped with magnetic impurities. On the example of the system of two interacting fermions, the simplest embodiment of the closed-shell structure, we demonstrate the emergence of a novel broken-symmetry ground state that is neither spin singlet nor spin triplet. We propose experimental tests of our predictions and the magnetic-dot structures to perform them. 相似文献
34.
Rafał Latała 《Israel Journal of Mathematics》2014,203(1):295-308
We show that the L 1-norm of linear combinations (with scalar or vector coefficients) of products of i.i.d. nonnegative mean one random variables is comparable to the l 1-norm of the coefficients. 相似文献
35.
Rafa? Filipów 《Journal of Combinatorial Theory, Series A》2010,117(7):943-956
We characterize ideals of subsets of natural numbers for which some versions of Schur's theorem hold. These are similar to generalizations shown by Bergelson (1986) in [1] and Frankl, Graham and Rödl (1990) in [7]. Additionally, we prove a generalization of an iterated version of Ramsey's theorem. 相似文献
36.
Cyclometalated Iridium(III) Complexes Containing Semicarbazone Ligands: Synthesis,Characterization, Photophysical and Biological Studies
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Marion Graf Yvonne Gothe Nils Metzler‐Nolte Rafał Czerwieniec Karlheinz Sünkel 《无机化学与普通化学杂志》2015,641(10):1798-1802
The synthesis, crystal structure, photophysical properties, and biological activity of the novel bis‐cyclometalated complexes [Ir(ptpy)2(vnsc)] ( 2 ) and [Ir(ptpy)2(acsc)] ( 3 ) [ptpy = 2‐(p‐tolyl)pyridinato, vnsc = vanillin semicarbazone, acsc = acetone semicarbazone] are described. The new compounds were prepared by the reaction of [{Ir(μ‐Cl)(ptpy)2}2] ( 1 ) with the corresponding semicarbazone ligands under basic conditions. The molecular structure of compound 3 was confirmed by a single‐crystal X‐ray diffraction study. The complex crystallized from chloroform as a mono‐ solvate in the orthorhombic space group Pcab with eight molecules in the unit cell. 相似文献
37.
Rafał Ślusarz Justyna Samaszko-Fiertek Barbara Dmochowska Janusz Madaj 《Journal of carbohydrate chemistry》2017,36(1):45-58
Computational investigations were performed to examine the effects of the addition of 2-acetamido-2-deoxy-β-D-galactopyranosylamine or 1-amino-1-deoxy-D-glucitol connected to the C-terminus of vancomycin with different linkers. The purpose of this modification was to find more effective vancomycin derivatives by providing alternative interactions between vancomycin moiety and the peptidoglycan precursor. Each prepared vancomycin–peptidoglycan complex was optimized and submitted to the molecular dynamics study and analysis. The analysis of overall root mean square deviation, changes in position and interactions involving modified part of vancomycin as well as cluster analysis were carried out. One of the proposed vancomycin analogues seems to be efficient vancomycin substitute. 相似文献
38.
In a recent paper (Appl. Math. Comput. 215:1622–1645, 2009), the authors proposed a method of summation of some slowly convergent series. The purpose of this note is to give more theoretical analysis for this transformation, including the convergence acceleration theorem in the case of summation of generalized hypergeometric series. Some new theoretical results and illustrative numerical examples are given. 相似文献
39.
We prove a characterization showing when the ideal pointwise convergence does not imply the ideal equal (aka quasi-normal) convergence. The characterization is expressed in terms of a cardinal coefficient related to the bounding number b. We also prove a characterization showing when the ideal equal limit is unique. 相似文献
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