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排序方式: 共有61条查询结果,搜索用时 31 毫秒
1.
It is suggested that the question of existence of a jamming phase transition in a broad class of single-lane cellular-automaton traffic models may be studied using a correspondence to the asymmetric chipping model. In models where such correspondence is applicable, jamming phase transition does not take place. Rather, the system exhibits a smooth crossover between free-flow and jammed states, as the car density is increased. 相似文献
2.
A. G. Khorti E. N. Glibin Z. I. Korshunova O. F. Ginzburg A. D. Ziv V. V. Nesterov O. I. Kurenbin 《Russian Chemical Bulletin》1991,40(10):1983-1986
The retention of crown compounds in reverse-phase HPLC is determined by their ability to bind to cations present in the eluent. The dependence of the retention of crown compounds on concentration of the binding cation has a break. This enables the stability constant of the crown-compound-cation complex to be calculated. The retention of the antitumor antibiotic actinomycin D in 75% MeOH is demonstrated to depend on [Na+] and not on [K+] for concentrations of the latter from 10–6 to 10–1 M.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2265–2269, October, 1991. 相似文献
3.
4.
By varying the absorption coefficient and width of an intralipid-India ink solution in a quasi-one-dimensional experiment, we investigate the transition between the ballistic and the diffusive regimes. The medium's attenuation coefficient changes abruptly between two different values within a single mean free path. This problem is analyzed both experimentally and theoretically, and it is demonstrated that the transition location depends on the scattering coefficient as well as on the measuring solid angle. 相似文献
5.
Ziv Hellman 《International Journal of Game Theory》2014,43(1):193-213
We show that the no betting characterisation of the existence of common priors over finite type spaces extends only partially to improper priors in the countably infinite state space context: the existence of a common prior implies the absence of a bounded agreeable bet, and the absence of a common improper prior implies the existence of a bounded agreeable bet. However, a type space that lacks a common prior but has a common improper prior may or may not have a bounded agreeable bet. As a side-benefit of the proofs here, we also obtain a constructive proof of the no betting characterisation in finite spaces. 相似文献
6.
Coating Platinum Nanoparticles with Methyl Radicals: Effects on Properties and Catalytic Implications
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Dr. Ronen Bar‐Ziv Dr. Israel Zilbermann Dr. Michael Shandalov Prof. Dr. Vladimir Shevchenko Prof. Dr. Dan Meyerstein 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(52):19000-19009
It was recently reported that the reaction of methyl radicals with Pt0 nanoparticles (NPs), prepared by the reduction of Pt(SO4)2 with NaBH4, is fast and yields as the major product stable (Pt0‐NPs)?(CH3)n and as side products, in low yields, C2H6, C2H4, and some oligomers. We decided to study the effect of this coating on the properties of the Pt0‐NPs. The results show that the coating can cover up to 75 % of the surface Pt0 atoms. The rate constant of the reaction, k( . CH3+Pt0‐NPs), decreases with the increase in the surface coverage, leading to competing reaction paths in the solution, which gradually become dominant, affecting the composition of the products. The methyl coating also affects the zeta potential, the UV spectra, and the electrocatalytic reduction of water in the presence of the NPs. Thus, the results suggest that binding alkyl radicals to Pt0 surfaces might poison the NPs catalytic activity. When the Pt0‐NPs are prepared by the reduction of a different precursor salt, PtCl62?, nearly no C2H4 and oligomers are formed and the methyl coating covers a larger percentage of the surface Pt0 atoms. The difference is attributed to the morphology of the Pt0‐NPs: those prepared from Pt(SO4)2 are twinned nanocrystals, whereas those prepared from PtCl62? consist mostly of single crystals. Thus, the results indicate that the side products, or most of them at least, are formed on the twinned Pt0 nanocrystal edges created between (111) facets. In addition, the results show that Pt0‐NPs react very differently compared with other noble metals, for example, Au0 and Ag0; this difference is attributed in part to the difference in the bond strength, (M0‐NP)?CH3, and should be considered in heterogeneous catalytic processes involving alkyl radicals as intermediates. 相似文献
7.
Ziv Ran 《Geometric And Functional Analysis》2008,18(1):184-221
A Lie atom is essentially a pair of Lie algebras and its deformation theory is that of a deformation with respect to the first
algebra, endowed with a trivialization with respect to the second. Such deformations occur commonly in algebraic geometry,
for instance as deformations of subvarieties of a fixed ambient variety. Here we study some basic notions related to Lie atoms,
focussing especially on their deformation theory, in particular the universal deformation. We introduce Jacobi–Bernoulli cohomology,
which yields the deformation ring, and show that, under suitable hypotheses, infinitesimal deformations are classified by
certain Kodaira–Spencer data.
Received: May 2006 Revision: January 2007 Accepted: March 2007 相似文献
8.
Ferrioxamine B analogues: targeting the FoxA uptake system in the pathogenic Yersinia enterocolitica
Kornreich-Leshem H Ziv C Gumienna-Kontecka E Arad-Yellin R Chen Y Elhabiri M Albrecht-Gary AM Hadar Y Shanzer A 《Journal of the American Chemical Society》2005,127(4):1137-1145
A series of ferrioxamine B analogues that target the bacterium Yersinia enterocolitica were prepared. These iron carriers are composed of three hydroxamate-containing monomeric units. Two identical monomers consist of N-hydroxy-3-aminopropionic acid coupled with beta-alanine, and a third unit at the amino terminal is composed of N-hydroxy-3-aminopropionic acid and one of the following amino acids: beta-alanine (1a), phenylalanine (1b), cyclohexylalanine (1c), or glycine (1d). Thermodynamic results for representatives of the analogues have shown a strong destabilization (3-4 orders of magnitude) of the ferric complexes with respect to ferrioxamine B, probably due to shorter spacers and a more strained structure around the metal center. No significant effect of the variations at the N-terminal has been observed on the stability of the ferric complexes. By contrast, using in vivo radioactive uptake experiments, we have found that these modifications have a substantial effect on the mechanism of iron(III) uptake in the pathogenic bacteria Yersinia enterocolitica. Analogues 1a and 1d were utilized by the ferrioxamine B uptake system (FoxA), while 1b and 1c either used different uptake systems or were transported to the microbial cell nonspecifically by diffusion via the cell membrane. Transport via the FoxA system was also confirmed by uptake experiments with the FoxA deficient strain of Yersinia enterocolitica. A fluorescent marker, attached to 1a in a way that did not interfere with its biological activity, provided additional means to monitor the uptake mechanism by fluorescence techniques. Of particular interest is the observation that 1a was utilized by the uptake system of ferrioxamine B in Yersinia enterocolitica (FoxA) but failed to use the ferrioxamine uptake route in Pseudomonas putida. Here, we present a case in which biomimetic siderophore analogues deliberately designed for a particular bacterium can distinguish between related uptake systems of different microorganisms. 相似文献
9.
10.
We study a filtered generalization of the operation of elementary modification of vector bundles. The generalization is motivated by applications to the degeneration theory of linear systems. 相似文献