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1.
Summary Relationships between specific activity of bimetallic platinum catalysts in paraffin dehydrogenation and atomic sizes of promoters (i) and enthalpies of alloying with platinum (ii) were considered. The leading role of the size (geometric) effect was demonstrated. 相似文献
2.
Wolfson A Janssens S Vankelecom I Geresh S Gottlieb M Herskowitz M 《Chemical communications (Cambridge, England)》2002,(4):388-389
A new chiral heterogeneous catalytic system obtained by occlusion of the Rh-MeDuPHOS complex in a polydimethylsiloxane film was tested in the asymmetric hydrogenation of methyl 2-acetamidoacrylate in aqueous medium. 相似文献
3.
The activity of water in crown ether solutions has been obtained at 298,313 and 333 K over a wide range of concentrations. A minimum in the activity coefficient of water is observed. The minimum becomes more pronounced with decreasing temperature. 相似文献
4.
I. Fita D. Mogilyansky V. Markovich R. Puzniak A. Wisniewski L. Titelman L. Vradman M. Herskowitz V.N. Varyukhin G. Gorodetsky 《Journal of Non》2008,354(47-51):5204-5206
Magnetic and structural properties of nanocrystalline LaCoO3 with particle size ranging from 25 to 38 nm, prepared by the citrate method, were investigated. All nanoparticles exhibit ferromagnetism below TC ≈ 85 K. It was found that the unit-cell volume increases monotonically with decreasing particle size and ferromagnetic (FM) moment increases simultaneously with lattice expansion, whereas TC remains nearly unchanged. It appears that both magnetic and structural properties of LaCoO3 nanoparticles are size-dependent due to the surface effect. On the other hand, an applied pressure suppresses strongly the FM phase leading to its disappearance at ~11 kbar. Remarkably, the TC does not change visibly under pressure. Our data reveal that the ferromagnetism in LaCoO3 nanoparticles, likely related to the intermediate-spin (IS) Co3+ state, is simply controlled by the unit-cell volume. Within this scenario, the FM coupled IS states appear/disappear with expanding/compressing the lattice and/or Co–O bonds. 相似文献
5.
In this paper we extend Champernowne’s construction of a normal sequence in base b to the
case and obtain an explicit construction of the generic point of the
shift transformation of the set
. We prove that the intersection of the constructed configuration with an arbitrary polynomial curve in the plane is a normal
sequence in base b. 相似文献
6.
The dispersion relation for a granular bed with a small amount of fine bubbles is formulated and analyzed. It is assumed that the grain size is much larger than the bubble's radius and that their volume concentration is small. The study is motivated by the problem of acoustic diagnostics of fixed bed chemical reactors operating in multiphase flow regime. 相似文献
7.
A novel system consisting of Rh-DuPHOS and ionic liquid for asymmetric hydrogenations 总被引:1,自引:0,他引:1
Guernik S Wolfson A Herskowitz M Greenspoon N Geresh S 《Chemical communications (Cambridge, England)》2001,(22):2314-2315
The ionic liquid [bmim][PF6] was found to provide extra stability to the air-sensitive chiral catalyst Rh-MeDuPHOS in asymmetric hydrogenation of enamides. 相似文献
8.
9.
Solid alkaline metal hydroxides displayed high catalytic activity and full selectivity in the aerobic oxidation of benzylic
alcohols in a non-polar medium. The activity of the solid bases, in decreasing order of reactivity, was KOH > NaOH ≫ LiOH.
Water, which is the only by-product of the reaction, plays a crucial role in KOH deactivation by converting the crystal phase
of KOH to KOH · H2O, as confirmed by XRD measurements. 相似文献
10.
Mordechay B. Levin 《Israel Journal of Mathematics》2010,178(1):61-106
In this paper we describe a third class of low discrepancy sequences. Using a lattice Γ ? ? s , we construct Kronecker-like and van der Corput-like ergodic transformations T 1,Γ and T 2,Γ of [0, 1) s . We prove that for admissible lattices Γ, (T ν,Γ n (x))n≥0 is a low discrepancy sequence for all x ∈ [0, 1) s and ν ∈ {1, 2}. We also prove that for an arbitrary polyhedron P ? [0, 1) s , for almost all lattices Γ ∈ L s = SL(s,?)/SL(s, ?) (in the sense of the invariant measure on L s ), the following asymptotic formula holds with arbitrary small ? > 0, for all x ∈ [0, 1) s , and ν ∈ {1, 2}.
相似文献
$\# \{ 0 \le n < N:T_{v,\Gamma }^n(x) \in P\} = NvolP + O({(\ln N)^{s + \varepsilon }}),N \to \infty$