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131.
132.
Journal of Nonlinear Science - An important aspect of understanding FPU chains is the existence of invariant manifolds (called “bushes”) in FPU chains. We will focus on the classical... 相似文献
133.
Mauricio Gomes Constantino Luiz Gonzaga de Oliveira Matias Gil Valdo José da Silva Vladimir Constantino Gomes Heleno Maria Teresa do Prado Gambardella 《合成通讯》2013,43(24):4285-4295
Abstract: In this paper we describe a very short stereoselective synthesis of the β-ethoxylactone 13, a model structure for compounds isolated from Otoba parvifolia. The method, which also produces β-hydroxy-esters and β-hydroxy-lactones, is based on a chemo- and stereoselective Reformatsky reaction. 相似文献
134.
Marek Fikrle Jan Kučera Ferdinand Šebesta 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(3):661-663
Several procedures for preparation of the 95mTc radiotracer following irradiation of a thin Mo target with deuterons were tested. The procedures consisting of alkaline-oxidative
fusion of the irradiated target in a mixture of Na2O2 + NaOH and subsequent liquid–liquid extraction with 2-butanone, and acid decomposition of the target in a mixture of H2SO4 + HNO3 followed by extraction chromatography with PAN-Aliquat 336 composite material appeared suitable for the given purpose. 相似文献
135.
Moser C Orthaber A Nieger M Belaj F Pietschnig R 《Dalton transactions (Cambridge, England : 2003)》2006,(32):3879-3885
A facile synthetic access to the homologous series of 1,1'-ferrocenylene bisdihalophosphanes Fc'(PX2)2 (X = F, Cl, Br, I; Fc' = 1,1'-ferrocenediyl = ferrocenylene = -C5H4FeC5H4-) is reported. The 31P NMR spectroscopic data of this series suggest a similar electronic interaction of the -PX(2) unit with the ferrocene system as in monofunctional ferrocenyldihalophosphanes. Crystal structures for Fc'(PCl2)2 and Fc'(PBr2)2 reveal that the nature of the halogen atom within the phosphane unit strongly influences the twist angle of the ferrocene system, while leaving the other structural parameters mostly unaffected. Based on these bisdihalophosphanes, a synthetic access to the first metallocene bridged bisphosphaalkene ((C5H4P=C(t-Bu)OTMS)2Fe) is reported in which the tert-butyl substituents provide sufficient steric pressure to control the E/Z isomeric ratio which leads to the almost exclusive formation of the most stable Z,Z isomer out of the three possible isomers. 相似文献
136.
A simple model based on Gaussian statistics, aimed at describing localized diffusive translational motion in one, two, and three dimensions is presented and used to calculate the corresponding incoherent neutron scattering laws. In the time domain, these laws are closed form mathematical functions. In the frequency domain, some of these laws can be expressed as an infinite series depending on one single index. Owing to this relative simplicity, such a model can advantageously replace previous models such as diffusion on a segment, inside a circle and inside a sphere with an impermeable surface, to analyze neutron quasielastic scattering data associated with molecular motions in confined media. It may also be more realistic when the confinement is defined by soft, ill-defined boundaries. 相似文献
137.
Riemann problems for the full set of Euler equations for two phases with phase transition are considered. Based on the assumptions across the phase boundary kinetic relations to describe the mass transfer between the phase are derived from the second law of thermodynamics. Self-similar as well as singular solutions can be constructed. For both cases the structure of the solution is discussed. 相似文献
138.
A new class of metric divergences on probability spaces and its applicability in statistics 总被引:2,自引:0,他引:2
Ferdinand Österreicher Igor Vajda 《Annals of the Institute of Statistical Mathematics》2003,55(3):639-653
The classI f β, βε(0, ∞], off-divergences investigated in this paper is defined in terms of a class of entropies introduced by Arimoto (1971,Information and Control,19, 181–194). It contains the squared Hellinger distance (for β=1/2), the sumI(Q 1‖(Q 1+Q 2)/2)+I(Q 2‖(Q 1+Q 2)/2) of Kullback-Leibler divergences (for β=1) and half of the variation distance (for β=∞) and continuously extends the class of squared perimeter-type distances introduced by Österreicher (1996,Kybernetika,32, 389–393) (for βε (1, ∞]). It is shown that\((I_{f_\beta } (Q_1 ,Q_2 ))^{\min (\beta ,1/2)}\) are distances of probability distributionsQ 1,Q 2 for β ε (0, ∞). The applicability of\(I_{f_\beta }\)-divergences in statistics is also considered. In particular, it is shown that the\(I_{f_\beta }\)-projections of appropriate empirical distributions to regular families define distribution estimates which are in the case of an i.i.d. sample of size'n consistent. The order of consistency is investigated as well. 相似文献
139.
Ferdinand Belaj Christoph Kratky Edgar Nachbaur Alois Popitsch 《Monatshefte für Chemie / Chemical Monthly》1987,118(1):19-23
A crystal structure analysis of the colourless AgSO3NH2 was carried out at room temperature:M=203.95, orthorhombic, Pcab,a=7.809 (2) Å,b=8.067 (2) Å,c=11.682 (3) Å,V=735.9 Å3,Z=8,d
x=3.681 Mgm–3,F(000)=760, Mo K, =0.71069 Å (graphite monochromator), =5.77 mm–1,R=4.36% (509 reflections, 56 parameters). The ionic structure shows approximate trigonal bipyramidal coordination around the Ag+-ions. 相似文献
140.
Melikyan GG Villena F Sepanian S Pulido M Sarkissian H Florut A 《Organic letters》2003,5(19):3395-3397
[reaction: see text] The spontaneous generation and stereoselective coupling of Co(2)(CO)(6)-complexed propargyl radicals have been discovered. One- and two-step complementary methods (Method A: (1) HBF(4); (2) CH(2)Cl(2), 20 degrees C; Method B: Tf(2)O, CH(2)Cl(2), 20 degrees C) provided an easy access to synthetically useful d,l-3,4-diaryl-1,5-alkadiynes (de 74-98%). 相似文献