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901.
Christian Pötzsche 《Journal of Differential Equations》2008,245(5):1210-1242
We derive a linearization theorem in the framework of dynamic equations on time scales. This extends a recent result from [Y. Xia, J. Cao, M. Han, A new analytical method for the linearization of dynamic equation on measure chains, J. Differential Equations 235 (2007) 527-543] in various directions: Firstly, in our setting the linear part need not to be hyperbolic and due to the existence of a center manifold this leads to a generalized global Hartman-Grobman theorem for nonautonomous problems. Secondly, we investigate the behavior of the topological conjugacy under parameter variation.These perturbation results are tailor-made for future applications in analytical discretization theory, i.e., to study the relationship between ODEs and numerical schemes applied to them. 相似文献
902.
Christian Lubich. 《Mathematics of Computation》2005,74(250):765-779
The Dirac-Frenkel-McLachlan variational principle is the basic tool for obtaining computationally accessible approximations in quantum molecular dynamics. It determines equations of motion for an approximate time-dependent wave function on an approximation manifold of reduced dimension. This paper gives a near-optimality result for variational approximations. It bounds the error in terms of the distance of the exact wave function to the approximation manifold and identifies the parameters that control the deviation of the variational approximation from the best approximation on the manifold.
903.
In real catalyst systems, it is difficult to establish a correlation between catalytic properties and the shape (crystal planes, corners and steps) of the active catalytic particles. In this paper we present a clear shape dependence of the catalytic properties of a Vulcan‐supported fuel cell catalyst having 4 nm cubo‐octahedral platinum(0) nanocrystallites with (111) and (100) surfaces stabilized by sodium polyacrylate. The electrode materials were characterized by CO‐stripping cyclic voltammetry and transmission electron microscopy (TEM), showing that no agglomeration had occurred among the nanoparticles on the catalyst surfaces. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
904.
905.
W.R. Christian BeyerKatharina Woithe Bettina LükeMichael Schindler Horst AntonicekJürgen Scherkenbeck 《Tetrahedron》2011,67(17):3062-3070
The indole alkaloid α-cyclopiazonic acid (CPA) is one of the few known inhibitors of sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) besides the terpenoids thapsigargin and artemisinin. We report here the first asymmetric total synthesis of cyclopiazonic acid by a modification of the Knight synthesis, currently the most efficient route to CPA. First structure-activity data of CPA derivatives and stereoisomers are presented and will be discussed in connection with the published crystal structures of CPA-SERCA complexes. 相似文献
906.
907.
Krzysztof Ejsmont Jean‐Pierre Joly Emmanuel Wenger Benoit Guillot Christian Jelsch 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(7):o342-o344
The structural model for the title compound, C16H12N2O2, was refined using a multipolar atom model transferred from an experimental electron‐density database. The refinement showed some improvements of crystallographic statistical indices when compared with a conventional spherical neutral‐atom refinement. The title compound adopts a half‐chair conformation. The amide N atom lies almost in the plane defined by the three neighbouring C atoms. In the crystal structure, molecules are linked by weak intermolecular C—H...O and C—H...π hydrogen bonds. 相似文献
908.
A. Stephen K. Hashmi Prof. Dr. Christian Lothschütz Dipl.‐Chem. Martin Ackermann Dipl.‐Chem. René Doepp Dipl.‐Chem. Sankaran Anantharaman Benjamin Marchetti Dipl.‐Chem. Helmut Bertagnolli Prof. Dr. Frank Rominger Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(27):8012-8019
Gold complexes were prepared and investigated as catalysts for the oxidative esterification of aldehydes. Stabilisation by pyridine ligands gave good conversions and the in situ extended X‐ray absorption fine structure (EXAFS) study of the reactions indicated that the reaction mixtures contained only mononuclear gold species. Thus, this is the first proof for a homogeneous gold‐catalysed oxidation reaction; the presence of nanoparticles could be excluded experimentally. 相似文献
909.
910.