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71.
The oxidation of cyclooctane (1) to cyclooctanone (3) with molecular oxygen and acetaldehyde (2) as a co-reductant occurs efficiently in the presence of compressed CO2. Up to 20% yields of 3 are obtained under optimised multiphase conditions. 相似文献
72.
73.
Monovacancy diffusion alone dominates over diffusion due to divacancies and interstitials in Al for all temperatures up to the melting point. Deviations from a single Arrhenius dependence are due to anharmonicity. The conclusion is based on a combination of theoretical methods, from density functional theory to thermodynamic integration, without fitting to experimental data. The calculated diffusion rate agrees with experimental data over 11 orders of magnitude. 相似文献
74.
75.
76.
Femtosecond three-pulse photon-echo studies of acetic acid dimers in solution reveal multilevel coherence of O-H stretching excitations caused by the anharmonic coupling between the high-frequency stretching and low-frequency hydrogen-bond motions. We demonstrate for the first time that such multilevel coherence determines the nonexponential decay of the macroscopic O-H stretching polarization, whereas spectral diffusion processes play a minor role. The dephasing time of individual vibrational transitions contributing to the overall polarization is approximately 200 fs. 相似文献
77.
We study the expansion of derivatives along orbits of real and complex one-dimensional mapsf, whose Julia setJ
f attracts a finite setCrit of non-flat critical points. Assuming that for eachcεCrit, either |D f
n(f(c))|→∞ (iff is real) orb
n·|Df
n(f(c))|→∞ for some summable sequence {b
n} (iff is complex; this is equivalent to summability of |D f
n(f(c))|−1), we show that for everyxεJ
f\U
i
f
−i(Crit), there existℓ(x)≤max
c
ℓ(c) andK′(x)>0
for infinitely manyn. Here 0=n
s<…<n
1<n
0=n are so-called critical times,c
i is a point inCrit (or a repelling periodic point in the boundary of the immediate basin of a hyperbolic periodic attractor), which shadows
orb(x) forn
i−ni
+1 iterates, and
, for uniform constantsK>0 and λ>1. If allcεCrit have the same critical order, thenK′(x) is uniformly bounded away from 0. Several corollaries are derived. In the complex case, eitherJ
f=
orJ
f has zero Lebesgue measure. Also (assuming all critical points have the same order) there existk>0 such that ifn is the smallest integer such thatx enters a certain critical neighbourhood, then |Df
n(x)|≥k.
The original paper used an incorrect version of the Koebe Lemma cited from [21] as was pointed out by the referee and Genadi
Levin in the autumn of 2001. The corrected version of November 2001 only uses the classical Koebe Lemma. Apparently, all results
in Feliks Przytycki’s paper [21] go through using the classical Koebe Lemma instead of his Lemma 1.2.
Both authors gratefully acknowledge the support of the PRODYN program of the European Science Foundation. HB was partially
supported by a fellowship of The Royal Netherlands Academy of Arts and Sciences (KNAW). SvS was partially supported by GR/M82714/01. 相似文献
78.
Nils Byrial Andersen Gestur Ó lafsson 《Proceedings of the American Mathematical Society》2001,129(1):173-179
We formulate and prove a topological Paley-Wiener theorem for the normalized spherical Laplace transform defined on the rank 1 causal symmetric spaces , for .
79.
Nils M. Bezares-Roder Hemwati Nandan Heinz Dehnen 《International Journal of Theoretical Physics》2007,46(10):2429-2436
The exact static and spherically symmetric solutions of the vacuum field equations for a Higgs Scalar-Tensor theory (HSTT)
are derived in Schwarzschild coordinates. It is shown that in general there exists no Schwarzschild horizon and that the fields
are only singular (as naked singularity) at the center (i.e. for the case of a point-particle). However, the Schwarzschild
solution as in usual general relativity (GR) is obtained for the vanishing limit of Higgs field excitations. 相似文献
80.
The characteristic connection of an almost hermitian structure is a hermitian connection with totally skew-symmetric torsion. The case of parallel torsion in dimension 6 is of particular interest. In this work, we give a full classification of the algebraic types of the torsion form, and, on the basis of this, undertake a systematic investigation into the possible geometries. Numerous naturally reductive spaces are constructed and classified, and examples on nilmanifolds given. 相似文献