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211.
Enantiomerically pure (R)-(+)-pipecolic acid was synthesized in four steps and 42% overall yield starting from dihydropyran and (R)-alpha-methylbenzylamine. A general short strategy is also described for preparing (S)-proline (47.5% overall yield) and derivatives. 相似文献
212.
Simultaneous temperature and 2D velocity measurements in a turbulent heated jet using combined laser-induced fluorescence and LDA 总被引:1,自引:0,他引:1
This paper presents an efficient technique for the characterization of thermal transport properties in turbulent flows. The
method is based on the temperature dependence of fluorescence, induced by laser radiation, of an organic dye. The laser-induced
fluorescence technique is combined with 2D laser Doppler anemometry, in order to measure in the same sample volume simultaneously
and instantaneously the temperature and velocity. The technique is demonstrated on a turbulent heated round jet: the mean
and fluctuating dynamic and thermal fields are investigated, and the temperature-velocity cross-correlations are determined
in order to characterize the turbulent diffusivity and the turbulent Prandtl number.
Received: 30 October 1997/Accepted: 14 July 1998 相似文献
213.
E. Benichou A.R. Allouche R. Antoine M. Aubert-Frecon M. Bourgoin M. Broyer Ph. Dugourd G. Hadinger D. Rayane 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,10(2):233-242
A non perturbative approach is used to solve the problem of a rigid linear molecule with both a permanent dipole moment and
a static dipole polarizability, in a static electric field. Eigenenergies are obtained and compared to perturbative low field
and high field approximations. Analytical expressions for the orientation parameters and for the gradient of the energy are
given. This non perturbative approach is applied to the simulation of beam deviation experiments in strong electric field.
Results of simulations are given for inhomogeneous alkali dimers. For LiNa, the simulations are compared to experimental data.
For LiK, deviation profiles have been simulated in order to prepare future experiments on this molecule.
Received 21 July 1999 and Received in final form 22 September 1999 相似文献
214.
Joel Friedman Antoine Joux Yuval Roichman Jacques Stern Jean-Pierre Tillich 《Random Structures and Algorithms》1998,12(4):335-350
We prove that for every r and d≥2 there is a C such that for most choices of d permutations π1, π2,…,πd of Sn, the following holds: for any two r-tuples of distinct elements in {1,…,n}, there is a product of less than C log n of the πis which map the first r-tuple to the second. Although we came across this problem while studying a rather unrelated cryptographic problem, it belongs to a general context of which random Cayley graph quotients of Sn are good expanders. © 1998 John Wiley & Sons, Inc. Random Struct. Alg., 12: 335–350, 1998 相似文献
215.
Antoine Ghanem 《Journal of Polymer Science.Polymer Physics》1999,37(10):997-1008
Although the depolarized light intensity technique has been known for some decades, the time dependence of light intensity does not yet seem to be well understood. In this article, devoted to the crystallization kinetics of polyvinylidene fluoride (PVDF), we present some of the problems associated with quantitative analysis. Parameters such as incident light intensity—in combination with the detection system—and specimen thickness are shown to dramatically affect the apparent kinetics. Experiments on single spherulites grown in very thin films can help interpret the intensity–time curve. Our results demonstrate that care should be taken when comparison is made between DLI and differential scanning calorimetry. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 997–1008, 1999 相似文献
216.
Stphanie Goumri‐Magnet Heinz Gornitzka Antoine Baceiredo Guy Bertrand 《Angewandte Chemie (International ed. in English)》1999,38(5):678-680
The first crystallographically characterized phosphonium yldiide 2 was obtained in a simple reaction by addition of n‐butyllithium to the stable phosphanyl(silyl)carbene 1 . R=cHex2N. 相似文献
217.
Antoine Pauthier 《Journal of Dynamics and Differential Equations》2018,30(3):1273-1293
We construct nontrivial entire solutions for a bistable reaction–diffusion equation in a class of domains that are unbounded in one direction. The motivation comes from recent results of Berestycki et al. (Calc Var Partial Differ Equ 55(3):1–32, 2016) concerning propagation and blocking phenomena in infinite domains. A key assumption in their study was the “cylinder-like” assumption: their domains are supposed to be straight cylinders in a half space. The purpose of this paper is to consider domains that tend to a straight cylinder in one direction. We need a different approach based on the long time stability of the bistable wave in heterogeneous media. We also prove the existence of an entire solution for a one-dimensional problem with a non-homogeneous linear term. 相似文献
218.
Natalia Bellido Charles Simon Antoine Maignan 《Journal of magnetism and magnetic materials》2009,321(11):1770-1772
Geometric frustration in magnetic systems is a key ingredient for magnetodielectric coupling. Ca3Co2O6 system is a model of triangular Ising lattice and presenting exotic magnetic properties. With a partially disordered antiferromagnetic ground state and two steps in magnetisation to a ferrimagnetic state and to a ferromagnetic state, this oxide is a good system for studying the effect of frustration in magnetodielectric coupling. Dielectric constant measurements of single crystals of Ca3Co2O6 have been done showing the sensitivity of this technique to frustration. 相似文献
219.
Antoine Suarez 《Foundations of Physics》2009,39(2):156-159
It is shown that the before-before (or Suarez-Scarani) experiment refutes hidden variable models with a deterministic (“realistic”) nonlocal part, whereas experiments violating Leggett-type inequalities refute models with biased random local part. Therefore the claim that Gröblacher et al. (Nature 446:871–875, 2007) present “an experimental test of nonlocal realism” is misleading, and Marek ?ukowski’s (Found. Phys. 38:1070, 2008) comment misses the point. A new experiment is suggested. 相似文献
220.