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21.
Bare G. Jacques PH. Hubert J. B. Rikir R. Thonart PH. 《Applied biochemistry and biotechnology》1991,28(1):445-456
Applied Biochemistry and Biotechnology - The ability of the yeastSaccharomyces cerevisiae to bioconvert stereo-selectively octyl-4-chloroacetoacetate (OCA) into the corresponding chiral alcohol,... 相似文献
22.
J. Bystricky P. Chaumette J. Deregel J. Fabre F. Lehar A. De Lesquen L. Van Rossum J.M. Fontaine J. Gosset F. Perrot C.A. Whitten J. Ball PH. Chesny C.R. Newsom J. Yonnet T. Niinikoski M. Rieubland A. Michalowicz S. Dalla Torre-Colautti 《Nuclear Physics B》1985,262(4):727-743
The spin correlation parameter Aoonn and the analyzing powers Aoono and Aooon were measured simultaneously, in the energy range 0.5–0.8 GeV and in the angular region 40°–80° CM. The experiment used the polarized proton beam of SATURNE II and the Saclay frozen spin polarized target. 相似文献
23.
Two recent methods (Shanno, 1978; Toint, 1980) for revisingestimates of sparse second derivative matrices in quasi-Newtonoptimization algorithms reduce to variable metric formulae whenthere are no sparsity conditions. It is proved that these methodsare equivalent. Further, some examples are given to show thatthe procedure may make the second derivative approximationsworse when the objective function is quadratic. Therefore theconvergence properties of the procedure are sometimes less goodthan the convergence properties of other published methods forrevising sparse second derivative approximations. 相似文献
24.
X. -Q. Ding E. L. Bominaar E. Bill H. Winkler A. X. Trautwein S. Drüeke PH. Chaudhuri K. Wieghardt 《Hyperfine Interactions》1990,53(1-4):311-315
In this paper, we briefly summarize the main conclusions of the Mössbauer analysis of [L2Fe2(-OH)3] (ClO4)2·2CH3OH·2H2O with L=N,N',N"-trimethyl-1,4,7-triazacyclononane, a novel dimeric iron compound, which possesses a central exchange-coupled delocalized-valence Fe(II/III) unit. The complete delocalization of the excess electron in the dimeric iron center is concluded from the indistinguishability of the two iron sites in Mössbauer spectroscopy. The magnetic Mössbauer spectra imply a system spinS
t=9/2 for the dimer in its ground state. The values for hyperfine and spin-Hamiltonian parameters, obtained from simulations of the Mössbauer spectra, are =0.74 mms–1, E
Q=–2.14 mms–1,A
=–10.6 T,A
=–13.5 T andD=1.8 cm–1. The system spinS
t=9/2 is interpreted to be a consequence of double-exchange coupling. 相似文献
25.
Emmanuelle Pioger Denis Wouessidjewe Dominique Duchêne Svetla Bogdanova 《Journal of inclusion phenomena and macrocyclic chemistry》1998,30(2):151-161
The influence of the water structure promoters, mannitol and sucrose, on the indomethacin/-cyclodextrin inclusion process at different pH values was evaluated using the phase solubility method and circular dichroism spectroscopy. The effect of mannitol and sucrose on the total solubilizing activity of -cyclodextrin as well as on the stabilization of the complex was moderate, and depended strongly on the pH value of the medium. The most pronounced effect on the association constant of the indomethacin inclusion compound was observed in KCl/HCl buffer of pH 1.6, because mannitol and sucrose, in the absence of -cyclodextrin, approximately double the indomethacin solubility so that the constant value decreases. On the other hand, a very strong complex formation between indomethacin and -cyclodextrin was observed in acid medium (KCl/HCl buffer, pH = 1.6), a fact not much discussed in the literature. The apparent association constant of the inclusion compound formed in the absence of mannitol or sucrose was found to be of the same order of magnitude as for the complex formed at pH 6.8. Changes in the optical activity of the indomethacin/-cyclodextrin inclusion complex were registered in the presence of sucrose, which interacts more strongly than mannitol with water molecules, and could probably adhere to the surface of the inclusion complex, thus changing its configuration and environment. 相似文献
26.
Within the context of the linearized theory of elasticity, weconsider homogeneous crystals, which have orthorhombic, tetragonal,hexagonal symmetry or cubic symmetry (RTHC crystals).When such a crystal is subjected to a simple tension (or compression)of amount T in the direction n, there will be three, generallydifferent, extensional strains along the three mutually perpendiculardirections corresponding to the principal axes of strain. Thepurpose of this paper is to present a simple procedure to placebounds, upper and lower, on the possible extensional strainsin the crystal, both in the case when n is fixed in directionand in the case when n is arbitrary. The procedure allows usto determine whether the bounds are attained or not. 相似文献
27.
28.
P.-H. Pioger V. Couderc L. Grossard A. Barthélémy F. Baronio C. De Angelis Y.H. Min V. Quiring W. Sohler 《Applied physics. B, Lasers and optics》2006,85(1):131-134
Experimental and numerical investigations of an ultra-fast reconfigurable spatial switch based on the nonlinear interaction between a weak wave (the signal) and a solitary wave (the control) at 1548 nm are reported. The non-collinear interaction in a quadratic nonlinear film waveguide gives birth to a third switched optical beam (the idler). This beam could be steered according to the transverse spatial position of the control beam. PACS 42.65.Ky; 42.65.Re; 42.65.Wi 相似文献
29.
Ultra-fast saturable absorber through spatial self-trapping and filtering in Ti:PPLN film waveguides
P.H. Pioger V. Couderc L. Lefort A. Barthélémy F. Baronio C. De Angelis Y.H. Min V. Quiring W. Sohler 《Applied physics. B, Lasers and optics》2003,77(6-7):571-576
Numerical and experimental investigations on ultra-fast all-optical saturable absorber on picosecond optical pulses at 1547 nm using spatial self-trapped propagation in a quadratic nonlinear film waveguide combined with spatial filtering are reported. The influences of phase-mismatch, pulse intensity and spatial filtering on the temporal reshaping mechanism are discussed to derive the optimum parameters. PACS 42.65.Ky, 42.65.Re, 42.65.Wi 相似文献
30.
Benisty H. Lalanne PH. Olivier S. Rattier M. Weisbuch C. Smith C.J.M. Krauss T.F. Jouanin C. Cassagne D. 《Optical and Quantum Electronics》2002,34(1-3):205-215
We address the issue of out-of-plane losses in two-dimensional (2D) photonic crystals (PC) etched through a GaAs monomode waveguide clad with standard GaAlAs alloys. We correlate experimental transmission of PCs with two kinds of loss simulation results. The first kind is 2D and introduces an ad hoc imaginary index in the air holes to account for the losses [see (Benisty et al. Appl. Phys. Lett. 76, 532, 2000)]. The second kind is a novel exact three-dimensional calculation inspired by grating-Fourier analysis that provides quantitatively unprecedented agreement with experimental measurements taking into account hole depth as a limiting parameter. We conclude that, in revision to the conclusions of the above reference, the experimental losses are not the intrinsic ones, being larger by a factor of 5 to 10 due to insufficient hole depth. The transition occurs at a critical etch depth shown to be here around 700 nm. We thus predict, for holes deeper than 700 nm, much improved crystals with very low transmission losses and microresonators with ultra-high quality factors. 相似文献