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91.
The theoretical considerations and the experimental data to calculate the activation energy of the ethylene oligomerization using a microreactor in a differential thermal analyzer are presented. 相似文献
92.
Michel Auriel Edmond De Hoffmann Philippe Scheers Etienne Deffense 《Journal of mass spectrometry : JMS》1989,24(1):1-7
The mass spectra of some 1,3,4-substituted azetidin-2-ones are measured. Fragmentation pathways are confirmed by use of both high-resolution and mass-analysed ion kinetic energy. They are consistent with the possible [2 + 2]- cycloadditions through which the azetidin-2-ones may be synthesized. More attention has to be paid to further fragmentations of the main fragments in assessing the preferred fragmentation mode. Influence of side-chain substituents is discussed. 相似文献
93.
94.
Since the original work of Dantzig and Wolfe in 1960, the idea of decomposition has persisted as an attractive approach to large-scale linear programming. However, empirical experience reported in the literature over the years has not been encouraging enough to stimulate practical application. Recent experiments indicate that much improvement is possible through advanced implementations and careful selection of computational strategies. This paper describes such an effort based on state-of-the-art, modular linear programming software (IBM's MPSX/370). 相似文献
95.
Etienne M Grosso D Boissière C Sanchez C Walcarius A 《Chemical communications (Cambridge, England)》2005,(36):4566-4568
We provide the first electrochemical evidence of permeability changes in continuous mesoporous TiO2 thin film electrodes induced by nanocrystallisation. 相似文献
96.
M. de Murcia D. Block D. Etienne J.P. Fillard 《Journal of Physics and Chemistry of Solids》1980,41(11):1247-1252
The orange luminescence at 2.15eV of As-grown ZnS0.52Se0.48crystals has been studied. The peak energy, halfwidth and Gaussian band shape exhibit a temperature dependence which is similar to that of the self-activated (SA) luminescence of ZnS at 2.66 eVand to that of ZnSe at 2.03 eV, and which can be described satisfactorily by a configurational coordinate model. However, optically detected magnetic resonance experiments at 1.8 K show that the luminescence is due to the recombination of an electron thermally released from a donor state with a hole trapped at an A-center acceptor state. The temperature dependence of the thermoluminescence spectra above 77 K and their spectral shift under additional IR exposure are also consistent with radiative recombination involving distant donor-acceptor pairs. 相似文献
97.
Yemele Bouberte M Krohn K Hussain H Dongo E Schulz B Hu Q 《Natural product research》2006,20(9):842-849
Tithoniamarin (1), a new isocoumarin dimer and a new ceramide, named tithoniamide (2a), have been isolated from Tithonia diversifolia, in addition to the known beta-sitosterol and beta-sitosterol glucopyranoside. The structures were elucidated on the basis of spectroscopic and chemical evidence. Preliminary studies showed that 1 has antifungal and herbicidal activities against Microbotryum violaceum and Chlorella fusca. 相似文献
98.
QM/MM calculations are used to elucidate the Poulos-Kraut (Poulos, T. L.; Kraut, J. J. Biol. Chem. 1980, 255, 8199-8205) mechanism of O-O bond activation and Compound I (Cpd I) formation in HRP, in conditions corresponding to neutral to basic pH. Attempts to generate Compound I directly from the Fe(H2O2) complex by migrating the proton from the proximal oxygen to the distal one (1,2- proton shift) result in high barriers. The lowest energy mechanism was found to involve initial deprotonation of ferric hydrogen peroxide complex (involving spin crossover from the quartet to the doublet state) by His42 to form ferric-hydroperoxide (Cpd 0). Subsequently, the distal OH group of Cpd 0 is pulled by Arg38 and reprotonated by His42(H+) to form Cpd I and a water molecule that bridges the two residues. The structures of the intermediate and the transition state reveal the manner by which the Arg-His residues promote cooperatively the electronic reorganization that is required to attend the heterolytic O-O cleavage. 相似文献
99.
Etienne Adam 《Stochastic Processes and their Applications》2018,128(9):2905-2922
We classify the possible behaviors of a class of one-dimensional stochastic recurrent growth models. In our main result, we obtain nearly optimal bounds for the tail of hitting times of some compact sets. If the process is an aperiodic irreducible Markov chain, we determine whether it is null recurrent or positive recurrent and in the latter case, we obtain a subgeometric convergence of its transition kernel to its invariant measure. We apply our results in particular to state-dependent Galton–Watson processes and we give precise estimates of the tail of the extinction time. 相似文献
100.
We consider semidefinite programming relaxations of the quadratic assignment problem, and show how to exploit group symmetry
in the problem data. Thus we are able to compute the best known lower bounds for several instances of quadratic assignment
problems from the problem library: (Burkard et al. in J Global Optim 10:291–403, 1997). 相似文献