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991.
Rate coefficients for the reaction of OH with Cl2, (k1), Br2, (k2) and I2, (k3), were measured under pseudo‐first‐order conditions in OH. OH was produced by pulsed laser photolysis of H2O2 (or HNO3) and its temporal profile was monitored by laser‐induced fluorescence. The measured rate coefficients for k1 (231–354 K) and k2 (235–357 K) are: k1 (T) = (3.77 ± 1.02) × 10−12 exp[−(1228 ± 140)/T] cm3 molecule−1 s−1 k2 (T) = (1.98 ± 0.51) × 10−11 exp[(238 ± 70)/T] cm3 molecule−1 s−1 k3 was independent of temperature between 240 and 348 K with an average value of (2.10 ± 0.60) × 10−10 cm3 molecule−1 s−1. The quoted uncertainties are 2σ (95% confidence limits, 1σA = AσlnA) and include estimated systematic errors. Our measurements significantly im‐prove the accuracy of k1. This is the first report of a slight negative temperature dependence for k2 and of the temperature independence of k3. © 1999 John Wiley & Sons, Inc.* Int J Chem Kinet 31: 417–424, 1999 相似文献
992.
Gilles Blanchard 《Annales de l'Institut Henri Poincaré (B) Probabilités et Statistiques》1999,35(6):793
We present a version of O. Catoni's “progressive mixture estimator” (1999) suited for a general regression framework. Following basically Catoni's steps, we derive strong non-asymptotic upper bounds for the Kullback–Leibler risk in this framework. We give a more explicit form for this bound when the models considered are regression trees, present a modified version of the estimator in an extended framework and propose an approximate computation using a Metropolis algorithm. 相似文献
993.
994.
The kinetics of the reactions CH3O + Cl → H2CO + HCl (1) and CH3O + ClO → H2CO + HOCl (2) have been studied using the discharge-flow techniques. CH3O was monitored by laser-induced fluorescence, whereas mass spectrometry was used for the detection or titration of other species. The rate constants obtained at 298 K are: k1 = (1.9 ± 0.4) × 10−11 cm3 molecule−1 s−1 and k2 = (2.3 ± 0.3) × 10−11 cm3 molecule−1 s−1. These data are useful to interpret the results of the studies of the reactions of CH3O2 with Cl and ClO which, at least partly, produce CH3O radicals. © 1996 John Wiley & Sons, Inc. 相似文献
995.
Gilles Mezoul Thierry Lalot Maryvonne Brigodiot Ernest Maréchal 《Macromolecular rapid communications》1995,16(8):613-620
The lipase-catalyzed preparation of poly(1,6-hexanediyl maleate) by transesterification of 1,6-hexanediol and dimethyl maleate is described. A configurationally pure poly(1,6-hexanediyl maleate) exhibiting exclusively cis structure was obtained. During the reaction, a substantial amount of macrolactones was formed. They were isolated, and the cyclic oligomer with y = 2 was found to predominate. Cycles are semi-crystalline, while no melting point was detected for the linear poly(1,6-hexanediyl maleate). We assume that the linear unsaturated polyester is completely amorphous owing to its cis configuration. 相似文献
996.
997.
998.
A branch and cut algorithm for nonconvex quadratically constrained quadratic programming 总被引:12,自引:0,他引:12
Charles Audet Pierre Hansen Brigitte Jaumard Gilles Savard 《Mathematical Programming》2000,87(1):131-152
We present a branch and cut algorithm that yields in finite time, a globally ε-optimal solution (with respect to feasibility
and optimality) of the nonconvex quadratically constrained quadratic programming problem. The idea is to estimate all quadratic
terms by successive linearizations within a branching tree using Reformulation-Linearization Techniques (RLT). To do so, four
classes of linearizations (cuts), depending on one to three parameters, are detailed. For each class, we show how to select
the best member with respect to a precise criterion. The cuts introduced at any node of the tree are valid in the whole tree,
and not only within the subtree rooted at that node. In order to enhance the computational speed, the structure created at
any node of the tree is flexible enough to be used at other nodes. Computational results are reported that include standard
test problems taken from the literature. Some of these problems are solved for the first time with a proof of global optimality.
Received December 19, 1997 / Revised version received July 26, 1999?Published online November 9, 1999 相似文献
999.
G. Duvey F. Nivoliers P. Rocca A. Godard F. Marsais G. Quguiner 《Journal of heterocyclic chemistry》2001,38(5):1039-1044
Various 4‐substituted benzo[c][2,7]naphthyridines were prepared from the corresponding 4‐chloro derivative by Pd(0) coupling reaction or nucleophilic substitution. More particularly, 4‐aroyl‐benzo[e][2,7]naph‐thyridines were synthesized by aroylation with arenecarbaldehydes in the presence of 1,3‐dimethylimida‐zolium iodide. 相似文献
1000.
We propose in this paper a novel integration of local search algorithms within a constraint programming framework for combinatorial optimization problems, in an attempt to gain both the efficiency of local search methods and the flexibility of constraint programming while maintaining a clear separation between the constraints of the problem and the actual search procedure. Each neighborhood exploration is performed by branch-and-bound search, whose potential pruning capabilities open the door to more elaborate local moves, which could lead to even better approximate results. Two illustrations of this framework are provided, including computational results for the traveling salesman problem with time windows. These results indicate that it is one order of magnitude faster than the customary constraint programming approach to local search and that it is competitive with a specialized local search algorithm. 相似文献