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141.
A stereoselective synthesis of the bacchopetiolone (1) carbocyclic core using a tandem phenolic oxidation/Diels-Alder reaction is described. [reaction: see text]. 相似文献
142.
Maximum likelihood estimation in a partially observed stratified regression model with censored data
Amélie Detais Jean-François Dupuy 《Annals of the Institute of Statistical Mathematics》2011,63(6):1183-1206
The stratified proportional intensity model generalizes Cox’s proportional intensity model by allowing different groups of
the population under study to have distinct baseline intensity functions. In this article, we consider the problem of estimation
in this model when the variable indicating the stratum is unobserved for some individuals in the studied sample. In this setting,
we construct nonparametric maximum likelihood estimators for the parameters of the stratified model and we establish their
consistency and asymptotic normality. Consistent estimators for the limiting variances are also obtained. 相似文献
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145.
Unprecedented Trinuclear AgI Complex with 2,4,6‐Tris(2‐pyrimidyl)‐1,3,5‐triazine as an Efficient Catalyst for the Aziridination of Olefins 下载免费PDF全文
Dr. Damir A. Safin Dr. Amélie Pialat Dr. Ilia Korobkov Prof. Muralee Murugesu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(16):6144-6149
An unprecedented trinuclear heteroleptic AgI complex was isolated using a stable multidentate 2,4,6‐tris(2‐pyrimidyl)‐1,3,5‐triazine (TPymT) ligand. The obtained compound is an efficient catalyst for the direct aziridination of terminal olefins. 相似文献
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Danièle CLAUSSE Isabelle PEZRON Amélie BEHAEGHEL 《Journal of Dispersion Science and Technology》2013,34(1-2):315-326
Water transfer between water droplets and water + NaCl droplets dispersed within emulsions have been pointed out by differential scanning calorimetry. Using a solution- diffusion model, water fluxes have been calculated. 相似文献
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149.
Fabien Pointurier Amélie Hubert Anne-Claire Pottin 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(2):609-616
In this paper we describe the application of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) coupling to particle analysis, i.e., the determination of the isotopic composition of micrometric uranium particles. The performances of this analysis technique are compared with those of the two reference particle analysis techniques: secondary ion mass spectrometry (SIMS) and fission track-thermo-ionization mass spectrometry (FT-TIMS), based on the measurement of the isotopic ratios of 235U/238U in particles present in an inter-comparison particulate sample. The agreement of the results obtained using LA-ICP-MS with target values and with the results obtained using FT-TIMS and SIMS was good. Accuracy was equivalent to that of the other two techniques (±3 % deviation). However, relative experimental uncertainties present with LA-ICP-MS (7 %) were higher than those present with FT-TIMS (4.5 %) and SIMS (3 %). Furthermore, measurement yield of LA-ICP-MS coupling was close to that obtained with the same quadrupole ICP-MS for the measurement of a liquid sample (~10?4), but lower than that obtained with FT-TIMS and SIMS, respectively, by a factor of 10 and 20, although the particles analyzed using LA-ICP-MS were most likely smaller (diameter ~0.6 μm, containing 4–7 fg of 235U). Nevertheless, thanks to the brevity of the signals obtained, the detection capacity for low isotopic concentrations by LA-ICP-MS coupling is equivalent to that of FT-TIMS, although it remains well below that of SIMS (×15). However, with more sensitive double focusing ICP-MS, performances equivalent to those achieved using SIMS could be obtained. 相似文献
150.
Amanda Emmanuelle Sales Fabiana América Silva Dantas de Souza José Antônio Teixeira Tatiana Souza Porto Ana Lúcia Figueiredo Porto 《Applied biochemistry and biotechnology》2013,170(7):1676-1688
Fibrinolytic proteases are enzymes that degrade fibrin; these enzymes are a promising alternative for thrombolytic therapy, and microorganisms produce them. The aim of this study was to evaluate the optimum conditions for the integrated production and purification of fibrinolytic protease from Bacillus sp. UFPEDA 485. Extractive fermentation was carried out in a culture medium containing soybean flour and by adding polyethylene glycol (PEG) and Na2SO4 according to a 23 experimental design. In all assays, the enzyme preferentially partitioned to the bottom phase (K?<?1), with an optimum activity of 835 U ml?1 in the bottom phase (salt-rich phase). The best conditions for extractive fermentation were obtained with 18 % PEG 8000 and 13 % Na2SO4. Characterization showed that it is a metalloprotease, as a strong inhibition—residual activity of 3.13 %—occurred in the presence of ethylenediaminetetraacetic acid. It was also observed that enzymatic activity was stimulated in the presence of ions: CaCl2 (440 %), MgCl2 (440 %), FeSO4 (268 %), and KCl (268 %). The obtained results indicate that the use of a low-cost substrate and the integration of fermentation with an aqueous two-phase system extraction may be an interesting alternative for the production of fibrinolytic protease. 相似文献