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31.
2,6-Diacetylpyridine bis(benzoylhydrazone) (H2DPBH) is proposed as a ligand for the extraction of uranium(VI). Complete extraction from aqueous solutions into dichloromethane is achieved with a ligand/metal mole ratio of < for 10?5?10?4 M uranyl ion. Potentiometric measurements indicate that the extracted species is UO2 (DPBH). Uranium can be determined in the extract by spectrophotometric measurements at 420 nm and by differentail pulse polarography (Ep = ?0.67 V) with tetraethylammonium bromide as supporting electrolyte. For both methods, the detection limit is about 2 × 10?6 M in the extract. 相似文献
32.
Lucia D'Accolti Cosimo Annese Antonella Aresta Caterina Fusco 《Journal of heterocyclic chemistry》2014,51(5):1482-1486
Epoxides are essential building blocks in organic chemistry. The epoxidation of unsubstituted cyclic dienes 2 , 3 , 4 and triene 5 using dimethyldioxirane ( 1a ) and its trifluoro analog 1b methyl(trifluoromethyl)dioxirane has been investigated. The excellent yields obtained (90–98%) are accompanied by outstandingly high diastereoselectivities (90–98%). Interpretation of results based upon the early idea that polar groups can direct the dioxirane attack by dipole–dipole interaction provides a likely rationale, along with a more generalized mechanistic view. 相似文献
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Antonella Marini Thomas H. Otway 《Annales de l'Institut Henri Poincaré (C) Analyse Non Linéaire》2014
Duality methods are used to generate explicit solutions to nonlinear Hodge systems, demonstrate the well-posedness of boundary value problems, and reveal, via the Hodge–Bäcklund transformation, underlying symmetries among superficially different forms of the equations. 相似文献
35.
Giuseppe Leone Antonella Caterina Boccia Giovanni Ricci Antonino Giarrusso Lido Porri 《Journal of polymer science. Part A, Polymer chemistry》2013,51(15):3227-3232
(E)‐1,3‐Pentadiene (EP) and (E)‐2‐methyl‐1,3‐pentadiene (2MP) were polymerized to cis‐1,4 polymers with homogeneous and heterogeneous neodymium catalysts to examine the influence of the physical state of the catalyst on the polymerization stereoselectivity. Data on the polymerization of (E)‐1,3‐hexadiene (EH) are also reported. EP and EH gave cis‐1,4 isotactic polymers both with the homogeneous and with the heterogeneous system, whereas 2MP gave an isotactic cis‐1,4 polymer with the heterogeneous catalyst and a syndiotactic cis‐1,4 polymer, never reported earlier, with the homogeneous one. For comparison, the results obtained with the soluble CpTiCl3‐based catalyst (Cp = cyclopentadienyl), which gives cis‐1,4 isotactic poly(2MP), are examined. A tentative interpretation is given for the mechanism of the formation of the stereoregular polymers obtained and a complete NMR characterization of the cis‐1,4‐syndiotactic poly(2MP) is reported. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3227–3232 相似文献
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Dr. Jana Franke Dr. Martin Bock Dr. Richard Dehn Dr. Jörg Fohrer Dr. Santosh B. Mhaske Dr. Antonella Migliorini Dr. Argyrios A. Kanakis Dr. Rolf Jansen Dr. Jennifer Herrmann Prof. Dr. Rolf Müller Prof. Dr. Andreas Kirschning 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(11):4272-4284
The total and semi‐synthesis of 13 new macrolactones derived from thuggacin, which is a secondary metabolite from the myxobacterium Sorangium cellulosum, are reported. The thuggacins have attracted much attention due to their strong antibacterial activity, particularly towards Mycobacterium tuberculosis. This study focuses on 1) thuggacin derivatives that cannot equilibrate by transacylation between the three natural thuggacins A–C, 2) the roles of the thiazole ring, and 3) the hexyl side chain at C2. Semi‐synthetic O‐methylation at C17 suppressed the transacylations without a substantial loss of antibacterial activity. Exchanging the C17–C25 side chain for simplified hydrophobic chains led to complete loss of antibacterial activity. Exchange of the thiazole by an oxazole ring or removal of the hexyl side chain at C2 had no substantial effect on the biological properties. 相似文献
38.
Plaia Antonella Sciandra Mariangela 《Advances in Data Analysis and Classification》2019,13(2):427-444
Advances in Data Analysis and Classification - Within the framework of preference rankings, the interest can lie in finding which predictors and which interactions are able to explain the observed... 相似文献
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