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51.
JPC – Journal of Planar Chromatography – Modern TLC - The discovery of the implication of free radicals in the etiology of many diseases has led to increased interest in functional food... 相似文献
52.
Liana Marta Lelia Ciontea T. Petrisor Maria Zaharescu D. Crisan Iovanca Haiduc 《Journal of Sol-Gel Science and Technology》1994,2(1-3):437-441
Bismuth high T
c superconducting oxide compounds were obtained by sol-gel method using acetate precursors. A study of the decomposition of quasi-amorphous acetates has been carried out to establish the conditions of superconducting phase formation. A comparison of the acetate sol-gel route with the oxalate coprecipitation method (previously used by the authors) reveals comparable results. Both methods require much shorter periods of thermal treatment for the formation of superconducting phases, as compared with the solid state reactions. The sol-gel route leads to better results from this point of view. 相似文献
53.
Socaciu LD Hagen J Le Roux J Popolan D Bernhardt TM Woste L Vajda S 《The Journal of chemical physics》2004,120(5):2078-2081
Reactions of free silver anions Agn- (n = 1 - 13) with O2, CO, and their mixtures are investigated in a temperature controlled radio frequency ion trap setup. Cluster anions Agn- (n = 1 - 11) readily react with molecular oxygen to yield AgnOm- (m = 2, 4, or 6) oxide products. In contrast, no reaction of the silver cluster anions with carbon monoxide is detected. However, if silver cluster anions are exposed to the mixture of O2 and CO, new reaction products and a pronounced, discontinuous size dependence in the reaction behavior is observed. In particular, coadsorption complexes Agn(CO)O2- are detected for cluster sizes with n = 4 and 6 and, the most striking observation, in the case of the larger odd atom number clusters Ag7-, Ag9-, and Ag11-, the oxide product concentration decreases while a reappearance of the bare metal cluster signal is observed. This leads to the conclusion that carbon monoxide reacts with the activated oxygen on these silver clusters and indicates the prevalence of a catalytic reaction cycle. 相似文献
54.
Ghizdavu L Lentzen O Schumm S Brodkorb A Moucheron C Kirsch-de Mesmaeker A 《Inorganic chemistry》2003,42(6):1935-1944
The optically active cyclometalated Rh(III) complexes, delta[Rh(thpy4,5p(R,R)py)(2)TAP]Cl, lambda[Rh(thpy4,5p(S,S)py)(2)TAP]Cl, and delta[Rh(phpy4,5p(R,R)py)(2)TAP]Cl (where TAP = 1,4,5,8-tetraazaphenanthrene, thpy4,5p(R,R)py = (8R,10R)-2-(2'-thienyl)-4,5-pinenopyridine and phpy4,5p(R,R)py = (8R,10R)-2-(2'-phenyl)-4,5-pinenopyridine) have been prepared and characterized. Their photophysics has been examined in parallel with that of rac[Rh(thpy)(2)TAP]Cl and rac[Rh(phpy)(2)TAP]Cl. Their behaviors have been rationalized from results of TD-DFT calculations. The complexes with thienylpyridine (thpy) as cyclometalating ligands exhibit (3)CT (from thpy to TAP) and (3)LC(pi-pi) (centered on thpy) emissions in a solvent matrix at 77 K and one (3)CT luminescence at room temperature. In contrast, with phenylpyridine (phpy), the complexes show only one (3)CT emission (from phpy to TAP) at both temperatures. 相似文献
55.
We study diophantine properties of a typical point with respect to measures on
\mathbbRn .\mathbb{R}^n . Namely, we identify geometric conditions on a measure μ on
\mathbbRn \mathbb{R}^n guaranteeing that μ-almost every
y ? \mathbbRn {\bf y}\,\in\,\mathbb{R}^n is not very well multiplicatively approximable by rationals. Measures satisfying our conditions are called ‘friendly’. Examples
include smooth measures on nondegenerate manifolds; thus this paper generalizes the main result of [KM]. Another class of
examples is given by measures supported on self-similar sets satisfying the open set condition, as well as their products
and pushforwards by certain smooth maps. 相似文献
56.
57.
58.
Sumeet K. Sharma Simon D. BishoppC. Liana Allen Ruth LawrenceMark J. Bamford Alexei A. LapkinPawel Plucinski Robert J. WatsonJonathan M.J. Williams 《Tetrahedron letters》2011,52(33):4252-4255
The atom-efficient and cost-effective rearrangement of oximes into primary amides is catalyzed by simple copper salts. The use of homogeneous Cu(OAc)2 (1-2 mol %) was found to be effective for this transformation at 80 °C. The reaction was successful with either conventional or microwave heating. CuO and CuO/ZnO on activated carbon provided a competent reuseable heterogeneous catalyst which could be used in a batch process or in flow. Copper salts are much cheaper than the precious metals previously used for this rearrangement, and the reaction conditions are milder than those reported. 相似文献
59.
Palash Jyoti Das Anil Barak Yusuke Kawakami Tharanikkarasu Kannan 《Journal of polymer science. Part A, Polymer chemistry》2011,49(6):1376-1386
ABA‐type amphiphilic tri‐block copolymers were successfully synthesized from poly(ethylene oxide) derivatives through anionic polymerization. When poly(styrene) anions were reacted with telechelic bromine‐terminated poly(ethylene oxide) ( 1 ) in 2:1 mole ratio, poly(styrene)‐b‐poly(ethylene oxide)‐b‐poly(styrene) tri‐block copolymers were formed. Similarly, stable telechelic carbanion‐terminated poly(ethylene oxide), prepared from 1,1‐diphenylethylene‐terminated poly (ethylene oxide) ( 2 ) and sec‐BuLi, was also used to polymerize styrene and methyl methacrylate separately, as a result, poly (styrene)‐b‐poly(ethylene oxide)‐b‐poly(styrene) and poly (methyl methacrylate)‐b‐poly(ethylene oxide)‐b‐poly(methyl methacrylate) tri‐block copolymers were formed respectively. All these tri‐block copolymers and poly(ethylene oxide) derivatives, 1 and 2 , were characterized by spectroscopic, calorimetric, and chromatographic techniques. Theoretical molecular weights of the tri‐block copolymers were found to be similar to the experimental molecular weights, and narrow polydispersity index was observed for all the tri‐block copolymers. Differential scanning calorimetric studies confirmed the presence of glass transition temperatures of poly(ethylene oxide), poly(styrene), and poly(methyl methacrylate) blocks in the tri‐block copolymers. Poly(styrene)‐b‐poly(ethylene oxide)‐b‐poly(styrene) tri‐block copolymers, prepared from polystyryl anion and 1 , were successfully used to prepare micelles, and according to the transmission electron microscopy and dynamic light scattering results, the micelles were spherical in shape with mean average diameter of 106 ± 5 nm. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
60.
Time‐resolved luminescence properties of Ce3+ doped Y3Al5O12 (YAG) nanocrystals have been studied by means of vacuum‐ultraviolet excitation spectroscopy. It was discovered that additionally to the regular Ce3+ yellow‐green emission which is well‐known luminescence in YAG, new emission covering a broad spectral range from 2.7 eV to 3.5 eV was revealed in the luminescence spectra for all YAG:Ce nanocrystals studied. This blue‐UV emission has fast decay time about 7 ns as well as intensive well‐resolved excitation band peaking at 5.9 eV and, in contrast to green Ce3+ emission, practically is not excited at higher energies. The origin of the blue‐UV emission is tentatively suggested and discussed. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献