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71.
Kalina Kostova Vladimir Dimitrov Svetlana Simova Manfred Hesse 《Helvetica chimica acta》1999,82(9):1385-1399
The allylic and homoallylic alcohols 1 – 8 , prepared from (+)-camphor and (−)-fenchone, were ozonized in Et2O at −78° and treated with Et3N or LiAlH4 to give the chiral hydroxy carbonyl compounds 9 – 16 and the diols 17 – 24 , respectively (Scheme 1). In the case of the diols 19 and 24 , the formation of new chiral centers proceeded with high diastereoselectivity. These diols were prepared highly diastereoselectively also by LiAlH4 reduction of the hydroxy carbonyl compounds 11 and 16a , respectively (Scheme 2). The absolute configuration of the new chiral centers in 19 and 24 was determined by X-ray and NMR methods. The ozonization of compounds 2 , 3 , 7 , and 8 provided the relatively stable hydroxy-substituted 1,2,4-trioxolane derivatives (ozonides) 37 – 40 (Scheme 5) which were characterized by 1H- and 13C-NMR spectra, ESI-MS, and natural-abundance 17O-NMR spectra. 相似文献
72.
Alt C Anticic T Baatar B Barna D Bartke J Betev L Białkowska H Billmeier A Blume C Boimska B Botje M Bracinik J Bramm R Brun R Buncić P Cerny V Christakoglou P Chvala O Cramer JG Csató P Darmenov N Dimitrov A Dinkelaker P Eckardt V Farantatos G Flierl D Fodor Z Foka P Freund P Friese V Gál J Gaździcki M Georgopoulos G Gładysz E Grebieszkow K Hegyi S Höhne C Kadija K Karev A Kliemant M Kniege S Kolesnikov VI Kollegger T Kornas E Korus R Kowalski M Kraus I Kreps M van Leeuwen M Lévai P Litov L 《Physical review letters》2005,94(19):192301
Results are presented on Omega production in central Pb+Pb collisions at 40 and 158A GeV beam energy. For the first time in heavy ion reactions, rapidity distributions and total yields were measured for the sum Omega(-) + Omega(+) at 40A GeV and for Omega(-) and Omega(+) separately at 158A GeV. The yields are strongly underpredicted by the string-hadronic UrQMD model but agree better with predictions from hadron gas models. 相似文献
73.
On Mg-containing Y zeolites toluene undergoes disproportionation and demethylation. The relative importance of the two processes is discussed.
Mg- Y . .相似文献
74.
75.
Sh. A. Syuleiman N. D. Yakushova I. A. Pronin N. V. Kaneva A. S. Bojinova K. I. Papazova M. N. Gancheva D. Tz. Dimitrov I. A. Averin E. I. Terukov V. A. Moshnikov 《Technical Physics》2017,62(11):1709-1713
A study of the photocatalytic activity of commercial and mechanically activated zinc oxide powders has been carried out based on the example of the decomposition of Brilliant Green. The goal of this work was to study the effect of the grinding time (0, 1, 3, 5, and 7 min) on the structure of zinc oxide and its photocatalytic activity under visible and ultraviolet (UV) radiation. It has been found that, when UV radiation is used, the constant of the dye oxidation rate for samples activated for 1 min increases compared with unactivated powders, whereas further mechanical activation leads to a decrease in the photocatalytic activity. When using visible radiation, samples activated for 1 min showed the minimum photocatalytic activity and further mechanical activation led to an increase in the efficiency of photocatalysis. 相似文献
76.
ZHU Sheng-Jiang J.H. Hamilton A.V. Ramayya J.K. Hwang J.O. Rasmussen Y. X. Luo K. Li WANG Jian-Guo CHE Xing-Lai DING Huai-Bo S. Frauendorf V. Dimitrov XU Qiang GU Long YANG Yun-Yi 《中国物理C(英文版)》2009,33(Z1)
High spin states in A ~ 110 neutron-rich 106Mo, 110Ru and 112Ru nuclei have been reinvestigated by measuring the prompt γ-rays from the spontaneous fission of 252Cf. Two similar sets of bands are observed to high spins in each of three nuclei. Through analyzing of characters of the band structures, the chiral doublet bands are suggested in 106Mo, 110Ru and 112Ru. 相似文献
77.
78.
Insulin is the only protein that is secreted in a crystalline form in a human healthy body. To mimic the secretion process we used NaCl salting‐out to growing tiny rhombohedral Zn‐insulin crystals. The dissolution of the insulin crystals is of special interest for the therapeutical praxis, because the human body is supplied with the physiologically active monomers of the insulin through dissolution of the crystalline granules secreted in the pancreatic β‐cells. Sets of tiny rhombohedral Zn‐insulin crystals, which resembled the granules secreted in the β‐cells, were subjected to dissolution in blood plasma and model solutions. The impacts of the solution composition, flow rate, pH and ionic strength on the insulin crystal dissolution were investigated. The effect of the blood plasma was determinant because it dissolved the rhombohedral Zn‐insulin crystals almost instantly, while the effects of solution's physicochemical characteristics were of minor importance. In addition, we found that the presence of abundant zinc ions suppressed the dissolution of the insulin crystals. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
79.
Dimitar K. Dimitrov Fernando R. Rafaeli 《Journal of Computational and Applied Mathematics》2009,233(3):699-702
Denote by xnk(α), k=1,…,n, the zeros of the Laguerre polynomial . We establish monotonicity with respect to the parameter α of certain functions involving xnk(α). As a consequence we obtain sharp upper bounds for the largest zero of . 相似文献
80.
Tsoncheva T Ivanova L Paneva D Dimitrov M Mitov I Stavrev S Minchev C 《Journal of colloid and interface science》2006,302(2):492-500
Nanosized diamond (UDD), obtained by a detonation procedure, was modified with iron from the corresponding acetylacetonate precursor under various pretreatment conditions. Nitrogen physisorption, X-ray diffraction, temperature-programmed reduction, and FTIR and M?ssbauer spectroscopy were used for their characterization. The samples' catalytic behavior in methanol decomposition was also studied. The physicochemical and catalytic properties of the obtained materials (Fe/UDD) were compared with those of other iron-oxide-modified mesoporous supports with different nature and functionality (MCM-48 silica and CMK-1 carbon). The highest catalytic activity and stability was achieved with air-pretreated Fe/UDD. 相似文献