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131.
5-Amino-2,3,6,7-tetrahydrothiocines were reacted with arylazides yielding 1-aryl-9a-amino-1,3a,4,5,7,8,9,9a-octahydrothiocino[4,5-d]-1,2,3-triazoles which could be deaminated to 1-aryl-1,4,5,7,8,9-hexahydrothiocino-[4,5-d]-1,2,3-triazoles. Similarly, the above enamines yielded, with nitrile oxides, 3-aryl-9a-amino-3a,4,5,8,9,9a-hexahydrothiocino[4,5-d]isoxazoles which were transformed with acids into 3-aril-4,5,8,9-tetrahydrothiocino-[4,5-d]isoxazoles. 相似文献
132.
This paper introduces a new memetic algorithm specialized for the asymmetric instances of the traveling salesman problem (ATSP). The method incorporates a new local search engine and many other features that contribute to its effectiveness, such as: (i) the topological organization of the population as a complete ternary tree with thirteen nodes; (ii) the hierarchical organization of the population in overlapping clusters leading to the special selection scheme; (iii) efficient data structures. Computational experiments are conducted on all ATSP instances available in the TSPLIB, and on a set of larger asymmetric instances with known optimal solutions. The comparisons show that the results obtained by our method compare favorably with those obtained by several other algorithms recently proposed for the ATSP. 相似文献
133.
Emerson A. dos Santos Luciana R.P. Kassab Niklaus U. Wetter Sidney J.L. Ribeiro 《Journal of luminescence》2007,124(2):200-206
A simulation of erbium-doped glass systems, which provides population density for the excited states involved in the 1.5 μm and also for 2.7 μm emissions when pumped around 980 nm, is presented. To describe the diode pump laser processes, a theoretical model based in a coupled system of differential rate equations was developed. The approach used and the obtained spectroscopic parameters are discussed. The materials under study are two oxide glasses, lead fluoroborate (PbO-PbF2-B2O3), and heavy metal oxide (Bi2O3-PbO-Ga2O3) and a fluoride glass (ZrF4-BaF2-LaF3-AlF3-NaF), all of them doped with Er3+. 相似文献
134.
The optical properties of binary and ternary germanate glasses 40.3GeO2-59.7PbO, 31.3GeO2-26.8PbO-41.9Bi2O3 and 31.5GeO2-40.4PbO-28.1Bi2O3 (wt%) doped with Er3+ were investigated. The Judd-Ofelt intensity parameters were calculated and the near-infrared luminescence as well as the upconversion efficiency was analyzed. We observed that the ternary germanate glass containing the highest concentration of Bi2O3 presented the largest emission bandwidth for 4I13/2 → 4I15/2 transition and the highest infrared-to-visible upconversion efficiency among the samples studied. These results demonstrate that not only the presence of Bi2O3 but also the careful choice of its molecular weight plays a key role in optimizing parameters for using germanate glasses for photonics applications. 相似文献
135.
Carlo Anchisi Luciana Corda Anna Fadda Antonio Maccioni Gianni Podda 《Journal of heterocyclic chemistry》1982,19(3):649-652
The cleavage reaction of some 1,3,2-benzoxathiastannole, -arsole and -stibole derivatives with acetyl and benzoyl chloride is described. The reactions were carried out refluxing in benzene or at room temperature. In all cases, the reaction occurs through the initial cleavage of the S-M linkage with formation of the respective o-acylthio derivatives. The structure of the prepared compounds was assigned on the basis of their analytical, physical and spectral data. 相似文献
136.
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138.
[reaction: see text] Initial efforts toward the total synthesis of the antifungal antibiotics spirofungins A and B are reported. A short and efficient synthesis of the C9-C20 6,6-spiroketal fragments of both compounds is described. This asymmetric approach uses a very efficient alkylation of a lithiated N,N-dimethylhydrazone followed by spiroketal formation under acidic conditions. 相似文献
139.
The ammonium removal efficiency (ARE) and cell viability was investigated in freshly isolated rat hepatocytes exposed to increasing ammonium loads (0.1-2.0 mM). No difference was observed in both ARE and cell viability at the different ammonium concentrations tested. Storage of hepatocytes at 0 degrees C for 72 hours inhibited ammonium removal and urea synthesis. Rewarming of cells at 37 degrees C for 120 min was followed by an ARE fully comparable to freshly isolated hepatocytes. These data indicated that cold preservation of rat hepatocytes for 3 days in UW followed by a rewarming is associated with normal ammonium detoxification efficiency. 相似文献
140.
We devised a simple method for determining the cryoprotectant agents 1,4-butanediol or 2,3-butanediol in isolated rat hepatocytes. After extraction of of hepatocytes with water (containing internal standard - ethylene glycol 1.25 mg/mL) the diol content was analyzed by gas chromatography. The method shows a linear response in the range 0.125 to 2.50 mg/mL for 1,4-butanediol and 0.25 to 3.75 mg/mL for 2,3-butanediol. The accuracy and precision of the method were evaluated and the coefficients of variation were found to be within = 6.0 %. The recoveries from hepatocyte samples containing 0.50, 1.00 and 2.00 mg/mL were 91.0 to 108 % for 1,4-butanediol and 80.6 to 100.3 % for 2,3-butanediol, respectively. This method allowed the determination of the intracellular concentration of diols in hepatocytes preserved for up to 120 hours at - 4 (C in UW solution + 8 % w/v 1,4-butanediol (or 2,3-butanediol). 相似文献