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排序方式: 共有113条查询结果,搜索用时 15 毫秒
91.
92.
Scott P. DraffinPeter J. Duggan Sandhya A.M. DugganJens Chr. Norrild 《Tetrahedron》2003,59(46):9075-9082
The transport of fructose and glucose through supported liquid membranes promoted by a tetrahedral shaped lipophilic monoboronic acid and diboronic acid, both based on a pentaerythritol core, has been studied. The diboronic acid gave a high fructose/glucose selectivity (7.7:1.0). The results of molecular modelling studies and 13C NMR experiments with uniformly labelled 13C-d-fructose suggest that the enhanced selectivity results from the formation of a trisdentate 2,3,6-β-d-fructofuranose diester within the membrane. Experimental evidence for a previously proposed macrocyclic d-fructopyranose diester formed with an o-phenylene linked diboronic acid has also been found. 相似文献
93.
Live virtual machine migration can have a major impact on how a cloud system performs, as it consumes significant amount of network resources, such as bandwidth. A virtual machine migration occurs when a host becomes over-utilised or under-utilised. In this paper, we propose a network aware live migration strategy that monitors the current demand level of bandwidth when network congestion occurs and performs appropriate actions based on what it is experiencing. The Artificial Intelligence technique that is based on Reinforcement Learning acts as a decision support system, enabling an agent to learn an optimal time to schedule a virtual machine migration depending on the current bandwidth usage in a data centre. We show from our results that an autonomous agent can learn to utilise available network resources such as bandwidth when network saturation occurs at peak times. 相似文献
94.
Fitzhenry Laurence Manesiotis Panagiotis Duggan Patrick McLoughlin Peter 《Mikrochimica acta》2013,180(15):1421-1431
Microchimica Acta - A comparative study was performed on different polymeric formats for targeting corticosteroids, focusing on the use of bulk monolith and precipitation polymerisation strategies.... 相似文献
95.
F. D. McDaniel S. Matteson J. M. Anthony D. L. Weathers J. L. Duggan D. K. Marble I. Hassan Z. Y. Zhao A. M. Arrale Y. D. Kim 《Journal of Radioanalytical and Nuclear Chemistry》1993,167(2):423-432
An Accelerator Mass Spectrometry (AMS) facility has been assembled at the University of North Texas (UNT) in collaboration with Texas Instruments, Inc. The UNT AMS facility is used primarily for the high sensitivity determination of trace elements of stable isotopes in materials. Particle accelerators, in conjunction with magnetic (momentum/charge) and electrostatic (energy/charge) spectrometers and particle energy detectors, may be used to measure rare isotopes at concentrations as low as one part in 1012 or 1010 atoms/cm3. 相似文献
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Carreno MC Garcia Ruano JL Urbano A Remor CZ Arroyo Y 《The Journal of organic chemistry》2000,65(2):453-458
Diels-Alder reactions of (SS)-2-(2'-methoxynaphthylsulfinyl)-1, 4-benzoquinone (1b), 2-(p-methoxyphenylsulfinyl)-1,4-benzoquinone (1c), and 2-(p-nitrophenylsulfinyl)-1,4-benzoquinone (1d) with cyclopentadiene are reported. These cycloadditions allowed the highly chemo- and stereoselective formation of both diastereoisomeric endo-adducts resulting from reaction on the unsubstituted double bond C(5)-C(6) of quinones working under thermal and Eu(fod)(3)- or BF(3).OEt(2)-catalyzed conditions. The synthesis of endo-adduct [4aS,5S,8R,8aR,SS]-9d resulting from cycloaddition on the substituted C(2)-C(3) double bond was achieved in a chemo- and diastereoselective way from quinone 1d in the presence of ZnBr(2). The reactivity and selectivity of the process proved to be dependent on the electron density of the arylsulfinyl group. 相似文献
99.
Garcia Ruano JL Barros D Maestro MC Slawin AM Page PC 《The Journal of organic chemistry》2000,65(19):6027-6034
The asymmetric aldol reaction of 1,2-diketones, masked as nonracemic 2-acyl dithiane oxides, with lithium enolates derived from several esters and lactones, proceeds with a high degree of stereocontrol at both carbonyl and enolate prochiral centers, the stereocontrol mainly determined by the configuration of the sulfoxide sulfur atom. The sense of induced stereochemistry observed for ester enolates is different from that seen for lactone enolates. Hydrolysis of the dithiane oxide units of the major diastereoisomerically pure aldol products affords enantiomerically pure tertiary alpha-substituted beta-hydroxy-gamma-ketoesters. 相似文献
100.