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981.
Johannes G. de Vries 《复旦学报(自然科学版)》2005,44(5)
1Introduction
In custom manufacturing time-to-market is of overriding importance. Thus, asymmetric hydrogenation will be applied only if an appropriate catalyst can be found in a very short period of time. For this reason we have build up a full-scale capability for High Throughput Experimentation, encompassing several robot systems. As ligand synthesis was the last remaining barrier we have explored, together with the University of Groningen, the use of simple monodentate ligands, such as MonoPhosTM. These ligands can be synthesised in two chemical steps, from BINOL, PCl3 and an amine.Surprisingly, very high enantioselectivities can be obtained in the asymmetric hydrogenation of α-and β-dehydro-amino acids and esters, aromatic enamides, itaconic acid and ester[1]. See Scheme 1 and 2(at page 830). 相似文献
982.
Insulin is necessary to produce an increase of plasma fibrinogen in rats submitted to tissue injury or ACTH administration. This increase is more significant when endogenous or exogenous excess of insulin is present, while in uninjured rats the absence or excess insulin does not modify plasma fibrinogen. 相似文献
983.
Jeroen de Ridder 《Studies in history and philosophy of science》2006,37(1):81-96
One thing about technical artefacts that needs to be explained is how their physical make-up, or structure, enables them to fulfil the behaviour associated with their function, or, more colloquially, how they work. In this paper I develop an account of such explanations based on the familiar notion of mechanistic explanation. To accomplish this, I (1) outline two explanatory strategies that provide two different types of insight into an artefact’s functioning, and (2) show how human action inevitably plays a role in artefact explanation. I then use my own account to criticize other recent work on mechanistic explanation and conclude with some general implications for the philosophy of explanation. 相似文献
984.
施群德 《山东科技大学学报(自然科学版)》2000,19(3):104-107
论述了改进自由动态子结构方法,并通过对十层井塔的分析计算,论述了该方法的适用条件及优越性。 相似文献
985.
针对湿法同时脱硫脱硝工艺 ,提出通过构造一个液相反应过程 ,将 NOx 和 SO2 溶解在溶液中生成的 NO2 -2 和 SO2 -3 经过一系列连续的液相离子反应生成有利用价值的 NH+4 ,实现资源的合理利用。在 35°C~ 74°C,离子强度为 0 .5 5 mol/L时对羟胺二磺酸钾磺化反应动力学进行了研究 ,得出反应的动力学方程为 :- dcHIDSdt =kc HON( SO3) 2 -2 · c HSO-3,其中 k=5 .5 0 9× 1 0 8· e-6.154× 10 4 / RT;在5 0°C、离子强度为 0 .31 mol/L~ 0 .65 mol/L时 ,研究了该反应的盐效应 ,结果表明该反应呈负盐效应 ,离子强度为零时 ,有最大的速率常数 k0 =0 .0 2 4 7L /( mol· min) 相似文献
986.
Jackie S Bodnar Aurobindo Chatterjee Lawrence W Castellani David A Ross Jeffrey Ohmen James Cavalcoli Chenyan Wu Katherine M Dains Joe Catanese Michael Chu Sonal S Sheth Kanti Charugundla Peter Demant David B West Pieter de Jong Aldons J Lusis 《Nature genetics》2002,30(1):110-116
Familial combined hyperlipidemia (FCHL, MIM-144250) is a common, multifactorial and heterogeneous dyslipidemia predisposing to premature coronary artery disease and characterized by elevated plasma triglycerides, cholesterol, or both. We identified a mutant mouse strain, HcB-19/Dem (HcB-19), that shares features with FCHL, including hypertriglyceridemia, hypercholesterolemia, elevated plasma apolipoprotein B and increased secretion of triglyceride-rich lipoproteins. The hyperlipidemia results from spontaneous mutation at a locus, Hyplip1, on distal mouse chromosome 3 in a region syntenic with a 1q21-q23 FCHL locus identified in Finnish, German, Chinese and US families. We fine-mapped Hyplip1 to roughly 160 kb, constructed a BAC contig and sequenced overlapping BACs to identify 13 candidate genes. We found substantially decreased mRNA expression for thioredoxin interacting protein (Txnip). Sequencing of the critical region revealed a Txnip nonsense mutation in HcB-19 that is absent in its normolipidemic parental strains. Txnip encodes a cytoplasmic protein that binds and inhibits thioredoxin, a major regulator of cellular redox state. The mutant mice have decreased CO2 production but increased ketone body synthesis, suggesting that altered redox status down-regulates the citric-acid cycle, sparing fatty acids for triglyceride and ketone body production. These results reveal a new pathway of potential clinical significance that contributes to plasma lipid metabolism. 相似文献
987.
Harmse Marthi Pothas Anne-Marié de Wet Andries G. 《Systemic Practice and Action Research》2002,15(1):37-49
This paper discusses an application of the CRASP model of Action Research (AR) on Operations Research (OR). The CRASP model portrays AR as a style of staff development that would lead to professionalism. It also advocates social responsibility, committed and informed action, and a critical approach. All of these concerns are inherent to the process of reflection and development characteristic of OR. As an OR practitioner I participate in this process of reflection and development and applied the CRASP model of AR in performing one application novel to OR, namely, OR for street children. Reflecting on this application of AR on OR for street children, some similarities between AR and OR surface, as well as some difficulties in applying AR on OR, thereby enriching both AR and OR. It is hoped that through collaborative reflection with other AR and OR practitioners, this paper will further our professional development. 相似文献
988.
989.
Inhaled allergens from house dust, mites or animal danders activate human complement in vitro by engaging the C1-component
through a non-antibody-dependent mechanism. These earlier findings are extended by showing that the allergenic components
in extracts of Parietaria pollen are almost equally potent complement activators as those from house dust or mites. Spectroscopic evidence indicates
that haemolytic complement consumption by the Parietaria allergens and their enzymic fragments is most likely related to post-translational side-chains comprising flavonoid derivatives.
These adsorbed and/or peptide-bound tannin-like structures may also explain the exceptional stability of the high- and low-molecular
mass allergenic components in Parietaria pollen extracts.
Received 12 November 1996; received after revision 12 December 1996; accepted 17 December 1996 相似文献
990.
Rotation in Correspondence Analysis 总被引:1,自引:1,他引:0
In correspondence analysis rows and columns of a nonnegative data matrix are
depicted as points in a, usually, two-dimensional plot. Although such a two-dimensional
plot often provides a reasonable approximation, the situation can occur that an approximation
of higher dimensionality is required. This is especially the case when the data
matrix is large. In such instances it may become difficult to interpret the solution. Similar
to what is done in principal component analysis and factor analysis the correspondence
analysis solution can be rotated to increase the interpretability. However, due to the various
scaling options encountered in correspondence analysis, there are several alternative
options for rotating the solutions. In this paper we consider two options for rotation in
correspondence analysis. An example is provided so that the benefits of rotation become
apparent. 相似文献