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981.
Design and synthesis of chiral Ti-1,1′-bi-2-naphthol coordination polymers for heterogeneous catalytic asymmetric oxidation of sulfides
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袁小亚 《重庆大学学报(英文版)》2008,(3)
Polymer-immobilized catalysis has many advantages such as easy recovery and reuse of catalyst. We prepared three novel chiral 1,1′-bi-2-naphthol-Ti coordination polymers with properly designed ligands and Ti(OiPr)4 under mild conditions. The prepared polymers exhibited good activity and excellent enantioselectivity (over 99%ee) in catalyzing the asymmetric oxidation of sulfides. The bridge linker in the polymer and the reaction solvent noticeably affected the enantioselectivity. The chiral coordination poly... 相似文献
982.
Sandra K. Faull 《Government Information Quarterly》1985,2(2):157-167
Many librarians affiliated with regional depositories are concerned about the ability of their libraries to receive, process, store, and service all the titles and series available on deposit from the Government Printing Office. Some of them have even questioned whether their library can maintain regional status and fulfill all the service elements specified in the Guidelines for the Depository Library System (1977). As this article demonstrates, regional librarians supported the concept of state plans because they believed that this process offered an excellent means to address their concerns. However, in only a few instances have the plans fulfilled the purpose which regional staff envisioned. Nonetheless, the foundation which they laid, if pursued and if the basic documentation underlying the depository program are rewritten, could lead to the type of changes sought by regional libraries. 相似文献
983.
The purpose of this study was to determine how female marathon runners of varying standards differed in body composition and physique and in their training regimes, and secondly to develop predictors of distance running performance from the anthropometric and training variables. Female marathon runners (n = 36), all participants in a national 10 mile (16 km) road racing championship, were divided into three groups according to their best time for the 26.2 mile race. They were assessed for body composition and somatotype using anthropometric techniques and completed a questionnaire about their current training for the marathon. No difference was found between the groups of distance runners when measured for height, bone widths and circumferences. The three groups were found to have similar body weights of approximately 53 kg, a value which is much lower than the average for sedentary women, but which compares favourably with those from previous studies of female long distance runners. While all the runners had a lower per cent fat, as measured from skinfold thicknesses, than sedentary women, the elite runners were seen to have significantly lower values (P less than 0.05) than the other two groups. The difference in body fat was particularly reflected in the triceps skinfold value. There was also a tendency for the elite runners to be more ectomorphic and less endomorphic than the others. The better runners were seen, on the whole, to have been running longer, and to have more strenuous regimes, both in terms of intensity of training and distance run per week. Multiple regression and discriminant function analyses indicated that the number of training sessions per week and the number of years training were the best predictors of competitive performance at both 10 mile and marathon distances. They also indicated that a female long distance runner with a slim physique high in ectomorphy has the greatest potential for success. 相似文献
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