增加采样保持器的记忆电压的取值范围

采样保持器应用于模数转换器之前。基本的采样保持电路由两个放大运算器（A1和A2）.     

Structural modeling of the pro-ocytocin-neurophysin precursor

The hormonal precursor pro-ocytocin-neurophysin is activated by selective cleavage at Arg2-Ala13, producing mature ocytocin and neurophysin. To understand the cleavage mechanism better, and in particular the recognition of the cleavage site, it is necessary to characterize the three-dimensional structure of the precursor molecule. Here we combine a variety of experimental data with molecular modeling and dynamics calculations to derive possible precursor conformations. In the models obtained, the N-terminus of the precursor, corresponding to the ocytocin segment, is hydrogen bonded in a pocket of the neurophysin moiety in a similar manner to a crystallographically obtained non-covalent complex between the two molecules. The calculations suggest that although the ocytocin segment is relatively flexible, it adopts a stable, broad loop structure in the vicinity of the cleavage region, which may constitute the structural element recognized by the cleaving enzyme. The calculations also suggest a possible widening of the distance between the two neurophysin domains in the precursor relative to that in the non-covalent neurophysin- ocytocin complex.      

Structural modeling of the pro-ocytocin-neurophysin precursor

This article reviews the information currently available on the pharmacoeconomic profile of taxanes in ovarian cancer. Because paclitaxel is the only taxene approved for this clinical indication, our overview is almost entirely focused on the cost-effectiveness profile of this drug. In advanced ovarian cancer, first-line regimens based on paclitaxel have been reported to be more effective than standard therapy based on cyclophosphamide + cisplatin. The improved survival with paclitaxel and the increased cost induced by this drug have prompted a series of pharmacoeconomic analyses, the results of which are summarized and discussed. Three studies, published between 1996 and 1997, calculated the cost per life-year gained using paclitaxel + cisplatin as opposed to cyclophosphamide + cisplatin. The estimates of survival gain and increased expenditure using paclitaxel were very similar; consequently, the results produced by these three analyses were homogeneous with values of cost per life-year gained around $20000. Because this value is below the conventional limit of $50000, the pharmacoeconomic results on paclitaxel suggest a favorable cost-effectiveness profile. Docetaxel is another taxane proposed for the treatment of advanced ovarian cancer; however, the drug has not yet been approved for this clinical indication and so a pharmacoeconomic assessment on this agent is still premature.     

增大运放输出电压范围的受控电源

增加IC运放的输出电压通常要增加大电压外接晶体管.然后形成的电路需要经过校正才能保持它的工作特性.这种校正是很困难的,尤其是对精密放大器而言.