二苯醚两端苯环取向的量子化学研究

二苯醚两端苯环取向的量子化学研究＊叶世勇沈良骏（安徽师范大学化学系芜湖２４１０００）关键词二苯醚构象半经验量子化学方法主链含苯环的聚合物内苯环相对于主链角架面的取向与聚合物的某些力学性质如γ－松弛等直接有关。二苯醚是研究这类聚合物的一种有用的模型分子...     

Quantifying Western blots: Pitfalls of densitometry

Although Western blots are frequently quantified, densitometry is not documented and appears to be based merely on traditions and guesswork. Confirming previous experience, none of 100 randomly selected and systematically scanned most recent papers provided sufficient information on how Western blot results were translated into statistical values. The importance of such information, however, becomes evident from our correlations of plasma erythropoietin values of various mammals determined using RIA and Western blot densitometry. Different common densitometry procedures applied to the identical Western blot revealed p‐values of these correlations ranging from 0.000013 to 0.76 reflecting the necessity of a scientifically sound basis for densitometry of Western blots. At present, the current lack of any definitions in densitometry opens the door to uncontrollable acquisition of any desired p‐value. Here we provide data that define what should be considered, what avoided and what documented when quantifying Western blots.     

Free‐decomposability in varieties of semi‐Heyting algebras

In this paper we prove that the free algebras in a subvariety $\mathcal V$ of the variety $\mathcal {SH}$ of semi‐Heyting algebras are directly decomposable if and only if $\mathcal V$ satisfies the Stone identity.     

Birkhoff Centre of a Semi Group

The concept of the Birkhoff centre of a semi group with 0 and 1 was introduced by U.M. Swamy and G.S. Murti [3], analogous to that of a bounded Poset [1], and proved that it is a Boolean algebra. This concept was extended to a semi group with sufficiently many commuting idempotents in [2] by G.S. Murti and proved that it is a relatively complemented distributive lattice. In this paper, we extend the above concept for a general semi group S and prove that the Birkhoff centre of any semi group S is a relatively complemented distributive lattice.AMS Subject Classification (1991): 06A12, 20M10.     

半穿甲弹风帽气动特性分析

在半穿甲弹在敌方目标时,其弹头部的特殊穿甲形状可防止跳弹,但是在外弹道飞行时又会影响它的弹道性能。因此分析穿甲弹头部风帽对弹道的影响就至关重要。利用Fluent软件对半穿甲弹风帽进行外流场进行数值模拟,分析风帽表面流场分布,为风帽的外形设计而提供依据。     

基于图的半监督学习的距离度量改进

基于图的半监督学习的一个关键问题是：图上顶点之间的距离度量的有效性问题。为了解决这个问题,提出了基于图的半监督学习的距离度量改进方法。通过在现有密度敏感的距离度量方案中添加补偿参数的方法,使得改进的距离度量方案不但能够有效地扩大不同类别的高密度区域样本间的距离,同时还能缩小相同类别中样本之间的距离。将改进的距离度量方案应用到聚类算法中,来验证改进的距离度量方案的有效性。实验结果表明：改进的距离度量方法能够有效地扩大不同类别间距离,增强类内聚合度。     

Synthesis of novel 1,4-disubstituted-1,2,3-triazole semi synthetic analogues of forskolin by click reaction

New 1,4-disubstituted-1,2,3-triazole analogues of forskolin (5a-g, 6a-g) have been prepared by regioselective propargylation at 1-position followed by Cu(I) catalysed cycloaddition of different alkyl azides under the click reaction conditions. An interesting acyl shift in the base catalysed propargylation afforded a new series of 1,4-disubstituted-1,2,3-triazole analogues of forskolin (6a-g). These analogues have potential selective therapeutic applications as antihypertensive, antiglaucoma, antiasthma and antiobesity agents.     

推广的半绝对离差和动态投资组合选择

在标准的Black－Scholes型金融市场下，建立了以推广的半绝对离差（Extended Semi－Absolute Deviation；ESAD）度量风险的动态均值-ESAD投资组合选择模型，研究了模型的求解方法，得到了最优投资组合策略和均值-ESAD有效前沿的解析表达式．同时，与动态均值-方差模型作了比较分析．最后，结合实例说明了模型的求解方法．     

关于子群的两种广义正规性的注记

群 G 的一个子群 H 称为在 G 中具有半覆盖远离性,如果存在 G 的一个主群列1=G_0＜ G_1＜…＜G_1=G,使得对每一 i=1,…,l 或者 H 覆盖 G_j/G_(j-1)或者 H 远离 G_j/G_(j-1)．本文证明了予群的半覆盖远离性是子群 C-正规性和子群的覆盖远离性之推广．进一步应用极大子群和 Sylow 子群给出了有限群为可解群的一些特征．