超声光栅实验及其多普勒频移的一种简单研究方法

采用光子学方法,对超声光栅衍射实验和实验中出现的多普勒频移现象进行了研究,所得结论与采用光的波动性观点的惠更斯-菲涅耳原理及傅里叶变换等常规方法相同.该方法进一步加深了对衍射的本质和光的粒子性的理解并对光子的信息传递能力有初步的认识.     

Fuzzy矩阵方程的摄动问题

讨论了Fuzzy矩阵A的同解简化矩阵A^(2)，指出陈贻源论文《解Fuzzy关系方程》中定量3的错误。研究Fuzzy矩阵方程的摄动问题，解决了汤服成（2000）提出的未解决问题。     

Highly enantioselective hydrogenation of aromatic-heteroaromatic ketones

Asymmetric hydrogenation of ketone 1 using trans-RuCl(2)[(R)-xylbinap][(R)-daipen] (3) as a catalyst afforded secondary alcohol 2 quantitatively and in 99.4% ee. Further exploration of the effect of the thiazole ring substitution revealed that the catalyst was highly effective for the enantioselective hydrogenation of 5-benzoyl thiazoles, which afforded corresponding alcohols in 92-99% ee. The same protocol was applicable to a variety of aromatic-heteroaromatic ketones to generate secondary alcohols in excellent enantioselectivities. [reaction: see text]     

Palladium-catalyzed amidation of enol triflates: a new synthesis of enamides

[reaction: see text] The palladium-catalyzed coupling of a range of enol triflates with amides, carbamates, and sulfonamides has been developed. This offers a simple and widely applicable synthesis of enamides, which may not be readily available by other means.     

An investigation into causes and effects of high cyanide levels in the palladium-catalyzed cyanation reaction

[reaction: see text] The palladium-catalyzed cyanation reaction is known to be sensitive to dissolved cyanide. Investigation into some causes of high levels of dissolved cyanide is presented here, along with a robust solution to this problem.     

基于塔尔博特效应测量液体中的声速

通过移动凸透镜的纵向位置来调整像面上自成像级次,测得相邻2次自成像时凸透镜的距离,确定液体中的超声波长,再经计算给出声速,从而将类塔尔博特效应用于液体中声速的测量.给出了基于类塔尔博特效应的超声光栅测声速实验设计与验证,拓展了自成像技术的应用范围.     

Nucleophilic displacement at benzhydryl centers: asymmetric synthesis of 1,1-diarylalkyl derivatives

[reaction: see text] Activation of substituted 1,1-diarylmethanols as their corresponding toluenesulfonates and subsequent displacement with a range of carbon, nitrogen, oxygen, and sulfur nucleophiles proceeds in 81-96% yield. Enantiomerically enriched diarylmethanols 8a-c were activated and displaced with pyridine acetate enolate with complete stereochemical inversion at carbon to yield 1,1-diarylalkyl derivatives 10a-c without loss of optical purity.     

一些高碳富勒烯的光谱及HPLC特征

利用对叔本基杯「８」芳烃对烟炱中Ｃ６０的选择性配合作用 烟炱邻二氯苯（ＯＤＣＢ）提取筘的高碳成份得到富集,用高效液相色谱（ＨＰＬＣ）分离,得到Ｃ７０,Ｃ７６,Ｃ７８,Ｃ８４和五种高碳富勒烯及相应的ＵＶ－Ｖｉｓ光谱,实验中发现,ＯＤＣＢ提取物中Ｃ７８的比例与其它溶剂提取物略有差别,富勒烯的保留时间的对数与富勒烯的碳原子数之间的良好的线性关系,随着富勒烯对称性的降低,ＵＶ－Ｖｉｓ光谱吸收极值增多,谱带     

Effects of delayed recovery and nonuniform transmission on the spreading of diseases in complex networks

We investigate the effects of delaying the time to recovery (delayed recovery) and of nonuniform transmission on the propagation of diseases on structured populations. Through a mean-field approximation and large-scale numerical simulations, we find that postponing the transition from the infectious to the recovered states can largely reduce the epidemic threshold, therefore promoting the outbreak of epidemics. On the other hand, if we consider nonuniform transmission among individuals, the epidemic threshold increases, thus inhibiting the spreading process. When both mechanisms are at work, the latter might prevail, hence resulting in an increase of the epidemic threshold with respect to the standard case, in which both ingredients are absent. Our findings are of interest for a better understanding of how diseases propagate on structured populations and to a further design of efficient immunization strategies.     

隐变量交互作用分析建模及其在SAS上的实现

探讨隐变量交互作用分析的建模方法及其在SA S软件上的实现;首先阐述隐变量交互作用分析建模的原理,通过拟合一个隐变量交互作用分析示例,对加入交互作用项的统计分析结果与无交互作用项的统计分析结果进行对比;示例中交互作用项引起的变异在结果变量的总变异中占到79.20%.在应用结构方程模型分析隐变量产生的效应时,有时候不进行隐变量交互作用的分析可能会产生偏倚.