硼烷体系中(S)-吲哚醇或(S)-吲哚酸催化的前手性酮的不对称还原

直接应用非修饰的简单氨基醇和氨基酸((S)-吲哚醇或(S)-吲哚酸)在硼烷体系中催化前手性酮进行不对称还原。通过反应条件的优化,大大增强了手性催化剂的催化能力,产物手性二级醇的e.e.值可以达到82%～82%,与文献报道的结果相比有了很大的提高。     

廉价原料制备钛硅沸石

采用Ｔｉ＾４＋同晶取代Ｓｉ＾４＋的气固相取代法及水热晶化法制备了钛硅沸石（ＴＳ－１）,＾１Ｈ→＾１３ＣＣＰ／ＭＡＳＮＭＲ谱的研究结果表明,水热晶化法合成时,可用ＴＰＡＢｒ（四丙基溴化铵）代替ＴＰＡＯＨ（四丙基氢氧化铵）,并可把ｎ（ＴＰＡ＾＋）／ｎ（ＳｉＯ２）降至０．０５;     

rojected structure of uroplakins in urothelium of rabbit urinary bladder at 20 A resolution

Asymmetric unit membrane (AUM) was isolated and purified from the urothelium of rabbit urinary bladder. The electron micrographs were taken from negatively stained AUM patches. The Fourier filtering and lattice distortion correction were carried out by a computer. The projected structure of uroplakins in asymmetric unit membrane of rabbit urothelium at 20 A resolution was obtained.     

Strategic asset allocation by mixing shrinkage,vine copula and market equilibrium

We propose a new portfolio optimization method combining the merits of the shrinkage estimation, vine copula structure, and Black–Litterman model. It is useful for many investors to satisfy simultaneously the three investment objectives: estimation sensitivity, asymmetric risks appreciation, and portfolio stability. A typical investor with such objectives is a sovereign wealth fund (SWF). We use China's SWF as an example to empirically test the method based on a 15‐asset strategic asset allocation problem. Robustness tests using subsamples not only show the method's overall effectiveness but also manifest that the function of each component is as expected.     

信息不对称条件下的辅导员激励机制研究

国内目前的辅导员激励研究一般假设学校与辅导员之间的信息是对称的,辅导员的努力程度能够被观察到,这与现实情况不符。文章运用多任务委托——代理模型,分析辅导员在现行激励机制下的行为选择,并根据结论对辅导员激励机制提出建议：选聘合适对象,加强新辅导员的＂期望管理＂;设计科学的考评制度,引导辅导员合理地对待各项工作;重视过程监督,提高学生评价的权重;严格执行考评办法,将考评结果与薪酬水平挂钩。     

非对称线型体外预应力梁自振频率特性分析

体外预应力技术在结构加固等方面具有独特的应用优势.为了全面分析体外索各种线型布置下体外预应力梁的动力性能,运用结构动力学知识给出了较为精确的体外索非对称线型布置的体外预应力简支梁自振频率计算公式.Ayaho Miyamoto等人给出的只适用于体外索对称线型布置的体外预应力梁自振频率计算公式在取相应的对称线型系数时,经验算,与其是一致的,因此体外预应力自振频率计算公式得以修正和扩充.     

聚苯乙烯/聚吡咯复合微球催化剂性能

采用种子乳液聚合制备了聚苯乙烯/聚吡咯(PS/PPY)复合微球,以其为载体负载钼活性中心制备了PS/PPY复合微球负载钼系催化剂,系统研究了载体性质对负载型催化剂催化环辛烯环氧化反应的催化活性.结果表明:亲水性的负载型催化剂在以过氧化氢为氧源的催化体系中催化活性较高;聚合物的掺杂离子对催化剂的催化性能具有重要影响,以硝酸铁为氧化剂制备的负载型催化剂的催化活性最高,催化环辛烯环氧化的转化率可以达到90%.     

Asymmetric energy flow in coupled nonlinear LC transmission line

We constructed a coupled LC transmission line and studied the propagation of waves in it. We found asymmetric energy flow when we changed the driving conditions at the boundary. We analyzed this change and believe that it occurs because of the bandpass characteristics of the LC transmission line and high-order harmonic waves induced by nonlinearities. The LC transmission line could be used to simulate a microscopic crystal lattice. Therefore, we hope to observe thermal rectification in the system. We investigated the dependence of the system on different parameters, and then discussed the multi-frequency condition to aid in experimental verification.     

Micro-particle deposition and lobar distribution of mass flow in human upper respiratory tract model

A representative human upper respiratory tract model consisting of oropharyngeal and asymmetric tracheobronchial(TB) airways from the trachea(G0) to the main lobar bronchi(G2) was constructed. Laminar-to-turbulent airflow for typical inhalation modes as well as micro-particle transportation,wall deposition and mass flow to lobes was simulated using the CFX10.0 software from Ansys Inc. The numerical particle deposition efficiency of the oropharynx region and two generations(G1 and G2) of TB airways shows gre...     

新型樟脑衍生的硒叶立德的合成及其在不对称环丙烷合成中的应用

以天然樟脑为手性源,在强碱作用下与甲基硒溴顺利反应得到exo型为主的硒醚产物,再经还原及与不饱和的烯丙基溴反应合成了新型结构的手性硒盐,该手性硒盐在强碱作用下能够形成硒叶立德,将其应用于手性环丙的不对称合成研究,实验结果表明具有很好的非对映选择性和对映选择性.