Copper catalyzed atom transfer radical copolymerization of glycidyl methacrylate and 2‐ethylhexyl acrylate

This investigation reports the atom transfer radical copolymerization (ATRcP) of glycidyl methacrylate (GMA) and 2‐ethylhexyl acrylate (EHA). Poly(glycidyl methacrylate) (PGMA) has easily transformable pendant oxirane group and poly(2‐ethylhexyl acrylate) (PEHA) has very low T_g. They are the important components of coating and adhesive materials. Copolymerization of GMA and EHA was carried out in bulk and in toluene at 70 °C at different molar feed ratios using CuCl as catalyst in combination with 2,2′‐bypyridine (bpy) as well as N,N,N′,N″,N″‐pentamethyl diethylenetriamine (PMDETA) as ligand. The molecular weight (M_n) and the polydispersity index (PDI) of the polymers were determined by GPC analysis. The molar composition of the copolymers was determined by ¹H NMR analysis. The reactivity ratios of GMA (r₁) and EHA (r₂) were determined using Finemann‐Ross and Kelen‐Tudos linearization methods and those had been compared with the literature values for conventional free radical copolymerization. The thermal properties of the copolymers were studied by DSC and TGA analysis. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6526–6533, 2009     

地方高师音专小提琴教学中存在的问题及其对策

地方高师要完成音乐教育的培养目标,教师应狠抓基础,让学生在技巧与音乐上协调发展,全面提高,在演奏、理论研究及教学实践方面均具备一定的能力;同时适当增加专业课课时,给专业课以应有的地位;营造学术氛围,创建音乐环境,让学生在接受音乐熏陶的同时,提高音乐素养,最终实现由音乐爱好者向合格的音乐教师目标的顺利转化。     

不孤独的孤独者--试论莫里亚克主人公角度表述的多层次双重性

莫里亚克笔下的黛莱丝是个性格复杂而又带模糊性的人物形象，本文试从主人公角度出发，探析其向内与向外、显性与隐性、平视与俯视三层次同时进行表述来完成人物性格表现的方法。     

变电所由于分频谐振引起误动作的技术分析

变电站投运时,因经常发生分频谐振现象而误发母线接地信号,或因谐振引起TV过压过励磁,严重时可能烧毁TV。本文通过对实际谐波进行理论分析,总结出防止分频谐振的几项措施,可供实际工程应用。     

Surface instability of orthotropic laminated materials under compression

The piecewise-homogeneous material model and the three-dimensional linearized theory of stability with the assumption of small subcritical strains are used to study the surface buckling of orthotropic and transtropic laminates. A plane problem is formulated, and characteristic equations are derived. A solution is found for a specific transtropic material with different orientations of the isotropy axis __________ Translated from Prikladnaya Mekhanika, Vol. 42, No. 7, pp. 64–72, July 2006.     

不同所有制企业高层管理者的差异研究

企业内部环境因素对企业的影响一直受到各方面的关注。本文是基于大样本的统计分析,着重对高层管理者这一企业内部环境因素在不同所有制企业配对组中的横向差异进行对比和分析研究。结果发现:在威望与素质方面,国有企业与三资企业和私营企业分别存在非常显著的差异;在高层对中层的信任与支持方面,三资企业与私营企业存在显著差异。最后,针对相应企业在高层管理者自身状况方面提出调整措施。     

单位分数和表1解的树结构

对单位分数和表1问题，将k=3，k=4，k=5的解结果加以分析并提出了分蘖、亚分蘖、拔节以及树结构的概念。     

Invariance of stationary probabilities of states for network of multiserver queues

A queueing network consisting of multiserver nodes with different sources of customers is considered. We investigate stationary probability distributions of network states. Their invariance with respect to the functional form of distributions of input and service processes is established under fixed expectations of these distributions and service discipline when any entering customer has a preemptive resume discipline.     

H粒子的能量

本文在H粒子是一个六夸克集团的假定下,考虑了s夸克与u、d夸克的质量差,用夸克势模型计算了H粒子最低态的能量,结果表明它是一个能量比(?)阀能高几百MeV的共振态。     

基于不同租期下的预防性维修优化策略

针对租赁市场的实际情况,提出了一种既考虑租期不同又考虑维修服务质量的多设备租赁的预防性维修策略;策略综合考虑了惩防成本、预防维修、小修、故障率阈值以及维修服务质量等因素对利润的影响,以出租方利润最大化为目标的预防性维修策略,优化了故障率阈值,并利用遗传算法共同优化了修复程度和不同租期下的维修次数;实例证明了模型的可行性,也为企业的设备维修管理提供了一种新的建模与决策思路。