Unperturbed dimensions of atactic poly（dibenzyl itaconate）s

The unperturbed dimension and temperature character of poly(dibenzyl itaconate)s (PDBzI) are studied by a revised rotational isomeric state (RIS) method. The improved formulas of the mean-square radius of gyration, deduced by the pseudo-stereochemical equilibrium approach, may be used to investigate the configurational-conformational properties of atactic polymers with large side groups [poly(itaconates) for instance]. The calculated results showed that poly(itaconates) have larger dimension of the molecule than other vinyl polymers. Comparison of the dimension between considering and without considering side groups showed that the effect of large side groups on the unperturbed dimension for short-chain polymers is more obvious than that of long-chain polymers and, if the dimension of side groups increases, the effect also increases. The dimension differences of PDBzI between short-chain and long-chain polymers are investigated by the relation of characteristic ratios and temperature coefficients with temperature. Moreover, the dependence between the temperature coefficients and the tacticity of chains shows that the temperature characters of the isotactic, syndiotactic and atactic PDBzI chains have remarkable difference.     

谈教师育人工作"十六法"

传世千年的"孙子兵法",包括了许多丰富的论人、论智、论谋论策的哲学思想,教书育人工作从这些智慧结晶中不断吸取教益、借鉴和启迪,在实践中,运用"孙子兵法"中的某些谋略和手法,总结出教书育人工作"十六法".     

从野生植物三颗针中提取黄连素

对用水做溶剂从野生植物“三颗针”(又名黄牛刺 )中提取黄连素的小规模作坊式生产方法进行了探索。采取循环法提取 ,可提高黄连素产率和纯度。这为川西北山区人们利用当地野生植物资源提供了一条合理生产途径 ,具有较好的经济效益和社会效益。     

胰岛素史话（二）：胰岛素的生产和结晶化

一、胰岛素的生产作为多伦多奇迹的胰岛素的开发和生产不能不提到美国埃里制药公司,尤其是公司研究所长克鲁斯的远见卓识。克鲁斯所以能在胰岛素发现的第一时间就和班廷及麦克劳德接触。是因为他不但看到了这一发现的重大意义,而且只有大量生产使之实用化才能更有价值,这样不但能挽救众多糖尿病人的生命,同时也会给公司带来了巨大的经济效益。     

聚酯聚醚嵌断共聚酯的合成及性能研究

以对苯二甲酸为主要原料，合成了一系列配比的聚酯聚醚嵌断共聚酯（PTMG－PET），用示差扫描量热（DSC）方法和光学解偏振方法分别研究了该体系的热性能和等温结晶动力学。结果表明，共聚物组成和结晶温度均会影响材料的结晶行为，这将有利于控制和改善PET的加工性。     

在明辨中深度理解概念——“体积与容积”的教学思考与实践

教师应该围绕概念内涵的核心来组织和开展教学活动。以"体积与容积"一课的教学思考与实践为例,谈在具体教学中,如何通过深刻分析概念本质及其蕴含的数学思想,来设计有利于学生慎思、明辨的学习活动,促进学生深度学习,真正把知识内化为能力。     

聚合物结晶动力学

总结了几种常见的用于描述聚合物等温及非等温结晶行为的动力学方法,并结合具体的应用实例对这些动力学模型的优缺点等方面进行了简单的讨论。     

成核剂对聚烯烃的结晶和力学性能的影响

本文利用加入各种类型的成核剂的方法得到了不同结晶形态的聚乙烯(PE)和聚丙烯(PP);用偏光显微镜研究了各种成核剂的成核作用和结晶形态;用显微激光分析仪和差动热分析(DSC)研究了各成核剂对结晶和熔融过程的依赖关系,并测定了它们对结晶度的依赖关系,研究了它们对拉伸力学性能的影响。研究结果表明,成核剂可以明显地使晶粒细而均匀,能改变结晶和熔融速率,以适应各种工艺性要求,但对力学性能的影响较小,因此可以根据工艺和使用要求选用不同的成核剂。     

Investigation of oil-air two-phase mass flow rate measurement using Venturi and void fraction sensor

INTRODUCTION Accurate measurement of multiphase fluids flow rates in the petroleum industry is of great importance. The most reliable measurement technique for multi-phase flow is separating the mixture and using con-ventional devices for measuring single-phase flow. However, in many cases the separation is not practical from both technical and economical points of view. An alternative solution is the multiphase flow me-tering system, usually consisting of a combination of devices for ph…     

纳米二氧化钛光催化性能研究

Nano-TiO2 powders with pure anatase sturcture were prepared by the method of precipitation-solution-gelation,using H2TiO3,hydrogen peroxide and ammonia as reactants.Active red X-3B dye solution was selected as a model pollutant for the photocatalysis degradation experiments,The effects of grain sizes,dosage and microostructure of nano-TiO2 on itsphotocatalysis properties were studied.The results show that photo-activity of the nano-TiO2 is enhanced with the grain sizes reducing or dosages increasing of nano-TiO2,Howerver,excess increase in nano-TiO2 concentration is not advantageous to the enhancement of the photo-activity.Anatase TiO2 demonstrated a higher photo-activity than rutile TiO2,The dye solution hardly degraded without nano-TiO2 powders being added into it or under sunlight irradiation.