建构学习仪式感 提升学习主动性*——以元素化学学习为例

结合元素化学课程特色和当代大学生心理性格特征,提出以学生为主体、提升学生素养能力为重点,构建元素代言人、身边的化学(现象、实验)、翻转课堂等一系列课内外学习活动,以学习活动的仪式感促进学生进行自我暗示,塑造愉悦学习的情境,克服焦虑厌学的情绪,提升学生学习的主动性,并以学科育人的思想贯穿课程始终,营造有形有实、充满活力的元素化学课堂。     

Observation of Regime III Crystallization in Polyethylene/Montmorillonite Nanocomposites

Summary: Exfoliated and intercalated polyethylene/montmorillonite (PE/MMT) nanocomposites with high MMT content were prepared by in situ polymerization. The isothermal crystallization kinetics of the nanocomposites were analyzed with Lauritzen–Hoffman regime theory. Regime III crystallization, which is difficult to observe in linear polyethylene, appears in the PE/MMT nanocomposites. The broader temperature range of regime III crystallization in PE/MMT nanocomposites shows that the mobility and reptation ability of the PE chains are greatly reduced by the MMT, especially in the intercalated nanocomposite.

Plots of ln K/n + U*/R(T_c − T₀) against 1/T_c(ΔT)f for the intercalated and exfoliated PE/MMT nanocomposites.     

Effect of Free Trimethylaluminum Content in Methylaluminoxane on Performances of Bis(salicylaldiminate)nickel(II)‐Based Catalysts for Ethylene Polymerization

Summary: The performances of ethylene polymerization catalysts based on III and commercial methylaluminoxane were investigated by reducing the content of free trimethylaluminum in methylaluminoxane by its reaction with 2,6‐di‐tert‐butylphenol. This allowed optimization of the formulation of the catalyst, affording a high‐molecular‐weight linear polyethylene (PE) with a productivity [(1 900 kg of PE/(mol of Ni × h)], ten‐fold higher than that previously achieved for the same system adopting commercial methylaluminoxane not pre‐treated with the above phenol derivative.

     

Gamma irradiation of high density poly(ethylene)/ethylene‐vinyl acetate/clay nanocomposites: possible mechanism of the influence of clay on irradiated nanocomposites

A further study on mechanical properties and morphology evolution of high density poly (ethylene)/ethylene‐vinyl acetate/and organically‐modified montmorillonite (HDPE/EVA/OMT) nanocomposites exposed to gamma‐rays (0–200 kGy) has been achieved. The results showed that nanocomposites have superior irradiation‐resistant properties to HDPE/EVA blend in mechanical properties. A transmission electron microscope study verified that a face‐face ordered nanostructure had been induced by gamma‐rays. The aim of this paper is to provide a possible mechanism on how the OMT influences the general properties of irradiated nanocomposites, based on the results of thermal, flammability and mechanical behavior. Three facts are postulated to be responsible for the mechanism. The first is the segregation of nano‐dispersed clay layers not only reduces polymer oxidation but prevents crosslinking reactions. The second is the nanostructure evolution induced by gamma‐rays, which may impart nanocomposites improved elasticity. The last is due to the Hofmann degradation, whose degraded products have opposite roles, accelerating polymer oxidation or promoting crosslinking reactions. These facts interact as well as compete with others. The properties of the nanocomposites strongly depended on the prevalent effects developing with increasing irradiation doses. Copyright © 2005 John Wiley & Sons, Ltd.     

卵磷脂中PE及不同种类PC的高效液相色谱分析

卵磷脂具有重要的生理功能,是人体正常新陈代谢和健康生存不可少的物质,能改善治疗神经系统疾病,增强记忆力,防止心血管疾病等。在临床上卵磷脂的主要的用途是用于治疗动脉粥样硬化、脂肪肝、神经衰弱、营养不良及静脉注射脂肪乳的乳化剂、胆固醇结石的防治药物,引。美国、欧洲、日本等已将磷脂在临床上用于防治脑、心、肝、肿瘤等疾病。     

四硼酸根阴离子对氯型水滑石前体插层组装的动力学研究

根据四硼酸根对氯型水滑石(LDH—Cl)前体插层组装时溶液浓度的变化和不同反应进程产物的EDS,IR,XRD,TEM和TG—DTA表征研究了四硼酸根插层组装的动力学．结果表明,氯离子的交换溶出符合Stumm模型,四硼酸根的插入受控于扩散过程模型,插层产物保留了前驱体的层状结构及微孔结构,但插入大体积复杂离子B4O5(OH)4^2-引起晶胞c轴向体积和粒子尺寸的变化较大,晶胞参数c由2．399nm增大到2．558nm,通道高度h由0．3228nm增大到0．3756nm,粒子面向直径Da由15．16nm减小到8．92nm,径向尺寸Dc由10．93nm减小到4．55nrn;比表面积由92．63m^2／g增大到111．20m^2／g,LDH热分解特征亦有较大变化．     

红外光谱法在淀粉/聚乙烯低温热氧降解研究中的应用

共聚物;聚乙烯/淀粉共聚物;红外光谱法在淀粉/聚乙烯低温热氧降解研究中的应用     

以在线开放课程为核心进行一流课程的建设与实践

The development and integration of information technology with higher education facilitate the construction of the first-class online course, which has been a key objective for undergraduate education reform. Based on the student-centered idea, it is a valuable exploration and practice to integrate the online course with traditional teaching, and make efforts on innovative digitized teaching mode by taking the advantage of information technology.     

大学有机化学选论课程的教学改革探索

有机化学选论课程是有机化学专业必修课的深入与延伸,既要满足学生对日新月异的现代有机化学知识的需求,又要兼顾知识的系统性,需要在教学实践中不断探索。本文以创新教学素材、使教学与现代科研以及社会工艺相结合为出发点,探讨如何以学生为主体,培养学生的科学素养,提高学生自主学习能力的教学改革探索。     

从IB化学谈IBDP课程与国外大学的衔接

国际文凭大学预科课程（IBDP课程）是在全球被认可的具有较高学业水平的大学预科项目,以IBDP化学课程为切入点,从课程目标、课程大纲与要求、课程评估方式,结合大学对IBDP课程的认可来进行全面分析,探讨IBDP课程的设置与国外大学的衔接。