自由基聚合中扩散效应分析

自由基聚合扩散效应包括“笼蔽效应”、凝胶效应和玻璃化效应,本文以聚合物大分子扩散理论发展为线索,首先讨论了基于粘度理论、标度理论、链缠结理论、自由体积理论等从宏观尺度描述自由基聚合扩散效应的模型,然后深入到微观分子尺度,从初级自由基的扩散行为讨论了“笼蔽效应”,基于增长自由基的三种扩散行为解释了凝胶效应和玻璃化效应,最后简单介绍了其他理论模型,并对理论未来的发展进行了展望。     

药物化学中的大分子效应※

药物种类按照分子量来划分可以分为小分子药物(自然提取或化学合成的)和大分子药物(生物制剂). 尽管目前小分子药物仍然是市场的主流, 但其研发增速趋缓, 而大分子药物在药物研发中的地位日渐突显, 并被预期在未来药物市场中占据越来越高的份额. 除了生物制剂大分子药物, 将小分子药物与天然或合成大分子结合制备得到的化学合成大分子药物, 近年来受到药物研究者们越来越多的关注. 由于大分子具有丰富的骨架结构及空间构架, 其所特有的骨架效应、多价效应, 以及通过分子组装而产生的聚集效应和靶向效应等, 能够为药物化学的设计带来更多新的可能. 有鉴于此, 本综述将简略介绍药物化学设计中的大分子效应, 重点讨论合成大分子的骨架效应、多价效应、聚集效应和靶向效应等为药物化学设计所带来的新性能. 通过对药物化学中大分子效应所带来的优势、问题和重要研究进展的探讨, 以期能够推动化学合成大分子药物的发展, 为药物化学设计提供新的思路.     

纳米材料的特性及其应用

纳米材料作为材料科学中的重要一员 ,因其具有特殊的性质 ,已成为纳米科学技术的重要发展方向之一。本文介绍了纳米材料的特性、应用研究的进展及前景     

空化效应在有机废水处理中的应用研究

综述了空化效应的机理及其在有机废水处理中应用的研究进展.介绍了超声降解水中有机污染物的机理、影响超声降解的因素以及超声降解与其它处理方法的联用,评述了射流和涡流空化效应产生的机理及其在有机物处理中的应用,表明射流和涡流空化比超声空化效率更高,并且在处理量上具有明显优势,还对空化效应在有机废水处理中的应用前景作了展望.     

电子效应对单取代苯定位效应和反应活性的影响

单取代苯的定位效应和反应活性主要受取代基的电子效应控制,列表总结了取代基的电子效应与定位效应和反应活性的关系,分析了烃基电子效应的特殊性,取代基具有-Ⅰ效应的普遍性。除卤素取代基外,探讨了共轭效应的方向对定位效应和反应活性的决定作用。     

铊污染及其生态健康效应

对铊污染及其生态效应，包括铊的地球化学特性、环境分布状况、生理毒性和人体慢性铊中毒的症状作了简要综述，分析了铊污染的来源，提出了铊污染的防治对策。     

有机固体的非欧姆特性

根据电子结构观点,一般有机光导体等固体材料,可以看作是禁带宽度高达3-5eV(即光吸收限的能量)的半导体或绝缘体。因此根据热力学理论,由带间热激发所产生的载流子和由杂质能级中电子或空穴的热激发所产生的非平衡载流子,对有机固体的电导都不会有显著贡献,然而实际上对于处在高场(F≥10⁵V/cm)下的有机固体材料,可以测量到一定的电流,而此电流随外场增加呈超线性增加,即非欧姆电导性,有机固体的这种非欧姆特性对研究其电子过程是能够提供重要信息的,这就提出了有关非欧姆暗电导与光电导的物理意义的基本问题。     

Thorpe-Ingold效应及其在有机成环反应中的应用

本文首先介绍了Thorpe-Ingold效应及其相关理论和实验研究进展,然后综述了近年来Thorpe-Ingold效应在形成三、四、五和六元环产物的环化反应中的应用。Thorpe-Ingold效应可以有效地促进分子内和分子间环化,提高环化的产率和速率。该效应主要通过空间效应、电子效应或者两者协同起作用,在某些情况下,该效应还会受催化剂和溶剂等影响。利用该效应可以促使一些难以发生的环化反应顺利进行,并能获得较好的产率。     

离子特异性效应调控的功能水凝胶

离子特异性效应又称Hofmeister效应,是指不同离子对生物大分子或聚合物分子的溶解能力产生不同影响的现象,这对指导开发多功能聚合物材料具有重要意义。本文主要以离子与水之间、离子与大分子溶质之间的相互作用为出发点介绍了离子特异性效应的基本产生机制,介绍了离子特异性效应调控水凝胶力学、抗冻、刺激响应性等性能的研究进展,分析了离子对水凝胶性能进行调控的原理,总结了离子特异性效应在水凝胶实际应用中发挥的作用。本文将为功能水凝胶的设计和制备提供指导。     

包覆效应与压片法X射线荧光光谱分析

提出了在压片法X射线荧光光谱分析中存在包覆效应。用粉末压片X射线荧光光谱法测定刚玉镁砂浇注料的成分时,氧化镁的测定结果偏高,氧化铝的测定结果偏低,且偏低量、偏高量相近。用玛瑙研钵将样品不断研磨至更小的粒径时,上述现象没有明显的改变,表明此现象不属于粒度效应。用分别研磨至0.096mm的刚玉和镁砂粉末,按氧化铝和氧化镁含量与浇注料相近的比例混合均匀后,分别用压片法和熔片法测定,发现两种制片方法测定结果相近,表明上述现象也不是矿物效应。因此,提出了包覆效应的概念。用已有的报道证实了包覆效应,并指出了粒度效应、矿物效应和包覆效应的区别。     

“6S”在高校基础化学教学实验室细化管理中的灵活应用

主要介绍"6S管理"在厦门大学基础化学教学实验室内部细化管理过程中的应用实践与效果,特别是实验环境、物品定位管理、试剂管理、仪器管理等方面的具体做法,为高校化学教学实验室的建设和有效管理提供适应面广、操作性强的可借鉴经验。     

Convenient synthesis and NMR spectral studies of variously substituted <Emphasis Type="Italic">N</Emphasis>-methylpiperidin-4-one-<Emphasis Type="Italic">O</Emphasis>-benzyloximes

Abstract  A series of variously substituted N-methylpiperidin-4-one-O-benzyloximes were synthesized by three different methods. Among them, the direct conversion of 2,6-diarylpiperidin-4-ones into the corresponding oxime ethers (method A) was proved to be better than the other two methods in the sense of good yield, convenience, easy work-up and quick reaction time. All the synthesized compounds are characterized by IR, Mass and NMR (¹H NMR, ¹³C NMR, ¹H-¹H COSY, ¹H-¹³C COSY and HMBC) spectral studies. The conformational preference of the synthesized oxime ethers with/without alkyl and aryl substituents at C-3/C-5 and C-2/C-6 is discussed using the spectral data. The observed chemical shifts and coupling constants suggest that the synthesized oxime ethers adopt chair conformation with equatorial orientation of all the substituents, whereas 1-methyl-3-isopropyl-2,6-diphenylpiperidin-4-one-O-benzyloxime also exists in boat conformation. Based on the NMR data, the effects of oximination on ring carbons and their associated protons and alkyl substituents are discussed. In addition, the effect of NMe group on the 2,6-diarylpiperidin-4-one-O-benzyloximes was also studied. Graphical abstract        

基于现代信息技术的结构化学一维势箱理论和HMO法“翻转课堂”教学设计

In the article, we presented an instructional design of "Particle in One-Dimensional Box Theory" and "HMO Theory" application based on flipped classroom teaching. The students are instructed to use both "Particle in One-Dimensional Box Theory" and "HMO Theory" to solve the electronic structure of olefins and enhance their understanding of quantum mechanics theory via comparison of "Particle in One-Dimensional Box Theory" and "HMO Theory".     

Making "wheels" and "cubes" from triangles

[Mn(IV)Mn(II)3] triangular units directed by the presence of tripodal alcohols self-assemble in the presence of azide and acetate ligands to form either a [Mn24] "wheel" or a [Mn32] "cube".     

对“硫酸亚铁铵制备”实验的再认识——批判性思维教育的最好案例之一

介绍了"硫酸亚铁铵制备"实验中存在的问题,总结了30多年来人们针对该实验存在的问题进行改进所采取的措施,给出了对该实验再认识的一些探索和具体做法及效果。     

The effect of pressure on the ionization of water at various temperatures from molal-volume data1

The apparent molal volumes of dilute (0.002 to 1.0m) aqueous HCl and NaOH solutions have been determined at 0, 25, and 50°C and NaCl solutions at 50°C. The partial molal volumes ( ) of HCl, NaOH, and NaCl solutions have been determined from these apparent molal volumes and other reliable data from the literature. The partial-molal-volume changes ( ) for the ionization of water, H₂OH⁺+OH^–, have been determined from 0 to 50°C and 0 to 1m ionic strength from the partial molal volumes of HCl, NaOH, NaCl, and H₂O. The partial molal compressibilities ( for HCl, NaOH, NaCl, and H₂O have been estimated from data in the literature and used to determine the partial molal compressibility changes ( ) for the ionization of water from 0 to 50°C and 0 to 1m ionic strength. The effect of pressure on the ionization constant of water has been estimated from partial-molal-volume and compressibility changes using the relation from 0 to 50°C and 0 to 2000 bars. The results agree very well with the directly measured values.Contribution Number 1548 from the University of Miami.     

在化学类通识教育课程中开展“课堂辩论”对大学生能力培养的探索与实践

This paper explored "the classroom debates" in "nutrition chemistry" course. After evaluating the students' expectation in participating activities, the participating degree and their gains from the activity, it was found that the performance and gains from the "classroom debate" were influenced by provincial locations, genders and majors. The results showed that "the classroom debates" need to coordinate the students' speculative thinking ability, creative thinking, team playing, medical ethics and professional education as a whole. This would help the students to form a way of critical thinking as well as the right outlook on life and value system.     

Conformationally imprinted receptors: atropisomers with "write", "save", and "erase" recognition properties

[reaction: see text] An atropisomeric receptor with "write", "save", and "erase" recognition properties is presented. The receptor adopts a complementary conformation when heating in the presence of an ethyl adenine-9-acetate guest molecule. This complementary hydrogen bonding conformation is "saved" upon cooling to room temperature due to the reestablishment of restricted rotation and is stable even upon removal of the guest. Finally, the atropisomeric receptor can be "erased" by heating in the absence of the guest.     

"Clickable" polymersomes

Polymersomes, composed of amphiphilic polystyrene-block-poly(acrylic acid) (PS-b-PAA), with the periphery being covered with azide groups, were used for further functionalization using "click" chemistry.