烯丙基保护基在多羟基化合物中的应用

烯丙基保护基由于能够在温和的反应条件下,在羟基、氨基等基团中引入和脱除,并且具有很好的区域选择性和化学选择性,因此被广泛应用于有机合成中。本文介绍了烯丙基保护基的发展历史,综述了烯丙保护基对多羟基化合物中不同羟基的选择性保护应用,并阐述了烯丙保护基的引入和脱除的机理及方法。     

氨基改性聚醚型聚硅氧烷的制备及其柔软性能研究

用含氢硅油、烯丙基缩水甘油醚、烯基聚醚的硅氢化加成产物-聚醚/环氧硅油与胺反应制得了氨基改性聚醚型聚硅氧烷（APEPS）,对其结构与性能进行了表征和研究。结果表明,含氢硅油分子量、有机胺结构、氨基改性聚醚型聚硅氧烷的硅含量对APEPS性能有影响。提高硅含量、增加氨值,可改善APEPS的柔软性与滑爽感,但对织物的吸湿性影响不大。     

官能团转化法制备羧基硅油及其柔软性能研究

用氨值为0．2895mmol/g、－／Mn=52650的氨丙基硅油（APS）与环状二元酸酐如琥珀酸酐（SA）、马来酸酐（MA）、邻苯二甲酸酐（PA）反应得了三种不同羟基烃基的硅油（CAS）,对其结构,性能进行了表征和测定。实验结果表明：三种CAS均能改善聚酯／粘胶纤维织物的柔软弹性,撕裂和断裂强度,但PA改性APS制备的CAS－3硅油,其分子侧链中的邻羧基苯甲酰基对硅油的柔软性能有影响;另外较高分子量的CAS能捉供织物更好的柔软性,而羧值变化对织物的吸湿性,回弹性影响较大,但对织物的柔性影响较小。     

固载蛋白A交联聚甲基丙烯酸缩水甘油酯连续床亲合色谱柱的制备及性能考察

采用沉淀聚法“原位”（in-situ)聚合合成了交联聚甲基丙烯酸缩水甘油酯连续床色谱柱,对其进行化学改性后,分别得到含有11个碳原子间隔臂以及不含间隔臂键合了蛋白A的高效亲合色谱柱。考察了这两种色谱介质的性能,结果表明含有间隔臂的介质有一定的疏水性;对传统制备蛋白配基的亲合色谱介质的合成路线进行了改进;采用不含间隔臂的亲合柱测定了人血浆中人免疫球蛋白G（HIgG)的含量,所测得的定量标准曲线线性相关系数达到0．999;考察了流速对合成的连续床色谱柱柱压的影响,当流速高达9．0mL/min时,柱压也仅为6．5MPa;采用pH梯度对HIgG的不同亚基进行了分离。     

Effects of nonionic surfactant and sodium dodecyl sulfate layers on electroacoustics of hexadecane/water emulsions

Hexadecane-in-water emulsion droplets were formed in a homogeniser in the presence of a mixture of an anionic surfactant (sodium dodecyl sulfate, SDS) and nonionic surfactants of various chain lengths [nonylphenol ethoxylate (C₉φE_N, N=100, 40 and 30) or an alcohol ethoxylate (Brij35)]. The dynamic mobility of the oil droplets was then measured using a flow-through version of an AcoustoSizer. Large changes were observed in the dynamic mobility of the particles formed with the mixed surfactants compared to particles formed with SDS alone. O'Brien's “gel layer” model was employed to interpret the data. The characteristics of the adsorbed layer appeared to be similar whether the nonionic surfactant was adsorbed concurrently with the SDS as the emulsion formed or was merely added afterwards to the emulsion established. The particle size, the charge and the molar fraction of SDS had virtually no effect. The layers formed with the nonionic surfactants decreased in thickness with decreasing molecular weight as expected. Passage through the homogeniser itself had no effect on the properties of the largest nonionic surfactant and, hence, on the adsorption layer formed with it. Received: 4 October 2000 Accepted: 16 October 2000     

纤维素氧膦-钯催化有机锡试剂和酰氯偶联反应的研究

报道了采用纤维氧膦－钯络合物为催化剂,有机锡试剂与取代肉桂酰氯进行交叉偶联合成查耳酮化合物。考察了催化剂的催化性能及影响反应的因素。XPS实验结果表明,催化剂中起催化作用的是金属态钯。     

时间分辨红外发射光谱研究C2H3+NO反应体系

The elementary reaction of C2H3＋ NO has been reported for the first time in this paper.C2H3 radical was produced by laser photolysis of vinyl bromide at 248 nm. Vibrationally excited reaction products H2CO,NCO and HCN were observed. Two exothermic reaction channels leading to HCN＋ H2CO and CH3＋ NCO are identified.     

CH2+O2反应的反应机理

CH2与 O2的反应是不饱和碳氢化合物燃烧过程中的一个十分重要的反应 .CH2（基态,三重态）与 O2反应的实验研究工作已有不少报导 [1－ 5],其主要产物有两 组 :H2O＋ CO和 CO2＋ H2,这些产物表明反应在反应体系的单重态位能面上发生 .至今还未见到关于 CH2＋ O2反应机理的完整的理论研究报导 .本文用 CASSCF方法详细研究了 CH2＋ O2反应的机理,给出从反应物至两组不同最终产物的完整的反应途经的描写 .1计算方法 　　计算使用量子化学高斯 98 W软件 .用从头算 CASSCF(8,8)/6-31G(d,p)方法在 CH2＋ O2单重态位能面上以优化…     

NOTES ON ERDOS' CONJECTURE

Let Xn,n 1,be a sequence of independent random variables satisfying P(Xn = O) = 1 － P(Xn = an) = 1 － 1/pn,where an,n 1,is a sequence of real numbers,andpn isthenthprime,setFN(x)=P(N∑Xnn=1 x).The authors investigate a conjecture of Erdos in probabilistic number theory and show that in order for the sequence FN to be weakly convergent,it is both sufficient and necessary that there exist three numbers x0 and x1 ＜ x2 such that limsup(FN(x2) －FN(x1)) ＞ 0 holds,and Lo =N→∞ lim FN(x0) exists.Moreover,the authors point ont that they can also obtain the same N→∞ result in the weakened case of liminfP(Xn = 0) ＞ 0.n→∞     

Tomographic analysis of the central magnetohydrodynamic oscillations on the HT-7 tokamak

Multi-channel soft x-ray (SX) detectors are applied to generate images of magnetohydrodynamic (MHD) oscillation on the HT-7 tokamak, and the data from SX cameras are analysed by using the Fourier--Bessel harmonic reconstruction method and the singular value decomposition. The image reconstruction of SX emissivity is obtained on the assumption of plasma rigid rotation. One of the important phenomena in the HT-7 discharge is the transition from the sawtooth oscillations to the MHD oscillations when the plasma density grows higher. The MHD structure observed in the SX tomography is featured as follows: the magnetic surface of MHD structure is made up of the crescent-shaped ``hot core' and the circular ``cold bubble'. The structure of the magnetic surface is relatively stable. It rotates in the direction of the electron diamagnetic drift at a frequency being the oscillation frequency of the MHD oscillations.