有机/无机杂化纳米结构单元的空间构型研究

利用乙烯基三甲氧基硅烷(VMS)水解缩合, 制备了有机/无机杂化纳米结构单元乙烯基倍半硅氧烷(VSSO). 采用FTIR, NMR(¹H, ¹³C和²⁹Si)和MALDI-TOF MS测试, 结合SSO的结构通式T_n(OH)_x(OR′)_y [x, y = 0, 1, 2 …; n = 1, 2 …; T = RSiO_{1.5−(x + y)/2n}]推测出具有固定分子量的水解缩合产物VSSO所对应的多个结构简式. 运用量子力学计算的方法, 以单一VSSO整体分子为模型, 得出了各种结构的几何参数(Si-O和Si-C键长, Si-O-Si和O-Si-O的键角)和分子体系的总能量. 根据计算结果可知, VSSO的梯型结构较笼型结构具有较高的稳定性, 并得出VSSO可能的最合理、最稳定的结构类型是梯型的结论.     

离聚体共混体系在溶液中分子间缔合的粘度研究

研究了磺化聚苯乙烯离聚体／聚（苯乙烯－４－乙烯吡啶）共混体系，磺化聚苯醚离聚体／聚（苯乙烯－４－乙烯吡啶）共混体系的磺化聚苯醚离聚体／胺化聚苯醚共混体系在氯仿／甲醇混合溶剂中的粘度行为，结果表明，和它们分别对应的不含离子基的共混物相比，这三个共混体系都表现出较高的比较粘度，这是由于体系中的酸基及其盐和含氮碱基的引入，在共混组分间产生了强烈的离子相互作用，从而导致分子间的缔合，使比浓粘度提高，并讨论     

COMPATIBILITY IN POLYMER BLENDS OF POLY (VINYL ACETATE) AND POLY (METHYL METHACRYLATE)STUDIED BY NMR

Compatibility of poly (vinyl acetate) (PVAc) with poly (methyl methacrylate) (PMMA) mixtures has been studied by using nuclear magnetic relaxation, differential scanning calorimeter and small-angle X-ray scattering techniques. The nuclear magnetic relaxation time T_1's were measured as a function of composition in blends of PMMA and PVAc prepared from chloroform solution. The results show that the system is miscible for casting from chloroform solution.     

n-C3H7I和i-C3H7I的激光裂解

Studies on the photofragmentation of n-C_3H_7I and i-C_3H_7I have been carried out by a photofragment spectrometer with rotatable pulsed molecular beam crossed with KrF excimer laser beam. TOF spectra of the iodine atom fragments (Fig.1, 2) which show the separation of the primary photodissociation channels n-C_3H_7I→n-C_3H_7+I~*(~2P_(1/2)) n-C_3H_7+I(~2p_(3/2)) i-C_3H_7I→i-C_3H_7+I~*(~2P_(1/2)) i-C_3H_7+I(~2P_(3/2)) are obtatned at 12 different angles. The distribution of total translational energy E_(CM) of recoiling photofragments are then determined. The ratios I~*/I of the photodissociation channels of n-C_3H_7I and i-C_3H_7I are measured to be 1.61 and 0.96 respectively (Table 1). The ratios I~*/I obtained by photofragment translational energy measurement in this Lab~[3]. are good in agreement with most of results abtained by IR emission~[5] and LIF~[4] measurement except the data of i-C_3H_7I, which is much different from I~*/I=0.35 reported by Bershon~[4] using LIF method.The extent of internal alkyl fragment excitation E_(int)~R is also determined (Table 2) by energy balance. The fraction of the available energy (E_(av1)=E_(CM)+E_(int)~R) which goes into internal exciatation of the alkyl fragment increases from 12.5% for I~* channe of CH_3I to 64% for both channels of i-C_3H_7I. The results are consistent with direct impulsive dynamic model of unimolecular decomposition based on “soft” alkyl radicals.The facts that the ratio I~*/I decreases with increasing carbon atoms and that the difference of the internal excitation of alkyl radicals between the I~* (~2P_(1/2)) and I (~2P_(3/2)) channelsincreases with increasing carbon atoms should be related and important for better understanding the origin of the I(~2P_(3/2)) channel caused by the potential energy surface crossing~[3]. The results of the internal excitation of the alkyl radicals in the photodissociation are also valuable for prediction of secondary products during the UV photolysis of those alkyl iodides in the gas cell.     

核心素养视域下“说理”课堂的教学实践

“说理”课堂是核心素养视域下小学数学新的课堂教学理念之一.“说理”课堂旨在通过有效的数学交流,加深学生对数学知识的理解,促进学生深度思考,改变当前小学数学课堂普遍存在学生会“算”不会“说”的现象,落实学生数学学科素养的培养.本文从学生会“算”不会“说”的成因、“说理”课堂的内涵与实践意义、“说理”课堂的教学实施策略三个方面阐述了“说理”课堂的教学实践.     

平台—群柱基础对浪流冲击的动力反应分析

本文研究平台-群柱基础系统对浪流冲击的动力反应分析.文中考虑了群柱基础与水流和地基土的动力相互作用,由解析法给出了系统对浪流力激励的动力响应分析,给出了算例的位移响应结果,并讨论了系统参数对动力特性的影响.     

顺序注射化学发光联用技术测定食品中的碘

基于酸性溶液中HCHO存在下,KMnO4可氧化I-产生很强的化学发光的原理,建立了一个简单快速测定微量碘的顺序注射化学发光分析方法。I-在3.0×10-8~8.0×10-6mol/L范围内与发光强度呈良好线性关系。对2.0×10-6mol/L I-11次重复测定的相对标准偏差(RSD)为2.6%,方法的检出限(3σ)1.3×10-8mol/L,测定了4种食品中的碘量,回收率为92.8%~107.7%。分析频率为70 h。     

化学改性环氧树脂水基涂料的研究-涂膜性能

化学改性环氧树脂水基涂料的研究-涂膜性能     

环氧树脂水基化化学改性的研究

用对氨基苯甲酸改性环氧树脂 ,使其成为具有亲水性的树脂。测定了改性树脂的溶解性 ,发现改性后树脂在有机溶剂中的溶解性能变差 ,但在碱性溶剂中溶解性增强。对改性树脂进行了红外光谱表征 ,并根据环氧基特征峰的吸收对环氧基转化率进行了定量分析。测定了改性产物的DSC曲线 ,发现随着反应物中对氨基苯甲酸比例的提高 ,改性产物的玻璃化转变温度升高。涂膜的性能测试表明 ,对氨基苯甲酸改性环氧树脂水基涂料的机械力学性能和耐化学试剂性能比溶剂型纯环氧树脂要优越。     

矿物药的研究及发展概况

通过查阅、分析近十年来的文献,从矿物药的物理性质、结构、化学成分和药理学等方面,概述了矿物药的研究现状及存在的问题,并对矿物药的结构与药效之间的联系、微量元素的作用、元素的赋存状态与药效的关系及矿物药治病作用与中毒作用的量化界定等研究热点及发展动向作了简要的述评。