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21.
为建立一种快速、简便、灵敏测定葡萄糖酸锌含量的方法,在非离子型表面活性剂聚氧乙烯异辛基苯基醚(TritonX-100)存在下,用2-(3,5-二溴-2-吡啶偶氮)-5-二甲氨基酚(3,5-diBr-DM-PAP)作显色剂,直接光度法测定了葡萄糖酸锌。结果表明,该法显色络合物最大吸收波长为560 nm,线性范围为0~1.5μg.mL-1,表观摩尔吸光系数为1.10×105L.mol-1.cm-1,回收率为98.7%~102.2%,具有操作快速、简便,结果灵敏可靠等优点,应用该法直接测定补锌口服液葡萄糖酸锌含量,结果满意。  相似文献   
22.
Polystyrene (PS) fibers with core-shell structure were prepared by coaxial electrostatic spinning using liquid epoxy or curing agent as the core and PS solution as the shell. Scratch self-healing coatings were realized by using the healant-loaded core-shell fibers in the matrix.  相似文献   
23.
Two New C—21 Steroidal Glycosides from Cynanchum aurichulatum   总被引:2,自引:0,他引:2  
Two new C-21 steroidal glycosides, cynanauriculoside I and cynanauriculoside Ⅱ, were isolated from the roots of Cynanchum aurichulatum. Their structures were established using spectroscopic methods including one and two-dimensional NMR.  相似文献   
24.
对用溶胶凝胶法制备的CdS/SiO2复合材料进行低频Raman散射研究,结果表明可从其低频Raman散射峰位计算出CdS微晶的粒径,两种不同的低频振动模式由激发光的两种偏振方向加以区分,低频Raman散射射的二级散射峰根据实验结果加以指认,所得平均粒径结果与透射电镜观察结果有较好的对应关系,复合材料吸收光谱吸收边蓝移与CdS纳米子粒径之间存在着密切的关系,实验证明,样品吸收边能量与CdS平均粒径的  相似文献   
25.
The efficient utilization of carbon dioxide (CO2) as a C1 feedstock is of great significance for green and sustainable development. Therefore, the efficient chemical conversion of CO2 into value-added products has recently attracted a lot of research attention in recent years. The transformation of CO2 generally requires high-energy substrates, specific catalysts, and harsh reaction conditions due to its high thermodynamic stability and kinetic inertness. Consequently, several efforts have been dedicated toward the development of high-performance catalysts and new reaction routes for CO2 conversion over the last few decades. To date, many routes of convert CO2 into value-added chemicals have been proposed, together with the development of heterogeneous and homogeneous catalysts. Among the advanced catalysts reported to date, ionic liquids (ILs) have been widely investigated and show great potential for the efficient, selective, and economical conversion of CO2 into highly valuable products under mild conditions, even under ambient conditions. Some task-specific ILs have been designed with unique functional groups (e.g., —OH, —SO3H, —NH2, —COOH, and —C≡N), which can act as the solvent, absorbent, activating agent, catalyst, or cocatalyst to realize the transformation of CO2 under metal-free and mild conditions. In addition, a variety of catalytic systems composed of ILs and metal catalysts have also been reported for the transformation of CO2, in which the combination of the IL and metal catalyst is responsible for CO2 conversion with high efficiency. In this review article, we summarize the recent advances in IL-mediated CO2 transformation into chemicals prepared via C—O, C—N, C—S, C—H, and C—C bond forming processes. ILs that can chemically capture CO2 with high capacity are first introduced, which can activate CO2 via the formation of IL-based carbonates or carbamates, thus realizing the transformation of CO2 under metal-free and mild conditions. Recent progress in IL-mediated CO2 transformations to form carbonates and various kinds of N- and S-containing compounds (e.g., oxazolidinones, ureas, benzimidazolones, formamides, methylamines, benzothiazoles, and other chemicals) as well as CO2 hydrogenation to give formic acid, methane, acetic acid, low-carbon alcohols, and hydrocarbons has been summarized in this review with a focus on the reaction routes, catalytic systems, and reaction mechanism. In these reactions, ILs can simultaneously activate the substrate via strong H-bonding in addition to activating CO2, and the cooperative effects among the ionic and molecular species and metal catalysts accomplish the reactions of CO2 with various kinds of substrates to afford a wide range of value-added chemicals. Finally, the shortcomings and perspectives of ILs are discussed. In short, IL-mediated CO2 transformations provide green and effective routes for the synthesis of high-value chemicals, which may have great potential for a wide range of applications.  相似文献   
26.
The purpose of this project was to prepare fluorescent dyes that could absorb energy at relatively short wavelengths, and fluoresce in the near-IR region. To achieve this, copper- and palladium-mediated C-N couplings were used to prepare the ‘cassettes’, i.e the carbazole derivative 3b and the carbazole-, phenothiazine-, and phenoazine-squaraines 4b-d. These compounds have carbazole, phenothiazine, and phenoazine donor-components that absorb around about 300-320 nm, and squaraine acceptor-parts that fluoresce in the range 650-700 nm. The efficiencies of energy transfer from the donor to the acceptor, and the overall quantum yields of the cassettes were determined.  相似文献   
27.
In recent years, the determination of Cr (VI) has attracted great attention because of its toxicity to human, plants and animals1-5. Usually, in the industrial waste water, the concentration of Cr (VI) is relatively high and should be determined frequently. So, an accurate, quick, and convenient method for the measurement of Cr (VI) in environmental water, as well as in river, lake, sea and tap water, is of great importance. The method for determination of Cr (VI) by diphenylcarbazine …  相似文献   
28.
合成了五个2,6-二乙酰吡啶缩肼基硫代甲酸酯双希夫碱合铜(Ⅱ)配合物,用元素分析、磁化率、红外光谱及紫外-可见光谱等对它们进行了表征,研究了配合物的电化学性质和Cu3L22X2(X=Cl-、SCN-)的光电子能谱。结果表明:五个Cu(Ⅱ)配合物均为三核配合物,在Cu3L22(SCN)2中存在Cu(Ⅱ)间的自旋-交换作用。  相似文献   
29.
反应性复合乳液的合成、表征及其交联反应   总被引:1,自引:0,他引:1  
利用种子半连续乳液聚合方法合成了核层或壳层带有环氧基以及壳层带有羧基的3种不同核/壳结构的乳胶粒子,通过物理共混带环氧基和羧基的乳胶粒子,得到了两种反应性复合乳液.利用透射电镜和激光动态光散射对乳胶粒子进行了表征,其粒径分布较窄,粒径分布的多分散系数为0.062,平均粒径约76 nm,乳胶粒子具有明显的核/壳结构.通过胶膜的凝胶率和膨胀率的测定和红外光谱分析对反应性复合乳液中乳胶粒子的扩散及交联反应进行了研究,并探讨了不同核壳结构复合乳液对涂膜机械性能的影响.研究表明,当反应性复合乳液中的环氧基和羧基分别分布在乳胶粒子的核层和壳层时,有利于聚合物分子链的充分扩散和化学交联反应的进行,从而提高涂膜的物理化学性能,当甲基丙烯酸缩水甘油酯(GMA)含量为10 wt%时,涂膜的拉伸强度达20.3 MPa.  相似文献   
30.
钴希夫碱配合物及其分子氧加合物的合成与表征   总被引:5,自引:0,他引:5  
以β-萘酚醛与一系列二胺缩合为配体,合成了钴的配合物。通过测定配合物在各种溶剂中吸收的氧气,得到了配合物与分子氧的摩尔比。并从各种溶剂中分离出了一系列2:1和1:1(Co/O_2)的分子氧加合物。对这些配合物和分子氧加合物进行了元素分析,红外、紫外一可见光谱和磁化率的表征,并研究了性质与结构的关系。  相似文献   
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