流动注射荧光法测定羟基自由基

研究Sn2 + 催化H2 O2 产生的·OH的反应 ,·OH与Ce3+ 作用后氧化生成无荧光的Ce4 + 。通过测定Ce3+ 的荧光强度的变化可间接测定所产生的羟自由基 ,并结合流动注射技术 ,确定了体系最佳实验条件。测定抗氧化剂清除羟自由基的实验 ,证明该体系可作为在线筛选抗氧化剂的方法之一。     

极谱过程温度效应的研究(Ⅲ)——催化反应速率常数和反应活化能的测定

催化反应在极谱分析中的应用及反应速率常数的测定已有报道。通常根据Koutecky公式计算催化反应速率常数,而反应活化能则由不同温度下测定的速率常数,按照Arrhenius公式计算。我们根据前文提出的可逆、不可逆、准可逆、动力和催化过程各种极谱电流——温度关系的普遍方程式,测定了Ti(Ⅳ)-H_2SO_4H_2C_2O_4-KClO_3、Mo(Ⅳ)-H_2SO_4-NaNO_3、Mo(Ⅵ)-H_2SO_4-NH_4NO_3体系催化反应速率常数和反应活化能(或表观活化能),结果令人满意。     

A new Dendrobine-Type Alkaloid from Dendrobium nobile

A new dendrobine-type alkaloid has been isolated from stems of Dendrobium nobile lindl.Its structure has been identified on the basis of spectroscopic method.     

The adsorption behavior of p-hydroxybenzoic acid on a silver-coated filter paper by surface enhanced Raman scattering

On dried filter paper coated with silver nanoparticles, surface-enhanced Raman scattering (SERS) spectra of p-hydroxybenzoic acid (PHBA) were studied, and high-quality SERS spectra were obtained, indicating that the silver-coated filter paper is a highly SERS-active substrate. The analysis showed that the adsorption behavior of PHBA molecules on silver nanoparticles coated on filter paper was different from that in silver aqueous colloids. On the filter paper, it was found that the SERS spectra of PHBA changed with the proportion of PHBA molecules and silver nanoparticles, indicating that the adsorption behavior of PHBA molecules changed with the proportion. The probable reasons are given.     

Enhancive Synthesis of ‐lβ, 11‐Diol‐4‐en‐eudesmol

An enhancive synthesis of ?1β, 11‐diol‐4‐en‐eudesmol, starting from 2‐chloroacrylonitrile, is described. The effect of temperature on the Diels‐Alder reaction of 2‐chloroacrylonitrile with 2‐methylfuran and the condition of cationic cyclization of diene were discussed in detail.     

环境样品中五氯苯酚分析方法的研究进展

本文概述了国内外环境样品中五氯苯酚(PCP)测定方法的研究状况,包括分光光度法、HPLC法、GC法和免疫分析法等。重点介绍了PCP的提取、衍生化过程,同时总结了各种方法的优缺点。引用文献19篇。     

手性钌(Ⅱ)配合物对DNA的立体选择性断裂

八面体钌(Ⅱ)多吡啶配合物与双螺旋DNA插入结合后具有较强的结合能力,并且含有一个具有氧化一还原活性的中心金属离子．它们对氧化剂相对比较稳定,但对光比较敏感,因此可利用光辐射使之产生单线态氧或羟基自由基等而使DNA裂解．此外,这些配合物具有左手∧-和右手△-两种构型,与同样具有手性的DNA作用时,存在着立体选择性结合．并且在对DNA的断裂反应中也存在一定的立体选择性,可作为不同构型DNA的结构探针．     

Identification of Different Cobalt Nucleation on Glassy Carbon

The nucleation mechanisms of cobalt from sulfate solutions were studied by utilizing the electrochemical technique, chronoamperometry. It was found that the recorded current-time transients introduced from 1.0mol/L CoSO4 solution were complexes with unusual shapes. All characteristic features were identified as separate process. The instantaneous or progressive nucleation with 2D or 3D growth exists during the cobalt deposition, depending on the applied potentials.     

固相微萃取GC-MS法测定苹果不同品种中主要芳香成分的研究

利用固相微萃取(solid phase nmicroelraction,SPME)和气质联用技术对目前果汁生产企业主要用于制汁的金帅、澳洲青苹、国光、新红星、富士及秦冠等品种的主要芳香成分进行定性和定量分析,比较不同品种之间芳香成分在种类和含量上的差异。在香气成分的定量分析中,以脱香果汁为基体加入混合标样,采用内标标准曲线法制作标准曲线,消除由SPME带来的系统误差,提高了实验结果的准确性和精确性。