分光光度法测定豆类中铁的含量(Ⅱ)

豆类无污染,无农药残毒,营养丰富,具有特殊风味,并且很多豆类还有医疗保健作用.用分光光度法直接测定了豆类中铁的含量,方法简便快速准确,对指导人们合理食用豆类补铁及进一步开发豆类提供了可靠的理论依据.     

分光光度法测定野菜中铁的含量(Ⅲ)

野菜无污染、无农药残毒,营养丰富,具有特殊风味,并且很多野菜还有医疗保健作用.用分光光度法直接测定了野菜中铁的含量,方法简便快速准确,对指导人们合理食用野菜进行补铁及进一步开发野菜提供了可靠的理论依据.     

红外光谱法测定涕灭畏

农药涕灭畏系一种高效低残毒的农药。对它的定量分析过去都是采用化学法进行,比较费力、费时,为提高工作效率,保证生产过程中产品的质量,本文讨论了红外光谱法定量测定涕灭畏的方法,分析中选用1315cm~(-1)分析峰,此峰无其它干扰。     

碱溶-原子吸收光谱法直接测定贻贝、牡蛎和黄鱼中的微量元素

用NaOH溶液溶解贻贝、牡蛎和黄鱼，原子吸收法测定其中的Cu、Pb、Cd、Zn、Cr等元素。所测元素含量与标准推荐值基本一致，测定结果的精密度和准确度明显优于传统的酸溶法，满足海洋环境监测中生物体残毒的分析要求。     

一种新的农药残毒快速检测装置

本文报道了一种新的农药残毒快速检测装置。该装置基于酶催化动力学原理,以酶抑制率反映蔬菜中残留农药的总毒性。该装置集化学分析、光机电、信息、生物等技术于一体,可对六种样品进行同时检测。测量准确度高,精密度好,方便快速,适合于各种实际应用场合,具有广泛的应用前景。     

火焰光度法测定天然气中总硫

火焰光度法对磷化物和硫化物具有较高灵敏度和选择性,自1962年Draegerwek报导用于测定空气中磷化物和硫化物以来,获得了很大的发展。近几年来已被广泛地用于含磷、硫农药残毒以及空气和水中磷、硫污染物的分析。但是用该法直接测定天然气或有机液体中的微量总硫时,由于大量甲烷和有机物的干扰,     

用手持式农药速测仪酶法现场测定蔬菜中有机磷及氨基甲酸酯农药残毒

检测蔬菜中有机磷类及氨基甲酸酯类农药残留通常采用气相色谱、色谱-质谱联用[1]等方法, 不适应现场快速检测的要求. 关于快速分析方法, 国外主要采用电化学酶传感器法[2], 还有微孔板酶标仪法[3]. 前者存在电极易受污染且需再生处理的麻烦; 后者难以实现现场检测. 国内报道的有酶抑制光度法[4]、单点目视比色法及速测卡法等, 其中目视比色法和速测卡法虽然具有操作简便等优点, 但由于实验误差较大, 灵敏度较低, 只能作为定性分析. 本文在前期工作的基础上[5,6], 研制了一种体积小(140 mm×70 mm×30 mm)、重量轻(整机180 g)、能耗低(电池可连续使用50 h)且现场实用的手持式农药残毒速测仪, 开发了专用试剂包并建立了蔬菜中有机磷类及氨基甲酸酯类农药残毒的现场分析方法, 对6种蔬菜及速冻玉米样品进行了实际检测, 并与GC-MS方法[1]进行了对照, 结果令人满意.     

3-烯丙氧基-1,1-二氧代苯并异噻唑的克莱森重排反应

3-烯丙氧基-1,1-二氯代苯并异噻唑(国际通用名为Probenazole,商品名为Oryzemate)是防治水稻稻瘟病和白枯病的内吸性的新型杀菌剂,也是一种低毒、无残毒的安全农药。从这一化合物的结构特征来看是属于[3.3-σ热重排]体系,故很可能在热条件下不甚     

酶抑制法可快速检测农药残留

<正>农产品中农药残留检测、监测,蔬菜上农药残毒的快速检测是人们保护自己、净化市场所采取的必要手段。在许多国家,由于蔬菜生产基地相对集中,蔬菜批发商把蔬菜运到销售地点后,即将蔬菜储存在仓库中,同时向地方政府所属的残留检测部门申请农药残留检测。这样,检测部门就有相对充足的时间对抽检的样本用气相色谱仪或其他分析仪器     

低比表面多孔硅珠DG-6做为气液色谱键合固定相基料

近年来,化学键合固定相在色谱分析中已应用日广。在气液色谱方面则以白色载体为基料用聚乙二醇或聚酯制备的键合相,使用较多。例如,在农药残毒污染分析中或作为固定相或作为改性载体,在国内亦见报导。我们曾对三种国产载体,用聚乙二醇-二万按Aue氏方法热键合的效果做过对比试验。结果证明低比表面多孔硅珠的键合效果较好。     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

解决能源问题的新途径——光解水制氢的研究

面对日益枯竭的能源危机,氢能是一种洁净、最有前景的替代能源。目前在各种制氢的方法中光催化分解水制氢的研究最多,光解水过程中催化剂最关键,本文对利用太阳能光解水的途径、提高光催化反应效率以及光催化剂的开发研究进行了综述。     

化学单元教学设计的探索

论述了单元教学是落实化学新课程三维目标的基本教学过程,同时对教学单元的含义、教学单元的选择与建构、化学单元教学设计及其意义进行了阐述。     

Synthesis of phenolic components of Grains of Paradise

Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared.     

Summary of development of the theory of stability of colloids and thin films

In this review, the research of the author in the field of colloidal systems is summarized. The factors influencing colloidal stability are systematized and analyzed. Examples are presented to illustrate the practical utilization of the theory of stability of colloids and thin films.This review was prepared on the basis of the works of the author, which were awarded the State Premium for 1991 in the field of science and technology, chemistry section.Institute of Physical Chemistry, Russian Academy of Sciences, 117915 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1708–1717, August, 1992.     

NiY分子筛表面酸性影响其选择性吸附脱硫性能的机理研究

采用原位红外光谱技术,以噻吩、环己烯和苯为模型探针分子,分别考察单一烃分子在NiY分子筛上的吸附与反应行为以及噻吩与烯烃、芳烃间的竞争吸附和催化反应行为。单一探针分子吸附研究发现,NiY分子筛中与Ni物种相关的Lewis(L)酸位是噻吩的选择性吸附活性位;噻吩和环己烯在NiY分子筛中Brnsted(B)酸位上发生的质子化和低聚反应明显弱于HY分子筛。双探针分子竞争吸附研究发现,环己烯二聚体在NiY中强B酸位上的强化学吸附与噻吩存在显著的竞争吸附行为。另外,苯和噻吩在NiY上的竞争吸附现象在373K时明显减弱。由此,在选择性吸附脱硫过程中,减少吸附剂表面B酸中心可降低烯烃对噻吩的竞争吸附,另外适当提高吸附体系的温度可以有效避免芳烃对噻吩的竞争吸附。     

黄酮化合物的合成研究进展

黄酮化合物是一类具有多种生物活性的天然产物,其经典的合成方法主要为查耳酮路线和β-丙二酮路线.近年来出现了许多新技术、新方法.本文介绍了2'-羟基查尔酮的氧化关环法、黄烷酮氧化法、改进的Baker-Venkataraman法及其他合成黄酮化合物的方法.     

On the possibilities of theoretical analysis of kinetics of the thermal decomposition of solids

The main reasons for changes in the environment surrounding us are discussed on the basis of thermodynamics of irreversible processes. Subsequently, relations between thermodynamics of irreversible processes and chemical kinetics are shown, then the possibilities of theoretical determination of rate constants on the framework of the modified RRKM theory are presented. These latter considerations are supplemented by a discussion concerning the possibilities of determining the activation barriers and structural changes (necessary to account for entropy changes upon reaction) in molecules kept on the surface of crystalline phases by combination of quantum chemistry methods for isolated molecules with those reflecting the influence of the environment (i.e. interaction within the lattice). Finally, the future of theoretical methods in examining the reactivity of solid state systems is briefly discussed.     

Kinetics of Electrophilic Fluorination of Steroids and Epimerisation of Fluorosteroids

Fluorinated steroids, which are synthesised by electrophilic fluorination, form a significant proportion of marketed pharmaceuticals. To gain quantitative information on fluorination at the 6-position of steroids, kinetics studies were conducted on enol ester derivatives of progesterone, testosterone, cholestenone and hydrocortisone with a series of electrophilic N−F reagents. The stereoselectivities of fluorination reactions of progesterone enol acetate and the kinetic effects of additives, including methanol and water, were investigated. The kinetics of epimerisation of 6β-fluoroprogesterone to the more pharmacologically active 6α-fluoroprogesterone isomer in HCl/acetic acid solutions are detailed.