睾酮类兴奋剂测定中一些β-葡萄糖醛酸甙酶酶解能力的比较

睾酮是国际奥委会规定禁用的99种兴奋剂之一,由于睾酮是内源性激素,因此不能靠定性来判断运动员是否服用了睾酮,在人体激素代谢中,产生睾酮差向异构体——表睾酮,在男性黄种人中睾酮与表睾酮浓度比约为1:1,白种人中略高一些,根据这一情况,国际奥委会规定,人尿中睾酮与表睾酮之间浓度比不得超过6:1,尿中排泄出的睾酮和表睾酮是以葡     

甲硫醛单分子热分解反应

采用不对称Ｅｃｋａｒｔ势模拟了甲硫醛单分子反应体系，计算了各反应条件下反应速率常数及活化能，所得结果与甲醛结果作了比较。     

高效离子排斥色谱法测定饮料中的糖精钠

提出了一种用高效离子排斥色谱法测定饮料中糖精钠的新方法。以ＩｏｎＰａｃ ＩＣＥ－ＡＳ ６柱为分离柱，０．１０ ｍｍｏｌ／ＬＨ２ＳＯ４＋甲醇（９＋１）为淋洗液，２０２ｎｍ波长下紫外检测。在１－１００ｍｇ／Ｌ范围内，糖精钠的含量与峰面积呈 良好线性关系。检出限为０．６０ｎｇ，灵敏度优于以往采用离子交换色谱－电导检测法的结果。在实验条件下，饮料 中常见有机酸以及其它人工合成甜味剂等均不产生干扰。方法用于饮料中糖精钠的测定，加标回收率为９８％～ １０５％。此外还比较了电导检测、紫外检测和经化学抑制系统后紫外检测等三种检测方式对测定灵敏度的影响。     

Ni^2—交换蒙脱石中的镍物种及焙烧温度影响研究

对一组自制Ｎｉ＾２＋交换蒙脱石样品中镍物种的存在在形及焙烧温度影响进行了ＴＰＲ和ＸＲＤ考察结果表明，样品中镍负载量等于或小于Ｎｉ＾２＋的交换量时，镍主要以难还原听可交换性阳离子Ｎｉ（ＯＨ）＾ｑ＋ｘ和易还原的自由态镍Ｎｉ（ＯＨ）２或ＮｉＯ两种形式存在。     

从自然科学基金资助项目看我国环境化学进展和趋势

本文通过对近年来国家自然科学基金中环境化学学科资助项目的介绍和评述, 分析了我国环境化学基础性研究的进展, 对环境化学学科发展趋势作出了展望, 并对部分相关前沿领域的研究提出了建议。     

Determination of cerium in rare earth ores by fluorescence quenching of rhodamine 6G

A fluorescence quenching method has been developed to determine cerium with rhodamine 6G. The method is based on the oxidation of rhodamine 6G by cerium(IV) in sulfuric acid solution. The linear calibration range is 4.0 × 10^–7 -1.6 × 10^–6mol/L. The detection limit is 1.0 × 10^–7 mol/L. The relative standard deviation was 1.0% (n = 5). The method has been used to determine cerium in rare earth ores, with satisfactory results. The method offers the advantages of simplisity, sensitivity and selectivity.     

密度泛函理论研究碳链长度对氯化三烷基铵萃取氯化汞的影响

运用密度泛函理论方法研究了烷基碳链长度对氯化三烷基铵络合氯化汞的影响,计算结果表明,氯化三烷基铵与氯化汞的络合作用随着氯化三烷基铵中烷基碳链的增长而增强.通过对络合物的键长、Mayer键级和Mulliken电荷分析可知,电子富集在氯化三烷基铵的Cl原子上,并和Hg原子之间形成静电吸引作用.当烷基长度小于3时,烷基的电子效应影响较为明显,增强了原子之间的电子转移,使得络合物更稳定;当氯化三烷基铵烷基碳链长度大于3后,烷基链长对络合物中的电子转移不再有影响,络合物的稳定性受到烷基的几何效应影响更为明显.     

Separation of water-in-oil emulsion with microfiber glass coalescing bed

Water-in-oil emulsion separation through a fibrous media bed is a complex and challenging process in industries. In this article, we used a vertical column separator to investigate the effects of the height and porosity of the fiber bed, the structure arrangement (the mixed or the layered fibrous bed), the superficial velocity of the water-in-oil emulsion through the bed, and the influent water content of the emulsion on water removal. Four kinds of glass microfibers (GF1-GF4) with mean diameters of 0.6, 2.6, 4.6, and 8.0?µm, respectively, acted as the coalescence medium and composed the fibrous bed with different structure types. The separation efficiency could reach 97.1% with a relatively low pressure drop under the optimal bed structure and operational conditions. It also showed that the mixed bed had higher separation performance compared to the layered fibrous bed.