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51.
对设备监理质量控制程序的探讨,有利于我国设备工程监理质量控制体系的完善并尽快与国际惯例接轨,使监理质量控制工作逐步走上专业化的道路。 相似文献
52.
SHEN Wen-Jie YAN Shi-Run ZHOU Jing-Lai ZHANG Bi-JiangInstitute of Coal Chemistry Academia Sinica Taiyuan Shanxi 《天然气化学杂志》1995,(3)
The kinetics of the Fischer-Tropsch Synthesis reaction is studied in an internally recycled reactor (CSTR) over a commercial, precipitated Fe/Mn/K catalyst. Kinetic data are obtained with 1 47-4.04 H2/CO feed gas over a temperature range of 265-320℃, a pressure range of 1.0-2.6 MPa, and a space velocity range of 300-800 h-1 . The kinetic model which fits the experimental data well is the same as that of the intrinsic kinetics, i.e. -RH2 CO=kPH2PCO/(PCO bPH2O, where k is the kinetic constant for the rate-determining step and b is a function of temperature only. This model may be derived by assuming that the rate-determining step is the hydrogenation of adsorbed CO according to the enol mechanism. It is found that the CO usage ratio is probably independent of synthesis gas conversion and total pressure, and the catalyst shows high water-gas-shift activity. 相似文献
53.
导数-同步荧光光谱法直接测定尿样中的洛美沙星 总被引:11,自引:0,他引:11
研究了洛美沙星在不同 pH值介质中的荧光特性 ,发现在 pH =3 3时 ,洛美沙星荧光波长有 4 0nm红移 ,据此建立了一种导数 同步荧光光谱法直接测定尿样中洛美沙星的新方法。经样品测定 ,其检测限为0 35mg·L- 1 ,平均回收率为 97%~ 10 4 % ,相对标准偏差为 0 83%~ 1 6 2 %。 相似文献
54.
55.
推行企业工伤保险制度是建立健全社会保障体系的一项重要内容。分析了国内外工伤保险制度及我国推行工伤保险制度中存在的问题,提出了扩大保险范围、实现工伤保险社会化、保险待遇给付、工伤保险法律化的建议。 相似文献
56.
喹诺酮药物是一类重要的化学合成抗菌素 ,其临床应用正在不断扩大[1] 。氧氟沙星 (OFLX)和环丙沙星 (CPLX)结构非常相似。本文采用胶束薄层色谱法分离了两种药物。加入 1%氨水的 0 0 0 15mol·L-1十六烷基三甲基溴化铵 (CTAB)和 1%十二烷基磺酸钠 (SDS)的等体积水溶液作为展开剂 ,聚酰胺薄膜作为固定相。考查了CTAB浓度 ,SDS浓度及氨水对氧氟沙星和环丙沙星Rf 值的影响。在选定条件下 ,Rf 值分别为 0 87和 0 76 ,在激发波长为 2 80nm处对其进行了荧光测定。测定了该方法的稳定性和灵敏度。本文首次使用胶束溶液分离了氧氟沙星和环丙沙星 相似文献
57.
Voltammetric Behavior of Semicarbazide at Graphene Modified Electrode and Application to Detection
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Herein voltammetric behaviors of semicarbazide (SEM) are investigated by employing a graphene modified working electrode, which displays attractive electroanalytical properties. In the acetate buffer solution of pH 4.00, there is a well‐defined oxidative peak of SEM, attributing to the irreversible and adsorption‐controlled electrode reaction with 2 electrons participation. The values of apparent heterogeneous electron transfer rate constant k′s with the redox are 0.0061 s?1 and 0.0009 s?1, respectively, for two scan rate section. After the experimental parameters, which influence the voltammetric responses of SEM, including supporting electrolyte, pH, accumulation time and accumulation potential, etc., are optimized, it is found that the anodic peak current of SEM is proportional to its concentration in the range of 4 ‐ 40 μmol/L with a detection limit of 1 μmol/L (S/N = 3). Then, an electrochemical method for detecting SEM quantitatively is developed successfully. The concentrations of SEM in fortified tap water samples are tested with satisfactory recovery, indicating that the novel method is strongly promising in the environmental monitoring application. 相似文献
58.
3,4‐Ethylenedioxythiophene Functionalizationed with Tetrathiafulvalene: Synthesis and Selective Esterification
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Lei Zhang Changzhi Wu Chengyun Wang Hujin Zuo Yongjia Shen 《Journal of heterocyclic chemistry》2014,51(5):1277-1281
3,4‐(Hydroxymethyl‐ethylenedioxy)thiophene ( 4 ) and 3,4‐(2′‐hydroxypropylenedioxy)thiophene ( 4' ′) were synthesized from dimethyl 3,4‐dihydroxythiophene‐2,5‐dicarboxylate ( 1 ), which were isomers and difficult to separate. When they were esterified with tetrathiafulvalene carried carboxylic acid group, only 3,4‐(hydroxymethyl‐ethylenedioxy)thiophene ( 4 ) could be esterified. No such selectivity was observed when the isomers were esterified by lauric acid and benzoic acid, respectively. 相似文献
59.
Electrochemical activities of typically electrochemical targets at three kinds of modified carbon electrodes, i.e. carbon ionic liquid electrode (CILE), graphene/carbon paste electrode (CPE), and ionic liquid-functionalized graphene (IL-graphene)/CPE, were compared in detail. The redox processes of the probes at IL-graphene/CPE were faster than those at CILE and graphene/CPE from cyclic voltammetry. An electrochemical method for the simultaneous determination of guanine and adenine was described with detection limits of 6.5 × 10−8 mol L−1 (guanine) and 3.2 × 10−8 mol L−1 (adenine). Single A → G mutation of sequence-specific DNA could be discriminated by the IL-graphene/CPE. 相似文献
60.
Hongyan Liu Ruixia Yan Riguang Zhang Baojun Wang Kechang Xie .Key Laboratory of Coal Science Technology of Ministry of Education Shanxi Province Taiyuan University of Technology Taiyuan Shanxi China .College of Chemistry Chemical Engineering Shanxi Datong University Datong 《天然气化学杂志》2011,20(6):611-617
A density-functional theory(DFT)method has been conducted to systematically investigate the adsorption of CHx(x=0~4)as well as the dissociation of CHx(x=1~4)on(111)facets of gold-alloyed Ni surface.The results have been compared with those obtained on pure Ni(111)surface.It shows that the adsorption energies of CHx(x=1~3)are lower,and the reaction barriers of CH4 dissociation are higher in the first and the fourth steps on gold-alloyed Ni(111)compared with those on pure Ni(111).In particular,the rate-determining step for CH4 dissociation is considered as the first step of dehydrogenation on gold-alloyed Ni(111),while it is the fourth step of dehydrogenation on pure Ni(111).Furthermore,the activation barrier in rate-determining step is higher by 0.41 eV on gold-alloyed Ni(111)than that on pure Ni(111).From above results,it can be concluded that carbon is not easy to form on gold-alloyed Ni(111)compared with that on pure Ni(111). 相似文献