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51.
52.
茶汤及河水中铬的形态分析 总被引:11,自引:0,他引:11
本文采用717型强碱性阴离子交换树脂、活性炭分离富集与偶氮胂Ⅲ光度法结合,研究了铬形态的分离及测定,提出了铬的形态分析方法,有此法测定了茶汤及河水中铬的总量,悬浮态.溶解态、无机态、有机态、Cr(Ⅲ)和Cr(Ⅵ)。茶汤中铬主要以有机态存在,而河水中铬则主要以悬浮态存在。 相似文献
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Hongqiang Qu Caihong Liu Weihong Wu Lingzhi Chen Jianzhong Xu 《Journal of Thermal Analysis and Calorimetry》2014,115(2):1081-1087
Flame-retarded poly(vinyl chloride) (PVC) materials have been prepared by using zinc ferrite (ZnFe2O4 (ZFO)) combined with magnesium hydroxide (Mg(OH)2 (MH)). The effects of these additives on the combustion and thermal degradation of PVC samples were studied using the limiting oxygen index test, the smoke density rating test, thermogravimetric–differential thermogravimetry, and the cone calorimeter test. The results showed that ZFO and MH were good synergists for improving the flame retardancy and smoke-suppressing of PVC/MH/ZFO blends. ZFO can significantly improve the maximum mass loss velocity in the first stage, and reduce the initial decomposition temperature and the decomposition range in the PVC/MH/ZFO blends. The char yield at 700 °C of flame-retarded PVC clearly decreased below theoretical values due to the cationic cracking reactions in the presence of ZFO. Furthermore, the PVC/10MH/10ZFO showed strong flame-retarding synergism since the decreased average heat release rate value. And the PVC/19MH/1ZFO presented a significant smoke-suppressing effect by the least average specific extinction area, peak smoke production rate, and total smoke produce. Moreover, the CO and CO2 production was increased because of a large amount of fragment of char residue in contact air in the presence of ZFO. 相似文献
55.
研究固态化学反应对合成化学、理论研究以及工业生产都有重要意义,南京大学忻新泉等人在室温或低温温度条件下固相配位反应的合成及机理研究方面做了许多有意义的工作[1,2],为使低温温度固相合成法最终走向应用作了积极贡献。由于固相配位反应的热效应难以直接测定,热化学... 相似文献
56.
A new sensing method (BAW-TAL technique), which combined the bulk acoustic wave (BAW) technique with the gelation reaction of Tachypleus amebocyte lysate (TAL), was used for viscosity and density measurement and applied to the detection of Escherichia coliform (E. coli). This method depended on the fact that the viscosity and density of the mixture increased, and as a result, the resonance frequency decreased correspondingly after TAL was mixed with the heated E. coli solution that contained endotoxin. Results showed that the frequency shift was linearly related to the logarithm of E. coli concentration in the range of 2.7x10(4)-2.7x10(8) cells/ml. The correlation coefficient was 0.996. This BAW-TAL method was compared with the standard pour plate counts (PPC) method. The proposed method was much more rapid and simpler for detection of E. coli than the traditional methods. 相似文献
57.
In this paper, cyclic voltammetry, linear sweep voltammetry and chronocoulometry in connection with the hang mercury drop electrode were used to study NiTMpyP and its mixture with DNA. The reduction of NiTMpyP in our experimental conditions involves in 4e reduction of TMpyP. NiTMpyP interacting with DNA forms electrochemically non-active complex DNA-2NiTMpyP, which can not be reduced on the Hg electrode. The peak potential of NiTMpyP does not shift and its electrochemical kinetic parameters indicate no significant change in the presence of DNA. However, the reduction current of NiTMpyP decreases obviously due to the formation of DNA-2NiTMpyP, which implies its equilibrium concentration decreases when DNA was mixed. The decrease of peak current is proportional to DNA concentration, which can be applied to estimate DNA concentration. 相似文献
58.
An ion chromatographic method is described for the purpose of quality control in the process of monochloroacetic acid production. Using 2.5 mM NaOH–10% methanol as eluent, the simultaneous determination of acetic acid, monochloroacetic acid, dichloroacetic acid, and Cl− was obtained in a single run. Monochloroacetic acid and dichloroacetic acid showed good linearity in the range 0.1–20 and 0.15–20 μg/ml and correlation coefficients were 0.9999 and 0.9998, respectively. The detection limits (signal-to-noise ratio 3:1) of monochloroacetic acid and dichloroacetic acid were 17 and 25 ng/ml. This simple, sensitive, and time-saving method can be applied for composition analysis in acetic acid chlorination production. 相似文献
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[2,2]对环番([2,2]Paracyclophane)及其衍生物,具有特殊的分子结构和化学物理性能,在理论和实际应用方面受到很大的重视[1,2]。 相似文献