排序方式: 共有55条查询结果,搜索用时 187 毫秒
51.
Fluid–fluid and fluid–solid phase equilibrium were experimentally determined under pressure on the system methane + heptadecane using a full visibility cell. Measurements were performed using the synthetic method on mixtures ranging from pure heptadecane to 99% of methane. The liquid–solid phase transitions were investigated up to 90 MPa and fluid phase boundary was studied in the temperature domain from 293 to 373 K. The appearance of a minimum in the three phase (V–L–S) equilibrium curve is discussed and it is shown that the difference in the solid phase structure and the presence of a solid–solid phase transition do not affect significantly the phase diagram determined. 相似文献
52.
石蜡相光度法测定混合稀土中的铈 总被引:3,自引:0,他引:3
系统研究了Ce(Ⅳ)-8-羟基喹啉体系在石蜡相中的显色反应。在NH4Cl-NH3(pH=9.5)介质中,Ce(Ⅳ)-8-羟基喹啉有色络合物可定量被石蜡萃取,且固相色阶明显,铈量在0~100ug/50mL范围内符合比耳定律,从而建立了测量铈的新的固相分光光度法。其它稀土离子的干扰可通过双波长光度法测量扣除。方法应用于混合稀土合成样中铈的测定,结果满意。 相似文献
53.
54.
Wax sculptures contain several materials from both organic and inorganic nature. These works of art are particularly fragile. Determining their chemical composition is thus of prime importance for their preservation. The identification of the recipes of waxy pastes used through time also provides valuable information in the field of art history.The aim of the present research was to develop a convenient analytical strategy, as non-invasive as possible, that allows to identify the wide range of materials involved in wax sculptures.A multi-step analytical methodology, based on the use of complementary techniques, either non- or micro-destructive, was elaborated. X-ray fluorescence and micro-Raman spectroscopy were used in a non-invasive way to identify inorganic pigments, opacifiers and extenders. The combination of structural and separative techniques, namely infrared spectroscopy, direct inlet electron ionisation mass spectrometry and high temperature gas chromatography, was shown to be appropriate for unravelling the precise composition of the organic substances. A micro-chemical test was also performed for the detection of starch.From this study it has been possible to elucidate the composition of the waxy pastes used by three different sculptors at the end of the 19th century. Complex and elaborated recipes, in which a large range of natural substances were combined, were highlighted. 相似文献
55.
Denise Lowinsohn Patrick Gan Kristina Tschulik John S. Foord Richard G. Compton 《Electroanalysis》2013,25(11):2435-2444
The electrochemical behaviour of carbon paste electrodes prepared using nanocarbon and mineral oil was investigated and the results contrasted with different carbon and carbon pastes electrodes. The composition of carbon paste was studied by performing cyclic voltammetry performed in 0.1 M KCl solution in the presence of 4.0 mM Ru(NH3)6Cl3, a well‐characterized redox system commonly used to test the electrode behaviour. After optimisation of the paste composition, the sensors chosen were tested for the analysis and characterization of three different systems: Ru(NH3)63+/2+, FcCH2OH/FcCH2OH+ and acetaminophen. The ability to obtain high quality voltammetry from the nanocarbon electrode was demonstrated and simulation of the voltammetry allowed the extraction of electrode kinetic parameters with high precision. 相似文献