排序方式: 共有11条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
P Workman C J Little T R Marten A D Dale R J Ruane I R Flockhart N M Bleehen 《Journal of chromatography. A》1978,145(3):507-512
5.
The effect of variation in temperature on the first-derivative electron spin resonance spectra of transition metal ions in aqueous solution is reported. For the aquo ions of Mn(II), Cr(III), Fe(III) and vanadyl, and for hexafluoroferrate(III), an increase in temperature results in a decrease in line width with a concomitant increase in signal amplitude. In contrast, [Cu(H2O)6]2+ and [Ti (H2O)4F2]+ show an increase in line width and a marked decrease in derivative amplitude as the temperature is raised. Consequently, the choice of the optimum temperature for each system results in greatly improved sensitivity and lower limits of detection. Recording spectra at more than one temperature is also useful for detecting a given metal ion in a multicomponent system that has overlapping resonance lines. 相似文献
6.
We investigate the values of t(n), the maximum number of edges in a graph with n vertices and not containing a four-cycle. Techniques for finding these are developed and the values of t(n) for all n up to 21 are obtained. All the corresponding extremal graphs are found. 相似文献
7.
Identificatini and determination of aromatic nitro compounds by electron spin resonance spectrometry
Aromatic nitro compounds are quantitatively converted to the corresponding anion-radical form by electron tranfer at the surface of thermally activated magnesium oxide. The radicals are stable in the absorbed state, and the reaction is useful for the identification and determination of the parent compound. The method is applied to detect and quantify various nitrobenzenes, nitrotoluenes and teryl by electron spin resonance spectrometry. For 2,4,6-trinitrotoluene (TNT), the detection limit was ca. 10 ng; the r.s.d. at the 2 μg level was ± 1.8%. The analysis of hand-swab extracts that contained TNT at the trace levels demonstrateds a potentially important application of the method. 相似文献
8.
We describe what is to our knowledge the first use of fiber Bragg gratings written into three separate cores of a multicore fiber for two-axis curvature measurement. The gratings act as independent, but isothermal, fiber strain gauges for which local curvature determines the difference in strain between cores, permitting temperature-independent bend measurement. 相似文献
9.
10.
The use of electron spin resonance spectrometry with a modern instrument is described for the determination of polynuclear aromatic hydrocarbons (PAHs) down to nanogram levels, after adsorption on calcined silica/alumina. A single PAH or the total number of moles of PAHs can be determined. Implication for liquid chromatography are discussed. 相似文献