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1.
Margot Zimmermann 《Fresenius' Journal of Analytical Chemistry》1965,213(5):390
Ohne ZusammenfassungFrühere Mitt., vgl. diese Z. 201, 64 (1964); 202, 384 (1964); 204, 449 (1964); 207, 149 (1965). 相似文献
2.
Analytical and Bioanalytical Chemistry - 相似文献
3.
Analytical and Bioanalytical Chemistry - 相似文献
4.
5.
Analytical and Bioanalytical Chemistry - 相似文献
6.
R. Hönigschmid-Grossich und Margot Zimmermann 《Fresenius' Journal of Analytical Chemistry》1963,192(2):329-330
Ohne Zusammenfassung 相似文献
7.
The proton NMR in single crystals of ferrocene has been studied by multiple pulse techniques at room temperature. In crystals of natural shape with plane faces the angular dependence of the resonance frequency due to the anisotropy of the shielding and due to the bulk susceptibility was found to be of about equal size, making analysis of the data practically impossible. By using a single crystal sphere the shape dependent part of the susceptibility contribution could be eliminated. In addition, the resolution obtained by the multiple pulse technique is considerably higher for spheres than for non-spherical crystals. As the ferrocene molecules rotate rapidly about their fivefold axes at room temperature, the shielding tensor σ must be axially symmetric. Having this in mind, the data could be analyzed to yield both the shielding tensor with Δσ = σ6 - σ⊥ = ?6.5 ± 0.1 ppm, σiso = ?4.2 ± 0.5 ppm from a spherical sample of TMS and the anisotropy of the susceptibility Δ x = 30 × 10?6 cgs units. 相似文献
8.
Treating lophine with potassium at ?50° in an inert solvent yields the radical dianion 6 of this compound. The solution being warmed to room temperature, the radical rearranges to a red diamagnetic intermediate 7. In presence of potassium then the radical dianion 3 of 2-phenyl-4,5,(9′,10′)-phenanthrimidazole is formed which has been described earlier.ESR-spectroscopical investigations show, that the spin density in the 2-phenyl ring of radical 6 vanishes. According to spin density calculations 2-phenyl residue and heterocycle are strongly distorted. 相似文献
9.
13C and 31P chemical shift data for eight 2-methoxy-1,3,2-dioxaphosphorinanes are reported. Examination of pairs of geometrical isomers, which differ only in the orientation of the OMe substituent on PIII, have shown that both the 31P and the 13C signals of C4,6 atoms appear 3–4 ppm at higher field when the OMe is axial compared with the equatorial isomer. This observation can be associated with the 1–3 syn diaxial interaction between the phosphorus axial substituent and the axial hydrogens on C4,6 and should thus constitute, in the future, a supplementary tool for the structural analysis of this kind of compound. Important long range δ effects were observed both on 13C and especially on 31P chemical shifts. It is suggested that the high field δe effects could reflect a direct stereoelectronic interaction between the P atom and the cyclic C-5 atom. This interpretation is supported by a study of the 31P…13C coupling constants and their stereochemical dependence. 相似文献
10.
Summary Micromolar analyses of the nitrogen species NH3, NO
2
–
, and NO
3
–
in soil and other samples are usually accomplished by extracting several samples and testing each for a different species. This procedure is not viable when the quantity of the initial sample is limited. An improved method of separating and analysing for ammonia NH3(aq), nitrite NO
2
–
(aq), and nitrate NO
3
–
(aq) from a single small sample with concentrations of 0–50 mol/l is reported. No interferences or carryovers among the three nitrogen containing species were found. Uncertainties were ±2–5 mol/l and accuracies with respect to standards were ±3 mol/l. 相似文献