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991.
M. E. Umstead S. A. Lloyd J. W. Fleming M. C. Lin 《Applied physics. B, Lasers and optics》1985,38(4):219-224
The reaction of NO2 with isobutane, induced by 488 nm laser radiation, to form 2-nitro-2-methylpropane has been investigated and the results computer-modeled according to two possible reaction mechanisms. The first scheme involves the direct abstraction of H from isobutane by vibronically excited NO2 (NO
2
*
), and the second, abstraction by an intermediate NO3 radial produced by NO
2
*
+NO2. The modeling results strongly support the NO
2
*
scheme as the dominant reaction mechanism. 相似文献
992.
993.
1. Contrary to the observations of earlier workers, it has been shown that formic acid can be quantitatively oxidixed by ceric sulphate in the presence of concentrated sulphuric acid. 2. Tartaric, malonic, malic and glycolic acids can also be oxidized completely to carbon dioxide and water by the following general procedure : to a known amount of the organic acid is added ceric sulphate (excess) solution in dilute sulphuric acid and the mixed solution refluxed for ten to fifteen minutes. Concentrated sulphuric acid (double the volume of the reaction mixture) is then added taking care that formic acid is not lost during the addition, and the mixture again refluxed for 45 to 50 minutes. The excess ceric sulphate is determined by titrating against ferrous ammonium sulphate. 3. The complete oxidation of the above acids provides satisfactory methods for their quantitative estimation. 相似文献
994.
995.
Chen T Barton SC Binyamin G Gao Z Zhang Y Kim HH Heller A 《Journal of the American Chemical Society》2001,123(35):8630-8631
996.
The resolved structure of the lowest-energy oxo to osmium charge-transfer absorption band of trans-[OsO2(malonate)2]2- is analyzed on the basis of the exact molecular Ci symmetry determined from the structure of a crystal used for spectroscopy. The multiple progressions observed in the polarized spectra are rationalized in terms of the deviations from idealized D4h point group symmetry and compared to the spectra observed for complexes with D2h symmetry such as trans-[OsO2(oxalate)2]2- that show only a single dominant progression for this transition. 相似文献
997.
E. G. Le Roux M. Peisach C. A. Pineda M. A. B. Pougnet 《Journal of Radioanalytical and Nuclear Chemistry》1988,120(1):97-104
The split-root technique was used to study the effect of varying the growth media on the elemental content of nutrient elements in the roots of grape vines. The varieties 2-1 (R99 x Jacquez) and Sauvignon blanc (Vitis vinifera) were grown in Hoagland water culture with and without added aluminium. The elemental concentrations of Mg, Al, Si, P. S, Cl, K and Ca in the dried roots were determined by PIXE. Roots grown in Al-rich media were deficient in Mg and Ca, but enriched in Al. There was a correlation between Al and Si but the uptake differed in the two varieties. 相似文献
998.
B. Schuh C. Neureiter H. Jäger L. Windholz 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1996,37(2):149-153
Laserspectroscopic investigations were performed on a collimated atomic beam of barium (natural isotope abundance). The metastable ground levels (3D1,2,3 and 1D2) of the investigated lines were populated by a discharge burning in barium vapour directly in front of the oven hole. We could investigate 14 spectral lines between 580 and 690 nm. The tensor polarizabilities of the upper and the lower level as well as the differences in the scalar polarizabilities could be determined. Spectra in magnetic fields up to 0.03 Tesla showed no deviation from the pattern resulting from a simple Russell-Sounders coupling. 相似文献
999.
Condensations of 2,2,2-trifluorodiazoethane with pentanal, cyclohexancarboxaldehyde and benzaldehyde have been performed in presence of antimony pentachloride or boron trifiuoride. These reactions lead mainly to homologated aldehydes or ketones α substituted by a trifluoromethyl group. 相似文献
1000.
The addition of perfluoroalkyliodes CF3(CF2)nl (n= 3, 5, 7) to isocyanides 2 produces perfluoroalkylimidoyl iodides 3 under thermal conditions when the isocyanide nitrogen substituent is n-butyl or cyclohexyl, but fails when it is t-butyl or 2,6-dimethylphenyl. The same reaction can be induced at room temperature by the addition of decimolar quantity of copper powder. This type of metal-catalyzed condensation is general for all perfluoroalkyliodides and isocyanides studied. The perfluoroalkylimidoyl-iodides 3 have been transformed into a variety of perfluorocarboxylic acid derivatives (amides, amidines. imidates, imidoylfluorides) and perfluoroalkylamines. 相似文献