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91.
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Three new diterpenoids with a substituted α-cyclogeraniol skeleton have been isolated from the umbelliferae Magydaris panacifolia (Vahl) Lange, for which the names of magydar-2,13-dien-11,17-diol, 1, magydar-2,10 (20), 13-trien-17-ol, 2, and magydar-2,10(20), 13-trien-17-yl acetate, 3, are proposed. The structures of these substances have been deduced from spectroscopic and chemical data.  相似文献   
94.
A new class of cyclic telluronium salts has been prepared. All the salts are stable in solution in CHCl3 or dimethylsulphoxide (DMSO). Conductivity measurements in DMSO and dimethylformamide (DMF) have shown that considerable ion pairing occurs in solution. Infrared, 1H, 13C, 125Te NMR, and mass spectra are reported and discussed.  相似文献   
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Abstract— The thiophenyl ester of indole-3-acetic acid and indole-3-acetonitrile produce chemiluminescence in aerated dimethylsulfoxide in the presence of potassium t -butoxide. The emitter is the aromatic aldehyde. In the case of acetonitrile, the other product expected from the cleavage of an intermediate dioxetane, cyanate/isocyanate, has also been identified. Other auxins also chemiluminesce under similar conditions, but the emitters have not been properly identified.
These systems are models for the peroxidase catalyzed oxidation of indole-3-acetic acid to indole-3-carboxaldehyde and as such support the earlier inference (Vidigal et al , 1975) that the excited aldehyde is generated in the enzymic process.
An additional result is the observation of an exciplex between excited indole-3-carboxaldehyde and the thiophenylester of indole-3-acetic acid. This appears to be the first case of chemical generation of an exciplex by a route other than radical ion reaction, presumably by the dioxetane route.  相似文献   
97.
The epithermal neutron spectrum shape parameter in nuclear reactors is explained from a theoretical point of view in terms of the neutron slowing down density function. The latter is approximated by Fermi's age theory. Values for are calculated for a simple approximation of a nuclear reactor: a disk shaped fission neutron source in an infinite graphite moderator. The model produces -values with the correct sign and magnitude, compared to experimental values from the literature, determined in a real reactor. It is shown that varies strongly with distance to the neutron source and less strongly with neutron energy. The inappropriateness of average -values, obtained from the slope of quasi-straight lines produced by log-log plots of E versus E, for the correction of non-ideal epithermal neutron activation is discussed. Conclusions are formulated concerning the impact of an energy dependent on comparator type NAA.  相似文献   
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99.
Summary The application of GLC, HPLC and TLC to the analysis of pharmaceutical creams is discussed with special attention to sample clean-up. The results of the determination of hydrocortisone acetate, salicylic acid, benzoic acid, diethyl stilbestrol, chloramphenicol, diphenhydramine HCl, tretinoin and some cream base components by reversed phase HPLC are given.Presented at the 14th International Symposium on Chromatography London, September, 1982  相似文献   
100.
Treatment of methyl 3,5-dideoxy-β-D-erythro-pentofuranoside 8 with the Ph3P-CCl4 reagent gave none of the expected 2-chloro derivative but a mixture of l→2 linked oligosaccharides, 9, 10 with some higher homologues, terminated by αa 2-chloro-2,3,5-trideoxy-α-D-threo-pentofuranosyl unit at the non reducing end.  相似文献   
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