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911.
Benzo[b] thiophene derivatives. XVIII. The sulfur isosteres of harmaline,harmine and related isomers
T. R. Bosin R. P. Maickel A. Dinner A. Snell E. Campaigne 《Journal of heterocyclic chemistry》1972,9(6):1265-1266
The sulfur analogs of harmaline, 7-methoxy-3,4-dihydro-1-methyl[1]benzothieno[2,3-c]-pyridine (Ib), harmine, 7-methoxy-1-methyl[1]benzothieno[2,3- c ]pyridine (IIb), and corresponding 6-methoxy isomers (Ic and IIc) have been synthesized for pharmacological evaluation as monoamine oxidase inhibitors. 相似文献
912.
Gas-chromatographic determination of the product distribution in the synthesis of sodium borohydride
A gas-chromatographic method has been developed for determination of the sodium borohydride and methanol content of alkaline aqueous solutions of NaBH(4). From the ratio between NaBH(4) and CH(3)OH the product distribution in NaBH(4) synthesis from NaH and B(OCH(3))(3) in mineral oil can be calculated and the amount of the by-product NaBH(OCH(3))(3) formed can be estimated. A separation and extraction procedure for the mineral oil dispersion must precede the gas-chromatographic analysis. Sodium borohydride is determined by measurement of the 2-propanol formed after treatment of the solution with acetone, whereas methanol can be determined directly by gas chromatography, with 1-propanol as internal standard. The analysis of the synthesis products is thus the separation and detection of simple alcohols. 相似文献
913.
The known triterpene tetraoside holothurin A has been isolated from the Pacific Ocean holothurianHolothuria squamifera. By using two independent methods — enzymatic cleavage and two-stage Smith degradation — 22,25-epoxyholost-9(11)-ene-3β,12α,17α-triol, C30H46O6, which is the native aglycone of holothurin A, was obtained. The structure of the native aglycone has been established on the basis of the results of IR, mass, and PMR spectroscopy. 相似文献
914.
Golembeski T 《Talanta》1975,22(6):547-549
Atomic-absorption spectroscopy was used to determine trace amounts of selenium accurately in U.S. Geological Survey standard rocks, GSP-1, W-1 and BCR-1. The results obtained were compared with those obtained by neutron-activation analysis and excellent agreement was found; in addition, the selenium:sulphur ratio was calculated and agreed with results obtained by other workers. 相似文献
915.
V. G. Kharchenko S. N. Chalaya T. M. Konovalova 《Chemistry of Heterocyclic Compounds》1975,11(2):125-136
The literature data touching upon the synthesis of thiapyrylium salts and the stability of the thiapyrylium cation as compared with its isoelectronic analogs, as well as the nucleophilic, oxidation, anion-exchange, and other reactions of the salts with substituted and unsubstituted thiapyrylium cations are examined in this review. 相似文献
916.
A simple and sensitive method for determination of benzodiazepines in plasma has been developed using high-performance liquid chromatography in a reverse-phase mode. The method is illustrated by application to plasma samples containing diazepam and N-desmethyldiazepam at concentrations which would be encountered during therapy, with limits of detection of 10 ng/ml and 2 ng/ml for diazepam and N-desmethyldiazepam, respectively. 相似文献
917.
J. H. Augustson J. W. Haynes T. W. Sanders 《Journal of Radioanalytical and Nuclear Chemistry》1980,60(2):373-383
A method for the determination of uranium based on235U thermal neutron fission, has been developed and employed on samples of ashed fish tissue and seaweed. The method involves
a post-irradiation ion exchange separation of iodine isotopes. The 884 keV photopeak of134I is used for measurement. Uranium detection limits in the samples concerned have been estimated to be 1·10−8g in terms of natural uranium. The precision achieved in analysing several series of 3–5 samples was 4–10 per cent. The accuracy
of the method was tested by employing an independent neutron activation procedure based on239U measurement. The accuracy of both methods was checked by analysing NBS SRM 1571 ‘Orchard Leaves’. 相似文献
918.
S. D. Sokolov T. N. Egorova P. V. Petrovskii 《Chemistry of Heterocyclic Compounds》1974,10(5):516-520
The 4-nitro derivative is formed in the nitration of 3,5-diphenylisoxazole (I) in acetic anhydride. Mononitration of isoxazole I in concentrated H2SO4 gave 3-phenyl-5-(p-nitrophenyl)isoxazole, while polynitration gave a mixture of dinitro derivatives, among which 3- (m-nitro-phenyl)-5-(p-nitrophenyl)isoxazole was identified. The structures of the isolated products were established by means of the spectra, by reaction-chromatography methods, and gasliquid chromatography, as well as by a comparison with genuine samples of the two mononitro and four dinitro derivatives of isoxazole I. 相似文献
919.
The application of an inductively coupled high-frequency plasma source to the determination of iodine, mercury, arsenic and selenium by atomic emission spectrometry at wavelengths less than 200 nm is described. Optimal conditions have been established, and the spectral interference effects at different atomic lines for each element have been investigated. With the type of instrumentation employed, the determination of iodine at 183.04 nm, mercury at 184.96 nm, arsenic at 189.0 nm and selenium at 196.09 nm is recommended to minimize spectral interferences. No chemical or physical interferences resulting from the influence of foreign ions on the solute vaporization process have been noted. 相似文献
920.
Summary A study is made of the mechanism of hemolysis by anionic surface-active agents. It is supposed that the primary site of the hemolytic attack by anionic agents is the protein moiety of the red cell membrane at physiological pH. The role of phospholipid release in hemolysis increases as the PH of the medium decreases.
Zusammenfassung Der Mechanismus der Hämolyse durch anionische oberflächenaktive Agentien wurde untersucht. Es ist anzunehmen, daß primär der hämolytische Angriff durch anionische Agentien beim physiologischen PH am Proteinteil der Erythrozyt-Membran zu suchen ist. Mit der Abnahme des PH des Mediums spielt die Phospholipid-Freistellung bei der Hämolyse eine immer größere Rolle.相似文献