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961.
G. N. Dorofeenko E. I. Sadekova V. M. Goncharova 《Chemistry of Heterocyclic Compounds》1970,6(10):1218-1222
The properties of 1,3-dimethyl-6,7-dialkoxy-2-benzopyrylium salts were studied. The heterocyclic oxygen atom is readily replaced by nitrogen by reaction of the 2-benzopyrylium salts with primary amines, hydrazine, phenylhydrazine, glycine ethyl ester, and hydroxylamine; reaction with secondary amines leads to naphthalene derivatives. The activities of the methyl groups in the 1 and 3 positions of the heterocyclic ring are compared.For Communication IX, see [6].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1308–1312, October, 1970. 相似文献
962.
S. N. Karyagin V. F. Kiselev G. S. Plotnikov Yu. D. Fomin 《Theoretical and Experimental Chemistry》1990,25(5):504-509
Electrophysical methods and ESR measurements have been used to investigate the changes, photosensitized by molecules of rhodamine B (RB), in the charge states of electron traps created by molecules of p-benzoquinone (pBQ) in the Ge/GeO2 system. The results obtained in studying the quenching of fluorescence of RB molecules indicate that the photodestruction of electron traps is due to transfer of electronic excitation energy traps is due to transfer of electronic oxidation energy from the RB molecules to charged complexes formed upon adsorption of the pBQ. In order to select optimal conditions for recharging of such complexes, a study has been made of the relationship between the relative change in ESR signal and the concentration of adsorbed RB molecules.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 5, pp. 545–550, September–October, 1989. 相似文献
963.
N. A. Sosnina Z. Golbenko A. A. Akhunov Ya. S. Ziyaev Sh. I. Salikhov 《Chemistry of Natural Compounds》1989,25(5):596-599
A bradykinin-potentiating peptide has been isolated from the venom of the spiderLatrodectus tredecimguttatus. Its physicochemical properties and amino acid composition have been investigated in detail. It has been shown by biological testing on isolated neck of the rat uterus that the peptide increases the contractile effect of bradykinin in in vitro experiments. The “potentiating unit” is 2 · 10?3 mg/ml. A 50% increase in the hypotensive effect of bradykinin at a concentration of the bradykinin-potentiating peptide of 15 µg/kg of body weight has been found, the increase in the intensity of the effect being accompanied by a prolongation of its action. 相似文献
964.
R. M. Masagutov S. I. Spivak Z. Sh. Akhmadishin G. N. Kirichenko N. G. Grigorieva G. A. Tolstikov 《Reaction Kinetics and Catalysis Letters》1985,28(2):411-417
Kinetics of p-cumylphenol alkylation by isobutylene in the presence of 0.1–2 wt.% p-toluenesulfonic acid has been studied and a reaction scheme is suggested. The rate constants have been determined.
- 0,1–2 % . -. .相似文献
965.
The application of NMR and MS methods for detection of adulteration of wine,fruit juices,and olive oil. A review 总被引:2,自引:0,他引:2
Ogrinc N Kosir IJ Spangenberg JE Kidric J 《Analytical and bioanalytical chemistry》2003,376(4):424-430
This review covers two important techniques, high resolution nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS), used to characterize food products and detect possible adulteration of wine, fruit juices, and olive oil, all important products of the Mediterranean Basin. Emphasis is placed on the complementary use of SNIF-NMR (site-specific natural isotopic fractionation nuclear magnetic resonance) and IRMS (isotope-ratio mass spectrometry) in association with chemometric methods for detecting the adulteration. 相似文献
966.
A. N. Vasil’ev A. N. Lyshchikov O. E. Nasakin Ya. S. Kayukov V. A. Tafeenko 《Russian Journal of Organic Chemistry》2005,41(2):279-282
Reduction of alkyl-2-amino-5,6-dialkyl-3-cyanopyridine-4-carboxylates with sodium borohydride in protic solvents gave rise to 4-amino-3-imino-6,7-dialkyl-1,3-dihydrofuro[3,4-c]pyridines that at hydrolysis in acid medium afforded the corresponding lactones.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 2, 2005, pp. 288–291.Original Russian Text Copyright © 2005 by Vasil’ev, Lyshchikov, Nasakin, Kayukov, Tafeenko. 相似文献
967.
One of the main approaches employed to reach fast chromatographic separation is based on using columns containing up to 1000 capillaries with the diameter size down to 10-100 microm. The efficiency of such columns depends on the dispersion of the capillary radius and on the way of the liquid-film loading. We present general equations describing these effects. Specifically, we show theoretically and experimentally that the separation efficiency can be improved by using the loading methods specially designed in order to take into account correlation between the film thickness and capillary radius. 相似文献
968.
N. V. Myagkova G. R. Rakhmonberdiev Z. G. Sagdieva A. S. Sidikov 《Chemistry of Natural Compounds》1997,33(1):76-79
The thermodynamics of the mixing of water-soluble mixed cellulose esters with water has been studied. A dependence of the affinity of a water-soluble cellulose acetate for water on the nature of a new radical introduced into the macromolecule and the competing interaction of molecules of the same and different types has been shown. Thermodynamic analysis has demonstrated the dominating role of solvation among the various factors determining the interaction of cellulose acetomaleate and acetophthalate with a solvent. A fall in affinity in the cellulose aminoacetate-water system is due to the contribution of entropy effects, leading to an increase in the Flory-Huggins parameter.Tashkent Institute of Chemical Technology. Translated from Khimiya Prirodnykh Soedinenii, Vol. 33, No. 1, pp. 97–101, January–February, 1997. 相似文献
969.
P. Selucký N. V. Sistková J. Rais 《Journal of Radioanalytical and Nuclear Chemistry》1997,224(1-2):89-94
A new reagent for the highly selective extraction of cesium (e-1,7–2,2)4,8–8,4-(bis--o-phenylene)bisdicarbollidocobalt(1–)ate, [(C2B9H9)2(C6H4)2Co]–, abbreviated as BISPHECOSAN is described in this paper. The choice of organic solvent and solubilizer, dependence of distribution ratio of Cs+ on acidity and other parameters are studied. The extraction mechanism based on selective binding of Cs+ cation between two phenylene rings is presented and factors influencing the chemical stability of the reagent are determined. 相似文献
970.
Shapkin N. P. Razov V. I. Svistunova I. V. Skobun A. S. Starostina S. V. Tonkikh I. V. 《Russian Journal of Coordination Chemistry》2003,29(8):549-553
The effects of the nature of the metal atom and -substituents in aluminum(III), chromium(III), cobalt(III), and iron(III) acetylacetonates on the lifetime and intensity of a long-lived component in positron and positronium annihilation were studied by the method of positron diagnostics. An addition of a positron to the -system of a chelate ring is supposed, which makes it possible to qualitatively estimate the basicities of the complexes. Annihilation of positrons and halogen-containing positronium -diketonates is accompanied by the formation of a protonated complex; for -organylthioacetylacetonates, annihilation follows the inhibition mechanism. 相似文献