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31.
D. V. Shishkin E. R. Mukhamed’yarova N. Z. Baibulatova V. A. Dokichev Yu. V. Tomilov 《Chemistry of Natural Compounds》2007,43(3):293-297
Diastereomers of N-(2-(1-adamantyl)-2-hydroxyethyl)cytisine were synthesized by reduction of N-(2-(1-adamantyl)-2-oxoethyl)cytisine with NaBH4. Their structures were established using x-ray structure analysis.
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 244–247, May–June, 2007. 相似文献
32.
O. V. Shishkin 《Monatshefte für Chemie / Chemical Monthly》1996,127(8-9):883-886
Summary The molecular geometry of 4-oxo derivatives of 1,4-dihydropyridine, 1,4-dihydropyrimidine, 1,4-dihydropyridazine, and 1,4-dihydro-1,3,5-triazine has been calculated by the semi-empirical quantum-chemical AM1 method. It could be shown that the dihydrocycle in these compounds is not conformationally rigid. Changing the angle between the endocyclic double bond planes ±15° causes less than 1 kcal/mol increase of energy.
Konformative Flexibilität von 1,4-Dihydroazin-carbonyl-Derivaten (Kurze Mitt.)
Zusammenfassung Die molekulare Geometrie von 4-Oxo-Derivaten von 1,4-Dihydropyridin, 1,4-Dihydropyrimidin, 1,4-Dihydropyridazin und 1,4-Dihydro-1,3,5-triazin wurde mittels der semiempirischen quantenchemischen AM1-Methode berechnet. Es konnte gezeigt werden, daß der zweifach hydrierte Ring in diesen Verbindungen nicht starr ist. Eine Änderung des Winkels zwischen den Ebenen der endocyclischen Doppelbindungen um ±15° bewirkt eine Energieerhöhung von weniger als 1 kcal/mol.相似文献
33.
N. N. Kolos V. D. Orlov D. Arisa O. V. Shishkin Yu. T. Struchkov N. P. Vorob'eva 《Chemistry of Heterocyclic Compounds》1996,32(1):78-85
By the reaction of 4-nitro-1,2 phenylenediamine with 1-(p-R-phenyl)-3-(4-nitrophenyl)propenones, Michael adducts with a 1:2 composition have been obtained. A stagewise scheme is proposed for the formation of these compounds. The structure of one of the products has been established by means of x-ray structure analysis.Deceased 相似文献
34.
Use of a Scanner and Digital Image-Processing Software for the Quantification of Adsorbed Substances
Yu. L. Shishkin S. G. Dmitrienko O. M. Medvedeva S. A. Badakova L. N. Pyatkova 《Journal of Analytical Chemistry》2004,59(2):102-106
The possibility of using a desktop scanner and digital image-processing software for the numerical evaluation of the color intensity of substances adsorbed on polyurethane foam is studied. The method is based on scanning colored samples of polyurethane foam using a desktop scanner, processing the color images using Adobe Photoshop as a graphics editor, and building calibration plots of the luminosity of the selected channel (R, G, or B) as a function of the concentration of the test compound using the Origin software. It has been found that the calibration plots are described by a first-order exponential decay function. The advantages of the method are its high performance, rapidity, and the possibility of mathematical processing of the results. It has been found that substances adsorbed on polyurethane foam can be determined with the use of a scanner and the corresponding image-processing software with the same sensitivity as with the use of diffuse-reflectance spectroscopy. 相似文献
35.
O. V. Shishkin 《Russian Chemical Bulletin》1996,45(8):1833-1835
Molecular and electronic structures of 1,2-dihydropyridine, 1,2- and 1,6-dihydropyrimidine, and their oxo, imino, and methylene derivatives were studied by the semiempirical quantum-chemical AM1 method. In all compounds, the heterocycle exhibits a high conformational flexibility. The transition from a planar equilibrium conformation to a distorted sofa conformation with the =C-NH-C-C(N)= torsion angle of ±20° causes an increase in the energy by less than 1.7 kcal mol–1. All molecules have similar -electronic structures, which, apparently, determines the similarity in their conformational behavior. The bending strain and the nonaromatic character of the cyclic -system are the factors that stabilize the nonplanar conformation of the ring in unsubstituted dihydroazines and ylide derivatives, respectively.Translated fromIzvestiva Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1934–1937, August, 1996. 相似文献
36.
K. L. Cherkasova V. S. Bogdanov V. A. Dorokhov O. V. Shishkin 《Russian Chemical Bulletin》1996,45(6):1437-1439
4-Methylthiopyrido[1,2-α]pyrimidin-2-one and 2-hydroxypyrido[1,2-α]pyrimidine-4-thione derivatives were synthesized by the addition ofN-(4-R-pyrid-2-yl)acetoacetamides (R = H, Me) to CS2 under phase-transfer conditions followed by the alkylation of the reaction products with Mel. The molecular structure of 3-acetyl-4-methylthiopyrido[1,2-α]pyrimidin-2-one is established by X-ray analysis. 相似文献
37.
R. R. Shakirov L. I. Vlasova D. V. Shishkin N. N. Yarmukhamedov N. Z. Baybulatova D. G. Semesko V. A. Dokichev Yu. V. Tomilov 《Russian Chemical Bulletin》2005,54(7):1737-1743
5-Nitropentan-2-one reacts with methylamine and formaldehyde according to the Mannich reaction pattern to give 5-hexahydropyrimidinylcarbonyl-substituted
1-nitro-3,7-diazabicyclo[3.3.1]nonane in one experimental stage. When methyl 3-R-4-nitrobutanoates are used, the reaction
stops after the formation of substituted 5-nitrohexahydropyrimidines in 40–98% yields.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1687–1693, July, 2005. 相似文献
38.
D. P. Kostomarov F. S. Zaitsev A. A. Luk’yanitsa A. G. Shishkin F. A. Anikeev V. V. Zlobin 《Moscow University Computational Mathematics and Cybernetics》2013,37(2):55-60
The concept, functional capabilities, graphic interface, and application technology for the NNTMM code (Neural Network Tool for Mathematical Modeling), designed for analyzing large amounts of experimental and computational data in an interactive mode, are described. The software can be used to solve a wide range of applied problems where automated extraction of meaningful information from randomly presented data is required, along with data classification, clear representation of established relationships and dependences, analysis of parameter importance, and prediction. Examples of using the NNTMM code to analyze data in controlled nuclear fusion problems are presented. 相似文献
39.
40.
Paimushin V. N. Firsov V. A. Gazizullin R. K. Kholmogorov S. A. Shishkin V. M. 《Mechanics of Composite Materials》2019,55(4):435-454
Mechanics of Composite Materials - A technique is developed for identifying the hereditary properties of technical rubber in short-term shear creep from the experimental shift the center of damped... 相似文献