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1.
N. V. Timofeeva 《Mathematical Notes》2007,82(5-6):677-690
A new compactification of the variety of moduli of stable vector 2-bundles with Chern classes c 1 and c 2 is constructed for the case in which the universal family of stable sheaves with given values of invariants is defined and there are no strictly semistable sheaves. The compactification is a subvariety in the Hilbert scheme of subschemes of a Grassmann manifold with fixed Hilbert polynomial; it is obtained from the variety of bundle moduli by adding points corresponding to locally free sheaves on surfaces which are modifications of the initial surface. Moreover, a morphism from the new compactification of the moduli space to its Gieseker-Maruyama compactification is constructed. 相似文献
2.
Shipovskaya A. B. Mikul'skii G. F. Timofeeva G. N. 《Russian Journal of Applied Chemistry》2004,77(1):148-153
Structurization in cellulose triacetate modified with trifluoroacetic acid vapor and its effect on the optical activity are studied. 相似文献
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The liquid-phase C-alkylation of hidroquinone with isobutene catalyzed by heteropoly acids H3PW12O40, H6P2W18O62 and H6P2W21O71 (HPA) under phase-transfer conditions in a two-phase system, including toluene (upper phase) and HPA dioxane etherate, HPA·xC4H8O12·yH2O, (lower phase) has been studied. 相似文献
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V. L. Antonovskii A. Yu. Kosnikov N. A. Turovskii T. V. Timofeeva S. V. Lindeman Yu. T. Struchkov A. V. Ganyushkin 《Russian Chemical Bulletin》1990,39(1):57-62
It has been found that in the crystalline state in triphenylmethyl hydroperoxide the hydroperoxy group is involved in intermolecular hydrogen-bond formation of the type O-h..., with one C...C -bond in a benzene ring. Conformational analysis and comparison with the results of x-ray structural analysis leads us to conclude that there are very narrow limits on the possible conformations of the COOH group in tert-butyl, cumyl, 1,1-diphenylethyl, and triphenylmethyl hydroperoxides, independent of their aggregation state or the nature of the substituent attached to the COOH group.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 68–73, January, 1990. 相似文献
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The Michael condensation in the series of 5-aryl-3H-furan-2-ones with chalcones containing electron-donating substituents was studied. In the case of ,-unsaturated ketones containing an electrondonating substituent, the reaction does not stop at the stage of formation of 1,5-dicarbonyl compounds but is accompanied by intramolecular cyclodehydration yielding a new series of furo[2,3-b]-4H-pyrans. A mechanism of formation of these products was suggested. The structure of reaction products was proved by IR and 1H NMR spectroscopy. 相似文献
9.
Timofeeva M. N. Matrosova M. M. Reshetenko T. V. Avdeeva L. B. Paukshtis E. A. Budneva A. A. Chuvilin A. L. Likholobov V. A. 《Russian Chemical Bulletin》2002,51(2):243-248
Adsorption of H3PW12O40 from water and organic oxygen-containing solvents (AcOH, Me2CO, MeOH) by carbon mesoporous materials, viz., Sibunit and catalytic filamentous carbons (CFC), was studied. The amount of irreversibly sorbed heteropolyacid is 50—100 mg g–1 of support and decreases in the series of solvents: H2O > Me2CO > AcOH > MeOH. The adsorption capacity of CFC depends on the specific surface, total pore volume, and microstructure of the CFC fiber. 相似文献
10.
T. P. Kofman V. I. Manuilova M. S. Pevzner T. N. Timofeeva 《Chemistry of Heterocyclic Compounds》1975,11(5):612-614
Alkylation of 3,5-dinitro-1,2,4-triazole with -epoxides in aprotic media gave a number of 1-(2-hydroxyalkyl)-3,5-dinitro-1,2,4-triazoles, which readily undergo intramolecular cyclization with elimination of HNO2 to give 5,6-dihydrooxazolo[3,2-b]-1,2,4-triazole derivatives.See [1] for communication I.Translated from Khimiya Geterotsiklicheskih Soedinenii, No. 5, pp. 705–707, May, 1975. 相似文献