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11.
12.
Boris A. Trofimov Ol’ga V. Petrova Lyubov’ N. Sobenina Igor’ A. Ushakov Al’bina I. Mikhaleva Yurii Yu. Rusakov Leonid B. Krivdin 《Tetrahedron letters》2006,47(22):3645-3648
Functionalized pyrrolic enols, 2-(2,2-dicyano-1-hydroxyethenyl)-1-methylpyrroles, synthesized from 2-ethenylpyrroles by a nucleophilic SEt-OH exchange, upon heating (75-142 °C) are readily rearranged to their 3-isomers in near to quantitative yield. The inter or intramolecular auto-protonation of a pyrrole ring by the acidic enol hydroxyl to form a mesomeric pyrrolium cation or zwitterion is suggested to be a key step in the rearrangement. 相似文献
13.
E. M. Moroz W. A. Drozdov V. A. Ushakov A. K. Dzhunusov P. G. Tsyrulnikov 《Reaction Kinetics and Catalysis Letters》1990,41(1):109-114
X-ray diffraction studies of supported Ce/Al2O3 and Pt–Ce/Al2O3 catalysts have shown that besides a bulk phase CeO2 a product of the interaction with the support cerium aluminate having a perovskite structure, is usually formed. Platinum in unreduced modified samples forms an oxide and is statistically distributed in the perovskite phase of cerium aluminate. After reduction, only half of the metal is in the metallic state with a particle size of 10 Å.
, CeO2, - . . 10 Å.相似文献
14.
It is known that a k-strongly parabolic surface in Euclidean space (index of relative nullity is at least k) inherits a k-strongly parabolic metric (index of nullity is at least k). For the definitions of the index of relative nullity (x) and the index of nullity (x) see Sh. Kobayashi and K. Nomizu, Foundations of Differential Geometry, Interscience Publishers, New York (1969), Vol. II, pp. 347–348. The converse is not true. In particular, there exists an analytic, three-dimensional, 1-strongly parabolic metric that does not admit a local isometric immersion into Euclidean space of any dimension in the class of three-dimensional 1-strongly parabolic surfaces. The proof is carried out with the help of the method of exterior Cartan forms.Translated from Ukrainskii Geometricheskii Sbornik, No. 33, pp. 27–37, 1990. 相似文献
15.
The high-resolution 1H and 13C NMR spectra of 1-vinylimidazole complexes with iron group metals were recorded. The contact coupling in these systems was
established in the 1H and 13C NMR spectra. The applicability of the NMR spectra transformed by long-range hyperfine coupling for elucidating the molecular
structure of the ligand was shown.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1430–1433, June, 2005. 相似文献
16.
K.B. Helean S.V. Ushakov A. Navrotsky J. Lian J.M. Farmer 《Journal of solid state chemistry》2004,177(6):1858-1866
High-temperature oxide melt solution calorimetry and Rietveld refinements of powder X-ray diffraction data were used to investigate the structure (Fd3m; Z=8) and energetics of a series of RE2Ti2O7 (RE=Sm-Lu) compounds with the pyrochlore structure as well as La2Ti2O7 with a layered perovskite-type structure. All of the RE-titanates were found to be stable in enthalpy with respect to their oxides. In the pyrochlore series, Lu2Ti2O7 was least stable in enthalpy (ΔHf-ox at 298 K=−56.0±4.0 kJ/mol); the most stable materials were Gd-, Eu-, and Sm2Ti2O7 with ΔHf-ox at 298 K=−113.4±2.7, −106.1±4.2, −115.4±4.2 kJ/mol, respectively. In general, as the radius ratio of the A- to B-site cations, RA/RB, decreases, the pyrochlore structure becomes less stable. The trend of ionic radius of the RE3+ cation vs. ΔHf-ox at 298 K is non-linear and approximately parallels the increasing “resistance” to ion-beam-induced amorphization as RA/RB decreases. 相似文献
17.
18.
Adamovich S. N. Kuznetsova G. A. Ushakov I. A. Mirskova A. N. 《Russian Chemical Bulletin》2016,65(11):2751-2753
Russian Chemical Bulletin - New potentially pharmacologically active complexes of general formula n[(HOCH2CH2)3N—O]·MX2 (M = Zn, Co, Ni, Cu; X = Cl, MeCO2, ArOCH2CO2; n = 1, 2) were... 相似文献
19.
Denis N. Tomilin Lyubov N. Sobenina Marina V. Markova Maxim D. Gotsko Igor A. Ushakov Vladimir I. Smirnov 《合成通讯》2013,43(14):1652-1661
5-Acylethynylpyrrole-2-carbaldehydes have been synthesized from the protected pyrrole-2-carbaldehydes by their transition-metal-free topochemical mechanoactivated ethynylation with acylbromoacetylenes in a solid Al2O3 medium (room temperature, 6 h, 41–54% yields). 相似文献
20.
Vereshchagin Anatoly N. Karpenko Kirill A. Elinson Michail N. Goloveshkin Alexander S. Ushakov Ivan E. Egorov Mikhail P. 《Research on Chemical Intermediates》2018,44(9):5623-5634
Research on Chemical Intermediates - A novel four-component stereoselective synthesis of polysubstituted piperidines is reported. The Knoevenagel–Michael–Mannich cascade of two... 相似文献