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1.
Vereshchagin Anatoly N. Karpenko Kirill A. Elinson Michail N. Minaeva Alexandra P. Goloveshkin Alexander S. Hansford Karl A. Egorov Mikhail P. 《Molecular diversity》2020,24(4):1327-1342
Molecular Diversity - A novel five-component diastereoselective synthesis of polysubstituted 2-piperidinones is reported. The Knoevenagel condensation–Michael addition–Mannich cascade... 相似文献
2.
Susana Estopiñá-Durán Liam J. Donnelly Euan B. Mclean Bryony M. Hockin Prof. Alexandra M. Z. Slawin Dr. James E. Taylor 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(15):3950-3956
A combination of pentafluorophenylboronic acid and oxalic acid catalyses the dehydrative substitution of benzylic alcohols with a second alcohol to form new C−O bonds. This method has been applied to the intermolecular substitution of benzylic alcohols to form symmetrical ethers, intramolecular cyclisations of diols to form aryl-substituted tetrahydrofuran and tetrahydropyran derivatives, and intermolecular crossed-etherification reactions between two different alcohols. Mechanistic control experiments have identified a potential catalytic intermediate formed between the aryl boronic acid and oxalic acid. 相似文献
3.
Alexandra Shlapentokh 《Monatshefte für Mathematik》2002,110(4):59-67
Let F be a function field of characteristic over a finite field . Then for any finite set of F-primes S and any , there exists a set of F-primes W of density greater than such that and has a Diophantine definition over . (Here and is defined analogously.) 相似文献
4.
Alexander G. Ramm Alexandra B. Smirnova Angelo Favini 《Annali di Matematica Pura ed Applicata》2003,182(1):37-52
A nonlinear operator equation F(x)=0, F:H→H, in a Hilbert space is considered. Continuous Newton’s-type procedures based on a construction of a dynamical system with
the trajectory starting at some initial point x
0 and becoming asymptotically close to a solution of F(x)=0 as t→+∞ are discussed. Well-posed and ill-posed problems are investigated.
Received: June 29, 2001; in final form: February 26, 2002?Published online: February 20, 2003
This paper was finished when AGR was visiting Institute for Theoretical Physics, University of Giessen. The author thanks
DAAD for support 相似文献
5.
Yu. N. Zakharov S. I. Raevskaya V. Z. Borodin V. G. Kuznetsov I. P. Raevskiĭ 《Physics of the Solid State》2006,48(6):1077-1078
The magnitudes of the temperature hysteresis and diffuse dielectric anomaly corresponding to the transition from the antiferroelectric phase to the ferroelectric phase in PbZr1 ? x TixO3 (0.03 ≤ x ≤ 0.05) ceramics can be reversibly changed by varying the temperatures of heating and cooling in the course of thermocycling. The results obtained indicate that the antiferroelectric-ferroelectric transition in the PbZr1 ? x TixO3 ceramics materials is a smeared first-order phase transition. 相似文献
6.
A. I. Burkhanov P. V. Bondarenko S. I. Raevskaya A. V. Shil’nikov I. P. Raevskiĭ 《Physics of the Solid State》2006,48(6):1114-1116
The dielectric properties of a ceramic and a single crystal of the same composition 0.9NaNbO3-0.1Gd1/3NbO3 (NNG10) with different prehistories of the material are investigated in the low-and infralow-frequency ranges. It is revealed that the dielectric aging of the material based on the NaNbO3 antiferroelectric with a smeared phase transition differs in character from similar phenomena observed in relaxor ferroelectrics. 相似文献
7.
Alexandra Shlapentokh 《Compositio Mathematica》2002,132(1):99-120
Let F be a function field of characteristic p > 2, finitely generated over a field C algebraic over a finite field C
p
and such that it has an extension of degree p. Then Hilbert's Tenth Problem is not decidable over F. 相似文献
8.
Thermal properties of benzoic acids carrying one or two semiperfluorinated alkoxy tails on the aromatic core have been investigated in binary mixtures with the non-liquid crystalline bidirectional trans-1,2-bis(4-pyridyl)ethylene. The hydrogen bonded complexes built from the complementary molecular species show a significantly enhanced mesophase stability compared with the fluorinated acids in their pure states. The mesophase morphologies of the complexes are governed mainly by the number of the partially fluorinated chains grafted to the acid component. Mixed systems comprising the one-chain acids exhibit a smectic C phase followed by a smectic A phase at more elevated temperatures. Incorporation of a second semiperfluorinated chain into the acid leads to the formation of columnar mesophases. These columnar phases of the H-bonded complexes should represent ribbon phases resulting from the collapse of the smectic layers. 相似文献
9.
10.
A. E. Raevskaya A. L. Stroyuk S. Ya. Kuchmii Yu. M. Azhnyuk V. M. Dzhagan M. Ya. Valakh 《Theoretical and Experimental Chemistry》2006,42(3):162-168
The optical characteristics of CdSe nanoparticles, produced in aqueous solutions and polymer films in the reaction of cadmium
chloride and sodium selenosulfate, were studied. The main parameters that make it possible to vary the forbidden band width
were identified. The absorption, photoluminescence, Raman, and nonstationary decolorization spectra of CdSe nanoparticles
of various sizes were analyzed. It was demonstrated that under the conditions of pulsed irradiation the CdSe nanoparticles
are capable of accumulating excess electrons and inducing redox transformations in components of the solution (oxygen, methylviologen,
and sulfite ions).
__________
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 3, pp. 150–155, May–June, 2006. 相似文献