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1.
Phil Diamond Peter Kloeden Victor Kozyakin Alexei Pokrovskii 《Mathematische Nachrichten》1998,191(1):59-81
The finiteness of computer arithmetic can lead to some dramatic differences between the behaviour of a continuous dynamical system and a computer simulation. A thorough rigorous theoretical analysis of what may or what does happen is usually extremely difficult and to date little has been done even in relatively simple contexts. The comparative behaviour of a rotation mapping in the plane and on a uniform lattice in the plane is one such example. Simulations show that the rounding operator applied to a planar rotation mapping more or less preserves the qualitative behaviour of the original mapping, whereas the application of the truncation operator to a planar rotation can lead to quite different dynamical features. In this paper a theoretical justification of the properties of the planar rotation mappings under truncation to a, uniform integer lattice is provided, in particular properties of boundedness and dissipativity are investigated. 相似文献
2.
Borodkin G. I. Popov S. A. Pokrovskii L. M. Shubin V. G. 《Russian Journal of Organic Chemistry》2003,39(5):747-749
Russian Journal of Organic Chemistry - 相似文献
3.
V. A. Pokrovskii Yu. I. Bratushko T. N. Yakubovich G. N. Mel'nichenko 《Theoretical and Experimental Chemistry》1987,23(3):289-293
Thermal deoxygenation under vacuum has been examined for free oxygenated cobalt complexes formed with phenanthroline, histidine, and histamine and also for those attached to aerosil; mass spectrometry has been applied to the products. The free compounds are deoxygenated in accordance with the Roginskii equation f() = (1–)2/3 in a certain range. Deoxygenation for the grafted complexes is described by an equation for nucleation and one-dimensional growth f() = 1–. The kinetic parameters have been determined.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 23, No. 3, pp. 311–317, May–June, 1987. 相似文献
4.
Galina A. Selivanova Leonid M. Pokrovskii Vitaliy D. Shteingarts 《Journal of fluorine chemistry》2004,125(12):1829-1834
Chlorine-containing polyfluorinated anilines and meta-phenylenediamines undergo selective hydrodechlorination easily upon reduction by zinc in aqueous ammonia. A new approach is thus provided to synthetically valuable, partially fluorinated arylamines based on utilizing polyfluorochloroarenes, which are available as intermediates of perfluoroarene production from perchloroarenes. When chlorine atoms are present in positions both ortho and para to the amino group, para chlorine is initially eliminated. Based on this reaction, a one-pot synthesis of partially fluorinated 4-aminopyridines from 3,5-dichlorotrifluoro- and 3-chlorotetrafluoropyridine has been realized. 相似文献
5.
An explicitly solvable model of Mössbauer scattering of rays by a nucleus bound in a harmonic-oscillator potential is constructed. The probability of elastic scattering, which is proportional to the Debye—Waller factor, is calculated in the framework of the explicitly solvable scattering problem. It is assumed that the rms deviation x of the nucleus and the photon wave numberk satisfykxE
/E
, whereE
andE
are typical energy levels of the photon and the oscillator states.St Petersburg State University. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 95, No. 3, pp. 439–430, June, 1993. 相似文献
6.
The interaction of pentafluorobenzaldehyde with RCCl3 (R = Cl, Ph, C6F5) in the presence of threefold molar excess of AlCl3 proceeds with replacing the oxygen atom of the aldehyde group by two chlorine atoms from the CCl3 group and results in the formation of pentafluorobenzylidene chloride. The electrophilic mechanism of the reaction is proposed. 相似文献
7.
M. M. Aleksankin I. P. Samchenko L. I. Fileleeva V. A. Nazarenko V. A. Pokrovskii V. A. Topchii 《Theoretical and Experimental Chemistry》1987,23(2):164-171
The field mass spectra of 18 sulfides, sulfoxides, and sulfones were investigated, and the principles of charge localization in the dissociation and rearrangements of the molecular ions of these compounds were established. A new type of fragmentation leading to the elimination of S+., SO+., and SO2. was observed. A new mechanism, according to which cleavage of two C-S bonds and the formation of one new C-C bond due to radical recombination cocur in the cyclic transition complex, is proposed. Prior migration of alkyl radicals from sulfur to oxygen with subsequent cleavage of the S-O and C-S bonds via the above-mentioned mechanism may also occur in the molecular ions of sulfoxides and sulfones.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 23, No. 2, pp. 172–181, March–April, 1987. 相似文献
8.
Epoxy resin modified with sebacic acid was synthesized. It exhibits improved elastic properties and impact resistance. 相似文献
9.
We find that an electric current I exceeding the threshold value results in torsional strain of o-TaS3 samples with one contact freely suspended. The rotation angle deltavarphi of the free end achieves several degrees and exhibits hysteresis as a function of I. The sign of deltavarphi depends on the I polarity; a polar axis along the conducting chains (the c axis) is pointed out. We associate the effect with surface shear of the charge-density wave (CDW) coupled to the crystal shear. The current-induced torsional strain could be treated in terms of enormous piezoelectric coefficients (>10(-4) cm/V) corresponding to shear. In essence, TaS3 appears to be a ready torsional actuator based on the unique intrinsic property of the CDW. 相似文献
10.
Components of the ethylacetate extract of <Emphasis Type="Italic">Hedysarum theinum</Emphasis> roots
I. V. Nechepurenko N. P. Polovinka O. I. Sal’nikova L. M. Pokrovskii N. I. Komarova N. F. Salakhutdinov S. B. Nechepurenko 《Chemistry of Natural Compounds》2007,43(1):5-9
Isoflavonoids (-)-medicarpin, (-)-vestitol, and formononetin and butylphenols raspberry ketone and rhododendrol were isolated
for the first time from the ethylacetate extract of Hedysarum thienum roots by column chromatography. GC-MS showed that the ethylacetate extract contained fatty acids, the principal ones being
palmitic, linoleic, oleic, behenic, and lignocerinic.
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 6–9, January–February, 2007. 相似文献