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A. V. Goltsev K. V. Dyakonov N. F. Kartenko L. A. Kulakova V. V. Popov É. Z. Yakhkind Ya. M. Mukovskii V. P. Dyakonov 《Physics of the Solid State》2005,47(11):2102-2105
The acoustical, resistive, and magnetic properties of a La0.75Sr0.25MnO3 lanthanum manganite single crystal are investigated in the temperature range involving the second-order magnetic phase transition. The acoustical measurements are performed by the pulse-echo method in the frequency range 14–90 MHz. It is found that, as the temperature decreases, the velocity of a longitudinal acoustic wave propagating along the [111] axis in the single crystal drastically increases at temperatures below the critical point of the magnetic phase transition. No dispersion of the acoustic velocity is revealed. A sharp increase in the acoustic velocity is accompanied by the appearance of an acoustical absorption peak. The observed effects are discussed with due regard for the interaction of acoustic waves with the magnetic moments of the manganese ions. 相似文献
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A. V. Goltsev 《Zeitschrift für Physik B Condensed Matter》1994,93(4):425-430
The acoustoelectric effect is studied in normal and mixed superconducting states of an anisotropic metal. We find that if the superconducting gap is anisotropic and the Fermi surface contains both electron-like and holelike parts, then the acoustoelectric voltage can sharply change sign when transited from the normal to superconducting state. The affect of superconducting fluctuations on the acoustoelectric current is also investigated. 相似文献
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Recently a discontinuous percolation transition was reported in a new "explosive percolation" problem for irreversible systems [D. Achlioptas, R. M. D'Souza, and J. Spencer, Science 323, 1453 (2009)] in striking contrast to ordinary percolation. We consider a representative model which shows that the explosive percolation transition is actually a continuous, second order phase transition though with a uniquely small critical exponent of the percolation cluster size. We describe the unusual scaling properties of this transition and find its critical exponents and dimensions. 相似文献
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Vasilij Lebedev 《Discrete Applied Mathematics》2006,154(15):2167-2177
We consider the minmax regret (robust) version of the problem of scheduling n jobs on a machine to minimize the total flow time, where the processing times of the jobs are uncertain and can take on any values from the corresponding intervals of uncertainty. We prove that the problem in NP-hard. For the case where all intervals of uncertainty have the same center, we show that the problem can be solved in O(nlogn) time if the number of jobs is even, and is NP-hard if the number of jobs is odd. We study structural properties of the problem and discuss some polynomially solvable cases. 相似文献
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Yu. V. Ilisavskii A. V. Goltsev K. V. Dyakonov N. F. Kartenko V. V. Popov E. Z. Yakhkind V. P. Dyakonov A. V. Klimov 《Journal of Experimental and Theoretical Physics》2002,94(6):1179-1187
A complex of studies of the physical properties of thin lanthanum manganite La0.67Ca0.33MnO3 films were performed for a monolithic layered structure consisting of a LiNbO3 substrate and a La0.67Ca0.33MnO3 thin epitaxial film. For the first time, not only ordinary acoustoelectric (AE) current of charge carriers dragged by a surface acoustic wave, but also longitudinal anomalous AE current, which flowed in a distinguished direction independent of the direction of the surface acoustic wave propagation, was observed. The anomalous AE effect predominated close to the metal-insulator transition, whereas the odd AE effect predominated at high and low temperatures. The sign of the ordinary odd AE effect corresponded to hole conduction of the film. A theoretical analysis showed that the anomalous AE effect is due to a strong film conduction modulation caused by deformation created by the surface acoustic wave. The theoretical results were in close agreement with experiment. The temperature dependences of resistivity ρ(both in the absence of a magnetic field and in fields of up to 3 T), high-frequency magnetic susceptibility, and thermoelectric power were studied. 相似文献
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Three Silver(I) Coordination Polymers Constructed from Flexible Bis(benzimidazole) and Carboxylates Ligands
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Xiao Xiao Wang Yong Guang Liu Kristof Van Hecke Andrey Goltsev Guang Hua Cui 《无机化学与普通化学杂志》2015,641(5):903-910
Under hydrothermal conditions, three new AgI coordination polymers, [Ag(L1)(Hmip)]n ( 1 ), [Ag(L2)0.5(ndc)0.5]n ( 2 ), and {[Ag(L3)0.5(Htbi)] · 0.25H2O}n ( 3 ) [H2mip = 5‐methylisophthalic acid, L1 = 1,4‐bis(2‐methylbenzimidazol‐1‐ylmethyl)benzene, H2ndc = 2,6‐naphthalenedicarboxylic acid, L2 = 1,3‐bis(2‐methylbenzimidazol‐1‐ylmethyl)benzene, H2tbi = 5‐tert‐butyl isophthalic acid, L3 = 1,4‐bis(5,6‐dimethylbenzimidazole)butane] were synthesized by employing flexible bis(benzimidazole) and dicarboxylic acid ligands. Polymer 1 displays a 2D 4‐connected 4L2 underlying net topology with the point symbol of (65.8) in standard representation. Compound 2 possesses a 2D uninodal 4‐connected Shubnikov tetragonal plane net (sql) based on a dinuclear AgI clusters with the point symbol (44.62), which is further extended into a 3D supramolecular framework by π–π interactions. Compound 3 possesses dinuclear molecular complex groups, which form chains by weak Ag–O (2.6 Å) coordination bonds, and further assembled into a 2D supramolecular layer by hydrogen bonds and π–π stacking interactions. These complexes exhibit intense fluorescent emissions in solid state. UV/Vis diffuse reflection spectra and the excellent catalytic activity for the degradation of the congo red azo dye in a Fenton‐like process are discussed. 相似文献
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Ján Majling Vladimír Kremničan Vladimír Kovár Karol Végső Vasilij Šmatko Miroslav Kocifaj 《Chemical Papers》2017,71(11):2167-2171
Carbon thin films oxidation was investigated on-line by high-sensitivity optical transmission (OT) method. The films have been prepared by common vacuum arc discharge and subsequently air oxidized at linear heating rates until temperatures of their complete gasification. The shape of the optical curves acquired was interpreted in light of deduced partial optical changes, each of them being ascribed by simple sigmoidal dependence. The dependencies converted to their derivative form ordered respective to the temperature scale conveniently represent an inter-relationship among the sequentially evolved films’ optical events, considered as being closely related to the individual carbon-replenishing steps. The dependencies correspond well to the ones obtained on thicker films by means of the thermogravimetry (TG) measurements. 相似文献
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Evaluation of chlorophyll fluorescence and membrane injury in the leaves of barley cultivars under osmotic stress 总被引:3,自引:0,他引:3
Kocheva K Lambrev P Georgiev G Goltsev V Karabaliev M 《Bioelectrochemistry (Amsterdam, Netherlands)》2004,63(1-2):121-124
Two physiological tests for screening drought tolerance of barley (Hordeum vulgare, L.) plants are compared in this work. Water deficit is induced by treating the plants' roots with polyethylene glycol (PEG 8000). The relative water content (RWC) of the plants is used as a measure of the water status. Conductometrically determined electrolyte leakage from the leaf tissue demonstrates the membrane injury caused by dehydration. It is shown that the injury index increases with the decrease of the RWC of the leaves. The F(v)/F(m) ratio is employed to assess changes in the primary photochemical reactions of the photosynthetic apparatus after dehydration. The results suggest that PSII is weakly affected by the imposed osmotic stress. The fluorescence behaviour of the examined cultivars is related to their RWC. 相似文献