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951.
A. A. Rogachev 《Physics of the Solid State》1998,40(5):855-857
Excitons in many-valley semiconductors form molecules consisting of four and more excitons. The degeneracy factor g of the conduction band in germanium is 8, and in silicon g=12. As in acceptors, the hole ground state in excitons is fourfold degenerate. The same is valid for exciton molecules, because
they are quantum objects with spherical symmetry. The exciton binding energy in molecules is close to that in exciton-liquid
droplets. Experimental evidence is considered for the existence, besides biexcitons, of stable exciton molecules consisting
of three and four, and, possibly, 11 and 12 excitons. Molecules containing from five to ten excitons are apparently unstable.
Fiz. Tverd. Tela (St. Petersburg) 40, 929–931 (May 1998) 相似文献
952.
953.
954.
955.
D. T. Satybaldyeva M. Yu. Mukhamedzhanova A. A. Sarymsakov Yu. T. Tashpulatov 《Chemistry of Natural Compounds》1998,34(3):322-325
The results are given of a study of the rheological properties of concentrated solutions of CNC and agar-agar and the influence of their quantitative ratio on the anomalous flow behavior of their solutions. A hypothesis is put forward of the formation of intermolecular associates from CMC and agar-agar which leads to the formation of a stronger structural network of solutions of the initial polysaccharides.Institute of the Physics and Chemistry of Polymers, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (371) 1 44 26 61. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 357–361, May–June, 1998. 相似文献
956.
V. É. Distanov A. G. Kirdyashkin 《Journal of Applied Mechanics and Technical Physics》1998,39(1):85-90
In model experiments, the layer of melt bounded by the crystallization front and the heater for heating the diaphragm in a
growing furnace is shown to determine crystal growth by the Stockbarger method under conditions of induced convection and
also to control the crystallization process. The free volume of the melt exerts no effect on its hydrodynamic and thermal
structures. Optimum values of the exposure time are estimated for constant maximum and minimum velocities of modulated rotation
of the growing ampoule.
Institute of Mineralogy and Petrography, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from
Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 1, pp. 98–104, January–February, 1998. 相似文献
957.
T. A. Zhakatakev 《Journal of Applied Mechanics and Technical Physics》1993,34(4):535-537
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, No. 4, pp. 97–99, July–August, 1993. 相似文献
958.
A. M. Osharin 《Radiophysics and Quantum Electronics》1998,41(4):295-300
Attenuation of millimeter waves in dry snowfalls is numerically simulated with allowance for the actual shape of snowflakes.
It is shown that for moderate-intensity snowfalls the values of attenuation cross-sections averaged over the snowflake orientations
are well approximated by power-law function depending on the equivalent diameter of the snowflakes. This allows us to obtain
an analytical expression for the attenuation coefficient of a plane electromagnetic wave by snowfall for size distributions
of particles of the gamma-distribution type and its modifications.
Radiophysical Research Institute, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika,
Vol. 41, No. 4, pp. 446–455, April, 1998. 相似文献
959.
A. S. Dmitriev 《Radiophysics and Quantum Electronics》1998,41(12):1013-1021
The chaotic synchronization phenomenon is studied from the information point of view. Synchronization of a chaos receiver
by a chaos source is considered as copy recovery of the chaotic signal transmitted by the source. The main idea of this paper
is to show that the necessary condition of chaotic synchronization is not the level of physical action of one system on another
but the transmission of a certain volume of information on the chaotic process and, therefore, the capacity of the “communication
channel” between the source and the receiver.
This work was presented at the Summer Workshop “Dynamic Days” (Nizhny Novgorod, June 30–July 2, 1998).
Institute of Radioengineering and Electronics of the Russian Academy of Sciences, Moscow, Russia. Translated from Izvestiya
Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41, No. 12, pp. 1497–1509, December, 1998. 相似文献
960.
J.P. Contour A. Défossez D. Ravelosona A. Abert P. Ziemann 《Zeitschrift für Physik B Condensed Matter》1996,100(2):185-190
An energy model has been used to calculate the critical thickness h c of YBaCuO thin films and YBaCuO based superlattices within an isotropic or anisotropic approximation. The critical thickness of single layers calculated from the anisotropic model (16 nm) is in good agreement with the previously published experimental values which are spread out from 4 to 20 nm. In the case of superlattices, relaxation appears to be governed by the critical thickness of the elementary sub-layers and is then better evaluated through the calculation performed for YBaCuO single layers. XRD measurements on YBa2Cu3O7/PrBa2Cu3?xGaxO7 superlattices grown on {100{ SrTiO3 have evidenced a tetragonal stress in the YBaCuO ab plane which remains expanded when the YBaCuO elementary layer thickness is lower than 4.8 nm (4 YBaCuO cells). However the critical temperature of the shortest period superlattices is only slightly affected by this expanded stress in contrast to the effect of an elastic stress externally applied along the ab plane of YBaCuO thin films. 相似文献