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971.
It is shown, using a Born-Oppenheimer model, that the four-body Efimov effect may occur in a system consisting of three identical heavy particles and one light particle, if the light-heavy interaction leads to a zeroenergy two-heavy-one-light bound state.  相似文献   
972.
Spatio temporal dynamics of the positive column of a dc neon glow discharge is studied and investigated experimentally and theoretically. Spatio temporal analysis by means of biorthogonal decomposition method (BOD) gives insights into the mechanism of irregularity and can be employed for characterization of spatio‐ temporal complexity. In the weak nonlinear region, the wave dynamics is approximated by an amplitude equation of the Ginzburg‐Landau equation (CGLE) with complex coefficients and an additional integral term based on a fluid model. In the present work we deal with irregular spatio‐temporal data. A comparison between the numerical analysis of the experimental data and simulation results are studied. A good agreement between the dynamical behaviour for experimental space‐time data and theoretical simulation space‐time results was obtained. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   
973.
The key contribution of electron microscopy methods to condensed matter spectroscopy is undoubtedly spatial resolution. So far this has mainly been manifest through electron energy loss spectroscopy in the 1-eV to 10-keV energy range and has not seriously challenged the dominance of optical, X-ray, and neutron spectroscopy methods over most of the vast field at lower energies. At frequencies up to a few megahertz, corresponding to energies of a few nanoelectron volts and below, direct excitation by pulsed electron beams or electric fields has proved effective. Prospects are discussed for extending spatially resolved spectroscopy to the intermediate energy region, mainly by combining the advantages of electrons with those of photons.  相似文献   
974.
Three novel functionalized polynorbornenes (PNB) with pendant dimethyl carboxylate group (carboxylates—acetate, propionate, and butyrate) are synthesized as a vinyl‐type with a palladium (II) catalyst in high yield. The effects of size of substitutents, molar ratio of monomer to catalyst, solvent polarity, reaction time, and temperature on the polymerization of exo‐norbornene dimethyl propionate were systematically investigated. The low molar ratio and temperature, as well as high polarity of solvent, and long reaction time, are favorable for the enhancement of the monomer conversion, especially, the solvent have an obvious effect on the catalyst activity. The resulting poly(cis‐norbornene‐exo‐2,3‐dimethyl carboxylates) (PNB‐dimethyl carboxylates) show good solubility in common organic solvent and high thermal stability up to 360 °C. The glass transition temperature was detected by DMA at 331, 324, and 318 °C for acetate, propionate, and butyrate, respectively. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3391–3399, 2007  相似文献   
975.
Modification of shungite with polyamines, followed by corss-linking with epoxy compounds, yielded chemically and thermally stable polyfunctional anion exchangers. The effect of the nature of a polyamine and epoxy compounds and of the carbon content of shungites and the process conditions on the ion-exchange properties of the samples obtained was studied.  相似文献   
976.
We survey recent progress achieved in understanding the impact of inelastic processes on coherent backscattering of light from cold atoms that are saturated by a powerful laser field.  相似文献   
977.
Translated from Matematicheskie Zametki, Vol. 50, No. 3, pp. 81–86, September, 1991.  相似文献   
978.
Translated from algebra i Logika, Vol. 30, No. 6, pp. 693–704, November–December, 1991.  相似文献   
979.
980.
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