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951.
A. Paesano Jr. S. C. Zanatta S. N. De Medeiros L. F. CÓtica J. B. M. Da Cunha 《Hyperfine Interactions》2005,161(1-4):211-220
We have investigated the mechanosynthesis of gadolinium and yttrium iron garnets by high-energy ball-milling of α-Fe2O3 and Gd2O3 or α-Fe2O3 and Y2O3, respectively, followed by short thermal annealings conducted at moderate temperatures. The samples were characterized by X-ray diffraction and Mössbauer spectroscopy, in order to determine the influence of the milling time and annealing conditions on the final products. For as-milled samples of each rare-earth system, the results revealed the formation of perovskite phases, in relative amounts that depend on the milling time. The formation of garnet phases was observed in as-annealed samples treated at 1000°C for 2 h or 1100°C for 3 h, i.e., at very modest annealing requirements when compared with ordinary solid-state-reaction processes performed without previous high-energy milling. Also, the occurrence was verified of a milling time for which the relative amount of garnet phases formed by annealing was maximized. This time depends on the rare-earth composing the garnet phase and on the annealing temperature. 相似文献
952.
The Nd:YAG laser-induced breakdown of 20 μm glass microspheres was investigated using time-resolved optical shadow and Schlieren images. Time-resolved imaging showed the location of the initial breakdown and the shockwave motion over its first 400 μm of expansion. Measured shockwave velocities were in the range of 1–10 km/s and showed a linear dependency on laser fluence within 30 ns. 相似文献
953.
Hua Ning LIU Wen Peng ZHANG 《数学学报(英文版)》2007,23(5):915-924
The main purpose of this paper is to use the generalized Bernoulli numbers, Gauss sums and the mean value theorems of Dirichlet L-functions between a quadratic residue and its inverse modulo p value formula. to study the asymptotic property of the difference (a prime), and to give an interesting hybrid mean 相似文献
954.
955.
956.
G. D. Andreetti F. Ugozzoli A. G. Giumanini P. Traldi L. Lassiani A. Varnavas 《Journal of chemical crystallography》1991,21(6):721-728
The decomposition of the gaseous positive ions of the title compounds obtained by electron impact have been completely mapped. The X-ray structural determinations of these two substances established their identity definitively and allowed to reveal some interesting features of these molecules of pharmaceutical interest. 相似文献
957.
V. F. Babenko 《Ukrainian Mathematical Journal》1991,43(9):1064-1076
We compute Kolmogorov widths in the space L1 for classes of periodic functions representable in the form of a kernel convolution that does not increase the number of sign changes with values in a given transposition invariant set of functions, and solve the optimization problem for quadrature formulas in these classes.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 43, No. 9, pp. 1135–1148, September, 1991. 相似文献
958.
N. M. Agababyan M. R. Atayan M. Charlet J. Czyżewski E. A. De Wolf K. Dziunikowska A. M. F. Endler Z. Sh. Garutchava H. R. Gulkanyan R. Sh. Hakobyan J. K. Karamyan D. Kisielewska W. Kittel S. S. Mehrabyan Z. V. Metreveli E. C. Oliveira K. Olkiewicz F. K. Rizatdinova E. K. Shabalina L. N. Smirnova M. D. Tabidze L. A. Tikhonova A. V. Tkabladze A. G. Tomaradze F. Verbeure S. A. Zotkin 《Zeitschrift fur Physik C Particles and Fields》1996,71(1):405-414
The NA22 data onπ ? π ? correlations are analyzed in terms of a number of two- and three-dimensional parametrizations (Gaussian space-time, Goldhaber, Bowler string-like, Bertsch hydrodynamical, Kopylov-Podgoretskii, etc.). Contrary to the results obtained for e+e? andµp collisions, the Goldhaber parametrization, as well as string-like models, fail in describing the hadron-hadron data. Better fits are obtained in the framework of surface-emitting fireball-like models, both when including and excluding hydrodynamical expansion of nuclear matter. Our results indicate that pion radiation occurs at earlier stages of matter evolution than in nuclear collisions. 相似文献
959.
R. Buccellato M. M. Michaelis C. A. Dempers A. Prause P. F. Cunningham 《Optics & Laser Technology》1993,25(4)
The concept of a pulsed gas lens is proposed. Potential applications are envisaged and preliminary experiments with pulsed ray refraction are reported. 相似文献
960.