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991.
Marco Andreatta Elena Chierici Gianluca Occhetta 《Central European Journal of Mathematics》2004,2(2):272-293
Let X be a Fano variety of dimension n, pseudoindex i
X
and Picard number ρX. A generalization of a conjecture of Mukai says that ρX(i
X
−1)≤n. We prove that the conjecture holds for a variety X of pseudoindex i
X
≥n+3/3 if X admits an unsplit covering family of rational curves; we also prove that this condition is satisfied if ρX> and either X has a fiber type extremal contraction or has not small extremal contractions. Finally we prove that the conjecture holds
if X has dimension five. 相似文献
992.
Green-light-emitting Zn2SiO4:Mn phosphor particles were synthesized by modified large-scale spray pyrolysis using a colloidal solution containing fumed silica particles. The particles had a fine size, filled morphology, spherical shape and non-aggregation characteristics even after post-treatment at 1150 °C. The luminescence characteristics of Zn2SiO4:Mn phosphor particles having spherical shape, such as brightness and decay time under VUV excitation light, were investigated as a function of Mn content. The luminescence intensity exhibits a maximum at 5 mol% Mn-doped powder. The decay time increases consistently with decreasing Mn content and more saturated color coordinates are obtained with the composition having 12 mol% Mn. As a consequence, the 10 mol% Mn-doped powder proved to provide a good combination of favorable luminance and acceptable decay time. The influence of post-treatment temperature on the decay time and photoluminescence characteristics of Zn2SiO4:Mn particles was also investigated. Particles post-treated at 1155 °C had the maximum photoluminescence intensity, which was identical to 113% that of the commercial product, and a comparable decay time of 5.8 ms. PACS 81.20.Rg; 78. 55.Hx; 78.40.Ha; 81.05.Hd; 81.40.Tv 相似文献
993.
994.
995.
E. Yu. Daniyarova I. V. Kazatchkov V. N. Remeslennikov 《Journal of Mathematical Sciences》2005,131(6):6015-6022
This article is the fourth part of the series of papers whose aim is the construction of algebraic geometry over metabelian
Lie algebras.
__________
Translated from Sovremennaya Matematika i Ee Prilozheniya (Contemporary Mathematics and Its Applications), Vol. 14, Algebra,
2004. 相似文献
996.
The load-carrying capacity of circular plates made of a fiber-reinforced composite and loaded with axisymmetric transverse forces under axisymmetric boundary conditions is investigated. The plates can be freely supported or clamped along their contour. To the known yield condition used, in the plane of main bending moments, there correspond irregular hexagons, which depend on the mechanical properties of composite constituents and some characteristic geometrical parameters. It is shown that, depending on the ratio of ultimate radial and circumferential bending moments, in the plastic state, the circular plates (the central part of the clamped plates) take the form of a cone or a frustum of cone. For each of the cases, the limit load is found, which is a function of the above-mentioned mechanical parameters. The statically allowable fields of bending moments and the corresponding allowable fields of deflection rates are determined. The solutions found are exact. Special cases for the freely supported plates are analyzed, and the results obtained are presented in the form of graphs.__________Translated from Mekhanika Kompozitnykh Materialov, Vol. 41, No. 2, pp. 177–192, March–April, 2005. 相似文献
997.
Dinesh Topwal U. Manju Sugata Ray S. Raj D. D. Sarma S. R. Krishnakumar M. Bertolo S. La Rosa G. Cautero 《Journal of Chemical Sciences》2006,118(1):87-92
Disordered Sr2FeMoO6 shows a drastic reduction in saturation magnetization compared to highly ordered samples, moreover magnetization as a function
of the temperature for different disordered samples shows qualitatively different behaviours. We investigate the origin of
such diversity by performing spatially resolved photoemission spectroscopy on various disordered samples. Our results establish
that extensive electronic inhomogeneity, arising most probably from an underlying chemical inhomogeneity in disordered samples, is
responsible for the observed magnetic inhomogeneity. It is further pointed out that these inhomogeneities are connected with
composition fluctuations of the type Sr2Fe1+x
Mo1-x
O6 with Fe-rich (x > 0) and Mo-rich (x < 0) regions.
Dedicated to Prof J Gopalakrishnan on his 62nd birthday. 相似文献
998.
999.
Summary Vezetéknév 相似文献
1000.
The physico-chemical properties and reactivity tested by hydrogen reduction have been studied for two series of NiO-ZnO mixed oxides of various composition. The solid nickel oxide or zinc oxide in interaction with the solution of nitrate of the second component were used as the precursors in each series. The differences in some physico-chemical parameters of the samples in both series were correlated with their reduction behaviour, followed both in iso- and non-isothermal regime. Moreower, the influence of various factors modifying the reactivity of mixed oxides was also investigated and the results were compared with those obtained from earlier studied analogous systems of quite different origin.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献