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排序方式: 共有10000条查询结果,搜索用时 453 毫秒
991.
992.
A new formulation of effective potential for local composite operators is given. The two-fermion condensate \(\langle \bar \Psi \Psi \rangle \) and four-fermion condensate \(\langle \bar \Psi \Psi \bar \Psi \Psi \rangle \) are calculated simultaneously in the Gross-Neveu model up to next-to-the-leading order in 1/N expansion. It is shown that factorization \(\langle \bar \Psi \Psi \bar \Psi \Psi \rangle = C_1 \langle \bar \Psi \Psi \rangle ^2 \) holds only in theN→∞ limit and the non-factorized part of \(\langle \bar \Psi \Psi \bar \Psi \Psi \rangle \) contributed by the order-1/N terms is comparable to \(C_1 \langle \bar \Psi \Psi \rangle ^2 \) when takingN=3. 相似文献
993.
We study the problem of directed polymers (DP) on a square lattice. The distribution of disorder is assumed to be independent but non-Gaussian. We show that for distributions with a power-law tailP() 1/||1+
, where>2, so that the mean and variance are well defined, the scaling exponentv of the DP model depends on in a continuous fashion. 相似文献
994.
995.
Zhang Jian-zu 《Physical review D: Particles and fields》1990,42(5):1455-1458
996.
Zhang Jinhao 《数学学报(英文版)》1988,4(1):1-4
What we want to give in this paper is when is an ideal in function algebras finitely generated in view of subelliptic estimates
of
-Neumann problem. 相似文献
997.
Liansheng Zhang 《应用数学学报(英文版)》1988,4(3):200-206
In this paper, we give an implementable algorithm for minimizing a locally Lipschitz function without constraints, and prove the global convergence under the -acute angle condition. 相似文献
998.
In this paper we discuss the approximation of life distributions by exponential ones. The main results are: (1) F NBUE, where its mean is 1, we have
, 0, where = 1 - 2/2, 2 being the second moment ofF. The inequality is sharp. (2) In the case ofFIFR, the upper bound is
. (3) For the HNBUE class, the upper bound is min
. Furthermore, the improved upper bound is
. In addition, we show
0} |\bar G(t) - e^{ - t} | \leqslant \sqrt {\frac{\rho }{2}} $$
" align="middle" border="0">
, where
(4) For the IMRL class, the upper bound is /(1+) ([1]). Here we give a simple proof.Project supported by the National Natural Science Fund of China. 相似文献
999.
A. Türler H. W. Gäggeler D. T. Jost P. Armbruster W. Brüchle H. Folger F. P. Heßberger S. Hofmann G. Münzenberg V. Ninov M. Schädel K. Sümmerer J. V. Kratz U. Scherer 《Zeitschrift für Physik A Hadrons and Nuclei》1988,331(3):363-364
The isotope254No was produced in the fusion reaction48Ca +208Pb. Using the velocity filter SHIP and radiochemical techniques it was found that the nuclide254No with a half-life of 55 s decays byα, EC, and spontaneous-fission. Deduced partial half-lives are (61±2) s forα-decay, (550 ?160 +370 ) s for EC and [2.2 ?1.0 +2.0 ]×104 s for spontaneous fission. 相似文献
1000.
A method has been designed for the reduction of iodate to iodide in seawater and subsequent determination of total dissolved iodine as iodide by cathodic stripping square wave voltammetry. The pH of the sample is lowered to about 1-2 and iodate is reduced to iodide with sodium sulfite under this acidic condition. The pH of the sample is then raised to 8-9 before the concentration of iodide is measured. 相似文献