全文获取类型
收费全文 | 430篇 |
免费 | 35篇 |
国内免费 | 58篇 |
专业分类
化学 | 31篇 |
力学 | 9篇 |
综合类 | 12篇 |
数学 | 329篇 |
物理学 | 142篇 |
出版年
2025年 | 1篇 |
2024年 | 6篇 |
2023年 | 2篇 |
2022年 | 8篇 |
2021年 | 6篇 |
2020年 | 15篇 |
2019年 | 12篇 |
2018年 | 16篇 |
2017年 | 9篇 |
2016年 | 17篇 |
2015年 | 5篇 |
2014年 | 21篇 |
2013年 | 39篇 |
2012年 | 16篇 |
2011年 | 23篇 |
2010年 | 24篇 |
2009年 | 26篇 |
2008年 | 34篇 |
2007年 | 26篇 |
2006年 | 27篇 |
2005年 | 20篇 |
2004年 | 18篇 |
2003年 | 32篇 |
2002年 | 20篇 |
2001年 | 10篇 |
2000年 | 16篇 |
1999年 | 13篇 |
1998年 | 13篇 |
1997年 | 7篇 |
1996年 | 6篇 |
1995年 | 7篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1975年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有523条查询结果,搜索用时 62 毫秒
81.
A sample of 1233 events is used to study the general characteristics of {}^{16}O-Em interactions at 4.5 A GeV/c. Multiplicity and angular distributions of slow particles and correlations among them are discussed. The present data are compared with the corresponding results from the interactions of other projectiles at the same energy and also the same projectile at different energies. The results indicate that black particle production is independent of the energy and mass of the projectile, but for grey particles it is dependent on the mass of projectile. 相似文献
82.
83.
Analysis of prompt fission neutron spectrum and multiplicity for 237Np(n,f) in the frame of multi-modal Los Alamos model
下载免费PDF全文

The improved version of Los Alamos model with the multi-modal fission approach is used to analyse the prompt fission neutron spectrum and multiplicity for the neutron-induced fission of 237Np. The spectra of neutrons emitted from fragments for the three most dominant fission modes (standard Ⅰ, standard Ⅱ and superlong) are calculated separately and the total spectrum is synthesized. The multi-modal parameters contained in the spectrum model are determined on the basis of experimental data of fission fragment mass distributions. The calculated total prompt fission neutron spectrum and multiplicity are better agreement with the experimental data than those obtained from the conventional treatment of the Los Alamos model. 相似文献
84.
Wenrong DAI 《数学年刊B辑(英文版)》2006,27(3):263-286
In this paper, we study the asymptotic behavior of global classical solutions of the Cauchy problem for general quasilinear hyperbolic systems with constant multiple and weakly linearly degenerate characteristic fields. Based on the existence of global classical solution proved by Zhou Yi et al., we show that, when t tends to infinity, the solution approaches a combination of C1 travelling wave solutions, provided that the total variation and the L1 norm of initial data are sufficiently small. 相似文献
85.
We consider the Dirichlet problem with nonlocal coefficient given by in a bounded, smooth domain Ω⊂Rn (n?2), where Δp is the p-Laplacian, w is a weight function and the nonlinearity f(u) satisfies certain local bounds. In contrast with the hypotheses usually made, no asymptotic behavior is assumed on f. We assume that the nonlocal coefficient (q?1) is defined by a continuous and nondecreasing function satisfying a(t)>0 for t>0 and a(0)?0. A positive solution is obtained by applying the Schauder Fixed Point Theorem. The case a(t)=tγ/q (0<γ<p−1) will be considered as an example where asymptotic conditions on the nonlinearity provide the existence of a sequence of positive solutions for the problem with arbitrarily large sup norm. 相似文献
86.
Zhang Tian‐Wei‐Tian 《Mathematical Methods in the Applied Sciences》2014,37(5):686-697
In this paper, we consider a delayed Hassell–Varley‐type predator–prey model with harvesting on prey. By means of Mawhin's continuation theorem of coincidence degree theory, some new sufficient conditions are obtained for the existence of at least two positive almost periodic solutions for the aforementioned model. To the best of the author's knowledge, so far, the result of this paper is completely new. An example is employed to illustrate the result of this paper. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
87.
Sankaran Viswanath 《代数通讯》2013,41(11):3903-3933
We continue the study of stabilization phenomena for Dynkin diagram sequences initiated in the earlier work of Kleber and the present author. We consider a more general class of sequences than that of this earlier work, and isolate a condition on the weights that gives stabilization of tensor product and branching multiplicities. We show that all the results of the previous article can be naturally generalized to this setting. We also prove some properties of the partially ordered set of dominant weights of indefinite Kac–Moody algebras, and use this to give a more concrete definition of a stable representation ring. Finally, we consider the classical sequences B n , C n , D n that fall outside the purview of the earlier work, and work out some easy-to-describe conditions on the weights which imply stabilization. 相似文献
88.
Holger Brenner 《代数通讯》2013,41(10):3199-3213
Let R denote a two-dimensional normal standard-graded K-domain over the algebraic closure K of a finite field of characteristic p, and let I ? R denote a homogeneous R +-primary ideal. We prove that the Hilbert–Kunz function of I has the form ? (q) = e HK (I)q 2 + γ(q) with rational Hilbert–Kunz multiplicity e HK (I) and an eventually periodic function γ(q). 相似文献
89.
方程w\"-w+f(t,w)=O的Dirichlet边值问题的正解存在性与多解性 总被引:1,自引:0,他引:1
姚庆六 《应用泛函分析学报》2002,4(1):4-9
考察了下列常微分方程的Dirichlet边值问题的正解[w″(t)-w(t) f(t,w(t))=0,0≤t≤1 w(0)=w(1)=0建立了n正解的存在性,其中n是一个任意的自然数。 相似文献
90.
This article considers the Dirichlet problem of homogeneous and inhomogeneous second-order ordinary differential systems. A nondegeneracy result is proven for positive solutions of homogeneous systems. Sufficient and necessary conditions for the existence of multiple positive solutions for inhomogeneous systems are obtained by making use of the nondegeneracy and uniqueness results of homogeneous systems. 相似文献