全文获取类型
收费全文 | 358篇 |
免费 | 39篇 |
国内免费 | 100篇 |
专业分类
化学 | 31篇 |
力学 | 9篇 |
综合类 | 12篇 |
数学 | 318篇 |
物理学 | 127篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 7篇 |
2021年 | 6篇 |
2020年 | 15篇 |
2019年 | 11篇 |
2018年 | 15篇 |
2017年 | 9篇 |
2016年 | 17篇 |
2015年 | 5篇 |
2014年 | 16篇 |
2013年 | 38篇 |
2012年 | 16篇 |
2011年 | 23篇 |
2010年 | 24篇 |
2009年 | 25篇 |
2008年 | 33篇 |
2007年 | 26篇 |
2006年 | 25篇 |
2005年 | 19篇 |
2004年 | 19篇 |
2003年 | 31篇 |
2002年 | 18篇 |
2001年 | 10篇 |
2000年 | 14篇 |
1999年 | 13篇 |
1998年 | 13篇 |
1997年 | 7篇 |
1996年 | 6篇 |
1995年 | 6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 |
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497条查询结果,搜索用时 225 毫秒
51.
The pre-scission neutrons measured in the reactions 16O+181Ta and 19F+178Hf are studied via a Langevin equation coupled with a statistical decay model.We find that because of the mass asymmetry of different entrance channels,the spin distributions of compound nuclei would be different,consequently,the measured neutrons in these two reactions would also different.This means that the entrance channel will affect the particle emission in the fission process of hot nuclei. 相似文献
52.
53.
We present a version of the Sharkovskii cycle coexistence theorem for differential equations. Our earlier applicable version is extended here to hold with the exception of at most two orbits. This result, which (because of counter-examples) cannot be improved, is then applied to ordinary differential equations and inclusions. In particular, if a time-periodic differential equation has -periodic solutions with , for all , then infinitely many subharmonics coexist.
54.
In this article we give a complete global classification of the class QSess of planar, essentially quadratic differential systems (i.e. defined by relatively prime polynomials and whose points at infinity are not all singular), according to their topological behavior in the vicinity of infinity. This class depends on 12 parameters but due to the action of the affine group and re-scaling of time, the family actually depends on five parameters. Our classification theorem (Theorem 7.1) gives us a complete dictionary connecting very simple integer-valued invariants which encode the geometry of the systems in the vicinity of infinity, with algebraic invariants and comitants which are a powerful tool for computer algebra computations helpful in the route to obtain the full topological classification of the class QS of all quadratic differential systems. 相似文献
55.
A model for multiparticle production process in high-energy hadronic collisions is proposed. In the centre of mass (CM) system
of colliding particles the target and the projectile are assumed to pass through each other sharing energies allowed by kinematical
constraints. Thus in app collision the energy associated with each is √S/2 (S being the square of the CM energy) which is taken to be the real variable that governs the number of particles produced.
In the case of hadronnucleus collisions the projectile and the target ofv nucleons lying in a (Lorentz contracted) tube pass through each other sharing energies ⋍ √S
A2, whereS
A ⋍vS. Before the final state particles emerge from these systems, the constituents of the target, i.e.,v nucleons share equally (= √S
A2v) the total energy associated with the target and become the centres from which final state particles stem out. Several results
have been discussed. 相似文献
56.
Z.Wazir 《中国物理C(英文版)》2010,34(10)
I discuss the results from a study of the central 12CC collisions at 4.2 A GeV/c.The data have been analyzed using a new method based on the Random Matrix Theory.The simulation data coming from the Ultra Relativistic Quantum Molecular Dynamics code were used in the analyses.I found that the behavior of the nearest neighbor spacing distribution for the protons,neutrons and neutral pions depends critically on the multiplicity of secondary particles for simulated data.I conclude that the obtained results offer the possibility of fixing the centrality using the critical values of the multiplicity. 相似文献
57.
In this article, we study the existence of infinitely many solutions to the degenerate quasilinear elliptic system-div(h_1(x)|▽u|~(p-2)▽u)=d(x)|u|~(r-2)u+G_u(x,u,v) in Ω,-div(h_2(x)|▽u|~(p-2)▽v)=f(x)|v|~(s-2)v + G_u(x,u,v) in Ω,u=v=0 on ■Ω where Ω is a bonded domain in R~N with smooth boundary ■Ω,N≥2,1 r p ∞,1 s q ∞; h_1(x) and h_2(x) are allowed to have "essential" zeroes at some points inΩ; d(x)|u|~(r-2)u and f(x)|v|~(s-2)v are small sources with Gu(x,u,v), Gv(x,u,v) being their high-order perturbations with respect to(u,v) near the origin, respectively. 相似文献
58.
Existence and multiplicity of positive solutions for a system of difference equations with coupled boundary conditions 下载免费PDF全文
We study the existence and multiplicity of positive solutions for a system of nonlinear second-order difference equations subject to coupled multi-point boundary conditions. 相似文献
59.
卜玉成 《纯粹数学与应用数学》2010,26(6):977-983
在实际问题中存在着Neumann边值情形.为实际需要,运用指标理论和Morse理论研究了渐近线性二阶Hamilton系统在这种情形下解的存在性和多重性问题。 相似文献
60.