全文获取类型
收费全文 | 13714篇 |
免费 | 1010篇 |
国内免费 | 1568篇 |
专业分类
化学 | 2826篇 |
晶体学 | 26篇 |
力学 | 791篇 |
综合类 | 195篇 |
数学 | 10591篇 |
物理学 | 1863篇 |
出版年
2024年 | 17篇 |
2023年 | 154篇 |
2022年 | 151篇 |
2021年 | 243篇 |
2020年 | 335篇 |
2019年 | 356篇 |
2018年 | 328篇 |
2017年 | 373篇 |
2016年 | 395篇 |
2015年 | 349篇 |
2014年 | 625篇 |
2013年 | 1081篇 |
2012年 | 561篇 |
2011年 | 721篇 |
2010年 | 631篇 |
2009年 | 846篇 |
2008年 | 967篇 |
2007年 | 970篇 |
2006年 | 876篇 |
2005年 | 781篇 |
2004年 | 657篇 |
2003年 | 653篇 |
2002年 | 566篇 |
2001年 | 498篇 |
2000年 | 479篇 |
1999年 | 385篇 |
1998年 | 374篇 |
1997年 | 335篇 |
1996年 | 263篇 |
1995年 | 205篇 |
1994年 | 160篇 |
1993年 | 131篇 |
1992年 | 114篇 |
1991年 | 104篇 |
1990年 | 64篇 |
1989年 | 45篇 |
1988年 | 58篇 |
1987年 | 45篇 |
1986年 | 45篇 |
1985年 | 57篇 |
1984年 | 50篇 |
1983年 | 27篇 |
1982年 | 28篇 |
1981年 | 38篇 |
1980年 | 25篇 |
1979年 | 34篇 |
1978年 | 31篇 |
1977年 | 18篇 |
1976年 | 20篇 |
1973年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
11.
The energy per particle BA in nuclear matter is calculated up to high baryon density in the whole isospin asymmetry range from symmetric matter to pure neutron matter.The results,obtained in the framework of the Brueckner-Hartree-Fock approximation with two-and three-body forces,confirm the well-known parabolic dependence on the asymmetry parameterβ=(N?Z)/A(β^2 law)that is valid in a wide density range.To investigate the extent to which this behavior can be traced back to the properties of the underlying interaction,aside from the mean field approximation,the spin-isospin decomposition of BA is performed.Theoretical indications suggest that theβ^2 law could be violated at higher densities as a consequence of the three-body forces.This raises the problem that the symmetry energy,calculated according to theβ^2 law as a difference between BA in pure neutron matter and symmetric nuclear matter,cannot be applied to neutron stars.One should return to the proper definition of the nuclear symmetry energy as a response of the nuclear system to small isospin imbalance from the Z=N nuclei and pure neutron matter. 相似文献
12.
In this paper, we propose a sufficient and necessary condition for the boundedness of all the solutions for the equation with the critical situation that on g and p, where , is periodic and is bounded. 相似文献
13.
《Comptes Rendus Mecanique》2019,347(11):780-792
The present work aims at proposing a new methodology for learning reduced models from a small amount of data. It is based on the fact that discrete models, or their transfer function counterparts, have a low rank and then they can be expressed very efficiently using few terms of a tensor decomposition. An efficient procedure is proposed as well as a way for extending it to nonlinear settings while keeping limited the impact of data noise. The proposed methodology is then validated by considering a nonlinear elastic problem and constructing the model relating tractions and displacements at the observation points. 相似文献
14.
关于 Hilbert积分不等式(英) 总被引:29,自引:0,他引:29
本文通过引入一个适当的形如F(x,y)的正定二次型证明了Hilbert积分不等式可以得到改进.利用这一结果,Widder不等式得到了加强,并且建立了广义的Hardy-Littlewood不等式. 相似文献
15.
An M/G/1 retrial queueing system with additional phase of service and possible preemptive resume service discipline is considered. For an arbitrarily distributed retrial time distribution, the necessary and sufficient condition for the system stability is obtained, assuming that only the customer at the head of the orbit has priority access to the server. The steady-state distributions of the server state and the number of customers in the orbit are obtained along with other performance measures. The effects of various parameters on the system performance are analysed numerically. A general decomposition law for this retrial queueing system is established. 相似文献
16.
Algebra matrix and similarity classification of operators 总被引:1,自引:0,他引:1
ZHANG Zilong & LI Yucheng Department of Mathematics Hebei Normal University Shijiazhuang China 《中国科学A辑(英文版)》2006,49(3):398-409
In this paper, by the Gelfand representation theory and the Silov idempotents theorem, we first obtain a central decomposition theorem related to a unital semi-simple n-homogeneous Banach algebra, and then give a similarity classification of two strongly irreducible Cowen-Douglas operators using this theorem. 相似文献
17.
Paul Bankston 《Archive for Mathematical Logic》2006,45(1):97-112
The Chang-Łoś-Suszko theorem of first-order model theory characterizes universal-existential classes of models as just those
elementary classes that are closed under unions of chains. This theorem can then be used to equate two model-theoretic closure
conditions for elementary classes; namely unions of chains and existential substructures. In the present paper we prove a
topological analogue and indicate some applications. 相似文献
18.
Necessary conditions for the Gâteaux differentiability of the distance function to a set are considered. A series of characterizing results is obtained. 相似文献
19.
We present a new approach to study the convergence of Newton's method in Banach spaces, which relax the conditions appearing in the usual studies. The approach is based on the bound required for the second derivative of the operator involved. An application to a nonlinear integral equation is presented. 相似文献
20.
设函数f(w)为凸区域D内的单叶解析函数,对于2≤n≤8和所有w∈D,本文得到估计式|f(n)(w)/f'(w)|的精确上界.这个结果推广了一些已知的结论. 相似文献