全文获取类型
收费全文 | 2980篇 |
免费 | 542篇 |
国内免费 | 403篇 |
专业分类
化学 | 350篇 |
晶体学 | 23篇 |
力学 | 317篇 |
综合类 | 61篇 |
数学 | 2252篇 |
物理学 | 922篇 |
出版年
2024年 | 25篇 |
2023年 | 38篇 |
2022年 | 54篇 |
2021年 | 52篇 |
2020年 | 82篇 |
2019年 | 96篇 |
2018年 | 116篇 |
2017年 | 111篇 |
2016年 | 125篇 |
2015年 | 102篇 |
2014年 | 160篇 |
2013年 | 297篇 |
2012年 | 162篇 |
2011年 | 198篇 |
2010年 | 171篇 |
2009年 | 183篇 |
2008年 | 185篇 |
2007年 | 201篇 |
2006年 | 186篇 |
2005年 | 158篇 |
2004年 | 127篇 |
2003年 | 117篇 |
2002年 | 133篇 |
2001年 | 119篇 |
2000年 | 105篇 |
1999年 | 102篇 |
1998年 | 74篇 |
1997年 | 75篇 |
1996年 | 45篇 |
1995年 | 49篇 |
1994年 | 41篇 |
1993年 | 26篇 |
1992年 | 33篇 |
1991年 | 17篇 |
1990年 | 13篇 |
1989年 | 12篇 |
1988年 | 16篇 |
1987年 | 8篇 |
1986年 | 11篇 |
1985年 | 15篇 |
1984年 | 13篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 12篇 |
1980年 | 9篇 |
1979年 | 10篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1974年 | 3篇 |
1973年 | 3篇 |
排序方式: 共有3925条查询结果,搜索用时 703 毫秒
141.
Tsugunori Nogura 《Topology and its Applications》1983,15(1):65-69
We study the question whether a topological space X with a property can be embedded in a countably compact space X? with the same property . 相似文献
142.
Sheldon M Ross 《Stochastic Processes and their Applications》1976,4(2):167-173
Consider an n-component reliability system having the property that at any time each of its components is either up (i.e., working) or down (i.e., being repaired). Each component acts independently and we suppose that each time the ith component goes up it remains up for an exponentially distributed time having mean μi, and each time it goes down it remains down for an exponentially distributed time having mean υi. We further suppose that whether or not the system itself is up at any time depends only on which components are up at that time. We are interested in the distribution of the time of first system failure when all components are initially up at time zero. In section 2 we show that this distribution has the NBU (i.e., new better than used) property, and in Section 3 we make use of this and other results to obtain a lower bound to the mean time until first system failure. 相似文献
143.
Jan Grandell 《Stochastic Processes and their Applications》1979,8(3):243-255
We consider the classical model for an insurance business where the claims occur according to a Poisson process and where the distribution for the cost of each claim fulfills Cramér's tail-condition. Under these conditions Lundberg's constant R is of fundamental importance for ruin calculations.We derive estimates of R, based on an observation of the insurance business and investigate the statistical properties of those estimates. We further derive bounds and confidence intervals for ruin probabilities. 相似文献
144.
B K Godwal 《Pramana》1982,19(3):225-229
The method of first principle pseudopotential is used to simulate the volume variation of nuclear Grüneisen parameter. The
elements Al and Be, for which Neal’s experimental data exist are investigated. The nuclear Grüneisen obtained from the details
of phonon frequencies are in better agreement with the experimental data as compared to those obtained from approximate Slater
and Dugdale-MacDonald methods, often used in shock wave studies. 相似文献
145.
146.
ZHAN Zhiming LI Weibin YOU Jun XIE Xiaotao & YANG Wenxing .State Key Laboratory of Laser Technology Huazhong University of Science Technology Wuhan China .Department of Physics Huazhong University of Science Technology Wuhan China 《中国科学G辑(英文版)》2004,47(6):649-657
With recent advances in Bose-Einstein condensation (BEC)[1—3], there has beenmuch interest in nonlinear processes in the various disciplines of physics, such asnonlinear multi-wave mixing processes[4]. Now, great efforts are devoted to constructingthe nonlinear quantized models to numerate the energy spectra and eigenstates of thesenonlinear processes[5—8]. But there still remain some problems with regard to interactionsamong several bosonic modes, for example, how to explicitly obtain the… 相似文献
147.
For a crystal film, we consider the Schrödinger operator defined on Bloch functions (with respect to two variables) in a cell. The potential is the sum of two small terms: a function decreasing with respect to the third variable and an operator of rank one. We prove the existence of two levels (eigenvalues or resonances) near the parameter value E=0 and obtain their asymptotic behavior. 相似文献
148.
四阶非线性特征值问题的正解 总被引:6,自引:1,他引:5
本文考虑了四阶非线性特征值问题d4u/dt4=λg(t)f(u,u″),0<t<1,u(0)=u(1)=0,au″(0)-bu″′(0)=0,cu″(1)+du″′(1)=0.其中g(t)∈C((0,1),[0,∞)),f(u,v)∈C([0,∞)×(-∞,0],[0,∞)),a≥0,b≥0,c ≥0,d ≥ 0,且△=ac+ad+bc>0.利用锥压缩与拉伸不动点定理,获得了上述问题正解的存在性结果. 相似文献
149.
Fordyce A. Davidson Bryan P. Rynne 《Journal of Mathematical Analysis and Applications》2004,300(2):491-504
Let TR be a time-scale, with a=infT, b=supT. We consider the nonlinear boundary value problem (2) (4)
u(a)=u(b)=0,