全文获取类型
收费全文 | 10384篇 |
免费 | 1571篇 |
国内免费 | 1244篇 |
专业分类
化学 | 7393篇 |
晶体学 | 118篇 |
力学 | 662篇 |
综合类 | 67篇 |
数学 | 1279篇 |
物理学 | 3680篇 |
出版年
2024年 | 39篇 |
2023年 | 252篇 |
2022年 | 262篇 |
2021年 | 357篇 |
2020年 | 423篇 |
2019年 | 443篇 |
2018年 | 380篇 |
2017年 | 362篇 |
2016年 | 506篇 |
2015年 | 501篇 |
2014年 | 575篇 |
2013年 | 785篇 |
2012年 | 874篇 |
2011年 | 942篇 |
2010年 | 655篇 |
2009年 | 595篇 |
2008年 | 734篇 |
2007年 | 606篇 |
2006年 | 551篇 |
2005年 | 417篇 |
2004年 | 370篇 |
2003年 | 278篇 |
2002年 | 311篇 |
2001年 | 212篇 |
2000年 | 202篇 |
1999年 | 257篇 |
1998年 | 181篇 |
1997年 | 131篇 |
1996年 | 141篇 |
1995年 | 135篇 |
1994年 | 99篇 |
1993年 | 108篇 |
1992年 | 87篇 |
1991年 | 86篇 |
1990年 | 77篇 |
1989年 | 58篇 |
1988年 | 41篇 |
1987年 | 36篇 |
1986年 | 21篇 |
1985年 | 31篇 |
1984年 | 20篇 |
1983年 | 14篇 |
1982年 | 12篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1957年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
991.
992.
993.
994.
995.
G.Y. Gao K.L. Yao M.H. SongZ.L. Liu 《Journal of magnetism and magnetic materials》2011,323(21):2652-2657
First-principles full-potential linearized augmented plane-wave method is used to investigate the electronic structure and magnetic properties of hypothetical zinc-blende and rocksalt LiS, NaS and KS. We find that all the compounds except rocksalt LiS exhibit half-metallic ferromagnetism with an integer magnetic moment of 1.00 μB per formula unit. The ferromagnetism results from the spin-polarization of p states of anion S. Total energies calculations indicate the rocksalt phase is lower in energy than the zinc-blende one. The total energy differences are about 0.38, 0.36 and 0.32 eV per formula unit for LiS, NaS and KS, respectively. Meanwhile, it is shown that rocksalt NaS and KS have the half-metallic gaps of 0.22 and 0.41 eV, respectively, and the half-metallic gaps are 0.03, 0.46 and 0.65 eV for zinc-blende LiS, NaS and KS, respectively. We also find the half-metallicity is robust against the lattice contraction up to 7% and 13% for rocksalt NaS and KS, respectively. Although rocksalt LiS is nonmagnetic and metallic at the equilibrium lattice constant, it shows half-metallic ferromagnetism when the lattice constant is larger than 5.40 Å. 相似文献
996.
In this paper, we propose decoherence-free subspaces (DFSs) of anyon states under two kinds of noises. The forms of collective dephasing and collective rotation noises are introduced. The invariance requirement under these noises give some restrictions of the winding number of anyons. We put forward a scheme to realize the DFS of anyon states in the Kitaev spin-lattice model, and give some discussion of general kinds of anyons. 相似文献
997.
Zhijian Yao 《Mathematical Methods in the Applied Sciences》2014,37(16):2354-2362
This paper deals with a discrete Nicholson's blowflies model with linear harvesting term. By using contraction mapping fixed point theorem, we obtain sufficient conditions for the existence of unique almost periodic positive solution. Moreover, we investigate exponential convergence of the almost periodic positive solution by Lyapunov functional. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
998.
One version of Little’s law, written as $L = \lambda w$ , is a relation between averages along a sample path. There are two others in a stochastic setting; they readily extend to the case where the average waiting time $w$ is infinite. We investigate conditions for the sample-path version of this case to hold. Published proofs assume (our) Eq. (3) holds. It is only sufficient. We present examples of what may happen when (3) does not hold, including one that may be new where $w$ is infinite and $L$ is finite. We obtain a sufficient condition called “weakly FIFO” that is weaker than (3), and through truncation, a necessary and sufficient condition. We show that (3) is sufficient but not necessary for the departure rate to be equal to the arrival rate. 相似文献
999.
We are interested in a robust and accurate domain decomposition algorithm with interface conditions of Robin type on non-matching multiblock grids using a cell functional minimization scheme, which has a good performance on non-orthogonal meshes. In order to treat the non-matching grids at the interface, we introduce the \(L^2\) projection operator to ensure weak continuity of the primary unknown and of the normal flux across the non-matching interface. Furthermore, we prove the wellposedness of local and global problems and obtain as well an error estimate of first order in a discrete \(H^{1}\) -norm only using the \(L^{2}\) projection operator on the non-matching interface, as done in the matching case. Numerical results are presented in confirmation of the theoretical results. 相似文献
1000.
姚裕丰 《纯粹数学与应用数学》2014,(1):1-6
通过计算及归纳的方法,得到了n×n矩阵代数中极大线性无关的反交换2-幂零矩阵的个数,推广了相关文献中的一般线性李代数gl(n)的交换子代数的最大维数这一结论. 相似文献