全文获取类型
收费全文 | 86926篇 |
免费 | 598篇 |
国内免费 | 393篇 |
专业分类
化学 | 29465篇 |
晶体学 | 944篇 |
力学 | 6968篇 |
数学 | 32620篇 |
物理学 | 17920篇 |
出版年
2023年 | 93篇 |
2022年 | 151篇 |
2021年 | 161篇 |
2020年 | 179篇 |
2019年 | 242篇 |
2018年 | 10558篇 |
2017年 | 10413篇 |
2016年 | 6350篇 |
2015年 | 1043篇 |
2014年 | 683篇 |
2013年 | 1080篇 |
2012年 | 4270篇 |
2011年 | 11066篇 |
2010年 | 5997篇 |
2009年 | 6405篇 |
2008年 | 6986篇 |
2007年 | 9122篇 |
2006年 | 535篇 |
2005年 | 1557篇 |
2004年 | 1724篇 |
2003年 | 2103篇 |
2002年 | 1174篇 |
2001年 | 357篇 |
2000年 | 410篇 |
1999年 | 235篇 |
1998年 | 244篇 |
1997年 | 198篇 |
1996年 | 286篇 |
1995年 | 218篇 |
1994年 | 172篇 |
1993年 | 184篇 |
1992年 | 172篇 |
1991年 | 148篇 |
1990年 | 129篇 |
1989年 | 150篇 |
1988年 | 145篇 |
1987年 | 147篇 |
1986年 | 131篇 |
1985年 | 150篇 |
1984年 | 161篇 |
1983年 | 119篇 |
1982年 | 139篇 |
1981年 | 136篇 |
1980年 | 148篇 |
1979年 | 134篇 |
1978年 | 136篇 |
1977年 | 102篇 |
1975年 | 77篇 |
1974年 | 85篇 |
1973年 | 78篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
171.
Christian Remling 《Communications in Mathematical Physics》2007,271(1):275-287
I present an example of a discrete Schrödinger operator that shows that it is possible to have embedded singular spectrum and, at the same time, discrete eigenvalues that approach the edges of the essential spectrum (much) faster than exponentially. This settles a conjecture of Simon (in the negative). The potential is of von Neumann-Wigner type, with careful navigation around a previously identified borderline situation. 相似文献
172.
Maxim V. Pavlov 《Communications in Mathematical Physics》2007,272(2):469-505
The algebro-geometric approach for integrability of semi-Hamiltonian hydrodynamic type systems is presented. The class of
symmetric hydrodynamic type systems is defined and the calculation of the associated Riemann surfaces is greatly simplified for this
class. Many interesting and physically motivated examples are investigated. 相似文献
173.
Xinhuan Feng Lei Sun Yange Liu Lingyun Xiong Shuzhong Yuan Guiyun Kai Xiaoyi Dong 《Optical and Quantum Electronics》2004,36(10):919-926
A simple actively mode-locked fiber ring laser is proposed and successfully demonstrated to generate dual-wavelength picosecond pulses with close wavelength spacing using one Bragg grating in standard single-mode fiber. The proposed laser can be made to operate in stable dual-wavelength at room temperature, due to the birefringence characteristic of the FBG induced by transverse strain. Transverse strain loading on the FBG allows the wavelength spacing to be controlled. Generation of stable dual-wavelength pulses with a pulsewidth of 212–234 ps and a tunable wavelength separation from 0.2 to 0.44 nm at a pulse rate of 1.05 GHz was demonstrated. 相似文献
174.
175.
Kwang-Hua W. Chu 《International Journal of Theoretical Physics》2007,46(12):3230-3233
The modified Gross–Pitaevskii equation was derived and solved to obtain the 1D solution in the zero-energy limit. This stationary
solution could account for the dominated contributions due to the kinetic effect as well as the chemical potential in inhomogeneous
Bose gases. 相似文献
176.
Djamel Meraghni Abdelhakim Necir 《Methodology and Computing in Applied Probability》2007,9(4):557-572
The characteristic exponent α of a Lévy-stable law S
α
(σ, β, μ) was thoroughly studied as the extreme value index of a heavy tailed distribution. For 1 < α < 2, Peng (Statist. Probab. Lett. 52: 255–264, 2001) has proposed, via the extreme value approach, an asymptotically normal estimator for the location parameter μ. In this paper, we derive by the same approach, an estimator for the scale parameter σ and we discuss its limiting behavior.
相似文献
177.
178.
Applying tight-binding approximation and spin pairing of like charge carriers in a pair of excitons created in a lattice, the possibility of forming a bound exciton-exciton state is studied. It is found that, provided there exists strong exciton-lattice interaction, such a bound state may be formed and its energy may lie within the valence band deforming the material into a crystalline solid with no energy gap. Lowering of the energy is calculated in naphthalene and anthracene crystals where some experimental results are known. The excess energy released after the formation of such bound state can be adequate, depending on the material, to desorb neutral atoms or eject of electrons from surfaces. 相似文献
179.
180.