全文获取类型
收费全文 | 92288篇 |
免费 | 11566篇 |
国内免费 | 6581篇 |
专业分类
化学 | 51784篇 |
晶体学 | 675篇 |
力学 | 4155篇 |
综合类 | 1339篇 |
数学 | 17364篇 |
物理学 | 35118篇 |
出版年
2024年 | 119篇 |
2023年 | 738篇 |
2022年 | 1775篇 |
2021年 | 2859篇 |
2020年 | 2435篇 |
2019年 | 2387篇 |
2018年 | 2076篇 |
2017年 | 2520篇 |
2016年 | 3375篇 |
2015年 | 3275篇 |
2014年 | 4136篇 |
2013年 | 6751篇 |
2012年 | 4795篇 |
2011年 | 5348篇 |
2010年 | 4721篇 |
2009年 | 5763篇 |
2008年 | 5859篇 |
2007年 | 6267篇 |
2006年 | 5270篇 |
2005年 | 4068篇 |
2004年 | 3709篇 |
2003年 | 3368篇 |
2002年 | 5524篇 |
2001年 | 2926篇 |
2000年 | 2282篇 |
1999年 | 2026篇 |
1998年 | 1822篇 |
1997年 | 1494篇 |
1996年 | 1395篇 |
1995年 | 1249篇 |
1994年 | 1031篇 |
1993年 | 1016篇 |
1992年 | 899篇 |
1991年 | 697篇 |
1990年 | 547篇 |
1989年 | 428篇 |
1988年 | 537篇 |
1987年 | 349篇 |
1986年 | 335篇 |
1985年 | 433篇 |
1984年 | 334篇 |
1983年 | 186篇 |
1982年 | 366篇 |
1981年 | 552篇 |
1980年 | 483篇 |
1979年 | 495篇 |
1978年 | 397篇 |
1977年 | 292篇 |
1976年 | 253篇 |
1973年 | 172篇 |
排序方式: 共有10000条查询结果,搜索用时 546 毫秒
221.
本文提出从高分辨电子显微像中,利用光学、全息和部分相干等方法,提取传递函数,制作相位和振幅滤波器,实现解卷,提高高分辨电子显微像的分辨率. 相似文献
222.
M. Faucher D. Garcia E. Antic-Fidancev M. Lemaitre-Blaise 《Journal of Physics and Chemistry of Solids》1989,50(12)
Some structural and spectroscopic features of rare earth orthoaluminates are examined.The trigonal→ orthorhombic transition is studied in a series of NdxSm1−xAlO3 compounds. The evolution of the crystal structure is followed by X-ray analysis and optical absorption. The free ion and crystal field parameters of Nd3+ (4f3 configuration) are determined in LuAlO3:Nd3+.The anomaly of the calculated splitting of the
levels is slight, but well characterized in NdAlO3. The spin correlated crystal field and orbitally correlated crystal field models are tested as well as an empirical correction which was proposed earlier. 相似文献
223.
224.
In different regimes of exposure of metals to pulsed laser radiation, we show the role played by the liquid-drop phase formed from the target material in a laser-induced erosion plume due to bulk vaporization, in the dynamics of this plume. For some metals, the ranges of power densities of the acting laser radiation, at which the condensed-phase particles influence the passage of laser radiation to the target surface, have been determined experimentally. The mechanism of realization of a low-threshold breakdown has been revealed. 相似文献
225.
Zhaohui Wang 《Thermochimica Acta》2004,414(1):31-33
Microcalorimetric measurements of excess molar enthalpies, at 298.15 K, are reported for the four binary systems formed by mixing 1-hexene with the cycloalkanes: cyclohexane and methylcyclohexane, and with the aromatic hydrocarcons: benzene and toluene. Smooth Redlich-Kister representations of the results are presented. It was found that the Liebermann-Fried model also provided good representations of the results. 相似文献
226.
227.
S. Mancini D. Vitali V. Giovannetti P. Tombesi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(3):417-422
We show that the optomechanical coupling between an optical cavity mode and two movable cavity mirrors is able to entangle
two different macroscopic oscillation modes of the mirrors. This continuous variable entanglement is maintained by the light
bouncing between the mirrors and is robust against thermal noise. In fact, it could be experimentally demonstrated using present
technology.
Received 2 September 2002 / Received in final form 10 October 2002 Published online 7 January 2003 相似文献
228.
229.
B. Saha S. Bhattacharyya T. K. Mukherjee P. K. Mukherjee 《International journal of quantum chemistry》2003,92(5):413-418
In the framework of nonrelativistic variational formalism a new type of basis set is proposed, to estimate separately the effect of radial and angular correlations on the ground‐state energy for helium isoelectronic sequence H? to Ar16+. Effect of radial correlation is incorporated by using multiexponential functions arising from product basis sets suitably formed out of Slater‐type one‐particle orbitals. The angular correlation can be switched on by incorporating an expansion in terms of basis involving interparticle coordinates. With a set of six‐term Slater‐type one‐particle basis and five‐term interparticle expansion, the ground‐state energy of helium is estimated as ?2.9037236 (a.u.) compared with the multiterm variational estimates ?2.9037244 (a.u.) due to Pekeris and Thakkar and Smith and Drake. Matrix elements of different operators in the ground state have been calculated and found to be in good agreement with available accurate results. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003 相似文献
230.
研究非Chetaev型变质量非完整系统的Lie对称性与Noether对称性以及其间的 关系,给出Lie对称性导致Noether对称性以及Noether对称性导致Lie对称性的条件. 相似文献