全文获取类型
收费全文 | 17526篇 |
免费 | 3937篇 |
国内免费 | 5509篇 |
专业分类
化学 | 3904篇 |
晶体学 | 180篇 |
力学 | 1397篇 |
综合类 | 853篇 |
数学 | 12306篇 |
物理学 | 8332篇 |
出版年
2024年 | 125篇 |
2023年 | 398篇 |
2022年 | 444篇 |
2021年 | 455篇 |
2020年 | 316篇 |
2019年 | 428篇 |
2018年 | 335篇 |
2017年 | 572篇 |
2016年 | 640篇 |
2015年 | 788篇 |
2014年 | 1388篇 |
2013年 | 1089篇 |
2012年 | 1532篇 |
2011年 | 1628篇 |
2010年 | 1473篇 |
2009年 | 1470篇 |
2008年 | 1640篇 |
2007年 | 1308篇 |
2006年 | 1209篇 |
2005年 | 1328篇 |
2004年 | 1148篇 |
2003年 | 1040篇 |
2002年 | 763篇 |
2001年 | 847篇 |
2000年 | 670篇 |
1999年 | 546篇 |
1998年 | 453篇 |
1997年 | 390篇 |
1996年 | 374篇 |
1995年 | 381篇 |
1994年 | 369篇 |
1993年 | 275篇 |
1992年 | 260篇 |
1991年 | 235篇 |
1990年 | 264篇 |
1989年 | 210篇 |
1988年 | 54篇 |
1987年 | 40篇 |
1986年 | 20篇 |
1985年 | 23篇 |
1984年 | 16篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 1篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1963年 | 1篇 |
1959年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
61.
62.
63.
采用振荡管式数字密度计分别测定甲醇、乙醇、正丙醇、异丙醇、丁正醇和异丁醇与N-甲基哌嗪组成的二元体系在298.15K下的密度,计算了超额摩尔体积、超额偏摩尔体积、表观摩尔体积、偏摩尔体积等体积性质,从分子相互作用角度讨论了这些二元体系的体积性质的变化规律,为N-甲基哌嗪的开发和研究提供基础数据和信息。 相似文献
64.
Quantum Inequality for Negative Energy Density States of Massive Dirac Field in Four-Dimensional Spacetime 下载免费PDF全文
Negative energy density and the quantum inequality are examined for the Dirac field. A proof is given of the quantum inequality for negative energy densities in the massive Dirac field produced by the superposition of two single particle electron states. 相似文献
65.
ZHANG Yongqian 《数学年刊B辑(英文版)》2005,26(3):379-392
This paper studies the asymptotic behaviour of steady supersonic flow past a piece-wise smooth corner or bend. Under the hypothese that both vertex angle and the total variation of tangent along the boundary are small, it is shown that the solution can be obtained by a modified Glimm scheme, and that the asymptotic behaviour of the solution is determined by the velocity of incoming flow and the limit of the tangent of the boundary at infinity. 相似文献
66.
The authors study the singular integrals under the Hormander condition and the measure not satisfying the doubling condition. At first, if the corresponding singular integral is bounded from L2 to itself, it is proved that the maximal singular integral is bounded from L∞to RBMO except that it is infinite μ-a.e. on Rd. A sufficient condition and a necessary condition such that the maximal singular integral is bounded from L2 to itself are also obtained. There is a small gap between the two conditions. 相似文献
67.
68.
As in other parts of physics, we advocate the interaction approach: experiments ←→ (… are influenced and their importance is determined by … and vice versa) phenomenology ←→ low-energy effective (field) theory ←→ microscopic theory to probe the microscopic origin of gravity, Using the X-g phenomenological framework, we discuss the tests of equivalence principles. The only experimentally unconstrained degree of freedom is the axion freedom. It has effects on the long-range astrophysical/cosmological propagation of electromagnetic waves and can be tested/measured using the future generation of polarization measurement of cosmic background radiation.The verification or refutal of this axionic effect will be a crucial step for constructing an effective theory and probing the microscopic origin of gravity. The interaction of spin with gravity is another important clue for probing the microscopic origin of gravity. The interplay of experiments, phenomenology and effective theory are expounded. An ideal way to reveal the microscopic origin of gravity is to measure the gyrogravitational ratio of particles, Three potential experimental methods are considered. 相似文献
69.
70.
We investigate the structural properties of liquid Sn. With the help of the internal friction (tanФ) method, it is found that a peak appears in the tan Ф - T curve, suggesting that an anomalous discontinuous temperatureinduced structure change may take place in liquid Sn. From the experimental data of pair distribution functions, we calculate the viscosity η and the excess entropy S and it is found that there are a peak of viscosity in the η-T curve and a bend of excess entropy in the S - T curve, which give a positive support to the appearance of the internal-friction peak in the tan Ф- T curve. 相似文献