全文获取类型
收费全文 | 13141篇 |
免费 | 2749篇 |
国内免费 | 1348篇 |
专业分类
化学 | 2987篇 |
晶体学 | 172篇 |
力学 | 1868篇 |
综合类 | 168篇 |
数学 | 2254篇 |
物理学 | 9789篇 |
出版年
2024年 | 13篇 |
2023年 | 135篇 |
2022年 | 242篇 |
2021年 | 330篇 |
2020年 | 405篇 |
2019年 | 317篇 |
2018年 | 318篇 |
2017年 | 437篇 |
2016年 | 515篇 |
2015年 | 486篇 |
2014年 | 736篇 |
2013年 | 965篇 |
2012年 | 853篇 |
2011年 | 897篇 |
2010年 | 834篇 |
2009年 | 866篇 |
2008年 | 869篇 |
2007年 | 827篇 |
2006年 | 833篇 |
2005年 | 768篇 |
2004年 | 781篇 |
2003年 | 645篇 |
2002年 | 600篇 |
2001年 | 492篇 |
2000年 | 478篇 |
1999年 | 406篇 |
1998年 | 355篇 |
1997年 | 278篇 |
1996年 | 241篇 |
1995年 | 196篇 |
1994年 | 176篇 |
1993年 | 137篇 |
1992年 | 109篇 |
1991年 | 101篇 |
1990年 | 91篇 |
1989年 | 97篇 |
1988年 | 76篇 |
1987年 | 51篇 |
1986年 | 59篇 |
1985年 | 42篇 |
1984年 | 30篇 |
1983年 | 16篇 |
1982年 | 25篇 |
1981年 | 21篇 |
1980年 | 18篇 |
1979年 | 16篇 |
1978年 | 15篇 |
1977年 | 8篇 |
1976年 | 7篇 |
1975年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Employing positive-definiteness arguments we analyse Boson field states, which combine classical and quantum mechanical features (signal and noise), in a constructive manner. Mathematically, they constitute Bauer simplexes within the convex, weak-*-compact state space of the C*-Weyl algebra, defined by a presymplectic test function space (smooth one-Boson wave functions) and are affinely homeomorphic to a state space of a classical field. The regular elements are expressed in terms of weak distributions (probability premeasures) on the dual test function space. The Bauer simplex arising from the bare vacuum is shown to generalize the quantum optical photon field states with positive P-functions. 相似文献
102.
103.
D. Baleanu 《Czechoslovak Journal of Physics》2003,53(11):971-976
The variational formulation of the Schrödinger field was investigated and the applicability of the chain method was analyzed. Using Batalin-Fradkin-Tyutin formalism a gauge invariant theory was constructed. 相似文献
104.
105.
根据实验室研制的磁流体密封装置,采用自制煤油基磁流体,通过多次实验初步探索到磁体泄放压与外磁场之间的变化规律。 相似文献
106.
107.
Myron W. Evans 《Foundations of Physics Letters》2003,16(6):513-547
A generally covariant wave equation is derived geometrically for grand unified field theory. The equation states most generally that the covariant d'Alembertian acting on the vielbein vanishes for the four fields which are thought to exist in nature: gravitation, electromagnetism, weak field and strong field. The various known field equations are derived from the wave equation when the vielbein is the eigenfunction. When the wave equation is applied to gravitation the wave equation is the eigenequation of wave mechanics corresponding to Einstein's field equation in classical mechanics, the vielbein eigenfunction playing the role of the quantized gravitational field. The three Newton laws, Newton's law of universal gravitation, and the Poisson equation are recovered in the classical and nonrelativistic, weak-field limits of the quantized gravitational field. The single particle wave-equation and Klein-Gordon equations are recovered in the relativistic, weak-field limit of the wave equation when scalar components are considered of the vielbein eigenfunction of the quantized gravitational field. The Schrödinger equation is recovered in the non-relativistec, weak-field limit of the Klein-Gordon equation). The Dirac equation is recovered in this weak-field limit of the quantized gravitational field (the nonrelativistic limit of the relativistic, quantezed gravitational field when the vielbein plays the role of the spinor. The wave and field equations of O(3) electrodynamics are recovered when the vielbein becomes the relativistic dreibein (triad) eigenfunction whose three orthonormal space indices become identified with the three complex circular indices (1), (2), (3), and whose four spacetime indices are the indices of non-Euclidean spacetime (the base manifold). This dreibein is the potential dreibein of the O(3) electromagnetic field (an electromagnetic potential four-vector for each index (1), (2), (3)). The wave equation of the parity violating weak field is recovered when the orthonormal space indices of the relativistic dreibein eigenfunction are identified with the indices of the three massive weak field bosons. The wave equation of the strong field is recovered when the orthonormal space indices of the relativistic vielbein eigenfunction become the eight indices defined by the group generators of the SU (3) group. 相似文献
108.
Mathematical Notes - 相似文献
109.
K. L. Janssens B. Partoens F. M. Peeters 《Physica E: Low-dimensional Systems and Nanostructures》2004,21(2-4):349
We investigated theoretically the influence of strain on the exciton in both single and three vertically coupled self-assembled quantum dot systems in the presence of a perpendicular magnetic field. For the single disk, we find that the heavy-hole exciton is the ground state, while for the system of three stacked disks, the light hole state was found to be lower in energy. Results for the diamagnetic shift were compared with experimental results. 相似文献
110.
Cordula Grüttner Knut Müller Joachim Teller Fritz Westphal Allan Foreman Robert Ivkov 《Journal of magnetism and magnetic materials》2007
Bionized nanoferrite (BNF) particles with high specific power absorption rates were synthesized in the size range of 20–100 nm by high-pressure homogenization for targeted cancer therapy with alternating magnetic fields. Several strategies were used to conjugate antibodies to the BNF particles. These strategies were compared using an immunoassay to find optimal conditions to reach a high immunoreactivity of the final antibody–particle conjugate. 相似文献