全文获取类型
收费全文 | 6177篇 |
免费 | 524篇 |
国内免费 | 823篇 |
专业分类
化学 | 235篇 |
晶体学 | 8篇 |
力学 | 217篇 |
综合类 | 89篇 |
数学 | 4821篇 |
物理学 | 2154篇 |
出版年
2024年 | 12篇 |
2023年 | 58篇 |
2022年 | 89篇 |
2021年 | 123篇 |
2020年 | 102篇 |
2019年 | 164篇 |
2018年 | 180篇 |
2017年 | 182篇 |
2016年 | 156篇 |
2015年 | 139篇 |
2014年 | 206篇 |
2013年 | 951篇 |
2012年 | 231篇 |
2011年 | 316篇 |
2010年 | 265篇 |
2009年 | 342篇 |
2008年 | 422篇 |
2007年 | 407篇 |
2006年 | 374篇 |
2005年 | 326篇 |
2004年 | 337篇 |
2003年 | 294篇 |
2002年 | 320篇 |
2001年 | 231篇 |
2000年 | 228篇 |
1999年 | 199篇 |
1998年 | 183篇 |
1997年 | 195篇 |
1996年 | 114篇 |
1995年 | 77篇 |
1994年 | 52篇 |
1993年 | 37篇 |
1992年 | 32篇 |
1991年 | 22篇 |
1990年 | 17篇 |
1989年 | 24篇 |
1988年 | 14篇 |
1987年 | 10篇 |
1986年 | 12篇 |
1985年 | 11篇 |
1984年 | 13篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 7篇 |
1976年 | 4篇 |
1975年 | 5篇 |
1973年 | 3篇 |
1936年 | 5篇 |
排序方式: 共有7524条查询结果,搜索用时 62 毫秒
1.
2.
3.
4.
《Current Applied Physics》2015,15(3):319-325
Pd is one of the metals suitable for inducing low-temperature crystallization in Ge. However, it is not clear how residual Pd atoms are integrated into the Ge lattice. Therefore, time-differential γ–γ perturbed angular correlations (TDPAC) technique using the 100Pd(→100Rh) nuclear probe produced by recoil implantation has been applied to study the hyperfine interactions of this probe in single-crystalline undoped Ge. A Pd-vacancy complex aligned along the <111> crystallographic direction with a unique interaction frequency of 8.4(5) Mrad/s has been identified. This complex was measured to have a maximum relative fraction of about 76(4)% following annealing at 350 °C. Further annealing at higher temperatures reduced this fraction, possibly via dissociation of the complex. Calculations suggest dissociation energy of 1.94(5) eV for the complex. DFT calculations performed in this work are in reasonable good agreement with the experimental values for the electric-field gradient of the defect complex in Ge and Si for comparison. The calculations predict a split-vacancy configuration with the Pd on a bond-centred interstitial site having a nearest-neighbour semi-vacancy on both sides (V-PdBI-V) in Ge and Si. 相似文献
5.
In this paper, the deformation of the Heisenberg algebra, consistent with both the generalized uncertainty principle and doubly special relativity, has been analyzed. It has been observed that, though this algebra can give rise to fractional derivative terms in the corresponding quantum mechanical Hamiltonian, a formal meaning can be given to them by using the theory of harmonic extensions of function. Depending on this argument, the expression of the propagator of the path integral corresponding to the deformed Heisenberg algebra, has been obtained. In particular, the consistent expression of the one dimensional free particle propagator has been evaluated explicitly. With this propagator in hand, it has been shown that, even in free particle case, normal generalized uncertainty principle and doubly special relativity show very much different result. 相似文献
6.
Summary This paper is concerned with the problem of developing numerical integration algorithms for differential equations that, when
viewed as equations in some Euclidean space, naturally evolve on some embedded submanifold. It is desired to construct algorithms
whose iterates also evolve on the same manifold. These algorithms can therefore be viewed as integrating ordinary differential
equations on manifolds. The basic method “decouples” the computation of flows on the submanifold from the numerical integration
process. It is shown that two classes of single-step and multistep algorithms can be posed and analyzed theoretically, using
the concept of “freezing” the coefficients of differential operators obtained from the defining vector field. Explicit third-order
algorithms are derived, with additional equations augmenting those of their classical counterparts, obtained from “obstructions”
defined by nonvanishing Lie brackets. 相似文献
7.
Algebra matrix and similarity classification of operators 总被引:1,自引:0,他引:1
ZHANG Zilong & LI Yucheng Department of Mathematics Hebei Normal University Shijiazhuang China 《中国科学A辑(英文版)》2006,49(3):398-409
In this paper, by the Gelfand representation theory and the Silov idempotents theorem, we first obtain a central decomposition theorem related to a unital semi-simple n-homogeneous Banach algebra, and then give a similarity classification of two strongly irreducible Cowen-Douglas operators using this theorem. 相似文献
8.
We give a coring version for the duality theorem for actions and coactions of a finitely generated projective Hopf algebra.
We also provide a coring analogue for a theorem of H.-J. Schneider, which generalizes and unifies the duality theorem for
finite Hopf algebras and its refinements.
This paper was written while the first author visited the Mathematics Departments of Syracuse University and California State
University Dominguez Hills. He would like to thank both departments for their hospitality. 相似文献
9.
The revival of the nondiffracting vortex beam after its interaction with the 2D on axis obstacle is examined. We show that the phase topology and the spatial distribution of the orbital angular momentum of the beam transmitted through the obstacle regenerate to the initial form during further free propagation. We verify that the healing effect appears even if the interaction is accompanied by the exchange of the orbital angular momentum. 相似文献
10.
We construct the complex simple Lie algebras using elementary algebraic geometry. We use our construction to obtain a new
proof of the classification of complex simple Lie algebras that does not appeal to the classification of root systems. 相似文献