全文获取类型
收费全文 | 4990篇 |
免费 | 720篇 |
国内免费 | 521篇 |
专业分类
化学 | 850篇 |
晶体学 | 35篇 |
力学 | 354篇 |
综合类 | 68篇 |
数学 | 2978篇 |
物理学 | 1946篇 |
出版年
2024年 | 12篇 |
2023年 | 68篇 |
2022年 | 94篇 |
2021年 | 125篇 |
2020年 | 159篇 |
2019年 | 175篇 |
2018年 | 177篇 |
2017年 | 197篇 |
2016年 | 206篇 |
2015年 | 148篇 |
2014年 | 262篇 |
2013年 | 508篇 |
2012年 | 238篇 |
2011年 | 217篇 |
2010年 | 229篇 |
2009年 | 261篇 |
2008年 | 317篇 |
2007年 | 309篇 |
2006年 | 277篇 |
2005年 | 279篇 |
2004年 | 233篇 |
2003年 | 229篇 |
2002年 | 223篇 |
2001年 | 167篇 |
2000年 | 162篇 |
1999年 | 161篇 |
1998年 | 138篇 |
1997年 | 115篇 |
1996年 | 99篇 |
1995年 | 84篇 |
1994年 | 68篇 |
1993年 | 40篇 |
1992年 | 40篇 |
1991年 | 24篇 |
1990年 | 25篇 |
1989年 | 29篇 |
1988年 | 21篇 |
1987年 | 12篇 |
1986年 | 13篇 |
1985年 | 15篇 |
1984年 | 16篇 |
1983年 | 5篇 |
1982年 | 13篇 |
1981年 | 11篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1978年 | 7篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 4篇 |
排序方式: 共有6231条查询结果,搜索用时 31 毫秒
11.
Harel and Puri (1989, J. Multivariate Anal. 29) studied the asymptotic behavior of the U-statistic and the one-sample rank order statistic for nonstationary absolutely regular processes. In this note, we present some applications of these results for Markov processes as well as ARMA processes. 相似文献
12.
13.
Modulo some natural generalizations to noncompact spaces, we show in this Letter that Moyal planes are nonunital spectral triples in the sense of Connes. The action functional of these triples is computed, and we obtain the expected result, i.e. the noncommutative Yang–Mills action associated with the Moyal product. In particular, we show that Moyal gauge theory naturally fits into the rigorous framework of noncommutative geometry. 相似文献
14.
M. Castagnino R. Id Betan R. Laura 《International Journal of Theoretical Physics》2003,42(10):2423-2439
By extending the notion of mixed states to functionals acting on the space of observables with diagonal singularity we obtain a well-defined complex spectral decomposition of the time evolution for a quantum decaying system. In this formalism, generalized Gamow states are obtained with well-defined physical properties. 相似文献
15.
This paper undertakes a systematic treatment of the low regularity local wellposedness and ill-posedness theory in Hs andHs for semilinear wave equations with polynomial nonlinearity in u and (e)u. This ill-posed result concerns the focusing type equations with nonlinearity on u and (e)tu. 相似文献
16.
Song LI Guo Mao WANG Zhi Song LIU 《数学学报(英文版)》2005,21(6):1475-1486
The purpose of this paper is to investigate the mean size formula of wavelet packets in Lp for 0 〈 p ≤ ∞. We generalize a mean size formula of wavelet packets given in terms of the p-norm joint spectral radius and we also give some asymptotic formulas for the Lp-norm or quasi-norm on the subdivision trees. All results will be given in the general setting, 相似文献
17.
Hubert Grudziński 《Reports on Mathematical Physics》2004,53(2):317-328
The eigenvalues and eigenfunctions of an elementary 3-fermion 2-body operator 3P2g∧I1A3∑1≤i≤j≤3P2g(i, j)A3 acting on a 3-particle antisymmetric finite-dimensional Hilbert space have been found. Here Pg2 denotes the projection operator onto a 2-particle antisymmetric function g2, while A3 denotes the 3-particle antisymmetrizing operator. 相似文献
18.
In this paper we continue to study the spectral norms and their completions ([4]) in the case of the algebraic closure $ \overline {\mathbb Q} $ of ? in ?. Let $ \widetilde{\overline{\mathbb{Q}}} $ be the completion of $ \overline {\mathbb Q} $ relative to the spectral norm. We prove that $ \widetilde{\overline{\mathbb{Q}}} $ can be identified with the R‐subalgebra of all symmetric functions of C(G), where C(G) denotes the ?‐Banach algebra of all continuous functions defined on the absolute Galois group G = Gal$ {\overline {\mathbb Q}} / {\mathbb Q} $. We prove that any compact, closed to conjugation subset of ? is the pseudo‐orbit of a suitable element of $ \widetilde{\overline{\mathbb{Q}}} $. We also prove that the topological closure of any algebraic number field in $ \widetilde{\overline{\mathbb{Q}}} $ is of the form $\widetilde{\mathbb{Q}[x]}$ with x in $ \widetilde{\overline{\mathbb{Q}}} $. 相似文献
19.
Based on the Fourier transform method, a simple closed-form expression for the on-axis power spectrum of ultrashort Gaussian pulsed beams in diffraction at a circular aperture is derived, which permits us to study spectral changes both analytically and numerically. It is shown that for diffracted pulsed beams there exist spectral red and blue shifts, spectral narrowing, and spectral switches in the near field. The aperture diffraction plays an important role in spectral switching, but both the truncation parameter and bandwidth (or equally, Fourier transform limited pulse duration) affect the behavior of spectral switches. 相似文献
20.
We characterize all equivariant odd spectral triples for the quantum SU(2) group acting on its L
2-space and having a nontrivial Chern character. It is shown that the dimension of an equivariant spectral triple is at least three, and given any element of the K-homology group of SUq(2), there is an equivariant odd spectral triple of dimension 3 inducing that element. The method employed to get equivariant spectral triples in the quantum case is then used for classical SU(2), and we prove that for p < 4, there does not exist any equivariant spectral triple with nontrivial K-homology class and dimension p acting on the L
2-space.The first author would like to acknowledge support from the National Board of Higher Mathematics, India. 相似文献