全文获取类型
收费全文 | 2799篇 |
免费 | 128篇 |
国内免费 | 248篇 |
专业分类
化学 | 213篇 |
晶体学 | 1篇 |
力学 | 50篇 |
综合类 | 30篇 |
数学 | 2657篇 |
物理学 | 224篇 |
出版年
2024年 | 2篇 |
2023年 | 21篇 |
2022年 | 35篇 |
2021年 | 30篇 |
2020年 | 41篇 |
2019年 | 61篇 |
2018年 | 57篇 |
2017年 | 53篇 |
2016年 | 67篇 |
2015年 | 58篇 |
2014年 | 125篇 |
2013年 | 182篇 |
2012年 | 108篇 |
2011年 | 149篇 |
2010年 | 124篇 |
2009年 | 201篇 |
2008年 | 227篇 |
2007年 | 177篇 |
2006年 | 161篇 |
2005年 | 151篇 |
2004年 | 108篇 |
2003年 | 112篇 |
2002年 | 105篇 |
2001年 | 96篇 |
2000年 | 84篇 |
1999年 | 88篇 |
1998年 | 86篇 |
1997年 | 73篇 |
1996年 | 59篇 |
1995年 | 36篇 |
1994年 | 32篇 |
1993年 | 28篇 |
1992年 | 26篇 |
1991年 | 16篇 |
1990年 | 16篇 |
1989年 | 16篇 |
1988年 | 15篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 27篇 |
1984年 | 18篇 |
1983年 | 5篇 |
1982年 | 15篇 |
1981年 | 15篇 |
1980年 | 19篇 |
1979年 | 15篇 |
1978年 | 9篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1969年 | 2篇 |
排序方式: 共有3175条查询结果,搜索用时 31 毫秒
81.
We show in the smooth category that the heat trace asymptotics and the heat content asymptotics can be made to grow arbitrarily rapidly. In the real analytic context, however, this is not true and we establish universal bounds on their growth. 相似文献
82.
Szymon G?a?b 《Topology and its Applications》2011,158(1):93-100
An ideal J of subsets of a Polish space X has (LK) property whenever for every sequence (An) of analytic sets in X, if lim supn∈HAn∉J for each infinite H then ?n∈G∉J for some infinite G. In this note we present a new class of σ-ideals with (LK) property. 相似文献
83.
In this paper we study spectral sets which are unions of finitely many intervals in R. We show that any spectrum associated with such a spectral set Ω is periodic, with the period an integral multiple of the measure of Ω. As a consequence we get a structure theorem for such spectral sets and observe that the generic case is that of the equal interval case. 相似文献
84.
We investigate certain geometric properties of the spaces of idempotent measures. In particular, we prove that the space of idempotent measures on an infinite compact metric space is homeomorphic to the Hilbert cube. 相似文献
85.
86.
Iran Sheikhshoaie Helen Stoeckli-Evans Alireza Akbari S. Ali Yasrebi S. Yousef Ebrahimipour 《Arabian Journal of Chemistry》2012,5(2):173-178
The crystal and molecular structure of methanol {E-N′-(2-hydroxybenzlidene)benzohydrazido}dioxidomolybdenum (VI) was determined by single crystal X-ray diffraction. B3LYP/DZP basis set theoretical calculations nicely reproduce the X-ray experimental geometry. The obtained results are discussed in connection with the electronic and structural properties of the compound. 相似文献
87.
《复变函数与椭圆型方程》2012,57(15):1163-1164
Let X be a smooth and connected Riemann surface of genus g 0 and f: X P1, h: X P1 non-constant meromorphic functions on X. Fix an integer n 4 and assume the existence of n distinct points a1, , an P1 such that [image omitted] (set-theoretically) for every i. Here we prove that either f = h or [image omitted]. 相似文献
88.
Alessandro Antonucci Yi Sun Marco Zaffalon 《International Journal of Approximate Reasoning》2010,51(5):474-484
Credal networks generalize Bayesian networks by relaxing the requirement of precision of probabilities. Credal networks are considerably more expressive than Bayesian networks, but this makes belief updating NP-hard even on polytrees. We develop a new efficient algorithm for approximate belief updating in credal networks. The algorithm is based on an important representation result we prove for general credal networks: that any credal network can be equivalently reformulated as a credal network with binary variables; moreover, the transformation, which is considerably more complex than in the Bayesian case, can be implemented in polynomial time. The equivalent binary credal network is then updated by L2U, a loopy approximate algorithm for binary credal networks. Overall, we generalize L2U to non-binary credal networks, obtaining a scalable algorithm for the general case, which is approximate only because of its loopy nature. The accuracy of the inferences with respect to other state-of-the-art algorithms is evaluated by extensive numerical tests. 相似文献
89.
We construct faithful actions of quantum permutation groups on connected compact metrizable spaces. This disproves a conjecture of Goswami. 相似文献
90.