全文获取类型
收费全文 | 86525篇 |
免费 | 1813篇 |
国内免费 | 1345篇 |
专业分类
化学 | 30305篇 |
晶体学 | 858篇 |
力学 | 7226篇 |
综合类 | 45篇 |
数学 | 33014篇 |
物理学 | 18235篇 |
出版年
2023年 | 209篇 |
2022年 | 367篇 |
2021年 | 371篇 |
2020年 | 479篇 |
2019年 | 403篇 |
2018年 | 10707篇 |
2017年 | 10488篇 |
2016年 | 6433篇 |
2015年 | 1267篇 |
2014年 | 824篇 |
2013年 | 953篇 |
2012年 | 4534篇 |
2011年 | 11260篇 |
2010年 | 6138篇 |
2009年 | 6488篇 |
2008年 | 7041篇 |
2007年 | 9160篇 |
2006年 | 684篇 |
2005年 | 1656篇 |
2004年 | 1796篇 |
2003年 | 2191篇 |
2002年 | 1292篇 |
2001年 | 430篇 |
2000年 | 470篇 |
1999年 | 337篇 |
1998年 | 327篇 |
1997年 | 278篇 |
1996年 | 349篇 |
1995年 | 230篇 |
1994年 | 187篇 |
1993年 | 164篇 |
1992年 | 144篇 |
1991年 | 137篇 |
1990年 | 107篇 |
1989年 | 112篇 |
1988年 | 102篇 |
1987年 | 81篇 |
1986年 | 87篇 |
1985年 | 77篇 |
1984年 | 69篇 |
1983年 | 46篇 |
1982年 | 49篇 |
1981年 | 47篇 |
1980年 | 57篇 |
1979年 | 50篇 |
1914年 | 45篇 |
1913年 | 40篇 |
1912年 | 40篇 |
1909年 | 41篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 103 毫秒
1.
2.
We extend the matrix version of Cochran's statistical theorem to outer inverses of a matrix. As applications, we investigate the Wishartness and independence of matrix quadratic forms for Kronecker product covariance structures. 相似文献
3.
4.
5.
Howard Robinson 《Acta Analytica》2005,20(3):7-10
Nicholas Nathan tries to resist the current version of the causal argument for sense-data in two ways. First he suggests that,
on what he considers to be the correct re-construction of the argument, it equivocates on the sense of proximate cause. Second
he defends a form of disjunctivism, by claiming that there might be an extra mechanism involved in producing veridical hallucination,
that is not present in perception. I argue that Nathan’s reconstruction of the argument is not the appropriate one, and that,
properly interpreted, the argument does not equivocate on proximate cause. Furthermore, I claim that his postulation of a
modified mechanism for hallucinations is implausibly ad hoc. 相似文献
6.
The adsorption of human serum albumin onto hydroxyapatite-modified silver electrodes has been in situ investigated by utilizing the piezoelectric quartz crystal impedance technique. The changes of equivalent circuit parameters were used to interpret the adsorption process. A kinetic model of two consecutive steps was derived to describe the process and compared with a first-order kinetic model by using residual analysis. The experimental data of frequency shift fitted to the model and kinetics parameters, k1, k2, psi1, psi2 and qr, were obtained. All fitted results were in reasonable agreement with the corresponding experimental results. Two adsorption constants (7.19 kJ mol(-1) and 22.89 kJ mol(-1)) were calculated according to the Arrhenius formula. 相似文献
7.
8.
9.
A graph G is 3‐domination critical if its domination number γ is 3 and the addition of any edge decreases γ by 1. Let G be a 3‐connected 3‐domination critical graph of order n. In this paper, we show that there is a path of length at least n?2 between any two distinct vertices in G and the lower bound is sharp. © 2002 John Wiley & Sons, Inc. J Graph Theory 39: 76–85, 2002 相似文献
10.