全文获取类型
收费全文 | 28599篇 |
免费 | 4592篇 |
国内免费 | 3204篇 |
专业分类
化学 | 20632篇 |
晶体学 | 331篇 |
力学 | 1778篇 |
综合类 | 258篇 |
数学 | 3239篇 |
物理学 | 10157篇 |
出版年
2024年 | 19篇 |
2023年 | 509篇 |
2022年 | 560篇 |
2021年 | 828篇 |
2020年 | 1113篇 |
2019年 | 1053篇 |
2018年 | 881篇 |
2017年 | 844篇 |
2016年 | 1250篇 |
2015年 | 1265篇 |
2014年 | 1555篇 |
2013年 | 2134篇 |
2012年 | 2527篇 |
2011年 | 2709篇 |
2010年 | 1898篇 |
2009年 | 1675篇 |
2008年 | 1906篇 |
2007年 | 1680篇 |
2006年 | 1609篇 |
2005年 | 1423篇 |
2004年 | 1108篇 |
2003年 | 937篇 |
2002年 | 889篇 |
2001年 | 693篇 |
2000年 | 600篇 |
1999年 | 595篇 |
1998年 | 497篇 |
1997年 | 412篇 |
1996年 | 437篇 |
1995年 | 421篇 |
1994年 | 345篇 |
1993年 | 313篇 |
1992年 | 277篇 |
1991年 | 257篇 |
1990年 | 253篇 |
1989年 | 200篇 |
1988年 | 164篇 |
1987年 | 108篇 |
1986年 | 84篇 |
1985年 | 93篇 |
1984年 | 46篇 |
1983年 | 45篇 |
1982年 | 41篇 |
1981年 | 31篇 |
1980年 | 19篇 |
1979年 | 17篇 |
1978年 | 9篇 |
1977年 | 10篇 |
1974年 | 8篇 |
1973年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 20 毫秒
1.
2.
Journal of Visualization - The increasing availability of spatiotemporal data provides unprecedented opportunities for understanding the structure of an urban area in terms of people’s... 相似文献
3.
We experimentally analyze the heat capacity and thermal expansion of reference solids in a wide temperature range from several Kelvin to melting temperature,and establish a universal double-linear relation between the experimental heat capacity Cp and thermal expansion β,which is different from the previous models.The universal behavior between heat capacity and thermal expansion is important to predict the thermodynamic parameters at constant pressure,and is helpful for understanding the nature of thermal properties in solids. 相似文献
4.
Journal of Algebraic Combinatorics - APR tilts for path algebra kQ can be realized as the mutation of the quiver Q in $${\mathbb Z}Q$$ with respect to the translation. In this paper, we show that... 相似文献
5.
We generalize the P(N)-graded Lie superalgebras of Martinez-Zelmanov. This generalization is not so restrictive but suffcient enough so that we are able to have a classification for this generalized P(N)-graded Lie superalgebras. Our result is that the generalized P(N)-graded Lie super-algebra L is centrally isogenous to a matrix Lie superalgebra coordinated by an associative superalgebra with a super-involution. Moreover, L is P(N)-graded if and only if the coordinate algebra R is commutative and the super-involution is trivial. This recovers Martinez-Zelmanov's theorem for type P(N). We also obtain a generalization of Kac's coordinatization via Tits-Kantor-Koecher construction. Actually, the motivation of this generalization comes from the Fermionic-Bosonic module construction. 相似文献
6.
本文首先对双层规划的一个特殊例子即道德风险模型中使用的一阶条件方法(FOA)做简要的梳理,然后提出一种更为一般的使FOA有效的原则与方法。新方法主要依赖于代理人对委托人设置的目标的最优反应映射是否存在不动点,这个性质不要求原问题与用一阶条件放松以后的问题之间的约束集等价,从而也不要求代理人的期望效用对行动具有全局凹性。在新方法下,可以用较为简单的方法证明FOA在以下两种情形之一有效,即如果分布函数是概率分布的凸组合或者分布函数来自某些特殊的指数族分布。 相似文献
7.
8.
Meccanica - The multi-link press mechanism is developing in the direction of high speed and high precision. However, the non-uniform wear of joint clearance seriously affects the output motion... 相似文献
9.
10.
Yaoli Wang Yan Liang Huixiang Sheng Jin Wang Junjie Wang Shunhao He Mengdan Guan Yaqi Chen Prof. Gang Lu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(2):e202103709
Surface plasmon can trigger or accelerate many photochemical reactions, especially useful in energy and environmental industries. Recently, molecular adsorption has proven effective in modulating plasmon-mediated photochemistry, however the realized chemical reactions are limited and the underlying mechanism is still unclear. Herein, by using in situ dark-field optical microscopy, the plasmon-mediated oxidative etching of silver nanoparticles (Ag NPs), a typical hot-hole-driven reaction, is monitored continuously and quantitatively. The presence of thiol or thiophenol molecules is found essential in the silver oxidation. In addition, the rate of silver oxidation is modulated by the choice of different thiol or thiophenol molecules. Compared with the molecules having electron donating groups, the ones having electron accepting groups accelerate the silver oxidation dramatically. The thiol/thiophenol modulation is attributed to the modulation of the charge separation between the Ag NPs and the adsorbed thiol or thiophenol molecules. This work demonstrates the great potential of molecular adsorption in modulating the plasmon-mediated photochemistry, which will pave a new way for developing highly efficient plasmonic photocatalysts. 相似文献