全文获取类型
收费全文 | 131734篇 |
免费 | 9325篇 |
国内免费 | 6022篇 |
专业分类
化学 | 62661篇 |
晶体学 | 1449篇 |
力学 | 9708篇 |
综合类 | 328篇 |
数学 | 37652篇 |
物理学 | 35283篇 |
出版年
2024年 | 185篇 |
2023年 | 1143篇 |
2022年 | 2169篇 |
2021年 | 2206篇 |
2020年 | 2333篇 |
2019年 | 2234篇 |
2018年 | 11877篇 |
2017年 | 11657篇 |
2016年 | 8536篇 |
2015年 | 3550篇 |
2014年 | 3522篇 |
2013年 | 4472篇 |
2012年 | 8745篇 |
2011年 | 15257篇 |
2010年 | 8921篇 |
2009年 | 9128篇 |
2008年 | 9971篇 |
2007年 | 11675篇 |
2006年 | 3070篇 |
2005年 | 3731篇 |
2004年 | 3356篇 |
2003年 | 3430篇 |
2002年 | 2372篇 |
2001年 | 1314篇 |
2000年 | 1253篇 |
1999年 | 1227篇 |
1998年 | 1075篇 |
1997年 | 976篇 |
1996年 | 1030篇 |
1995年 | 869篇 |
1994年 | 712篇 |
1993年 | 644篇 |
1992年 | 510篇 |
1991年 | 488篇 |
1990年 | 407篇 |
1989年 | 316篇 |
1988年 | 256篇 |
1987年 | 229篇 |
1986年 | 231篇 |
1985年 | 206篇 |
1984年 | 141篇 |
1983年 | 138篇 |
1982年 | 111篇 |
1981年 | 86篇 |
1980年 | 84篇 |
1979年 | 67篇 |
1978年 | 49篇 |
1977年 | 59篇 |
1976年 | 47篇 |
1973年 | 47篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
The Iyengar Type Inequalities with Exact Estimations and the Chebyshev Central Algorithms of Integrals 总被引:3,自引:0,他引:3
Xing Hua WANG Shi Jun YANG 《数学学报(英文版)》2005,21(6):1361-1376
In this paper, both low order and high order extensions of the Iyengar type inequality are obtained. Such extensions are the best possible in the same sense as that of the Iyengar inequality. hzrthermore, the Chebyshev central algorithms of integrals for some function classes and some related problems are also considered and investigated. 相似文献
142.
143.
Valery V. Kiselev 《Central European Journal of Physics》2004,2(3):523-534
We calculate the leptonic constant for the pseudoscalar ground state of the B
c
meson in the framework of a QCD-motivated potential model taking into account the two-loop anomalous dimension for the heavy
quark current in nonrelativistic QCD as matched with full QCD. 相似文献
144.
Gaston Casanova 《Advances in Applied Clifford Algebras》2004,14(2):249-252
We define analytic functions within Clifford Algebras CL, and study their trigonometric properties. We write the addition formulas when their arguments, A and B in CL, commute, this generalizes ordinary trigonometry. We examine in particular the case A2 = 1.
相似文献
145.
M. Lashkarizadeh Bami 《Semigroup Forum》2004,69(2):219-229
In the present paper it is shown that if S1 and S2 are two
Clifford topological semigroups satisfying certain conditions
and T is an isometric isomorphism of LUC(S1*) onto LUC(S2*), then T
maps S1 topologically isomorphically onto S2. Furthermore, T
maps M
l
n(S1) (M(S1), respectively) isometrically
isomorphically onto M
l
n(S2) (M(S2), respectively). Indeed,
we have obtained a generalization of a well-known result of
Ghahramani, Lau and Losert for locally compact groups to a more
general setting of Clifford topological semigroups. 相似文献
146.
147.
Jeong Ryeol Choi 《International Journal of Theoretical Physics》2004,43(4):947-958
We derived the WKB wave function for the general time-dependent quadratic Hamiltonian system using a unitary transformation method. We applied our research to sinusodially drived Caldirola–Kanai oscillator and confirmed that the time evolution of our approximated WKB wave function is similar to that of the exact one. This wave function can be used to analyze the interference between the probability amplitudes contributed by the area of overlap in phase space of quantum states. 相似文献
148.
149.
Andrew Barton 《The Journal of the Operational Research Society》1987,38(10):965-974
This paper describes some work carried out in the Scientific Research and Development Branch (SRDB) of the Home Office, intended to contribute to an overall aim of building up internal expertise in the field of expert systems. This was done by carrying out a number of pilot and demonstrator projects, two of which are described in some detail. The plan, which proved successful, was to build as far as possible on the relevant skills already possessed by an OR group in the branch. The lessons learned from these are summarized in the hope that they will be of use to other groups who wish to become involved in this important area. 相似文献
150.
Sven Walter 《Acta Analytica》2005,20(3):32-47
Frank Jackson and Philip Pettit have defended a non-reductive account of causal relevance known as the ‘program explanation
account’. Allegedly, irreducible mental properties can be causally relevant in virtue of figuring in non-redundant program explanations which convey information not conveyed by explanations in terms of the physical properties that actually do the ‘causal work’.
I argue that none of the possible ways to spell out the intuitively plausible idea of a program explanation serves its purpose,
viz., defends non-reductive physicalism against Jaegwon Kim’s Causal Exclusion Argument according to which non-reductive physicalism is committed to epiphenomenalism because irreducible mental properties are ‘screened
off’ from causal relevance by their physical realizers. Jackson and Pettit’s most promising explication of a program explanation
appeals to the idea of invariance of effect under variation of realization, but I show that invariance of effect under variation of realization is neither necessary nor sufficient for causal relevance. 相似文献