全文获取类型
收费全文 | 114389篇 |
免费 | 6917篇 |
国内免费 | 4741篇 |
专业分类
化学 | 49459篇 |
晶体学 | 1292篇 |
力学 | 9046篇 |
综合类 | 288篇 |
数学 | 36030篇 |
物理学 | 29932篇 |
出版年
2024年 | 144篇 |
2023年 | 788篇 |
2022年 | 1300篇 |
2021年 | 1347篇 |
2020年 | 1506篇 |
2019年 | 1428篇 |
2018年 | 11367篇 |
2017年 | 11125篇 |
2016年 | 7679篇 |
2015年 | 2602篇 |
2014年 | 2432篇 |
2013年 | 3006篇 |
2012年 | 6953篇 |
2011年 | 13718篇 |
2010年 | 7843篇 |
2009年 | 8191篇 |
2008年 | 8950篇 |
2007年 | 10803篇 |
2006年 | 2350篇 |
2005年 | 2942篇 |
2004年 | 2819篇 |
2003年 | 3056篇 |
2002年 | 2030篇 |
2001年 | 1084篇 |
2000年 | 1165篇 |
1999年 | 994篇 |
1998年 | 927篇 |
1997年 | 830篇 |
1996年 | 891篇 |
1995年 | 736篇 |
1994年 | 617篇 |
1993年 | 525篇 |
1992年 | 484篇 |
1991年 | 391篇 |
1990年 | 352篇 |
1989年 | 297篇 |
1988年 | 267篇 |
1987年 | 229篇 |
1986年 | 212篇 |
1985年 | 198篇 |
1984年 | 147篇 |
1983年 | 107篇 |
1982年 | 101篇 |
1981年 | 74篇 |
1980年 | 62篇 |
1979年 | 54篇 |
1914年 | 45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 15 毫秒
31.
Graham Smith 《The Journal of the Operational Research Society》1989,40(9):761-770
Courses which teach discrete-event simulation are based on many different simulation languages. The requirements for a language to support teaching simulation are discussed. In particular, it is recommended that such languages separate into distinct modules those aspects of simulation which are taught as separate topics. Implementation of the separation is discussed. The SEESIM language, developed as a teaching aid, is described, and examples of its use are given. Straightforward use of SEESIM can be learned quickly, yet the language provides facilities for a staged introduction to advanced concepts of simulation. 相似文献
32.
33.
A two-dimensional, nonlinear, compressible, diabatic, nonhydrostatic photochemical-dynamical gravity wave model has been advanced. The model includes diabetic process produced by photochemistry and the effect of gravity wave on atmospheric chemical species. In the horizontal direction, the pseudospectral method is used. The finite difference approximations are used in vertical direction z and time t. The FICE method is used to solve the model. The model results on small amplitude fluctuation are very close to those of linear theory, which demonstrates the correctness of the model.
相似文献34.
A pressure sensitive paint (PSP) measurement has been known as a pressure field measurement technique based on the oxygen quenching phenomenon of luminescence of specific luminophores. A PSP measurement was applied for pressure field measurement in a low-solidity circular cascade diffuser of a single-stage transonic centrifugal compressor with 5 in pressure ratio for HFC134a gas. The oxygen concentration was about 500 ppm. Ru (bath-phen) was adsorbed on a silica-gel thinlayer chromatography sheet, and the sheet was pasted onto the side-wall between the cascade vanes. A drastic change in luminescent intensity was recognized during a surge condition. Also the pressure variations based on luminescent intensity agreed well with the pressure fluctuations measured using a semiconductor pressure sensor with high-frequency-response. It was shown that a PSP measurement worked well to investigate the unsteady pressure fields in a circular cascade diffuser of a transonic centrifugal compressor. Moreover, the time response of PSP becomes clear as a problem to be overcome for the present. 相似文献
35.
科学与完美是不是一致的?科学家们是否有权使用完美这个词?至少,对于物理学家和数学家来说答案是肯定的“是”.2002年,温伯格(Steven Weinberg)写道:“近代物理学的一些重要方程式是科学知识的永久部分,甚至比它们较早出现的美丽大教堂还要经久不衰.”1960年代,狄拉克(Paul A.M.Dirac)有句名言:“完整的方程式之完美较之它们适合实验结果更为重要.”1965年诺贝尔物理学奖获得者费因曼(Richard P.Feynman)也坚信他提出的一项理论,即使该理论显得与实验数据有矛盾.1957年,他写道:“理论是优雅和完美的,重大事件是短暂的闪光.” 相似文献
36.
37.
In this paper, the dimension of the spaces of bivariate spline with degree less that 2r and smoothness order r on the Morgan-Scott triangulation is considered. The concept of the instability degree in the dimension of spaces of bivariate spline is presented. The results in the paper make us conjecture the instability degree in the dimension of spaces of bivariate spline is infinity. 相似文献
38.
39.
Yasuyuki Kawahigashi 《Communications in Mathematical Physics》2002,226(2):269-287
We study the recent construction of subfactors by Rehren which generalizes the Longo–Rehren subfactors. We prove that if
we apply this construction to a non-degenerately braided subfactor N⊂M and α±-induction, then the resulting subfactor is dual to the Longo–Rehren subfactor M⊗M
opp⊂R arising from the entire system of irreducible endomorphisms of M resulting from αplusmn;-induction. As a corollary, we solve a problem on existence of braiding raised by Rehren negatively. Furthermore, we generalize
our previous study with Longo and Müger on multi-interval subfactors arising from a completely rational conformal net of factors
on S
1 to a net of subfactors and show that the (generalized) Longo–Rehren subfactors and α-induction naturally appear in this context.
Received: 11 September 2001 / Accepted: 7 October 2001 相似文献
40.
Julio Castellanos 《Mathematische Zeitschrift》2002,239(4):777-802
We consider complete ideals supported on finite sequences of infinitely near points, in regular local rings with dimensions
greater than two. We study properties of factorizations in Lipman special *-simple complete ideals. We relate it to a type
of proximity, linear proximity, of the points, and give conditions in order to have unique factorization. Several examples
are presented.
Received: 2 February 2000 / in final form: 14 March 2001 / Published online: 18 January 2002 相似文献