全文获取类型
收费全文 | 102772篇 |
免费 | 4275篇 |
国内免费 | 4122篇 |
专业分类
化学 | 41894篇 |
晶体学 | 1125篇 |
力学 | 8335篇 |
综合类 | 329篇 |
数学 | 35037篇 |
物理学 | 24449篇 |
出版年
2023年 | 326篇 |
2022年 | 451篇 |
2021年 | 660篇 |
2020年 | 815篇 |
2019年 | 847篇 |
2018年 | 11015篇 |
2017年 | 10843篇 |
2016年 | 7033篇 |
2015年 | 1945篇 |
2014年 | 1720篇 |
2013年 | 2204篇 |
2012年 | 5727篇 |
2011年 | 12594篇 |
2010年 | 7241篇 |
2009年 | 7728篇 |
2008年 | 8413篇 |
2007年 | 10416篇 |
2006年 | 1901篇 |
2005年 | 2795篇 |
2004年 | 2707篇 |
2003年 | 2913篇 |
2002年 | 2053篇 |
2001年 | 1068篇 |
2000年 | 991篇 |
1999年 | 760篇 |
1998年 | 708篇 |
1997年 | 551篇 |
1996年 | 580篇 |
1995年 | 424篇 |
1994年 | 396篇 |
1993年 | 314篇 |
1992年 | 259篇 |
1991年 | 239篇 |
1990年 | 222篇 |
1989年 | 181篇 |
1988年 | 169篇 |
1987年 | 163篇 |
1986年 | 153篇 |
1985年 | 135篇 |
1984年 | 97篇 |
1983年 | 75篇 |
1982年 | 78篇 |
1981年 | 66篇 |
1980年 | 74篇 |
1979年 | 64篇 |
1978年 | 62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 140 毫秒
71.
加肋圆柱壳在轴压作用下的屈曲和后屈曲 总被引:2,自引:2,他引:0
本文讨论完善和非完善的,纵向加肋和正交加肋圆柱壳在轴压作用下的屈曲和后屈曲性态.依据文[1]提供的圆柱薄壳屈曲的边界层理论及其分析方法,给出了加肋圆柱壳在轴压作用下的屈曲和后屈曲理论分析.本文同时讨论肋骨与壳板材料不同时对加肋圆柱壳屈曲和后屈曲性态的影响. 相似文献
72.
Xuechu Shen 《量子光学学报》2006,12(B08):55-56
The single and a few coupled quantum dots are important for future quantum information sciences and their investigation is also a big challenge in physics. We investigate here the electronic and exciton states and their interaction with each other via micro photoluminescence. The luminescence for single and a few dots as well as a dot molecule of CdSe/ZnSe are measured with very high resolution, under liquid He temperature and magnetic fields and with different polarization of excitation laser. The observed sharp spectral lines are attributed to the atomlike transitions of exciton, trion, biexciton… in the investigated single QD or QD molecule. Band filling, Zeeman splitting, spin transition and their relaxation are observed and investigated'from the spectra and compared with those of same material in different dimensions, and compared with the primary calculation as well. In addition, quite a few new phenomena, which can not be understood based on our present model and knowledge, are also observed; and some very interesting problems are left for further investigation. 相似文献
73.
带干扰的多险种风险模型 总被引:2,自引:0,他引:2
由于保险公司风险经营规模不断扩大,用单一险种的模型来描述风险过程存在局限性,本文讨论了带干扰多险种风险模型,应用鞅论方法,得出伦德伯格不等式和最终破产概率公式。 相似文献
74.
75.
76.
Dual fractional cutting plane algorithms, in which cutting planes are used to iteratively tighten a linear relaxation of an integer program,
are well-known and form the basis of the highly successful branch-and-cut method. It is rather less well-known that various primal cutting plane algorithms were developed in the 1960s, for example by Young. In a primal algorithm, the main role of the cutting
planes is to enable a feasible solution to the original problem to be improved. Research on these algorithms has been almost
non-existent.
In this paper we argue for a re-examination of these primal methods. We describe a new primal algorithm for pure 0-1 problems based on strong valid inequalities and give some encouraging computational results. Possible extensions to the case of general
mixed-integer programs are also discussed. 相似文献
77.
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
78.
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
79.
80.