全文获取类型
收费全文 | 86589篇 |
免费 | 683篇 |
国内免费 | 435篇 |
专业分类
化学 | 30088篇 |
晶体学 | 880篇 |
力学 | 6979篇 |
数学 | 32638篇 |
物理学 | 17122篇 |
出版年
2023年 | 54篇 |
2022年 | 190篇 |
2021年 | 226篇 |
2020年 | 178篇 |
2019年 | 173篇 |
2018年 | 10556篇 |
2017年 | 10351篇 |
2016年 | 6308篇 |
2015年 | 1099篇 |
2014年 | 633篇 |
2013年 | 888篇 |
2012年 | 4468篇 |
2011年 | 11220篇 |
2010年 | 6054篇 |
2009年 | 6387篇 |
2008年 | 7154篇 |
2007年 | 9282篇 |
2006年 | 708篇 |
2005年 | 1753篇 |
2004年 | 1909篇 |
2003年 | 2277篇 |
2002年 | 1319篇 |
2001年 | 454篇 |
2000年 | 460篇 |
1999年 | 277篇 |
1998年 | 257篇 |
1997年 | 220篇 |
1996年 | 288篇 |
1995年 | 194篇 |
1994年 | 149篇 |
1993年 | 149篇 |
1992年 | 112篇 |
1991年 | 109篇 |
1990年 | 100篇 |
1989年 | 92篇 |
1988年 | 84篇 |
1987年 | 69篇 |
1986年 | 67篇 |
1985年 | 72篇 |
1984年 | 60篇 |
1983年 | 53篇 |
1982年 | 59篇 |
1981年 | 54篇 |
1980年 | 58篇 |
1979年 | 57篇 |
1978年 | 50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 0 毫秒
151.
152.
153.
The periodic precipitation pattern formation in gelatinous media is interpreted as a moving boundary problem. The time law,
spacing law and width law are revisited on the basis of the new scenario. The explicit dependence of the geometric structure
on the initial concentrations of the reactants is derived. Matalon—Packter law, which relates the spacing coefficient with
the initial concentrations is reformulated removing many ambiguities and impractical parameters. Experimental results are
discussed to establish the significance of moving boundary concept in the diffusion controlled pattern forming systems 相似文献
154.
The rate-dependent effects in metallic ferromagnetic materials with magnetization processes attributed to domain-walls motion were studied. The experimental method for eddy-current relaxation time determination was proposed. Some discrepancies between the data and theoretical predictions were observed and discussed. The origin of these discrepancies is accounted for by the decrease of viscous-type relaxation process as the rate of change of averaged magnetization is approaching zero. 相似文献
155.
156.
The Nambu-bracket quantization of the hydrogen atom is worked out as an illustration of the general method. The dynamics of topological open branes is controlled classically by Nambu brackets. Such branes then may be quantized through the consistent quantization of the underlying Nambu brackets: properly defined, the quantum Nambu-brackets comprise an associative structure, although the naive derivation property is mooted through operator entwinement. For superintegrable systems, such as the hydrogen atom, the results coincide with those furnished by Hamiltonian quantization - but the method is not limited to Hamiltonian systems. 相似文献
157.
林诒勋 《高校应用数学学报(英文版)》2003,18(3):361-369
§ 1 IntroductionThe cutwidth problem for graphs,as well as a class of optimal labeling and embed-ding problems,have significant applications in VLSI designs,network communicationsand other areas (see [2 ] ) .We shall follow the graph-theoretic terminology and notation of [1 ] .Let G=(V,E)be a simple graph with vertex set V,| V| =n,and edge set E.A labeling of G is a bijec-tion f:V→ { 1 ,2 ,...,n} ,which can by regarded as an embedding of G into a path Pn.Fora given labeling f of G,th… 相似文献
158.
In this paper a tripartite qualitative design combining abservation, stimulated recall and interview is presented and discussed. This three-step-design makes it possible to get insight into the interaction of internal and external processes when solving mathematical tasks. The data analysis depends on the research question and the methodological approach. In the light of two research projects in mathematics education two different methods of data analysis are presented and methodologically reflected. 相似文献
159.
Jin-Mok Hur Chung-Seok Seo Sun-Seok Hong Dae-Seung Kang Seong-Won Park 《Reaction Kinetics and Catalysis Letters》2003,80(2):217-222
The concept of a novel electrochemical reduction process for the treatment of spent nuclear fuels in Li2O-LiCl molten salt was proposed and fresh tests using U3O8 powder were carried out to elucidate the reaction mechanism and verify the feasibility of the process. Electrolysis of Li2O and reduction of U3O8 powder took place simultaneously at the cathode part of the electrolysis cell via a catalytic EC mechanism and the conversion of U3O8 to U metal was more than 99%.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
160.