全文获取类型
收费全文 | 168608篇 |
免费 | 7514篇 |
国内免费 | 10236篇 |
专业分类
化学 | 28125篇 |
晶体学 | 374篇 |
力学 | 7086篇 |
综合类 | 1327篇 |
数学 | 28124篇 |
物理学 | 24263篇 |
综合类 | 97059篇 |
出版年
2024年 | 251篇 |
2023年 | 1022篇 |
2022年 | 1813篇 |
2021年 | 2050篇 |
2020年 | 2187篇 |
2019年 | 2384篇 |
2018年 | 2056篇 |
2017年 | 2534篇 |
2016年 | 2788篇 |
2015年 | 3445篇 |
2014年 | 6177篇 |
2013年 | 7556篇 |
2012年 | 7692篇 |
2011年 | 8703篇 |
2010年 | 7424篇 |
2009年 | 9370篇 |
2008年 | 10015篇 |
2007年 | 11790篇 |
2006年 | 11242篇 |
2005年 | 10339篇 |
2004年 | 8849篇 |
2003年 | 8448篇 |
2002年 | 7395篇 |
2001年 | 6298篇 |
2000年 | 5672篇 |
1999年 | 4850篇 |
1998年 | 4142篇 |
1997年 | 3647篇 |
1996年 | 3334篇 |
1995年 | 3015篇 |
1994年 | 2866篇 |
1993年 | 2454篇 |
1992年 | 2326篇 |
1991年 | 2057篇 |
1990年 | 1810篇 |
1989年 | 1725篇 |
1988年 | 1457篇 |
1987年 | 933篇 |
1986年 | 644篇 |
1985年 | 514篇 |
1984年 | 465篇 |
1983年 | 218篇 |
1982年 | 359篇 |
1981年 | 410篇 |
1980年 | 306篇 |
1979年 | 299篇 |
1978年 | 225篇 |
1977年 | 209篇 |
1976年 | 157篇 |
1974年 | 112篇 |
排序方式: 共有10000条查询结果,搜索用时 7 毫秒
111.
Kasper K. Berthelsen Jesper Møller 《Bulletin of the Brazilian Mathematical Society》2002,33(3):351-367
This primer provides a self-contained exposition of the case where spatial birth-and-death processes are used for perfect
simulation of locally stable point processes. Particularly, a simple dominating coupling from the past (CFTP) algorithm and
the CFTP algorithms introduced in [13], [14], and [5] are studied. Some empirical results for the algorithms are discussed.
Received: 30 June 2002 相似文献
112.
A FUNDAMENTAL SOLUTION FOR THE LAPLACE OPERATOR ON THE QUATERNIONIC HEISENBERG GROUP 总被引:2,自引:0,他引:2
朱理 《数学物理学报(B辑英文版)》2002,22(3)
In this paper, the author studies the Laplace operator on the quaternionic Heisenberg group, construct a fundamental solution for it and use this solution to prove the Lp-boundedness and the weak (1-1) boundedness of certain singular convolution operators on the quaternionic Heisenberg group. 相似文献
113.
Taekyun Kim 《Journal of Mathematical Analysis and Applications》2002,273(1):236-242
The purpose of this paper is to give a proof of Kummer type congruence for the q-Bernoulli numbers of higher order, which is an answer to a part of the problem in a previous publication (see Indian J. Pure Appl. Math. 32 (2001) 1565-1570). 相似文献
114.
In this work we study nonnegativity and positivity of a discrete quadratic functional with separately varying endpoints. We introduce a notion of an interval coupled with 0, and hence, extend the notion of conjugate interval to 0 from the case of fixed to variable endpoint(s). We show that the nonnegativity of the discrete quadratic functional is equivalent to each of the following conditions: The nonexistence of intervals coupled with 0, the existence of a solution to Riccati matrix equation and its boundary conditions. Natural strengthening of each of these conditions yields a characterization of the positivity of the discrete quadratic functional. Since the quadratic functional under consideration could be a second variation of a discrete calculus of variations problem with varying endpoints, we apply our results to obtain necessary and sufficient optimality conditions for such problems. This paper generalizes our recent work in [R. Hilscher, V. Zeidan, Comput. Math. Appl., to appear], where the right endpoint is fixed. 相似文献
115.
不管是发达国家还是发展中国家,每个经济体的经济发展都要经历由传统农业社会向现代工业社会转型的经济发展过程,这是我们拓展发展经济学的理论视野。在发展经济学的分析框架中研究发达国家早期发展历程,并将其与当今发展中国家经济发展进行垮期比较研究的客观基础。这种跨期比较研究既能为发展经济学提供更丰富的经验素材,并从经济发展思想史中吸取思想营养,使其理论视野更为广阔、逻辑更为严谨,又能为当今发展中国家选择发展道路提供更为丰富具体的历史参照系和更深入的理论阐释。 相似文献
116.
117.
118.
Ludmila C. Fidale Sarah Köhler Martin H.G. Prechtl Thomas Heinze Omar A. El Seoud 《Cellulose (London, England)》2006,13(5):581-592
The concentrations of water, W, and electrolytes present in solutions of LiCl in N,N-dimethylacetamide, LiCl/DMAc, and of tetrabutylammonium fluoride. x-hydrate in DMSO, TBAF.xW/DMSO can be accurately and expediently determined by three independent methods, UV–vis, FTIR and EMF measurement. The first relies on the use of solvatochromic probes whose spectra are sensitive to solution composition. It is applicable to W/LiCl/DMAc solutions but not to TBAF.xW/DMSO, because the charge-transfer complex bands of the probes are suppressed by strong interactions with the latter electrolyte. Integration of νOH band of water may be employed in order to determine [W], hence [electrolyte] by weight difference. EMF measurement uses ion-selective electrodes in order to determine [electrolyte], hence [W] by weight difference. Results of the latter method were in excellent agreement with those of FTIR. The reason for the failure of Karl Fischer titration is addressed, and the relevance of the results obtained to functionalization of cellulose under homogenous solution conditions is briefly commented on. 相似文献
119.
不完全信息群体决策专家权重的集结 总被引:8,自引:5,他引:3
本文对于属性权重信息和属性效用信息都不完全的群体多属性决策问题,通过构造属性值区间和运用系统聚类分析法,对群体决策中的专家进行分类,并确定每位专家的权重. 相似文献
120.