全文获取类型
收费全文 | 26039篇 |
免费 | 2863篇 |
国内免费 | 5156篇 |
专业分类
化学 | 20221篇 |
晶体学 | 567篇 |
力学 | 1166篇 |
综合类 | 648篇 |
数学 | 3874篇 |
物理学 | 7582篇 |
出版年
2023年 | 194篇 |
2022年 | 453篇 |
2021年 | 749篇 |
2020年 | 588篇 |
2019年 | 642篇 |
2018年 | 511篇 |
2017年 | 725篇 |
2016年 | 900篇 |
2015年 | 1014篇 |
2014年 | 1151篇 |
2013年 | 2001篇 |
2012年 | 2049篇 |
2011年 | 2217篇 |
2010年 | 1678篇 |
2009年 | 1924篇 |
2008年 | 2058篇 |
2007年 | 1879篇 |
2006年 | 1746篇 |
2005年 | 1687篇 |
2004年 | 1715篇 |
2003年 | 1259篇 |
2002年 | 1188篇 |
2001年 | 829篇 |
2000年 | 785篇 |
1999年 | 494篇 |
1998年 | 364篇 |
1997年 | 291篇 |
1996年 | 303篇 |
1995年 | 264篇 |
1994年 | 215篇 |
1993年 | 239篇 |
1992年 | 216篇 |
1991年 | 130篇 |
1990年 | 146篇 |
1989年 | 135篇 |
1988年 | 132篇 |
1987年 | 117篇 |
1986年 | 107篇 |
1985年 | 124篇 |
1984年 | 120篇 |
1983年 | 94篇 |
1982年 | 82篇 |
1981年 | 83篇 |
1980年 | 66篇 |
1979年 | 43篇 |
1978年 | 38篇 |
1977年 | 42篇 |
1976年 | 29篇 |
1975年 | 25篇 |
1974年 | 28篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
比浊法测定酸性镀铜液中微量氯离子 总被引:1,自引:0,他引:1
以乙二醇为增溶剂,硝酸银作沉淀剂,采用氯化银比浊法,在不分离硫酸铜的条件下,直接测定酸性镀铜液中微量氯离子。测定波长为440 nm,线形范围为0~50μg/25 mL,其表观摩尔吸光系数ε=1.3×105,方法检出限为0.035μg/mL,该法用于测定酸性镀铜液中微量氯离子在不同水平的加标回收率为95.4%~104.5%。结果表明,该法准确,快速,简便,其它的常见离子无干扰。 相似文献
103.
核糖体失活蛋白(ribosome-inactivating proteins,RIPs)是一类广泛存在于高等植物中能抑制核糖体翻译功能的毒蛋白.本文就核糖体失活蛋白在抗病毒、抗真菌、抗昆虫、抗肿瘤及艾滋病等方面的研究进展及应用作一综述. 相似文献
104.
105.
Some curvature conditions about the geodesics emanating from a submanifold are obtained. These conditions are used to to study the topological and geometric properties of the ambient spaces which admit some minimal submanifolds. 相似文献
106.
107.
Luis Anchordoqui María Teresa Dova Thomas McCauley Stephen Reucroft 《Annals of Physics》2004,314(1):145-207
The properties of cosmic rays with energies above 106 GeV have to be deduced from the spacetime structure and particle content of the air showers which they initiate. In this review we summarize the phenomenology of these giant air showers. We describe the hadronic interaction models used to extrapolate results from collider data to ultra high energies, and discuss the prospects for insights into forward physics at the LHC. We also describe the main electromagnetic processes that govern the longitudinal shower evolution, as well as the lateral spread of particles. Armed with these two principal shower ingredients and motivation from the underlying physics, we provide an overview of some of the different methods proposed to distinguish primary species. The properties of neutrino interactions and the potential of forthcoming experiments to isolate deeply penetrating showers from baryonic cascades are also discussed. We finally venture into a terra incognita endowed with TeV-scale gravity and explore anomalous neutrino-induced showers. 相似文献
108.
109.
María G. Armentano Ricardo G. Durn 《Numerical Methods for Partial Differential Equations》2003,19(5):653-664
In this article we analyze the effect of mass‐lumping in the linear triangular finite element approximation of second‐order elliptic eigenvalue problems. We prove that the eigenvalue obtained by using mass‐lumping is always below the one obtained with exact integration. For singular eigenfunctions, as those arising in non convex polygons, we prove that the eigenvalue obtained with mass‐lumping is above the exact eigenvalue when the mesh size is small enough. So, we conclude that the use of mass‐lumping is convenient in the singular case. When the eigenfunction is smooth several numerical experiments suggest that the eigenvalue computed with mass‐lumping is below the exact one if the mesh is not too coarse. © 2003 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 19: 653–664, 2003 相似文献
110.
We show that the tensor product B-spline basis and the triangular Bernstein basis are in some sense best conditioned among all nonnegative bases for the spaces of tensor product splines and multivariate polynomials, respectively. We also introduce some new condition numbers which are analogs of component-wise condition numbers for linear systems introduced by Skeel. 相似文献