全文获取类型
收费全文 | 59616篇 |
免费 | 3887篇 |
国内免费 | 7315篇 |
专业分类
化学 | 43667篇 |
晶体学 | 1273篇 |
力学 | 1101篇 |
综合类 | 456篇 |
数学 | 10928篇 |
物理学 | 13393篇 |
出版年
2024年 | 73篇 |
2023年 | 428篇 |
2022年 | 986篇 |
2021年 | 964篇 |
2020年 | 1281篇 |
2019年 | 1235篇 |
2018年 | 1097篇 |
2017年 | 1614篇 |
2016年 | 1689篇 |
2015年 | 1471篇 |
2014年 | 2032篇 |
2013年 | 4569篇 |
2012年 | 3908篇 |
2011年 | 3257篇 |
2010年 | 2733篇 |
2009年 | 3706篇 |
2008年 | 3851篇 |
2007年 | 3950篇 |
2006年 | 3620篇 |
2005年 | 3138篇 |
2004年 | 2938篇 |
2003年 | 2439篇 |
2002年 | 3351篇 |
2001年 | 2088篇 |
2000年 | 1890篇 |
1999年 | 1866篇 |
1998年 | 1542篇 |
1997年 | 1199篇 |
1996年 | 977篇 |
1995年 | 959篇 |
1994年 | 866篇 |
1993年 | 656篇 |
1992年 | 706篇 |
1991年 | 431篇 |
1990年 | 382篇 |
1989年 | 380篇 |
1988年 | 276篇 |
1987年 | 220篇 |
1986年 | 224篇 |
1985年 | 213篇 |
1984年 | 203篇 |
1983年 | 113篇 |
1982年 | 180篇 |
1981年 | 171篇 |
1980年 | 184篇 |
1979年 | 152篇 |
1978年 | 158篇 |
1977年 | 122篇 |
1976年 | 104篇 |
1974年 | 57篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
62.
S.-Y. Sheu D.-Y. Yang H.L. Selzle E.W. Schlag 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(3):557-563
Charge transport is one important example of signal transduction in a protein which is responsible for action at a distance,
and is a fundamental process in biochemical action. A model is presented in which electronic effects interact with motional
processes to combine into a bifunctional model. This model is investigated with new detailed molecular dynamics calculations
and successfully explains such action at a distance.
Received 1st February 2002 / Received in final form 26 May 2002 Published online 13 September 2002 相似文献
63.
meso-Tetra(n-hexyloxycarbonyl)porphyrin was found to be converted into porphine, the mother compound of porphyrins, in a 77% yield when heated in aqueous sulfuric acid at 180 °C over 30 min under an inert atmosphere. The observation demonstrates that the substituted porphyrin serves as a novel and useful precursor for porphine. 相似文献
64.
65.
We obtain upper bounds for the tail distribution of the first nonnegative sum of a random walk and for the moments of the overshoot over an arbitrary nonnegative level if the expectation of jumps is positive and close to zero. In addition, we find an estimate for the expectation of the first ladder epoch. 相似文献
66.
67.
68.
J. Kalliongis 《Mathematische Zeitschrift》2002,241(4):801-828
For compact irreducible sufficiently large 3-manifolds containing 2-sided projective planes, we consider the following Realization
Problem: Given a finite subgroup of the outer automorphism group of the fundamental group, is there a finite group of homeomorphisms,
which induces this subgroup?
Received: 16 November 1999; in final form: 18 January 2001 / Published online: 8 November 2002 相似文献
69.
Let G=(V(G),E(G)) be a graph. A (n,G, λ)‐GD is a partition of the edges of λKn into subgraphs (G‐blocks), each of which is isomorphic to G. The (n,G,λ)‐GD is named as graph design for G or G‐decomposition. The large set of (n,G,λ)‐GD is denoted by (n,G,λ)‐LGD. In this work, we obtain the existence spectrum of (n,P3,λ)‐LGD. © 2002 Wiley Periodicals, Inc. J Combin Designs 10: 151–159, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jcd.10008 相似文献
70.
P. Adamson 《Optics & Laser Technology》2002,34(7):561-568
The differential reflection characteristics for ultrathin inhomogeneous dielectric film on absorbing substrate are investigated in the long-wavelength approximation. The obtained first-order expressions for differential reflectivity and changes in the ellipsometric angles caused by ultrathin layer are of immediate interest to the solution of the inverse problem. The method to determine the averaged values (not the realistic profile) of refractive index for inhomogeneous nanometric films are shown. The novel possibilities for determining the dielectric constant and thickness of nanoscale homogeneous films by the differential ellipsometric and reflectivity measurements are developed, and a simple method to estimate whether the nanometric film is homogeneous or not is also discussed. 相似文献