全文获取类型
收费全文 | 15057篇 |
免费 | 990篇 |
国内免费 | 1122篇 |
专业分类
化学 | 7410篇 |
晶体学 | 88篇 |
力学 | 1084篇 |
综合类 | 168篇 |
数学 | 3318篇 |
物理学 | 5101篇 |
出版年
2023年 | 137篇 |
2022年 | 234篇 |
2021年 | 385篇 |
2020年 | 368篇 |
2019年 | 346篇 |
2018年 | 303篇 |
2017年 | 386篇 |
2016年 | 436篇 |
2015年 | 392篇 |
2014年 | 553篇 |
2013年 | 949篇 |
2012年 | 585篇 |
2011年 | 616篇 |
2010年 | 526篇 |
2009年 | 855篇 |
2008年 | 919篇 |
2007年 | 971篇 |
2006年 | 851篇 |
2005年 | 630篇 |
2004年 | 563篇 |
2003年 | 555篇 |
2002年 | 575篇 |
2001年 | 513篇 |
2000年 | 459篇 |
1999年 | 393篇 |
1998年 | 399篇 |
1997年 | 258篇 |
1996年 | 206篇 |
1995年 | 186篇 |
1994年 | 171篇 |
1993年 | 172篇 |
1992年 | 252篇 |
1991年 | 129篇 |
1990年 | 103篇 |
1989年 | 82篇 |
1988年 | 98篇 |
1987年 | 98篇 |
1986年 | 78篇 |
1985年 | 83篇 |
1984年 | 86篇 |
1983年 | 55篇 |
1982年 | 106篇 |
1981年 | 169篇 |
1980年 | 182篇 |
1979年 | 179篇 |
1978年 | 167篇 |
1977年 | 101篇 |
1976年 | 108篇 |
1973年 | 76篇 |
1972年 | 37篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Anne Buschmann Ute Ziegler Martin H. Groschup 《Accreditation and quality assurance》2004,9(4-5):191-197
The accumulation of pathological prion protein is used as a diagnostic marker for transmissible spongiform encephalopathies. According to European Union (EU) regulations cattle older than 30 months of age (Germany, France, Italy, and Spain by national law >24 months) and slaughtered for human consumption must be tested by using rapid tests for bovine spongiform encephalopathy (BSE). Likewise fallen stock and clinically affected animals must be tested. This article gives a short overview of the incidence of BSE in Europe. The diagnostic hierarchy, i.e., the officially approved methodology for the confirmation of suspect rapid test cases, and the organization of the numerous laboratories involved in this large-scale testing for BSE are described. Special emphasis is given to necessary quality control measures currently in place for BSE rapid testing laboratories and to measures intended to assure a consistent performance of the commercially available rapid test kits.Presented at BERM-9—Ninth International Symposium on Biological and Environmental Reference Materials, 15–19 June 2003, Berlin, Germany. 相似文献
42.
43.
44.
45.
Lahcne Mezrag 《Mathematische Nachrichten》2004,266(1):60-67
In [5], it is proved that a bounded linear operator u, from a Banach space Y into an Lp(S, ν) factors through Lp1 (S, ν) for some p1 > 1, if Y* is of finite cotype; (S, ν) is a probability space for p = 0, and any measure space for 0 < p < 1. In this paper, we generalize this result to uv, where u : Y → Lp(S, ν) and v : X → Y are linear operators such that v* is of finite Ka?in cotype. This result gives also a new proof of Grothendieck's theorem. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
46.
A carousel is a dynamical system that describes the movement of an equilateral linkage in which the midpoint of each rod travels parallel to it. They are closely related to the floating body problem. We prove, using the work of Auerbach, that any figure that floats in equilibrium in every position is drawn by a carousel. Of special interest are such figures with rational perimetral density of the floating chords, which are then drawn by carousels. In particular, we prove that for some perimetral densities the only such figure is the circle, as the problem suggests. 相似文献
47.
M. A. Efendiev J. Fuhrmann S. V. Zelik 《Mathematical Methods in the Applied Sciences》2004,27(8):907-930
For the Boussinesq approximation of the equations of coupled heat and fluid flow in a porous medium we show that the corresponding system of partial differential equations possesses a global attractor. We give lower and upper bounds of the Hausdorff dimension of the attractor depending on a physical parameter of the system, namely the Rayleigh number of the flow. Numerical experiments confirm the theoretical findings and raise new questions on the structure of the solutions of the system. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
48.
内部审核在计量体系中的作用 总被引:1,自引:0,他引:1
介绍内部审核制度在计量测试工作中的目的和作用,提出了内部审核工作应注意的事项,如内部审核工作计划的完整性,内部审核工作的有效性,管理者工作内容的全面性,以及后续工作的完善性。 相似文献
49.
胡迪鹤 《数学物理学报(B辑英文版)》2005,25(1):23-29
This paper is a continuation of [8]. In Section 1, three kinds of communication are introdnced for two states and the relations among them are investigated. In Section 2, two kinds of period of a state are introdnced and it is obtained that the period is a “class property” ,i.e. two states x and y belong to same class implies the period of x is equal to the period of y. 相似文献
50.
In this paper, we evaluate various analytic Feynman integrals of first variation, conditional first variation, Fourier-Feynman
transform and conditional Fourier-Feynman transform of cylinder type functions defined over Wiener paths in abstract Wiener
space. We also derive the analytic Feynman integral of the conditional Fourier-Feynman transform for the product of the cylinder
type functions which define the functions in a Banach algebra introduced by Yoo, with n linear factors. 相似文献