全文获取类型
收费全文 | 33877篇 |
免费 | 2796篇 |
国内免费 | 1792篇 |
专业分类
化学 | 11374篇 |
晶体学 | 197篇 |
力学 | 8974篇 |
综合类 | 364篇 |
数学 | 6717篇 |
物理学 | 10839篇 |
出版年
2024年 | 50篇 |
2023年 | 324篇 |
2022年 | 759篇 |
2021年 | 798篇 |
2020年 | 841篇 |
2019年 | 748篇 |
2018年 | 749篇 |
2017年 | 865篇 |
2016年 | 974篇 |
2015年 | 916篇 |
2014年 | 1274篇 |
2013年 | 2255篇 |
2012年 | 1573篇 |
2011年 | 1802篇 |
2010年 | 1410篇 |
2009年 | 1917篇 |
2008年 | 1958篇 |
2007年 | 1992篇 |
2006年 | 1853篇 |
2005年 | 1408篇 |
2004年 | 1429篇 |
2003年 | 1297篇 |
2002年 | 1231篇 |
2001年 | 1019篇 |
2000年 | 957篇 |
1999年 | 872篇 |
1998年 | 821篇 |
1997年 | 666篇 |
1996年 | 575篇 |
1995年 | 511篇 |
1994年 | 458篇 |
1993年 | 438篇 |
1992年 | 491篇 |
1991年 | 331篇 |
1990年 | 285篇 |
1989年 | 231篇 |
1988年 | 207篇 |
1987年 | 191篇 |
1986年 | 169篇 |
1985年 | 166篇 |
1984年 | 165篇 |
1983年 | 90篇 |
1982年 | 177篇 |
1981年 | 209篇 |
1980年 | 200篇 |
1979年 | 196篇 |
1978年 | 182篇 |
1977年 | 103篇 |
1976年 | 118篇 |
1973年 | 80篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
用一个计算机控制的倒扭摆研究了快冷Fe71 Al2 9合金中的两个内耗峰 .在快冷的Fe71 Al2 9样品中分别在 180℃(P1 ) ,340℃ (P2 )和 5 10℃ (P3)出现了内耗峰 ,而在慢冷的Fe71 Al2 9样品中只发现了P3峰 .快冷样品中的P1 和P2峰在从 6 5 0℃冷却下来的测量过程中或在 35 0℃经过较长时间的时效后消失 ,其峰高随时效时间的增加而下降 ,直至消失 .P1 和P2 峰都有弛豫特征 ,它们的激活能分别为 :H1 =1.0 3± 0 .0 8eV(P1 峰 ) ;H2 =1.6 4± 0 .0 5eV(P2 峰 ) .P1 峰被认为是无序合金中Al原子在四面体点阵内的最近邻运动所引起 ,P2 峰则是无序合金中Al原子在四面体点阵内的次近邻运动所引起 相似文献
52.
53.
54.
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
55.
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
56.
The rotating flow in the presence of a magnetic field is a problem belonging to hydromagnetics and deserves to be more widely studied than it has been to date. In the non‐linear regime the literature is scarce. We develop the governing equations for the unsteady hydromagnetic rotating flow of a fourth‐order fluid past a porous plate. The steady flow is governed by a boundary value problem in which the order of differential equations is more than the number of available boundary conditions. It is shown that by augmenting the boundary conditions based on asymptotic structures at infinity it is possible to obtain numerical solutions of the nonlinear hydromagnetic equations. Effects of uniform suction or blowing past the porous plate, exerted magnetic field and rotation on the flow phenomena, especially on the boundary layer structure near the plate, are numerically analysed and discussed. The flow behaviours of the Newtonian fluid and second‐, third‐ and fourth‐order non‐Newtonian fluids are compared for the special flow problem, respectively. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
57.
The electromagnetic (EM) energy flow near single spheres is investigated by applying Mie theory. From the patterns of the energy flow, the absorption and the scattering of light can be understood in the microscopic point of view. In the absorption profiles of metallic particles, most absorbed energy is consumed on the surface of the particles, which indicates that the resonance of surface plasmon is different from that of the bulk plasmon. Two mechanisms to enhanced local EM field are also distinguished. One is the surface plasmon resonance, and another one is the intensified energy flow. 相似文献
58.
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
59.
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
60.
探讨了设计负动量压缩因子(αp<0)的正负电子对撞机储存环磁聚焦结构的可行性及方法.作为应用实例,说明了设计αp<0的τ–粲工厂磁聚焦结构的可能性. 相似文献