全文获取类型
收费全文 | 3008篇 |
免费 | 375篇 |
国内免费 | 146篇 |
专业分类
化学 | 797篇 |
晶体学 | 6篇 |
力学 | 995篇 |
综合类 | 14篇 |
数学 | 419篇 |
物理学 | 1298篇 |
出版年
2024年 | 4篇 |
2023年 | 16篇 |
2022年 | 49篇 |
2021年 | 42篇 |
2020年 | 55篇 |
2019年 | 67篇 |
2018年 | 64篇 |
2017年 | 71篇 |
2016年 | 69篇 |
2015年 | 64篇 |
2014年 | 117篇 |
2013年 | 228篇 |
2012年 | 126篇 |
2011年 | 173篇 |
2010年 | 154篇 |
2009年 | 214篇 |
2008年 | 223篇 |
2007年 | 236篇 |
2006年 | 197篇 |
2005年 | 166篇 |
2004年 | 151篇 |
2003年 | 145篇 |
2002年 | 118篇 |
2001年 | 90篇 |
2000年 | 70篇 |
1999年 | 61篇 |
1998年 | 65篇 |
1997年 | 74篇 |
1996年 | 69篇 |
1995年 | 45篇 |
1994年 | 50篇 |
1993年 | 41篇 |
1992年 | 44篇 |
1991年 | 27篇 |
1990年 | 24篇 |
1989年 | 16篇 |
1988年 | 23篇 |
1987年 | 21篇 |
1986年 | 10篇 |
1985年 | 13篇 |
1984年 | 13篇 |
1982年 | 11篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有3529条查询结果,搜索用时 0 毫秒
11.
Fluorescence of metal complexes of 8-hydroxyquinoline derivatives in aqueous micellar media 总被引:1,自引:0,他引:1
The fluorescence characteristics of 8-hydroxyquinoline derivative complexes of A1(III), Ga(III), In(III), Zn(II), and Be(II) in differently charged micellar media are reported. For most of the chelates studied, large increases are observed in micellar media compared with those obtained in hydroorganic solvents. However, some exceptions are observed, of which the low fluorescence of Zn(II) chelates in anionic sodium lauryl sulfate media is the most noticeable. 相似文献
12.
传统的波动方程波场重建基于完全弹性介质,不能获得满意的地震资料分辨率,本基于能描述大地吸收弹性介质中地震波传播的斯托克斯波动方程.提出了一种新的多尺度粘弹性波动方程波场重建的方法,根据地震波传播核函数的物理特性,研究了一种新的物理小波,提出了小波多尺度波场重建方法。达到对吸收信息的补偿,提高地震资料的分辨率。 相似文献
13.
R. Durrett 《Journal of Theoretical Probability》1992,5(1):127-152
In this paper we consider the Greenberg-Hastings and cyclic color models. These models exhibit (at least) three different types of behavior. Depending on the number of colors and the size of two parameters called the threshold and range, the Greenberg-Hastings model either dies out, or has equilibria that consist of debris or fire fronts. The phase diagram for the cyclic color models is more complicated. The main result of this paper, Theorem 1, proves that the debris phase exists for both systems. 相似文献
14.
We summarize some recent results related to fluctuation-induced kinetics of diffusion-controlled processes. We show that kinetic behavior can be drastically changed due to fluctuation effects, spatial correlations between particles, and anomalous transport properties. In addition, we show that correlation-induced kinetics in some systems can govern the temporal evolution over the entire time domain. 相似文献
15.
C. Aslangul M. Barthélémy N. Pottier D. Saint-James 《Journal of statistical physics》1991,65(3-4):695-713
The random walk of a particle on a directed Bethe lattice of constant coordinanceZ is examined in the case of random hopping rates. As a result, the higher the coordinance, the narrower the regions of anomalous drift and diffusion. The annealed and quenched mean square dispersions are calculated in all dynamical phases. In opposition to the one-dimensional (Z=2) case, the annealed and quenched mean quadratic dispersions are shown to be identical in all phases.We shall employ indifferently the expressions Bethe lattice or infinite Cayley tree to denote an infinite ramified lattice of constant coordinanceZ.(4, 5) 相似文献
16.
17.
Alexander?B.?Balakin Winfried?ZimdahlEmail author 《General Relativity and Gravitation》2005,37(10):1731-1751
The material tensor of linear response in electrodynamics is constructed out of products of two symmetric second rank tensor
fields which in the approximation of geometrical optics and for uniaxial symmetry reduce to “optical” metrics, describing
the phenomenon of birefringence. This representation is interpreted in the context of an underlying internal geometrical structure
according to which the symmetric tensor fields are vectorial elements of an associated two-dimensional space. 相似文献
18.
H. Pascal 《International Journal of Heat and Fluid Flow》1988,9(4):381-388
In this paper the conditions for the existence of self-similar solutions of the equations governing unsteady flows through a porous medium are presented and discussed. The first two sections deal with the case of non-Newtonian fluids of power-law behavior; the third section analyzes the case of non-Darcy gas flows. The boundary and initial conditions occuring currently in a large class of fluid mechanics problems, of practical interest in engineering, are considered. 相似文献
19.
刘慈群 《应用数学和力学(英文版)》1988,9(6):521-252
The transient spherical flow behavior of a slightly compressible non-Newtonian, power-law fluids in porous media is studied.
A nonlinear partial differential equation of parabolic type is derived. The diffusivity equation for spherical flow is a special
case of the new equation. We obtain analytical, asymptotic and approximate solutions by using the methods of Laplace transform
and weighted mass conservation. The structures of asymptotic and approximate solutions are similar, which enriches the theory
of one-dimensional flow of non-Newtonian fluids through porous media. 相似文献
20.
P. M. Adler 《Transport in Porous Media》1988,3(2):185-198
The transversal Stokes flow of a Newtonian fluid through random and Sierpinski carpets is numerically calculated and the transversal permeability derived. In random carpets derived from site percolation, the average macroscopic permeability varies as (-
c)3/2, close to the critical porosity
c. This exponent is found to be slightly different from the conductivity exponent. Results for Sierpinski carpets are presented up to the fourth generation. The Carman equation is not verified in these two model porous media. 相似文献