全文获取类型
收费全文 | 9280篇 |
免费 | 937篇 |
国内免费 | 609篇 |
专业分类
化学 | 2223篇 |
晶体学 | 58篇 |
力学 | 1043篇 |
综合类 | 111篇 |
数学 | 4775篇 |
物理学 | 2616篇 |
出版年
2024年 | 14篇 |
2023年 | 97篇 |
2022年 | 117篇 |
2021年 | 180篇 |
2020年 | 249篇 |
2019年 | 262篇 |
2018年 | 239篇 |
2017年 | 261篇 |
2016年 | 289篇 |
2015年 | 223篇 |
2014年 | 355篇 |
2013年 | 830篇 |
2012年 | 382篇 |
2011年 | 438篇 |
2010年 | 394篇 |
2009年 | 487篇 |
2008年 | 533篇 |
2007年 | 606篇 |
2006年 | 509篇 |
2005年 | 448篇 |
2004年 | 458篇 |
2003年 | 434篇 |
2002年 | 372篇 |
2001年 | 332篇 |
2000年 | 317篇 |
1999年 | 293篇 |
1998年 | 240篇 |
1997年 | 264篇 |
1996年 | 167篇 |
1995年 | 140篇 |
1994年 | 123篇 |
1993年 | 111篇 |
1992年 | 94篇 |
1991年 | 98篇 |
1990年 | 54篇 |
1989年 | 35篇 |
1988年 | 40篇 |
1987年 | 47篇 |
1986年 | 38篇 |
1985年 | 50篇 |
1984年 | 35篇 |
1983年 | 24篇 |
1982年 | 32篇 |
1981年 | 20篇 |
1980年 | 19篇 |
1979年 | 18篇 |
1978年 | 12篇 |
1977年 | 13篇 |
1976年 | 11篇 |
1973年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
J. Teixeira 《Il Nuovo Cimento D》1994,16(9):1433-1437
Summary The dynamics of water molecules occupying very small volumes can be probed by incoherent quasi-elastic neutron scattering.
We summarise some results obtained with wet samples of porous silica and hydrated proteins. The movements of the molecules
in the vicinity of the substrate are extremely reduced as compared to those of bulk water at the same temperature. Almost
only rotational movements subsist and the local diffusion is of the order of that observed in deeply supercooled water.
Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4–8, 1994. 相似文献
72.
具有非局部边界条件的奇摄动反应扩散问题 总被引:2,自引:0,他引:2
本文研究了一类具有非局部边界条件的奇摄动反应扩散初始边值问题.在适当的条件下,利用比较定理讨论了问题解的渐近性态. 相似文献
73.
V. A. Morozov E. M. Mukhamadiev A. B. Nazimov 《Computational Mathematics and Mathematical Physics》2007,47(12):1885-1892
Regularization of singular systems of linear algebraic equations by shifts is examined. New equivalent conditions for the shift regularizability of such systems are derived. 相似文献
74.
A. V. Kravtsov 《Computational Mathematics and Mathematical Physics》2007,47(11):1875-1884
A linear problem of parametric oscillations of a low-viscous two-layer fluid in a closed vessel partially filled with a porous medium is studied. An asymptotic solution is constructed on the basis of combined application of boundary functions and averaging methods. Approximate formulas for boundaries of instability domains in the case of subharmonic and harmonic resonances are derived. 相似文献
75.
Wing-Sum Cheung Patricia J.Y. Wong 《Journal of Mathematical Analysis and Applications》2007,329(2):851-869
We consider a system of focal boundary value problems where the nonlinearities may be singular in the independent variable and may also be singular in the dependent arguments. Using Schauder fixed point theorem, we establish criteria such that the system of boundary value problems has at least one fixed-sign solution. 相似文献
76.
《中国科学A辑(英文版)》2007,(7)
The double loop network(DLN)is a circulant digraph with n nodes and outdegree 2.It is an important topological structure of computer interconnection networks and has been widely used in the designing of local area networks and distributed systems.Given the number n of nodes,how to construct a DLN which has minimum diameter?This problem has attracted great attention.A related and longtime unsolved problem is:for any given non-negative integer k,is there an infinite family of k-tight optimal DLN?In this paper,two main results are obtained:(1)for any k≥0,the infinite families of k-tight optimal DLN can be constructed,where the number n(k,e,c)of their nodes is a polynomial of degree 2 in e with integral coefficients containing a parameter c.(2)for any k≥0, an infinite family of singular k-tight optimal DLN can be constructed. 相似文献
77.
This paper deals with a model of time-dependent double diffusive convection in Darcy flow. In particular it is concerned with the spatial decay of solutions when the flow is confined to a semi-infinite cylinder. Decay bounds for an energy expression are derived. 相似文献
78.
79.
We consider systems of two pure one-dimensional diffusion equations that have considerable interest in Soil Science and Mathematical Biology. We construct non-local symmetries for these systems. These are determined by expressing the equations in a partially and wholly conserved form, and then by performing a potential symmetry analysis on those systems that can be linearised. We give several examples of such systems, and in a specific case we show how linearising and hodograph-type mappings can lead to new solutions of the diffusion system. 相似文献
80.
In this paper, we prove Lp-boundedness of hyperbolic singular integral operators for kernels satisfying weakened regularity conditions, where 1
相似文献