全文获取类型
收费全文 | 20180篇 |
免费 | 1623篇 |
国内免费 | 1676篇 |
专业分类
化学 | 4934篇 |
晶体学 | 273篇 |
力学 | 1964篇 |
综合类 | 270篇 |
数学 | 11395篇 |
物理学 | 4643篇 |
出版年
2024年 | 33篇 |
2023年 | 155篇 |
2022年 | 247篇 |
2021年 | 308篇 |
2020年 | 407篇 |
2019年 | 373篇 |
2018年 | 370篇 |
2017年 | 441篇 |
2016年 | 466篇 |
2015年 | 369篇 |
2014年 | 676篇 |
2013年 | 1327篇 |
2012年 | 911篇 |
2011年 | 1215篇 |
2010年 | 1124篇 |
2009年 | 1525篇 |
2008年 | 1563篇 |
2007年 | 1525篇 |
2006年 | 1359篇 |
2005年 | 1116篇 |
2004年 | 961篇 |
2003年 | 938篇 |
2002年 | 898篇 |
2001年 | 705篇 |
2000年 | 658篇 |
1999年 | 575篇 |
1998年 | 493篇 |
1997年 | 373篇 |
1996年 | 360篇 |
1995年 | 291篇 |
1994年 | 267篇 |
1993年 | 175篇 |
1992年 | 186篇 |
1991年 | 148篇 |
1990年 | 115篇 |
1989年 | 90篇 |
1988年 | 88篇 |
1987年 | 72篇 |
1986年 | 74篇 |
1985年 | 78篇 |
1984年 | 65篇 |
1983年 | 34篇 |
1982年 | 67篇 |
1981年 | 60篇 |
1980年 | 48篇 |
1979年 | 38篇 |
1978年 | 27篇 |
1977年 | 19篇 |
1976年 | 19篇 |
1973年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 957 毫秒
161.
By using the theory of coincidence degree, we study a kind of periodic solutions to p-Laplacian neutral functional differential equation with multiple deviating arguments, a new result on the existence of periodic solutions is obtained. 相似文献
162.
Qin Jiang 《Journal of Mathematical Analysis and Applications》2007,328(1):380-389
Some solvability conditions of periodic and subharmonic solutions are obtained for a class of subquadratic nonautonomous second-order Hamiltonian systems by the minimax methods in critical point theory. 相似文献
163.
Jesús de la Cal Javier Cárcamo 《Journal of Mathematical Analysis and Applications》2007,334(2):1106-1115
As a consequence of Jensen's inequality, centered operators of probabilistic type (also called Bernstein-type operators) approximate convex functions from above. Starting from this fact, we consider several pairs of classical operators and determine, in each case, which one is better to approximate convex functions. In almost all the discussed examples, the conclusion follows from a simple argument concerning composition of operators. However, when comparing Szász-Mirakyan operators with Bernstein operators over the positive semi-axis, the result is derived from the convex ordering of the involved probability distributions. Analogous results for non-centered operators are also considered. 相似文献
164.
An energy-dependent partitioning scheme is explored for extracting a small number of eigenvalues of a real symmetric matrix with the help of genetic algorithm. The proposed method is tested with matrices of different sizes (30 × 30 to 1000 × 1000). Comparison is made with Löwdin’s strategy for solving the problem. The relative advantages and disadvantages of the GA-based method are analyzed 相似文献
165.
Gui-xiang Xu Institute of Applied Physics Computational Mathematics P.O.Box Beijing China 《应用数学学报(英文版)》2007,(4)
In this paper,we consider the local and global solution for the nonlinear Schrdinger equationwith data in the homogeneous and nonhomogeneous Besov space and the scattering result for small data.Thetechniques to be used are adapted from the Strichartz type estimate,Kato's smoothing effect and the maximalfunction(in time)estimate for the free Schrdinger operator. 相似文献
166.
G. K. Shenoy 《Hyperfine Interactions》2006,170(1-3):5-13
Stanley L. Ruby (1924–2004) made major contributions to Mössbauer spectroscopy and was the first to suggest the feasibility of observing the Mössbauer effect using synchrotron radiation. In this article we recall his scientific legacy that have inspired his scientific colleagues. 相似文献
167.
Fe–Al alloys around the concentration of 30 at. % Al present re-entrant spin-glass behaviour at low temperatures. This behaviour is not completely understood and Mössbauer spectroscopy, combined with other experimental techniques, is useful to describe and explain this behaviour. Results show that the Mössbauer spectra coincide with the magnetic behaviour showed in literature and they can be explained as a magnetic cluster system whose magnetic clusters are getting smaller when the temperature is decreasing. When the temperature is reaching to the spin-glass transition at 92 K the spins in the paramagnetic matrix are moving slower and below this transition the spins are completely frozen. 相似文献
168.
169.
Bifurcations of Invariant Tori and Subharmonic Solutions of Singularly Perturbed System 总被引:1,自引:1,他引:0
下载免费PDF全文
![点击此处可从《数学年刊B辑(英文版)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
This paper deals with bifurcations of subharmonic solutions and invariant tori generated from limit cycles in the fast dynamics for a nonautonomous singularly perturbed system. Based on Poincare map, a series of blow-up transformations and the theory of integral manifold, the conditions for the existence of invariant tori are obtained, and the saddle-node bifurcations of subharmonic solutions are studied. 相似文献
170.
用Langer变换和Olver变换求得一类具有转向点问题的n阶近似解:y(x)=v(x)ψ(x),其中ψ=λ12-14×(x2-1)14,2332=-λx∫11-τ2dτ,v(z)=A(z,λ)ξ(λ23z)+B(z,λ)'ζ(λ23z).并探讨了其特征值问题,得到λn=4n+1112,n=0,1,2….由此给出了该类问题的解的一般性结论. 相似文献