全文获取类型
收费全文 | 20197篇 |
免费 | 2286篇 |
国内免费 | 2094篇 |
专业分类
化学 | 2152篇 |
晶体学 | 28篇 |
力学 | 1717篇 |
综合类 | 517篇 |
数学 | 14328篇 |
物理学 | 5835篇 |
出版年
2024年 | 17篇 |
2023年 | 165篇 |
2022年 | 248篇 |
2021年 | 344篇 |
2020年 | 410篇 |
2019年 | 431篇 |
2018年 | 446篇 |
2017年 | 574篇 |
2016年 | 657篇 |
2015年 | 504篇 |
2014年 | 1024篇 |
2013年 | 1328篇 |
2012年 | 1079篇 |
2011年 | 1276篇 |
2010年 | 1137篇 |
2009年 | 1406篇 |
2008年 | 1397篇 |
2007年 | 1488篇 |
2006年 | 1323篇 |
2005年 | 1258篇 |
2004年 | 1029篇 |
2003年 | 937篇 |
2002年 | 788篇 |
2001年 | 712篇 |
2000年 | 645篇 |
1999年 | 578篇 |
1998年 | 496篇 |
1997年 | 477篇 |
1996年 | 365篇 |
1995年 | 296篇 |
1994年 | 242篇 |
1993年 | 181篇 |
1992年 | 157篇 |
1991年 | 128篇 |
1990年 | 140篇 |
1989年 | 92篇 |
1988年 | 87篇 |
1987年 | 75篇 |
1986年 | 67篇 |
1985年 | 85篇 |
1984年 | 69篇 |
1983年 | 47篇 |
1982年 | 66篇 |
1981年 | 60篇 |
1980年 | 43篇 |
1979年 | 34篇 |
1978年 | 31篇 |
1977年 | 28篇 |
1976年 | 30篇 |
1973年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 343 毫秒
101.
《Mathematische Nachrichten》2017,290(1):37-49
We prove that Burenkov's extension operator preserves Sobolev spaces built on general Morrey spaces, including classical Morrey spaces. The analysis concerns bounded and unbounded open sets with Lipschitz boundaries in the n‐dimensional Euclidean space. 相似文献
102.
Rui Shen Zhiqing Meng Chuangyin Dang Min Jiang 《Numerical Functional Analysis & Optimization》2017,38(11):1473-1489
In this paper, an algorithm of barrier objective penalty function for inequality constrained optimization is studied and a conception–the stability of barrier objective penalty function is presented. It is proved that an approximate optimal solution may be obtained by solving a barrier objective penalty function for inequality constrained optimization problem when the barrier objective penalty function is stable. Under some conditions, the stability of barrier objective penalty function is proved for convex programming. Specially, the logarithmic barrier function of convex programming is stable. Based on the barrier objective penalty function, an algorithm is developed for finding an approximate optimal solution to an inequality constrained optimization problem and its convergence is also proved under some conditions. Finally, numerical experiments show that the barrier objective penalty function algorithm has better convergence than the classical barrier function algorithm. 相似文献
103.
104.
This article uses the shrinking projection method introduced by Takahashi, Kubota and Takeuchi to propose an iteration algorithm for a countable family of Bregman multi-valued quasi-nonexpansive mappings in order to have the strong convergence under a limit condition in the framework of reflexive Banach spaces. We apply our results to a zero point problem of maximal monotone mappings and equilibrium problems in reflexive Banach spaces. The results presented in the article improve and extend the corresponding results of that found in the literature. 相似文献
105.
M. Ferreira M. M. Rodrigues N. Vieira 《Mathematical Methods in the Applied Sciences》2017,40(18):7033-7050
In this work, we obtain the fundamental solution (FS) of the multidimensional time‐fractional telegraph Dirac operator where the 2 time‐fractional derivatives of orders α∈]0,1] and β∈]1,2] are in the Caputo sense. Explicit integral and series representation of the FS are obtained for any dimension. We present and discuss some plots of the FS for some particular values of the dimension and of the fractional parameters α and β. Finally, using the FS, we study some Poisson and Cauchy problems. 相似文献
106.
Mohsen Miraoui 《Mathematical Methods in the Applied Sciences》2017,40(13):4716-4726
In this article, a new approach for pseudo almost periodic solution under the measure theory, under Acquistpace‐Terreni conditions. We make extensive use of interpolation spaces and exponential dichotomy techniques to obtain the existence of μ‐pseudo almost periodic solutions to some classes of nonautonomous partial evolution equations. For illustration, we propose some application to a nonautonomous heat equation. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
107.
The existence of a positive solution for nonlinear fractional differential equations with integral boundary value conditions 下载免费PDF全文
Alberto Cabada Sladjana Dimitrijevic Tatjana Tomovic Suzana Aleksic 《Mathematical Methods in the Applied Sciences》2017,40(6):1880-1891
In this paper, first, we consider the existence of a positive solution for the nonlinear fractional differential equation boundary value problem where 0≤λ < 1,CDα is the Caputo's differential operator of order α, and f:[0,1] × [0,∞)→[0,∞) is a continuous function. Using some cone theoretic techniques, we deduce a general existence theorem for this problem. Then, we consider two following more general problems for arbitrary α, 1≤n < α≤n + 1: Problem 1: where , 0≤λ < k + 1; Problem 2: where 0≤λ≤α and Dα is the Riemann–Liouville fractional derivative of order α. For these problems, we give existence results, which improve recent results in the literature. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
108.
On the symmetry analysis and conservation laws of the (1 + 1)‐dimensional Hénon–Lane–Emden system 下载免费PDF全文
Ben Muatjetjeja 《Mathematical Methods in the Applied Sciences》2017,40(5):1531-1537
We carry out a complete Lie symmetry analysis and Noether symmetry classification of the (1 + 1)‐dimensional H non–Lane–Emden system. It is shown that the principal Lie algebra, which is one dimensional, extends in several cases. It is also shown that four main cases transpire in the Noether classification with respect to the Lagrangian. In addition, conservation laws for the H non–Lane–Emden system are constructed. Furthermore, we briefly discuss the importance and the physical interpretation of these conserved vectors. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
109.
The interactions between AgnO-(n=1-8) and H2 (or D2) were explored by combination of the mass spectroscopy experiments and density function theory (DFT) calculations. The experiments found that all oxygen atoms in AgnO-(n=1-8) are inert in the interactions with H2 or D2 at the low temperature of 150 K, which is in contrast to their high reactivity with CO under the same condition. These observations are parallel with the preferential oxidation (PROX) of CO in excess hydrogen catalyzed by dispersed silver species in the condensed phase. Possible reaction paths between AgnO-(n=1-8) and H2 were explored using DFT calculations. The results indicated that adsorption of H2 on any site of AgnO-(n=1-8) is extremely weak, and oxidation of H2 by any kind of oxygen in AgnO-(n=1-8) has an apparent barrier strongly dependent on the adsorption style of the "O". These experiments and theoretical results about cluster reactions provided molecule-level insights into the activity of atomic oxygen on real silver catalysts. 相似文献
110.
In this paper, we devote to the study of the existence and multiplicity of solutions of nonlocal systems involving fractional Laplacian with non-differentiable terms using some extended critical point theorems for locally Lipschitz function on product spaces. 相似文献