全文获取类型
收费全文 | 17236篇 |
免费 | 1785篇 |
国内免费 | 1641篇 |
专业分类
化学 | 3758篇 |
晶体学 | 239篇 |
力学 | 2270篇 |
综合类 | 270篇 |
数学 | 11108篇 |
物理学 | 3017篇 |
出版年
2024年 | 35篇 |
2023年 | 155篇 |
2022年 | 184篇 |
2021年 | 280篇 |
2020年 | 428篇 |
2019年 | 413篇 |
2018年 | 386篇 |
2017年 | 472篇 |
2016年 | 498篇 |
2015年 | 383篇 |
2014年 | 697篇 |
2013年 | 1346篇 |
2012年 | 848篇 |
2011年 | 993篇 |
2010年 | 978篇 |
2009年 | 1094篇 |
2008年 | 1208篇 |
2007年 | 1240篇 |
2006年 | 1032篇 |
2005年 | 942篇 |
2004年 | 839篇 |
2003年 | 903篇 |
2002年 | 740篇 |
2001年 | 611篇 |
2000年 | 567篇 |
1999年 | 507篇 |
1998年 | 460篇 |
1997年 | 369篇 |
1996年 | 314篇 |
1995年 | 265篇 |
1994年 | 236篇 |
1993年 | 166篇 |
1992年 | 149篇 |
1991年 | 118篇 |
1990年 | 98篇 |
1989年 | 73篇 |
1988年 | 78篇 |
1987年 | 63篇 |
1986年 | 64篇 |
1985年 | 72篇 |
1984年 | 57篇 |
1983年 | 32篇 |
1982年 | 69篇 |
1981年 | 51篇 |
1980年 | 37篇 |
1979年 | 31篇 |
1978年 | 18篇 |
1977年 | 14篇 |
1976年 | 16篇 |
1972年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
121.
122.
本文利用比较定理,控制收敛定理和积分平均的方法,讨论一类具有无限时滞的非自治,非卷积的捕食者-食饵系统的一致持久性和正周期解。 相似文献
123.
In this paper, by the use of a fixed point theorem, many new necessary and sufficient conditions for the existence of positive solutions in C[0,1]∩C1[0,1]∩C2(0,1) or C[0,1]∩C2(0,1) are presented for singular superlinear and sublinear second-order boundary value problems. Singularities at t=0, t=1 will be discussed. 相似文献
124.
Zhimin He 《Journal of Mathematical Analysis and Applications》2004,296(1):97-109
In this paper, by means of a new twin fixed-point theorem in a cone, the existence of at least two positive solutions of m-point boundary value problem for second order dynamic equations on time scales is considered. 相似文献
125.
Nguyen Minh Chuong Bui Kien Cuong 《Proceedings of the American Mathematical Society》2004,132(12):3589-3597
A class of Cauchy problems for interesting complicated periodic pseudodifferential equations is considered. By the Galerkin-wavelet method and with weak solutions one can find sufficient conditions to establish convergence estimates of weak Galerkin-wavelet solutions to a Cauchy problem for this class of equations.
126.
Using the iterative scheme we prove the local existence and uniqueness of solutions of the spherically symmetric Einstein-Vlasov-Maxwell system with small initial data. We prove a continuation criterion to global in-time solutions. 相似文献
127.
Alfonso Carriazo Luis M. Ferná ndez 《Proceedings of the American Mathematical Society》2004,132(11):3327-3336
In this paper we present an interesting relationship between graph theory and differential geometry by defining submanifolds of almost Hermitian manifolds associated with certain kinds of graphs. We show some results about the possibility of a graph being associated with a submanifold and we use them to characterize CR-submanifolds by means of trees. Finally, we characterize submanifolds associated with graphs in a four-dimensional almost Hermitian manifold.
128.
YAN Zhen-Ya 《理论物理通讯》2003,39(2)
More recently, sixteen families of Jacobian elliptic function solutions of mKdV equation have been foundby using our extended Jacobian elliptic function expansion method. In this paper, we continue to improve our methodby using another eight pairs of the closed Jacobian elliptic functions. The mKdV equation is chosen to illustrate theimproved method such that another eight families of new Jacobian elliptic function solutions are obtained again. Thenew method can be more powerful to be applied to other nonlinear differential equations. 相似文献
129.
The periodic precipitation pattern formation in gelatinous media is interpreted as a moving boundary problem. The time law,
spacing law and width law are revisited on the basis of the new scenario. The explicit dependence of the geometric structure
on the initial concentrations of the reactants is derived. Matalon—Packter law, which relates the spacing coefficient with
the initial concentrations is reformulated removing many ambiguities and impractical parameters. Experimental results are
discussed to establish the significance of moving boundary concept in the diffusion controlled pattern forming systems 相似文献
130.
周忆 《数学年刊B辑(英文版)》2003,24(3)
This paper considers the following Cauchy problem for semilinear wave equations in n spacedimensions□φ = F( φ),φ(0, x) = f(x), tφ(0, x) = g(x),The minimal value of s is determined such that the above Cauchy problem is locally well-posed in Hs. It turns out that for the general equation s must satisfyThis is due to Ponce and Sideris (when n = 3) and Tataru (when n ≥ 5). The purpose of thispaper is to supplement with a proof in the case n = 2, 4. 相似文献