全文获取类型
收费全文 | 16933篇 |
免费 | 1739篇 |
国内免费 | 1625篇 |
专业分类
化学 | 3781篇 |
晶体学 | 239篇 |
力学 | 2291篇 |
综合类 | 268篇 |
数学 | 10629篇 |
物理学 | 3089篇 |
出版年
2024年 | 43篇 |
2023年 | 160篇 |
2022年 | 199篇 |
2021年 | 280篇 |
2020年 | 427篇 |
2019年 | 406篇 |
2018年 | 383篇 |
2017年 | 466篇 |
2016年 | 494篇 |
2015年 | 378篇 |
2014年 | 682篇 |
2013年 | 1244篇 |
2012年 | 841篇 |
2011年 | 980篇 |
2010年 | 962篇 |
2009年 | 1054篇 |
2008年 | 1170篇 |
2007年 | 1219篇 |
2006年 | 1009篇 |
2005年 | 930篇 |
2004年 | 823篇 |
2003年 | 893篇 |
2002年 | 737篇 |
2001年 | 604篇 |
2000年 | 561篇 |
1999年 | 500篇 |
1998年 | 451篇 |
1997年 | 365篇 |
1996年 | 308篇 |
1995年 | 260篇 |
1994年 | 233篇 |
1993年 | 166篇 |
1992年 | 148篇 |
1991年 | 119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 | 67篇 |
1981年 | 51篇 |
1980年 | 37篇 |
1979年 | 30篇 |
1978年 | 18篇 |
1977年 | 13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 0 毫秒
41.
The equivalence of three (2 1)-dimensional soliton equations is proved, and the quite generalsolutionswitha some arbitrary functions of x, t and y respectively are obtained. By selecting the arbitrary functions, many specialtypes of the localized excitations like the solitoff solitons, multi-dromion solutions, lump, and multi-ring soliton solutionsare obtained. 相似文献
42.
In this paper, nonconvex multiobjective optimization problems are studied. New characterizations of a properly efficient solution in the sense of Geoffrion's are established in terms of the stability of one scalar optimization problem and the existence of an exact penalty function of a scalar constrained program, respectively. One of the characterizations is applied to derive necessary conditions for a properly efficient control-parameter pair of a nonconvex multiobjective discrete optimal control problem with linear constraints. 相似文献
43.
We present integral-type Darboux transformation for the mKdV hierarchy and for the mKdV hierarchy withself-consistent sources. In contrast with the normal Darboux transformation, the integral-type Darboux transformationscan offer non-auto-Backlund transformation between two (2n 1)-th mKdV equations with self-consistent sources withdifferent degrees. This kind of Darboux transformation enables us to construct the N-soliton solution for the mKdVhierarchy with self-consistent sources. We also propose the formulas for the m times repeated integral-type Darbouxtransformations for both mKdV hierarchy and mKdV hierarchy with self-consistent sources. 相似文献
44.
YAN Zhen-Ya 《理论物理通讯》2002,38(10)
Recently, we obtained thirteen families of Jacobian elliptic function solutions of mKdV equation by usingour extended Jacobian elliptic function expansion method. In this note, the mKdV equation is investigated and anotherthree families of new doubly periodic solutions (Jacobian elliptic function solutions) are fbund again by using a newtransformation, which and our extended Jacobian elliptic function expansion method form a new method still called theextended Jacobian elliptic function expansion method. The new method can be more powertul to be applied to othernonlinear differential equations. 相似文献
45.
Kai-li Xiang 《计算数学(英文版)》2002,(2)
1. IntroductionWe consider a class of direct hybrid methods proposed in [11 for solving the second orderinitial value problemy" = f(t,y), y(0),y'(0) given (1.1)The basic method has the formandHere t. = nh and we define t.l.. = t. I aih, i = 1, 2 and n=0,1… 相似文献
46.
Hua Nie Jian-hua Wu 《应用数学学报(英文版)》2006,22(2):257-264
This paper is concerned with the unstirred chemostat model with two-species and one non-reproducingresource.The global attractivity of the positive steady-state solutions of the original system is established.Moreover,the effects of the growth rate on the unique positive equilibrium of the single population model arestudied. 相似文献
47.
Recently, molecular imaging has been rapidly developed to studyphysiological and pathological processes in vivo at the cellularand molecular levels. Among molecular imaging modalities, opticalimaging has attracted a major attention for its unique advantages.In this paper, we establish a mathematical framework for multispectralbioluminescence tomography (BLT) that allows simultaneous studiesof multiple optical reporters. We show solution existence, uniquenessand continuous dependence on data as well as the limiting behaviourswhen the regularization parameter approaches zero or when thepenalty parameter approaches infinity. Then, we propose twonumerical schemes for multispectral BLT and derive error estimatesfor the corresponding solutions. 相似文献
48.
49.
Piotr Szopa 《Mathematical Methods in the Applied Sciences》2007,30(3):331-346
In this paper, we prove the existence and uniqueness of a global solution for 2‐D micropolar fluid equation with periodic boundary conditions. Then we restrict ourselves to the autonomous case and show the existence of a global attractor. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
50.
Banach空间二阶周期边值问题解的存在性 总被引:2,自引:0,他引:2
利用一些比较结果,讨论了Banach空间中二阶周期边值问题解的存在性,获得了若干解的存在性与唯一性结果。 相似文献