首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   10288篇
  免费   812篇
  国内免费   572篇
化学   1412篇
晶体学   148篇
力学   756篇
综合类   73篇
数学   7562篇
物理学   1721篇
  2024年   14篇
  2023年   93篇
  2022年   115篇
  2021年   128篇
  2020年   279篇
  2019年   271篇
  2018年   271篇
  2017年   272篇
  2016年   277篇
  2015年   242篇
  2014年   452篇
  2013年   1021篇
  2012年   392篇
  2011年   587篇
  2010年   565篇
  2009年   693篇
  2008年   729篇
  2007年   653篇
  2006年   571篇
  2005年   509篇
  2004年   441篇
  2003年   403篇
  2002年   347篇
  2001年   273篇
  2000年   236篇
  1999年   227篇
  1998年   185篇
  1997年   177篇
  1996年   155篇
  1995年   123篇
  1994年   117篇
  1993年   85篇
  1992年   72篇
  1991年   62篇
  1990年   49篇
  1989年   36篇
  1988年   42篇
  1987年   25篇
  1986年   44篇
  1985年   48篇
  1984年   56篇
  1983年   43篇
  1982年   51篇
  1981年   44篇
  1980年   38篇
  1979年   46篇
  1978年   32篇
  1977年   21篇
  1976年   20篇
  1973年   12篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
71.
In this paper, we consider the following coupled Schrödinger system with critical exponent: where is a smooth bounded domain, λ > 0,μ≥0, and . Under certain conditions on λ and μ, we show that this problem has at least one positive least energy solution. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
72.
This paper is concerned with the following systems of Kirchhoff‐type equations: Under more relaxed assumptions on V(x) and F(x,u,v), we first prove the existence of at least two nontrivial solutions for the aforementioned system by using Morse theory in combination with local linking arguments. Then by using the Clark theorem, the existence results of at least 2k distinct pairs of solutions are obtained. Some recent results from the literature are extended. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
73.
In this paper, we study the following generalized quasilinear Schrödinger equation where N≥3, is a C1 even function, g(0) = 1 and g(s) > 0 for all s > 0. Under some suitable conditions, we prove that the equation has a ground state solution and infinitely many pairs ±u of geometrically distinct solutions. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
74.
75.
In this paper, we study the existence and concentration of positive solution of a class of coupled Schrödinger equations. We admit that the potentials may not be non-negative and suppose that the intersection of the sets has positive Lebesgue measure. By studying the modified functional of the associated functional carefully, we establish the existence of positive least energy solutions for the coupled Schrödinger system. Moreover, we prove the concentration phenomenon of the positive solution when the parameter goes to infinity.  相似文献   
76.
In this paper, we firstly establish the existence theorem of the global weak solutions of the Cauchy problem for the shallow water wave model of moderate amplitude, then following the idea in Xin and Zhang’s work (see Xin and Zhang, 2002), we prove the uniqueness of global weak solutions using the localization analysis in the transport equation theory. Finally, several travelling wave solutions are derived.  相似文献   
77.
Ice has a variety of scientifically interesting features, some of which have not been reasonably interpreted despite substantial efforts by researchers. Most chemical studies of ice have focused on the elucidation of its physicochemical nature and its roles in the natural environment. Ice often contains impurities, such as salts, and in such cases, a liquid phase coexists with solid ice over a wide temperature range. This impure ice also acts as a cryoreactor, governing the circulation of chemical species of environmental importance. Reactions and phenomena occurring in this liquid phase show features different from those seen in normal bulk aqueous solutions. In the present account, we discuss the chemical characteristics of the liquid phase that develops in a frozen aqueous phase and show how novel analytical systems can be designed based on he features of the liquid phase which are predictable in some cases but unpredictable in others.  相似文献   
78.
79.
We consider a transmission problem consisting of two semilinear parabolic equations involving fractional diffusion operators of different orders in a general non-smooth setting with emphasis on Lipschitz interfaces and transmission conditions along the interface. We give a unified framework for the existence and uniqueness of strong and mild solutions, and their global regularity properties.  相似文献   
80.
In this paper, we investigate the existence and multiplicity of harmonic and subharmonic solutions for second‐order quasilinear equation where , g satisfies the superlinear condition at infinity. We prove that the given equation possesses harmonic and subharmonic solutions by using the phase‐plane analysis methods and a generalized version of the Poincaré‐Birkhoff twist theorem.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号