全文获取类型
收费全文 | 10013篇 |
免费 | 828篇 |
国内免费 | 521篇 |
专业分类
化学 | 1297篇 |
晶体学 | 144篇 |
力学 | 907篇 |
综合类 | 82篇 |
数学 | 7192篇 |
物理学 | 1740篇 |
出版年
2024年 | 14篇 |
2023年 | 82篇 |
2022年 | 106篇 |
2021年 | 123篇 |
2020年 | 264篇 |
2019年 | 265篇 |
2018年 | 264篇 |
2017年 | 274篇 |
2016年 | 293篇 |
2015年 | 239篇 |
2014年 | 439篇 |
2013年 | 949篇 |
2012年 | 374篇 |
2011年 | 576篇 |
2010年 | 578篇 |
2009年 | 655篇 |
2008年 | 705篇 |
2007年 | 643篇 |
2006年 | 555篇 |
2005年 | 504篇 |
2004年 | 428篇 |
2003年 | 386篇 |
2002年 | 346篇 |
2001年 | 271篇 |
2000年 | 222篇 |
1999年 | 223篇 |
1998年 | 174篇 |
1997年 | 165篇 |
1996年 | 149篇 |
1995年 | 129篇 |
1994年 | 108篇 |
1993年 | 84篇 |
1992年 | 75篇 |
1991年 | 55篇 |
1990年 | 49篇 |
1989年 | 36篇 |
1988年 | 43篇 |
1987年 | 26篇 |
1986年 | 46篇 |
1985年 | 48篇 |
1984年 | 56篇 |
1983年 | 42篇 |
1982年 | 52篇 |
1981年 | 43篇 |
1980年 | 42篇 |
1979年 | 48篇 |
1978年 | 32篇 |
1977年 | 18篇 |
1976年 | 20篇 |
1973年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
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
72.
Rong Cheng 《Applicable analysis》2017,96(5):778-798
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
73.
74.
Christopher C. Tisdell 《International Journal of Mathematical Education in Science & Technology》2017,48(5):794-801
Knowing an equation has a unique solution is important from both a modelling and theoretical point of view. For over 70 years, the approach to learning and teaching ‘well posedness’ of initial value problems (IVPs) for second- and higher-order ordinary differential equations has involved transforming the problem and its analysis to a first-order system of equations. We show that this excursion is unnecessary and present a direct approach regarding second- and higher-order problems that does not require an understanding of systems. 相似文献
75.
《Mathematische Nachrichten》2017,290(17-18):2995-3005
In this sequel to the article 17 , a criterion for the regularity of fundamental solutions of differential operators with positive symbol is proved in analogy to Hörmander's criteria, see 9 , 12 . It implies that the temperate fundamental solution of the operator is not regular. Furthermore, a formula for the convolution of two ‐invariant distributions is presented, and, finally, L. Schwartz' question on the surjectivity of linear partial differential operators with constant coefficients on the space is completely answered in the case of ‐invariant differential operators. 相似文献
76.
On the existence of positive least energy solutions for a coupled Schrödinger system with critical exponent 下载免费PDF全文
Hongyu Ye 《Mathematical Methods in the Applied Sciences》2017,40(4):1032-1043
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
77.
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
78.
AbstractCertain notions of approximate weak efficient solutions are considered for a set-valued optimization problem based on vector and set criteria approaches. For approximate solutions based on the vector approach, a characterization is provided in terms of an extended Gerstewitz’s function. For the set approach case, two notions of approximate weak efficient solutions are introduced using a lower and an upper quasi order relations for sets and further compactness and stability aspects are discussed for these approximate solutions. Existence and scalarization using a generalized Gerstewitz’s function are also established for approximate solutions, based on the lower set order relation. 相似文献
79.
Ground state solutions and geometrically distinct solutions for generalized quasilinear Schrödinger equation 下载免费PDF全文
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
80.
Existence of multiplicity harmonic and subharmonic solutions for second‐order quasilinear equation via Poincaré‐Birkhoff twist theorem 下载免费PDF全文
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