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   9899篇
  免费   995篇
  国内免费   1205篇
化学   258篇
力学   262篇
综合类   186篇
数学   9175篇
物理学   2218篇
  2024年   21篇
  2023年   108篇
  2022年   115篇
  2021年   167篇
  2020年   253篇
  2019年   346篇
  2018年   303篇
  2017年   316篇
  2016年   350篇
  2015年   254篇
  2014年   512篇
  2013年   821篇
  2012年   437篇
  2011年   582篇
  2010年   559篇
  2009年   752篇
  2008年   740篇
  2007年   737篇
  2006年   634篇
  2005年   561篇
  2004年   465篇
  2003年   479篇
  2002年   463篇
  2001年   292篇
  2000年   320篇
  1999年   310篇
  1998年   264篇
  1997年   240篇
  1996年   148篇
  1995年   82篇
  1994年   81篇
  1993年   49篇
  1992年   44篇
  1991年   36篇
  1990年   22篇
  1989年   25篇
  1988年   22篇
  1987年   8篇
  1986年   9篇
  1985年   21篇
  1984年   27篇
  1983年   16篇
  1982年   25篇
  1981年   14篇
  1980年   22篇
  1979年   12篇
  1978年   10篇
  1977年   6篇
  1976年   5篇
  1936年   4篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
961.
The heat equation is parabolic partial differential equation and occurs in the characterization of diffusion progress. In the present work, a new fractional operator based on the Rabotnov fractional-exponential kernel is considered. Next, we conferred some fascinating and original properties of nominated new fractional derivative with some integral transform operators where all results are significant. The fundamental target of the proposed work is to solve the multidimensional heat equations of arbitrary order by using analytical approach homotopy perturbation transform method and residual power series method, where new fractional operator has been taken in new Yang-Abdel-Aty-Cattani (YAC) sense. The obtained results indicate that solution converges to the original solution in language of generalized Mittag-Leffler function. Three numerical examples are discussed to draw an effective attention to reveal the proficiency and adaptability of the recommended methods on new YAC operator.  相似文献   
962.
963.
This paper is dedicated to studying the following Schrödinger–Poisson system Δ u + V ( x ) u K ( x ) ϕ | u | 3 u = a ( x ) f ( u ) , x 3 , Δ ϕ = K ( x ) | u | 5 , x 3 . Under some different assumptions on functions V(x), K(x), a(x) and f(u), by using the variational approach, we establish the existence of positive ground state solutions.  相似文献   
964.
965.
The present article deals with the similarity method to tackle the fractional Schrӧdinger equation where the derivative is defined in the Riesz sense. Moreover, the procedure of reducing a fractional partial differential equation (FPDE) into an ordinary differential equation (ODE) has been efficiently displayed by means of suitable scaled transform to the proposed fractional equation. Furthermore, the ODEs are treated effectively via the Fourier transform. The graphical solutions are also depicted for different fractional derivatives α .  相似文献   
966.
The complex Hamiltonian systems with real-valued Hamiltonians are generalized to deduce quasi-periodic solutions for a hierarchy of derivative nonlinear Schrödinger (DNLS) equations. The DNLS hierarchy is decomposed into a family of complex finite-dimensional Hamiltonian systems by separating the temporal and spatial variables, and the complex Hamiltonian systems are then proved to be integrable in the Liouville sense. Due to the commutability of complex Hamiltonian flows, the relationship between the DNLS equations and the complex Hamiltonian systems is specified via the Bargmann map. The Abel-Jacobi variable is elaborated to straighten out the DNLS flows as linear superpositions on the Jacobi variety of an invariant Riemann surface. Finally, by using the technique of Riemann-Jacobi inversion, some quasi-periodic solutions are obtained for the DNLS equations in view of the Riemann theorem and the trace formulas.  相似文献   
967.
Based on the inverse scattering method, the formulae of one higher-order pole solitons and multiple higher-order poles solitons of the nonlinear Schrödinger equation (NLS) equation are obtained. Their denominators are expressed as , where is a matrix frequently constructed for solving the Riemann-Hilbert problem, and the asterisk denotes complex conjugate. We take two methods for proving is invertible. The first one shows matrix is equivalent to a self-adjoint Hankel matrix , proving . The second one considers the block-matrix form of , proving . In addition, we prove that the dimension of is equivalent to the sum of the orders of pole points of the transmission coefficient and its diagonal entries compose a set of basis.  相似文献   
968.
In this paper, the aim is to discuss a class of p-Laplacian type fractional Dirichlet"s boundary value problem involving impulsive impacts. Based on the approaches of variational method and the properties of fractional derivatives on the reflexive Banach spaces, the existence results of positive solutions for our equations are established. Two examples are given at the end of each main result.  相似文献   
969.
In this paper, based on inertial and Tseng''s ideas, we propose two projection-based algorithms to solve a monotone inclusion problem in infinite dimensional Hilbert spaces. Solution theorems of strong convergence are obtained under the certain conditions. Some numerical experiments are presented to illustrate that our algorithms are efficient than the existing results.  相似文献   
970.
By using the way of real analysis and the weight functions, a few equivalent statements of a Hilbert-type integral inequality in the whole plane with the internal variables and the best possible constant factor related to the Riemann-zeta function is proved. The operator expression and some particular cases are considered.  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