全文获取类型
收费全文 | 16368篇 |
免费 | 1295篇 |
国内免费 | 780篇 |
专业分类
化学 | 308篇 |
晶体学 | 9篇 |
力学 | 2270篇 |
综合类 | 107篇 |
数学 | 12744篇 |
物理学 | 3005篇 |
出版年
2024年 | 37篇 |
2023年 | 174篇 |
2022年 | 136篇 |
2021年 | 240篇 |
2020年 | 454篇 |
2019年 | 441篇 |
2018年 | 448篇 |
2017年 | 433篇 |
2016年 | 422篇 |
2015年 | 395篇 |
2014年 | 700篇 |
2013年 | 1778篇 |
2012年 | 631篇 |
2011年 | 947篇 |
2010年 | 762篇 |
2009年 | 1065篇 |
2008年 | 1034篇 |
2007年 | 965篇 |
2006年 | 887篇 |
2005年 | 675篇 |
2004年 | 619篇 |
2003年 | 612篇 |
2002年 | 608篇 |
2001年 | 485篇 |
2000年 | 491篇 |
1999年 | 443篇 |
1998年 | 373篇 |
1997年 | 355篇 |
1996年 | 263篇 |
1995年 | 181篇 |
1994年 | 170篇 |
1993年 | 140篇 |
1992年 | 103篇 |
1991年 | 92篇 |
1990年 | 80篇 |
1989年 | 60篇 |
1988年 | 46篇 |
1987年 | 49篇 |
1986年 | 37篇 |
1985年 | 64篇 |
1984年 | 101篇 |
1983年 | 50篇 |
1982年 | 64篇 |
1981年 | 64篇 |
1980年 | 58篇 |
1979年 | 56篇 |
1978年 | 54篇 |
1977年 | 33篇 |
1976年 | 27篇 |
1974年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The extended tanh method with a computerized symbolic computation is used for constructing the traveling wave solutions of coupled nonlinear equations arising in physics. The obtained solutions include solitons, kinks and plane periodic solutions. The applied method will be used to solve the generalized coupled Hirota Satsuma KdV equation. 相似文献
992.
993.
This research study deals with the numerical solutions of linear and nonlinear time-fractional subdiffusion equations of distributed order. The main aim of our approach is based on the hybrid of block-pulse functions and shifted Legendre polynomials. We produce a novel and exact operational vector for the fractional Riemann–Liouville integral and use it via the Gauss–Legendre quadrature formula and collocation method. Consequently, we reduce the proposed equations to systems of equations. The convergence and error bounds for the new method are investigated. Six problems are tested to confirm the accuracy of the proposed approach. Comparisons between the obtained numerical results and other existing methods are provided. Numerical experiments illustrate the reliability, applicability, and efficiency of the proposed method. 相似文献
994.
In this work, we give sufficient conditions for the existence and uniqueness of μ?pseudo almost periodic integral solutions for some neutral partial functional differential equations with Stepanov μ?pseudo almost periodic forcing functions. Our working tools are based on the variation of constant formula and the spectral decomposition of the phase space. To illustrate our main results, we give applications to a neutral model arising in physical systems, as well as an application to heat equations with discrete and continuous delay. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
995.
Two efficient recursive algorithms epsilon- algorithm and eta-algorithm are approximants were used to accelerate the convergence of the power series with functionvalued coefficients and to estimate characteristic value of the integral equations. Famous two algorithms. 相似文献
996.
The present paper makes use of a wave equation formulation of the primitive shallow water equations to simulate one-dimensional free surface flow. A numerical formulation of the boundary element method is then developed to solve the wave continuity equation using a time-dependent fundamental solution, while an explicit finite difference scheme is used to derive velocities from the primitive momentum equation. One-dimensional free surface flows in open channels are treated and the results compared with analytical and numerical solutions. © 1997 John Wiley & Sons, Ltd. 相似文献
997.
998.
Formulas for calculating Legendre functions and associated Legendre functions of the first kind of complex degree using an Ermakov—Lewis invariant are presented. These formulas are straight-forward to implement numerically and are motivated by the lack of computational routines in standard university tools like those of MatLab and Maple. Angular waves propagating in opposite directions are also obtained. The results are particularly useful in complex angular momentum theories and nearside/farside analysis of spin-dependent angular scattering from central potentials. 相似文献
999.
This paper is concerned with a stabilized finite element method
based on two local Gauss integrations for the two-dimensional
non-stationary conduction-convection equations by using the lowest
equal-order pairs of finite elements. This method only offsets the
discrete pressure space by the residual of the simple and symmetry
term at element level in order to circumvent the inf-sup condition.
The stability of the discrete scheme is derived under some
regularity assumptions. Optimal error estimates are obtained by
applying the standard Galerkin techniques. Finally, the numerical
illustrations agree completely with the theoretical expectations. 相似文献
1000.
The lower bounds of life span of classical solutions to one‐dimensional initial‐Neumann boundary value problems for general quasilinear wave equations
下载免费PDF全文
![点击此处可从《Mathematical Methods in the Applied Sciences》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Wei Han 《Mathematical Methods in the Applied Sciences》2016,39(4):906-929
In this paper, we will study the lower bounds of the life span (the maximal existence time) of solutions to the initial‐boundary value problems with small initial data and zero Neumann boundary data on exterior domain for one‐dimensional general quasilinear wave equations utt?uxx=b(u,Du)uxx+F(u,Du). Our lower bounds of the life span of solutions in the general case and special case are shorter than that of the initial‐Dirichlet boundary value problem for one‐dimensional general quasilinear wave equations. We clarify that although the lower bounds in this paper are same as that in the case of Robin boundary conditions obtained in the earlier paper, however, the results in this paper are not the trivial generalization of that in the case of Robin boundary conditions because the fundamental Lemmas 2.4, 2.5, 2.6, and 2.7, that is, the priori estimates of solutions to initial‐boundary value problems with Neumann boundary conditions, are established differently, and then the specific estimates in this paper are different from that in the case of Robin boundary conditions. Another motivation for the author to write this paper is to show that the well‐posedness of problem 1.1 is the essential precondition of studying the lower bounds of life span of classical solutions to initial‐boundary value problems for general quasilinear wave equations. The lower bound estimates of life span of classical solutions to initial‐boundary value problems is consistent with the actual physical meaning. Finally, we obtain the sharpness on the lower bound of the life span 1.8 in the general case and 1.10 in the special case. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献