全文获取类型
收费全文 | 27902篇 |
免费 | 3595篇 |
国内免费 | 1727篇 |
专业分类
化学 | 4879篇 |
晶体学 | 221篇 |
力学 | 8099篇 |
综合类 | 343篇 |
数学 | 10175篇 |
物理学 | 9507篇 |
出版年
2024年 | 43篇 |
2023年 | 267篇 |
2022年 | 469篇 |
2021年 | 464篇 |
2020年 | 686篇 |
2019年 | 614篇 |
2018年 | 638篇 |
2017年 | 895篇 |
2016年 | 956篇 |
2015年 | 797篇 |
2014年 | 1373篇 |
2013年 | 1892篇 |
2012年 | 1323篇 |
2011年 | 1524篇 |
2010年 | 1324篇 |
2009年 | 1473篇 |
2008年 | 1620篇 |
2007年 | 1721篇 |
2006年 | 1544篇 |
2005年 | 1613篇 |
2004年 | 1359篇 |
2003年 | 1360篇 |
2002年 | 1188篇 |
2001年 | 1023篇 |
2000年 | 909篇 |
1999年 | 826篇 |
1998年 | 736篇 |
1997年 | 656篇 |
1996年 | 513篇 |
1995年 | 435篇 |
1994年 | 364篇 |
1993年 | 337篇 |
1992年 | 271篇 |
1991年 | 277篇 |
1990年 | 210篇 |
1989年 | 169篇 |
1988年 | 182篇 |
1987年 | 136篇 |
1986年 | 146篇 |
1985年 | 143篇 |
1984年 | 108篇 |
1983年 | 61篇 |
1982年 | 127篇 |
1981年 | 85篇 |
1980年 | 58篇 |
1979年 | 68篇 |
1978年 | 66篇 |
1977年 | 45篇 |
1976年 | 32篇 |
1971年 | 34篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
On General Mixed Quasivariational Inequalities 总被引:5,自引:0,他引:5
In this paper, we suggest and analyze several iterative methods for solving general mixed quasivariational inequalities by using the technique of updating the solution and the auxiliary principle. It is shown that the convergence of these methods requires either the pseudomonotonicity or the partially relaxed strong monotonicity of the operator. Proofs of convergence is very simple. Our new methods differ from the existing methods for solving various classes of variational inequalities and related optimization problems. Various special cases are also discussed. 相似文献
103.
The rotating flow in the presence of a magnetic field is a problem belonging to hydromagnetics and deserves to be more widely studied than it has been to date. In the non‐linear regime the literature is scarce. We develop the governing equations for the unsteady hydromagnetic rotating flow of a fourth‐order fluid past a porous plate. The steady flow is governed by a boundary value problem in which the order of differential equations is more than the number of available boundary conditions. It is shown that by augmenting the boundary conditions based on asymptotic structures at infinity it is possible to obtain numerical solutions of the nonlinear hydromagnetic equations. Effects of uniform suction or blowing past the porous plate, exerted magnetic field and rotation on the flow phenomena, especially on the boundary layer structure near the plate, are numerically analysed and discussed. The flow behaviours of the Newtonian fluid and second‐, third‐ and fourth‐order non‐Newtonian fluids are compared for the special flow problem, respectively. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
104.
M. A. Efendiev J. Fuhrmann S. V. Zelik 《Mathematical Methods in the Applied Sciences》2004,27(8):907-930
For the Boussinesq approximation of the equations of coupled heat and fluid flow in a porous medium we show that the corresponding system of partial differential equations possesses a global attractor. We give lower and upper bounds of the Hausdorff dimension of the attractor depending on a physical parameter of the system, namely the Rayleigh number of the flow. Numerical experiments confirm the theoretical findings and raise new questions on the structure of the solutions of the system. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
105.
In this paper, a generalized anti–maximum principle for the second order differential operator with potentials is proved. As an application, we will give a monotone iterative scheme for periodic solutions of nonlinear second order equations. Such a scheme involves the Lp norms of the growth, 1 ≤ p ≤ ∞, while the usual one is just the case p = ∞. 相似文献
106.
Sufficient conditions are established for the asymptotic behavior of solutionsof nonlinear delay differential equations x′(t)+sum from i=1 to m(pi(t)x(t-т_i))=F(t,x_t),t≥0where 0<т_1<т_2<…<т_m≤r,pi∈C([0,∞)),i=1,2,…,m,F∈C([0,∞)×C_0,R).C_0=C([-r,0],R)equipped with the sup norm ||·|| forsome r>0. A new result is established, some known results are improved. 相似文献
107.
带有给定凸切线多边形的保形五次样条逼近 总被引:3,自引:0,他引:3
本讨论带有给定切线多边形的保形逼近问题.给出了一条与给定切线多边形相切的保形五次参数祥条曲线。 相似文献
108.
Norikazu Yamaguchi 《Mathematical Methods in the Applied Sciences》2005,28(13):1507-1526
In this paper we are concerned with the initial boundary value problem of the micropolar fluid system in a three dimensional bounded domain. We study the resolvent problem of the linearized equations and prove the generation of analytic semigroup and its time decay estimates. In particular, Lp–Lq type estimates are obtained. By use of the Lp–Lq estimates for the semigroup, we prove the existence theorem of global in time solution to the original nonlinear problem for small initial data. Furthermore, we study the magneto‐micropolar fluid system in the final section. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
109.
Zhu Yongliang; Pagilla Prabhakar R. 《IMA Journal of Mathematical Control and Information》2005,22(2):181-186
We derive some useful and easily computable necessary conditionsfor the existence of a positive semi-definite solution to thealgebraic Ricatti equation (ARE). A motivating example is givento highlight the usefulness of the conditions for controllerand observer designs for nonlinear systems. Further, an upperbound on the trace of the solution to the ARE is also derived. 相似文献
110.
We consider a splitting finite-difference scheme for an initial-boundary value problem for a two-dimensional nonlinear evolutionary
equation. The problem is split into nonlinear and linear parts. The linear part is also split into locally one-dimensional
equations. We prove the convergence and stability of the scheme in L
2 and C norms.
Printed in Lietuvos Matematikos Rinkinys, Vol. 45, No. 3, pp. 413–434, July–September, 2005. 相似文献