全文获取类型
收费全文 | 14619篇 |
免费 | 1411篇 |
国内免费 | 1436篇 |
专业分类
化学 | 3549篇 |
晶体学 | 226篇 |
力学 | 1911篇 |
综合类 | 240篇 |
数学 | 9123篇 |
物理学 | 2417篇 |
出版年
2024年 | 34篇 |
2023年 | 144篇 |
2022年 | 169篇 |
2021年 | 244篇 |
2020年 | 369篇 |
2019年 | 333篇 |
2018年 | 316篇 |
2017年 | 380篇 |
2016年 | 415篇 |
2015年 | 313篇 |
2014年 | 594篇 |
2013年 | 1027篇 |
2012年 | 746篇 |
2011年 | 865篇 |
2010年 | 855篇 |
2009年 | 927篇 |
2008年 | 998篇 |
2007年 | 1069篇 |
2006年 | 873篇 |
2005年 | 808篇 |
2004年 | 730篇 |
2003年 | 768篇 |
2002年 | 641篇 |
2001年 | 504篇 |
2000年 | 474篇 |
1999年 | 422篇 |
1998年 | 380篇 |
1997年 | 313篇 |
1996年 | 263篇 |
1995年 | 235篇 |
1994年 | 196篇 |
1993年 | 138篇 |
1992年 | 133篇 |
1991年 | 108篇 |
1990年 | 92篇 |
1989年 | 68篇 |
1988年 | 67篇 |
1987年 | 52篇 |
1986年 | 57篇 |
1985年 | 59篇 |
1984年 | 47篇 |
1983年 | 24篇 |
1982年 | 55篇 |
1981年 | 43篇 |
1980年 | 30篇 |
1979年 | 25篇 |
1978年 | 16篇 |
1977年 | 9篇 |
1976年 | 11篇 |
1972年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
This paper considers a problem of nonlinear programming in which the objective function is the ratio of two linear functions and the constraints define a bounded and connected feasible region. Using a coordinate transformation, this problem is transformed into a simpler one, whose geometric interpretation is of particular significance. The transformation leads to a characterization of some special vertices of the feasible region from both the theoretical and operational points of view. 相似文献
62.
63.
Existence of positive solution is established for boundary value problems of non-singular for a class quasi-linear ordinary differential equation on the semi-infinite interval. The results are obtained by using the nonlinear alternative of Leray-Schauder method. 相似文献
64.
Tatsien Li 《Mathematical Methods in the Applied Sciences》2006,29(13):1543-1553
By means of a direct and constructive method based on the theory of semi‐global C2 solution, the local exact boundary observability and an implicit duality between the exact boundary controllability and the exact boundary observability are shown for 1‐D quasilinear wave equations with various boundary conditions. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
65.
A. B. Vasil’eva A. A. Plotnikov 《Computational Mathematics and Mathematical Physics》2006,46(5):762-767
A singularly perturbed parabolic equation with a nonlinear right-hand side of a special form is examined. A numerical analytical study of such equations is performed. 相似文献
66.
P. De Maesschalck 《Journal of Differential Equations》2007,238(2):338-365
By applying geometric techniques to real analytic singularly perturbed vector fields on the plane, we develop a way to give a bound on the Gevrey type of the Taylor development of canard manifolds at degenerate planar turning points. By blowing up the phase space at the turning point, we find asymptotic estimates even when such expansions w.r.t. traditional phase space variables do not exist. The asymptotic estimates are then used to give a sufficient and necessary condition on the existence of (local) canard solutions. 相似文献
67.
D.L. Skuratov Yu.L. Ratis I.A. Selezneva J. Pérez P. Fernández de Córdoba J.F. Urchueguía 《Applied Mathematical Modelling》2007
This paper deals with modelling the workpiece temperature field produced during the grinding process. The proposed model is given in terms of a two-dimensional boundary-value problem where the interdependence among the grinding wheel, the workpiece and the coolant is described by two variable functions in the boundary condition. An explicit integral form solution is constructed using the Laplace and Fourier transforms and the Green’s function method. 相似文献
68.
The purpose of this work is to investigate the weakened Ambrosetti–Prodi type multiplicity results for weak doubly periodic solutions of damped beam equations. By using the topological degree theory, the author obtains a result which is similar to the result for damped wave equations in the literature. 相似文献
69.
程建纲 《数学物理学报(A辑)》2005,25(4):482-488
该文考虑两点边值问题[1/q(t)][q(t)y′(t)]′+p(t)f(y(t))= 0,λ_1 y(α)-λ_2y′(α)=0 and y(β)=B非负解的存在性, 其中p(t)可能在t=α或t=β附近具有奇异性, f(0)≥0,
lim_(y→+∞)f(y)/y=+∞, 并且存在y>0, 使得f(y)<0. 相似文献
70.