全文获取类型
收费全文 | 6969篇 |
免费 | 657篇 |
国内免费 | 677篇 |
专业分类
化学 | 640篇 |
晶体学 | 24篇 |
力学 | 396篇 |
综合类 | 159篇 |
数学 | 6210篇 |
物理学 | 874篇 |
出版年
2024年 | 11篇 |
2023年 | 48篇 |
2022年 | 115篇 |
2021年 | 154篇 |
2020年 | 141篇 |
2019年 | 155篇 |
2018年 | 143篇 |
2017年 | 222篇 |
2016年 | 237篇 |
2015年 | 145篇 |
2014年 | 320篇 |
2013年 | 534篇 |
2012年 | 332篇 |
2011年 | 416篇 |
2010年 | 356篇 |
2009年 | 457篇 |
2008年 | 477篇 |
2007年 | 508篇 |
2006年 | 419篇 |
2005年 | 367篇 |
2004年 | 351篇 |
2003年 | 305篇 |
2002年 | 294篇 |
2001年 | 247篇 |
2000年 | 236篇 |
1999年 | 180篇 |
1998年 | 192篇 |
1997年 | 168篇 |
1996年 | 148篇 |
1995年 | 94篇 |
1994年 | 83篇 |
1993年 | 52篇 |
1992年 | 43篇 |
1991年 | 44篇 |
1990年 | 38篇 |
1989年 | 22篇 |
1988年 | 22篇 |
1987年 | 20篇 |
1986年 | 13篇 |
1985年 | 25篇 |
1984年 | 23篇 |
1983年 | 32篇 |
1982年 | 21篇 |
1981年 | 25篇 |
1980年 | 23篇 |
1979年 | 17篇 |
1978年 | 14篇 |
1977年 | 4篇 |
1973年 | 2篇 |
1959年 | 2篇 |
排序方式: 共有8303条查询结果,搜索用时 15 毫秒
101.
We use boundary value methods to compute consistent initial values for fully implicit nonlinear differential-algebraic equations.
The obtained algorithm uses variable order formulae and a deferred correction technique to evaluate the error. A rigorous
theory is stated for nonlinear index 1, 2 and 3 DAEs of Hessenberg form. Numerical tests on classical index 1, 2 and 3 DAE
problems are reported.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
102.
TANGWEIJUN 《高校应用数学学报(英文版)》1997,12(4):427-440
In this paper, a new method of boundary reduction is proposed, which reduces thesteady-state heat transfer equation with radiation. Moreover, a boundary element method is pre-sented for its solution and the error estimates of the numerical approximations are given. 相似文献
103.
104.
This paper presents an algorithm and the supporting theory for solving a class of nonlinear multiple criteria optimization problems using Zionts—Wallenius type of interaction. The Zionts—Wallenius method, as extended in this paper, can be used for solving multiple criteria problems with concave objective and (implicit) value functions and convex feasible regions. Modifications of the method to handle nonconvex feasible regions and general nonlinear objective functions are also discussed.This research was supported, in part, by a Faculty Research Development Award and by a Council of 100 Research Grant from Arizona State University (Roy), and by a grant from Y. Jahnsson Foundation, Finland (Wallenius). The research was performed while the second author was a Visiting Professor at Arizona State University. 相似文献
105.
The reference [4] proved the consistency of S1 and S2 among Lewis' five strict implication systems in the modal logic by using the method of the Boolean-valued model. But, in this method, the consistency of S3, S4 and S5 in Lewis' five strict implication systems is not decided. This paper makes use of the properties: (1) the equivalence of the modal systems S3 and P3, S4 and P4; (2) the modal systems P3 and P4 all contained the modal axiom T(□p → p); (3) the modal axiom T is correspondence to the reflexive property in VB. Hence, the paper proves: (a) ‖As31‖ = 1; (b) ‖AS41‖ = 1; (c) ‖AS5l‖ = 1 in the model (where B is a complete Boolean algebra, R is reflexive property in VB). Therefore, the paper finally proves that the Boolean-valued model VB of the ZFC axiom system in set theory is also a Boolean-valued model of Lewis' the strict implication system S3, S4 and S5. 相似文献
106.
蔡建平 《Annals of Differential Equations》2004,20(1):14-20
This paper investigates the periodic boundary value problems for a class of second order functional differential equations. The monotone iterative technique and the maximum principle are applied to obtain the existence of maximal and minimal solutions. 相似文献
107.
§1 IntroductionAt present,boundary value problems (BVPs) are widely investigated with variousmethods and techniques. BVPs with integral boundary conditions constitute a veryinteresting class of problems such as multipoint,three-point,four-point and nonlocalboundary value problems which are considered by many authors.And the existence ofpositive solutions for these problems becomes the subjectof many papers[1—6] .In a recentpaper[7] ,the authors have studied the existence of positive solut… 相似文献
108.
基于CVaR风险计量技术,分别给出了正态和t分布情形下资产组合的CVaR值,对一般情形下风险资产组合的CVaR风险关于头寸的敏感度进行了分析,研究了其经济意义。 相似文献
109.
Luiza Amália Moraes Luis Romero Grados 《Journal of Mathematical Analysis and Applications》2003,281(2):575-586
Let Au(BG) be the Banach algebra of all complex valued functions defined on the closed unit ball BG of a complex Banach space G which are uniformly continuous on BG and holomorphic in the interior of BG, endowed with the sup norm. A characterization of the boundaries for Au(BG) is given in case G belongs to a class of Banach spaces that includes the pre-dual of a Lorentz sequence space studied by Gowers in Israel J. Math. 69 (1990) 129-151. The non-existence of the Shilov boundary for Au(BG) is also proved. 相似文献
110.
Heat Kernel Asymptotics of Zaremba Boundary Value Problem 总被引:1,自引:0,他引:1
The Zaremba boundary-value problem is a boundary value problem for Laplace-type second-order partial differential operators
acting on smooth sections of a vector bundle over a smooth compact Riemannian manifold with smooth boundary but with discontinuous
boundary conditions, which include Dirichlet boundary conditions on one part of the boundary and Neumann boundary conditions
on another part of the boundary. We study the heat kernel asymptotics of Zaremba boundary value problem. The construction
of the asymptotic solution of the heat equation is described in detail and the heat kernel is computed explicitly in the leading
approximation. Some of the first nontrivial coefficients of the heat kernel asymptotic expansion are computed explicitly.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献