全文获取类型
收费全文 | 10736篇 |
免费 | 381篇 |
国内免费 | 489篇 |
专业分类
化学 | 693篇 |
晶体学 | 42篇 |
力学 | 782篇 |
综合类 | 51篇 |
数学 | 7529篇 |
物理学 | 2509篇 |
出版年
2024年 | 15篇 |
2023年 | 104篇 |
2022年 | 117篇 |
2021年 | 158篇 |
2020年 | 193篇 |
2019年 | 209篇 |
2018年 | 204篇 |
2017年 | 220篇 |
2016年 | 241篇 |
2015年 | 222篇 |
2014年 | 531篇 |
2013年 | 940篇 |
2012年 | 479篇 |
2011年 | 701篇 |
2010年 | 570篇 |
2009年 | 688篇 |
2008年 | 738篇 |
2007年 | 756篇 |
2006年 | 490篇 |
2005年 | 389篇 |
2004年 | 342篇 |
2003年 | 353篇 |
2002年 | 308篇 |
2001年 | 266篇 |
2000年 | 279篇 |
1999年 | 273篇 |
1998年 | 222篇 |
1997年 | 210篇 |
1996年 | 174篇 |
1995年 | 180篇 |
1994年 | 154篇 |
1993年 | 89篇 |
1992年 | 78篇 |
1991年 | 67篇 |
1990年 | 54篇 |
1989年 | 44篇 |
1988年 | 40篇 |
1987年 | 38篇 |
1986年 | 48篇 |
1985年 | 64篇 |
1984年 | 49篇 |
1983年 | 41篇 |
1982年 | 41篇 |
1981年 | 33篇 |
1980年 | 44篇 |
1979年 | 54篇 |
1978年 | 29篇 |
1977年 | 34篇 |
1976年 | 13篇 |
1975年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Noureddine Igbida 《Journal of Mathematical Analysis and Applications》2007,335(2):1061-1078
In this paper, we study the nonlinear evolution equation of Hele-Shaw type with dynamical boundary conditions. That is, the equation ut=Δw+f where u∈H(w) and H is the Heaviside function, with boundary condition μ(x,w)t∂w+k∇w⋅ν=g, where ν denotes the outward normal vector of the fixed boundary of the domain. We prove existence, uniqueness and some qualitative properties of the solution. 相似文献
72.
In this paper we consider a class of nonlinear delay partial difference equations and a class of linear delay partial difference equations with variable coefficients, which may change sign. We obtain oscillation criteria for these equations. There are no results for the oscillation of these equations up to now. 相似文献
73.
Jonathan M. Borwein 《Optimization Letters》2007,1(1):21-32
This paper is a companion to a lecture given at the Prague Spring School in Analysis in April 2006. It highlights four distinct variational methods of proving that a finite dimensional Chebyshev set is convex and hopes to inspire renewed work on the open question of whether every Chebyshev set in Hilbert space is convex. 相似文献
74.
75.
Rolando Cavazos-Cadena 《Annals of Operations Research》1991,28(1):169-184
We consider a class of Markov decision processes withfinite state and action spaces which, essentially, is determined by the following condition: The state space isirreducible under the action of any stationary policy. However, except by this restriction, the transition law iscompletely unknown to the controller. In this context, we find a set of policies under which thefrequency estimators of the transition law are strongly consistent and then, this result is applied to constructadaptive asymptotically discount-optimal policies.Dedicated to Professor Truman O. Lewis, on the occasion of his sixtieth birthdayThis research was supported in part by the Third World Academy of Sciences (TWAS) under Grant TWAS RG MP 898-152, and in part by the Consejo Nacional de Ciencia y Tecnología (CONACYT) under Grant A128CCOEO550 (MT-2). 相似文献
76.
A. BOURHIM 《数学年刊B辑(英文版)》2004,25(3):369-382
In this note, the local spectral properties of unilateral operator weighted shifts arestudied. 相似文献
77.
Discrete global descent method for discrete global optimization and nonlinear integer programming 总被引:2,自引:0,他引:2
A novel method, entitled the discrete global descent method, is developed in this paper to solve discrete global optimization
problems and nonlinear integer programming problems. This method moves from one discrete minimizer of the objective function
f to another better one at each iteration with the help of an auxiliary function, entitled the discrete global descent function.
The discrete global descent function guarantees that its discrete minimizers coincide with the better discrete minimizers
of f under some standard assumptions. This property also ensures that a better discrete minimizer of f can be found by some classical local search methods. Numerical experiments on several test problems with up to 100 integer
variables and up to 1.38 × 10104 feasible points have demonstrated the applicability and efficiency of the proposed method. 相似文献
78.
本文在经典风险模型的基础上,将索赔到达过程推广为更新过程,索赔可以批量到达,且带有常数利息力和Brown运动干扰项,得到一个新的风险模型,运用Markov骨架过程的方法,得出盈余过程的瞬时分布和生存概率. 相似文献
79.
This paper discusses a class of second-order derivative nonlinear Schrödinger equations which are used to describe the upper-hybrid oscillation propagation. By establishing a variational problem, applying the potential well argument and the concavity method, we prove that there exists a sharp condition for global existence and blow-up of the solutions to the nonlinear Schrödinger equation. In addition, we also answer the question: how small are the initial data, the global solutions exist? 相似文献
80.
A model proposed in the literature for fish schools of relatively large size is studied for mathematical and qualitative properties. Existence, uniqueness and positivity of solutions are established and bifurcation properties relative to diffusion and alignment parameters are studied. 相似文献