全文获取类型
收费全文 | 2438篇 |
免费 | 212篇 |
国内免费 | 184篇 |
专业分类
化学 | 228篇 |
晶体学 | 2篇 |
力学 | 81篇 |
综合类 | 32篇 |
数学 | 1910篇 |
物理学 | 581篇 |
出版年
2024年 | 8篇 |
2023年 | 26篇 |
2022年 | 44篇 |
2021年 | 62篇 |
2020年 | 60篇 |
2019年 | 50篇 |
2018年 | 57篇 |
2017年 | 57篇 |
2016年 | 65篇 |
2015年 | 39篇 |
2014年 | 84篇 |
2013年 | 170篇 |
2012年 | 113篇 |
2011年 | 138篇 |
2010年 | 118篇 |
2009年 | 178篇 |
2008年 | 178篇 |
2007年 | 169篇 |
2006年 | 169篇 |
2005年 | 150篇 |
2004年 | 134篇 |
2003年 | 101篇 |
2002年 | 101篇 |
2001年 | 74篇 |
2000年 | 76篇 |
1999年 | 71篇 |
1998年 | 48篇 |
1997年 | 49篇 |
1996年 | 48篇 |
1995年 | 26篇 |
1994年 | 31篇 |
1993年 | 12篇 |
1992年 | 18篇 |
1991年 | 12篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1988年 | 13篇 |
1987年 | 14篇 |
1986年 | 10篇 |
1985年 | 8篇 |
1984年 | 11篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1973年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有2834条查询结果,搜索用时 31 毫秒
1.
2.
相对论性无自旋粒子在Hartmann势场中运动的精确解 总被引:1,自引:1,他引:0
在标量势等于矢量势的条件下,本文获得了具有Hartmann型势的Klein-Gordon方程的精确解.给出了束缚态的精确的能谱方程和归一化的径向波函数,对于散射态,获得了按“k/2π标度”归一化的径向波函数和相移的解析计算公式.讨论了散射振幅的解析性质和波函数、能谱方程以及相移的非相对论近似. 相似文献
3.
4.
The Boltzmann distribution used in the steady-state analysis of the simulated annealing algorithm gives rise to several scale invariant properties. Scale invariance is first presented in the context of parallel independent processors and then extended to an abstract form based on lumping states together to form new aggregate states. These lumped or aggregate states possess all of the mathematical characteristics, forms and relationships of states (solutions) in the original problem in both first and second moments. These scale invariance properties therefore permit new ways of relating objective function values, conditional expectation values, stationary probabilities, rates of change of stationary probabilities and conditional variances. Such properties therefore provide potential applications in analysis, statistical inference and optimization. Directions for future research that take advantage of scale invariance are also discussed. 相似文献
5.
Many real problems can be modelled as robust shortest path problems on interval digraphs, where intervals represent uncertainty about real costs and a robust path is not too far from the shortest path for each possible configuration of the arc costs.A branch and bound algorithm for this problem is presented. 相似文献
6.
Onofrio Mario Di Vincenzo Plamen Koshlukov Roberto La Scala 《Advances in Applied Mathematics》2006,37(4):541
In this paper we describe completely the involutions of the first kind of the algebra UTn(F) of n×n upper triangular matrices. Every such involution can be extended uniquely to an involution on the full matrix algebra. We describe the equivalence classes of involutions on the upper triangular matrices. There are two distinct classes for UTn(F) when n is even and a single class in the odd case.Furthermore we consider the algebra UT2(F) of the 2×2 upper triangular matrices over an infinite field F of characteristic different from 2. For every involution *, we describe the *-polynomial identities for this algebra. We exhibit bases of the corresponding ideals of identities with involution, and compute the Hilbert (or Poincaré) series and the codimension sequences of the respective relatively free algebras.Then we consider the *-polynomial identities for the algebra UT3(F) over a field of characteristic zero. We describe a finite generating set of the ideal of *-identities for this algebra. These generators are quite a few, and their degrees are relatively large. It seems to us that the problem of describing the *-identities for the algebra UTn(F) of the n×n upper triangular matrices may be much more complicated than in the case of ordinary polynomial identities. 相似文献
7.
Xiangtong Qi 《Discrete Applied Mathematics》2007,155(3):416-422
We study a machine scheduling model in which job scheduling and machine maintenance activities have to be considered simultaneously. We develop the worst-case bounds for some heuristic algorithms, including a sharper worst-case bound of the SPT schedule than the results in the literature, and another bound of the EDD schedule. 相似文献
8.
A. A. Maleev 《Computational Mathematics and Mathematical Physics》2006,46(12):2031-2039
Stationary and nonstationary Jacobi-like iterative processes for solving systems of linear algebraic equations are examined. For a system whose coefficient matrix A is an H-matrix, it is shown that the convergence rate of any Jacobi-like process is at least as high as that of the point Jacobi method as applied to a system with 〈A〉 as the coefficient matrix, where 〈A〉 is a comparison matrix of A. 相似文献
9.
In this paper, we introduce a new concept of semi-preemptive scheduling and we show how it can be used to derive a maximum-flow-based lower bound for the P|rj|Lmax which dominates the well-known preemptive lower bound. We show that, in some cases, the proposed bound strictly dominates the preemptive one while having the same complexity. 相似文献
10.
In this paper, by means of the method of upper and lower solutions and monotone iterative technique, the existence of maximal and minimal solutions of the boundary value problems for first order impulsive delay differential equations is established. 相似文献