全文获取类型
收费全文 | 12417篇 |
免费 | 736篇 |
国内免费 | 746篇 |
专业分类
化学 | 490篇 |
晶体学 | 4篇 |
力学 | 938篇 |
综合类 | 144篇 |
数学 | 10939篇 |
物理学 | 1384篇 |
出版年
2023年 | 102篇 |
2022年 | 105篇 |
2021年 | 147篇 |
2020年 | 212篇 |
2019年 | 262篇 |
2018年 | 241篇 |
2017年 | 274篇 |
2016年 | 299篇 |
2015年 | 238篇 |
2014年 | 410篇 |
2013年 | 902篇 |
2012年 | 505篇 |
2011年 | 511篇 |
2010年 | 445篇 |
2009年 | 671篇 |
2008年 | 734篇 |
2007年 | 737篇 |
2006年 | 675篇 |
2005年 | 590篇 |
2004年 | 532篇 |
2003年 | 520篇 |
2002年 | 622篇 |
2001年 | 415篇 |
2000年 | 483篇 |
1999年 | 367篇 |
1998年 | 436篇 |
1997年 | 355篇 |
1996年 | 245篇 |
1995年 | 191篇 |
1994年 | 196篇 |
1993年 | 157篇 |
1992年 | 152篇 |
1991年 | 127篇 |
1990年 | 121篇 |
1989年 | 85篇 |
1988年 | 72篇 |
1987年 | 66篇 |
1986年 | 82篇 |
1985年 | 75篇 |
1984年 | 72篇 |
1983年 | 35篇 |
1982年 | 60篇 |
1981年 | 58篇 |
1980年 | 61篇 |
1979年 | 57篇 |
1978年 | 46篇 |
1977年 | 45篇 |
1976年 | 41篇 |
1975年 | 14篇 |
1974年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
71.
In this paper, we present a unified treatment and analysis of a dynamic traffic network model with elastic demands formulated and studied as a projected dynamical system. We propose a travel route choice adjustment process that satisfies the projected dynamical system. Under certain conditions, stability and asymptotical stability of the equilibrium patterns are then derived. Finally, two discrete-time algorithms, the Euler method and the Heun method, are proposed for the computation of the solutions, and convergence results established. The convergence results depend crucially on stability analysis. The performance of the algorithms is then illustrated on several transportation networks. 相似文献
72.
HUYUDA MENGZHIQING 《高校应用数学学报(英文版)》1998,13(4):473-477
In this paper, the existence theorem of the cone-weak subdiflerential of set-valued mapping in locally convex topological vector space is proved. 相似文献
73.
Recently, Fishbum and Lavalle (1995) and Lefèvre and Utev (1996) have considered some stochastic order relations specific for arithmetic random variables. The present work is concerned with these orderings, together with two other classes of stochastic order relations closely related. First, attention is paid to characterizations and various properties of all these orderings. Then, sufficient conditions of crossing-type for the two new classes of orderings are derived and extrema among discrete random variables are deduced. This is applied in actuarial sciences to obtain new bounds for the classical single life premiums as well as for the probability of ruin in the compound binomial risk model. 相似文献
74.
沈惠川 《数学物理学报(A辑)》1998,18(1):78-88
将弹性有限变形问题纳入Lagrange力学的理论体系中,并用经典力学中业已存在的Routh方法构建了有限变形平面应变问题和有限变形平面应力问题的基本微分方程,讨论了有限变形大挠度问题vonkarman方程中存在的矛盾进而提出了两种改进方案. 相似文献
75.
A globally convergent Newton method for solving strongly monotone variational inequalities 总被引:14,自引:0,他引:14
Variational inequality problems have been used to formulate and study equilibrium problems, which arise in many fields including economics, operations research and regional sciences. For solving variational inequality problems, various iterative methods such as projection methods and the nonlinear Jacobi method have been developed. These methods are convergent to a solution under certain conditions, but their rates of convergence are typically linear. In this paper we propose to modify the Newton method for variational inequality problems by using a certain differentiable merit function to determine a suitable step length. The purpose of introducing this merit function is to provide some measure of the discrepancy between the solution and the current iterate. It is then shown that, under the strong monotonicity assumption, the method is globally convergent and, under some additional assumptions, the rate of convergence is quadratic. Limited computational experience indicates the high efficiency of the proposed method. 相似文献
76.
本文提出了一类特殊的n人合作对策模型─—弱1—凸对策,研究了弱1—凸对策的解的性质,并证明弱1—凸对策的解满足所有常见的公理化特征. 相似文献
77.
This paper presents an analysis of a portfolio model which can be used to assist a property-liability insurance company in determining the optimal composition of the insurance and investment portfolios. By introducing insurer's threshold risk and relaxing some non-realistic assumptions made in traditional chance constraint insurance and investment portfolio models, we propose a method for an insurer to maximize his return threshold for a given threshold risk level. This proposed model can be used to optimize the composition of underwriting and investment portfolios regarding the insurer's threshold risk level, as well as to generate the efficient frontier by adjusting insurer's threshold risk levels. A numerical example is given based on the industry's aggregated data for a sixteen year period. 相似文献
78.
In this work two non-local problems for the parabolic-hyperbolic type equation with non-characteristic line of changing type
are considered. Unique solvability of these problems is proven. The uniqueness of the solution is proven by the method of
energy integrals and the existence is proven by the method of integral equations. 相似文献
79.
The gedanken experiment of the clock paradox is solved exactly using the general relativistic equations for a static homogeneous gravitational
field. We demonstrate that the general and special relativistic clock paradox solutions are identical and in particular that
they are identical for finite acceleration. Practical expressions are obtained for proper time and coordinate time by using the destination distance as
the key observable parameter. This solution provides a formal demonstration of the identity between the special and general
relativistic clock paradox with finite acceleration and where proper time is assumed to be the same in both formalisms. By
solving the equations of motion for a freely falling clock in a static homogeneous field elapsed times are calculated for
realistic journeys to the stars.
1 Both authors contributed equally to this paper. 相似文献
80.
Browder-Petryshyn 型的严格伪压缩映射的粘滞迭代逼近方法 总被引:1,自引:0,他引:1
主要研究Browder-Petryshyn型的严格伪压缩映射的粘滞迭代逼近过程,证明了Browder-Petryshyn型的严格伪压缩映射的不动点集F(T)是闭凸集.在q-一致光滑且一致凸的Banach空间中,对于严格伪压缩映射T,利用徐洪坤在2004年引进的粘滞迭代得到的序列弱收敛于T的某个不动点.同时证明了Hilbert空间中Browder-Petryshyn型的严格伪压缩映射的相应迭代序列强收敛到T的某个不动点,其结果推广与改进了徐洪坤2004年的相应结果. 相似文献