全文获取类型
收费全文 | 3550篇 |
免费 | 376篇 |
国内免费 | 307篇 |
专业分类
化学 | 1351篇 |
晶体学 | 18篇 |
力学 | 131篇 |
综合类 | 53篇 |
数学 | 2294篇 |
物理学 | 386篇 |
出版年
2024年 | 10篇 |
2023年 | 44篇 |
2022年 | 48篇 |
2021年 | 69篇 |
2020年 | 95篇 |
2019年 | 95篇 |
2018年 | 92篇 |
2017年 | 124篇 |
2016年 | 138篇 |
2015年 | 82篇 |
2014年 | 149篇 |
2013年 | 347篇 |
2012年 | 226篇 |
2011年 | 194篇 |
2010年 | 179篇 |
2009年 | 219篇 |
2008年 | 218篇 |
2007年 | 206篇 |
2006年 | 223篇 |
2005年 | 170篇 |
2004年 | 145篇 |
2003年 | 158篇 |
2002年 | 148篇 |
2001年 | 111篇 |
2000年 | 108篇 |
1999年 | 88篇 |
1998年 | 82篇 |
1997年 | 67篇 |
1996年 | 46篇 |
1995年 | 43篇 |
1994年 | 47篇 |
1993年 | 34篇 |
1992年 | 24篇 |
1991年 | 20篇 |
1990年 | 22篇 |
1989年 | 20篇 |
1988年 | 16篇 |
1987年 | 15篇 |
1986年 | 11篇 |
1985年 | 21篇 |
1984年 | 17篇 |
1983年 | 7篇 |
1982年 | 10篇 |
1981年 | 9篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1975年 | 5篇 |
1936年 | 3篇 |
排序方式: 共有4233条查询结果,搜索用时 15 毫秒
1.
2.
In this paper, the authors studied certain properties of the estimate of Liang and Krishnaiah (1985, J. Multivariate Anal. 16, 162–172) for multivariate binary density. An alternative shrinkage estimate is also obtained. The above results are generalized to general orthonormal systems. 相似文献
3.
The large deviation principle (LDP) which has been effectively used in queueing analysis is the sample path LDP, the LDP in a function space endowed with the uniform topology. Chang [5] has shown that in the discrete-time G/D/1 queueing system under the FIFO discipline, the departure process satisfies the sample path LDP if so does the arrival process. In this paper, we consider arrival processes satisfying the LDP in a space of measures endowed with the weak* topology (Lynch and Sethuraman [12]) which holds under a weaker condition. It is shown that in the queueing system mentioned above, the departure processes still satisfies the sample path LDP. Our result thus covers arrival processes which can be ruled out in the work of Chang [5]. The result is then applied to obtain the exponential decay rate of the queue length probability in an intree network as was obtained by Chang [5], who considered the arrival process satisfying the sample path LDP. 相似文献
4.
孙文祥 《中国科学A辑(英文版)》2002,45(9):1147-1153
A Liao hyperbolic diffeomorphism has equal measure entropy and topological entropy to that of its induced systems on frame
bundles and Grassmann bundles. This solves a problem Liao posed in 1996 for Liao hyperbolic diffeomorphisms. 相似文献
5.
NEW WAVELET BASES FOR NON-HOMOGENEOUS SYMBOLIC SPACE OpS1,1^m AND RELATED KERNEL-DISTRIBUTION SPACES
YANG Qixiang 《数学年刊B辑(英文版)》2002,23(4):551-562
This paper constructs several classes of new wavelet bases, which are unconditional bases for related operator spaces. Using these bases, the author analyzes non-homogeneous symbolic space OpSm1,1 and two related kernel-distribution spaces, and characterizes them in two wavelet coefficients spaces. Besides, some properties for singular integral operators are studied. 相似文献
6.
By using the quasi-Lyapunov function, some sufficient conditions of global exponential stability for impulsive systems are established, which is the basis for the following discussion. Then, by employing Riccati inequality and Hamilton-Jacobi inequality approach, some sufficient conditions of robust exponential stability for uncertain linear/nonlinear impulsive systems are derived, respectively. Finally, some examples are given to illustrate the applications of the theory. 相似文献
7.
TANG Chen ZHANG Fang YAN Hai-Qing CHEN Zhan-Qing LUO Tao 《理论物理通讯》2005,44(3):435-439
We develop the three-step explicit and implicit schemes of exponential fitting methods. We use the three- step explicit exponential fitting scheme to predict an approximation, then use the three-step implicit exponential fitting scheme to correct this prediction. This combination is called the three-step predictor-corrector of exponential fitting method. The three-step predictor-corrector of exponential fitting method is applied to numerically compute the coupled nonlinear Schroedinger equation and the nonlinear Schroedinger equation with varying coefficients. The numerical results show that the scheme is highly accurate. 相似文献
8.
A new prediction technique is proposed for chaotic time series. The usefulness of the technique is thatit can kick off some false neighbor points which are not suitable for the local estimation of the dynamics systems. Atime-delayed embedding is used to reconstruct the underlying attractor, and the prediction model is based on the timeevolution of the topological neighboring in the phase space. We use a feedforward neural network to approximate thelocal dominant Lyapunov exponent, and choose the spatial neighbors by the Lyapunov exponent. The model is testedfor the Mackey-Glass equation and the convection amplitude of lorenz systems. The results indicate that this predictiontechnique can improve the prediction of chaotic time series. 相似文献
9.
一类非线性微分方程的脉冲镇定 总被引:5,自引:0,他引:5
针对一般形式的常微分系统提出了脉冲指数镇定的概念,具体研究了一类分离变量型非线性常微分方程的脉冲镇定问题,得到了该方程可脉冲指数镇定的充分判据,全文的概念及结论突出了脉冲在方程稳定性方面的控制效果。 相似文献
10.
In this paper we consider the numerical approximation of steady and unsteady generalized Newtonian fluid flows using divergence free finite elements generated by the Powell–Sabin–Heindl elements. We derive a priori and a posteriori finite element error estimates and prove convergence of the method of successive approximations for the steady flow case. A priori error estimates of unsteady flows are also considered. These results provide a theoretical foundation and supporting numerical studies are to be provided in Part II. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献