全文获取类型
收费全文 | 3441篇 |
免费 | 482篇 |
国内免费 | 280篇 |
专业分类
化学 | 217篇 |
晶体学 | 4篇 |
力学 | 287篇 |
综合类 | 78篇 |
数学 | 3290篇 |
物理学 | 327篇 |
出版年
2024年 | 12篇 |
2023年 | 36篇 |
2022年 | 38篇 |
2021年 | 64篇 |
2020年 | 104篇 |
2019年 | 96篇 |
2018年 | 120篇 |
2017年 | 158篇 |
2016年 | 148篇 |
2015年 | 97篇 |
2014年 | 128篇 |
2013年 | 287篇 |
2012年 | 160篇 |
2011年 | 180篇 |
2010年 | 142篇 |
2009年 | 156篇 |
2008年 | 172篇 |
2007年 | 224篇 |
2006年 | 214篇 |
2005年 | 190篇 |
2004年 | 152篇 |
2003年 | 167篇 |
2002年 | 166篇 |
2001年 | 155篇 |
2000年 | 125篇 |
1999年 | 117篇 |
1998年 | 92篇 |
1997年 | 89篇 |
1996年 | 61篇 |
1995年 | 66篇 |
1994年 | 47篇 |
1993年 | 38篇 |
1992年 | 37篇 |
1991年 | 28篇 |
1990年 | 19篇 |
1989年 | 10篇 |
1988年 | 12篇 |
1987年 | 9篇 |
1986年 | 7篇 |
1985年 | 9篇 |
1984年 | 12篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 16篇 |
1979年 | 8篇 |
1978年 | 3篇 |
1977年 | 7篇 |
1957年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有4203条查询结果,搜索用时 15 毫秒
991.
992.
993.
In this paper, dynamical behavior of a class of neural networks with distributed delays is studied by employing suitable Lyapunov functionals, delay-dependent criteria to ensure local and global asymptotic stability of the equilibrium of the neural networks. Our results are applied to classical Hopfield neural networks with distributed delays and some novel asymptotic stability criteria are also derived. The obtained conditions are shown to be less conservative and restrictive than those reported in the known literature. 相似文献
994.
Propagation modeling of ocean-scattered low-elevation GPS signals for maritime tropospheric duct inversion 下载免费PDF全文
The maritime tropospheric duct is a low-altitude anomalous refractivity structure over the ocean surface,and it can significantly affect the performance of many shore-based/shipboard radar and communication systems.We propose the idea that maritime tropospheric ducts can be retrieved from ocean forward-scattered low-elevation global positioning system(GPS) signals.Retrieval is accomplished by matching the measured power patterns of the signals to those predicted by the forward propagation model as a function of the modified refractivity profile.On the basis of a parabolic equation method and bistatic radar equation,we develop such a forward model for computing the trapped propagation characteristics of an ocean forward-scattered GPS signal within a tropospheric duct.A new GPS scattering initial field is defined for this model to start the propagation modeling.A preliminary test on the performance of this model is conducted using measured data obtained from a 2009-experiment in the South China Sea.Results demonstrate that this model can predict GPS propagation characteristics within maritime tropospheric ducts and serve as a forward model for duct inversion. 相似文献
995.
996.
GLOBAL EXISTENCE AND ASYMPTOTIC BEHAVIOR FOR THE 3D COMPRESSIBLE NON–ISENTROPIC EULER EQUATIONS WITH DAMPING 总被引:1,自引:0,他引:1
We investigate the global existence and asymptotic behavior of classical solutions for the 3D compressible non-isentropic damped Euler equations on a periodic domain. The global existence and uniqueness of classical solutions are obtained when the initial data is near an equilibrium. Furthermore, the exponential convergence rates of the pressure and velocity are also proved by delicate energy methods. 相似文献
997.
关于近似惯性流形及其数值方法的研究 总被引:8,自引:1,他引:8
本文简述了近年来在无穷维动力系统研究中一些数学理论的进展状况,主要目的是结合二维Navier-Stokes方程讨论近似惯性流形及其数值方法的构造和意义. 相似文献
998.
Hawking radiation from cosmological horizon and event horizon of the Reissner-Nordström de Sitter black hole with a global monopole is studied via a new method that was propounded by Robinson and Wilzek and elaborated by Banerjee and Kulkarni. The results show that the gauge current and energy-momentum tensor fluxes, which required keeping gauge covariance and general coordinate invariance at the quantum level in the effective field theory, are exactly equivalent to those of Hawking radiation from the event horizon and the cosmological horizon,
respectively. 相似文献
999.
一类有理交错样条曲线的逼近性及形状修改 总被引:4,自引:3,他引:4
本文提出一类C^2连续的四阶有理交错样条曲线,它能整体或局部逼近于控制多边形。 相似文献
1000.
Damage processes in thermoviscoelastic materials with damage‐dependent thermal expansion coefficients 下载免费PDF全文
Christian Heinemann Elisabetta Rocca 《Mathematical Methods in the Applied Sciences》2015,38(18):4587-4612
In this paper, we prove existence of global in time weak solutions for a highly nonlinear PDE system arising in the context of damage phenomena in thermoviscoelastic materials. The main novelty of the present contribution with respect to the ones already present in the literature consists in the possibility of taking into account a damage‐dependent thermal expansion coefficient. This term implies the presence of nonlinear coupling terms in the PDE system, which make the analysis more challenging. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献