全文获取类型
收费全文 | 365篇 |
免费 | 408篇 |
国内免费 | 50篇 |
专业分类
化学 | 23篇 |
晶体学 | 3篇 |
力学 | 24篇 |
综合类 | 10篇 |
数学 | 20篇 |
物理学 | 743篇 |
出版年
2024年 | 5篇 |
2023年 | 12篇 |
2022年 | 9篇 |
2021年 | 5篇 |
2020年 | 6篇 |
2019年 | 8篇 |
2018年 | 8篇 |
2017年 | 11篇 |
2016年 | 15篇 |
2015年 | 38篇 |
2014年 | 50篇 |
2013年 | 35篇 |
2012年 | 28篇 |
2011年 | 30篇 |
2010年 | 56篇 |
2009年 | 56篇 |
2008年 | 62篇 |
2007年 | 44篇 |
2006年 | 35篇 |
2005年 | 40篇 |
2004年 | 42篇 |
2003年 | 52篇 |
2002年 | 28篇 |
2001年 | 15篇 |
2000年 | 14篇 |
1999年 | 13篇 |
1998年 | 12篇 |
1997年 | 5篇 |
1996年 | 13篇 |
1995年 | 14篇 |
1994年 | 16篇 |
1993年 | 8篇 |
1992年 | 8篇 |
1991年 | 13篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1979年 | 1篇 |
排序方式: 共有823条查询结果,搜索用时 31 毫秒
811.
The bound state solutions of the Klein-Gordon equation with the rotating Deng-Fan molecular potential are presented by using a proper approximation to the centrifugal term within the framework of equal scalar and vector Deng-Fan potentials. It is shown that the solutions can be expressed by the generalized hypergeometric functions. The normalized wavefunctions are also derived. 相似文献
812.
YU Jun PAN Wei-Zhen ZHANG Rong-Bo 《理论物理通讯》2009,51(5):865-868
The dynamical behavior of the extended Duffing-Van der Pol oscillator is investigated numerically in detail. With the aid of some numerical simulation tools such as bifurcation diagrams and Poinearé maps, the different routes to chaos and various shapes of strange attractors are observed. To characterize chaotic behavior of this oscillator system, the spectrum of Lyapunov exponent and Lyapunov dimension are also employed. 相似文献
813.
JINShuo XIEBing-Hao ZHANGHong-Biao GEMo-Lin 《理论物理通讯》2004,42(5):681-688
Some analytical solutions of generalized two-mode harmonic oscillators model are obtained by utilizing an algebraic diagonalization method. We find two types of eigenstates which are formulated as extended SU(1,1), SU(2) squeezed number states respectively. Some statistical properties of these states are also discussed. 相似文献
814.
HANYin-Xia LIJing-Hui CHENShi-Gang 《理论物理通讯》2003,40(6):665-668
The transport of a spatially periodic system with infinite globally coupled oscillators driven by temporalspatial noises is investigated. The probability current shows that the correlation of the multiplicative noises with the space, the spatial asymmetry, and the coupling among the different oscillators are ingredients for the transport of particles. It is a new phenomenon that the correlation of the multiplicative noises with the space can induce the nonzero flux. 相似文献
815.
SONGTong-Qiang 《理论物理通讯》2003,40(5):523-526
By taking a unitary transformation approach, we study two harmonic oscillators with both kinetic coupling and coordluate coupling terms, and derive the density matrix of the system. The results show that the ground state of the system is a rotated two single-mode squeezed state. 相似文献
816.
A technical framework of constructing a linear controller for
chaotic synchronization by utilizing the stability theory of
cascade-connected system is presented. Based on the method developed
in the paper, two simple and linear feedback controllers, as
examples, are derived for the synchronization of Liu chaotic system
and Duffing oscillator, respectively. This method is quite flexible
in constructing a control law. Its effectiveness is also illustrated
by the simulation results. 相似文献
817.
The construction of conserved quantities for linearly coupled oscillators and study of symmetries about the conserved quantities 下载免费PDF全文
In this paper, the conserved quantities are constructed using two
methods. The first method is by making an ansatz of the conserved
quantity and then using the definition of Poisson bracket to obtain
the coefficients in the ansatz. The main procedure for the second
method is given as follows. Firstly, the coupled terms in Lagrangian
are eliminated by changing the coordinate scales and rotating the
coordinate axes, secondly, the conserved quantities are obtain in
new coordinate directly, and at last, the conserved quantities are
expressed in the original coordinates by using the inverse transform
of the coordinates. The Noether symmetry and Lie symmetry of the
infinitesimal transformations about the conserved quantities are
also studied in this paper. 相似文献
818.
In this paper, a modified averaging scheme is presented for a class of time-delayed vibration systems with slow variables. The new scheme is a combination of the averaging techniques proposed by Hale and by Lehman and Weibel, respectively. The averaged equation obtained from the modified scheme is simple enough but it retains the required information for the local nonlinear dynamics around an equilibrium. As an application of the present method, the delay value for which a secondary Hopf bifurcation occurs is successfully located for a delayed van der Pol oscillator. 相似文献
819.
针对雪崩光电二极管(Si-APD)所加偏压需要随环境温度作调整,且偏压电路所需的低纹波低噪声等因素,构建了以Royer振荡器和微控制器为核心的偏压电路。该Si-APD偏压电路以BL8032型同步降压控制器作为Royer振荡器的输入电源,以MS5221M型DAC作为该输入电源的调整单元,以AD8606型集成运放和AD7980型ADC作为Royer振荡器输出电压采样单元,以STM32F103TBU6型微控制器作为计算与时序控制单元。本偏压电路不仅具有温度自适应性,而且具有低纹波、低噪声、低功耗和电气安全隔离的特点,能在9~36 VDC宽输入电压范围和-40~70℃环境下良好工作。 相似文献
820.
如何获得频率高、相位噪声低和稳定性高的微波信号一直都是微波光子学领域的研究热点。基于此,提出一种基于受激布里渊散射(SBS)的可调谐光电振荡器(OEO)。实验中光载波和泵浦光来自同一可调谐激光器,利用泵浦光的SBS对光载波的相位调制边带进行放大,通过改变可调谐激光器的输出波长使布里渊频移量发生变化,从而实现输出微波信号的可调谐。实验结果表明,所设计的OEO可以实现频率范围为10.13~10.65 GHz的信号输出,可调谐范围为520 MHz。结构中仅使用了一个相位调制器,无偏压输入器件的引入,这使得所设计的OEO稳定性较高。在20 min内频率漂移小于1 MHz,功率变化小于1.15 dB。 相似文献