全文获取类型
收费全文 | 2906篇 |
免费 | 1369篇 |
国内免费 | 127篇 |
专业分类
化学 | 233篇 |
晶体学 | 6篇 |
力学 | 517篇 |
综合类 | 122篇 |
数学 | 633篇 |
物理学 | 2891篇 |
出版年
2024年 | 2篇 |
2023年 | 15篇 |
2022年 | 68篇 |
2021年 | 78篇 |
2020年 | 74篇 |
2019年 | 45篇 |
2018年 | 57篇 |
2017年 | 94篇 |
2016年 | 124篇 |
2015年 | 101篇 |
2014年 | 197篇 |
2013年 | 209篇 |
2012年 | 234篇 |
2011年 | 227篇 |
2010年 | 228篇 |
2009年 | 203篇 |
2008年 | 257篇 |
2007年 | 256篇 |
2006年 | 260篇 |
2005年 | 220篇 |
2004年 | 138篇 |
2003年 | 193篇 |
2002年 | 168篇 |
2001年 | 184篇 |
2000年 | 113篇 |
1999年 | 94篇 |
1998年 | 99篇 |
1997年 | 87篇 |
1996年 | 52篇 |
1995年 | 54篇 |
1994年 | 40篇 |
1993年 | 32篇 |
1992年 | 41篇 |
1991年 | 30篇 |
1990年 | 28篇 |
1989年 | 19篇 |
1988年 | 12篇 |
1987年 | 17篇 |
1986年 | 14篇 |
1985年 | 14篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1957年 | 2篇 |
排序方式: 共有4402条查询结果,搜索用时 15 毫秒
991.
992.
ZHAO Wen-Lei JIE Quan-Lin 《理论物理通讯》2009,51(3):465-469
We investigate the quantum-classical transition in a system of two coupled kicked rotors. We lind that when the mass of one kicked rotor is much smaller than the other's, the influence of the light kicked rotor is still able to make decoherence of the heavy one. This leads to the quantum-classical transition of the heavy kicked rotor. We demonstrate this by two different coupling potentials. 相似文献
993.
用线性霍耳集成电路测量螺线管中磁场分布 总被引:1,自引:0,他引:1
本文介绍了一种霍耳集成传感器的特性及测磁场方法 ,并给出了测量长直螺线管内磁场的实验结果 相似文献
994.
基于混沌粒子群优化算法的灰色GM(1,1)模型在地下水埋深预测中的应用 总被引:2,自引:0,他引:2
将混沌优化算法与粒子群优化算法相结合,形成新的混沌粒子群优化算法.利用混沌运动的遍历性,避免陷入局部最优.同时,粒子群算法能加快混沌优化算法的收敛速度,使搜索效率得到提高.用混沌粒子群优化算法优化灰色GM(1,1)模型中的参数,通过横向和纵向比较,优化效果良好,模型预测精度得到了提高.运用该模型对三江平原地下水埋深进行动态预测,预测结果可为有关决策部门提供参考. 相似文献
995.
996.
T. Taniguchi G. P. Morriss 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,50(1-2):305-309
The relation between the Lyapunov modes (delocalized
Lyapunov vectors) and the momentum autocorrelation function
is discussed in two-dimensional hard-disk systems.
We show numerical evidence that
the smallest time-oscillating period of the Lyapunov modes
is twice as long as the time-oscillating period of
momentum autocorrelation function for
both square and rectangular two-dimensional systems
with hard-wall boundary conditions. 相似文献
997.
Xiqu Chen Xinjian Yi Ying Yang Yi Li 《International Journal of Infrared and Millimeter Waves》2006,27(9):1281-1291
A new CMOS readout circuit for VO2-based uncooled FPAs is presented in this paper. The on-chip readout circuit consists of three major parts: An input circuit
of BCDI structure, a column-shared integration circuit of CTIA structure, and a common CDS output circuit. The simple configuration
of the input circuit makes it possible to operate more circuits in parallel, and increases the integration time and number
of pixels, the column-shared integration circuit which is suitable for small pixel size provides low noise, high gain, a highly
stable detector bias, and high photon current injection efficiency, and the common CDS output circuit is utilized to reduce
or eliminate low-frequency noise of the readout circuit. An experimental readout chip for 50-μm-pitch 32×32 element VO2-based uncooled FPAs has been fabricated. The measurement results of the fabricated readout chip have successfully verified
its readout function and excellent performance. 相似文献
998.
JI Ying-Hua 《理论物理通讯》2008,50(10):897-902
Taking into account the interaction between electrons and phonons, in the case without-rotating-wave aproximation, we study the entangling property between the mesoscopic circuit and environment at coherent state or equilibrium state. The result indicates that, in long time limit t →∞, the averages of charge and current in the circuit only depend on the average of the system at the initial state when the environment is initially at thermal equilibrimn. However, when the environment is initially at coherent state, the average of charge and current in the circuit is determined by the specific coherent state ensemble. Generally speaking, the entanglement between the circuit and environment will lead to the quantum state purity declining of the circuit, then the circuit emerges decoherent phenomenon, and so a mixed sta.te appears. Purity changes are related to the initial quantum state of environment and circuit. With the further evolution of time, coherence will be gradually restored, but cannot return to 1. 相似文献
999.
《Physics letters. A》2019,383(25):3080-3087
1000.
The aim of this work is to elaborate the LiNaWO4 compound, using the solid state method, then to characterize it using an XR study which confirms that it crystallizes in the orthorhombic system with P222 as space group and with the lattice parameters a = 12.82 Å, b = 17.49 Å, c = 7.25 Å and α = β = γ = 90°. The differential scanning calorimetry (DSC) shows two endothermic peaks at T1 = 388 K and T2 = 500 K. The first peak is detected by the dielectric study, attributed to a phase transition from a ferroelectric phase to a paraelectric one, while the second peak indicates the presence of a phase transition, confirmed later by the result of the electrical study. All modes pertaining to vibrations of WO42? tetrahedral appear in the Raman spectrum. Moreover, its impedance response is modeled by a single cell formed by a parallel combination of R//C//CPE, i.e. the response of our compound is that of the grain. The variation of the σg and σdc, as a function of temperature, confirms the phase transition observed in the calorimetric study at T2. The conduction mechanism in the two phases indicates that the first phase (I) is described by the CBH model and the second phase by the OLPT model. 相似文献