全文获取类型
收费全文 | 5012篇 |
免费 | 1109篇 |
国内免费 | 2199篇 |
专业分类
化学 | 3956篇 |
晶体学 | 244篇 |
力学 | 224篇 |
综合类 | 257篇 |
数学 | 841篇 |
物理学 | 2798篇 |
出版年
2024年 | 12篇 |
2023年 | 35篇 |
2022年 | 187篇 |
2021年 | 186篇 |
2020年 | 159篇 |
2019年 | 162篇 |
2018年 | 150篇 |
2017年 | 276篇 |
2016年 | 162篇 |
2015年 | 280篇 |
2014年 | 338篇 |
2013年 | 435篇 |
2012年 | 456篇 |
2011年 | 467篇 |
2010年 | 478篇 |
2009年 | 506篇 |
2008年 | 584篇 |
2007年 | 497篇 |
2006年 | 495篇 |
2005年 | 410篇 |
2004年 | 315篇 |
2003年 | 231篇 |
2002年 | 221篇 |
2001年 | 213篇 |
2000年 | 218篇 |
1999年 | 157篇 |
1998年 | 92篇 |
1997年 | 63篇 |
1996年 | 51篇 |
1995年 | 54篇 |
1994年 | 50篇 |
1993年 | 54篇 |
1992年 | 39篇 |
1991年 | 34篇 |
1990年 | 32篇 |
1989年 | 32篇 |
1988年 | 38篇 |
1987年 | 31篇 |
1986年 | 26篇 |
1985年 | 30篇 |
1984年 | 14篇 |
1983年 | 14篇 |
1982年 | 9篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1976年 | 4篇 |
1973年 | 2篇 |
1971年 | 2篇 |
1966年 | 2篇 |
1959年 | 2篇 |
排序方式: 共有8320条查询结果,搜索用时 0 毫秒
901.
Trigger efficiencies at BESⅢ were determined for both the J/ψ and ψ' data taking of 2009. Both dedicated runs and physics datasets are used; efficiencies are presented for Bhabha-scattering events, generic hadronic decay events involving charged tracks, dimuon events and ψ'→π+π-J/ψ, J/ψ→ 1+1- events.The efficiencies are found to lie well above 99% for all relevant physics cases, thus fulfilling the BESⅢ design specifications. 相似文献
902.
Stable Narrow Linewidth 689nm Diode Laser for the Second Stage Cooling and Trapping of Strontium Atoms
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We report stable narrow linewidth laser systems based on self-developed Littman configuration external cavity diode lasers (ECDLs). The frequency of the ECDL is stabilized to a high fineness ultralow-expansion glass reference cavity with the Pound-Drever-Hall technique. By heterodyne beating of two identical systems, we conclude that the linewidth 4.3× 10^-14 at an averaging measurement time. of each ECDL is reduced to lower than 150 Hz and its frequency stability reaches time of 1 s, the averaged long-term frequency drift is less than 0.2 Hz/s over 30 h 相似文献
903.
We investigate the Hopf bifurcations of the recently proposed smooth-and-discontinuous (SD) oscillator which exhibits both smooth and discontinuous dynamics depending on the value of a parameter a. The nonlinearity presented in this system characterizes irrationality and piecewise linearity for smooth and discontinuous cases, respectively, which could not meet the requirements of the conventional methods due to the barrier of Taylor expansion. Introducing a series of new kinds of elliptic integrals of the first and second kind to the perturbed oscillator, we obtain the Poincare-Birchoff normal forms of Hopf bifurcations for both smooth and discontinuous regimes. We also demonstrate the criteria for the occurrence of Hopf bifurcations, the stability of periodic solutions bifurcating from the equilibria and the excellent agreement between the theoretical and numerical results. 相似文献
904.
We propose a scheme to implement an unconventional geometric phase gate in circuit QED, i.e. two superconducting charge qubits inside a superconducting transmission line resonator. The quantum operation depends only on global geometric features, and thus is insensitive to the state of the cavity mode. 相似文献
905.
Mechanical Reinforcement and Piezoelectric Properties of PZT Ceramics Embedded with Nano-Crystalline
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The double-scale lead zirconate titanate (PZT) piezoelectric ceramics were prepared by the solid state processing with PZT nano-crystalline and micro-powder. The microstructures, electrical and mechanical properties of the double-scale PZT are investigated. All the sintered ceramics exhibit a single perovskite structure and the grain size of the dou ble-scale PZT reduces due to the incorporation of PZT nano-crystalline. Compared to normal PZT, the mechanical properties increase significantly and the piezoelectric properties decrease slightly. Mechanisms responsible for the reinforcement of the double-scale PZT are discussed. 相似文献
906.
Dynamic Fracture Toughness and Failure Mechanisms of ZnO Whiskers Secondary Reinforced Composites
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Quasi-static and dynamic fracture properties and damage mechanism of glass fiber polymer composites embeaaea with different mass percentages of ZnO whiskers are investigated by using an Instron Testing machine and a Split- Hopkinson pressure bar. According to the experimental results and linear fracture mechanics, the quasi-static fracture toughness Kic and the dynamic fracture toughness Kid under various impact velocities of specimens are obtained. Fracture mechanism is investigated by fractography analysis with a scanning electron microscope. The experimental results show that the mass percentage of ZnOw has little influence on the quasi-static fracture toughness, but a little influence on the dynamic fracture toughness and time of initial fracture point of specimens by the reason of various fracture mechanisms. 相似文献
907.
The focusing of time reversal acoustic fields for dispersive and multimodal Lamb waves is theoretically investigated and experimentally verified. It is demonstrated that the time reversal Lamb wave signal will reach the maximum amplitude when the observation point is located at the damage location. Based on the time reversal focusing theory, a damage imaging method is proposed for structural health monitoring using Lamb waves. The experiments employ a transducer network consisting of four piezoelectric transducers as actuators and as well sensors for excitation and measurement of Lamb waves. The results show that this method is able to accurately predict damage location and provides an estimation of the possible area even for damage close to one of the transducers or even slightly outside the transducer network. 相似文献
908.
本文利用转移矩阵方法对两种简单的具有吸引尾的势进行了研究.我们发现反射系数在波矢k→0时R=1,反射率与波矢k在k→0时呈线性关系.这说明在发生阱内量子反射时有利于超冷原子生存,因为超冷原子是低速低能原子.此外,我们可以用一个反射时间变化量Δt来判断量子反射的延迟或者超前. 相似文献
909.
用密度泛函B3LYP/6-311++g(d,p)方法对ZnH~(n+)(n=0,1,2)分子离子的势能函数及光谱常数进行了分析,结果表明0价和±1价分子离子都能稳定存在而±2价离子有亚稳定态存在,其基态电子态分别为~2∑(ZnH),~1∑(ZnH~+),~1∑(ZnH~-),~2∑(ZnH~(2+)),~2∑(ZnH~(2-)),其中±2价离子的势能函数曲线明显呈"火山口"型,属于亚稳态分子离子,用八参数Murrell-Sorbie势拟合±2价亚稳态双原子分子离子势能函数得到的拟合曲线与势能扫描点符合得非常好,而四参数Murrell-Sorbie势对±2价离子的拟合与势能扫描点有较大的差距. 相似文献
910.
采用连续可调谐二极管半导体激光器为探测光源,以可调怀特型长光程多通池(46.36~1158.90m)作为吸收池,采用直接吸收的方法,探测了室温下1.65μm附近CH4分子的高分辨率吸收光谱。在6043.00~6053.72cm-1范围内探测了5组不同压力和光程下的吸收光谱,观测到了259条线新的CH4分子吸收谱线,实验数据用Gaussian线型进行拟合,得到了这些吸收谱线的线强、线位置以及线强的标准偏差值,并对光谱中难以分辨的吸收谱线进行了分析。探测得到的最小谱线线强是4.3×10-27cm-1·(molcule·cm-2)-1,吸收谱线线强大于3.0×10-24cm-1·(mol·cm-2)-1由于吸收饱和而未被处理,同时所测得的光谱也显示出CH4分子在1.65μm附近有非常丰富的弱吸收谱线和复杂的结构。文中所报道的吸收谱线都是HITRAN2004数据库中所未报道的,而且也未见有其他文献报道过。 相似文献