全文获取类型
收费全文 | 2860篇 |
免费 | 970篇 |
国内免费 | 261篇 |
专业分类
化学 | 912篇 |
晶体学 | 61篇 |
力学 | 168篇 |
综合类 | 67篇 |
数学 | 151篇 |
物理学 | 2732篇 |
出版年
2024年 | 3篇 |
2023年 | 16篇 |
2022年 | 63篇 |
2021年 | 72篇 |
2020年 | 106篇 |
2019年 | 78篇 |
2018年 | 88篇 |
2017年 | 128篇 |
2016年 | 147篇 |
2015年 | 127篇 |
2014年 | 186篇 |
2013年 | 221篇 |
2012年 | 252篇 |
2011年 | 246篇 |
2010年 | 234篇 |
2009年 | 216篇 |
2008年 | 208篇 |
2007年 | 204篇 |
2006年 | 199篇 |
2005年 | 187篇 |
2004年 | 169篇 |
2003年 | 124篇 |
2002年 | 97篇 |
2001年 | 128篇 |
2000年 | 111篇 |
1999年 | 52篇 |
1998年 | 70篇 |
1997年 | 48篇 |
1996年 | 46篇 |
1995年 | 44篇 |
1994年 | 23篇 |
1993年 | 33篇 |
1992年 | 25篇 |
1991年 | 23篇 |
1990年 | 17篇 |
1989年 | 10篇 |
1988年 | 24篇 |
1987年 | 9篇 |
1986年 | 10篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1974年 | 5篇 |
排序方式: 共有4091条查询结果,搜索用时 0 毫秒
121.
122.
Previous calculations of transport coefficients of particle systems in two or more dimensions have used computer simulations or various approximations, like those implicit in the Boltzmann equation or in the standard probability theory of diffusion. Here an exactly solved model of crystal growth in three dimensions is transformed into a 2D model of steady particle transport. Then the exact, many-body stationary distribution and exact transport coefficients can be found as well as correlation functions. The model is highly asymmetric. In the transverse direction, particles are strongly attracted, so that long transverse rows of particles tend to form at low temperature. Kinks in these rows are rare, so the transverse positions of kinks effectively move continuously on a large distance scale. 相似文献
123.
二极管伏安特性曲线测试电路的改进 总被引:2,自引:0,他引:2
指出了文献中所给出的伏安法测二级管特性曲线电路存在的问题,并给出了改进电路。 相似文献
124.
Yuhei Horio Md. Mijanur Rahman Yurei Imai Yoshihiro Hishikawa Takashi Minemoto 《Current Applied Physics》2017,17(10):1341-1346
The output energy of photovoltaic (PV) modules is influenced by the spectral irradiance distribution of the solar spectrum under outdoor conditions. To rate the precise output energy of PV modules, the correction of short circuit current (ISC) based on actual environmental conditions is needed, because ISC significantly depends on the shape of the spectral irradiance distribution. The average photon energy (APE) is a zero-dimensional index for spectral irradiance distribution, and APE value uniquely describes the shape of a solar spectrum. Thus, APE has an impact on ISC of PV modules. In this contribution, the relationship between APE coefficient and ISC of the multi-crystalline silicon, single-crystalline silicon, heterojunction intrinsic thin-layer, back contact, copper indium selenide and cadmium telluride PV modules has explored. It is revealed that APE value changes the ISC of PV modules which appeared to have immense possibilities of ISC correction using APE coefficient. This new approach can be very effective for precise rating the output energy of PV modules under actual outdoor conditions. 相似文献
125.
Reversal current observed in micro-and submicro-channel flow under non-continuous DC electric field 下载免费PDF全文
In practical applications of biochips and bio-sensors, electrokinetic mechanisms are commonly employed to manipulate and analyze the characteristics of single bio-molecules. To accurately and flexibly control the movement of single molecule within micro-/submicro-fluidic channels, the characteristics of current signals at the initial stage of the flow are systematically studied based on a three-electrode system. The current response of micro-/submicro-fluidic channels filled with different electrolyte solutions in non-continuous external electric field are investigated. It is found, there always exists a current reversal phenomenon, which is an inherent property of the current signals in micro/submicro-fluidics Each solution has an individual critical voltage under which the steady current value is equal to zero The interaction between the steady current and external applied voltage follows an exponential function. All these results can be attributed to the overpotentials of the electric double layer on the electrodes. These results are helpful for the design and fabrication of functional micro/nano-scale fluidic sensors and biochips. 相似文献
126.
Stress-induced leakage current characteristics of PMOS fabricated by a new multi-deposition multi-annealing technique with full gate last process 下载免费PDF全文
In the process of high-k films fabrication, a novel multi deposition multi annealing(MDMA) technique is introduced to replace simple post deposition annealing. The leakage current decreases with the increase of the post deposition annealing(PDA) times. The equivalent oxide thickness(EOT) decreases when the annealing time(s) change from 1 to 2. Furthermore,the characteristics of SILC(stress-induced leakage current) for an ultra-thin SiO_2/HfO_2 gate dielectric stack are studied systematically. The increase of the PDA time(s) from 1 to 2 can decrease the defect and defect generation rate in the HK layer. However, increasing the PDA times to 4 and 7 may introduce too much oxygen, therefore the type of oxygen vacancy changes. 相似文献
127.
128.
129.
Chen-Huan Wu 《Physics letters. A》2019,383(6):550-557
We theoretically investigate the current–current correlation of the two-dimensional (2D) parabolic Dirac system in hexogonal lattice. The analytical expressions of the random phase approximation (RPA) susceptibility, Ruderman–Kittel–Kasuya–Yosida (RKKY) Hamiltonian, and the diamagnetic orbital susceptibility in noninteracting case base on the density–density or current–current correlation function are derived and quantitatively analyzed. In noninteracting case, the dynamical polarization within RPA, and spin transverse susceptibility as well as the RKKY interaction (when close to the half-filling) are related to the current–current response in the 2D parabolic Dirac systems. Both the cases of anisotropic dispersion and isotropic dispersion are discussed. 相似文献
130.
《Physics letters. A》2019,383(27):125855
The nonlinear beam-core evolution equation approach is proposed as a powerful tool to estimate the acceptable beam current in a given circular accelerator. The approach is justified by the macroparticle simulation over a wide beam current parameter region. Space-charge effects on the beam-core evolution are discussed by Poincaré mapping on the beam-core phase space (σ, dσ/ds). The instability seen in the beam-core evolution is rigorously analyzed as an eigenvalue problem in the coupled linear system derived from the linearized beam-core evolution equations. A threshold current resulting in the instability is given by both the nonlinear beam-core evolution equation approach and the coupled linear system approach. As an example, a fast cycling induction synchrotron is evaluated in which the space-charge effects are significant because it is injector-free. 相似文献