全文获取类型
收费全文 | 4889篇 |
免费 | 1139篇 |
国内免费 | 1715篇 |
专业分类
化学 | 3407篇 |
晶体学 | 228篇 |
力学 | 313篇 |
综合类 | 169篇 |
数学 | 762篇 |
物理学 | 2864篇 |
出版年
2024年 | 6篇 |
2023年 | 41篇 |
2022年 | 181篇 |
2021年 | 142篇 |
2020年 | 150篇 |
2019年 | 160篇 |
2018年 | 160篇 |
2017年 | 236篇 |
2016年 | 167篇 |
2015年 | 241篇 |
2014年 | 297篇 |
2013年 | 443篇 |
2012年 | 399篇 |
2011年 | 431篇 |
2010年 | 468篇 |
2009年 | 449篇 |
2008年 | 530篇 |
2007年 | 447篇 |
2006年 | 463篇 |
2005年 | 374篇 |
2004年 | 302篇 |
2003年 | 207篇 |
2002年 | 214篇 |
2001年 | 204篇 |
2000年 | 205篇 |
1999年 | 107篇 |
1998年 | 56篇 |
1997年 | 54篇 |
1996年 | 39篇 |
1995年 | 43篇 |
1994年 | 53篇 |
1993年 | 48篇 |
1992年 | 68篇 |
1991年 | 51篇 |
1990年 | 42篇 |
1989年 | 53篇 |
1988年 | 33篇 |
1987年 | 32篇 |
1986年 | 23篇 |
1985年 | 12篇 |
1984年 | 15篇 |
1983年 | 14篇 |
1982年 | 14篇 |
1981年 | 19篇 |
1980年 | 15篇 |
1979年 | 10篇 |
1978年 | 9篇 |
1977年 | 4篇 |
1965年 | 6篇 |
1963年 | 2篇 |
排序方式: 共有7743条查询结果,搜索用时 15 毫秒
871.
872.
The optically stimulated luminescent (OSL) radiation dosimeter technically surveys a wide dynamic measurement range and a high sensitivity. Optical fiber dosimeters provide capability for remote monitoring of the radiation in the locations which are difficult-to-access and hazardous. In addition, optical fiber dosimeters are immune to electrical and radio-frequency interference. In this paper, a novel remote optical fiber radiation dosimeter is described. The optical fiber dosimeter takes advantage of the charge trapping materials CaS:Ce, Sm that exhibit OSL. The measuring range of the dosimeter is from 0.1 to 100 Gy. 相似文献
873.
For the first time we introduce an operator Δ
h
(γ,ε;κ) for studying Husimi distribution function in phase space (γ,ε) for electron’s states in uniform magnetic field, where κ is the Gaussian spatial width parameter. The marginal distributions of the Husimi function are Gaussian-broadened version
of the Wigner marginal distributions. Using the Wigner operator in the entangled state 〈λ
| representation we find that Δ
h
(γ,ε;κ) is just a pure squeezed coherent state density operator |
γ,ε〉
κ
κ
〈γ,ε
|, which brings much convenience for studying Husimi distribution, so we name Δ
h
(γ,ε;κ) the Husimi operator. We then derive Husimi operator’s normally ordered form that provides us with an operator version to
examine various properties of the Husimi distribution.
Work supported by the National Natural Science Foundation under the grant: 10775097. 相似文献
874.
An alternative protocol is proposed to implement three-qubit phase gate between photon and atoms in a high-Q bimodel optical cavity. The idea can be extended to directly implement N-qubit phase gate, and the gating time that is required to implement the protocol does not rise with increasing number of qubits. The influence of cavity decay and atomic spontaneous emission on the gate fidelity is also discussed. 相似文献
875.
Number-Phase Quantization and Deriving Energy-Level Gap of Two LC Circuits with Mutual-Inductance
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)
For two LC circuits with mutual-inductance, we introduce a new quantization scheme in the context of number- phase quantization through the standard Lagrangian formalism. The commutative relation between the charge operator and the magnetic flux operator is derived. Then we use the Heisenberg equation of motion to obtain the current and voltage equation across the inductance and capacity. The results clearly show how the current and voltage in a single LC circuit are affected by the circuit parameters and inductance coupling coettlcient. In addition, adopting invariant eigen-operator method the energy-level gap of the dynamic Hamiltonian which describes two LC circuits with mutual-inductance is obtained. 相似文献
876.
Influence of Different Substrates on Laser Induced Damage Thresholds at 1064nm of Ta2O5 Films
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)
Ta2O5 films are prepared on Si, BK7, fused silica, antireflection (AR) and high reflector (HR) substrates by electron beam evaporation method, respectively. Both the optical property and laser induced damage thresholds (LIDTs) at 1064 nm of Ta2O5 films on different substrates are investigated before and after annealing at 673 K for 12 h. It is shown that annealing increases the refractive index and decreases the extinction index, and improves the O/Ta ratio of the Ta2O5 films from 2.42 to 2.50. Moreover, the results show that the LIDTs of the Ta2O5 films are mainly correlated with three parameters: substrate property, substoichiometry defect in the films and impurity defect at the interface between the substrate and the films. Details of the laser induced damage models in different cases are discussed. 相似文献
877.
We propose a decoy state quantum key distribution scheme with odd coherent state which follows sub-Poissonian distributed photon count and has low probability of the multi-photon event and vacuum event in each pulse. The numerical calculations show that our scheme can improve efficiently the key generation rate and secure communication distance. Fhrthermore, only one decoy state is necessary to approach to the perfect asymptotic limit with infinite decoy states in our scheme, but at least two decoy states are needed in other scheme. 相似文献
878.
We consider the fluctuation of mesoscopic RLC circuit at finite temperature since a resistance always produces Joule heat when the circuit is working. By virtue of the thermo field dynamics and the coherent thermo state representation we show that the quantum mechanical zero-point fluctuations of both charge and current increase with the rising temperature and the resistance value. 相似文献
879.
Formation Mechanisms of Electrical Conductivity and Optical Properties of ZnO:N Film Produced by Annealing Treatment
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)
WANG Xiang-Hu YAO Bin WEI Zhi-Peng SHEN De-Zhen ZHANG Zhen-Zhong LU You-Ming ZHANG Ji-Ying FAN Xi-Wu 《中国物理快报》2008,25(8):2993-2996
The effects of annealing on the chemical states of N dopant, electrical, and optical properties of N-doped ZnO film grown by molecular beam epitaxy (MBE) are investigated. Both the as-grown ZnO:N film and the film annealed in N2 are of n-type conductivity, whereas the conductivity converts into p-type conductivity for the film annealed in O2. We suggest that the transformation of conductivity is ascribed to the change in ratio of the N molecular number on O site (N2)O to the N atom number on O site (NO) in ZnO:N films under the various annealed atmosphere. For the ZnO:N film annealed in N2, the percentage content of (N2)O is larger than that of NO, i.e.the ratio >1, resulting in the n-type conductivity. However, in the case of the ZnO:N film annealed in O2, the percentage content of (N2)O is fewer than that of NO, i.e., the ratio <1, giving rise to the p-type conductivity. There is an obvious difference between low-temperature (80K) PL spectra of ZnO:N film annealed in N2 and that of ZnO:N film annealed in O2. An emission band located at 3.358eV is observed in the spectra of the ZnO:N film after annealed in N2, this emission band is due to donor-bound exciton (D0X). After annealed in O2, the PL of the donor-bound exciton disappeared, an emission band located at 3.348eV is observed, this emission band is assigned to acceptor-bound exciton (A0X). 相似文献
880.
A Simple Route of Morphology Control and Structural and Optical Properties of ZnO Grown by Metal-Organic Chemical Vapour Deposition
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)
Employing the metal-organic chemical vapour deposition (MOCVD) technique, we prepare ZnO samples with different morphologies from the film to nanorods through conveniently changing the bubbled diethylzinc flux (BDF) and the carrier gas flux of oxygen (OCGF). The scanning electron microscope images indicate that small BDF and OCGF induce two-dimensional growth while the large ones avail quasi-one-dimensional growth. X-ray diffraction (XRD) and Raman scattering analyses show that all of the morphology-dependent ZnO samples are of high crystal quality with a c-axis orientation. From the precise shifts of the 20 locations of ZnQ (002) face in the XRD patterns and the E2 (high) locations in the Raman spectra, we deduce that the compressive stress forms in the ZnO samples and is strengthened with the increasing BDF and OCGF. Photoluminescence spectroscopy results show all the samples have a sharp ultraviolet luminescent band without any defects-related emission. Upon the experiments a possible growth mechanism is proposed. 相似文献