全文获取类型
收费全文 | 727篇 |
免费 | 140篇 |
国内免费 | 98篇 |
专业分类
化学 | 698篇 |
晶体学 | 69篇 |
力学 | 3篇 |
综合类 | 5篇 |
数学 | 1篇 |
物理学 | 189篇 |
出版年
2024年 | 2篇 |
2023年 | 9篇 |
2022年 | 31篇 |
2021年 | 26篇 |
2020年 | 30篇 |
2019年 | 31篇 |
2018年 | 18篇 |
2017年 | 19篇 |
2016年 | 28篇 |
2015年 | 42篇 |
2014年 | 32篇 |
2013年 | 55篇 |
2012年 | 51篇 |
2011年 | 29篇 |
2010年 | 56篇 |
2009年 | 37篇 |
2008年 | 43篇 |
2007年 | 35篇 |
2006年 | 45篇 |
2005年 | 30篇 |
2004年 | 48篇 |
2003年 | 34篇 |
2002年 | 45篇 |
2001年 | 25篇 |
2000年 | 20篇 |
1999年 | 19篇 |
1998年 | 12篇 |
1997年 | 20篇 |
1996年 | 13篇 |
1995年 | 14篇 |
1994年 | 16篇 |
1993年 | 14篇 |
1992年 | 10篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有965条查询结果,搜索用时 15 毫秒
101.
Takeharu Innami Ryushi Fujimura Masahiro Nomura Tsutomu Shimura Kazuo Kuroda 《Optical Review》2005,12(6):448-450
The photorefractive effect was observed in He-ion-implanted semi-insulating GaN film in the UV spectral region. The photorefractive
grating is induced by the electroabsorption effect near the band-edge. Two beam coupling experiments were performed at a wavelength
of 363.8 nm. The experimental results indicate that absorption grating mainly contributes to the beam coupling. 相似文献
102.
F. P. Korshunov A. V. Mudryi A. I. Patuk I. A. Shakin 《Journal of Applied Spectroscopy》1997,64(1):129-131
The processes of defect formation in single crystals of gallium arsenide electron-irradiated at cryogenic temperatures (∼20
K) have been investigated by the luminescence method. It is shown that at such temperatures the primary radiation-induced
defects, in particular, intrinsic interstitial atoms, can migrate in a crystal and form complexes with their participation.
Institute of Solid-State and Semiconductor Physics of the Academy of Sciences of Belarus, 17, P. Brovka St., Minsk, 220072,
Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 122–124, January–February, 1997. 相似文献
103.
Electron impact single and double ionization cross sections of gallium have been calculated in the binary encounter approximation
using accurate expression for σΔ;E including exchange and interference as given by Vriens and Hartree-Fock velocity distributions for the target electrons throughout
the calculations. It is concluded that the ionization of 3d shell contributes partly to single ionization and partly to double
ionization. The results so obtained show reasonably good agreement with the experimental data. 相似文献
104.
105.
Two-color cross-correlation of fs-laser pulses by two-photon induced photoconductivity for near and far field optical measurements 总被引:1,自引:0,他引:1
Wolfgang Schade David L. Osborn Jan Preusser Stephen R. Leone 《Optics Communications》1998,150(1-6):27-32
Two-color two-photon induced photoconductivity in a GaAsP diffusion type photodiode is demonstrated by measuring femtosecond cross-correlation functions for widely separated wavelength pairs of 775 and 1300 nm. Results are obtained for a range of tunable wavelengths and average powers of the incident lasers by measuring the two-photon induced photocurrent as a function of the optical delay between the pulses. The temporal autocorrelation of femtosecond laser pulses in the near-field of a small diameter aluminum coated optical fiber tip is also obtained with the same photodiode method for single colors. 相似文献
106.
为研究使用不同形状光斑触发光导开关对光电导特性的影响,研制了12 mm间隙的半绝缘砷化镓光导开关,在不同的偏置电压下,使用波长为1 064 nm的不同能量的激光触发光导开关并进行了光电导测试。使用了不同形状的光斑(包括面状、线状和点状光斑)触发光导开关并进行了光电导特性的比较,讨论了触发光参数对光导开关特性的影响。对处于开关电极间不同位置的线状光斑触发特性进行了比较,结果显示,本征光电导和非本征光电导情况下光斑位置对光电流的影响正好相反。 相似文献
107.
Microstructure and strain films using in-plane grazing analysis of GaN epitaxial incidence x-ray diffraction
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
This paper investigates the major structural parameters, such as crystal quality and strain state of (001)-oriented GaN thin films grown on sapphire substrates by metalorganic chemical vapour deposition, using an in-plane grazing incidence x-ray diffraction technique. The results are analysed and compared with a complementary out-of-plane x- ray diffraction technique. The twist of the GaN mosaic structure is determined through the direct grazing incidence t of (100) reflection which agrees well with the result obtained by extrapolation method. The method for directly determining the in-plane lattice parameters of the GaN layers is also presented. Combined with the biaxial strain model, it derives the lattice parameters corresponding to fully relaxed GaN films. The GaN epilayers show an increasing residual compressive stress with increasing layer thickness when the two dimensional growth stage is established, reaching to a maximum level of-0.89 GPa. 相似文献
108.
109.
110.
Ksenia Shablinskaya Elena Murashova Zhanafiya Kurenbaeva Alexander Yaroslavtsev Yurii Seropegin Dariusz Kaczorowski 《ChemInform》2013,44(41):no-no
Ce4Ru3Ga3 (I) and La3Ru2Ga2 (II) are synthesized by arc melting of the elements under Ar followed by annealing (873 K, 30 d). 相似文献