全文获取类型
收费全文 | 394篇 |
免费 | 415篇 |
国内免费 | 102篇 |
专业分类
化学 | 76篇 |
晶体学 | 224篇 |
力学 | 48篇 |
综合类 | 5篇 |
数学 | 3篇 |
物理学 | 555篇 |
出版年
2024年 | 3篇 |
2023年 | 11篇 |
2022年 | 17篇 |
2021年 | 25篇 |
2020年 | 20篇 |
2019年 | 10篇 |
2018年 | 15篇 |
2017年 | 20篇 |
2016年 | 26篇 |
2015年 | 33篇 |
2014年 | 69篇 |
2013年 | 69篇 |
2012年 | 50篇 |
2011年 | 46篇 |
2010年 | 62篇 |
2009年 | 62篇 |
2008年 | 49篇 |
2007年 | 41篇 |
2006年 | 62篇 |
2005年 | 24篇 |
2004年 | 27篇 |
2003年 | 32篇 |
2002年 | 27篇 |
2001年 | 14篇 |
2000年 | 16篇 |
1999年 | 18篇 |
1998年 | 10篇 |
1997年 | 13篇 |
1996年 | 5篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 8篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 3篇 |
排序方式: 共有911条查询结果,搜索用时 265 毫秒
81.
Electrical Properties of La-Doped Al2O3 Films on Si (100) Substrates as a High-Dielectric-Constant Gate Material
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)
Amorphous La-doped Al2O3 (La: Al2O3) thin films are deposited on n-type (100) Si substrates by rf magnetron co-sputterlng. The composition of the deposited films is measured by energy dispersive x-ray spectroscopy: Capacitance-voltage measurement shows that the dielectric constant k of La-doped Al2O3 films ranges from 8.5 to 11.6 with the increasing La content, and the highest k value of 11.6 is obtained for the 20.14% La content film. In the structure of the Al/La:Al2O3/Si metal oxide semiconductor, the dominant conduction stems from the space- charge-limited current at different temperatures. In addition, the wavelength dependence of the transmittance is studied by ultraviolet spectroscopy and the band gap of all the deposited films is above 5.5eV. The results demonstrate that La-doped Al2O3 can meet the requirement of next-generation gate materials. 相似文献
83.
84.
85.
研究了TiN/SiC纳米多层膜中立方SiC(B1cubic SiC)的形成及其对TiN/SiC多层膜力学性能的影响.结果表明:在TiN/SiC多层膜中,非晶态的SiC层在厚度小于0.6nm时形成立方结构并与TiN形成共格外延生长的超晶格柱状晶,使多层膜产生硬度和弹性模量显著升高的超硬效应,最高硬度超过60GPa.SiC随着层厚的增加转变为非晶相,从而阻止了多层膜的共格外延生长,使薄膜呈现TiN纳米晶和SiC非晶组成的层状结构特征,同时多层膜的硬度和弹性模量下降.TiN/SiC纳米多层膜产生的超硬效应与立方
关键词:
立方碳化硅
TiN/SiC纳米多层膜
外延生长
超硬效应 相似文献
86.
提出了一种具有部分超结(super junction, SJ)结构的新型SiC肖特基二极管,命名为SiC Semi-SJ-SBD结构,通过将常规SBD耐压区分为常规耐压区和超结耐压区来减小导通电阻,改善正向特性.利用二维器件模拟软件MEDICI仿真分析,研究了不同超结深度和厚度时击穿电压(VB)和比导通电阻(Ron-sp),与常规结构的SBD比较得出,半超结结构可以明显改善SiC肖特基二极管特性,并得到优化的设计方案,选择超结宽度2<
关键词:
SiC肖特基二极管
super junction
导通电阻
击穿电压 相似文献
87.
Fabrication and Properties of Double-Side Tl2Ba2CaCu2O8 Thin Film on CeO2 Buffered Sapphire Substrate
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-side Tl2Ba2 CaCu2O8 (Tl-2212) superconducting thin films were fabricated on CeO2 buffered sapphire substrates. The reactive magnetron sputtering technique was used to grow CeO2 buffer thin films on sapphire substrates. Making use of the metal cerium as a sputtering source, the depositing rate is much higher compared with the CeO2 target. The Ti-2212 thin films on CeO2 buffered sapphire substrates were fabricated by adc magnetron sputtering and post-annealing process. The x-ray diffraction indicates that the thin film is pure Tl-2212 phase with the e-axis perpendicular to the substrate surfaces, and epitaxially grown on the CeO2 buffered sapphire. The critical transition temperature Tc is around 106K, the critical current density Jc is around 3.5 MA/cm^2 at 77K, and the microwave surface resistance R8 at 77K and 10 CHz of the film is as low as 390μ Ω. 相似文献
88.
Effect of Different Substrate Temperature on Sb-Doped ZnO Thin Films Prepared by Pulsed Laser Deposition on Sapphire Substrates
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)
Sb-doped ZnO thin films are deposited on c-plane sapphire substrates by pulsed laser deposition. Hall results indicate that the conductivity of the Sb-doped ZnO thin films is strongly dependent on the substrate temperature. The sample deposited at the temperature of 550°C exhibits p-type conductivity. It gives a resistivity of 15.25Ω&#12539;cm, with a Hall mobility of 1.79cm2V-1s-1 and a carrier concentration of 2.290×1017cm-3 at room temperature. The x-ray diffraction indicates that the Sb-doped ZnO thin films deposited in the range of 450-650°C are high c-axis oriented. Low-temperature photoluminescence spectra indicate that the sample deposited at 550°C shows the strong acceptor-bound exciton (A0X) emission. 相似文献
89.
Effect of Interface Nanotexture on Light Extraction of InGaN-Based Green Light Emitting Diodes
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 the enhancement of the light extraction of InGaN-based green light emitting diodes (LEDs) via the interface nanotexturing. The texture consists of high-density nanocraters on the surface of a sapphire substrate with an in situ etching. The width of nanocraters is about 0.5 μm and the depth is around 0.1 μm. It is demonstrated that the LEDs with interface texture exhibit about a 27% improvement in luminance intensity, compared with standard LEDs. High power InGaN-based green LEDs are obtained by using the interface nanotexture. An optical ray-tracing simulation is performed to investigate the effect of interface nanotexture on light extraction. 相似文献
90.
An approach for determining the optical constants of the weakly absorbing substrate is developed and applied to obtain the parameters of CaF2 and fused silica substrates in deep ultraviolet (DUV) and vacuum ultraviolet (VUV) range. A method for extracting the optical constants of thin films deposited on strongly absorbing substrate, which is based on the reflectance spectra measured at different angles of incidence, is also presented. The optical constants are determined by fitting the measured spectra to the theoretical models. The proposed method is applied to determine the refractive index and extinction coefficient (n, k) of MgF2 film deposited on silicon substrate by electron beam evaporation with substrate temperature 300 ℃ and deposition rate 0.2 nm/s. The determined n, k values at 193 nm are 1.433 and 9.1×10-4, respectively. 相似文献