全文获取类型
收费全文 | 434篇 |
免费 | 39篇 |
国内免费 | 16篇 |
专业分类
电工技术 | 9篇 |
综合类 | 7篇 |
化学工业 | 84篇 |
金属工艺 | 102篇 |
机械仪表 | 25篇 |
建筑科学 | 2篇 |
矿业工程 | 1篇 |
能源动力 | 11篇 |
轻工业 | 2篇 |
石油天然气 | 1篇 |
武器工业 | 2篇 |
无线电 | 54篇 |
一般工业技术 | 179篇 |
冶金工业 | 5篇 |
原子能技术 | 4篇 |
自动化技术 | 1篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 2篇 |
2021年 | 6篇 |
2020年 | 12篇 |
2019年 | 9篇 |
2018年 | 12篇 |
2017年 | 19篇 |
2016年 | 14篇 |
2015年 | 23篇 |
2014年 | 21篇 |
2013年 | 17篇 |
2012年 | 24篇 |
2011年 | 43篇 |
2010年 | 32篇 |
2009年 | 28篇 |
2008年 | 27篇 |
2007年 | 31篇 |
2006年 | 16篇 |
2005年 | 19篇 |
2004年 | 18篇 |
2003年 | 19篇 |
2002年 | 14篇 |
2001年 | 15篇 |
2000年 | 6篇 |
1999年 | 11篇 |
1998年 | 15篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1989年 | 5篇 |
1986年 | 1篇 |
1985年 | 2篇 |
排序方式: 共有489条查询结果,搜索用时 15 毫秒
81.
Structure, hardness and thermal stability of TiAlN and nanolayered TiAlN/CrN multilayer films 总被引:1,自引:0,他引:1
TiAlN films were deposited on silicon (1 1 1) substrates from a TiAl target using a reactive DC magnetron sputtering process in Ar+N2 plasma. Films were prepared at various nitrogen flow rates and TiAl target compositions. Similarly, CrN films were prepared from the reactive sputtering of Cr target. Subsequently, nanolayered TiAlN/CrN multilayer films were deposited at various modulation wavelengths (Λ). X-ray diffraction (XRD), energy dispersive X-ray analysis, nanoindentation and atomic force microscopy were used to characterize the films. The XRD confirmed the formation of superlattice structure at low modulation wavelengths. The maximum hardness of TiAlN/CrN multilayers was 3900 kg/mm2, whereas TiAlN and CrN films exhibited maximum hardnesses of 3850 and 1000 kg/mm2, respectively. Thermal stability of TiAlN and TiAlN/CrN multilayer films was studied by heating the films in air in the temperature range (TA) of 500-900 °C for 30 min. The XRD spectra revealed that TiAlN/CrN multilayers were stable up to 800 °C and got oxidized substantially at 900 °C. On the other hand, the TiAlN films were stable up to 700 °C and got completely oxidized at 800 °C. Nanoindentation measurements performed on the films after heat treatment showed that TiAlN retained a hardness of 2200 kg/mm2 at TA=700 °C and TiAlN/CrN multilayers retained hardness as high as 2600 kg/mm2 upon annealing at 800° C. 相似文献
82.
83.
为了研究纳米多层薄膜的超硬效应 ,采用反应溅射法制备从 1 4nm至 2 7nm不同调制周期的一系列TiN/NbN纳米多层膜。高分辨电子显微镜对薄膜的调制结构和界面生长方式的观察发现 ,TiN/NbN膜具有很好的调制结构 ,并呈现以面心立方晶体结构穿过调制界面外延生长的多晶超晶格结构特征。显微硬度测量表明 ,TiN/NbN纳米多层膜存在随调制周期变化的超硬效应。薄膜在调制周期为 8 3nm时达到HK39 0GPa的最高硬度。分析认为 ,两种不同晶格常数的晶体外延生长形成的交变应力场 ,对材料有强化作用 ,这是TiN/NbN纳米多层膜产生超硬效应的主要原因 相似文献
84.
85.
采用单槽控电位双脉冲技术在n-Si(111)晶面上制备了[Ni80Fe20/Cu]n多层膜,用SEM观测了多层膜的断面形貌,利用X射线衍射(XRD)表征了多层膜的超晶格结构。采用四探针法研究了多层膜的巨磁电阻(GMR)性能,结果表明,多层膜的GMR值随着Cu层厚度的变化发生周期性振荡,随着NiFe层厚度的增加先增大后减小;当样品结构为[NiFe(1.6 nm)/Cu(2.6 nm)]80时,GMR值可达6.4%;多层膜的最低饱和磁场仅为750Oe。磁滞回线测试结果表明,反铁磁耦合多层膜具有较小的矩形比,更适宜作为磁头材料。 相似文献
86.
In the present study, multilayered Cr–N/Cr–Al–N coatings were prepared by cathodic arc physical vapor deposition (PVD) with different numbers of layers and the same total thickness on AISI 630 steel in an attempt to improve the wear and erosion–corrosion resistance. Structural analysis of the coatings was performed by field scanning electron microscopy, X-ray diffraction (XRD), and energy-dispersive spectroscopy. Depth profiles and roughness parameters of worn surfaces were calculated after erosion and wear tests. XRD indicated that nitride compounds were formed in multilayer coatings by PVD. The Cr–N/Cr–Al–N coating exhibited superior corrosion resistance compared with AISI 630 substrate. The erosion–corrosion results revealed that the smoothest wear track with the minimum erosion rate and wear depth was obtained for five- and seven-layered coatings. The failure mechanism of the bare substrate was influenced by plastic deformation via cutting and plowing, while the failure mechanism for coated samples was chipping and delamination. According to the wear results, the multilayer coatings showed a lower friction coefficient and better surface morphology that demonstrated their high ability for wear protection. 相似文献
87.
88.
We have fabricated high-quality <001> textured Pb(Zr0.54Ti0.46)O3 (PZT) thin films on (00l)Si with interposing <001> textured YBa2Cu3O7−δ (YBCO) and yttria-stabilized zirconia (YSZ) buffer layers using pulsed laser deposition (KrF excimer laser, λ, = 248 nm,
τ = 20 nanosecs). The YBCO layer provides a seed for PZT growth and can also act as an electrode for the PZT films, whereas
YSZ provides a diffusion barrier as well as a seed for the growth of YBCO films on (001)Si. These heterostructures were characterized
using x-ray diffraction, high-resolution transmission electron microscopy, and Rutherford backscattering techniques. The YSZ
films were deposited in oxygen ambient (∼9 × 10−4 Torr) at 775°C on (001)Si substrate having <001>YSZ // <001>Si texture. The YBCO thin films were deposited in-situ in oxygen
ambient (200 mTorr) at 650°C. The temperature and oxygen ambient for the PZT deposition were optimized to be 530°C and 0.4-0.6
Torr, respectively. The laser fluence to deposit this multilayer structure was 2.5-5.0 J/cm2. The <001> textured perovskite PZT films showed a dielectric constant of 800-1000, a saturation polarization of 37.81 μC/cm2, remnant polarization of 24.38 μC/cm2 and a coercive field of 125 kV/cm. The effects of processing parameters on microstructure and ferroelectric properties of
PZT films and device implications of these structures are discussed. 相似文献
89.
Melting behavior and superheating capacity of REBa2Cu3Oy films with nano‐layer buffered structures
下载免费PDF全文
![点击此处可从《Journal of the American Ceramic Society》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Wei Wang Hui Xiang Ghulam Hussain Dejing Yu Yisha Zhu Letian Zhang Sergey V. Samoilenkov Andrey R. Kaul Xin Yao 《Journal of the American Ceramic Society》2018,101(4):1704-1710
Using high temperature‐optical microscopy, in situ investigations were conducted on melting and superheating behaviors of REBa2Cu3O7?δ (RE123, RE = Nd, Gd) films, which were grown on nano‐layer buffered substrates. The results demonstrate that all buffered RE123 films have improved crystallinity and in‐plane alignments, leading to the higher superheating capability. In the first case, due to its good lattice match with the buffer material of Y123, the Nd123 film with the minimal extrinsic property grew from the superior interface. In the second circumstance, because of its stronger chemical bonding with the buffer layer of Gd2O3, the pure c‐axis oriented Gd123 film was fabricated. Moreover, the optimized thickness of buffer layer plays an important role in reducing interface energy of RE123 films and enhancing its superheating capacity. 相似文献
90.