全文获取类型
收费全文 | 822篇 |
免费 | 55篇 |
国内免费 | 42篇 |
专业分类
电工技术 | 72篇 |
综合类 | 30篇 |
化学工业 | 30篇 |
金属工艺 | 115篇 |
机械仪表 | 101篇 |
建筑科学 | 17篇 |
矿业工程 | 12篇 |
能源动力 | 25篇 |
轻工业 | 6篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
武器工业 | 3篇 |
无线电 | 241篇 |
一般工业技术 | 134篇 |
冶金工业 | 110篇 |
原子能技术 | 3篇 |
自动化技术 | 17篇 |
出版年
2023年 | 10篇 |
2022年 | 6篇 |
2021年 | 19篇 |
2020年 | 24篇 |
2019年 | 22篇 |
2018年 | 19篇 |
2017年 | 26篇 |
2016年 | 25篇 |
2015年 | 22篇 |
2014年 | 44篇 |
2013年 | 32篇 |
2012年 | 39篇 |
2011年 | 54篇 |
2010年 | 32篇 |
2009年 | 52篇 |
2008年 | 35篇 |
2007年 | 51篇 |
2006年 | 43篇 |
2005年 | 29篇 |
2004年 | 48篇 |
2003年 | 28篇 |
2002年 | 39篇 |
2001年 | 37篇 |
2000年 | 17篇 |
1999年 | 21篇 |
1998年 | 28篇 |
1997年 | 19篇 |
1996年 | 23篇 |
1995年 | 14篇 |
1994年 | 9篇 |
1993年 | 2篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 11篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1977年 | 2篇 |
1974年 | 2篇 |
排序方式: 共有919条查询结果,搜索用时 15 毫秒
91.
92.
T. N. Oder T. L. Sung M. Barlow J. R. Williams A. C. Ahyi T. Isaacs-Smith 《Journal of Electronic Materials》2009,38(6):772-777
High-temperature processing was used to improve the barrier properties of three sets of n-type 4H-SiC Schottky diodes fabricated with Ni Schottky contacts. We obtained an optimum average barrier height of 1.78 eV
and an ideality factor of 1.09 using current–voltage measurements on diodes annealed in vacuum at 500°C for 24 h. Nonannealed
contacts had an average barrier height of 1.48 eV and an ideality factor of 1.85. The Rutherford backscattering spectra of
the Ni/SiC contacts revealed the formation of a nickel silicide at the interface, accompanied by a substantial reduction in
oxygen following annealing. 相似文献
93.
A Novel Stress Characterization Technique for the Development of Low-Stress Ohmic Contacts to HgCdTe
D. D’Orsogna P. Lamarre E. Bellotti P. E. Barbone F. Smith C. Fulk P. LoVecchio M. B. Reine S. P. Tobin J. Markunas 《Journal of Electronic Materials》2009,38(8):1698-1706
HgCdTe material intended for long-wavelength infrared detection is particularly susceptible to damage from stress. As a result,
an ideal ohmic contact needs to have good adhesion and low specific contact resistance. The contact should act as a diffusion
barrier and induce the least amount of stress in the underlying material. In this paper we present a set of stress measurements
from different ohmic contact materials deposited on short- and long-wavelength HgCdTe films grown by liquid-phase epitaxy
(LPE). Using a new experimental technique we remove the substrate and measure the stress induced on single- and multilayered
HgCdTe cantilevers. To interpret our results, we develop a theoretical model that describes the physics of elastic deformation
in HgCdTe layers. Our model is based on classical thin-plate bending theory and explicitly takes into account the realistic
boundary conditions that are present in the experimental setup by using a variational approach. 相似文献
94.
This paper reports the DC steady-state current-voltage and conductance-voltage characteristics of a Bipolar Field-Effect Transistor(BiFET) under the unipolar(electron) current mode of operation,with bipolar(elec-tron and hole) charge distributions considered.The model BiFET example presented has two MOS-gates on the two surfaces of a thin pure silicon base layer with electron and hole contacts on both edges of the thin base.The hole contacts on both edges of the thin pure base layer are grounded to give zer... 相似文献
95.
This paper reports the physical realization of the Bipolar Field-Effect Transistor (BiFET) and its one-transistor basic building block circuits. Examples are given for the one and two MOS gates on thin and thick, pure and impure base, with electron and hole contacts, and the corresponding theoretical current-voltage characteristics previously computed by us, without generation-recombination-trapping-tunneling of electrons and holes. These ex-amples include the one-MOS-gate on semi-infinite thick impure base transistor (the bulk transistor) and the impure-thin-base Silicon-on-Insulator (SOI) transistor and the two-MOS-gates on thin base transistors (the FinFET and the Thin Film Transistor TFT). Figures are given with the cross-section views containing the electron and hole concen-tration and current density distributions and trajectories and the corresponding DC current-voltage characteristics. 相似文献
96.
对不同状态含氮奥氏体钢板和马氏体钢板进行了抗枪弹与抗杆式模拟弹试验,分析了它们的穿甲机理。含氮奥氏体钢具有优良的抗弹性能,并优于传统马氏体钢的抗弹性能。马氏体钢抗杆式模拟弹防护系数随着强度的提高而提高,呈线性关系,含氮奥氏体钢穿甲防护系数远远高于同一强度级别的马氏体钢。研究表明,含氮奥氏体钢的抗弹性能的提高主要通过冲击硬化,动态强度明显提高,以及通过塑性变形区域增加,使弹丸更多的能量转换成塑性变形能。 相似文献
97.
98.
介绍了石油钻机专用新型CZ28-1250Q/10直流电磁接触器的总体结构和特点,重点研究讨论了新型CZ28-1250Q/10直流电磁接触器电磁系统的设计和关键技术参数的计算. 相似文献
99.
Peter A. Hersh Calvin J. Curtis Maikel F.A.M. van Hest John J. Kreuder Robert Pasquarelli Alex Miedaner David S. Ginley 《Progress in Photovoltaics: Research and Applications》2011,19(8):973-976
This study reports the inkjet printing of Ag front contacts on Aluminum doped Zinc Oxide (AZO)/intrinsic Zinc Oxide (i‐ZnO)/CdS/Cu(In1−xGax)Se2 (CIGS)/Mo thin film photovoltaic cells. The printed Ag contacts are being developed to replace the currently employed evaporated Ni/Al bi‐layer contacts. Inkjet deposition conditions were optimized to reduce line resistivity and reduce contact resistance to the Al:ZnO layer. Ag lines printed at a substrate temperature of 200°C showed a line resistivity of 2.06 µΩ · cm and a contact resistance to Al:ZnO of 8.2 ± 0.2 mΩ · cm2 compared to 6.93 ± 0.3 mΩ · cm2 for thermally evaporated contacts. These deposition conditions were used to deposit front contacts onto high quality CIGS thin film photovoltaic cells. The heating required to print the Ag contacts caused the performance to degrade compared to similar devices with evaporated Ni/Al contacts that were not heated. Devices with inkjet printed contacts showed 11.4% conversion efficiency compared to 14.8% with evaporated contacts. Strategies to minimize heating, which is detrimental for efficiency, during inkjet printing are proposed. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
100.
Thin film transistors (TFT) with an indium based mixed oxide semiconductor are investigated for titanium–gold top-contacts. It is noticed that upon post annealing, in order to remove chemical residuals from top-contact lift-off steps, oxidation of titanium occurs depending on the annealing conditions. Mobility of the TFT is strongly affected by contact oxidation arising from this post lift-off annealing process. Oxidation of the top-contact is facilitated by adsorbed surface oxygen or out-diffusing oxygen from the semiconductor depending on the post lift-off annealing conditions. A passivation layer that binds effectively to surface vacancies and removes adsorbed oxygen species from the semiconductor surface is demonstrated. The combinations of this passivation layer with relatively low temperature and short post lift-off annealing in an oxygen deficient environment result in significantly reduced contact oxidation and subsequently better transistor performance. Contact resistance as low as 90 Ω cm and mobility as high as 5.3 cm2/V s are obtained for solution processed mixed metal oxide semiconductor in top-contact geometry. 相似文献