全文获取类型
收费全文 | 147篇 |
免费 | 287篇 |
国内免费 | 217篇 |
专业分类
晶体学 | 5篇 |
物理学 | 266篇 |
无线电 | 380篇 |
出版年
2023年 | 1篇 |
2022年 | 12篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 9篇 |
2017年 | 8篇 |
2016年 | 14篇 |
2015年 | 6篇 |
2014年 | 30篇 |
2013年 | 16篇 |
2012年 | 40篇 |
2011年 | 33篇 |
2010年 | 31篇 |
2009年 | 51篇 |
2008年 | 30篇 |
2007年 | 50篇 |
2006年 | 42篇 |
2005年 | 59篇 |
2004年 | 40篇 |
2003年 | 25篇 |
2002年 | 29篇 |
2001年 | 49篇 |
2000年 | 9篇 |
1999年 | 11篇 |
1998年 | 6篇 |
1997年 | 1篇 |
1996年 | 8篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 3篇 |
排序方式: 共有651条查询结果,搜索用时 0 毫秒
81.
82.
83.
文章从集成电路(IC)发展规律出发,提出了可制造性设计的必要性和迫切性,并提出了基于可制造性设计的IC前道工序成本模型,为实现成本驱动设计的自动化和最优化打下必要的基础。 相似文献
84.
Unpassivated/passivated AlGaN/GaN high electron mobility transistors (HEMTs) were exposed to 1.25 MeV 60Co γ-rays at a dose of 1 Mrad(Si). The saturation drain current of the unpassivated devices decreased by 15% at 1 Mrad γ-dose, and the maximal transconductance decreased by 9.1% under the same condition; more- over, either forward or reverse gate bias current was significantly increased, while the threshold voltage is relatively unaffected. By sharp contrast, the passivated devices showed scarcely any change in saturation drain current and maximal transconductance at the same γ dose. Based on the differences between the passivated HEMTs and un- passivated HEMTs, adding the C–V measurement results, the obviously parameter degradation of the unpassivated AlGaN/GaN HEMTs is believed to be caused by the creation of electronegative surface state charges in sourcegate spacer and gate–drain spacer at the low dose (1 Mrad). These results reveal that the passivation is effective in reducing the effects of surface state charges induced by the 60Co γ-rays irradiation, so the passivation is an effective reinforced approach. 相似文献
85.
Nonpolar a-plane [110] GaN has been grown on r-plane [1■02] sapphire by MOCVD, and investigated by high resolution X-ray diffraction and atomic force microscopy. As opposed to the c-direction, this particular orientation is non-polar, and it avoids polarization charge, the associated screening charge and the consequent band bending. Both low-temperature GaN buffer and high-temperature AlN buffer are used for a-plane GaN growth on r-plane sapphire, and the triangular pits and pleat morphology come forth with different buffers, the possible reasons for which are discussed. The triangular and pleat direction are also investigated. A novel modulate buffer is used for a-plane GaN growth on r-plane sapphire, and with this technique, the crystal quality has been greatly improved. 相似文献
86.
Nonpolar (1120) a-plane GaN films have been grown by low-pressure metal-organic vapor deposition on r-plane (1102) sapphire substrate. The structural and electrical properties of the a-plane GaN films are investigated by high-resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM) and van der Pauw Hall measurement. It is found that the Hall voltage shows more anisotropy than that of the c-plane samples; furthermore, the mobility changes with the degree of the van der Pauw square diagonal to the c direction, which shows significant electrical anisotropy. Further research indicates that electron mobility is strongly influenced by edge dislocations. 相似文献
87.
88.
研制出在蓝宅石衬底上制作的MOS AIGaN/GaN HEMT.器件栅长1um,源漏间距4um,采用电子束蒸发4nm的Si02做栅介质.在4V栅压下器件饱和电流达到718mA/mm,最大跨导为172mS/mm,ft和fmax分别为8.1和15.3GHz.MOS HEMT栅反向泄漏电流与未做介质层的肖特基栅相比,在反偏10V时由2.1×10-8mA/mm减小到8.3×10-9mA/mm,栅漏电流减小2个数量级.MOS AIGaN/GaN HEMT采用薄的栅介质层,在保证减小栅泄漏电流的同时未引起器件跨导明显下降. 相似文献
89.
90.
VLSI容错设计研究进展(2)——功能成品率与可靠性的研究 总被引:1,自引:0,他引:1
带冗余的集成电路的成品率的估计对制造者来说是一个非常重要的问题。文中将集中分析和讨论带冗余的成品率模型和可靠性,给出了该领域研究进展的最新结果,并指出了进一步研究的方向和策略。 相似文献