全文获取类型
收费全文 | 1461篇 |
免费 | 43篇 |
国内免费 | 7篇 |
学科分类
工业技术 | 1511篇 |
出版年
2023年 | 4篇 |
2022年 | 3篇 |
2021年 | 18篇 |
2020年 | 7篇 |
2019年 | 14篇 |
2018年 | 21篇 |
2017年 | 24篇 |
2016年 | 30篇 |
2015年 | 23篇 |
2014年 | 33篇 |
2013年 | 129篇 |
2012年 | 55篇 |
2011年 | 63篇 |
2010年 | 74篇 |
2009年 | 83篇 |
2008年 | 81篇 |
2007年 | 62篇 |
2006年 | 49篇 |
2005年 | 41篇 |
2004年 | 49篇 |
2003年 | 61篇 |
2002年 | 41篇 |
2001年 | 45篇 |
2000年 | 31篇 |
1999年 | 48篇 |
1998年 | 67篇 |
1997年 | 49篇 |
1996年 | 47篇 |
1995年 | 31篇 |
1994年 | 26篇 |
1993年 | 44篇 |
1992年 | 19篇 |
1991年 | 26篇 |
1990年 | 28篇 |
1989年 | 15篇 |
1988年 | 14篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 5篇 |
1976年 | 2篇 |
1974年 | 1篇 |
1971年 | 1篇 |
1970年 | 2篇 |
排序方式: 共有1511条查询结果,搜索用时 31 毫秒
11.
Chuxiang Li Jianhua Lu Jun Gu Ming L. Liou 《The Journal of VLSI Signal Processing》2003,33(3):277-285
In this paper, error-resilient schemes are proposed to support robust video transmission for digital terrestrial TV broadcasting (DTTB). In particular, a temporal error concealment incorporated with a low-complexity block-matching is developed, achieving an effective reception of predictive pictures in harsh terrestrial environment. Special algorithms are also designed for isolated I-pictures. Moreover, combined with an intra/inter case prediction, an adaptive error concealment scheme is further contrived to fit for different error conditions. Extensive simulations have been conducted under various DTTB channel conditions, even with a very high packet error rate, to verify the effectiveness of the proposed schemes. 相似文献
12.
Shubneesh Batra Nanseng Jeng Akif Sultan Kyle Picone Surya Bhattacharya Keun-Hyung Park Sanjay Banerjee David Kao Monte Manning Chuck Dennison 《Journal of Electronic Materials》1993,22(5):551-554
When dopants are indiffused from a heavily implanted polycrystalline silicon film deposited on a silicon substrate, high thermal
budget annealing can cause the interfacial “native” oxide at the polycrystalline silicon-single crystal silicon interface
to break up into oxide clusters, causing epitaxial realignment of the polycrystalline silicon layer with respect to the silicon
substrate. Anomalous transient enhanced diffusion occurs during epitaxial realignment and this has adverse effects on the
leakage characteristics of the shallow junctions formed in the silicon substrate using this technique. The degradation in
the leakage current is mainly due to increased generation-recombination in the depletion region because of defect injection
from the interface. 相似文献
13.
The present study was undertaken to evaluate the postoperative relapse from the period of unwiring to 1 year postoperatively and its correlation to the amount of mandibular setback and change in vertical dimension after mandibular bilateral sagittal split osteotomy. Twenty-seven patients were evaluated cephalometrically by the time preoperatively, 6 weeks, 6 months and 1 year postoperatively. It was found that 1) the average amount of mandibular setback at pogonion point, 6 weeks postoperatively, is 7.6mm backward and 1.9mm downward, 2) the average amount of horizontal relapse at pogonion point, 6 months and 1 year postoperatively, are 1.9mm and 2.3mm respectively. 86% of the horizontal relapse, 1 year postoperatively, occurs in the first 6 months after removal of intermaxillary fixation, 3) the average amount of vertical relapse at pogonion point, 6 months and 1 year postoperatively, are 0.9mm and 1.1mm upward. 82% of the vertical relapse, 1 year postoperatively, occurs in the first 6 months after removal of intermaxillary fixation, 4) the amount of 1 year postoperatively horizontal relapse is significantly correlated both with the amount of horizontal mandibular set back and vertical downward change (r = 0.58, 0.67, p < 0.001), whereas the amount of vertical relapse is with the vertical downward change only, but horizontal setback isn't. 相似文献
14.
15.
The viability of developing an SiC fibre-reinforced titanium/titanium aluminide hybrid matrix composite was explored. The
hybrid composites are expected to be used at temperatures beyond those attainable in conventional titanium matrix composites
while improving the damage tolerance of the titanium aluminide matrix composites. The room-temperature mechanical characteristics
studied were tensile strength, fracture toughness, low-cycle fatigue life and fatigue crack growth rate. The mechanisms of
damage initiation and propagation under various loading conditions were also characterized. The directions for developing
a satisfactory composite with hybrid titanium/titanium aluminide matrix are also addressed. 相似文献
16.
17.
Sheng-Lueng Chung MuDer Jeng 《Robotics & Automation Magazine, IEEE》2004,11(3):14-21
In this paper, the scenario normalization technique is addressed, which is very useful in the context of generic equipment control, where an equipment-control system (ECS) is to control several pieces of equipment, possibly of different types. This paper begins with a background introduction to a photolithographic cell and the concept of generic equipment control adopted in semiconductor fabs. The concept of message modulation that translates in semantics context the sequence flows between the high-level ECS and the low-level equipment is presented. The main idea relies on the operational scenarios modeling by the sequence diagram; message translation based on semantics analysis; the derivation of production rules and the implementation of them on an event-triggering platform. Scenarios, thus obtained and presented to the high-level ECS by the coordinator, are then in compliance with the normalized scenario as required by the generic equipment controller. The significance of the proposed normalization techniques has the following implication: when different equipment are included in a cell operation, it is not necessary to rewrite control programs but to add relatively simpler transformation sequences enabling the use of the standard ECS function. From the control point of view, the controlled systems of stepper and track can be modeled as discrete event dynamic ones if operation coordination is considered. 相似文献
18.
19.
Shui-Jinn Wang Shiue-Lung Chen Kai-Ming Uang Wei-Chi Lee Tron-Min Chen Chao-Hsuing Chen Bor-wen Liou 《Photonics Technology Letters, IEEE》2006,18(10):1146-1148
In this study, the performance of vertical-structured high-power GaN-based light-emitting diodes (VM-LEDs) with a transparent and low-resistant indium-zinc oxide (IZO) film as a current spreading layer (CSL) was investigated. Nickel electroplating and patterned laser liftoff techniques were employed for the transfer of sapphire substrate to nickel substrate. The novel IZO CSL atop n-side-up VM-LEDs offering benefits of superior current spreading ability, larger extraction efficiency, and lower forward voltage drop was demonstrated. As compared to the regular LED without IZO CSL, the use of an IZO CSL with an optimum thickness of around 300 nm leads to an increase in light output power by 97.1 (67.8)% and a decrease in forward voltage drop by 4.9 (15.5)% under an injection current of 350 (800) mA. 相似文献
20.
Tsun-Lai Hsu Jeng Gong Keh-Yuh Yu 《Electron Devices, IEEE Transactions on》1995,42(10):1868-1871
A simple model for the analysis of the ac stress effect in poly-emitter bipolar transistors is presented. Apart from the reverse-bias induced hot-carrier effects, the forward-bias recovery effect is a key factor under ac stress, it obviously suppresses the base current degradation of the device which is caused during the reverse-bias periods. In this work, we derived the relationship between the excess base current and the stress time for different ac stress conditions. This model is verified with experimental results.<> 相似文献