全文获取类型
收费全文 | 95510篇 |
免费 | 1629篇 |
国内免费 | 450篇 |
专业分类
电工技术 | 951篇 |
综合类 | 2333篇 |
化学工业 | 13830篇 |
金属工艺 | 5171篇 |
机械仪表 | 3817篇 |
建筑科学 | 2366篇 |
矿业工程 | 565篇 |
能源动力 | 1531篇 |
轻工业 | 4600篇 |
水利工程 | 1355篇 |
石油天然气 | 355篇 |
无线电 | 11495篇 |
一般工业技术 | 18908篇 |
冶金工业 | 3307篇 |
原子能技术 | 423篇 |
自动化技术 | 26582篇 |
出版年
2023年 | 165篇 |
2022年 | 233篇 |
2021年 | 441篇 |
2020年 | 285篇 |
2019年 | 331篇 |
2018年 | 14729篇 |
2017年 | 13663篇 |
2016年 | 10315篇 |
2015年 | 973篇 |
2014年 | 772篇 |
2013年 | 1001篇 |
2012年 | 3917篇 |
2011年 | 10282篇 |
2010年 | 8908篇 |
2009年 | 6260篇 |
2008年 | 7409篇 |
2007年 | 8261篇 |
2006年 | 602篇 |
2005年 | 1643篇 |
2004年 | 1524篇 |
2003年 | 1523篇 |
2002年 | 912篇 |
2001年 | 386篇 |
2000年 | 435篇 |
1999年 | 303篇 |
1998年 | 412篇 |
1997年 | 265篇 |
1996年 | 222篇 |
1995年 | 132篇 |
1994年 | 123篇 |
1993年 | 99篇 |
1992年 | 76篇 |
1991年 | 78篇 |
1990年 | 50篇 |
1989年 | 57篇 |
1988年 | 39篇 |
1987年 | 39篇 |
1985年 | 30篇 |
1968年 | 43篇 |
1967年 | 33篇 |
1966年 | 43篇 |
1965年 | 44篇 |
1963年 | 28篇 |
1960年 | 30篇 |
1959年 | 35篇 |
1958年 | 37篇 |
1957年 | 36篇 |
1956年 | 34篇 |
1955年 | 63篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Jeong-Soo Lee Yang-Kyu Choi Daewon Ha Balasubramanian S. Tsu-Jae King Bokor J. 《Electron Device Letters, IEEE》2003,24(3):186-188
The hydrogen annealing process has been used to improve surface roughness of the Si-fin in CMOS FinFETs for the first time. Hydrogen annealing was performed after Si-fin etch and before gate oxidation. As a result, increased saturation current with a lowered threshold voltage and a decreased low-frequency noise level over the entire range of drain current have been attained. The low-frequency noise characteristics indicate that the oxide trap density is reduced by a factor of 3 due to annealing. These results suggest that hydrogen annealing is very effective for improving device performance and for attaining a high-quality surface of the etched Si-fin. 相似文献
2.
Chel-Jong Choi Tae-Yeon Seong Key-Min Lee Joo-Hyoung Lee Young-Jin Park Hi-Deok Lee 《Electron Device Letters, IEEE》2002,23(4):188-190
The leakage mechanism in p+/n shallow junctions fabricated using Co silicidation and shallow trench isolation processes has been investigated using transmission electron microscopy (TEM) combined with selective chemical etching. TEM and TSUPREM-4 simulation results show that dopant profiles bend upward near the edge of the active region. The formation of the abnormal profile is attributed to transient enhanced diffusion induced by source/drain implantation. Based on the TEM and simulation results, it is suggested that the shallower junctions formed near the active edge can serve as a source for leakage current in the silicided p+ /n shallow junctions 相似文献
3.
The purpose of this paper is to evaluate two methods of assessing the productivity and quality impact of Computer Aided Software Engineering (CASE) and Fourth Generation Language (4GL) technologies: (1) by the retrospective method; and (2) the cross-sectional method. Both methods involve the use of questionnaire surveys. Developers' perceptions depend on the context in which they are expressed and this includes expectations about the effectiveness of a given software product. Consequently, it is generally not reliable to base inferences about the relative merits of CASE and 4GLs on a cross-sectional comparison of two separate samples of users. The retrospective method that requires each respondent to directly compare different products is shown to be more reliable. However, there may be scope to employ cross-sectional comparisons of the findings from different samples where both sets of respondents use the same reference point for their judgements, and where numerical rather than verbal rating scales are used to measure perceptions. 相似文献
4.
5.
6.
J-M Choe 《欧洲信息系统杂志》2002,11(2):142-158
This study empirically examined the organisational learning effects of the nonfinancial performance information provided by management accounting information systems (MAISs) under advanced manufacturing technology (AMT). In this study, a target costing system and the frequent and quick reporting of information were considered the facilitators of learning. First, we examined the relationships between AMT level and the amount of nonfinancial performance information produced by MAISs. The empirical results showed that there are significant positive relationships between the level of AMT and nonfinancial performance information. With a systems approach, we also proved the impact of the relationships among AMT levels, nonfinancial performance information and learning facilitators on the organisational performance of a firm. The results of our research suggest that under a high level of AMT, for the provision of information to result in an increase of performance through organisational learning, a target costing system must be introduced and a large amount of information should be provided frequently and quickly. The results of this study also showed that although AMT level may be low, fairly well-arranged facilitators and a moderately large amount of information may be necessary for the improvement of performance. In conclusion, effective organisational learning depends on the provision of relevant information as well as efficient learning support mechanisms. 相似文献
7.
8.
Jong-Hwan Kim Yeon-Chan Hong Sung-Jun Lee Keh-Kun Choi 《Industrial Electronics, IEEE Transactions on》1989,36(3):361-364
A direct adaptive control scheme is proposed for nonminimum-phase systems in which controller parameters are estimated from the recursive least-squares algorithm and additional auxiliary parameters are obtained from the proposed polynomial identity. A local convergence is guaranteed without any extra condition. Integral action is incorporated into the adaptive controller to eliminate the steady-state error and to satisfy a condition of the unique solution for the polynomial identity. The control law used in this scheme is based on the set-point-on-I-only proportional-integral-derivative (PID) structure 相似文献
9.
10.