全文获取类型
收费全文 | 359557篇 |
免费 | 28193篇 |
国内免费 | 15865篇 |
专业分类
电工技术 | 21117篇 |
技术理论 | 45篇 |
综合类 | 25521篇 |
化学工业 | 60012篇 |
金属工艺 | 20954篇 |
机械仪表 | 22594篇 |
建筑科学 | 27835篇 |
矿业工程 | 11737篇 |
能源动力 | 9781篇 |
轻工业 | 24182篇 |
水利工程 | 6794篇 |
石油天然气 | 23560篇 |
武器工业 | 2827篇 |
无线电 | 39029篇 |
一般工业技术 | 39612篇 |
冶金工业 | 18604篇 |
原子能技术 | 3680篇 |
自动化技术 | 45731篇 |
出版年
2024年 | 1491篇 |
2023年 | 5645篇 |
2022年 | 10014篇 |
2021年 | 14075篇 |
2020年 | 10587篇 |
2019年 | 8644篇 |
2018年 | 9948篇 |
2017年 | 11184篇 |
2016年 | 10198篇 |
2015年 | 13971篇 |
2014年 | 17584篇 |
2013年 | 21054篇 |
2012年 | 22852篇 |
2011年 | 25307篇 |
2010年 | 22365篇 |
2009年 | 21173篇 |
2008年 | 20731篇 |
2007年 | 19794篇 |
2006年 | 20149篇 |
2005年 | 17744篇 |
2004年 | 12017篇 |
2003年 | 10734篇 |
2002年 | 9952篇 |
2001年 | 8838篇 |
2000年 | 8807篇 |
1999年 | 9432篇 |
1998年 | 7218篇 |
1997年 | 6163篇 |
1996年 | 5840篇 |
1995年 | 4800篇 |
1994年 | 3903篇 |
1993年 | 2629篇 |
1992年 | 2077篇 |
1991年 | 1575篇 |
1990年 | 1236篇 |
1989年 | 996篇 |
1988年 | 832篇 |
1987年 | 524篇 |
1986年 | 410篇 |
1985年 | 259篇 |
1984年 | 206篇 |
1983年 | 164篇 |
1982年 | 128篇 |
1981年 | 76篇 |
1980年 | 97篇 |
1979年 | 44篇 |
1978年 | 17篇 |
1977年 | 23篇 |
1976年 | 28篇 |
1959年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
2-D dopant profiling in VLSI devices using dopant-selectiveetching: an atomic force microscopy study
We report a detailed mapping of a 2-D dopant profile on a fully processed industrial sample with large dynamic range and high spatial resolution by utilizing a dopant-selective etching process and Atomic Force Microscopy. The experimental results show excellent agreement with those obtained from SRP and SIMS as corroborative methods. We also discuss the most critical factors which influence the applicability, reproducibility, and reliability of this method 相似文献
55.
Chun Hu Ji Zhao Li G.P. Liu P. Worley E. White J. Kjar R. 《Electron Device Letters, IEEE》1995,16(2):61-63
The effects of the plasma etching process induced gate oxide damages on device's low frequency noise behavior are investigated on MOSFET's fabricated with different field plate perimeter to gate area ratio antennas. Abnormal 1/f noise spectrum with a shoulder centered in the frequency range of 100 and to 1 kHz was frequently observed in small geometry devices, and it is attributable to a nonuniform distribution of oxide traps induced by plasma etching process 相似文献
56.
57.
Air cleaning as a means of mitigating the risks arising from exposure to indoor radon progeny has been evaluated in a single-family house in the north eastem US. using an automated, semi-continuous activity-weighted size distribution measurement system. The measurements included radon concentration, condensation nuclei count, and activity-weighted size distribution of radon decay products. Measurements were made in the house with and without an operating air filtration system and with various particle sources common to normal indoor activities operating. Aerosols were generated by running water in a shower, candle burning, cigarette smoking, vacuuming, opening doors, and cooking. Using a room model, the changes in attachment rates, average attachment diameters, and deposition rates of the unattached fraction with and without the air cleaning system were calculated. In the presence of active aerosol sources, the air filtration unit typically reduced the concentration of particles within the hour following the end of particle generation. After candle burning, cigarette smoking, and vacuuming in the bedroom, the reductions of PAEC by air filtration are about 60% with the air filtration system operating in the bedroom. During cooking in the kitchen, the reductions of PAEC in the bedroom with the air filtration system were about 40%. However, for all cases the dose reductions were smaller than the particle and PAEC reductions. For those particles that were generated within the bedroom, there was a 20% to 50% reduction in dose. In the case of cooking where the door was open and particles infiltrated from the rest of the house, the dose reduction was only 5% on average and appears to be insignificant. Thus, the dose reductions were h e r than the reductions in activity concentration, but there were no cases where the estimated dose actually increased. 相似文献
58.
The authors reply to the comments by Koppelaar and Tolhuizen (see ibid. vol.46, no.9, p.573, 1998). They state that the optimum choice of the slopes used to perform the encoding process in a projection code always results in maximizing the minimum Hamming distance so that d=2 r 相似文献
59.
60.