全文获取类型
收费全文 | 6004篇 |
免费 | 68篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 60篇 |
综合类 | 2篇 |
化学工业 | 611篇 |
金属工艺 | 58篇 |
机械仪表 | 59篇 |
建筑科学 | 78篇 |
矿业工程 | 29篇 |
能源动力 | 44篇 |
轻工业 | 313篇 |
水利工程 | 20篇 |
石油天然气 | 8篇 |
无线电 | 534篇 |
一般工业技术 | 462篇 |
冶金工业 | 3370篇 |
原子能技术 | 35篇 |
自动化技术 | 390篇 |
出版年
2021年 | 28篇 |
2020年 | 21篇 |
2018年 | 39篇 |
2017年 | 29篇 |
2016年 | 20篇 |
2015年 | 25篇 |
2014年 | 49篇 |
2013年 | 211篇 |
2012年 | 77篇 |
2011年 | 126篇 |
2010年 | 98篇 |
2009年 | 101篇 |
2008年 | 109篇 |
2007年 | 126篇 |
2006年 | 113篇 |
2005年 | 93篇 |
2004年 | 82篇 |
2003年 | 101篇 |
2002年 | 68篇 |
2001年 | 78篇 |
2000年 | 66篇 |
1999年 | 158篇 |
1998年 | 954篇 |
1997年 | 564篇 |
1996年 | 376篇 |
1995年 | 247篇 |
1994年 | 209篇 |
1993年 | 248篇 |
1992年 | 91篇 |
1991年 | 85篇 |
1990年 | 80篇 |
1989年 | 75篇 |
1988年 | 88篇 |
1987年 | 65篇 |
1986年 | 63篇 |
1985年 | 70篇 |
1984年 | 33篇 |
1983年 | 45篇 |
1982年 | 58篇 |
1981年 | 59篇 |
1980年 | 66篇 |
1979年 | 34篇 |
1978年 | 35篇 |
1977年 | 124篇 |
1976年 | 244篇 |
1975年 | 46篇 |
1974年 | 18篇 |
1973年 | 23篇 |
1972年 | 29篇 |
1966年 | 19篇 |
排序方式: 共有6073条查询结果,搜索用时 0 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.
3.
A Gopal G Li Mandri DL King C Marboe S Homma 《Canadian Metallurgical Quarterly》1994,105(6):1885-1887
Cardiac papillary fibroelastomas are unusual, frond-like growths typically found on cardiac valves, diagnosed incidentally on autopsy or cardiac surgery, but rarely during life. We report a rare case of an aortic valve papillary fibroelastoma detected by transthoracic echocardiography and confirmed by histologic study. 相似文献
4.
5.
D. M. Van Wie D. G. Drewry Jr. D. E. King C. M. Hudson 《Journal of Materials Science》2004,39(19):5915-5924
Hypersonic flight powered by airbreathing engines offers the potential for faster response time at long ranges, and reduced cost for access-to-space. In the present paper the operating environment of typical hypersonic vehicles are discussed, including results for the radiation equilibrium wall temperature of external vehicle surfaces and the flow properties through three sample engines spanning the range of hydrocarbon-fueled Mach 4-8 flight and hydrogen-fueled flight at speeds up to Mach 17. Flow conditions at several locations through the sample engines were calculated to provide indications of the required operating flow environment. Additional system consideration such a seals, joints, vehicle integration and in-service engineering are addressed. 相似文献
6.
Digant Gupta Christopher G Lis Sadie L Dahlk Jessica King Pankaj G Vashi James F Grutsch Carolyn A Lammersfeld 《Nutrition journal》2008,7(1):19
Background
Bioelectrical Impedance (BIA) derived phase angle is increasingly being used as an objective indicator of nutritional status in advanced cancer. Subjective Global Assessment (SGA) is a subjective method of nutritional status. The objective of this study was to investigate the association between BIA derived phase angle and SGA in advanced colorectal cancer. 相似文献7.
Xin Sun Qiang Lu Moroz V. Takeuchi H. Gebara G. Wetzel J. Shuji Ikeda Changhwan Shin Tsu-Jae King Liu 《Electron Device Letters, IEEE》2008,29(5):491-493
A tri-gate bulk MOSFET design utilizing a low-aspect-ratio channel is proposed to provide an evolutionary pathway for CMOS scaling to the end of the roadmap. 3-D device simulations indicate that this design offers the advantages of a multi-gate FET (reduced variability in performance and improved scalability) together with the advantages of a conventional planar MOSFET (low substrate cost and capability for dynamic threshold-voltage control). 相似文献
8.
BACKGROUND: There is controversy over whether colonization with drug-resistant organisms is a contraindication to lung transplantation. METHODS: We undertook a retrospective review of the results of lung transplantation for patients with cystic fibrosis (CF) at Duke University Medical Center. RESULTS: As of May 1996, 21 patients with CF underwent bilateral lung transplantation. The first patient died within 24 h of transplantation from sepsis due to Stenotrophomonas maltophilia. Of the remaining 20 patients, 17 (85%) are alive and in stable condition. The three deaths were related primarily to bronchiolitis obliterans at 4 and 18 months in two patients and to cytomegalovirus pneumonitis at 5 months in the other patient. The 17 surviving patients have been followed up for a mean of 13 months (range, 0.5 to 34 months). Most of them were colonized and infected with multidrug-resistant organisms before transplantation. Following transplantation, 11 patients had complications from infections. One patient had bacteremia due to a panresistant Burkholderia cepacia and was treated successfully. Two patients had bacteremia and wound infection due to Burkholderia gladioli, previously thought to be pathogenic only in plants. Both patients were treated successfully. Of the six patients with Aspergillus fumigatus isolated from cultures before transplantation, only one had invasive disease following transplantation and responded to treatment. CONCLUSION: The organisms present before transplantation were not the primary cause of mortality in our patient population. Our findings suggest that lung transplantation should be considered in CF patients infected with multidrug-resistant organisms. 相似文献
9.
We demonstrate multi-emitter Si/GexSi1-x n-p-n heterojunction bipolar transistors (HBT's) which require no base contact for transistor operation. The base current is supplied by the additional emitter contact under reverse bias due to the heavy doping of the emitter-base junction. Large-area HBT test structures exhibit good transistor characteristics, with current gain β≈400 regardless of whether the base current is supplied by a test base electrode or one of the emitter contacts. These devices have enhanced logic functionality because of emitter contact symmetry. Since device fabrication does not require base electrode formation, the number of processing steps can be reduced without significant penalty to HBT performance 相似文献
10.
Wideband chirp measurement technique for high bit rate sources 总被引:1,自引:0,他引:1
A Mach Zehnder (MZ) interferometer has been used as an optical discriminator to measure the time-resolved frequency chirp of an optical source 相似文献