全文获取类型
收费全文 | 3857篇 |
免费 | 50篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 151篇 |
化学工业 | 532篇 |
金属工艺 | 1590篇 |
机械仪表 | 51篇 |
建筑科学 | 41篇 |
矿业工程 | 1篇 |
能源动力 | 67篇 |
轻工业 | 127篇 |
水利工程 | 6篇 |
石油天然气 | 1篇 |
无线电 | 282篇 |
一般工业技术 | 399篇 |
冶金工业 | 442篇 |
原子能技术 | 56篇 |
自动化技术 | 168篇 |
出版年
2023年 | 12篇 |
2022年 | 30篇 |
2021年 | 36篇 |
2020年 | 22篇 |
2019年 | 24篇 |
2018年 | 24篇 |
2017年 | 23篇 |
2016年 | 47篇 |
2015年 | 24篇 |
2014年 | 49篇 |
2013年 | 149篇 |
2012年 | 121篇 |
2011年 | 141篇 |
2010年 | 92篇 |
2009年 | 125篇 |
2008年 | 152篇 |
2007年 | 127篇 |
2006年 | 115篇 |
2005年 | 100篇 |
2004年 | 82篇 |
2003年 | 130篇 |
2002年 | 141篇 |
2001年 | 129篇 |
2000年 | 109篇 |
1999年 | 130篇 |
1998年 | 250篇 |
1997年 | 226篇 |
1996年 | 165篇 |
1995年 | 108篇 |
1994年 | 115篇 |
1993年 | 167篇 |
1992年 | 160篇 |
1991年 | 147篇 |
1990年 | 55篇 |
1989年 | 44篇 |
1988年 | 32篇 |
1987年 | 35篇 |
1986年 | 40篇 |
1985年 | 34篇 |
1984年 | 45篇 |
1983年 | 27篇 |
1982年 | 18篇 |
1981年 | 20篇 |
1980年 | 18篇 |
1979年 | 18篇 |
1978年 | 13篇 |
1976年 | 15篇 |
1974年 | 5篇 |
1973年 | 10篇 |
1971年 | 3篇 |
排序方式: 共有3914条查询结果,搜索用时 15 毫秒
1.
Annals of Mathematics and Artificial Intelligence - The inner representation of deep neural networks (DNNs) is indecipherable, which makes it difficult to tune DNN models, control their training... 相似文献
2.
Electrical Breakdown Properties and Space Charge Formation in High Temperature Region in Ultraviolet Ray Irradiated PVC
下载免费PDF全文
![点击此处可从《Electrical Engineering in Japan》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Polyvinyl chloride (PVC) is the most popular insulating material for electric wiring instruments. However, an exothermic reaction above 150 °C may cause deterioration of the insulating properties of PVC. Therefore, it is important to clarify the heat degradation in PVC, not only to investigate the ignition of electrical wiring products but also to use electrical products safely. It is known that ultraviolet (UV) irradiation causes chemical deterioration of PVC and an increase in its conductivity. Generally, it has been thought that the electrical breakdown properties, electrical conduction, and insulating performance are affected by space charge accumulation in an insulating material. A high temperature pulsed electroacoustic (PEA) system usable up to 250 °C has been developed, and the PEA system can measure the space charge distribution and conduction current in the high temperature range simultaneously. In this investigation, the space charge distribution and conduction current were measured up to electrical breakdown in a non‐UV irradiated sample (normal PVC) and in 353 nm and 253 nm UV‐irradiated PVC samples in the range from room temperature to 200 °C in a DC electric field. In the short wavelength UV irradiated PVC sample (253 nm, 300 h), a deterioration of breakdown strength at 90 °C to 150 °C and negative packet‐like charges were observed at 60 °C and 100 °C, a positive charge accumulated in front of both the anode and cathode above 90 °C, and a higher electric field near the cathode side because the positive charge of the cathode side was greater. 相似文献
3.
4.
5.
6.
7.
H. Okamoto 《Journal of Phase Equilibria and Diffusion》2002,23(4):384-385
8.
9.
1-GHz-spaced 16-channel arrayed-waveguide grating for a wavelength reference standard in DWDM network systems 总被引:3,自引:0,他引:3
We fabricated a 1-GHz-spaced 16-channel arrayed-waveguide grating (AWG) by using a new AWG configuration where the path of each arrayed waveguide winds backward and forward across a 4-in diameter wafer without crossing any other waveguides. The ultra-narrow (< 1 GHz) and stable transmission bands of this AWG can be used to construct a wavelength reference standard covering the S, C, and L bands in the dense wavelength-division-multiplexing network systems whose frequency deviation is /spl plusmn/160 MHz. 相似文献
10.
Wakejima A. Matsunaga K. Okamoto Y. Ando Y. Nakayama T. Miyamoto H. 《Electronics letters》2005,41(25):1371-1372
A single-ended amplifier using small packaged GaN-FETs exhibits a record 2.14 GHz W-CDMA output power. The amplifier, composed of paralleled 48 mm gate periphery FET die, delivers a peak saturated output power of 371 W with a linear gain of 11.2 dB at a drain voltage of 45 V under 2.14 GHz 3GPP W-CDMA signal input. The output power density (output power/package size) of 1.1 W/mm/sup 2/ is twice as high as that of the existing over 300 W GaAs-FET amplifiers. A low 5 MHz offset ACLR of -36 dBc with a drain efficiency of 24% is also obtained at 8 dB power back off from the saturated output power. 相似文献