全文获取类型
收费全文 | 1045篇 |
免费 | 33篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 24篇 |
综合类 | 8篇 |
化学工业 | 116篇 |
金属工艺 | 55篇 |
机械仪表 | 27篇 |
建筑科学 | 68篇 |
矿业工程 | 2篇 |
能源动力 | 32篇 |
轻工业 | 52篇 |
水利工程 | 2篇 |
石油天然气 | 8篇 |
无线电 | 114篇 |
一般工业技术 | 115篇 |
冶金工业 | 350篇 |
原子能技术 | 7篇 |
自动化技术 | 105篇 |
出版年
2022年 | 8篇 |
2021年 | 13篇 |
2020年 | 10篇 |
2019年 | 15篇 |
2018年 | 17篇 |
2017年 | 19篇 |
2016年 | 9篇 |
2015年 | 15篇 |
2014年 | 16篇 |
2013年 | 26篇 |
2012年 | 39篇 |
2011年 | 76篇 |
2010年 | 51篇 |
2009年 | 48篇 |
2008年 | 30篇 |
2007年 | 36篇 |
2006年 | 51篇 |
2005年 | 26篇 |
2004年 | 35篇 |
2003年 | 36篇 |
2002年 | 33篇 |
2001年 | 19篇 |
2000年 | 25篇 |
1999年 | 43篇 |
1998年 | 72篇 |
1997年 | 70篇 |
1996年 | 43篇 |
1995年 | 36篇 |
1994年 | 21篇 |
1993年 | 20篇 |
1992年 | 14篇 |
1991年 | 9篇 |
1990年 | 11篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 6篇 |
1976年 | 20篇 |
1975年 | 4篇 |
1973年 | 2篇 |
1971年 | 2篇 |
排序方式: 共有1085条查询结果,搜索用时 15 毫秒
1.
2.
Jinho Choi Sanghun Jung Deok Gun Park Jaegul Choo Niklas Elmqvist 《Computer Graphics Forum》2019,38(3):249-260
The majority of visualizations on the web are still stored as raster images, making them inaccessible to visually impaired users. We propose a deep‐neural‐network‐based approach that automatically recognizes key elements in a visualization, including a visualization type, graphical elements, labels, legends, and most importantly, the original data conveyed in the visualization. We leverage such extracted information to provide visually impaired people with the reading of the extracted information. Based on interviews with visually impaired users, we built a Google Chrome extension designed to work with screen reader software to automatically decode charts on a webpage using our pipeline. We compared the performance of the back‐end algorithm with existing methods and evaluated the utility using qualitative feedback from visually impaired users. 相似文献
3.
4.
K. Y. Cheah T. S. Tang Fujio Mizukami Shu-ichi Niwa Makoto Toba Y. M. Choo 《Journal of the American Oil Chemists' Society》1992,69(5):410-416
A new catalyst, ruthenium-tin-alumina is found to selectively hydrogenate oleic acid to 9-octadecen-1-ol (oleyl + elaidyl
alcohol) at low pressure with high yield. Catalyst preparation methods, catalyst raw materials and activation conditions have
a significant effect on the activity of the catalyst. The optimum atomic ratio of ruthenium to tin is about 1:2. Catalyst
prepared by an improved sol-gel method shows higher activity and selectivity than catalysts prepared by impregnation and coprecipitation
methods. Chloride is found to have a negative effect on catalytic activity. The best catalyst is prepared from chloride-free
ruthenium and tin raw materials. Under the optimum reaction conditions of 250°C and 5.6 MPa, the selectivities for 9-octadecen-1-ol
and total alcohol (9-octadecen-1-ol + stearyl alcohol) formation are 80.9% and 97%, respectively, at a conversion of 81.3%. 相似文献
5.
6.
中频变频器UFV故障探析 总被引:2,自引:1,他引:1
本文对中频变频器的UFV故障进行了系统试验和原因分析,并对UFV故障的关键因素进行了详细探析。 相似文献
7.
Latent or sub-clinical hepatic encephalopathy is a recognized complication of cirrhosis and is thought to represent one end of the spectrum of neuropsychiatric impairment, which occurrs as a result of portal-systemic shunting. We studied the psychometric, analyzed electroencephalography (EEG), and venous blood ammonia responses to an oral glutamine challenge in 17 patients with cirrhosis and in 4 normal controls. The cirrhotics were attending for liver transplant assessment and had no clinical evidence of hepatic encephalopathy. The oral glutamine challenge was repeated following liver transplantation. Five of sixteen patients (31%) showed impaired performance on at least one of the baseline psychometric tests. There was a correlation between fasting venous ammonia and choice reaction time (r = .7, P < .01). Following glutamine challenge there was a significant increase in blood ammonia from a mean fasting value ranging between 58 micromol/L to 120 micromol/L (P < .01), between significant prolongation of reaction times of 387 ms to 428 ms (P < .01), and an increase in mean EEG amplitude between 68.5 microV to 78.6 microV (P < .001). Four normal controls who were challenged with glutamine and 6 cirrhotic patients who were challenged with water showed no change in any of these parameters. Following orthotopic liver transplantation (OLT) the eight patients studied had normal baseline psychomotor performance with significant improvements in digit symbol, digit span, information processing, number connection tests (P < .05), and reaction time (P < .005). Posttransplantation, there were no significant changes in blood ammonia, analyzed EEG, or choice reaction time in response to oral glutamine challenge (six patients). We conclude that short lived changes in blood ammonia (in cirrhotics) can cause significant impairment of sensitive tests of brain function and that psychometric performance is improved following OLT. 相似文献
8.
Don Alfano May Ann Choo 《电子设计应用》2006,(7):141-143
激光二极管是宽带调幅光纤发射系统的核心器件。光纤系统依赖于激光的稳定性,但未受调节控制的激光二极管特性却常因制造误差、温度和使用日久所造成的参数改变而变得不稳定。因此,光纤通信系统需要专用电路来控制重要的激光二极管参数,以确保它们稳定操作。虽然激光控制电路都 相似文献
9.
10.