全文获取类型
收费全文 | 426675篇 |
免费 | 7068篇 |
国内免费 | 2221篇 |
专业分类
电工技术 | 8710篇 |
技术理论 | 5篇 |
综合类 | 1643篇 |
化学工业 | 64042篇 |
金属工艺 | 17980篇 |
机械仪表 | 14917篇 |
建筑科学 | 10124篇 |
矿业工程 | 2830篇 |
能源动力 | 12288篇 |
轻工业 | 30011篇 |
水利工程 | 4631篇 |
石油天然气 | 9550篇 |
武器工业 | 167篇 |
无线电 | 51607篇 |
一般工业技术 | 85836篇 |
冶金工业 | 76251篇 |
原子能技术 | 9421篇 |
自动化技术 | 35951篇 |
出版年
2022年 | 3263篇 |
2021年 | 4870篇 |
2020年 | 3758篇 |
2019年 | 4487篇 |
2018年 | 7267篇 |
2017年 | 7284篇 |
2016年 | 7611篇 |
2015年 | 5265篇 |
2014年 | 8256篇 |
2013年 | 21531篇 |
2012年 | 12870篇 |
2011年 | 16791篇 |
2010年 | 13501篇 |
2009年 | 14992篇 |
2008年 | 15279篇 |
2007年 | 14998篇 |
2006年 | 13673篇 |
2005年 | 12215篇 |
2004年 | 11165篇 |
2003年 | 11034篇 |
2002年 | 10381篇 |
2001年 | 10184篇 |
2000年 | 9648篇 |
1999年 | 10152篇 |
1998年 | 24854篇 |
1997年 | 17098篇 |
1996年 | 13181篇 |
1995年 | 9837篇 |
1994年 | 8628篇 |
1993年 | 8562篇 |
1992年 | 6204篇 |
1991年 | 5798篇 |
1990年 | 5764篇 |
1989年 | 5362篇 |
1988年 | 5106篇 |
1987年 | 4456篇 |
1986年 | 4324篇 |
1985年 | 4842篇 |
1984年 | 4448篇 |
1983年 | 4010篇 |
1982年 | 3666篇 |
1981年 | 3739篇 |
1980年 | 3442篇 |
1979年 | 3334篇 |
1978年 | 3337篇 |
1977年 | 3751篇 |
1976年 | 4849篇 |
1975年 | 2852篇 |
1974年 | 2664篇 |
1973年 | 2732篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Baizhan Li Chenqiu Du Hong Liu Wei Yu Jie Zheng Meilan Tan Zhenxing Jin Wenjie Li Jing Wu Lu Chen Runming Yao 《Indoor air》2019,29(2):308-319
The extensive research interests in environmental temperature can be linked to human productivity / performance as well as comfort and health; while the mechanisms of physiological indices responding to temperature variations remain incompletely understood. This study adopted a physiological sensory nerve conduction velocity (SCV) as a temperature‐sensitive biomarker to explore the thermoregulatory mechanisms of human responding to annual temperatures. The measurements of subjects’ SCV (over 600 samples) were conducted in a naturally ventilated environment over all four seasons. The results showed a positive correlation between SCV and annual temperatures and a Boltzmann model was adopted to depict the S‐shaped trend of SCV with operative temperatures from 5°C to 40°C. The SCV increased linearly with operative temperatures from 14.28°C to 20.5°C and responded sensitively for 10.19°C‐24.59°C, while tended to be stable beyond that. The subjects’ thermal sensations were linearly related to SCV, elaborating the relation between human physiological regulations and subjective thermal perception variations. The findings reveal the body SCV regulatory characteristics in different operative temperature intervals, thereby giving a deeper insight into human autonomic thermoregulation and benefiting for built environment designs, meantime minimizing the temperature‐invoked risks to human health and well‐being. 相似文献
62.
63.
64.
The 2011 AASHTO Roadside Design Guide (RDG) contains perhaps the most widely used procedure for choosing an appropriate length of need (LON) for roadside barriers. However, this procedure has several limitations. The procedure uses a highly simplified model of vehicle departure, and the procedure does not allow designers to specify an explicit level of protection. A new procedure for choosing LON that addresses these limitations is presented in this paper. This new procedure is based on recent, real-world road departure trajectories and uses this departure data in a more realistic way. The new procedure also allows LON to be specified for a precisely known level of protection – a level which can be based on number of crashes, injury outcomes or even estimated crash cost – while still remaining straightforward and quick to use like the 2011 RDG procedure. 相似文献
65.
66.
67.
68.
69.
70.