首页 | 官方网站   微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   116113篇
  免费   11172篇
  国内免费   5987篇
工业技术   133272篇
  2024年   440篇
  2023年   2004篇
  2022年   3725篇
  2021年   5357篇
  2020年   4029篇
  2019年   3209篇
  2018年   3614篇
  2017年   3977篇
  2016年   3493篇
  2015年   4983篇
  2014年   6543篇
  2013年   7558篇
  2012年   8506篇
  2011年   8927篇
  2010年   8232篇
  2009年   7478篇
  2008年   7299篇
  2007年   7060篇
  2006年   6561篇
  2005年   5437篇
  2004年   3680篇
  2003年   2857篇
  2002年   2678篇
  2001年   2124篇
  2000年   2224篇
  1999年   2233篇
  1998年   1560篇
  1997年   1353篇
  1996年   1327篇
  1995年   1126篇
  1994年   878篇
  1993年   598篇
  1992年   477篇
  1991年   376篇
  1990年   289篇
  1989年   251篇
  1988年   216篇
  1987年   122篇
  1986年   103篇
  1985年   65篇
  1984年   66篇
  1983年   39篇
  1982年   37篇
  1981年   41篇
  1980年   36篇
  1979年   15篇
  1977年   12篇
  1976年   15篇
  1959年   8篇
  1951年   9篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
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   
73.
74.
Directionally solidified microstructures of Al2O3-Er3Al5O12 eutectic and off-eutectic in situ composite ceramics were explored under abrupt-change pulling rate conditions. Corresponding temperature distributions and interface locations were studied. In eutectic composition, fluctuation of eutectic spacing occurred when the pulling rate increased abruptly. A gradually increase or abrupt increase in eutectic spacing was observed when the pulling rate decreased abruptly. In hypoeutectic and hypereutectic compositions, formation of the primary phases were suppressed when the pulling rate increased abruptly from 10?µm/s to 100?µm/s, while primary phases precipitated when the pulling rate decreased abruptly from 100?µm/s to 10?µm/s. The interface altitude decreased after the pulling rate increased abruptly, but increased after the pulling rate decreased abruptly. The liquid composition restriction (around the eutectic composition) at the eutectic interface plays an important role in the suppression of the primary dendrite and coupled eutectic oxides can be obtained in off-eutectic compositions even under higher solidification rate conditions.  相似文献   
75.
76.
77.
Journal of Mechanical Science and Technology - Real-time monitoring and rapid evaluation of bearing operating conditions, especially for the reliability evaluation and remaining useful life (RUL)...  相似文献   
78.
79.
80.
Understanding semantic word shifts in scientific domains is essential for facilitating interdisciplinary communication. Using a data set of published papers in the field of information retrieval (IR), this paper studies the semantic shifts of words in IR based on mining per-word topic distribution over time. We propose that semantic word shifts not only occur over time, but also over topics. The shifts are examined from two perspectives, the topic-level and the context-level. According to the over-time word-topic distribution, stable words and unstable words are recognized. The diverging and converging trends in the unstable type reveal characteristics of the topic evolution process. The context-level shifts are further detected by similarities between word vectors. Our work associates semantic word shifts with the evolving of topics, which facilitates a better understanding of semantic word shifts from both topics and contexts.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号