首页 | 本学科首页   官方微博 | 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   128658篇
  免费   12627篇
  国内免费   7929篇
电工技术   9439篇
技术理论   5篇
综合类   11657篇
化学工业   18616篇
金属工艺   7480篇
机械仪表   8914篇
建筑科学   9589篇
矿业工程   3511篇
能源动力   3664篇
轻工业   10624篇
水利工程   3230篇
石油天然气   5642篇
武器工业   1367篇
无线电   15653篇
一般工业技术   12847篇
冶金工业   5043篇
原子能技术   1826篇
自动化技术   20107篇
  2024年   436篇
  2023年   1601篇
  2022年   3371篇
  2021年   4688篇
  2020年   3570篇
  2019年   2938篇
  2018年   3318篇
  2017年   3728篇
  2016年   3543篇
  2015年   5230篇
  2014年   6773篇
  2013年   8039篇
  2012年   9574篇
  2011年   10367篇
  2010年   9562篇
  2009年   9142篇
  2008年   9288篇
  2007年   8926篇
  2006年   8236篇
  2005年   6759篇
  2004年   5187篇
  2003年   4257篇
  2002年   4693篇
  2001年   4065篇
  2000年   2953篇
  1999年   2118篇
  1998年   1331篇
  1997年   1088篇
  1996年   965篇
  1995年   847篇
  1994年   622篇
  1993年   448篇
  1992年   361篇
  1991年   257篇
  1990年   215篇
  1989年   138篇
  1988年   128篇
  1987年   90篇
  1986年   42篇
  1985年   54篇
  1984年   38篇
  1983年   33篇
  1982年   21篇
  1981年   26篇
  1980年   34篇
  1979年   24篇
  1977年   13篇
  1976年   15篇
  1959年   14篇
  1951年   13篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
Recently, InE has been regarded as a popular education strategy in Chinese universities. However, problems have been exposed in the adoption of InE, for example, in InE courses and competitions. The purpose of this paper is to provide a possible solution to the problems, which is to organize effective InE courses by integrating InE with Inter-Course-level Problem-Based Learning (ICPBL). A detailed case is demonstrated by an ICPBL elective course design with deep integration of InE in the teaching, learning, and assessments. This paper contributes to a new curriculum design for promoting InE education in practically for Chinese universities.  相似文献   
52.
53.
锰粉料制块是解决铁合金冶炼精料入炉的主要途径之一,生产过程中为解决锰粉料粘附计量斗的问题,介绍了一种新型计量斗,阐述他的结构特点和工作原理,实施改进后下料流畅,降低了劳动强度,提高了生产效率。  相似文献   
54.
Zhang  Huawei  Yang  Zhi  Wu  Zhaoyu  Hong  Xiaoyu  Li  Zhong  Xu  Yulai  Li  Jun  Ni  Gaojin  Xiao  Xueshan 《Oxidation of Metals》2019,92(1-2):49-65
Oxidation of Metals - The isothermal oxidation behavior and oxide-scale evolution on a newly developed Ni–Fe-based superalloy were investigated. Three oxidation stages were generally...  相似文献   
55.
56.
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   
57.
利用猪毛、风化煤和腐植酸钠的水解液为增效剂制备了一种增效过磷酸钙,探讨了增效过磷酸钙的增效机制及其对玉米生长的影响。结果表明,蒸馏水浸提条件下,增效过磷酸钙能减缓水溶磷的释放,具备较高的pH值缓冲性。与普通过磷酸钙相比,增效过磷酸钙处理的玉米生物量平均增加了41.9%,吸磷量和吸钙量分别增加了61.7%和27.8%,根系活力增加了24.3%。该研究结果对过磷酸钙生产的技术改进具有指导意义。  相似文献   
58.
59.
Rapid and sensitive point-of-care testing (POCT) is an extremely critical mission in practical applications, especially for rigorous military medicine, home health care, and in the third world. Here, we report a visual POCT method for adenosine triphosphate (ATP) detection based on Taylor rising in the corner of quadratic geometries between two rod surfaces. We discuss the principle of Taylor rising, demonstrating that it is significantly influenced by contact angle, surface tension, and density of the sample, which are controlled by ATP-dependent rolling circle amplification (RCA). In the presence of ATP, RCA reaction effectively suppresses Taylor-rising behavior, due to the increased contact angle, density, and decreased surface tension. Without addition of ATP, untriggered RCA reaction is favorable for Taylor rising, resulting in a significant height. With this proposed method, visual sensitive detection of ATP without the aid of other instruments is realized with only a 5 μL droplet, which has good selectivity and a low detection limit (17 nM). Importantly, this visual method provides a promising POCT tool for user-friendly molecular diagnostics.  相似文献   
60.
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