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   661575篇
  免费   7847篇
  国内免费   2533篇
电工技术   12198篇
综合类   870篇
化学工业   95913篇
金属工艺   29506篇
机械仪表   22740篇
建筑科学   14529篇
矿业工程   3809篇
能源动力   17061篇
轻工业   46608篇
水利工程   7262篇
石油天然气   12948篇
武器工业   56篇
无线电   77990篇
一般工业技术   136063篇
冶金工业   119156篇
原子能技术   14981篇
自动化技术   60265篇
  2021年   5351篇
  2020年   4076篇
  2019年   5218篇
  2018年   14283篇
  2017年   14573篇
  2016年   12652篇
  2015年   6440篇
  2014年   10240篇
  2013年   28842篇
  2012年   18020篇
  2011年   27646篇
  2010年   22926篇
  2009年   24462篇
  2008年   24978篇
  2007年   26131篇
  2006年   18087篇
  2005年   18685篇
  2004年   17083篇
  2003年   16652篇
  2002年   15320篇
  2001年   14816篇
  2000年   14012篇
  1999年   14634篇
  1998年   37025篇
  1997年   25816篇
  1996年   19827篇
  1995年   14944篇
  1994年   13096篇
  1993年   13219篇
  1992年   9460篇
  1991年   8959篇
  1990年   8804篇
  1989年   8501篇
  1988年   8000篇
  1987年   7063篇
  1986年   7014篇
  1985年   7799篇
  1984年   7140篇
  1983年   6536篇
  1982年   6058篇
  1981年   6164篇
  1980年   5903篇
  1979年   5596篇
  1978年   5597篇
  1977年   6332篇
  1976年   8310篇
  1975年   4755篇
  1974年   4569篇
  1973年   4681篇
  1972年   3926篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Chemical and Petroleum Engineering - The hydrodynamics of oxidation towers used for bitumen production were studied using a model tower having transparent walls. Experiments were carried out in two...  相似文献   
42.
Journal of Engineering Physics and Thermophysics - A numerical investigation has been made into the interaction of slender (5–20 calibers) steel cylinder strikers with orthotropic compost...  相似文献   
43.
Journal of Engineering Physics and Thermophysics - Results of investigation into the influence of a corrosion process on thermotechnical characteristics of heat pipes of low-temperature range are...  相似文献   
44.
Deshmukh  P.  Sar  S. K.  Smječanin  N.  Nuhanović  M.  Lalwani  R. 《Radiochemistry》2022,64(4):532-542
Radiochemistry - Magnetically modified waste bark of the Aegle marmelos tree was prepared by using green synthesis method and was used in a batch system for U(VI) removal from aqueous solution. The...  相似文献   
45.
Kamar  M. S.  Shalan  A. S.  Youssef  W. M.  Hussein  A. E. M.  Khawassek  Y. M.  Taha  M. H. 《Radiochemistry》2022,64(2):244-256
Radiochemistry - Ferrugination, sericitization, desulfitization, chloritization, and kaolinitization of hydrothermal origin are the main wall rock alterations occurring within the NNW shear zones...  相似文献   
46.

Modern metrics for evaluating agreement coefficients between the experimental results and expert opinion are compared, and the possibility of using these metrics in experimental research in automatic text processing by machine learning methods is assessed. The choice of Cohen’s kappa coefficient as a measure of expert opinion agreement in the NLP and Text Mining problems is justified. An example of using Cohen’s kappa coefficient for evaluating the level of agreement between the opinion of an expert and the results of ML classification and the measure of agreement of expert opinions in the alignment of sentences of the Kazakh-Russian parallel corpus is given. Based on this analysis, it is proved that Cohen’s kappa coefficient is one of the best statistical methods for determining the level of agreement in experimental studies due to its ease of use, computing simplicity, and high accuracy of the results.

  相似文献   
47.
Extracellular vesicles (EVs) are membranous structures, which are secreted by almost every cell type analyzed so far. In addition to their importance for cell-cell communication under physiological conditions, EVs are also released during pathogenesis and mechanistically contribute to this process. Here we summarize their functional relevance in asthma, one of the most common chronic non-communicable diseases. Asthma is a complex persistent inflammatory disorder of the airways characterized by reversible airflow obstruction and, from a long-term perspective, airway remodeling. Overall, mechanistic studies summarized here indicate the importance of different subtypes of EVs and their variable cargoes in the functioning of the pathways underlying asthma, and show some interesting potential for the development of future therapeutic interventions. Association studies in turn demonstrate a good diagnostic potential of EVs in asthma.  相似文献   
48.
Wireless Personal Communications - Multiple inputs multiple outputs (MIMO) is a reliable technique which can manage the increased wireless data traffic in the future generation of wireless...  相似文献   
49.
Multimedia Tools and Applications - Discovering the relevant web services for specific applications in the dynamically changing business world becomes very critical. Researchers have used many...  相似文献   
50.
Mobile Networks and Applications - 5G/6G communication are first generation high speed wireless communication network which integrates the aerial data, terrestrial data and maritime data via...  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