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   58193篇
  免费   4718篇
  国内免费   2587篇
电工技术   3593篇
技术理论   3篇
综合类   3966篇
化学工业   9636篇
金属工艺   3352篇
机械仪表   3834篇
建筑科学   4569篇
矿业工程   1831篇
能源动力   1684篇
轻工业   3806篇
水利工程   1043篇
石油天然气   3964篇
武器工业   525篇
无线电   6292篇
一般工业技术   6971篇
冶金工业   2626篇
原子能技术   583篇
自动化技术   7220篇
  2024年   264篇
  2023年   1042篇
  2022年   1773篇
  2021年   2434篇
  2020年   1954篇
  2019年   1574篇
  2018年   1737篇
  2017年   1934篇
  2016年   1669篇
  2015年   2292篇
  2014年   2966篇
  2013年   3311篇
  2012年   3596篇
  2011年   4056篇
  2010年   3502篇
  2009年   3288篇
  2008年   3220篇
  2007年   2986篇
  2006年   3082篇
  2005年   2575篇
  2004年   1844篇
  2003年   1634篇
  2002年   1611篇
  2001年   1394篇
  2000年   1297篇
  1999年   1530篇
  1998年   1286篇
  1997年   1123篇
  1996年   1005篇
  1995年   830篇
  1994年   667篇
  1993年   482篇
  1992年   422篇
  1991年   265篇
  1990年   213篇
  1989年   166篇
  1988年   122篇
  1987年   84篇
  1986年   69篇
  1985年   44篇
  1984年   35篇
  1983年   32篇
  1982年   31篇
  1981年   19篇
  1980年   17篇
  1979年   6篇
  1940年   3篇
  1933年   1篇
  1929年   1篇
  1928年   1篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
102.
Radiotherapy is identified as a crucial treatment for patients with glioblastoma, but recurrence is inevitable. The efficacy of radiotherapy is severely hampered partially due to the tumor evolution. Growing evidence suggests that proneural glioma stem cells can acquire mesenchymal features coupled with increased radioresistance. Thus, a better understanding of mechanisms underlying tumor subclonal evolution may develop new strategies. Herein, data highlighting a positive correlation between the accumulation of macrophage in the glioblastoma microenvironment after irradiation and mesenchymal transdifferentiation in glioblastoma are presented. Mechanistically, elevated production of inflammatory cytokines released by macrophages promotes mesenchymal transition in an NF-κB-dependent manner. Hence, rationally designed macrophage membrane-coated porous mesoporous silica nanoparticles (MMNs) in which therapeutic anti-NF-κB peptides are loaded for enhancing radiotherapy of glioblastoma are constructed. The combination of MMNs and fractionated irradiation results in the blockage of tumor evolution and therapy resistance in glioblastoma-bearing mice. Intriguingly, the macrophage invasion across the blood-brain barrier is inhibited competitively by MMNs, suggesting that these nanoparticles can fundamentally halt the evolution of radioresistant clones. Taken together, the biomimetic MMNs represent a promising strategy that prevents mesenchymal transition and improves therapeutic response to irradiation as well as overall survival in patients with glioblastoma.  相似文献   
103.
Yang  Lu  Jiang  He  Song  Qing  Guo  Jun 《International Journal of Computer Vision》2022,130(7):1837-1872

The heavy reliance on data is one of the major reasons that currently limit the development of deep learning. Data quality directly dominates the effect of deep learning models, and the long-tailed distribution is one of the factors affecting data quality. The long-tailed phenomenon is prevalent due to the prevalence of power law in nature. In this case, the performance of deep learning models is often dominated by the head classes while the learning of the tail classes is severely underdeveloped. In order to learn adequately for all classes, many researchers have studied and preliminarily addressed the long-tailed problem. In this survey, we focus on the problems caused by long-tailed data distribution, sort out the representative long-tailed visual recognition datasets and summarize some mainstream long-tailed studies. Specifically, we summarize these studies into ten categories from the perspective of representation learning, and outline the highlights and limitations of each category. Besides, we have studied four quantitative metrics for evaluating the imbalance, and suggest using the Gini coefficient to evaluate the long-tailedness of a dataset. Based on the Gini coefficient, we quantitatively study 20 widely-used and large-scale visual datasets proposed in the last decade, and find that the long-tailed phenomenon is widespread and has not been fully studied. Finally, we provide several future directions for the development of long-tailed learning to provide more ideas for readers.

  相似文献   
104.
105.
106.
107.
108.
109.
The capability to study the dynamic formation of plasmonic molecular junction is of fundamental importance, and it will provide new insights into molecular electronics/plasmonics, single‐entity electrochemistry, and nanooptoelectronics. Here, a facile method to form plasmonic molecular junctions is reported by utilizing single gold nanoparticle (NP) collision events at a highly curved gold nanoelectrode modified with a self‐assembled monolayer. By using time‐resolved electrochemical current measurement and surface‐enhanced Raman scattering spectroscopy, the current changes and the evolution of interfacial chemical bonding are successfully observed in the newly formed molecular tunnel junctions during and after the gold NP “hit‐n‐stay” and “hit‐n‐run” collision events. The results lead to an in‐depth understanding of the single NP motion and the associated molecular level changes during the formation of the plasmonic molecular junctions in a single NP collision event. This method also provides a new platform to study molecular changes at the single molecule level during electron transport in a dynamic molecular tunnel junction.  相似文献   
110.
Meng  Fanbin  Wang  Ying  Wang  Qiang  Xu  Xiaoling  Jiang  Man  Zhou  Xuesong  He  Ping  Zhou  Zuowan 《Nano Research》2018,11(7):3958-3958
Nano Research - The first author, Fanbin Meng, and the second author, Ying Wang, contributed equally to this work was unfortunately forgotten to write on the first pages of the main text and the...  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