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   8747篇
  免费   484篇
  国内免费   15篇
电工技术   91篇
综合类   7篇
化学工业   2148篇
金属工艺   189篇
机械仪表   179篇
建筑科学   343篇
矿业工程   21篇
能源动力   266篇
轻工业   884篇
水利工程   91篇
石油天然气   30篇
武器工业   6篇
无线电   668篇
一般工业技术   1760篇
冶金工业   1030篇
原子能技术   55篇
自动化技术   1478篇
  2023年   60篇
  2022年   123篇
  2021年   178篇
  2020年   174篇
  2019年   142篇
  2018年   195篇
  2017年   212篇
  2016年   280篇
  2015年   182篇
  2014年   295篇
  2013年   663篇
  2012年   485篇
  2011年   598篇
  2010年   414篇
  2009年   406篇
  2008年   554篇
  2007年   473篇
  2006年   407篇
  2005年   330篇
  2004年   304篇
  2003年   275篇
  2002年   220篇
  2001年   148篇
  2000年   121篇
  1999年   133篇
  1998年   174篇
  1997年   144篇
  1996年   140篇
  1995年   120篇
  1994年   146篇
  1993年   106篇
  1992年   82篇
  1991年   65篇
  1990年   60篇
  1989年   85篇
  1988年   55篇
  1987年   36篇
  1986年   46篇
  1985年   53篇
  1984年   57篇
  1983年   32篇
  1982年   33篇
  1981年   53篇
  1980年   36篇
  1979年   31篇
  1978年   41篇
  1977年   25篇
  1976年   36篇
  1975年   20篇
  1974年   31篇
排序方式: 共有9246条查询结果,搜索用时 46 毫秒
1.
Journal of Materials Science - For transformers and inductors to meet the world’s growing demand for electrical power, more efficient soft magnetic materials with high saturation magnetic...  相似文献   
2.
Multimedia Tools and Applications - Changes in appearance present a tremendous problem for the visual localization of an autonomous vehicle in outdoor environments. Data association between the...  相似文献   
3.
Treating neuroinflammation-related injuries and disorders through manipulation of neuroinflammation functions is being heralded as a new therapeutic strategy. In this study, a novel pectic galactan (PG) polysaccharide based gene therapy approach is developed for targeting reactive gliosis in neuroinflammation. Galectin-3 (Gal-3) is a cell protein with a high affinity to β-galactoside sugars and is highly expressed in reactive gliosis. Since PG carries galactans, it can target reactive gliosis via specific carbohydrate interaction between galactan and Gal-3 on the cell membrane, and therefore can be utilized as a carrier for delivering genes to these cells. The carrier is synthesized by modifying quaternary ammonium groups on the PG. The resulting quaternized PG (QPG) is found to form complexes with plasmid DNA with a mean diameter of 100 nm and have the characteristics required for targeted gene therapy. The complexes efficiently condense large amounts of plasmid per particle and successfully bind to Gal-3. The in vivo study shows that the complexes are biocompatible and safe for administration and can selectively transfect reactive glial cells of an induced cortical lesion. The results confirm that this PG-based delivery system is a promising platform for targeting Gal-3 overexpressing neuroinflammation cells for treating neuroinflammation-related injuries and neurodegenerative diseases.  相似文献   
4.
Fischer-Tropsch synthesis of the CO2 in biogas aims at producing light hydrocarbons and increasing its calorific value for feeding into the grid. Fe catalysts with Mn and K as promoters are supposed to yield high amounts of light hydrocarbons. Using a Fe-Mn-K/MgO catalyst, a parameter screening and long-term experiments were carried out. The catalyst shows, within the examined range, the highest selectivity to C2–C4 hydrocarbons at 450 °C, 8 bar(a), and a gas hourly space velocity of 350 h−1. Calcination of the catalyst resulted in a significant drop of activity and an almost complete loss of selectivity to hydrocarbons. Admixture of steam to the reactant gas lowers the tendency to carbon deposition but also promotes the water-gas shift reaction and results in lower yields of hydrocarbons.  相似文献   
5.
6.
7.
Bile acids have been reported as important cofactors promoting human and murine norovirus (NoV) infections in cell culture. The underlying mechanisms are not resolved. Through the use of chemical shift perturbation (CSP) NMR experiments, we identified a low-affinity bile acid binding site of a human GII.4 NoV strain. Long-timescale MD simulations reveal the formation of a ligand-accessible binding pocket of flexible shape, allowing the formation of stable viral coat protein–bile acid complexes in agreement with experimental CSP data. CSP NMR experiments also show that this mode of bile acid binding has a minor influence on the binding of histo-blood group antigens and vice versa. STD NMR experiments probing the binding of bile acids to virus-like particles of seven different strains suggest that low-affinity bile acid binding is a common feature of human NoV and should therefore be important for understanding the role of bile acids as cofactors in NoV infection.  相似文献   
8.
9.
10.
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