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   104245篇
  免费   2374篇
  国内免费   463篇
电工技术   1064篇
综合类   2339篇
化学工业   16006篇
金属工艺   5514篇
机械仪表   4147篇
建筑科学   2560篇
矿业工程   565篇
能源动力   1980篇
轻工业   5465篇
水利工程   1353篇
石油天然气   358篇
无线电   12800篇
一般工业技术   20866篇
冶金工业   4096篇
原子能技术   543篇
自动化技术   27426篇
  2023年   274篇
  2022年   420篇
  2021年   719篇
  2020年   488篇
  2019年   518篇
  2018年   14958篇
  2017年   13876篇
  2016年   10612篇
  2015年   1226篇
  2014年   1185篇
  2013年   1606篇
  2012年   4551篇
  2011年   11022篇
  2010年   9420篇
  2009年   6784篇
  2008年   7873篇
  2007年   8610篇
  2006年   935篇
  2005年   1907篇
  2004年   1756篇
  2003年   1740篇
  2002年   1113篇
  2001年   610篇
  2000年   611篇
  1999年   478篇
  1998年   760篇
  1997年   450篇
  1996年   439篇
  1995年   266篇
  1994年   181篇
  1993年   159篇
  1992年   123篇
  1991年   122篇
  1990年   75篇
  1989年   88篇
  1988年   83篇
  1987年   63篇
  1986年   51篇
  1985年   43篇
  1984年   36篇
  1968年   45篇
  1967年   35篇
  1966年   44篇
  1965年   44篇
  1959年   35篇
  1958年   37篇
  1957年   36篇
  1956年   34篇
  1955年   63篇
  1954年   68篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Hepatic fibrosis occurs when liver tissue becomes scarred from repetitive liver injury and inflammatory responses; it can progress to cirrhosis and eventually to hepatocellular carcinoma. Previously, we reported that neoagarooligosaccharides (NAOs), produced by the hydrolysis of agar by β-agarases, have hepatoprotective effects against acetaminophen overdose-induced acute liver injury. However, the effect of NAOs on chronic liver injury, including hepatic fibrosis, has not yet been elucidated. Therefore, we examined whether NAOs protect against fibrogenesis in vitro and in vivo. NAOs ameliorated PAI-1, α-SMA, CTGF and fibronectin protein expression and decreased mRNA levels of fibrogenic genes in TGF-β-treated LX-2 cells. Furthermore, downstream of TGF-β, the Smad signaling pathway was inhibited by NAOs in LX-2 cells. Treatment with NAOs diminished the severity of hepatic injury, as evidenced by reduction in serum alanine aminotransferase and aspartate aminotransferase levels, in carbon tetrachloride (CCl4)-induced liver fibrosis mouse models. Moreover, NAOs markedly blocked histopathological changes and collagen accumulation, as shown by H&E and Sirius red staining, respectively. Finally, NAOs antagonized the CCl4-induced upregulation of the protein and mRNA levels of fibrogenic genes in the liver. In conclusion, our findings suggest that NAOs may be a promising candidate for the prevention and treatment of chronic liver injury via inhibition of the TGF-β/Smad signaling pathway.  相似文献   
2.
Food Science and Biotechnology - Various hilling materials (rice hulls, pine sawdust, and perlite) were compared to produce sprout vegetables using beach silvertop (Glehnia littoralis Fr. Schm. ex...  相似文献   
3.
International Journal of Information Security - Machine learning techniques have been widely used and shown remarkable performance in various fields. Along with the widespread utilization of...  相似文献   
4.
5.
6.
Food Science and Biotechnology - Aluminum based reflective nanolens arrays were developed via a series of aluminum electropolishing and anodization steps with subsequent selective dissolution of...  相似文献   
7.
8.
A series of anionic conjugated polyelectrolytes (CPEs) is synthesized based on poly(fluorene-co-phenylene) by varying the side-chain ionic density from two to six per repeat units (MPS2-TMA, MPS4-TMA, and MPS6-TMA). The effect of MPS2, 4, 6-TMA as interlayers on top of a hole-extraction layer of poly(bis(4-phenyl)-2,4,6-trimethylphenylamine (PTAA) is investigated in inverted perovskite solar cells (PeSCs). Owing to the improved wettability of perovskites on hydrophobic PTAA with the CPEs, the PeSCs with CPE interlayers demonstrate a significantly enhanced device performance, with negligible device-to-device dependence relative to the reference PeSC without CPEs. By increasing the ionic density in the MPS-TMA interlayers, the wetting, interfacial defect passivation, and crystal growth of the perovskites are significantly improved without increasing the series resistance of the PeSCs. In particular, the open-circuit voltage increases from 1.06 V for the PeSC with MPS2-TMA to 1.11 V for the PeSC with MPS6-TMA. The trap densities of the PeSCs with MPS2,4,6-TMA are further analyzed using frequency-dependent capacitance measurements. Finally, a large-area (1 cm2) PeSC is successfully fabricated with MPS6-TMA, showing a power conversion efficiency of 18.38% with negligible hysteresis and a stable power output under light soaking for 60 s.  相似文献   
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