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   5629篇
  免费   253篇
  国内免费   2篇
电工技术   5篇
综合类   4篇
化学工业   611篇
金属工艺   50篇
机械仪表   70篇
建筑科学   24篇
能源动力   51篇
轻工业   404篇
水利工程   3篇
石油天然气   2篇
无线电   253篇
一般工业技术   405篇
冶金工业   3845篇
原子能技术   9篇
自动化技术   148篇
  2023年   32篇
  2022年   15篇
  2021年   119篇
  2020年   68篇
  2019年   75篇
  2018年   84篇
  2017年   98篇
  2016年   109篇
  2015年   94篇
  2014年   137篇
  2013年   126篇
  2012年   149篇
  2011年   184篇
  2010年   145篇
  2009年   111篇
  2008年   104篇
  2007年   72篇
  2006年   55篇
  2005年   62篇
  2004年   51篇
  2003年   42篇
  2002年   24篇
  2001年   15篇
  2000年   15篇
  1999年   145篇
  1998年   1221篇
  1997年   684篇
  1996年   425篇
  1995年   223篇
  1994年   190篇
  1993年   250篇
  1992年   29篇
  1991年   50篇
  1990年   49篇
  1989年   62篇
  1988年   64篇
  1987年   53篇
  1986年   37篇
  1985年   35篇
  1983年   8篇
  1982年   17篇
  1981年   21篇
  1980年   20篇
  1979年   2篇
  1978年   8篇
  1977年   96篇
  1976年   196篇
  1975年   9篇
  1970年   1篇
  1955年   1篇
排序方式: 共有5884条查询结果,搜索用时 15 毫秒
1.
2.
3.
Evaluation of kinetic distribution and behaviors of nanoparticles in vivo provides crucial clues into their roles in living organisms. Extracellular vesicles are evolutionary conserved nanoparticles, known to play important biological functions in intercellular, inter‐species, and inter‐kingdom communication. In this study, the first kinetic analysis of the biodistribution of outer membrane vesicles (OMVs)—bacterial extracellular vesicles—with immune‐modulatory functions is performed. OMVs, injected intraperitoneally, spread to the whole mouse body and accumulate in the liver, lung, spleen, and kidney within 3 h of administration. As an early systemic inflammation response, increased levels of TNF‐α and IL‐6 are observed in serum and bronchoalveolar lavage fluid. In addition, the number of leukocytes and platelets in the blood is decreased. OMVs and cytokine concentrations, as well as body temperature are gradually decreased 6 h after OMV injection, in concomitance with the formation of eye exudates, and of an increase in ICAM‐1 levels in the lung. Following OMV elimination, most of the inflammatory signs are reverted, 12 h post‐injection. However, leukocytes in bronchoalveolar lavage fluid are increased as a late reaction. Taken together, these results suggest that OMVs are effective mediators of long distance communication in vivo.  相似文献   
4.
5.
6.
7.
Chun  Dong Hyun  Rhim  Geun Bae  Youn  Min Hye  Deviana  Deviana  Lee  Ji Eun  Park  Ji Chan  Jeong  Heondo 《Topics in Catalysis》2020,63(9-10):793-809
Topics in Catalysis - Fischer–Tropsch synthesis (FTS) is a promising way to produce clean liquid fuels and high value-added chemicals from low-value carbon-containing resources such as coal,...  相似文献   
8.
Vegetable soup (VS), a plant-based functional food, has been used as a traditional folk medicine and is attracting attention for its ability to enhance the immune response. β-Glucan, a well-established and effective immunomodulator, has synergistic effects when used in combination with some bioactive compounds. In the present study, we aimed to evaluate the synergistic immunomodulatory effects of the combination of VS and β-glucan on macrophage-mediated immune responses. β-Glucan was demonstrated to synergistically enhance the VS-stimulated immune response, including the production of interleukin-6, tumor necrosis factor-α, and nitric oxide, mainly through the mitogen-activated protein kinase pathway in macrophages. In addition, this combination has the potential for further development in functional foods with immune-enhancing activity.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10068-021-00888-x.  相似文献   
9.
The aim of this study was to assess the association between the length of maternity leave and the quality of mother-infant interactions; 198 employed mothers of 4-month-old infants were interviewed and videotaped in their homes during a feeding time. Hierarchical multiple regression analyses indicated a direct association between shorter length of leave and more negative affect and behavior in maternal interactions with their infants. Infant and mother stressor/protective variables added significantly in predicting the quality of the mother-infant relationship. There were also significant interaction effects between the length of leave and these variables. Mothers who either reported more depressive symptoms or who perceived their infant as having a more difficult temperament and who had shorter leaves, compared with mothers who had longer leaves, were observed to express less positive affect, sensitivity, and responsiveness in interactions with their infants. The public policy implications of the relation between length of maternity leave, maternal and infant individual differences, and the quality of mother-infant interactions are discussed.  相似文献   
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