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   35635篇
  免费   1650篇
  国内免费   124篇
电工技术   456篇
综合类   230篇
化学工业   6886篇
金属工艺   794篇
机械仪表   726篇
建筑科学   1236篇
矿业工程   106篇
能源动力   1172篇
轻工业   4528篇
水利工程   315篇
石油天然气   177篇
武器工业   12篇
无线电   2780篇
一般工业技术   5630篇
冶金工业   7035篇
原子能技术   280篇
自动化技术   5046篇
  2023年   204篇
  2022年   609篇
  2021年   941篇
  2020年   682篇
  2019年   727篇
  2018年   859篇
  2017年   953篇
  2016年   959篇
  2015年   711篇
  2014年   1112篇
  2013年   1996篇
  2012年   1682篇
  2011年   2107篇
  2010年   1511篇
  2009年   1562篇
  2008年   1580篇
  2007年   1375篇
  2006年   1132篇
  2005年   1132篇
  2004年   1173篇
  2003年   1044篇
  2002年   986篇
  2001年   810篇
  2000年   637篇
  1999年   634篇
  1998年   2138篇
  1997年   1418篇
  1996年   1018篇
  1995年   690篇
  1994年   577篇
  1993年   606篇
  1992年   278篇
  1991年   331篇
  1990年   267篇
  1989年   251篇
  1988年   252篇
  1987年   181篇
  1986年   194篇
  1985年   218篇
  1984年   168篇
  1983年   116篇
  1982年   142篇
  1981年   161篇
  1980年   137篇
  1979年   112篇
  1978年   98篇
  1977年   152篇
  1976年   234篇
  1975年   93篇
  1973年   63篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
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   
12.
Alcohol-free beer with isotonic properties is getting more popular and its production can be carried out by different production strategies; however, interrupted fermentation is still a challenge. Therefore, the objective of this study was to develop a low-alcohol isotonic beer (<0.5% v/v) by interrupted fermentation. Moreover, the major objective is to compare the developed product to commercial beverages (sports drinks, ‘Pilsen' regular beer, alcohol-free beers and low-alcohol isotonic beer). The beverages were evaluated based on pH, alcohol content (% v/v), total titratable acidity (mEq L−1), osmolality (mOsmol kg−1), bitterness International Bitterness Units, colour European Brewery Convention, total phenolic compounds (mg L−1 gallic acid), reducing and total sugars (%) and Na and K contents (mg L−1). The developed low-alcohol isotonic beer presented characteristics similar to sports drinks, with the advantage of being richer in phenolic compounds and suitable osmolality. Despite salts were added in its formulation, the grades attributed to all beers employed in the sensory evaluation, as well as the purchase intention did not present significant differences.  相似文献   
13.
14.
15.
16.
Here we report some recent biophysical issues on the preparation of solute-filled lipid vesicles and their relevance to the construction of “synthetic cells.” First, we introduce the “semi-synthetic minimal cells” as the liposome-based cell-like systems, which contain a minimal number of biomolecules required to display simple and complex biological functions. Next, we focus on recent aspects related to the construction of synthetic cells. Emphasis is given to the interplay between the methods of synthetic cell preparation and the physics of solute encapsulation. We briefly introduce the notion of structural and compositional “diversity” in synthetic cell populations.  相似文献   
17.
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   
18.
19.
20.
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