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   15372篇
  免费   554篇
  国内免费   15篇
电工技术   219篇
综合类   6篇
化学工业   2703篇
金属工艺   283篇
机械仪表   284篇
建筑科学   442篇
矿业工程   45篇
能源动力   346篇
轻工业   1388篇
水利工程   116篇
石油天然气   50篇
武器工业   6篇
无线电   1335篇
一般工业技术   2541篇
冶金工业   3945篇
原子能技术   152篇
自动化技术   2080篇
  2023年   68篇
  2022年   142篇
  2021年   209篇
  2020年   191篇
  2019年   178篇
  2018年   230篇
  2017年   251篇
  2016年   322篇
  2015年   216篇
  2014年   351篇
  2013年   786篇
  2012年   606篇
  2011年   765篇
  2010年   561篇
  2009年   572篇
  2008年   722篇
  2007年   649篇
  2006年   563篇
  2005年   500篇
  2004年   464篇
  2003年   399篇
  2002年   343篇
  2001年   270篇
  2000年   263篇
  1999年   319篇
  1998年   856篇
  1997年   556篇
  1996年   475篇
  1995年   322篇
  1994年   322篇
  1993年   342篇
  1992年   210篇
  1991年   196篇
  1990年   186篇
  1989年   220篇
  1988年   189篇
  1987年   140篇
  1986年   167篇
  1985年   160篇
  1984年   126篇
  1983年   114篇
  1982年   104篇
  1981年   106篇
  1980年   91篇
  1979年   100篇
  1978年   103篇
  1977年   124篇
  1976年   187篇
  1975年   69篇
  1974年   77篇
排序方式: 共有10000条查询结果,搜索用时 31 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.
5.
6.
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   
7.
8.
9.
A sizable part (~2%) of the human genome encodes for proteases. They are involved in many physiological processes, such as development, reproduction and inflammation, but also play a role in pathology. Mast cells (MC) contain a variety of MC specific proteases, the expression of which may differ between various MC subtypes. Amongst these proteases, chymase represents up to 25% of the total proteins in the MC and is released from cytoplasmic granules upon activation. Once secreted, it cleaves the targets in the local tissue environment, but may also act in lymph nodes infiltrated by MC, or systemically, when reaching the circulation during an inflammatory response. MC have been recognized as important components in the development of kidney disease. Based on this observation, MC chymase has gained interest following the discovery that it contributes to the angiotensin-converting enzyme’s independent generation of angiotensin II, an important inflammatory mediator in the development of kidney disease. Hence, progress regarding its role has been made based on studies using inhibitors but also on mice deficient in MC protease 4 (mMCP-4), the functional murine counterpart of human chymase. In this review, we discuss the role and actions of chymase in kidney disease. While initially believed to contribute to pathogenesis, the accumulated data favor a more subtle view, indicating that chymase may also have beneficial actions.  相似文献   
10.
Perfluorocarbons, saturated carbon chains in which all the hydrogen atoms are replaced with fluorine, form a separate phase from both organic and aqueous solutions. Though perfluorinated compounds are not found in living systems, they can be used to modify biomolecules to confer orthogonal behavior within natural systems, such as improved stability, engineered assembly, and cell-permeability. Perfluorinated groups also provide handles for purification, mass spectrometry, and 19F NMR studies in complex environments. Herein, we describe how the unique properties of perfluorocarbons have been employed to understand and manipulate biological systems.  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