首页 | 官方网站   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   2633篇
  免费   172篇
  国内免费   4篇
工业技术   2809篇
  2023年   45篇
  2022年   30篇
  2021年   161篇
  2020年   80篇
  2019年   76篇
  2018年   119篇
  2017年   69篇
  2016年   136篇
  2015年   92篇
  2014年   130篇
  2013年   210篇
  2012年   186篇
  2011年   237篇
  2010年   146篇
  2009年   151篇
  2008年   152篇
  2007年   130篇
  2006年   107篇
  2005年   81篇
  2004年   63篇
  2003年   56篇
  2002年   41篇
  2001年   23篇
  2000年   23篇
  1999年   22篇
  1998年   52篇
  1997年   37篇
  1996年   36篇
  1995年   18篇
  1994年   21篇
  1993年   12篇
  1992年   11篇
  1991年   3篇
  1990年   1篇
  1989年   8篇
  1988年   3篇
  1985年   4篇
  1984年   2篇
  1983年   3篇
  1982年   5篇
  1981年   2篇
  1980年   7篇
  1979年   4篇
  1977年   2篇
  1976年   3篇
  1975年   2篇
  1974年   3篇
  1972年   1篇
  1969年   1篇
  1965年   1篇
排序方式: 共有2809条查询结果,搜索用时 15 毫秒
11.
A series of 2-phenyloxazoles bearing an amide group at position 4 were designed and synthesized for evaluation as potential inhibitors of human recombinant monoamine oxidases (hrMAOs). Results of kinetics experiments demonstrated that all compounds behave as competitive MAO inhibitors, with good selectivity toward the MAO-B isoform. The most potent and selective derivatives are characterized by inhibition constant (Ki) values in the sub-micromolar range and a good selectivity index (Ki MAO-A/Ki MAO-B>50). Some derivatives were also found to be able to inhibit MAO activity in nerve growth factor (NGF)-differentiated PC12 cells, taken as a model of neuronal cells. In particular, 2-(2-hydroxyphenyl)-N-phenyloxazole-4-carboxamide (compound 4 a ) may be a promising new scaffold, exerting the highest selectivity and inhibitory effect toward MAOs in NGF-differentiated PC12 cell lysates, without compromising cell viability. Molecular docking analysis allowed a rationalization of the experimentally observed binding affinity and selectivity.  相似文献   
12.
Recently, investigations of the complex mechanisms of allostery have led to a deeper understanding of G protein-coupled receptor (GPCR) activation and signaling processes. In this context, muscarinic acetylcholine receptors (mAChRs) are highly relevant due to their exemplary role in the study of allosteric modulation. In this work, we compare and discuss two sets of putatively dualsteric ligands, which were designed to connect carbachol to different types of allosteric ligands. We chose derivatives of TBPB [1-(1′-(2-tolyl)-1,4′-bipiperidin-4-yl)-1H-benzo[d]imidazol-2(3H)-one] as M1-selective putative bitopic ligands, and derivatives of benzyl quinolone carboxylic acid (BQCA) as an M1 positive allosteric modulator, varying the distance between the allosteric and orthosteric building blocks. Luciferase protein complementation assays demonstrated that linker length must be carefully chosen to yield either agonist or antagonist behavior. These findings may help to design biased signaling and/or different extents of efficacy.  相似文献   
13.
The relevance of business model innovation (BMI) for strategic renewal and competitive advantage has been increasingly recognized by both strategy scholars and managers. In this paper, we explore how inter‐organizational networks and firms' proactiveness influence BMI. By examining Dutch design companies, we show that having a network of companies with different sizes has a positive effect on BMI. We also observe a positive effect of ties change. Finally, we show the importance of firms' proactiveness. Through the discussion of network elements and proactiveness as antecedents of BMI, we contribute to the business model and social network literature.  相似文献   
14.
Demand for honey is increasing, especially if it is organic and if its nutritional properties are linked to untreated environments in order to guarantee quality for health. Sources of contamination of honey can be divided into environmental and apicultural. Therefore, the distribution of persistent organic pollutants, pesticides and antibiotic residues from geographical areas with different contamination sources (high anthropic impact, intensive farming, husbandry and low anthropic impact) was investigated in order to confirm the potential transfer of xenobiotics into the supply chain and to give beekeepers tools for the selection of areas dedicated to organic production. The presence of polychlorinated biphenyls, polybrominated diphenyl ether and polycyclic aromatic hydrocarbons was confirmed, not only in proximity to highly urbanised centres, where the concentrations were higher, but in all environment contexts, confirming their ubiquity. No antibiotics or neonicotinoids were detected in 95 organic honeys, demonstrating the absence of apicultural treatments and consequently the good quality of honey of different areas. These results are important due to the undefined regulatory European situation on honey antibiotic limits.  相似文献   
15.
16.
17.
Graphene has been predicted to develop a magnetic moment by proximity effect when placed on a ferromagnetic film, a promise that could open exciting possibilities in the fields of spintronics and magnetic data recording. In this work, the interplay between the magnetoresistance of graphene and the magnetization of an underlying ferromagnetic insulating film is studied in detail. A clear correlation between both magnitudes is observed but through a careful modeling of the magnetization and the weak localization measurements, that such correspondence can be explained by the effects of the magnetic stray fields arising from the ferromagnetic insulator is found. The results emphasize the complexity arising at the interface between magnetic and 2D materials.  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-23

京公网安备 11010802026262号