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   66篇
  免费   1篇
  国内免费   2篇
化学   61篇
数学   1篇
物理学   2篇
无线电   5篇
  2023年   1篇
  2019年   2篇
  2018年   2篇
  2017年   3篇
  2016年   2篇
  2014年   2篇
  2013年   4篇
  2012年   2篇
  2011年   4篇
  2010年   7篇
  2009年   6篇
  2008年   5篇
  2007年   6篇
  2006年   4篇
  2005年   3篇
  2004年   1篇
  2001年   2篇
  2000年   3篇
  1999年   1篇
  1998年   1篇
  1997年   2篇
  1996年   1篇
  1995年   1篇
  1993年   1篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
排序方式: 共有69条查询结果,搜索用时 31 毫秒
1.
2.
3.
4.
A proposed structure for the diffusible extracellular factor (DF) of Xanthomonas campestris pv. campestris (Xcc) has been synthesized. Its MS spectrum and biological activity, however, contradict those of the natural product previously reported, suggesting that the structure for DF of Xcc must be reexamined.  相似文献   
5.
6.
Community structure detection in complex networks has been intensively investigated in recent years. In this paper, we propose an adaptive approach based on ant colony clustering to discover communities in a complex network. The focus of the method is the clustering process of an ant colony in a virtual grid, where each ant represents a node in the complex network. During the ant colony search, the method uses a new fitness function to percept local environment and employs a pheromone diffusion model as a global information feedback mechanism to realize information exchange among ants. A significant advantage of our method is that the locations in the grid environment and the connections of the complex network structure are simultaneously taken into account in ants moving. Experimental results on computer-generated and real-world networks show the capability of our method to successfully detect community structures.  相似文献   
7.
In this work, we propose an improved alternative route calculation based on alternative figures, which is suitable for practical environments. The improvement is based on the fact that the main traffic route is the road network skeleton in a city. Our approach using nodes may generate a higher possibility of overlapping. We employ a bidirectional Dijkstra algorithm to search the route. To measure the quality of an Alternative Figures (AG), three quotas are proposed. The experiment results indicate that the improved algorithm proposed in this paper is more effective than others.  相似文献   
8.
The synthesis of (4R,9Z)-9-octadecen-4-olide 1, the female sex pheromone of Janus integer is reported using a Zipper isomerization reaction as the key step.  相似文献   
9.
10.
Kenji Mori 《Tetrahedron》2009,65(14):2798-699
All of the stereoisomers of the components of the female-produced sex pheromone of a moth, Lyclene dharma dharma, were synthesized. They are (R)- and (S)-6-methyl-2-octadecanone, (6R,14R)-, (6R,14S)-, (6S,14R)-, and (6S,14S)-6,14-dimethyl-2-octadecanone, and (R)- and (S)-14-methyl-2-octadecanone. Enantiomers of citronellal and methyl (S)-3-hydroxy-2-methylpropanoate were the starting materials, and olefin cross metathesis was employed as the key reaction.  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