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   5篇
  免费   0篇
现状及发展   1篇
研究方法   1篇
综合类   3篇
  2008年   2篇
  2007年   1篇
  2005年   1篇
  1980年   1篇
排序方式: 共有5条查询结果,搜索用时 15 毫秒
1
1.
Summary (–)--Fenchol, a compound occurring in plants but not heretofore reported to occur in an animal product, was isolated from volatiles released by adult male Mediterranean fruit flies,Ceratitis capitata Wiedemann, with the male's previously identified sex pheromones. It neither attracts females nor synergizes the pheromones, and its function remains unknown.The editors do not hold themselves responsible for the opinions expressed in the authors' brief reports. — Les auteurs sont seuls responsables des opinions exprimées dans ces brèves communications. — Für die Kurzmitteilungen ist ausschliesslich der Autor verantwortlich.—Per le brevi comunicazioni è responsabile solo l'autore. — . — Solo los autores son responsables de las opiniones expresadas en estas communicationes breves.Mention of a proprietary product in this paper does not constitute a recommendation or an endorsement of the product by the US Department of Agriculture.Acknowledgments. We thank C. Harding for assistance with extractions and fractionations, R.M. Waters for spectral analyses, M.S. Fujimoto and H. Higa for collecting the volatiles and conducting laboratory and cage bioassays, and T. Urago and S. Nakagawa for conducting the field tests.  相似文献   
2.
Neuroblastoma in advanced stages is one of the most intractable paediatric cancers, even with recent therapeutic advances. Neuroblastoma harbours a variety of genetic changes, including a high frequency of MYCN amplification, loss of heterozygosity at 1p36 and 11q, and gain of genetic material from 17q, all of which have been implicated in the pathogenesis of neuroblastoma. However, the scarcity of reliable molecular targets has hampered the development of effective therapeutic agents targeting neuroblastoma. Here we show that the anaplastic lymphoma kinase (ALK), originally identified as a fusion kinase in a subtype of non-Hodgkin's lymphoma (NPM-ALK) and more recently in adenocarcinoma of lung (EML4-ALK), is also a frequent target of genetic alteration in advanced neuroblastoma. According to our genome-wide scans of genetic lesions in 215 primary neuroblastoma samples using high-density single-nucleotide polymorphism genotyping microarrays, the ALK locus, centromeric to the MYCN locus, was identified as a recurrent target of copy number gain and gene amplification. Furthermore, DNA sequencing of ALK revealed eight novel missense mutations in 13 out of 215 (6.1%) fresh tumours and 8 out of 24 (33%) neuroblastoma-derived cell lines. All but one mutation in the primary samples (12 out of 13) were found in stages 3-4 of the disease and were harboured in the kinase domain. The mutated kinases were autophosphorylated and displayed increased kinase activity compared with the wild-type kinase. They were able to transform NIH3T3 fibroblasts as shown by their colony formation ability in soft agar and their capacity to form tumours in nude mice. Furthermore, we demonstrate that downregulation of ALK through RNA interference suppresses proliferation of neuroblastoma cells harbouring mutated ALK. We anticipate that our findings will provide new insights into the pathogenesis of advanced neuroblastoma and that ALK-specific kinase inhibitors might improve its clinical outcome.  相似文献   
3.
Controlling a phase of matter by coherently manipulating specific vibrational modes has long been an attractive (yet elusive) goal for ultrafast science. Solids with strongly correlated electrons, in which even subtle crystallographic distortions can result in colossal changes of the electronic and magnetic properties, could be directed between competing phases by such selective vibrational excitation. In this way, the dynamics of the electronic ground state of the system become accessible, and new insight into the underlying physics might be gained. Here we report the ultrafast switching of the electronic phase of a magnetoresistive manganite via direct excitation of a phonon mode at 71 meV (17 THz). A prompt, five-order-of-magnitude drop in resistivity is observed, associated with a non-equilibrium transition from the stable insulating phase to a metastable metallic phase. In contrast with light-induced and current-driven phase transitions, the vibrationally driven bandgap collapse observed here is not related to hot-carrier injection and is uniquely attributed to a large-amplitude Mn-O distortion. This corresponds to a perturbation of the perovskite-structure tolerance factor, which in turn controls the electronic bandwidth via inter-site orbital overlap. Phase control by coherent manipulation of selected metal-oxygen phonons should find extensive application in other complex solids--notably in copper oxide superconductors, in which the role of Cu-O vibrations on the electronic properties is currently controversial.  相似文献   
4.
5.
1
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