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   58篇
  免费   0篇
系统科学   1篇
现状及发展   15篇
研究方法   1篇
综合类   40篇
自然研究   1篇
  2013年   1篇
  2012年   1篇
  2011年   5篇
  2010年   1篇
  2009年   1篇
  2008年   1篇
  2006年   1篇
  2003年   2篇
  2002年   1篇
  2001年   3篇
  2000年   4篇
  1999年   1篇
  1998年   1篇
  1992年   1篇
  1990年   1篇
  1989年   2篇
  1988年   2篇
  1987年   3篇
  1985年   1篇
  1984年   2篇
  1980年   1篇
  1978年   1篇
  1977年   1篇
  1975年   2篇
  1972年   1篇
  1971年   4篇
  1970年   1篇
  1969年   1篇
  1968年   3篇
  1967年   2篇
  1965年   2篇
  1964年   2篇
  1959年   2篇
排序方式: 共有58条查询结果,搜索用时 15 毫秒
41.
42.
Zusammenfassung Pathologische Veränderungen bei Kaninchen, Hunden und Affen nach intrazysternaler Verabreichung von Bakterienendotoxinen sind einander sehr ähnlich, während sie nach i.v. Injektion bei allen 3 Tiergruppen auffallend verschieden sind. Dies führt zur Annahme, dass die Wirkung des Endotoxins zur Hauptsache offenbar nicht über das Zentralnervensystem geht.  相似文献   
43.
Zusammenfassung Lebergewebeschnitte mit Cumarin antikoagulentienvorbehandelter Ratten zeigen den Faktor VII im Medium nur beim Zusatz von Vitamin K. Die Vitamin-K-Wirkung wird bei gleichzeitigem Zusatz von Aktinomycin D nicht beeinflusst. Diese Beobachtung stimmt nicht überein mit der Hypothese, dass Vitamin K durch Beförderung der Auslösung der für die Synthese des Faktors VII spezifischen t-RNA eine Wirkung ausübt.  相似文献   
44.
Plastids of the Venus flytrap (Dionaea muscipula)   总被引:2,自引:0,他引:2  
J Scala  D W Schwab  E Simmons 《Nature》1968,219(5159):1183-1184
  相似文献   
45.
Simmons RM 《Nature》2000,407(6806):839
  相似文献   
46.
Proposed mechanism of force generation in striated muscle   总被引:160,自引:0,他引:160  
A F Huxley  R M Simmons 《Nature》1971,233(5321):533-538
  相似文献   
47.
48.
Hypovolemic shock (dengue shock syndrome (DSS)) is the most common life-threatening complication of dengue. We conducted a genome-wide association study of 2,008 pediatric cases treated for DSS and 2,018 controls from Vietnam. Replication of the most significantly associated markers was carried out in an independent Vietnamese sample of 1,737 cases and 2,934 controls. SNPs at two loci showed genome-wide significant association with DSS. We identified a susceptibility locus at MICB (major histocompatibility complex (MHC) class I polypeptide-related sequence B), which was within the broad MHC region on chromosome 6 but outside the class I and class II HLA loci (rs3132468, P(meta) = 4.41 × 10(-11), per-allele odds ratio (OR) = 1.34 (95% confidence interval: 1.23-1.46)). We identified associated variants within PLCE1 (phospholipase C, epsilon 1) on chromosome 10 (rs3765524, P(meta) = 3.08 × 10(-10), per-allele OR = 0.80 (95% confidence interval: 0.75-0.86)). We identify two loci associated with susceptibility to DSS in people with dengue, suggesting possible mechanisms for this severe complication of dengue.  相似文献   
49.
Approaches to efficiency in manufacturing and assem bl y over the past 100 years have concentrated frequently on the twin themes of div iding jobs done by people into defined segments and to automating as many of tho se segments as possible. This approach to manufacturing engineering may be char acterised as one of deconstruction and replacement so far as the role of the hum an being is concerned. More recently design engineering has been approached in a similar light with research into ‘intelligent‘ met...  相似文献   
50.
Simmons EM  Hartwig JF 《Nature》2012,483(7387):70-73
New synthetic methods for the catalytic functionalization of C-H bonds have the potential to revolutionize the synthesis of complex molecules. However, the realization of this synthetic potential requires the ability to functionalize selectively one C-H bond in a compound containing many such bonds and an array of functional groups. The site-selective functionalization of aliphatic C-H bonds is one of the greatest challenges that must be met for C-H bond functionalization to be used widely in complex-molecule synthesis, and processes catalysed by transition-metals provide the opportunity to control selectivity. Current methods for catalytic, aliphatic C-H bond functionalization typically rely on the presence of one inherently reactive C-H bond, or on installation and subsequent removal of directing groups that are not components of the desired molecule. To overcome these limitations, we sought catalysts and reagents that would facilitate aliphatic C-H bond functionalization at a single site, with chemoselectivity derived from the properties of the catalyst and site-selectivity directed by common functional groups contained in both the reactant and the desired product. Here we show that the combination of an iridium-phenanthroline catalyst and a dihydridosilane reagent leads to the site-selective γ-functionalization of primary C-H bonds controlled by a hydroxyl group, the most common functional group in natural products. The scope of the reaction encompasses alcohols and ketones bearing many substitution patterns and auxiliary functional groups; this broad scope suggests that this methodology will be suitable for the site-selective and diastereoselective functionalization of complex natural products.  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