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   698篇
  免费   143篇
  2022年   7篇
  2021年   13篇
  2018年   11篇
  2017年   16篇
  2016年   14篇
  2015年   23篇
  2014年   16篇
  2013年   20篇
  2012年   24篇
  2011年   27篇
  2010年   17篇
  2009年   19篇
  2008年   22篇
  2007年   30篇
  2006年   29篇
  2005年   24篇
  2004年   20篇
  2003年   22篇
  2002年   19篇
  2001年   22篇
  2000年   25篇
  1999年   16篇
  1998年   14篇
  1997年   8篇
  1996年   12篇
  1995年   8篇
  1994年   10篇
  1993年   9篇
  1992年   22篇
  1991年   23篇
  1990年   13篇
  1989年   21篇
  1988年   19篇
  1987年   9篇
  1986年   23篇
  1985年   14篇
  1984年   14篇
  1983年   11篇
  1982年   15篇
  1981年   12篇
  1980年   11篇
  1979年   9篇
  1978年   10篇
  1977年   10篇
  1976年   12篇
  1972年   6篇
  1971年   6篇
  1970年   7篇
  1969年   6篇
  1968年   9篇
排序方式: 共有841条查询结果,搜索用时 15 毫秒
771.
772.
773.
774.
Bryde's-like whales are a complex of medium-sized baleen whales that occur in tropical waters of all three major ocean basins. Currently, a single species of Bryde's whale, Balaenoptera edeni Anderson, 1879, is recognized, with two subspecies, Eden's whale, B. edeni edeni and Bryde's whale, B. edeni brydei (Olsen, 1913), although some authors have recognized these as separate species. Recently, a new, evolutionarily divergent lineage of Bryde's-like whale was identified based on genetic data and was found to be restricted primarily to the northern Gulf of Mexico (GOMx). Here, we provide the first morphological examination of a complete skull from these whales and identify diagnostic characters that distinguish it from the other medium-sized baleen whale taxa. In addition, we have increased the number of genetic samples of these Bryde's-like whales in the GOMx from 23 to 36 individuals, all of which matched the GOMx lineage. A review of Bryde's-like whale records in the Caribbean and greater Atlantic supports an isolated distribution for this unique lineage, augmenting the genetic and morphological body of evidence supporting the existence of an undescribed species of Balaenoptera from the Gulf of Mexico.  相似文献   
775.
776.
Summary The inducible L-arabinose transport system was characterized in Salmonella typhimurium LT2. Only one L-arabinose transport system with a Km of 2x10-4 M was identified. The results suggested that araE may be the only gene which codes for L-arabinose transport activity under the conditions tested. An araE-lac fusion strain was used to study the induction of the araE gene. No araE expression was detected when the L-arabinose concentration was lower than 1 mM. The expression of araE reached a maximum in the presence of 50 mM L-arabinose, and was significantly reduced in the presence of D-glucose. Expression of the araBAD and araE genes was coordinately regulated. The concentration of L-arabinose that allowed maximum araBAD gene expression was 50-fold lower in an araE + strain compared to an araE strain.  相似文献   
777.
Protein products of the bithorax complex in Drosophila   总被引:49,自引:0,他引:49  
R A White  M Wilcox 《Cell》1984,39(1):163-171
A sequence from the Ubx 5' exon in the bithorax complex of Drosophila melanogaster was expressed as a fusion protein in bacteria. This protein was used to raise rabbit antisera and monoclonal antibodies. These antibodies detect antigens that, on protein blots and by immunofluorescence on whole mounts of imaginal discs, show the predicted segmental distribution of Ubx products. These products are predominantly, if not totally, localized in the cell nucleus. In the embryonic nervous system nuclei are labeled from the second thoracic segment to the eighth abdominal segment. There is no labeling in homozygous Df bxd100 embryos.  相似文献   
778.
In ‘Pro‐life arguments against infanticide and why they are not convincing’ Joona Räsänen argues that Christopher Kaczor's objections to Giubilini and Minerva's position on infanticide are not persuasive. We argue that Räsänen's criticism is largely misplaced, and that he has not engaged with Kaczor's strongest arguments against infanticide. We reply to each of Räsänen's criticisms, drawing on the full range of Kaczor's arguments, as well as adding some of our own.  相似文献   
779.
780.
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