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   1713篇
  免费   130篇
  2022年   10篇
  2021年   8篇
  2020年   7篇
  2019年   7篇
  2018年   19篇
  2017年   18篇
  2016年   31篇
  2015年   44篇
  2014年   37篇
  2013年   73篇
  2012年   75篇
  2011年   64篇
  2010年   58篇
  2009年   45篇
  2008年   70篇
  2007年   77篇
  2006年   93篇
  2005年   62篇
  2004年   79篇
  2003年   64篇
  2002年   77篇
  2001年   81篇
  2000年   86篇
  1999年   60篇
  1998年   26篇
  1997年   33篇
  1996年   21篇
  1995年   17篇
  1994年   10篇
  1993年   20篇
  1992年   58篇
  1991年   43篇
  1990年   50篇
  1989年   34篇
  1988年   38篇
  1987年   38篇
  1986年   33篇
  1985年   19篇
  1984年   11篇
  1983年   12篇
  1982年   12篇
  1981年   8篇
  1980年   9篇
  1979年   14篇
  1977年   7篇
  1974年   7篇
  1973年   8篇
  1970年   7篇
  1969年   13篇
  1967年   9篇
排序方式: 共有1843条查询结果,搜索用时 15 毫秒
31.
Summary We have used the cDNA clone encoding maize glutathione-S-transferase (GST I) to isolate a genomic DNA clone containing the complete GST I gene. Nucleotide sequence analysis of the cDNA and genomic clones has yielded a complete amino acid sequence for maize GST I and provided the exon-intron map of its gene. The mRNA homologous sequences in the maize GST I gene consist of a 107 bp 5 untranslated region, a 642 bp coding region and 340 bp of the 3 untranslated region. They are divided into three exons by two introns which interrupt the coding region. The 5 untranslated spacer contains an unusual sequence of pentamer AGAGG repeated seven times. The inbred maize line (Missouri 17) contains a single gene for GST I, whereas the hybrid line (3780A) contains two genes. Nucleotide sequence analysis of the primer extended cDNA products reveals that the 5 untranslated regions of the two genes in the hybrid 3780A are identical except for a 6 bp internal deletion (or insertion). The amino acid sequence of maize GST I shares no apparent sequence homology with the published sequences of animal GST's and represents the first published sequence of a plant GST. re]19850813 ac]19851126  相似文献   
32.
Flavonoids in the leaves of twenty-eight species belonging to the Polygonaceae were studied. Thirty-three kinds of flavonoids were isolated, and eighteen kinds were obtained as crystals. Quercetin glycosides were commonly found in the family. In the quercetin glycosides, 3-O-rhamnoside was most frequently found: 3-O-glucuronide is also distributed widely. Myricetin glycosides were rare. Methylated flavonols were found in some species of the sectionsEchinocaulon andPersicaria. Eleven kinds ofC-glycosylflavones were found in the present survey, andC-glycosylflavones were distributed in all species of the genusRheum and in almost all species of the section Tiniaria.Rumex Acetosella andPolygonum suffultum are exceptional, the former contains flavone glycoside and the latterC-glycosylflavones only, as main components.  相似文献   
33.
It was demonstrated that thyrotropin-releasing hormone (TRH) elicited a paradoxical increase in basal GH levels in cancer patients. Out of 94 cancer patients, 50 were found to be GH responders and this phenomenon was more frequently recognized in female than in male cancer patients. In cancer patients under 59 years of age, the GH response to TRH was significantly greater in females than in males, although there was no sex difference in the GH response in patients above 60 years of age. In female cancer patients, the GH response to TRH was significantly greater in patients under 59 years of age than in patients above 60 years of age, while there was no age difference in the GH response in male cancer patients. It was concluded that paradoxical responses of serum GH to TRH were recognized in 53 per cent of cancer patients and were more frequently observed in female than in male cancer patients.  相似文献   
34.
35.
36.
37.
38.
39.
40.
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