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   22130篇
  免费   1787篇
  国内免费   812篇
  2024年   25篇
  2023年   212篇
  2022年   248篇
  2021年   1022篇
  2020年   608篇
  2019年   766篇
  2018年   767篇
  2017年   568篇
  2016年   905篇
  2015年   1362篇
  2014年   1481篇
  2013年   1609篇
  2012年   2056篇
  2011年   1834篇
  2010年   1121篇
  2009年   1018篇
  2008年   1227篇
  2007年   1109篇
  2006年   966篇
  2005年   806篇
  2004年   746篇
  2003年   632篇
  2002年   567篇
  2001年   360篇
  2000年   284篇
  1999年   268篇
  1998年   208篇
  1997年   176篇
  1996年   172篇
  1995年   137篇
  1994年   134篇
  1993年   108篇
  1992年   157篇
  1991年   121篇
  1990年   92篇
  1989年   99篇
  1988年   75篇
  1987年   80篇
  1986年   74篇
  1985年   62篇
  1984年   63篇
  1983年   65篇
  1982年   32篇
  1981年   29篇
  1980年   29篇
  1979年   30篇
  1978年   21篇
  1977年   24篇
  1976年   20篇
  1975年   18篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Human RSV is one of the most prevalent viral pathogens of early childhood for which no vaccine is available. Herein we provide an analysis of RSV epitope data to examine its application to vaccine design and development. Our objective was to provide an overview of antigenic coverage, identify critical antibody and T cell determinants, and then analyze the cumulative RSV epitope data from the standpoint of functional responses using a combinational approach to characterize antigenic structure and epitope location. A review of the cumulative data revealed, not surprisingly, that the vast majority of epitopes have been defined for the two major surface antigens, F and G. Antibody and T cell determinants have been reported from multiple hosts, including those from human subjects following natural infection, however human data represent a minority of the data. A structural analysis of the major surface antigen, F, showed that the majority of epitopes defined for functional antibodies (neutralizing and/or protective) were either shown to bind pre-F or to be accessible in both pre- and post-F forms. This finding may have has implications for on-going vaccine design and development. These interpretations are in agreement with previous work and can be applied in the larger context of functional epitopes on the F protein. It is our hope that this work will provide the basis for further RSV-specific epitope discovery and investigation into the nature of antigen conformation in immunogenicity.  相似文献   
22.
Bacillus sp. strain FJAT-13831 was isolated from the no. 1 pit soil of Emperor Qin''s Terracotta Warriors in Xi''an City, People''s Republic of China. The isolate showed a close relationship to the Bacillus cereus group. The draft genome sequence of Bacillus sp. FJAT-13831 was 4,425,198 bp in size and consisted of 5,567 genes (protein-coding sequences [CDS]) with an average length of 782 bp and a G+C value of 36.36%.  相似文献   
23.
24.
25.
26.
27.
28.
The biosynthesis of glyantrypine from radiolabelled amino acid precursors has been shown experimentally to involve anthranilic acid, tryptophan and glycine. Low values for percentage incorporation of radiolabel into glyantrypine were partly influenced by a complex array of other novel alkaloids shown by the radiolabelling experiments to be related to glyantrypine. Interpretation of radiolabel incorporation from [14C-carboxyl]-anthranilic acid into microbial metabolites seen to contain an anthranilyl moiety in various biosynthetic arrangements is discussed. The possibility of diversion of anthranilic acid from the kynurenine pathway to glyantrypine biosynthesis is recognised.  相似文献   
29.
Due to the direction, intensity, duration and consistency of genetic selection, especially recent artificial selection, the production performance of domestic pigs has been greatly changed. Therefore, we reasoned that there must be footprints or selection signatures that had been left during domestication. In this study, with porcine 60K BeadChip genotyping data from both commercial Large White and local Chinese Tongcheng pigs, we calculated the extended haplotype homozygosity values of the two breeds using the long‐range haplotype method to detect selection signatures. We found 34 candidate regions, including 61 known genes, from Large White pigs and 25 regions comprising 57 known genes from Tongcheng pigs. Many selection signatures were found on SSC1, SSC4, SSC7 and SSC14 regions in both populations. According to quantitative trait loci and network pathway analyses, most of the regions and genes were linked to growth, reproduction and immune responses. In addition, the average genetic differentiation coefficient FST was 0.254, which means that there had already been a significant differentiation between the breeds. The findings from this study can contribute to further research on molecular mechanisms of pig evolution and domestication and also provide valuable references for improvement of their breeding and cultivation.  相似文献   
30.
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