全文获取类型
收费全文 | 28674篇 |
免费 | 2594篇 |
国内免费 | 1043篇 |
出版年
2023年 | 182篇 |
2022年 | 479篇 |
2021年 | 849篇 |
2020年 | 587篇 |
2019年 | 687篇 |
2018年 | 779篇 |
2017年 | 596篇 |
2016年 | 961篇 |
2015年 | 1508篇 |
2014年 | 1653篇 |
2013年 | 1945篇 |
2012年 | 2237篇 |
2011年 | 2149篇 |
2010年 | 1397篇 |
2009年 | 1074篇 |
2008年 | 1476篇 |
2007年 | 1332篇 |
2006年 | 1260篇 |
2005年 | 1124篇 |
2004年 | 1012篇 |
2003年 | 942篇 |
2002年 | 867篇 |
2001年 | 719篇 |
2000年 | 671篇 |
1999年 | 583篇 |
1998年 | 301篇 |
1997年 | 284篇 |
1996年 | 263篇 |
1995年 | 226篇 |
1994年 | 214篇 |
1993年 | 169篇 |
1992年 | 335篇 |
1991年 | 318篇 |
1990年 | 280篇 |
1989年 | 277篇 |
1988年 | 236篇 |
1987年 | 219篇 |
1986年 | 189篇 |
1985年 | 205篇 |
1984年 | 155篇 |
1983年 | 118篇 |
1982年 | 115篇 |
1981年 | 109篇 |
1979年 | 134篇 |
1978年 | 110篇 |
1977年 | 92篇 |
1976年 | 78篇 |
1975年 | 106篇 |
1974年 | 103篇 |
1973年 | 102篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
42.
43.
44.
The detection of sequence variation with restriction fragment length polymorphisms is advancing our knowledge of plant genetics on several fronts. In the past year, there has been progress in genetic map construction, phylogeny studies, and the dissection of multigenic traits. In addition, new methods that are independent of restriction sites are being developed for polymorphism detection. 相似文献
45.
Corinna Richter Ron L. Dy Rebecca E. McKenzie Bridget N.J. Watson Corinda Taylor James T. Chang Matthew B. McNeil Raymond H.J. Staals Peter C. Fineran 《Nucleic acids research》2014,42(13):8516-8526
Clustered regularly interspaced short palindromic repeats (CRISPR), in combination with CRISPR associated (cas) genes, constitute CRISPR-Cas bacterial adaptive immune systems. To generate immunity, these systems acquire short sequences of nucleic acids from foreign invaders and incorporate these into their CRISPR arrays as spacers. This adaptation process is the least characterized step in CRISPR-Cas immunity. Here, we used Pectobacterium atrosepticum to investigate adaptation in Type I-F CRISPR-Cas systems. Pre-existing spacers that matched plasmids stimulated hyperactive primed acquisition and resulted in the incorporation of up to nine new spacers across all three native CRISPR arrays. Endogenous expression of the cas genes was sufficient, yet required, for priming. The new spacers inhibited conjugation and transformation, and interference was enhanced with increasing numbers of new spacers. We analyzed ∼350 new spacers acquired in priming events and identified a 5′-protospacer-GG-3′ protospacer adjacent motif. In contrast to priming in Type I-E systems, new spacers matched either plasmid strand and a biased distribution, including clustering near the primed protospacer, suggested a bi-directional translocation model for the Cas1:Cas2–3 adaptation machinery. Taken together these results indicate priming adaptation occurs in different CRISPR-Cas systems, that it can be highly active in wild-type strains and that the underlying mechanisms vary. 相似文献
46.
Shi Fenghua Tan Muxiu Mo Qiaocheng Chen Xiaoying Zhao Yimin Guo Xiaoyun Jiang Ni 《Journal of plant biochemistry and biotechnology.》2020,29(3):528-538
Journal of Plant Biochemistry and Biotechnology - The dried buds of Lonicera hypoglauca Miq. have antipyretic, antidotal and anti-inflammatory properties and as Flos lonicerae are widely used in... 相似文献
47.
48.
49.
50.