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   121892篇
  免费   9624篇
  国内免费   9929篇
  2024年   174篇
  2023年   1390篇
  2022年   2756篇
  2021年   6117篇
  2020年   4225篇
  2019年   5253篇
  2018年   4973篇
  2017年   3677篇
  2016年   5168篇
  2015年   7485篇
  2014年   8852篇
  2013年   9377篇
  2012年   11233篇
  2011年   10170篇
  2010年   6348篇
  2009年   5682篇
  2008年   6560篇
  2007年   5882篇
  2006年   5127篇
  2005年   4083篇
  2004年   3428篇
  2003年   3182篇
  2002年   2668篇
  2001年   2152篇
  2000年   1989篇
  1999年   1961篇
  1998年   1202篇
  1997年   1155篇
  1996年   1112篇
  1995年   973篇
  1994年   920篇
  1993年   725篇
  1992年   969篇
  1991年   722篇
  1990年   563篇
  1989年   515篇
  1988年   401篇
  1987年   386篇
  1986年   297篇
  1985年   313篇
  1984年   173篇
  1983年   173篇
  1982年   115篇
  1981年   92篇
  1980年   64篇
  1979年   79篇
  1977年   59篇
  1975年   58篇
  1974年   52篇
  1973年   56篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
142.
143.
144.
145.
The CDKN1C gene encodes a cyclin‐dependent kinase inhibitor and is one of the key genes involved in the development of Beckwith–Wiedemann syndrome and cancer. In this study, using a direct sequencing approach based on a single nucleotide polymorphism (SNP) at genomic DNA and cDNA levels, we show that CDKN1C exhibits monoallelic expression in all seven studied organs (heart, liver, spleen, lung, kidney, muscle and subcutaneous fat) in cattle. To investigate how methylation regulates imprinting of CDKN1C in cattle, allele‐specific methylation patterns in two putative differential methylation regions (DMRs), the CDKN1C DMR and KvDMR1, were analyzed in three tissues (liver, spleen and lung) using bisulfite sequencing PCR. Our results show that in the CDKN1C DMR both parental alleles were unmethylated in all three analyzed tissues. In contrast, KvDMR1 was differentially methylated between the two parental alleles in the same tissues. Statistical analysis showed that there is a significant difference in the methylation level between the two parental alleles (< 0.01), confirming that this region is the DMR of KvDMR1 and that it may be correlated with CDKN1C imprinting.  相似文献   
146.
Rice eating and cooking quality (ECQ) is a major concern of breeders and consumers, determining market competitiveness worldwide. Rice grain protein content (GPC) is negatively related to ECQ, making it possible to improve ECQ by manipulating GPC. However, GPC is genetically complex and sensitive to environmental conditions; therefore, little progress has been made in traditional breeding for ECQ. Here, we report that CRISPR/Cas9-mediated knockout of genes encoding the grain storage protein glutelin rapidly produced lines with downregulated GPC and improved ECQ. Our finding provides a new strategy for improving rice ECQ.  相似文献   
147.
148.
Lin  Xiang  Lin  Shuang  Liu  Yuanlan  Zhao  Haiyan  Wang  Li  Hasi  Wuliji 《Plasmonics (Norwell, Mass.)》2018,13(5):1749-1758
Plasmonics - Large-scale ordered two-dimensional (2D) superlattices at oil/water interface were fabricated using single-crystal Au nanospheres (NSs) with different diameters as building blocks. A...  相似文献   
149.
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   
150.
This paper describes a generic algorithm for finding restrictionsites within DNA sequences. The ‘genericity’ ofthe algorithm is made possible through the use of set theory.Basic elements of DNA sequences, i.e. nucleotides (bases), arerepresented in sets, and DNA sequences, whether specific, ambiguousor even protein-coding, are represented as sequences of thosesets. The set intersection operation demonstrates its abilityto perform pattern-matching correctly on various DNA sequences.The performance analysis showed that the degree of complexityof the pattern matching is reduced from exponential to linear.An example is given to show the actual and potential restrictionsites, derived by the generic algorithm, in the DNA sequencetemplate coding for a synthetic calmodulin. Received on October 2, 1990; accepted on December 18, 1990  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