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   17288篇
  免费   1553篇
  国内免费   7篇
  2023年   105篇
  2022年   163篇
  2021年   363篇
  2020年   205篇
  2019年   283篇
  2018年   343篇
  2017年   278篇
  2016年   483篇
  2015年   751篇
  2014年   788篇
  2013年   947篇
  2012年   1274篇
  2011年   1255篇
  2010年   769篇
  2009年   669篇
  2008年   1001篇
  2007年   971篇
  2006年   937篇
  2005年   870篇
  2004年   872篇
  2003年   814篇
  2002年   766篇
  2001年   175篇
  2000年   136篇
  1999年   198篇
  1998年   203篇
  1997年   150篇
  1996年   151篇
  1995年   128篇
  1994年   137篇
  1993年   130篇
  1992年   132篇
  1991年   113篇
  1990年   114篇
  1989年   86篇
  1988年   107篇
  1987年   101篇
  1986年   96篇
  1985年   99篇
  1984年   104篇
  1983年   106篇
  1982年   103篇
  1981年   103篇
  1980年   93篇
  1979年   71篇
  1978年   66篇
  1977年   63篇
  1976年   65篇
  1974年   62篇
  1973年   60篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
For decades, the bio-duck sound has been recorded in the Southern Ocean, but the animal producing it has remained a mystery. Heard mainly during austral winter in the Southern Ocean, this ubiquitous sound has been recorded in Antarctic waters and contemporaneously off the Australian west coast. Here, we present conclusive evidence that the bio-duck sound is produced by Antarctic minke whales (Balaenoptera bonaerensis). We analysed data from multi-sensor acoustic recording tags that included intense bio-duck sounds as well as singular downsweeps that have previously been attributed to this species. This finding allows the interpretation of a wealth of long-term acoustic recordings for this previously acoustically concealed species, which will improve our understanding of the distribution, abundance and behaviour of Antarctic minke whales. This is critical information for a species that inhabits a difficult to access sea-ice environment that is changing rapidly in some regions and has been the subject of contentious lethal sampling efforts and ongoing international legal action.  相似文献   
3.
Sullivantia species were found to produce quercetin 3-O-glycosides, several of which contain glucuronic acid, as well as pedalitin (6-hydroxy-7-O-methyl luteolin), pedalitin 6-O-glycosides, and small amounts of luteolin. Sullivantia has a unique combination of compounds that distinguishes it from other genera in the Saxifraginae for which flavonoid data are available. The nature of the flavonoid compounds is in accordance with a general trend within the Saxifragaceae of reduction and replacement of flavonols by flavones.  相似文献   
4.
5.
The control of subcellular mRNA localization and translation is often mediated by protein factors that are directly or indirectly associated with the cytoskeleton. We report the identification and characterization of a rice seed protein that possesses both RNA and microtubule binding activities. In vitro UV cross-linking assays indicated that this protein binds to all mRNA sequences tested, although there was evidence for preferential binding to RNAs that contained A-C nucleotide sequence motifs. The protein was purified to homogeneity using a two-step procedure, and amino acid sequencing identified it as the multifunctional protein (MFP), a peroxisomal enzyme known to possess a number of activities involved in the beta-oxidation of fatty acids. The recombinant version of this rice MFP binds to RNA in UV cross-linking and gel mobility shift experiments, co-sediments specifically with microtubules, and possesses at least two enzymatic activities involved in peroxisomal fatty acid beta-oxidation. Taken together these data suggest that MFP has an important role in mRNA physiology in the cytoplasm, perhaps in regulating the localization or translation of mRNAs through an interaction with microtubules, in addition to its peroxisomal function.  相似文献   
6.
7.
8.
9.
10.
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