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   986篇
  免费   60篇
  2023年   5篇
  2022年   11篇
  2021年   34篇
  2020年   19篇
  2019年   20篇
  2018年   27篇
  2017年   30篇
  2016年   34篇
  2015年   51篇
  2014年   55篇
  2013年   83篇
  2012年   96篇
  2011年   83篇
  2010年   68篇
  2009年   50篇
  2008年   58篇
  2007年   45篇
  2006年   40篇
  2005年   34篇
  2004年   34篇
  2003年   24篇
  2002年   24篇
  2001年   7篇
  2000年   7篇
  1999年   9篇
  1998年   3篇
  1997年   4篇
  1996年   3篇
  1995年   3篇
  1994年   5篇
  1993年   6篇
  1992年   5篇
  1991年   11篇
  1990年   3篇
  1989年   5篇
  1988年   2篇
  1987年   5篇
  1986年   4篇
  1985年   5篇
  1984年   8篇
  1983年   3篇
  1982年   5篇
  1974年   1篇
  1973年   2篇
  1972年   1篇
  1971年   3篇
  1970年   3篇
  1969年   1篇
  1965年   3篇
  1950年   1篇
排序方式: 共有1046条查询结果,搜索用时 328 毫秒
81.
Five out of the nine benzene–toulene–ethylbenzene-xylene (BTEX) tolerant bacteria that demonstrated high protease activity on skim milk agar were isolated. Among them, isolate 115b identified as Bacillus pumilus exhibited the highest protease production. The protease produced was stable in 25% (v/v) benzene and toluene and it was activated 1.7 and 2.5- fold by n-dodecane and n-tetradecane, respectively. The gene encoding the organic solvent tolerant protease was cloned and its nucleotide sequence determined. Sequence analysis revealed an open reading frame (ORF) of 1,149 bp that encoded a polypeptide of 383 amino acid residues. The polypeptide composed of 29 residues of signal peptide, a propeptide of 79 residues and a mature protein of 275 amino acids with a calculated molecular mass of 27,846 Da. This is the only report available to date on organic solvent tolerant protease from B. pumilus.  相似文献   
82.

Background  

Thermophilic Bacillus strains of phylogenetic Bacillus rRNA group 5 were described as a new genus Geobacillus. Their geographical distribution included oilfields, hay compost, hydrothermal vent or soils. The members from the genus Geobacillus have a growth temperatures ranging from 35 to 78°C and contained iso-branched saturated fatty acids (iso-15:0, iso-16:0 and iso-17:0) as the major fatty acids. The members of Geobacillus have similarity in their 16S rRNA gene sequences (96.5–99.2%). Thermophiles harboring intrinsically stable enzymes are suitable for industrial applications. The quest for intrinsically thermostable lipases from thermophiles is a prominent task due to the laborious processes via genetic modification.  相似文献   
83.
84.
Freshly collected individuals of Orchestia gammarellus from the supralittoral zone of Ghar El Melh lagoon (Northern of Tunisia) were housed in spring in a controlled-environment cabinet. Locomotor activity rhythm of this species was recorded in spring, at a constant temperature of 18 ± 0.5 °C. In the first experiment, juveniles and adults specimens were kept under light-dark cycle in phase with the natural diel cycle. In the two other experiments (males/females and mixed/unmixed groups), individuals of O. gammarellus were maintained under constant darkness. According to double-plotted actograms, waveforms and periodogram analysis, results revealed different locomotor pattern. However, locomotor rhythm of juveniles was more stable than adults. Also, the locomotor activity rhythm of groups was more defined than that of the isolated individuals. Moreover, the activity of mixed groups as well as unmixed groups was more pronounced than the activity of the isolated individuals. Furthermore, results showed no significant difference between locomotor rhythm pattern of males and females of this species.  相似文献   
85.
86.
87.
88.
Sequence heterogeneity at the ends of mature microRNAs (miRNAs) is well documented, but its effects on miRNA function are largely unexplored. Here we studied the impact of miRNA 5′-heterogeneity, which affects the seed region critical for target recognition. Using the example of miR-142-3p, an emerging regulator of the hematopoietic lineage in vertebrates, we show that naturally coexpressed 5′-variants (5′-isomiRs) can recognize largely distinct sets of binding sites. Despite this, both miR-142-3p isomiRs regulate exclusive and shared targets involved in actin dynamics. Thus, 5′-heterogeneity can substantially broaden and enhance regulation of one pathway. Other 5′-isomiRs, in contrast, recognize largely overlapping sets of binding sites. This is exemplified by two herpesviral 5′-isomiRs that selectively mimic one of the miR-142-3p 5′-isomiRs. We hypothesize that other cellular and viral 5′-isomiRs can similarly be grouped into those with divergent or convergent target repertoires, based on 5′-sequence features. Taken together, our results provide a detailed characterization of target recognition by miR-142-3p and its 5′-isomiR-specific viral mimic. We furthermore demonstrate that miRNA 5′-end variation leads to differential targeting and can thus broaden the target range of miRNAs.  相似文献   
89.
90.
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