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   824篇
  免费   54篇
  2023年   4篇
  2021年   9篇
  2020年   6篇
  2019年   6篇
  2018年   10篇
  2017年   14篇
  2016年   15篇
  2015年   25篇
  2014年   24篇
  2013年   30篇
  2012年   44篇
  2011年   45篇
  2010年   19篇
  2009年   29篇
  2008年   53篇
  2007年   46篇
  2006年   28篇
  2005年   47篇
  2004年   47篇
  2003年   33篇
  2002年   33篇
  2001年   31篇
  2000年   25篇
  1999年   26篇
  1998年   10篇
  1997年   7篇
  1996年   7篇
  1995年   7篇
  1994年   4篇
  1993年   6篇
  1992年   23篇
  1991年   14篇
  1990年   17篇
  1989年   25篇
  1988年   10篇
  1987年   8篇
  1986年   7篇
  1985年   13篇
  1984年   8篇
  1983年   6篇
  1981年   5篇
  1978年   4篇
  1974年   4篇
  1973年   3篇
  1972年   5篇
  1971年   3篇
  1970年   4篇
  1969年   6篇
  1968年   4篇
  1967年   3篇
排序方式: 共有878条查询结果,搜索用时 31 毫秒
871.
Biological Trace Element Research - Selenomethionine is able to relieve the effect of inflammation in various tissues and organs. However, there are few studies about the influences of organic...  相似文献   
872.
Nozaki  H.  Matsuzaki  M.  Misumi  O.  & Kuroiwa  T. 《Journal of phycology》2003,39(S1):45-45
Travertine terraces have been deposited by calcareous hot springs in Yellowstone from as early as 365,000 years to the present. Most of these porous and non-porous CaCO3 rocks (old or new) contain a 1–2 mm thick greenish band about 1–3 mm below the upper surface. These bands are composed of cyanobacteria and, sometimes, unicellular green algae. Although some moisture may be retained for much of the year, all undergo freezing in winter and desiccation in summer. DGGE (denaturing gradient gel electrophoresis), with subsequent 16S rDNA sequence analyses of bands, has shown that relatively few phylotypes of cyanobacteria are present, but some occur in travertine of very different ages, indicating secondary establishment of the communities. Clonal cultures of predominant types have also been established and sequenced. All those tested are able to survive extreme desiccation. Preliminary sequence analyses of cultures show that some strains are nearly identical to known cyanobacterial strains while others show little similarity. One sequence is 100% identical to the cyanobacterium Cyanobium gracile. This cyanobacterium is known to be distributed worldwide in lakes and brackish seas, but not in a cryptoendolithic environment. Another sequence shows 99% identity to two cyanobacteria isolated from Antarctic freshwater ponds. Both Antarctic ponds and Yellowstone travertine are environments in which adaptations for desiccation and/or freezing tolerance could be crucial. The lack of ecological similarity among some of these strains indicates that genes other than 16S rDNA must be used for differentiation. These results will be discussed along with the ecology of travertine habitats.  相似文献   
873.
Protein kinase C delta (PKC delta) is activated through tyrosine phosphorylation and is involved in apoptosis induction in the H(2)O(2)-treated fibroblasts. In the human keratinocyte HaCaT cell line, ultraviolet radiation, which induces apoptosis, promoted tyrosine phosphorylation and activation of PKC delta, but neither enhanced threonine phosphorylation in the activation loop nor generated the catalytic fragment of the PKC isoform. Tyrosine phosphorylation of PKC delta was prevented by a radical scavenger, N-acetyl-l-cysteine, and by a tyrosine kinase inhibitor, genistein, in the ultraviolet-irradiated keratinocyte cell line. Ultraviolet radiation-induced apoptosis was attenuated by N-acetyl-l-cysteine and genistein as well as by a PKC inhibitor, bisindolylmaleimide I. These results indicate that reactive oxygen species generated by ultraviolet radiation enhance tyrosine phosphorylation of PKC delta, and the PKC isoform thus activated by the modification reaction contributes to induction of apoptotic cell death in keratinocytes.  相似文献   
874.
875.
1. Trachea cartilages were dissected from normal and dwarf chickens which had been injected with thyroxine (T4, 200 micrograms/kg) or triiodothyronine (T3, 200 micrograms/kg) for seven consecutive days, and were analysed for nucleic acids, proteins and polyamines. 2. In saline-injected control chickens, RNA, but not DNA and protein, concentration of the cartilage was higher in dwarfs than in normals. The concentration of putrescine was lower in dwarfs than in normals, while that of spermine was the reverse. 3. Thyroid hormones, especially T3, tended to increase concentrations of RNA, spermidine and spermine, and to decrease that of putrescine. However, there were no clear differences in the response to hormones between breeds.  相似文献   
876.
877.
Journal of Plant Research - The model plant Arabidopsis thaliana has five double-stranded RNA-binding proteins (DRB1-DRB5), two of which, DRB1 and DRB4, are well characterized. In contrast, the...  相似文献   
878.
Genetic manipulation techniques for marine protists are not well-established, despite immense efforts. However, Perkinsus marinus is an exception and can be developed as a genetically tractable model organism for related protists. Here, we designed a new plasmid for Pmarinus that allows two proteins from a single mRNA to be differently localized using a self-cleaving 2A peptide. This enabled us to establish a stable transfectant expressing a mitochondrially targeted fluorescent protein. The system can be applied to any protein in theory and would make a powerful tool for investigating unique organelles in Pmarinus and related dinoflagellates.  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