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   917篇
  免费   76篇
  993篇
  2022年   6篇
  2021年   9篇
  2020年   3篇
  2019年   7篇
  2018年   12篇
  2017年   13篇
  2016年   22篇
  2015年   33篇
  2014年   41篇
  2013年   43篇
  2012年   53篇
  2011年   65篇
  2010年   39篇
  2009年   56篇
  2008年   44篇
  2007年   57篇
  2006年   45篇
  2005年   46篇
  2004年   51篇
  2003年   44篇
  2002年   54篇
  2001年   11篇
  2000年   10篇
  1999年   6篇
  1998年   14篇
  1997年   12篇
  1996年   8篇
  1995年   6篇
  1994年   8篇
  1993年   8篇
  1992年   4篇
  1991年   8篇
  1990年   3篇
  1989年   6篇
  1988年   5篇
  1987年   4篇
  1985年   3篇
  1982年   4篇
  1981年   4篇
  1980年   3篇
  1979年   4篇
  1969年   3篇
  1914年   3篇
  1908年   4篇
  1888年   10篇
  1887年   11篇
  1886年   16篇
  1885年   12篇
  1884年   8篇
  1858年   3篇
排序方式: 共有993条查询结果,搜索用时 15 毫秒
981.
Mährische Rosen     
Ohne Zusammenfassung  相似文献   
982.
Summary Several bacteria, yeast and fungi selectively isolated from paper-mill waste-water grew on veratryl alcohol, a key intermediate of lignin metabolism. Penicillium simplicissimum oxidized veratryl alcohol via a NAD(P)+-dependent veratryl alcohol dehydrogenase to veratraldehyde, which was further oxidized to veratric acid in a NAD(P)+-dependent reaction. Veratric-acid-grown cells contained NAD(P)H-dependent O-demethylase activity for veratrate, vanillate and isovanillate. Protocatechuate was cleaved by a protocatechuate 3,4-dioxygenase. Offprint requests to: E. de Jong  相似文献   
983.
984.
985.
For scientific, ethical and economic reasons, experiments involving animals should be appropriately designed, correctly analysed and transparently reported. This increases the scientific validity of the results, and maximises the knowledge gained from each experiment. A minimum amount of relevant information must be included in scientific publications to ensure that the methods and results of a study can be reviewed, analysed and repeated. Omitting essential information can raise scientific and ethical concerns. We report the findings of a systematic survey of reporting, experimental design and statistical analysis in published biomedical research using laboratory animals. Medline and EMBASE were searched for studies reporting research on live rats, mice and non-human primates carried out in UK and US publicly funded research establishments. Detailed information was collected from 271 publications, about the objective or hypothesis of the study, the number, sex, age and/or weight of animals used, and experimental and statistical methods. Only 59% of the studies stated the hypothesis or objective of the study and the number and characteristics of the animals used. Appropriate and efficient experimental design is a critical component of high-quality science. Most of the papers surveyed did not use randomisation (87%) or blinding (86%), to reduce bias in animal selection and outcome assessment. Only 70% of the publications that used statistical methods described their methods and presented the results with a measure of error or variability. This survey has identified a number of issues that need to be addressed in order to improve experimental design and reporting in publications describing research using animals. Scientific publication is a powerful and important source of information; the authors of scientific publications therefore have a responsibility to describe their methods and results comprehensively, accurately and transparently, and peer reviewers and journal editors share the responsibility to ensure that published studies fulfil these criteria.  相似文献   
986.
987.
The ZAP-70 tyrosine kinase is essential for T cell activation by the T cell receptor. We show that ZAP-70 is also required for migration of T cells that is dependent on the integrin LFA-1. Invasion of TAM2D2 T cell hybridoma cells into fibroblast monolayers, which is LFA-1–dependent, was blocked by overexpression of dominant-negative ZAP-70 and by piceatannol but not by herbimycin A. The Syk inhibitor piceatannol blocks the Syk homologue ZAP-70, which is expressed by TAM2D2 cells, with the same dose dependence as the inhibition of invasion. Dominant-negative ZAP-70 completely inhibited the extensive metastasis formation of TAM2D2 cells to multiple organs upon i.v. injection into mice. Migration of TAM2D2 cells through filters coated with the LFA-1 ligand ICAM-1, induced by 1 ng/ml of the chemokine SDF-1, was blocked by anti–LFA-1 mAb and also abrogated by dominant-negative ZAP-70 and piceatannol. In contrast, migration induced by 100 ng/ml SDF-1 was independent of both LFA-1 and ZAP-70. LFA-1 cross-linking induced tyrosine phosphorylation, which was blocked by dominant-negative ZAP-70 and piceatannol. We conclude that LFA-1 engagement triggers ZAP-70 activity that is essential for LFA-1–dependent migration.  相似文献   
988.
989.
990.
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