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   6312篇
  免费   409篇
  国内免费   445篇
  2024年   9篇
  2023年   58篇
  2022年   160篇
  2021年   324篇
  2020年   193篇
  2019年   258篇
  2018年   233篇
  2017年   193篇
  2016年   260篇
  2015年   389篇
  2014年   456篇
  2013年   483篇
  2012年   553篇
  2011年   532篇
  2010年   352篇
  2009年   291篇
  2008年   342篇
  2007年   296篇
  2006年   268篇
  2005年   234篇
  2004年   205篇
  2003年   153篇
  2002年   133篇
  2001年   99篇
  2000年   82篇
  1999年   85篇
  1998年   46篇
  1997年   60篇
  1996年   60篇
  1995年   47篇
  1994年   36篇
  1993年   38篇
  1992年   50篇
  1991年   43篇
  1990年   28篇
  1989年   21篇
  1988年   12篇
  1987年   26篇
  1986年   16篇
  1985年   16篇
  1984年   1篇
  1983年   6篇
  1982年   5篇
  1981年   3篇
  1980年   4篇
  1977年   2篇
  1974年   1篇
  1973年   2篇
  1968年   1篇
  1967年   1篇
排序方式: 共有7166条查询结果,搜索用时 0 毫秒
991.
992.
993.
Wu Dai  Chris H. Dietrich 《ZooKeys》2012,(239):95-102
Tardrabassus pakneunensis, n. gen. & sp. is described and illustrated. The new genus shows morphological affinities to three leafhopper subfamilies, Tartessinae, Deltocephalinae, and Iassinae, but is tentatively placed in Iassinae based on the position of the ocelli, the reduced lateral frontal sutures, the leg chaetotaxy, and the structure of the male genitalia.  相似文献   
994.
Cell growth needs to be monitored in biological studies and bioprocess optimization. In special circumstances, such as microbial fermentations in media containing insoluble particles, accurate cell growth quantification is a challenge with current methods. Only the Burton method is applicable in such circumstances. The original Burton method was previously simplified by adopting a two-step sample pretreatment in perchloric acid procedure to eliminate the need for DNA extraction. Here, we further simplified the Burton method by replacing the previous two-step perchloric acid pretreatment with a new and one-step diphenylamine reagent pretreatment. The reliability and accuracy of this simplified method were assessed by measuring the biomass of four model microorganisms: Escherichia coli, Streptomyces clavuligerus, Saccharomyces cerevisiae, and Trichoderma reesei grown in normal media or those containing solid particles. The results demonstrate that this new simplified method performs comparably to the conventional methods, such as OD600 or the previously modified Burton method, and is much more sensitive than the dry weight method. Overall, the new method is simple, reliable, easy to perform, and generally applicable in most circumstances, and it reduces the operation time from more than 12 h (for the previously simplified Burton method) to about 2 h.  相似文献   
995.
996.
997.
998.
Hypersensitive C-reaction protein (hsCRP) may be a risk factor for cognitive impairment resulting from Alzheimer’s disease (AD), stroke, and vascular dementia. This study explored the correlation of peripheral blood hsCRP level with cognitive decline due to high altitude exposure. The study was conducted on 100 male military participants who had never been to high altitude. Cerebral oxygen saturation monitoring, event related potentials (P300, N200) detection, and neurocognitive assessment was performed and total hsCRP, interleukin-6 (IL-6), and homocysteine was estimated at 500m altitude, 3650m altitude, 3day, 1, and 3 month post arriving at the base camp (4400m), and 1 month after coming back to the 500m altitude. High altitude increased brain oxygen saturation, prolonged P300 and N200 latencies, injured cognitive functions, and raised plasma hsCRP levels. But they all recovered in varying degrees at 1 and 3 month post arriving at the base camp (4400m). P300 latencies and hsCRP levels were strongly correlated to cognitive performances. These results suggested that cognitive deterioration occurred during the acute period of exposure to high altitude and may recover probably owning to acclimatization after extended stay at high altitude. Plasma hsCRP is inversely correlated to neurological cognition and it may be a potential biomarker for the prediction of high altitude induced cognitive dysfunction.  相似文献   
999.
Bioprocess and Biosystems Engineering - Ionic liquids (ILs) as “green” solvents have been widely used owing to their excellent properties, e.g., for biodiesel production. Crude glycerol...  相似文献   
1000.
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