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   4406篇
  免费   232篇
  国内免费   126篇
  2024年   6篇
  2023年   70篇
  2022年   78篇
  2021年   121篇
  2020年   95篇
  2019年   84篇
  2018年   157篇
  2017年   132篇
  2016年   176篇
  2015年   125篇
  2014年   191篇
  2013年   319篇
  2012年   345篇
  2011年   383篇
  2010年   245篇
  2009年   156篇
  2008年   224篇
  2007年   218篇
  2006年   210篇
  2005年   213篇
  2004年   207篇
  2003年   230篇
  2002年   155篇
  2001年   99篇
  2000年   125篇
  1999年   77篇
  1998年   24篇
  1997年   23篇
  1996年   17篇
  1995年   9篇
  1994年   11篇
  1993年   14篇
  1992年   9篇
  1991年   11篇
  1990年   10篇
  1988年   14篇
  1987年   8篇
  1985年   8篇
  1984年   15篇
  1983年   10篇
  1982年   9篇
  1980年   10篇
  1979年   6篇
  1976年   6篇
  1975年   10篇
  1974年   6篇
  1973年   9篇
  1972年   7篇
  1971年   9篇
  1966年   6篇
排序方式: 共有4764条查询结果,搜索用时 15 毫秒
1.
Synchrony of Long Duration in Suspension Cultures of Mammalian Cells   总被引:1,自引:0,他引:1  
THE high-sulphur proteins of α-keratins, which constitute the non-filamentous matrix between the microfibrils, comprise several major groups of proteins, each group consisting of a number of closely related components. They are obtained in a soluble form by reduction of the disulphide bonds of wool and preferential extraction with alkaline thioglycollate at high ionic strength1. The thiol groups are subsequently stabilized by alkylation with iodoacetic acid.  相似文献   
2.
3.
Allopatric isolation in glacial refugia has caused differentiation and speciation in many taxa globally. In this study, we investigated the nuclear and mitochondrial genetic differentiation of the long fingered bat, Myotis capaccinii during the ice ages in south-eastern Europe and Anatolia. The mitochondrial DNA (mtDNA) analyses indicated a suture zone similar to those recorded in other animal species, including bats, suggesting the association of more than one refugium with the region. Contrary to most of the other species where a suture zone was seen in Anatolia, for M. capaccinii the geographical location of the genetic break was in south-eastern Europe. This mitochondrial differentiation was not reflected in the nuclear microsatellites, however, suggesting that the lack of contact during the ice ages did not result in reproductive isolation. Hence taxonomically, the two mitochondrial clades cannot be treated as separate species.  相似文献   
4.
1. Bergmann's rule states that organisms inhabiting colder environments show an increase in body size or mass in comparison to their conspecifics living in warmer climates. Although originally proposed for homoeothermic vertebrates, this rule was later extended to ectotherms. In social insects, only a few studies have tested this rule and the results were ambiguous. Here, ‘body size’ can be considered at two different levels (the size of the individual workers or the size of the colony). 2. In this study, data from 53 nests collected along altitudinal gradients in the Alps were used to test the hypotheses that the worker body size and colony size of the ant Leptothorax acervorum increase with increasing altitude and therefore follow Bergmann's rule. 3. The results show that the body size of workers but not the colony size increases with altitude. Whether this pattern is driven by starvation resistance or other mechanisms remains to be investigated.  相似文献   
5.
6.
7.
8.
9.
Cerebrohepatorenal malformation is a rare familial disorder characterized by typical renal lesions combined with Dandy-Walker malformation, and congenital hepatic fibrosis. In this case report, a male premie with the diagnosis of cerebrorenal syndrome or so called Goldston syndrome is presented. Besides the rarity of this syndrome, this case is the second reported patient diagnosed prenatally.  相似文献   
10.
Torture.     
  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