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   1481561篇
  免费   137852篇
  国内免费   1466篇
  1620879篇
  2021年   17976篇
  2019年   16207篇
  2018年   18235篇
  2017年   17006篇
  2016年   28418篇
  2015年   42746篇
  2014年   50802篇
  2013年   77022篇
  2012年   39731篇
  2011年   28887篇
  2010年   44720篇
  2009年   45752篇
  2008年   27088篇
  2007年   25472篇
  2006年   30193篇
  2005年   31353篇
  2004年   30494篇
  2003年   28096篇
  2002年   26323篇
  2001年   44079篇
  2000年   41817篇
  1999年   39026篇
  1998年   26540篇
  1997年   26360篇
  1996年   25754篇
  1995年   23869篇
  1994年   23684篇
  1993年   22839篇
  1992年   33535篇
  1991年   31748篇
  1990年   30148篇
  1989年   30773篇
  1988年   28428篇
  1987年   26786篇
  1986年   25088篇
  1985年   26867篇
  1984年   25653篇
  1983年   22684篇
  1982年   22088篇
  1981年   21059篇
  1980年   19683篇
  1979年   21987篇
  1978年   19794篇
  1977年   18889篇
  1976年   17776篇
  1975年   17585篇
  1974年   18212篇
  1973年   18606篇
  1972年   15896篇
  1971年   14658篇
排序方式: 共有10000条查询结果,搜索用时 7 毫秒
111.
112.
Zooplankton data collected during September 1995 in the NorthWest Atlantic at 4139'N, 4958'W (the location of the siteof the ‘Titanic’ wreck) were analysed. The regioninvestigated was characterized by a very sharp frontal zonebetween the Gulf Stream and the main stream of the LabradorCurrent. The total plankton biomass in the water column wasvery high. The macroplankton biomass values below the 600 mlayer were significantly higher as compared with the similarvalues measured before in other productive boreal regions ofthe Atlantic and Pacific oceans. A lot of dead mesoplanktonanimals occurred in the deep layers. The reason was that thecold-water mesoplankton advected by the Labrador Current diedoff intensively within the deep layers of the frontal zone andwere used as a food resource by the macroplankton carnivoresand scavengers that were very abundant there.  相似文献   
113.
114.
Argon laser surgery is an effective treatment for ectasias and congenital port-wine stains; however, its use in children under the age of 13 is controversial. This paper reviews 202 children under the age of 13 who underwent argon laser treatments for congenital port-wine stains, spider angiomas, epidermal nevi, and lentigines. The clinical characteristics of port-wine stains in 170 children are discussed. Good to excellent results (moderate to complete clearing) in port-wine stains were obtained in 60 percent of patients and seemed to correlate best with lack of blanchability on pressure. Hypertrophic scarring was seen in only 7 children, all of whom had undressed wounds; no significant scarring has been seen in any subsequent child who had maintained a dressed wound postoperatively.  相似文献   
115.
116.
Trigger finger is a relatively common clinical entity, most frequently caused by stenosing tenosynovitis. Several other conditions not related to tenosynovitis also have been described as a cause of triggering, and these have been reviewed. We present a rare anomaly of the fourth lumbrical muscle insertion as a cause of triggering of the right little finger. This was completely relieved following excision of the anomalous muscle. This rare anatomic variant should be added to the list of potential causes of trigger finger.  相似文献   
117.
118.
119.
120.
Besides vobtusine and vobtusine-lactone, deoxyvobtusine was isolated from the leaves of Voacanga grandifolia (Miq. Rolfe. Spectral and chemical evi  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