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   709071篇
  免费   76020篇
  国内免费   570篇
  2018年   6947篇
  2017年   6774篇
  2016年   9250篇
  2015年   11437篇
  2014年   13782篇
  2013年   19981篇
  2012年   22074篇
  2011年   22930篇
  2010年   15531篇
  2009年   14155篇
  2008年   20105篇
  2007年   20700篇
  2006年   19491篇
  2005年   18689篇
  2004年   18386篇
  2003年   17664篇
  2002年   17091篇
  2001年   36010篇
  2000年   35849篇
  1999年   27844篇
  1998年   8680篇
  1997年   9258篇
  1996年   8691篇
  1995年   8048篇
  1994年   7717篇
  1993年   7646篇
  1992年   21960篇
  1991年   21090篇
  1990年   20580篇
  1989年   20038篇
  1988年   18410篇
  1987年   17240篇
  1986年   15925篇
  1985年   15971篇
  1984年   12991篇
  1983年   11010篇
  1982年   8038篇
  1981年   7316篇
  1980年   6865篇
  1979年   12038篇
  1978年   9243篇
  1977年   8519篇
  1976年   7880篇
  1975年   8785篇
  1974年   9466篇
  1973年   9339篇
  1972年   8403篇
  1971年   7685篇
  1970年   6732篇
  1969年   6261篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
211.
For decades, the bio-duck sound has been recorded in the Southern Ocean, but the animal producing it has remained a mystery. Heard mainly during austral winter in the Southern Ocean, this ubiquitous sound has been recorded in Antarctic waters and contemporaneously off the Australian west coast. Here, we present conclusive evidence that the bio-duck sound is produced by Antarctic minke whales (Balaenoptera bonaerensis). We analysed data from multi-sensor acoustic recording tags that included intense bio-duck sounds as well as singular downsweeps that have previously been attributed to this species. This finding allows the interpretation of a wealth of long-term acoustic recordings for this previously acoustically concealed species, which will improve our understanding of the distribution, abundance and behaviour of Antarctic minke whales. This is critical information for a species that inhabits a difficult to access sea-ice environment that is changing rapidly in some regions and has been the subject of contentious lethal sampling efforts and ongoing international legal action.  相似文献   
212.
Georg Söderbom 《Ethnos》2013,78(1-2):95-100
Current debates over the concept of culture are examined, especially with regard to the relationship of culture to bounded collectivities, human nature, and individuality; present‐day views are seen against the background of back‐and‐forth swings in the history of anthropological thought. Recent theorizing about cultural acquisition is also considered.  相似文献   
213.
Selective diapedesis of Th1 cells induced by endothelial cell RANTES.   总被引:16,自引:0,他引:16  
Differentiated CD4 T cells can be divided into Th1 and Th2 types based on the cytokines they produce. Differential expression of chemokine receptors on either the Th1-type or the Th2-type cell suggests that Th1-type and Th2-type cells differ not only in cytokine production but also in their migratory capacity. Stimulation of endothelial cells with IFN-gamma selectively enhanced transmigration of Th1-type cells, but not Th2-type cells, in a transendothelial migration assay. Enhanced transmigration of Th1-type cells was dependent on the chemokine RANTES produced by endothelial cells, as indicated by the findings that Ab neutralizing RANTES, or Ab to its receptor CCR5, inhibited transmigration. Neutralizing Ab to chemokines macrophage-inflammatory protein-1alpha or monocyte chemotactic protein-1 did not inhibit Th1 selective migration. Whereas anti-CD18 and anti-CD54 blocked basal levels of Th1-type cell adherence to endothelial cells and also inhibited transmigration, anti-RANTES blocked only transmigration, indicating that RANTES appeared to induce transmigration of adherent T cells. RANTES seemed to promote diapedesis of adherent Th1-type cells by augmenting pseudopod formation in conjunction with actin rearrangement by a pathway that was sensitive to the phosphoinositol 3-kinase inhibitor wortmannin and to the Rho GTP-binding protein inhibitor, epidermal cell differentiation inhibitor. Thus, enhancement of Th1-type selective migration appeared to be responsible for the diapedesis induced by interaction between CCR5 on Th1-type cells and RANTES produced by endothelial cells. Further evidence that CCR5 and RANTES play a modulatory role in Th1-type selective migration derives from the abrogation of this migration by anti-RANTES and anti-CCR5 Abs.  相似文献   
214.
215.
216.
217.
218.
219.
220.
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