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   1028773篇
  免费   107371篇
  国内免费   410篇
  2018年   9744篇
  2017年   9243篇
  2016年   13199篇
  2015年   17121篇
  2014年   20320篇
  2013年   29270篇
  2012年   32879篇
  2011年   33587篇
  2010年   22925篇
  2009年   21163篇
  2008年   30010篇
  2007年   31303篇
  2006年   29260篇
  2005年   28111篇
  2004年   27633篇
  2003年   26766篇
  2002年   26245篇
  2001年   45874篇
  2000年   45688篇
  1999年   36457篇
  1998年   13106篇
  1997年   13301篇
  1996年   12715篇
  1995年   11744篇
  1994年   11438篇
  1993年   11331篇
  1992年   30037篇
  1991年   29374篇
  1990年   28595篇
  1989年   27755篇
  1988年   25611篇
  1987年   24323篇
  1986年   22674篇
  1985年   22526篇
  1984年   18577篇
  1983年   16171篇
  1982年   12270篇
  1981年   11091篇
  1980年   10302篇
  1979年   17506篇
  1978年   13658篇
  1977年   12316篇
  1976年   11652篇
  1975年   13108篇
  1974年   13974篇
  1973年   13742篇
  1972年   12616篇
  1971年   11132篇
  1970年   9819篇
  1969年   9576篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Enterotoxigenic reference strains of Staphylococcus aureus were cultivated in sterile whole and skim milk for 18 h at 37°G. Staphylococcal enterotoxin A, B, and C were detected directly in the milk by an enzyme linked immunosorbent assay (ELISA), sensitive down to 1 ng/ml. Enterotoxins in the range of 1 ng–20 µg/ml milk were detected without any concentration or extraction. Skim and whole milk were almost identical as medium for enterotoxin production.  相似文献   
992.
A protein isolated from maize scutella which inhibits catalase in vitro has been shown to contain 12% carbohydrate in the form of galactose. This corresponds to four galactose molecules per inhibitor subunit. Removal of the carbohydrate with β-galactosidase or blockage with a galactose-specific lectin abolished activity of the inhibitor.  相似文献   
993.
994.
995.
996.
997.
Two distinct rat propagates of a radiation leukemia virus (RadLV-Rs) from the C57BL mouse respectively induced characteristic leukemogenic effects. These were found to be related with the infection titers of the isolates, but not with either their antigenic specificities or their viral and proviral genome sequences.  相似文献   
998.
999.
By means of the histostereometrical method, peculiarities of the thyroid gland formation have been studied in the lemming (Dicrostonyx torquatus) fetuses and newborns at the stage of the population quantity drop, as well specificity of the organ's morphofunctional state during the postnatal period. On the 14th prenatal day the thyroid gland already has the follicular structure. Up to the 19th day progressive follicular growth, accumulation of colloid and increase of its density occur. On the 19th-20th days, as well as in newborn animals, there are certain signs, demonstrating as essential activation of the thyroid gland function. In the newborn animals cavities of the completely formed follicles are devastated. During the postnatal period again growth of follicles, accumulation of colloid are observed, signs of hypersecretion of the hypophysis appear.  相似文献   
1000.
Human long-latency auditory evoked potentials were studied during simulation with variable-amplitude pulse sequences from a sound source moving to and from the subject. The N1 peak parameters were shown to depend on an accurate estimate of the direction of the change in the distance to the sound source. Differences in the processing of signals that simulated the approaching and/or distancing of the sound source were found in the N1 and P2 component parameters of on- and off-responses as was a more pronounced long negative potential shift in the evoked response to the approaching source as compared to the distancing source.  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