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   960079篇
  免费   92871篇
  国内免费   331篇
  2018年   9511篇
  2017年   9248篇
  2016年   13978篇
  2015年   19738篇
  2014年   22330篇
  2013年   29922篇
  2012年   32503篇
  2011年   31131篇
  2010年   21865篇
  2009年   20299篇
  2008年   26859篇
  2007年   27945篇
  2006年   26213篇
  2005年   30435篇
  2004年   29096篇
  2003年   26715篇
  2002年   24186篇
  2001年   39632篇
  2000年   38994篇
  1999年   31710篇
  1998年   11607篇
  1997年   11645篇
  1996年   10994篇
  1995年   10214篇
  1994年   9833篇
  1993年   9937篇
  1992年   26283篇
  1991年   25931篇
  1990年   25250篇
  1989年   24677篇
  1988年   22769篇
  1987年   21878篇
  1986年   20342篇
  1985年   20305篇
  1984年   16605篇
  1983年   14341篇
  1982年   10759篇
  1981年   9719篇
  1980年   9085篇
  1979年   15570篇
  1978年   12326篇
  1977年   11046篇
  1976年   10464篇
  1975年   11939篇
  1974年   12899篇
  1973年   12764篇
  1972年   11776篇
  1971年   10598篇
  1970年   9289篇
  1969年   9152篇
排序方式: 共有10000条查询结果,搜索用时 453 毫秒
961.
962.
963.
964.
965.
966.
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   
967.
968.
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   
969.
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   
970.
A comparison has been performed of catalytic properties of unicellular microorganism amine oxidases (AO) from two new enzyme sources, the bacteriumMethanosarcina barkeri and the infusoriaTetrahymena pyriformis. It was shown that the both studied AO deaminate tyramine, serotonin, and benzylamine, but do not deaminate histamine. The AO fromMethanosarcina barkeri catalyzes deamination of all three substrates at an identical rate, while the rate of tyramine deamination under effect of AO fromTetrahymena pyriformis is one order higher than the rate of serotonin deamination, and about two orders higher than the rate of benzylamine deamination. Based on the data of the substrate-inhibitor analysis, a suggestion was made about the existence of one center for the substrate binding in the AO of the studied bacterium, while several centers in the AO of the studied infusoria.  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