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   1398732篇
  免费   124513篇
  国内免费   1951篇
  2021年   18158篇
  2019年   16351篇
  2018年   18240篇
  2017年   16984篇
  2016年   28554篇
  2015年   42999篇
  2014年   51109篇
  2013年   77499篇
  2012年   40108篇
  2011年   29403篇
  2010年   44739篇
  2009年   45824篇
  2008年   27251篇
  2007年   25319篇
  2006年   30123篇
  2005年   31018篇
  2004年   30261篇
  2003年   27537篇
  2002年   25506篇
  2001年   35169篇
  2000年   32490篇
  1999年   32302篇
  1998年   25661篇
  1997年   25559篇
  1996年   25005篇
  1995年   23186篇
  1994年   22923篇
  1993年   22035篇
  1992年   28221篇
  1991年   26773篇
  1990年   25469篇
  1989年   26107篇
  1988年   23964篇
  1987年   22614篇
  1986年   21697篇
  1985年   23416篇
  1984年   23059篇
  1983年   20405篇
  1982年   20630篇
  1981年   19814篇
  1980年   18542篇
  1979年   19074篇
  1978年   18090篇
  1977年   17197篇
  1976年   16347篇
  1975年   16167篇
  1974年   16716篇
  1973年   17010篇
  1972年   14446篇
  1971年   13333篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
Indomethacin and substance BW-755C in experiments on isolated myometrium striae of pregnant white rats exert an inhibiting effect on the contractile uterus function due to inhibition of cyclooxygenase or lipoxygenase ways of the arachidonic acid transformation. Prostaglandin F2 alpha is sensitive to functioning of the cyclooxygenase and lipoxygenase ways of the arachidonic acid transformation, while oxytocin--only lipoxygenase one. Conclusions rest on results from multiparametric analysis of the contractile uterus function suggested by authors and confirmed by the pattern recognition method--the Karunen-Loev orthogonal decomposition.  相似文献   
962.
There was a range of severity of parasitism of stem-borer larvae by Hymenoptera and Nematoda and much premature death of the larvae. A nematode, Panagrolaimus rigidus, normally considered to be saprophytic, was implicated in some mortality of stem-borer larvae.  相似文献   
963.
964.
965.
We here report the second record of a developmentally aberrant strain of a cellular slime mold from natural populations and demonstrate that this Dictyostelium mucoroides variant is capable of undergoing normal morphogenesis in the presence of the phycomycete fungus, Mucor hiemalis. The synergism is induced by an extracellular product(s) which is diffusable through thin agar membranes and is released by the fungus. The presence of the fungus not only induces stalk formation in this stalkless variant, but also increases the rate of sorocarp formation in 3 of 5 additional species of cellular slime molds assayed.  相似文献   
966.
967.
Summary On adapting brackish waterAnguilla anguilla to fresh water it was noted that, while the plasma sodium, magnesium,pCO2 and pH were held reasonably constant, there was a substantial fall in chloride concentration (–33 mEq). The gradient of the linear correlations between plasma sodium and chloride also fell (brackish water gradient=0.92, fresh water gradient=0.21) indicating that a new pattern of plasma ion interrelationships was being established. Comparison with plasma Na/Cl ion ratios from other fishes suggested that this phenomenon was peculiar toA. anguilla. Corresponding with the very low plasma chloride levels plasma bicarbonate was four to five times that found in other fishes, and this was thought related to the finding that the haematocrit value almost doubled during adaptation to fresh water. In fresh water adapted fish a fall in plasma chloride was associated with a rise in plasma bicarbonate, however the charge compensation effect of this response was only partial as summing the common plasma cations and anions left an anion deficit of about 34 mEq to be accounted for.  相似文献   
968.
969.
970.
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