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   251263篇
  免费   23373篇
  国内免费   245篇
  2018年   2712篇
  2017年   2648篇
  2016年   3529篇
  2015年   3820篇
  2014年   4767篇
  2013年   6787篇
  2012年   7505篇
  2011年   8197篇
  2010年   5598篇
  2009年   4952篇
  2008年   7160篇
  2007年   7323篇
  2006年   6969篇
  2005年   6616篇
  2004年   6550篇
  2003年   6382篇
  2002年   6216篇
  2001年   12194篇
  2000年   12150篇
  1999年   9299篇
  1998年   2778篇
  1997年   2838篇
  1996年   2789篇
  1995年   2566篇
  1994年   2507篇
  1993年   2396篇
  1992年   7310篇
  1991年   7143篇
  1990年   7239篇
  1989年   6968篇
  1988年   6486篇
  1987年   6140篇
  1986年   5478篇
  1985年   5775篇
  1984年   4571篇
  1983年   3957篇
  1982年   2755篇
  1981年   2589篇
  1980年   2390篇
  1979年   4198篇
  1978年   3230篇
  1977年   2959篇
  1976年   2896篇
  1975年   3329篇
  1974年   3582篇
  1973年   3612篇
  1972年   3132篇
  1971年   2914篇
  1970年   2570篇
  1969年   2357篇
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
81.
Comparative tissue ascorbic acid studies in fishes   总被引:1,自引:0,他引:1  
Comparative tissue ascorbic acid levels in four species of major carp viz., Labeo rohila, L. calbasu, Cirrhina tnrigala and Catla catla , were investigated. The ascorbic acid level was found to be the highest in the spleen in the four species studied (range 430–380 μg/g) followed by the anterior (adrenal) kidney, gonads, liver, renal kidney, brain and/or eye. Heart and blood had the lowest levels (range 26–18 μg/ml) amongst the tissues studied. Overall tissue ascorbic acid levels were the highest in L. rohita and the lowest in C. mrigala . Investigation on seasonal variations in blood and kidney ascorbic acid levels of Notopterus notopterus revealed peak levels in spring (February-April) and the lowest levels in the postspawning period (August-September).  相似文献   
82.
83.
84.
Irradiation conditions in which laboratory animals were kept in experimental laboratories of Chernobyl and Kiev after the accident at the Chernobyl A.P.S. are described. The data are presented on the spectral structural and activity of radionuclides in the diet as well as in the organs and tissues of the animals. The radiation loads have been estimated with regard to an external gamma component and the internal one contributed by the incorporated radionuclides. It has been shown that radiation doses received by the animals during their lifetime due to these contributions do not exceed units of cGy.  相似文献   
85.
86.
87.
Identification of serotonin and dopamine in M. salmonis was conducted by means of some fluorometric methods. The presence of negligible amount of a serotonin-like component and substance close in its spectral characteristics to dopamine was shown.  相似文献   
88.
The effects of corticotropin-releasing hormone (CRH) injected into the dorsal neostriatum on the open-field and shuttle-box behavior were studied in rats with high (Koltushi high avoidance, KHA) and low (Koltushi low avoidance, KLA) capability for avoidance learning. The effects of this hormone on the behavior of these rat strains were different. In KLA rats with passive strategy of behavior the CRH injection led to a rapid locomotor activation in the open field, while the rats with active behavioral strategy (KHA) reacted to the injection by a significant decrease in locomotion and change for the passive mode of behavior. The same CRH effects on locomotion were obtained in the shuttle-box experiments. Moreover, in the KLA rats the neurohormone injection resulted in an improvement of avoidance learning in contrast to the KHA rats, in which CRH substantially impaired avoidance learning. The obtained evidence is discussed in terms of the important role of striatal CRH in the choice of behavioral strategy in stress.  相似文献   
89.
90.
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