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   408032篇
  免费   38998篇
  国内免费   232篇
  2018年   3774篇
  2017年   3791篇
  2016年   6529篇
  2015年   11001篇
  2014年   11534篇
  2013年   13886篇
  2012年   14475篇
  2011年   11897篇
  2010年   8765篇
  2009年   8058篇
  2008年   9427篇
  2007年   9814篇
  2006年   9138篇
  2005年   14564篇
  2004年   13056篇
  2003年   11138篇
  2002年   8819篇
  2001年   18971篇
  2000年   18642篇
  1999年   15260篇
  1998年   4514篇
  1997年   4637篇
  1996年   4391篇
  1995年   4134篇
  1994年   4074篇
  1993年   3881篇
  1992年   12943篇
  1991年   12672篇
  1990年   12310篇
  1989年   11824篇
  1988年   11064篇
  1987年   10327篇
  1986年   9378篇
  1985年   9299篇
  1984年   7293篇
  1983年   6266篇
  1982年   4490篇
  1981年   3961篇
  1980年   3661篇
  1979年   6988篇
  1978年   5191篇
  1977年   4638篇
  1976年   4271篇
  1975年   5075篇
  1974年   5327篇
  1973年   5275篇
  1972年   4900篇
  1971年   4300篇
  1970年   3885篇
  1969年   3691篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
The neutrophil-stimulating properties of 38 S. aureus strains and 32 S. epidermidis strains were studied in the reaction of luminol-mediated chemiluminescence. All S. aureus strains and 29 S. epidermidis strains were found to possess neutrophil-stimulating activity, the mean activity index for S. aureus being significantly higher. The stimulating activity of the strains varied within a wide range (the variation coefficient was 120.0 +/- 21.9%) and did not correlate with the content of protein A in bacterial cells and the degree of their hydrophoby. The opsonization of staphylococci with normal human serum enhanced the neutrophil reaction 1.5- to 100-fold and simultaneously leveled out the chemiluminescence indices in experiments with different strains (the variation coefficient was 8.0 +/- 1.5%). The nature of the neutrophil-stimulating effect of staphylococci and its relationship to the exploratory reactions of phagocytes are discussed.  相似文献   
82.
83.
84.
—A resolution of the enhancement of protein synthesis in the visual cortex of rats during first exposure to light (Richardson and Rose , 1972) was achieved by polyacrylamide gel electrophoresis using a double-labelling technique. Differential incorporation of lysine was established between exposed and control animals in two fractions of the soluble proteins and seven fractions of the insoluble proteins. This suggests that exposure to a new experience of this type involves a specific effect on protein synthesis, rather than a general stimulation across all fractions.  相似文献   
85.
86.
87.
88.
89.
90.
Convenient extraction and radioimmunoassay methods for measurement of leukotrienes C4 and D4 (LTC4 and LTD4) in biological fluids are described. LTC4 or LTD4 in plasma was extracted with acetonitrile, and the extract was washed with dichloromethane then adjusted to pH 3.5 or 6.0, respectively. Each leukotriene was partially purified by using a C18-bonded silica cartridge and quantitated by radioimmunoassay. Amounts of LTC4 and LTD4 in the range of 0.025-1.6 ng could be assayed in plasma. This procedure was employed to examine the increase in plasma LTC4 (0.249 +/- 0.036 ng/ml) and LTD4 (1.399 +/- 0.235 ng/ml) of guinea pigs during intravenous challenge-induced anaphylactic bronchoconstriction, and the suppression of the increase of bronchoconstriction and leukotrienes by the administration of 5-lipoxygenase inhibitors such as E6080 (6-hydroxy-2-(4-sulfamoylbenzyl-amino)- 4,5,7-trimethylbenzothiazole hydrochloride), AA861 (2,3,5-trimethyl-6-(12-hydroxy-5,10-dodecadiynyl)-1,4-benzoquinone ) and phenidone. On the other hand, LTC4 and LTD4 were not detected in plasma after an inhaled challenge, though significant bronchoconstriction was provoked. It was concluded that the present study validates a new technique for quantitating plasma leukotrienes on the basis of pH and a suitable method for evaluating the pharmacological efficacy of 5-lipoxygenase inhibitors.  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