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   473714篇
  免费   54626篇
  国内免费   738篇
  2018年   4511篇
  2017年   4310篇
  2016年   6284篇
  2015年   9137篇
  2014年   10586篇
  2013年   14184篇
  2012年   16935篇
  2011年   17265篇
  2010年   11386篇
  2009年   10398篇
  2008年   15176篇
  2007年   15502篇
  2006年   14576篇
  2005年   13860篇
  2004年   13904篇
  2003年   13036篇
  2002年   12680篇
  2001年   19567篇
  2000年   19466篇
  1999年   15631篇
  1998年   5990篇
  1997年   5956篇
  1996年   5704篇
  1995年   5429篇
  1994年   5126篇
  1993年   5147篇
  1992年   12984篇
  1991年   12892篇
  1990年   12635篇
  1989年   12146篇
  1988年   11236篇
  1987年   10658篇
  1986年   10100篇
  1985年   9966篇
  1984年   8275篇
  1983年   7149篇
  1982年   5467篇
  1981年   4921篇
  1980年   4590篇
  1979年   7690篇
  1978年   6266篇
  1977年   5565篇
  1976年   5218篇
  1975年   6024篇
  1974年   6598篇
  1973年   6396篇
  1972年   5676篇
  1971年   5297篇
  1970年   4473篇
  1969年   4393篇
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
101.
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   
102.
103.
104.
105.
106.
107.
Samples of marine pleuston were collected from the sea-surface along considerable sections of the track of Eye of the Wind during its 2-year circumnavigational expedition 'Operation Drake' from November 1978 to October 1980. One hundred and eleven of the tow samples contained insects of the genus Halobates . They were assigned to four oceanic species: H. micans, H. sericeus, H. germanus and H. splendens; two coastal species: H. maculatus, H. princeps, and one undescribed species. Various development stages of the oceanic species were found. The locations, time of collection and surface temperatures where sea-skaters were collected are tabulated. Distributional boundaries and population densities of the oceanic species collected are discussed.  相似文献   
108.
109.
Rosette and single-element strain gauges were implanted on the tibia in 2 dogs and recordings were made during locomotion on a treadmill. At foot contact and during the swing phase of locomotion, bone strains were low and directions of the principal strains were variable. There was a large shift in the directions of the principal strains at the beginning of the stance phase and bone strains were considerably higher. Peak strain occurred midway through the stance phase. At that time, the maximum principal strain (tension) was directed upwards and anteriorly between 30 and 60 degrees with respect to the long axis of the tibia. These bone strain patterns in the dog are similar to those found in sheep while both differ markedly from those found in humans.  相似文献   
110.
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