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   2406篇
  免费   6篇
电工技术   5篇
化学工业   48篇
金属工艺   2篇
机械仪表   9篇
建筑科学   4篇
矿业工程   1篇
能源动力   4篇
轻工业   21篇
水利工程   2篇
无线电   22篇
一般工业技术   51篇
冶金工业   2187篇
原子能技术   1篇
自动化技术   55篇
  2022年   2篇
  2021年   5篇
  2018年   5篇
  2017年   5篇
  2016年   3篇
  2015年   5篇
  2014年   3篇
  2013年   10篇
  2012年   6篇
  2011年   9篇
  2010年   11篇
  2009年   2篇
  2008年   8篇
  2007年   8篇
  2006年   6篇
  2005年   10篇
  2004年   4篇
  2003年   13篇
  2002年   6篇
  2001年   5篇
  2000年   6篇
  1999年   69篇
  1998年   611篇
  1997年   380篇
  1996年   251篇
  1995年   144篇
  1994年   105篇
  1993年   140篇
  1992年   23篇
  1991年   34篇
  1990年   33篇
  1989年   37篇
  1988年   29篇
  1987年   26篇
  1986年   28篇
  1985年   27篇
  1984年   3篇
  1983年   13篇
  1982年   11篇
  1981年   17篇
  1980年   24篇
  1979年   9篇
  1978年   7篇
  1977年   81篇
  1976年   159篇
  1975年   6篇
  1972年   2篇
  1966年   1篇
  1965年   2篇
  1955年   2篇
排序方式: 共有2412条查询结果,搜索用时 15 毫秒
991.
992.
The usefulness and accuracy of CT scanning in the determination of bone mineral content is studied. The radius in 31 patients of both sexes and varying ages was examined using both the Norland-Cameron bone mineral analyzer and the CT scanner. There was reasonably good correlation (r=.72). Ten cadaver bones were then examined with CT scanning and were sent to the laboratory for calcium determination. These results indicate excellent correlation (r=.97). It is concluded that CT scanning represents the only practical and accurate in vivo method of bone mineral content determination.  相似文献   
993.
994.
Serum bile acid levels were determined by a radioimmunoassay for conjugates of cholic acid in 18 patients with biopsy-proved cirrhosis and compared to results of conventional liver function tests. Serum bile acid levels were abnormal in all 18 patients whereas results of the other tests were abnormal in only 50% to 72% of patients. In this group of patients with a well established diagnosis of cirrhosis, serum bile acid levels were a more sensitive indicator of liver dysfunction than standard liver function tests.  相似文献   
995.
This study was undertaken to determine whether the increase in plasma glucagon concentration that occurs in response to prolonged exercise is modified by endurance exercise training. Eight subjects participated in an exercise program, consisting of running and bicycling, 4 days/wk for 10 wk. The training program resulted in an average increase in VO2 max of 18%. The average increase in plasma glucagon during a 60-min long bicycle exercise test that required 60% of the subjects' VO2 max was 107+/-28 pg/ml, from 116+/-14 pg/ml at rest to 223+/-37 pg/ml after 60 min of exercise, prior to training. After training the same absolute work rate resulted in an increase in plasma glucagon of only 20+/-6 pg/ml, from 125+/-20 to 145+/-16 pg/ml (P less than 0.02). A similar blunting of the glucagon response to exercise was seen during work of the same relative intensity after training. Plasma insulin concentration decreased from 18.1+/-2.5 to 7.6+/-1.6 muunits/ml during the 60 min of exercise before training. A similar decrease in insulin concentration was seen at the same relative work rate after training. However, the decrease in plasma insulin at the same absolute work rate, from 18.5+/-3.0 to 12.5+/-1.8 muunits/ml, was significantly smaller after training (P less than 0.05).  相似文献   
996.
Nuclear magnetic resonance (NMR) method for the quantitative analysis of cyclopropenoid fatty acids (CPFA) in lipids is described. Good accuracy is obtained at CPFA concentrations of 1% to 100%. At a CPFA concentration of 10%, NMR is accurate to 0.5%. The position of absorption of the two ring methylene hydrogens is solvent dependent.  相似文献   
997.
998.
999.
1000.
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