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   913篇
  免费   109篇
  2022年   11篇
  2021年   17篇
  2020年   10篇
  2019年   15篇
  2018年   13篇
  2017年   13篇
  2016年   27篇
  2015年   46篇
  2014年   35篇
  2013年   49篇
  2012年   47篇
  2011年   45篇
  2010年   36篇
  2009年   23篇
  2008年   35篇
  2007年   25篇
  2006年   44篇
  2005年   34篇
  2004年   38篇
  2003年   30篇
  2002年   29篇
  2001年   15篇
  2000年   31篇
  1999年   15篇
  1998年   14篇
  1997年   9篇
  1996年   8篇
  1995年   7篇
  1994年   10篇
  1992年   18篇
  1991年   15篇
  1990年   10篇
  1989年   16篇
  1987年   14篇
  1986年   7篇
  1985年   14篇
  1984年   11篇
  1983年   8篇
  1982年   9篇
  1981年   10篇
  1980年   13篇
  1979年   11篇
  1978年   12篇
  1975年   8篇
  1974年   7篇
  1973年   9篇
  1971年   7篇
  1970年   12篇
  1969年   7篇
  1967年   6篇
排序方式: 共有1022条查询结果,搜索用时 15 毫秒
981.
982.
The flush technique that recently has come into use is probably the most satisfactory method available for measuring blood pressures in infants and is of great aid in diagnosis of diseases associated with hypertension or hypotension. The method is practical and highly accurate. Readings obtained by this technique are not influenced by the width of the cuff, are usually higher at the wrist than at the ankle, and approximate the mean rather than the systolic blood pressure.  相似文献   
983.
984.
Wild and game-farm mallards (Anas platyrhynchos) raised in pure strain and mixed groups were tested for initial mate preference in a choice test. Female mallards showed no significant preference but males of either strain raised with females of their own strain significantly preferred female models of their own strain during the test. Males raised with females of the other strain merely showed attenuation of their preference for female models of their own strain and did not show preference for female models of the other strain. Game-farm mallards approached models significantly sooner than wild mallards and there was a significant sex × mate interaction.  相似文献   
985.
We have mapped the chromosomal location of four genes previously assigned to human chromosome 21--Cu/Zn superoxide dismutase (SOD1), the protooncogene ETS2, the interferon alpha/beta receptor gene (IFNAR), and the carbonyl reductase gene (CBR)--in the tammar, Macropus eugenii. The genes are localized on two separate autosomes: SOD1 and CBR map to chromosome 7 and ETS2 and IFNAR map to chromosome 3 or 4. These results provide the first example of asynteny between SOD1/CBR and ETS2/IFNAR in a mammalian species. The results suggest that either this synteny group has been disrupted in the marsupial lineage, or, alternatively, the genes located on human chromosome 21 may have been joined after the marsupials diverged from the eutherian mammals some 130-150 million years ago.  相似文献   
986.
987.
988.
Mean plasma 17-beta-estradiol (E2) concentrations of nonphotostimulated adult bobwhite quail were less than 31.2 and 119.9 pg/ml for males and females, respectively. Dietary beta-estradiol-3-benzoate (E2 beta) dosages of 10, 100 or 500 micrograms/bird/day caused mean plasma E2 concentrations of females to increase by 1.2, 2.0 or 5.6 times. Oviduct weights were significantly increased in females fed E2 beta dosages of greater than 100 micrograms/bird/day for five days. Gonad weights were not significantly effected in either sex. Ten- to fifty-fold greater doses of dietary E2 beta were required to induce oviduct growth responses equivalent to those produced by injected E2 beta.  相似文献   
989.
Glucose dehydrogenase from A. calcoaceticus has been dissociated into apoenzyme and methoxatin coenzyme, and enzyme activity restored by replacing coenzyme with 4,7-phenanthroline-5,6-dione but not with 1,10- nor 1,7-phenanthroline-5,6-diones nor with 7,9-decarboxy methoxatin.  相似文献   
990.
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