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   394286篇
  免费   45386篇
  国内免费   360篇
  2016年   3565篇
  2015年   5341篇
  2014年   6235篇
  2013年   8959篇
  2012年   9936篇
  2011年   10007篇
  2010年   6658篇
  2009年   6290篇
  2008年   8900篇
  2007年   9384篇
  2006年   8927篇
  2005年   8681篇
  2004年   8611篇
  2003年   8208篇
  2002年   8203篇
  2001年   18197篇
  2000年   18752篇
  1999年   14890篇
  1998年   4898篇
  1997年   5159篇
  1996年   4808篇
  1995年   4612篇
  1994年   4547篇
  1993年   4550篇
  1992年   12056篇
  1991年   11642篇
  1990年   11302篇
  1989年   10958篇
  1988年   10344篇
  1987年   9865篇
  1986年   9371篇
  1985年   9458篇
  1984年   7812篇
  1983年   6719篇
  1982年   5347篇
  1981年   4979篇
  1980年   4520篇
  1979年   7626篇
  1978年   6155篇
  1977年   5654篇
  1976年   5339篇
  1975年   5996篇
  1974年   6626篇
  1973年   6569篇
  1972年   6086篇
  1971年   5509篇
  1970年   4757篇
  1969年   4718篇
  1968年   4300篇
  1967年   3616篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
931.
Aminoglutethimide (AG: 750 mg/day) was administered to a patient with idiopathic hyperaldosteronism (IHA) and circadian rhythms in urinary excretion of sodium (UNaV), potassium (UKV), aldosterone (AER) and 17-OHCS were analyzed by the single cosinor method. Urine was collected every 4h for 24h on the day before and on the 1st, 3rd and 7th day of AG administration, and above variables in each sample were determined. Circadian rhythms of 14 patients with primary aldosteronism (PA) who served as controls were also analyzed. In the present case, circadian acrophases in UNaV and AER studied before AG administration occurred at 22(19) and 07(05), respectively. They were similar to those of preoperative PA-patients. Circadian acrophase in UNaV occurred earlier with AG administration and on the 7th day it was at 14(05), a value similar to that of postoperative PA-patients. Circadian mesor in AER decreased remarkably from 4.1 to 0.6 micrograms/4h with AG administration, as did circadian mesor in UKV, whereas circadian mesor and acrophase in 17-OHCS did not change. Thus, the circadian characteristics in urinary variables in the present IHA-case were pathophysiologically similar to those of PA.  相似文献   
932.
933.
934.
935.
Phagocytosis of microspheres in V79 Chinese hamster lung cells was investigated by flow cytometry. Fluorescent microspheres (1.8 micron diameter) were used as the ingesta. Change in the number of V79 cells containing fluorescent microspheres was measured as an index of phagocytic activity. With time there was a sigmoidal increase in cells containing microspheres. The phagocytosis of microspheres is partially explained by two parameters introduced to describe the sigmoidal curves.  相似文献   
936.
937.
The role of introns in evolution   总被引:6,自引:0,他引:6  
J H Rogers 《FEBS letters》1990,268(2):339-343
What are the roles of 'classical' introns in the evolution of nuclear genes, and what was the origin of these introns? Exon shuffling has been important in the evolution of cell surface and extracellular proteins, but the evidence for it in respect of intracellular proteins is weak. Intron distributions imply that some introns have been removed while others have been inserted in the course of evolution: ancestral patterns of introns may thus have been obscured. Recent evidence on the self-splicing and reverse-splicing abilities of Group II introns supports the hypothesis that these could have been the ancestors of classical introns.  相似文献   
938.
939.
940.
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