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   83032篇
  免费   8187篇
  国内免费   201篇
耳鼻咽喉   1181篇
儿科学   2498篇
妇产科学   1787篇
基础医学   11855篇
口腔科学   2010篇
临床医学   10207篇
内科学   14644篇
皮肤病学   1308篇
神经病学   6734篇
特种医学   2898篇
外国民族医学   10篇
外科学   11409篇
综合类   1670篇
一般理论   67篇
预防医学   9480篇
眼科学   1850篇
药学   6785篇
  1篇
中国医学   77篇
肿瘤学   4949篇
  2021年   1111篇
  2020年   738篇
  2019年   1120篇
  2018年   1391篇
  2017年   1001篇
  2016年   1094篇
  2015年   1247篇
  2014年   1633篇
  2013年   2570篇
  2012年   3466篇
  2011年   3745篇
  2010年   1986篇
  2009年   1910篇
  2008年   3231篇
  2007年   3572篇
  2006年   3413篇
  2005年   3480篇
  2004年   3247篇
  2003年   3021篇
  2002年   2956篇
  2001年   2715篇
  2000年   2832篇
  1999年   2516篇
  1998年   1089篇
  1997年   902篇
  1996年   886篇
  1995年   800篇
  1994年   821篇
  1993年   755篇
  1992年   2109篇
  1991年   2027篇
  1990年   1905篇
  1989年   1872篇
  1988年   1782篇
  1987年   1782篇
  1986年   1692篇
  1985年   1674篇
  1984年   1388篇
  1983年   1262篇
  1982年   843篇
  1981年   721篇
  1979年   1215篇
  1978年   878篇
  1977年   773篇
  1976年   723篇
  1975年   717篇
  1974年   859篇
  1973年   752篇
  1972年   733篇
  1971年   640篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
In the sheep, unlike many other species, a significant proportion (>25%) of immunoreactive β-endorphin in the anterior pituitary is post-translationally modified to opioid-inactive, α-N-acetylated forms. In a study to determine the precise molecular nature of α-N-acetylated β-endorphin immunoreactivity, we noted a striking difference in high-performance liquid chromatography profiles of anterior pituitary extracts between sheep killed on the farm, and age-, sex- and strain-matched slaughterhouse animals. These altered patterns of a-N-acetylated β-endorphin processing were reproduced in farm animals by chronic (≤ 4 days) treatment with the synthetic glucocorticoid dexamethasone; in contrast dexamethasone had no effect on a-N-acetylated β-endorphin processing in hypothalamo-pituitary disconnected sheep. These data suggest that (1) the change in processing is a stress response, mediated by prolonged glucocorticoid exposure, (2) this effect is central, rather than a direct effect on the pituitary, and (3) the relative abundance of various peptide sequences in slaughterhouse-derived material may not reflect their abundance under more physiological conditions.  相似文献   
62.
The percentage of peripheral blood lymphocytes forming rosettes with sheep erythrocytes (E-rosettes) was determined in 33 severely malnourished Guatemalan children, and in two groups of clinically well but mildly growth retarded children from the same environment. Mean E-rosettes in the acutely ill patients was lower than the value observed in the mildly malnourished children, although there was considerable overlap between groups. These data differ from previously published studies of severely malnourished children from other parts of the world in that not all patients had decreased values for E-rosettes, in contrast to the uniform depression reported by others. As all patients were clinically similar, the results suggest that there may be specific nutrient defects associated with protein-energy malnutrition that particularly affect immune function. In addition, in vitro incubation of lymphocytes from the acutely malnourished children with the thymic factor, thymosin fraction 5, increased the percentage of E-rosettes in a dose-dependent fashion. These data suggest that immature, thymosin-responsive T cells are present in circulation. It is possible that in vivo thymosin administration may be beneficial for malnourished individuals.  相似文献   
63.
The effects of ethylene glycol monomethyl ether (EGME) on reproductive outcome in the rat, and on ornithine decarboxylase (ODC) activity in the rat embryo were evaluated. Dams (n = 8) were treated by gavage on gestation days 6-12 (sperm = day 0) with 0, 25, 50 or 75 mg/kg EGME in 10 ml/kg distilled water. EGME had a dose-dependent effect on reproductive outcome. Gestation length was prolonged, and the number of litters delivered and neonatal body weight were reduced. Whole embryo ODC was measured on gestation days 9, 11, 13 and 15. ODC attained maximum activity in controls on day 11, increasing by more than an order of magnitude above the activity found on day 9. On day 11, a statistically significant dose-dependent inhibition of ODC activity was observed with the maximum dose of EGME inhibiting ODC activity 60 percent. On days 13 and 15, ODC activity declined markedly from peak values, and the dose-dependent inhibition was no longer evident. The study demonstrates a correlation between the inhibition of embryonic ODC activity by EGME and the effect of EGME on reproductive outcome.  相似文献   
64.
65.
Effect of food on enoxacin absorption.   总被引:5,自引:5,他引:0       下载免费PDF全文
Fifteen subjects received a single 400-mg oral dose of enoxacin in the fasting state and after carbohydrate and high-fat meals. The carbohydrate meal delayed the time to peak enoxacin concentration in plasma by an average of 0.92 h. The extent of enoxacin absorption was not altered by food.  相似文献   
66.
Humor has become a popular topic in health care recently. One of the suggested benefits is to help control pain. Although no scientific research to date has validated this effect, there is some theoretical and empirical support for the use of humor especially with children. Methods to implement the uses of humor in a clinical setting are suggested inappropriate uses of humor are also discussed. The need for scientific research is stressed.  相似文献   
67.
68.
69.
70.
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