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   2589884篇
  免费   184589篇
  国内免费   7583篇
耳鼻咽喉   34277篇
儿科学   85227篇
妇产科学   71609篇
基础医学   363757篇
口腔科学   69714篇
临床医学   234657篇
内科学   516014篇
皮肤病学   62478篇
神经病学   213538篇
特种医学   99954篇
外国民族医学   736篇
外科学   386896篇
综合类   50398篇
现状与发展   5篇
一般理论   968篇
预防医学   196299篇
眼科学   56677篇
药学   188096篇
  8篇
中国医学   5333篇
肿瘤学   145415篇
  2021年   20022篇
  2019年   20650篇
  2018年   29333篇
  2017年   22618篇
  2016年   26259篇
  2015年   29538篇
  2014年   40487篇
  2013年   60485篇
  2012年   80364篇
  2011年   84640篇
  2010年   51073篇
  2009年   49196篇
  2008年   79132篇
  2007年   83955篇
  2006年   85676篇
  2005年   81833篇
  2004年   78812篇
  2003年   76130篇
  2002年   73429篇
  2001年   128436篇
  2000年   131372篇
  1999年   110530篇
  1998年   31277篇
  1997年   27940篇
  1996年   28233篇
  1995年   27401篇
  1994年   25083篇
  1993年   23437篇
  1992年   85190篇
  1991年   81589篇
  1990年   78813篇
  1989年   76090篇
  1988年   69507篇
  1987年   68015篇
  1986年   63583篇
  1985年   60535篇
  1984年   44953篇
  1983年   37957篇
  1982年   22460篇
  1981年   19993篇
  1979年   38973篇
  1978年   27446篇
  1977年   23256篇
  1976年   21502篇
  1975年   22817篇
  1974年   26795篇
  1973年   25379篇
  1972年   23753篇
  1971年   21958篇
  1970年   20185篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
This study investigated social interactions between infants and mothers, comparing dyads with physically disabled infants and dyads with nondisabled infants. The groups were matched on mental and motor development, sex, socioeconomic status, birth order, and maternal education. Each infant-mother dyad was videotaped at home during a 10-minute period of free play, and blind observers subsequently transcribed infants' and mothers' behaviors. In general, the groups were remarkably similar in their interaction patterns. However, a few differences emerged: Mothers of infants with physical disabilities were significantly more commanding than were comparison mothers. Nondisabled infants tended to engage in more eye contact than did infants with physical disabilities. And whereas mothers of nondisabled infants responded to interactive play with interactive play, mothers of infants with physical handicaps tended to respond with commands and verbalizations. These results suggest reciprocal influences between infants and mothers in both groups and highlight emerging maternal behavior patterns that may interfere with the development of communication and independence in handicapped young children.  相似文献   
992.
993.
994.
Wheat germ agglutinin (WGA) was found to stimulate DNA synthesis in human peripheral blood mononuclear cells at relatively low concentrations and to inhibit DNA synthesis at higher concentrations. Both actions were inhibited by oligomers of N-acetyl-D-glucosamine. Significant mitogenic activity was dependent on the use of human (as opposed to fetal calf) serum to supplement the culture medium. Purified T cells responded to WGA very weakly and the incorporation of thymidine into non-T cells in response to WGA was less than the lectin-free control. The full ability of T cells to respond to WGA was restored by the addition of monocytes, but not by any other blood cells. Interleukin 2 partially restored the ability of T cells to respond to WGA; interleukin 1 was less effective. WGA displayed a strong synergistic action with the tumour promoter, 12-O-tetradecanoyl-13-acetate (TPA), in stimulating DNA synthesis in separated T (but not non-T) cell fractions, and in unfractioned mononuclear cells. These results reconcile most of the conflicting reports in the literature concerning the interaction of WGA with human lymphocytes.  相似文献   
995.
A cohort of 1163 pregnant women in two small towns in South Wales, UK, was identified and followed until the children born to them were five years of age. Growth in these children is described and a number of determinants identified. Social-class differences were very small at birth but differences in height became clear by the age of two years and in head circumference before this. In height the differences were largely accounted for by greater growth in social class I, but there was a gradient in head circumference throughout all the social classes. The social class effects gradually increased as the children became older. Parity of the mothers had a small effect on size at birth but age of the mother had no effect once parity was allowed for. Data on illnesses in the children were collected but no effect on growth could be detected. By far the most important determinant of growth which could be controlled is maternal smoking. About 40% of the women smoked, about 17% heavily (15 or more cigarettes per day) and the prevalence of smoking altered little during pregnancy. There was a graded effect of smoking on growth up to a 9% deficit in birth-weight, a 2% deficit in length at birth and a 1.5% deficit in head circumference in the babies born to the mothers who smoked most heavily (25 or more cigarettes per day) compared with non-smokers. There effects decreased with age but there were still residual effects at age five years.  相似文献   
996.
997.
998.
After admission to hospital for bed rest, 200 women with multiple pregnancies were randomly allocated to receive either 4 mg of salbutamol orally five times daily, or to receive no drug. After an average of 6 weeks treatment, no difference between the experimental groups could be detected with respect to duration of gestation, birthweight or any other of the outcomes of pregnancy observed.  相似文献   
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