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   3714401篇
  免费   304366篇
  国内免费   34229篇
耳鼻咽喉   50212篇
儿科学   108826篇
妇产科学   93707篇
基础医学   573886篇
口腔科学   100133篇
临床医学   342791篇
内科学   649948篇
皮肤病学   94781篇
神经病学   310169篇
特种医学   146708篇
外国民族医学   650篇
外科学   563679篇
综合类   147843篇
现状与发展   96篇
一般理论   2288篇
预防医学   297435篇
眼科学   87014篇
药学   268554篇
  322篇
中国医学   25371篇
肿瘤学   188583篇
  2022年   33670篇
  2021年   67615篇
  2020年   44916篇
  2019年   66263篇
  2018年   79100篇
  2017年   61570篇
  2016年   66724篇
  2015年   84631篇
  2014年   121254篇
  2013年   184032篇
  2012年   107523篇
  2011年   109370篇
  2010年   127047篇
  2009年   129257篇
  2008年   89280篇
  2007年   92620篇
  2006年   103484篇
  2005年   99247篇
  2004年   95838篇
  2003年   86548篇
  2002年   75787篇
  2001年   113268篇
  2000年   107266篇
  1999年   106725篇
  1998年   68687篇
  1997年   66524篇
  1996年   63475篇
  1995年   58708篇
  1994年   52537篇
  1993年   48614篇
  1992年   73488篇
  1991年   69524篇
  1990年   66275篇
  1989年   65418篇
  1988年   61154篇
  1987年   59616篇
  1986年   56897篇
  1985年   56451篇
  1984年   50755篇
  1983年   45933篇
  1982年   42402篇
  1981年   39892篇
  1980年   37693篇
  1979年   43009篇
  1978年   37352篇
  1977年   34266篇
  1976年   31033篇
  1975年   30688篇
  1974年   32403篇
  1973年   31074篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
993.
Several million American children are currently unsupervised during the hours between school and parents' leaving for and/or return from the workplace. Many families would prefer other arrangements, but cost or availability factors present insurmountable barriers. Although growing, the public response continues to fall far short of the need; in the meantime, private entrepreneurs are moving to fill the gaps in available services. But if these programs for school-aged children are to serve functions other than the aggrandizement of their sponsors, they must be focused on the real needs that exist among real American children. Among the real children in need of care are those who are impoverished, unsupervised, unfit physically, unprepared for the demands of school and workplace, hurried into premature adulthood, and/or disconnected from the social worlds around them. Professional child and youth care workers with experience in day care and residential settings have the preparation needed to take leadership roles in creating developmentally appropriate, effective programs to meet the emerging demands for school-age child care and to weave them into a fabric of youth-centered community services.  相似文献   
994.
995.
Post-traumatic retinal detachment occurs frequently as a late consequence of progressive vitreous changes, especially following penetrating injuries. Occasionally, it develops soon after the trauma, without preceding proliferative vitreoretinopathy, is based on posterior vitreous detachment and morphologically resembles an idiopathic retinal detachment. It is possible that the posterior vitreous detachment in these cases is encouraged by the presence of intravitreal hemorrhage.  相似文献   
996.
997.
998.
An exaggerated fall in blood pressure has been reported with the combination of an alpha 1-blocker and a calcium antagonist. This study investigated, in a placebo-controlled, randomized crossover trial, the clinical usefulness of the combination of prazosin (2 mg b.i.d.) and verapamil (160 mg b.i.d.). Therapeutic efficacy was monitored at regular outpatient visits: average supine and erect blood pressures were, respectively, 175/99 and 176/103 mm Hg with placebo, 160/91 and 164/96 mm Hg with single drug treatment, and 152/84 and 152/89 mm Hg with combination therapy. This significant and clinically useful reduction in blood pressure had an overall magnitude of approximately 28/18 mm Hg (supine) and 29/19 mm Hg (erect). Further measurements were made during a series of intensive study days, and the most important additional finding was a pharmacokinetic interaction that resulted in increased peak concentrations and bioavailability of prazosin. In conclusion, the combination of prazosin and verapamil proved effective in the treatment of 12 patients with essential hypertension who had been poorly responsive to conventional treatment with a beta-blocker and thiazide diuretic.  相似文献   
999.
Do brain systems exist which control not only increases or decreases in food intake, but also bring about specific changes in the size and distribution of meals consumed, alter the selection of particular macronutrients and adjust feeding responses to the perceived pleasantness (hedonic value) of the food? A cautious yes can be given to each of these questions. Moreover, since most experimental work has been carried out on the brains of animals, we can also ask how well these animal data relate to the human condition; given the methodological issues involved in making such inferences, the answer is remarkably well.  相似文献   
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