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   3494836篇
  免费   285297篇
  国内免费   13996篇
耳鼻咽喉   48704篇
儿科学   112501篇
妇产科学   91722篇
基础医学   551456篇
口腔科学   93830篇
临床医学   312750篇
内科学   618468篇
皮肤病学   91888篇
神经病学   296323篇
特种医学   137426篇
外国民族医学   392篇
外科学   542963篇
综合类   103129篇
现状与发展   23篇
一般理论   2278篇
预防医学   293514篇
眼科学   79740篇
药学   242031篇
  23篇
中国医学   9844篇
肿瘤学   165124篇
  2021年   55318篇
  2020年   35317篇
  2019年   58429篇
  2018年   71825篇
  2017年   54728篇
  2016年   60328篇
  2015年   74542篇
  2014年   108931篇
  2013年   174538篇
  2012年   93598篇
  2011年   94251篇
  2010年   117618篇
  2009年   121927篇
  2008年   82045篇
  2007年   85862篇
  2006年   96488篇
  2005年   92501篇
  2004年   94110篇
  2003年   85230篇
  2002年   75421篇
  2001年   104817篇
  2000年   97476篇
  1999年   97696篇
  1998年   65513篇
  1997年   63149篇
  1996年   61105篇
  1995年   56512篇
  1994年   50797篇
  1993年   47260篇
  1992年   69801篇
  1991年   67021篇
  1990年   64379篇
  1989年   63528篇
  1988年   59515篇
  1987年   57961篇
  1986年   55272篇
  1985年   55230篇
  1984年   49811篇
  1983年   45819篇
  1982年   42251篇
  1981年   39724篇
  1980年   37418篇
  1979年   41890篇
  1978年   36537篇
  1977年   33457篇
  1976年   30822篇
  1975年   30078篇
  1974年   31309篇
  1973年   30102篇
  1972年   28364篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
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   
992.
993.
994.
Tear mucus crystallization in children with cystic fibrosis   总被引:1,自引:0,他引:1  
Cystic fibrosis is characterized by an abnormally high electrolyte concentration in exocrine secretions. The authors performed the tear mucus ferning test in 26 eyes of children with cystic fibrosis and compared the results to those in an equal number of age-matched normals. The results suggest that the increased electrolyte concentration could be responsible for the increased hyperviscosity of mucus. The tear mucus ferning test appears to be a suitable diagnostic test for the assessment of cystic fibrosis.  相似文献   
995.
996.
997.
In this graphite-furnace atomic-absorption spectrometric method for measuring manganese in whole blood, we use a pyrolytic platform to minimize interference by sample matrix. For optimal sample ashing we denature the sample within the furnace with nitric acid and use oxygen as the purge gas at low temperatures. The mean manganese concentration found in blood from 15 unexposed city dwellers was 215 (2 SD 135) nmol/L. By comparison, the range of manganese concentrations in blood sampled from a group of Australian aborigines living near a surface manganese ore deposit on Groote Eylandt, Northern Territory, was much higher (median 405 nmol/L, range 175 to 990 nmol/L).  相似文献   
998.
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   
999.
1000.
【目的】探讨地塞米松的用药方式对孕妇糖代谢的影响。【方法】对 1999年 9月至 2 0 0 1年 1月在本院住院的15 0名不同用药方式使用地塞米松促胎儿肺成熟的孕妇进行研究 ,在用药前及用药后 18~ 2 4h抽取肘前静脉血查空腹血糖、血浆C肽 ,糖负荷后 2h血糖、血浆C肽。【结果】使用地塞米松后 ,空腹血糖值、糖负荷后 2h血糖值、空腹C肽及糖负荷后 2hC肽值较用药前高 ;用药方式对母体空腹血糖值和空腹C肽值的影响差异无统计学意义 (P >0 0 5 ) ,对母体糖负荷后 2h血糖值和糖负荷后 2hC肽值的影响差异有统计学意义 (P <0 0 5 ) ;不同糖代谢状态的受试者使用地塞米松后 ,空腹C肽值、糖负荷后 2hC肽值的改变差异有统计学意义 (P <0 0 5 )。【结论】孕妇使用地塞米松促胎儿肺成熟对母体的糖代谢均有一定程度的影响 ,用药过程中和用药后需严密监测母体血糖和胎儿宫内状况  相似文献   
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