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   225166篇
  免费   16089篇
  国内免费   826篇
耳鼻咽喉   2391篇
儿科学   5858篇
妇产科学   4504篇
基础医学   29498篇
口腔科学   4790篇
临床医学   21242篇
内科学   47965篇
皮肤病学   3211篇
神经病学   21887篇
特种医学   7562篇
外国民族医学   13篇
外科学   35135篇
综合类   3459篇
现状与发展   2篇
一般理论   298篇
预防医学   19775篇
眼科学   4856篇
药学   15427篇
  1篇
中国医学   390篇
肿瘤学   13817篇
  2023年   920篇
  2022年   1535篇
  2021年   3692篇
  2020年   2272篇
  2019年   3591篇
  2018年   4228篇
  2017年   3454篇
  2016年   3731篇
  2015年   4393篇
  2014年   6569篇
  2013年   9374篇
  2012年   14019篇
  2011年   15231篇
  2010年   8721篇
  2009年   7883篇
  2008年   14576篇
  2007年   15461篇
  2006年   14942篇
  2005年   15441篇
  2004年   14744篇
  2003年   13794篇
  2002年   13321篇
  2001年   2140篇
  2000年   1643篇
  1999年   2266篇
  1998年   3041篇
  1997年   2587篇
  1996年   2340篇
  1995年   2079篇
  1994年   1845篇
  1993年   1762篇
  1992年   1291篇
  1991年   1234篇
  1990年   1136篇
  1989年   1032篇
  1988年   1110篇
  1987年   1091篇
  1986年   1067篇
  1985年   1143篇
  1984年   1530篇
  1983年   1519篇
  1982年   1879篇
  1981年   1675篇
  1980年   1598篇
  1979年   850篇
  1978年   999篇
  1977年   974篇
  1976年   870篇
  1975年   711篇
  1974年   705篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
42.
43.
Advance directives such as living wills are attractive in that they give us a sense of control over our futures. But they also tend to obscure conflicts between a patient's competent wishes and later, incompetent interests. They allow caregivers to avoid evaluating quality of life in assessing the best interests of incompetent patients.  相似文献   
44.
Reactive oxygen species: a breath of life or death?   总被引:7,自引:0,他引:7  
New insights into cancer cell-specific biological pathways are urgently needed to promote development of rationally targeted therapeutics. Reactive oxygen species (ROS) and their role in cancer cell response to growth factor signaling and hypoxia are emerging as verdant areas of exploration on the road to discovering cancer's Achilles heel. One of the distinguishing and near-universal hallmarks of cancer growth is hypoxia. Unregulated cellular proliferation leads to formation of cellular masses that extend beyond the resting vasculature, resulting in oxygen and nutrient deprivation. The resulting hypoxia triggers a number of critical adaptations that enable cancer cell survival, including apoptosis suppression, altered glucose metabolism, and an angiogenic phenotype. Ironically, recent investigations suggest that oxygen depletion stimulates mitochondria to elaborate increased ROS, with subsequent activation of signaling pathways, such as hypoxia inducible factor 1alpha, that promote cancer cell survival and tumor growth. Because mitochondria are key organelles involved in chemotherapy-induced apoptosis induction, the relationship between mitochondria, ROS signaling, and activation of survival pathways under hypoxic conditions has been the subject of increased study. Insights into mechanisms involved in ROS signaling may offer novel avenues to facilitate discovery of cancer-specific therapies. Preclinical and clinical evaluation of agents that modify ROS signaling in cancer offers a novel avenue for intervention. This review will cover recent work in ROS-mediated signaling in cancer cells and its potential as a target for developmental therapeutics.  相似文献   
45.
46.
47.
48.
49.
50.
OBJECTIVE: To assess the impact of activity restriction (AR) on the incidence of preterm birth in women treated for preterm labor testing negative for fetal fibronectin (fFN). STUDY DESIGN: Women who were diagnosed with preterm labor and tocolyzed with magnesium sulfate were concurrently screened with fFN for the purpose of subsequent management. Included were consenting patients with negative fFN, gestational age 23 0/7-33 6/7 weeks, cervical dilation < or =3 cm, and minimal vaginal bleeding. Patients were randomized to AR or no AR. Primary study outcome was incidence of preterm delivery and interval from randomization to delivery. RESULTS: A total of 73 women with negative fFN were randomized (36 with AR, 37 without AR). The overall preterm birth rate was 40%, with 44.4% of patients with AR and 35.1% of patients without AR delivering preterm, p=0.478. CONCLUSION: Maternal AR did not impact pregnancy outcome. The incidence of preterm birth in symptomatic women testing fFN negative was higher than previously reported.  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