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   212436篇
  免费   15352篇
  国内免费   760篇
耳鼻咽喉   2309篇
儿科学   5527篇
妇产科学   4336篇
基础医学   27362篇
口腔科学   4534篇
临床医学   20176篇
内科学   45361篇
皮肤病学   2775篇
神经病学   20472篇
特种医学   6988篇
外国民族医学   13篇
外科学   33158篇
综合类   3461篇
现状与发展   2篇
一般理论   295篇
预防医学   19226篇
眼科学   4530篇
药学   14523篇
  1篇
中国医学   381篇
肿瘤学   13118篇
  2023年   855篇
  2022年   1420篇
  2021年   3498篇
  2020年   2132篇
  2019年   3439篇
  2018年   4011篇
  2017年   3261篇
  2016年   3442篇
  2015年   4111篇
  2014年   6163篇
  2013年   8922篇
  2012年   13244篇
  2011年   14483篇
  2010年   8172篇
  2009年   7373篇
  2008年   13694篇
  2007年   14550篇
  2006年   14022篇
  2005年   14525篇
  2004年   13932篇
  2003年   13023篇
  2002年   12531篇
  2001年   1983篇
  2000年   1525篇
  1999年   2099篇
  1998年   2841篇
  1997年   2459篇
  1996年   2221篇
  1995年   1962篇
  1994年   1769篇
  1993年   1665篇
  1992年   1237篇
  1991年   1180篇
  1990年   1065篇
  1989年   975篇
  1988年   1032篇
  1987年   1037篇
  1986年   1020篇
  1985年   1095篇
  1984年   1490篇
  1983年   1468篇
  1982年   1821篇
  1981年   1650篇
  1980年   1559篇
  1979年   823篇
  1978年   965篇
  1977年   937篇
  1976年   833篇
  1975年   686篇
  1974年   669篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
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   
33.
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   
34.
35.
36.
37.
38.
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   
39.
40.
Pryor  John 《JAMA》2006,296(19):2379
  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