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   2502599篇
  免费   172394篇
  国内免费   3335篇
耳鼻咽喉   33032篇
儿科学   81881篇
妇产科学   65394篇
基础医学   362416篇
口腔科学   65052篇
临床医学   221890篇
内科学   483861篇
皮肤病学   52324篇
神经病学   199400篇
特种医学   95952篇
外国民族医学   489篇
外科学   379122篇
综合类   49729篇
现状与发展   12篇
一般理论   848篇
预防医学   198110篇
眼科学   56831篇
药学   183454篇
  11篇
中国医学   5198篇
肿瘤学   143322篇
  2021年   18988篇
  2019年   19550篇
  2018年   46229篇
  2017年   35540篇
  2016年   39752篇
  2015年   26418篇
  2014年   36739篇
  2013年   54548篇
  2012年   80731篇
  2011年   97757篇
  2010年   63257篇
  2009年   54678篇
  2008年   91497篇
  2007年   98395篇
  2006年   80725篇
  2005年   79584篇
  2004年   77407篇
  2003年   75549篇
  2002年   71592篇
  2001年   108976篇
  2000年   111810篇
  1999年   93629篇
  1998年   27158篇
  1997年   23844篇
  1996年   24107篇
  1995年   22806篇
  1994年   20977篇
  1993年   19763篇
  1992年   72035篇
  1991年   70157篇
  1990年   68513篇
  1989年   65732篇
  1988年   60349篇
  1987年   59158篇
  1986年   55240篇
  1985年   53028篇
  1984年   39331篇
  1983年   33422篇
  1982年   19881篇
  1979年   35872篇
  1978年   25658篇
  1977年   21234篇
  1976年   20340篇
  1975年   21821篇
  1974年   26167篇
  1973年   24806篇
  1972年   23200篇
  1971年   22037篇
  1970年   20263篇
  1969年   19334篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Background: In elderly patients, opioids may cause prominent postoperative sedation and respiratory depression. We evaluated the influence of age on the effects of opioids and plasma concentrations of fentanyl and oxycodone in cardiac surgery patients.
Methods: Thirty (≥75 years, gender M9/F21) and 20 (≤60 years, gender M20/F0) patients scheduled to undergo cardiac surgery. A standard anesthesia with fentanyl as an opioid was used. Fentanyl plasma concentrations were measured at the end of surgery and 2 h later. After tracheal extubation, when the pain intensity was at least moderate, blood samples for fentanyl and oxycodone plasma concentration measurements were taken. Thereafter, oxycodone hydrochloride 0.05 mg/kg i.v. was administered. After 15 and 45 min, pain intensity, sedation and oxycodone plasma concentration were determined. This test protocol was repeated twice.
Results: The elderly had a higher plasma concentration of fentanyl at the end of surgery than younger patients (5.7±2.2 vs. 3.8±1.2 ng/ml, P =0.001). The plasma concentrations of oxycodone were comparable between the groups. The interval between the second and the third oxycodone dose was longer in the elderly patients ( P =0.036). Pain intensity on the verbal rating scale was lower at the 45-min assessment point after all three oxycodone test doses ( P =0.008) and sedation scores were significantly higher after the third dose in the elderly patients ( P =0.035).
Conclusions: In elderly patients, the plasma concentration of fentanyl was higher but plasma levels of oxycodone were at a similar level compared with middle-aged patients. However, the elderly patients had less pain and were more sedated after doses of oxycodone.  相似文献   
992.
993.
994.
995.
996.
997.
998.
Background  Psoriasis is a chronic disease characterized by abnormal epidermal proliferation, inflammation and angiogenesis. It has been reported that vascular endothelial growth factor (VEGF) is overexpressed in lesional psoriatic skin and its serum levels are significantly elevated in patients with moderate to severe disease.
Objective  This study aims to evaluate the possible role of VEGF in the pathogenesis of psoriasis, and its significance as an indicator of disease severity and control.
Methods  Thirty patients with moderate to severe psoriasis and 10 healthy controls were subjected to baseline evaluation of VEGF. Patients were divided into three groups according to the received treatment: psoralen plus ultraviolet A (PUVA) thrice weekly (group 1), acitretin 50 mg daily (group 2), and combined PUVA twice weekly and acitretin 25 mg daily (group 3).Treatment continued for 16 weeks or up to clinical cure. Every patient was subjected to severity evaluation by Psoriasis Area and Severity Index (PASI) and measurement of serum VEGF before and after treatment.
Results  Mean serum levels of VEGF were significantly elevated in patients (327 ± 66.2 pg/mL) than control subjects (178 ± 83.4 pg/mL). A highly significant correlation was found between VEGF and PASI score, but not with other variables. The best clinical response, the least side-effects and the highest reduction of VEGF serum levels were achieved by the combined therapy.
Conclusion  The present study supported the proposed role of VEGF in the pathogenesis of psoriasis, and suggested that it could serve as a good indicator of disease severity and control.  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