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   1277311篇
  免费   99884篇
  国内免费   1992篇
耳鼻咽喉   18434篇
儿科学   44366篇
妇产科学   35019篇
基础医学   182255篇
口腔科学   33612篇
临床医学   111305篇
内科学   258304篇
皮肤病学   28030篇
神经病学   100423篇
特种医学   51238篇
外国民族医学   660篇
外科学   196481篇
综合类   27054篇
现状与发展   1篇
一般理论   381篇
预防医学   95755篇
眼科学   27916篇
药学   94880篇
  2篇
中国医学   2422篇
肿瘤学   70649篇
  2018年   13140篇
  2017年   9971篇
  2016年   10906篇
  2015年   12379篇
  2014年   17177篇
  2013年   26236篇
  2012年   36043篇
  2011年   38089篇
  2010年   22819篇
  2009年   21829篇
  2008年   36680篇
  2007年   39282篇
  2006年   39526篇
  2005年   38463篇
  2004年   37611篇
  2003年   36465篇
  2002年   35811篇
  2001年   63999篇
  2000年   66505篇
  1999年   56423篇
  1998年   15134篇
  1997年   13758篇
  1996年   14201篇
  1995年   13459篇
  1994年   12773篇
  1993年   11798篇
  1992年   44562篇
  1991年   43475篇
  1990年   42222篇
  1989年   40126篇
  1988年   36911篇
  1987年   36249篇
  1986年   33636篇
  1985年   32305篇
  1984年   24147篇
  1983年   20277篇
  1982年   11728篇
  1981年   10698篇
  1980年   9520篇
  1979年   21355篇
  1978年   14827篇
  1977年   12541篇
  1976年   11697篇
  1975年   12633篇
  1974年   14671篇
  1973年   14127篇
  1972年   12948篇
  1971年   11734篇
  1970年   11055篇
  1969年   10026篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Aim:   In the last three decades, the segment of population aged 60 years and older has more than doubled in Brazil. People aged 80 years and older are expected to be the fastest-growing segment in the near future. This aim of this study was to analyze the legal structures currently in place in Brazil and to provide a framework for care policies and practices towards older-adults.
Methods:   This article focuses on past and present major socioeconomic burdens on this segment of the Brazilian population as well as on public achievements to overcome inequities.
Results:   Both the public health and the social security systems have been directed to provide preferential assistance to the aged. Nonetheless, the elderly remain the most impoverished segment of Brazil and carry the burden of an overall lack of specialized services. Moreover, socioeconomic inequalities and population diversity in Brazil affects elderly care, adding complexity to this unique scenario.
Conclusion:   Brazil has adopted legal hallmarks that substantially shifted public practices towards the elderly segment from a philanthropic status to a legitimate right for care and assistance. The demographic transition that took place provides an opportunity for innovative solutions in public policies for older adults in a developing economic environment.  相似文献   
992.
993.
994.
995.
996.
We provide further evidence for the two-factor structure of the 9-item Academic Expectations Stress Inventory (AESI) using confirmatory factor analysis on a sample of 289 Canadian adolescents and 310 Singaporean adolescents. Examination of measurement invariance tests the assumption that the model underlying a set of scores is directly comparable across groups. This study also examined the cross-cultural validity of the AESI using multigroup confirmatory factor analysis across both the Canadian and Singaporean adolescent samples. The results suggested cross-cultural invariance of form, factor loadings, and factor variances and covariances of the AESI across both samples. Evidence of AESI's convergent and discriminant validity was also reported. Findings from t-tests revealed that Singaporean adolescents reported a significantly higher level of academic stress arising from self expectations, other expectations, and overall academic stress, compared to Canadian adolescents. Also, a larger cross-cultural effect was associated with academic stress arising from other expectations compared with academic stress arising from self expectations.  相似文献   
997.
998.
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   
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