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   1291923篇
  免费   101228篇
  国内免费   2007篇
耳鼻咽喉   18500篇
儿科学   44846篇
妇产科学   35463篇
基础医学   184452篇
口腔科学   33837篇
临床医学   113388篇
内科学   261035篇
皮肤病学   28385篇
神经病学   101918篇
特种医学   51710篇
外国民族医学   660篇
外科学   198172篇
综合类   27469篇
现状与发展   1篇
一般理论   392篇
预防医学   97071篇
眼科学   28101篇
药学   95792篇
  2篇
中国医学   2434篇
肿瘤学   71530篇
  2018年   13443篇
  2017年   10199篇
  2016年   11130篇
  2015年   12623篇
  2014年   17530篇
  2013年   26758篇
  2012年   36770篇
  2011年   38788篇
  2010年   23227篇
  2009年   22211篇
  2008年   37358篇
  2007年   39967篇
  2006年   40215篇
  2005年   39098篇
  2004年   38264篇
  2003年   37098篇
  2002年   36347篇
  2001年   64448篇
  2000年   66960篇
  1999年   56823篇
  1998年   15305篇
  1997年   13890篇
  1996年   14347篇
  1995年   13588篇
  1994年   12898篇
  1993年   11925篇
  1992年   44873篇
  1991年   43752篇
  1990年   42502篇
  1989年   40378篇
  1988年   37160篇
  1987年   36513篇
  1986年   33875篇
  1985年   32548篇
  1984年   24350篇
  1983年   20461篇
  1982年   11845篇
  1981年   10817篇
  1980年   9610篇
  1979年   21520篇
  1978年   14962篇
  1977年   12641篇
  1976年   11773篇
  1975年   12704篇
  1974年   14792篇
  1973年   14234篇
  1972年   13044篇
  1971年   11834篇
  1970年   11124篇
  1969年   10095篇
排序方式: 共有10000条查询结果,搜索用时 31 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