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   202696篇
  免费   12392篇
  国内免费   601篇
耳鼻咽喉   2537篇
儿科学   6384篇
妇产科学   4263篇
基础医学   28518篇
口腔科学   8958篇
临床医学   15273篇
内科学   45626篇
皮肤病学   5201篇
神经病学   17198篇
特种医学   6022篇
外国民族医学   26篇
外科学   24289篇
综合类   1472篇
现状与发展   1篇
一般理论   74篇
预防医学   20507篇
眼科学   3755篇
药学   12694篇
中国医学   855篇
肿瘤学   12036篇
  2023年   1093篇
  2022年   2241篇
  2021年   4907篇
  2020年   3184篇
  2019年   4462篇
  2018年   6051篇
  2017年   4488篇
  2016年   4384篇
  2015年   5018篇
  2014年   6865篇
  2013年   8731篇
  2012年   13540篇
  2011年   14095篇
  2010年   7229篇
  2009年   6419篇
  2008年   10933篇
  2007年   11411篇
  2006年   10529篇
  2005年   10654篇
  2004年   9953篇
  2003年   9053篇
  2002年   6912篇
  2001年   5223篇
  2000年   5191篇
  1999年   4577篇
  1998年   1736篇
  1997年   1446篇
  1996年   1408篇
  1995年   1184篇
  1994年   1173篇
  1993年   1062篇
  1992年   2745篇
  1991年   2651篇
  1990年   2400篇
  1989年   2406篇
  1988年   2159篇
  1987年   1983篇
  1986年   1873篇
  1985年   1785篇
  1984年   1304篇
  1983年   1045篇
  1982年   592篇
  1981年   532篇
  1980年   517篇
  1979年   944篇
  1978年   617篇
  1977年   495篇
  1975年   551篇
  1974年   548篇
  1973年   553篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) is a rare congenital condition. It responds well to early diagnosis and treatment, but otherwise the prognosis is poor. We present our case series of 12 patients (mean age, 2 ± 2.58 yr; age range, 2 mo–8 yr), emphasizing the diagnostic process and discussing our surgical results. The diagnosis of ALCAPA should be suspected in infants who have dilated cardiomyopathy with electrocardiographic changes that suggest ischemia, and in older children who have isolated mitral regurgitation. When clinical suspicion is high, the results of 2-dimensional echocardiography combined with color-flow Doppler studies in expert hands can establish the diagnosis, thus avoiding angiography in critically ill infants. The treatment of choice in our patients was transfer and reimplantation of the left coronary artery onto the ascending aorta. There were 2 deaths: both were infants in extremis who underwent emergency surgery. An older child with severe ventricular dysfunction was given mechanical ventricular assistance and then heart transplantation. As of this report, all 10 survivors remained well and asymptomatic.  相似文献   
42.
43.
44.
The European Journal of Health Economics - The aims of this study were to assess whether there is a conceptual overlap between the questionnaires HIT-6 and EQ-5D and to develop a mapping algorithm...  相似文献   
45.
Objective:The present study evaluates a training program for fitting different hearing protection devices (HPDs) based on personal attenuation rating (PAR) before, immediately after, and six months after training.Methods:A total of 67 workers from a public university in the city of São Paulo, Brazil, were invited to participate in the measurement of PARs for foam and silicone protectors through the 3M™ E-A-Rfit Validation System. Two evaluations were performed for each protector at each sampling date: one after reading printed material (the package instructions) and another after being trained by an audiologist. The same procedures were repeated after six months. The final sample consisted of 30 individuals. ANOVA was used for statistical analysis.Results:Larger PAR values were observed after training by the audiologist, and smaller values were observed after six months. Then, after re-training, the values increased again. There were no statistically significant differences in PAR among the HPDs tested. Even after the two training sessions, 23 to 27% of the subjects did not obtain adequate PAR values.Conclusion:These findings emphasize the need for continual worker training in the correct fit of earplug HPDs and the importance of longitudinal PAR monitoring. In addition, some workers, despite the training provided, did not adapt to the HPDs used. Therefore, it is essential that other protection methods and/or other HPD types are made available to these individuals.Key words: Hearing, noise-induced hearing loss, occupational health, personal protective equipment, hearing protection devices  相似文献   
46.
47.
Dynamic contrast-enhanced ultrasound (DCE-US) has been proposed as a powerful tool for cancer diagnosis by estimation of perfusion and dispersion parameters reflecting angiogenic vascular changes. This work was aimed at identifying which vascular features are reflected by the estimated perfusion and dispersion parameters through comparison with acoustic angiography (AA). AA is a high-resolution technique that allows quantification of vascular morphology. Three-dimensional AA and 2-D DCE-US bolus acquisitions were used to monitor the growth of fibrosarcoma tumors in nine rats. AA-derived vascular properties were analyzed along with DCE-US perfusion and dispersion to investigate the differences between tumor and control and their evolution in time. AA-derived microvascular density and DCE-US perfusion exhibited good agreement, confirmed by their spatial distributions. No vascular feature was correlated with dispersion. Yet, dispersion provided better cancer classification than perfusion. We therefore hypothesize that dispersion characterizes vessels that are smaller than those visible with AA.  相似文献   
48.
49.
50.
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