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   32699篇
  免费   2238篇
  国内免费   128篇
耳鼻咽喉   504篇
儿科学   930篇
妇产科学   712篇
基础医学   4636篇
口腔科学   2715篇
临床医学   2519篇
内科学   6839篇
皮肤病学   748篇
神经病学   2470篇
特种医学   736篇
外科学   3785篇
综合类   280篇
一般理论   12篇
预防医学   3856篇
眼科学   464篇
药学   2187篇
中国医学   262篇
肿瘤学   1410篇
  2023年   312篇
  2022年   688篇
  2021年   1305篇
  2020年   850篇
  2019年   1097篇
  2018年   1385篇
  2017年   942篇
  2016年   985篇
  2015年   1121篇
  2014年   1504篇
  2013年   1868篇
  2012年   2624篇
  2011年   3005篇
  2010年   1544篇
  2009年   1196篇
  2008年   1935篇
  2007年   1940篇
  2006年   1629篇
  2005年   1453篇
  2004年   1253篇
  2003年   1065篇
  2002年   945篇
  2001年   650篇
  2000年   542篇
  1999年   482篇
  1998年   175篇
  1997年   125篇
  1996年   111篇
  1995年   88篇
  1994年   77篇
  1993年   71篇
  1992年   197篇
  1991年   185篇
  1990年   158篇
  1989年   167篇
  1988年   130篇
  1987年   106篇
  1986年   115篇
  1985年   111篇
  1984年   89篇
  1983年   71篇
  1982年   45篇
  1980年   40篇
  1979年   65篇
  1978年   50篇
  1976年   42篇
  1974年   42篇
  1973年   51篇
  1971年   42篇
  1969年   46篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Neorickettsia helminthoeca (NH), the agent of salmon poisoning disease or canine neorickettiosis (CN), is a bacterial endosymbiont of the nematode Nanophyetus salmincola, and infections are spreading among specific fish‐eating mammalians. This article describes the pathologic and immunohistochemical findings associated with spontaneous NH‐induced infections in dogs from Southern Brazil. The principal pathologic findings were hypertrophy of Peyer patches and lymphadenopathy with lymphocytic proliferation, chronic interstitial pneumonia, and chronic enteritis associated with positive intralesional immunoreactivity to antigens of NH within macrophages and histiocytes. Positive immunoreactivity against canine parvovirus‐2 (CPV‐2) or/and canine distemper virus was not detected in the evaluated intestinal segments or in the samples from the cerebellum and lungs, respectively, from the dogs evaluated. These findings demonstrated that NH was involved in the enteric, pulmonary, and lymphoid lesions herein described, and provide additional information to confirm the occurrence of this bacterial endosymbiont within this geographical location. It is proposed that chronic pneumonia should be considered as a pathologic manifestation of NH‐induced infections. Additionally, our results show that the occurrences of CN seem to be underdiagnosed in Southern Brazil due to the confusion with the incidence of CPV‐2.  相似文献   
4.
5.
6.
7.
8.
9.
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   
10.
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   
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