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   31635篇
  免费   1961篇
  国内免费   131篇
耳鼻咽喉   511篇
儿科学   795篇
妇产科学   573篇
基础医学   4477篇
口腔科学   2971篇
临床医学   2490篇
内科学   6226篇
皮肤病学   856篇
神经病学   2311篇
特种医学   765篇
外科学   3371篇
综合类   129篇
一般理论   9篇
预防医学   3808篇
眼科学   462篇
药学   2238篇
中国医学   285篇
肿瘤学   1450篇
  2023年   283篇
  2022年   299篇
  2021年   1111篇
  2020年   760篇
  2019年   979篇
  2018年   1213篇
  2017年   839篇
  2016年   954篇
  2015年   1096篇
  2014年   1411篇
  2013年   1776篇
  2012年   2495篇
  2011年   2959篇
  2010年   1518篇
  2009年   1223篇
  2008年   1912篇
  2007年   2020篇
  2006年   1729篇
  2005年   1505篇
  2004年   1306篇
  2003年   1098篇
  2002年   981篇
  2001年   552篇
  2000年   496篇
  1999年   462篇
  1998年   188篇
  1997年   145篇
  1996年   116篇
  1995年   86篇
  1994年   102篇
  1993年   77篇
  1992年   198篇
  1991年   189篇
  1990年   134篇
  1989年   161篇
  1988年   127篇
  1987年   113篇
  1986年   126篇
  1985年   90篇
  1984年   90篇
  1983年   79篇
  1982年   54篇
  1980年   42篇
  1979年   70篇
  1977年   42篇
  1976年   44篇
  1971年   45篇
  1970年   39篇
  1969年   39篇
  1968年   40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.
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   
8.
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   
9.
10.
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