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   21174篇
  免费   1959篇
  国内免费   62篇
耳鼻咽喉   199篇
儿科学   674篇
妇产科学   771篇
基础医学   2660篇
口腔科学   205篇
临床医学   3545篇
内科学   4097篇
皮肤病学   299篇
神经病学   2250篇
特种医学   418篇
外科学   2104篇
综合类   142篇
一般理论   22篇
预防医学   2776篇
眼科学   327篇
药学   1210篇
中国医学   16篇
肿瘤学   1480篇
  2024年   51篇
  2023年   453篇
  2022年   610篇
  2021年   1244篇
  2020年   795篇
  2019年   1017篇
  2018年   1157篇
  2017年   819篇
  2016年   858篇
  2015年   914篇
  2014年   1163篇
  2013年   1391篇
  2012年   1911篇
  2011年   1919篇
  2010年   969篇
  2009年   917篇
  2008年   1253篇
  2007年   1068篇
  2006年   928篇
  2005年   753篇
  2004年   615篇
  2003年   526篇
  2002年   439篇
  2001年   102篇
  2000年   93篇
  1999年   102篇
  1998年   121篇
  1997年   105篇
  1996年   73篇
  1995年   79篇
  1994年   62篇
  1993年   38篇
  1992年   58篇
  1991年   44篇
  1990年   52篇
  1989年   45篇
  1988年   33篇
  1987年   26篇
  1986年   43篇
  1985年   30篇
  1984年   31篇
  1983年   28篇
  1982年   29篇
  1981年   18篇
  1980年   19篇
  1979年   18篇
  1978年   15篇
  1977年   32篇
  1976年   24篇
  1973年   17篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
22.
23.
BACKGROUND: The dopamine transporter (DAT) is known to be a key regulator of dopamine, and recent studies of genetics, treatment, and imaging have highlighted the role of DAT in attention-deficit/hyperactivity disorder (ADHD). The findings of in vivo neuroimaging of DAT in ADHD have been somewhat discrepant, however. METHOD: Dopamine transporter binding was measured using a highly selective ligand (C-11 altropane) and positron emission tomography (PET). The sample consisted of 47 well-characterized, treatment-na?ve, nonsmoking, non-comorbid adults with and without ADHD. Additionally, control subjects had few symptoms of ADHD. RESULTS: Results showed significantly increased DAT binding in the right caudate in adults with ADHD compared with matched control subjects without this disorder. CONCLUSIONS: These results confirm abnormal DAT binding in the striatum of adults with ADHD and provide further support that dysregulation of DAT may be an important component of the pathophysiology of ADHD.  相似文献   
24.
OBJECTIVE: The aim of this study was to determine whether EEG slowing is more pronounced in older than younger OSAS patients and to verify whether this cortical slowing is correlated to daytime performance, respiratory perturbation and sleep fragmentation. METHODS: Twelve young OSAS patients (mean age 38.2+/-2.0 y) and 13 older OSAS patients (mean age 62.2+/-1.9 y) along with 13 young controls (mean age 35.8+/-2.0 y) and 14 older controls (mean age 60.2+/-2.0 y) underwent a polysomnographic evaluation followed by a waking EEG recording. As a global index of cortical slowing, a ratio of slow-to-fast frequencies was calculated in all cortical regions. Daytime performance was assessed using the four choice reaction time test. RESULTS: Differences in waking EEG and in daytime performance were analyzed by ANOVAs with Group and Age as factors. Waking EEG did not yield a Group by Age interaction. OSAS patients had higher ratios across all regions than controls. Similarly, daytime performance revealed no Group by Age interaction. However, OSAS patients showed more lapses than controls and older subjects were slower than younger subjects. CONCLUSIONS: Our results indicate that age does not interact with OSAS to worsen the severity of cortical slowing, but age can add to the OSAS effect to worsen daytime performance deficits in OSAS patients. SIGNIFICANCE: The daytime performance deficits observed particularly in elderly OSAS patients warrant a careful clinical assessment of these patients to prevent accidents and injuries.  相似文献   
25.

Background  

There are few effective strategies reported for the primary prevention of low back pain (LBP). Core stabilization exercises targeting the deep abdominal and trunk musculature and psychosocial education programs addressing patient beliefs and coping styles represent the current best evidence for secondary prevention of low back pain. However, these programs have not been widely tested to determine if they are effective at preventing the primary onset and/or severity of LBP. The purpose of this cluster randomized clinical trial is to determine if a combined core stabilization exercise and education program is effective in preventing the onset and/or severity of LBP. The effect of the combined program will be compared to three other standard programs.  相似文献   
26.
27.
The most common cause of illness in infancy and childhood is acute infection of the respiratory tract. Several recent studies have reported that life-threatening respiratory disease in infancy, such as pneumonia and bronchiolitis, is directly related to the smoking habits of parents. The effects of smoking are more hazardous to youngsters because babies and young children breathe more rapidly than adults. Because of this higher breathing rate, they inhale more air—and more pollution—in comparison to their total body weight. The harmful effects of cigarette smoking on infants and children and recommendations for specific interventions to minimize or eliminate this health hazard are discussed.  相似文献   
28.
There is limited information regarding oral health status and other predictors of oral health‐related quality of life. An association between oral health status and perceived oral health‐related quality of life (OHQOL) might help clinicians motivate patients to prevent oral diseases and improve the outcome of some dental public health programs. This study evaluated the relationship between older persons' OHQOL and their functional dentition, caries, periodontal status, chronic diseases, and some demographic characteristics. A group of 733 low‐income elders (mean age 72.7 ISD=4.71, 55.6% women, 55.1% members of ethnic minority groups in the U.S. and Canada) enrolled in the TEETH clinical trial were interviewed and examined as part of their fifth annual visit for the trial. OHQOL was measured by the Geriatric Oral Health Assessment Index (GOHAI); oral health and occlusal status by clinical exams and the Eichner Index; and demographics via interviews. Elders who completed the four‐year assessment had an average of 21.5 teeth (SD=6.9). with 8.5 occluding pairs (SD=4.6), and 32% with occlusal contacts in all four occluding zones. Stepwise multiple regressions were conducted to predict total GOHAI and its subscores (Physical, Social, and Worry). Functional dentition was a less significant predictor than ethnicity and being foreign‐bom. These variables, together with gender, years since immigrating, number of carious roots, and periodontal status, could predict 32% of the variance in total GOHAI, 24% in Physical, 27% in Social, and 21 % in the Worry subscales. These findings suggest that functional dentition and caries influence older adults' OHQOL, but that ethnicity and immigrant status play a larger role.  相似文献   
29.
30.
The authors report the occurrence and clinical course of serous retinal detachment following glaucoma surgery in three patients. Serous detachment resolved in all patients spontaneously following treatment with oral and topical steroids.  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