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   2774163篇
  免费   191614篇
  国内免费   7610篇
耳鼻咽喉   35645篇
儿科学   92249篇
妇产科学   74986篇
基础医学   384125篇
口腔科学   71859篇
临床医学   248192篇
内科学   549410篇
皮肤病学   63438篇
神经病学   230944篇
特种医学   109144篇
外国民族医学   742篇
外科学   418115篇
综合类   53159篇
现状与发展   5篇
一般理论   997篇
预防医学   214088篇
眼科学   60126篇
药学   198782篇
  8篇
中国医学   5993篇
肿瘤学   161380篇
  2021年   20258篇
  2019年   20931篇
  2018年   49731篇
  2017年   38817篇
  2016年   45187篇
  2015年   30770篇
  2014年   41651篇
  2013年   61990篇
  2012年   87787篇
  2011年   105131篇
  2010年   68804篇
  2009年   60615篇
  2008年   98901篇
  2007年   106747篇
  2006年   87588篇
  2005年   85678篇
  2004年   84140篇
  2003年   82692篇
  2002年   77917篇
  2001年   128973篇
  2000年   132089篇
  1999年   110911篇
  1998年   31814篇
  1997年   28499篇
  1996年   28593篇
  1995年   27762篇
  1994年   25480篇
  1993年   23772篇
  1992年   85421篇
  1991年   81886篇
  1990年   79078篇
  1989年   76284篇
  1988年   69676篇
  1987年   68189篇
  1986年   63751篇
  1985年   60744篇
  1984年   45216篇
  1983年   38195篇
  1982年   22809篇
  1981年   20227篇
  1979年   39182篇
  1978年   27658篇
  1977年   23422篇
  1976年   21649篇
  1975年   22922篇
  1974年   26918篇
  1973年   25454篇
  1972年   23818篇
  1971年   22003篇
  1970年   20259篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
We report on a child with several café au lait spots in association with a lumbar lipomeningomyelocele as an apparently new association. Cutaneous markers, the identification of which plays a crucial role in the early diagnosis and management of spinal malformations, can accompany occult spinal dysraphism. Herein we report a case of lumbar lipomeningomyelocele associated with an overlying café au lait spot that served as a marker of occult spinal dysraphism. The patient also had segmental café au lait spots on the face, making the association unique.  相似文献   
72.
73.
Magnetic field generated by neuronal activity could alter magnetic resonance imaging (MRI) signals but detection of such signal is under debate. Previous researches proposed that magnitude signal change is below current detectable level, but phase signal change (PSC) may be measurable with current MRI systems. Optimal imaging parameters like echo time, voxel size and external field direction, could increase the probability of detection of this small signal change. We simulate a voxel of cortical column to determine effect of such parameters on PSC signal. We extended a laminar network model for somatosensory cortex to find neuronal current in each segment of pyramidal neurons (PN). 60,000 PNs of simulated network were positioned randomly in a voxel. Biot–savart law applied to calculate neuronal magnetic field and additional phase. The procedure repeated for eleven neuronal arrangements in the voxel. PSC signal variation with the echo time and voxel size was assessed. The simulated results show that PSC signal increases with echo time, especially 100/80 ms after stimulus for gradient echo/spin echo sequence. It can be up to 0.1 mrad for echo time = 175 ms and voxel size = 1.48 × 1.48 × 2.18 mm3. With echo time less than 25 ms after stimulus, it was just acquired effects of physiological noise on PSC signal. The absolute value of the signal increased with decrease of voxel size, but its components had complex variation. External field orthogonal to local surface of cortex maximizes the signal. Expected PSC signal for tactile detection in the somatosensory cortex increase with echo time and have no oscillation.  相似文献   
74.
75.
76.
Pediatric trachyonychia is an acquired nail disease that can cause distress to families. It is a poorly understood disease, and long‐term follow‐up data are lacking. We present an institutional review of 11 children with isolated pediatric trachyonychia followed over time. Children with the diagnosis of pediatric trachyonychia were identified and invited to participate. Pictures were taken on follow‐up and a questionnaire was answered. Exclusion criteria include having another diagnosis at the initial visit that causes nail dystrophy. Eleven patients with the diagnosis of pediatric trachyonychia were available for follow‐up. The mean age of appearance was 2.7 years (range 2–7 yrs) and the average follow‐up was 66 months (range 10–126 mos). Nine patients were treated with potent topical corticosteroids, one used only petrolatum, and one took vitamin supplements. One patient was found to have an additional skin and hair diagnosis of alopecia areata on follow‐up. On follow‐up, 82% noted improvement of the nails, whereas 18% noted no change. A majority of cases of pediatric trachyonychia are isolated and improve with time, regardless of treatment.  相似文献   
77.
Sinus venosus atrial septal defect (SV‐ASD) usually coexists with partial anomalous pulmonary vein connection (PAPVC). It is a difficult diagnosis in transthoracic echocardiography (TTE) due to eccentric position of defects. We present a rare case of atypical anatomical variation in PAPVC, which was never described before. Two right pulmonary veins drained into superior vena cava, which overrode SV‐ASD and interatrial septum, a third pulmonary vein into the right atrium. Complete diagnosis could not be set after TTE, nor transesophageal echocardiography, whereas angio‐CT was finally conclusive. This diagnostic approach allowed the surgical planning.  相似文献   
78.
79.
80.
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