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   2864147篇
  免费   197740篇
  国内免费   7906篇
耳鼻咽喉   36871篇
儿科学   94270篇
妇产科学   76352篇
基础医学   396085篇
口腔科学   73891篇
临床医学   257213篇
内科学   568237篇
皮肤病学   65597篇
神经病学   239287篇
特种医学   113097篇
外国民族医学   745篇
外科学   432424篇
综合类   54329篇
现状与发展   5篇
一般理论   1071篇
预防医学   220918篇
眼科学   61811篇
药学   204462篇
  8篇
中国医学   6140篇
肿瘤学   166980篇
  2021年   22429篇
  2019年   22927篇
  2018年   51699篇
  2017年   40280篇
  2016年   46831篇
  2015年   32998篇
  2014年   44825篇
  2013年   66252篇
  2012年   93907篇
  2011年   111582篇
  2010年   72482篇
  2009年   64203篇
  2008年   104437篇
  2007年   112419篇
  2006年   93560篇
  2005年   91646篇
  2004年   89476篇
  2003年   87451篇
  2002年   82674篇
  2001年   130125篇
  2000年   133030篇
  1999年   112084篇
  1998年   32925篇
  1997年   29359篇
  1996年   29336篇
  1995年   28427篇
  1994年   26039篇
  1993年   24276篇
  1992年   86082篇
  1991年   82483篇
  1990年   79578篇
  1989年   76801篇
  1988年   70137篇
  1987年   68638篇
  1986年   64160篇
  1985年   61150篇
  1984年   45578篇
  1983年   38531篇
  1982年   23204篇
  1981年   20606篇
  1979年   39488篇
  1978年   27966篇
  1977年   23628篇
  1976年   21925篇
  1975年   23141篇
  1974年   27209篇
  1973年   25689篇
  1972年   24026篇
  1971年   22161篇
  1970年   20431篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
82.
Acne vulgaris (acne) is a chronic inflammatory disease of the sebaceous gland, characterized by follicular hyperkeratinization, excessive colonization by Propionibacterium acnes (Pacnes) as well as immune reactions and inflammation. Despite an armamentarium of topical treatments available including benzoyl peroxide, retinoids and azelaic acid, topical antibiotics in monotherapies, especially erythromycin and clindamycin, are still used in Europe to treat acne. This intensive use led to antimicrobial‐resistant P. acnes and staphylococci strains becoming one of the main health issues worldwide. This is an update on the current topical acne treatments available in Europe, their mechanism of action, their potential to induce antimicrobial resistance and their clinical efficacy and safety.  相似文献   
83.
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   
84.
85.
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   
86.
87.
88.
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   
89.
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   
90.
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