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   2595786篇
  免费   185591篇
  国内免费   7587篇
耳鼻咽喉   34347篇
儿科学   85445篇
妇产科学   71827篇
基础医学   364699篇
口腔科学   69917篇
临床医学   235899篇
内科学   516909篇
皮肤病学   62575篇
神经病学   214196篇
特种医学   100050篇
外国民族医学   736篇
外科学   387157篇
综合类   50497篇
现状与发展   5篇
一般理论   975篇
预防医学   197409篇
眼科学   56790篇
药学   188513篇
  9篇
中国医学   5341篇
肿瘤学   145668篇
  2021年   20174篇
  2019年   20813篇
  2018年   29532篇
  2017年   22748篇
  2016年   26419篇
  2015年   29715篇
  2014年   40752篇
  2013年   60876篇
  2012年   80844篇
  2011年   85161篇
  2010年   51396篇
  2009年   49511篇
  2008年   79612篇
  2007年   84455篇
  2006年   86134篇
  2005年   82255篇
  2004年   79203篇
  2003年   76474篇
  2002年   73765篇
  2001年   128477篇
  2000年   131399篇
  1999年   110603篇
  1998年   31334篇
  1997年   27989篇
  1996年   28270篇
  1995年   27431篇
  1994年   25111篇
  1993年   23467篇
  1992年   85208篇
  1991年   81602篇
  1990年   78812篇
  1989年   76091篇
  1988年   69499篇
  1987年   68019篇
  1986年   63556篇
  1985年   60540篇
  1984年   44965篇
  1983年   37966篇
  1982年   22476篇
  1981年   20009篇
  1979年   38986篇
  1978年   27454篇
  1977年   23260篇
  1976年   21500篇
  1975年   22818篇
  1974年   26790篇
  1973年   25374篇
  1972年   23757篇
  1971年   21958篇
  1970年   20192篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Southgate  M. Therese 《JAMA》2006,296(13):1564
  相似文献   
92.
Volume and profile of alcohol consumption among students and classmates as predictors of aggression and victimization: a multilevel analysis among Swiss adolescents

Objective:  

To test the effects of the volume of alcohol consumption and drinking patterns on alcohol-related aggression and victimization, both at the individual and class levels.  相似文献   
93.
94.
95.
There are no data available combining transbronchial needle aspiration (TBNA) of mediastinal lymph nodes and positron emission tomography (PET) in the staging of nonsmall cell lung cancer (NSCLC). The aim of the current study was to determine if these two methods can enhance the negative predictive value of the individual modality alone, for a specific lymph node station, and if this integrated approach can reduce the number of mediastinoscopies. A total of 113 patients with enlarged mediastinal lymph nodes (> or = 1 cm), who underwent both TBNA and PET scanning, were included. In 51 patients, histopathology, confirmed by surgical lymph node dissection, was compared with PET results and TBNA. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy to detect malignant lymphadenopathy was 68 (13/19), 89 (119/134), 46 (13/28), 95 (119/125) and 86% (132/152) for PET, respectively; 54% (6/11), 100 (53/53), 100 (6/6), 91 (53/58) and 92% (59/64), respectively for TBNA; and 100 (11/11), 94 (50/53), 79 (11/14), 100 (50/50) and 95 (61/64) for combined TBNA and PET, respectively. Combination of transbronchial needle aspiration and positron emission tomography has the potential to allow adequate mediastinal staging of nonsmall cell lung cancer with enlarged lymph nodes in most patients without the need for mediastinoscopy.  相似文献   
96.
97.
98.
Effect of catalase supplementation in storage media for avulsed teeth   总被引:1,自引:0,他引:1  
Abstract – The type of liquid medium used to store avulsed teeth prior to replantation has been shown to affect the long‐term prognosis. One possibility is that some storage media contain hydrogen peroxide (H2O2) that may be toxic to periodontal ligament cells. Therefore, the aim of this study was to determine if the addition of catalase to storage media improved the prognosis of replanted dog teeth. Forty‐eight mongrel premolar roots were endodontically treated, extracted, randomly divided and placed into one of four storage media: Hank's balanced salt solution (HBSS), containing no antioxidant); Viaspan, containing the antioxidant, glutathione, or the same two media supplemented with catalase(100 U ml?1) for 1, 5, or 26 h prior to replantation. After 2 months, the dogs were euthanized and the roots histologically examined to evaluate the attachment tissues. Regardless of the storage medium used, overall healing was excellent and only 4% of the roots displayed inflammatory or replacement resorption. When roots from the different storage media were compared, those stored in HBSS were found to display the highest incidence of surface resorption (55.7%). Supplementation of HBSS with catalase resulted in a lower level of surface resorption (48.6%) that was statistically significant (P < 0.05). Roots stored in Viaspan – or + catalase displayed even lower levels of surface resorption (41.3 and 38.2%, respectively). The improvement observed with catalase‐supplemented HBSS was confined to the 45‐min incubation period; only Viaspan – or + catalase reduced surface resorption at the 5‐ and 26‐h incubations. Collectively, these data demonstrate that roots stored in media containing antioxidant activity undergo less surface resorption. These results suggest that low levels of H2O2 in storage media for avulsed teeth may adversely affect periodontal ligament cells.  相似文献   
99.
100.
Clinicopathological and electron microscopical findings of eight cases of enzootic nasal adenocarcinoma of sheep, diagnosed solely in one big flock in Slovenia between years 2001 and 2003 are described. All affected sheep were female, their mean age was 4.5 ± 1.5 years and they either belonged to the Istrian pramenka breed (five sheep) or were crossbreeds (three sheep). Tumours that arose from the ethmoid area of the nasal cavity were unilateral in six cases (75%) and bilateral in two cases (25%). All tumours were classified as adenocarcinomas by histopathological examination and they displayed either a combination of tubular and papillary growth or less often solely tubular proliferation. No metastases were detected in regional lymph nodes, brain or other organs. Electron microscopical studies performed on the reprocessed paraffin‐embedded tissues revealed the presence of the virus‐like particles with an average diameter between 70 and 90 nm.  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