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   150164篇
  免费   11127篇
  国内免费   487篇
耳鼻咽喉   1584篇
儿科学   4338篇
妇产科学   2930篇
基础医学   20404篇
口腔科学   2612篇
临床医学   16586篇
内科学   30265篇
皮肤病学   2775篇
神经病学   15712篇
特种医学   5128篇
外国民族医学   6篇
外科学   19624篇
综合类   1627篇
现状与发展   1篇
一般理论   157篇
预防医学   14716篇
眼科学   2554篇
药学   10215篇
中国医学   170篇
肿瘤学   10374篇
  2023年   1063篇
  2022年   1881篇
  2021年   3902篇
  2020年   2394篇
  2019年   3702篇
  2018年   4265篇
  2017年   3204篇
  2016年   3631篇
  2015年   4048篇
  2014年   5506篇
  2013年   7205篇
  2012年   10994篇
  2011年   10980篇
  2010年   6306篇
  2009年   5535篇
  2008年   9289篇
  2007年   9720篇
  2006年   9024篇
  2005年   8778篇
  2004年   7983篇
  2003年   6995篇
  2002年   6679篇
  2001年   2067篇
  2000年   1913篇
  1999年   1867篇
  1998年   1511篇
  1997年   1206篇
  1996年   979篇
  1995年   969篇
  1994年   805篇
  1993年   730篇
  1992年   1216篇
  1991年   1111篇
  1990年   1057篇
  1989年   1018篇
  1988年   897篇
  1987年   834篇
  1986年   855篇
  1985年   850篇
  1984年   703篇
  1983年   614篇
  1982年   568篇
  1981年   473篇
  1980年   415篇
  1979年   524篇
  1978年   426篇
  1977年   381篇
  1975年   343篇
  1974年   359篇
  1973年   359篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
The cellular infiltrate present in human diseased gingiva was analyzed in biopsies from 12 patients with gingivitis or periodontitis. The samples studied had been obtained in the course of surgery at inflammatory sites remaining after institution of periodontal treatment. Histological and immunological techniques were used to identify macrophages, B-cells, plasma-cells, T-cells and T cell subsets, as well as cells expressing class II HLA membrane antigens. T-cells appeared as the predominant population, but plasma-cells were also visualized in nearly all samples. Both OKT4+ and OKT8+ cells were seen in all cases, the latter being more numerous in periodontitis patients. Interdigitating-like cells were observed, positively labelled for class II antigens, as well as macrophages which were more numerous in periodontitis patients. These results suggest the participation of all components of the immune response in gingival disease, in a way resembling chronic recurrent inflammatory diseases.  相似文献   
33.
34.
35.
Balanced analgesia (an opioid and a nonsteroidal anti-inflammatory agent) after hysterectomy often leads to better postoperative pain outcomes. Researchers compared post-hysterectomy patients who received balanced analgesia with those who received only morphine patient-controlled analgesia, and their relationship with pain scores, ambulation, and hospital length of stay.  相似文献   
36.
A case of esthesioneuroblastoma with an unusual clinical and radiographic presentation is reported. The presenting symptoms as well as the computed tomographic examination were compatible with a primary intracranial mass.  相似文献   
37.
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   
38.
39.
PURPOSE: Videofluorography (VF) and endoscopy are commonly used for dynamic imaging (DI) of pharyngeal swallowing but do not offer transverse plane (TP) information. The aim of the present study was to evaluate helical computerized tomography (HCT) to measure the DI capability pharyngeal swallowing in the TP. METHODS: The HCT scan technique used was a single-slice cine mode with scan times of 100 ms. All 15 subjects were studied supine during dry swallow, swallowing of barium sulphate jelly and 3, 10, 15 or 20 ml of a 40% barium sulphate solution. Nine subjects repeated the test twice at more than 1 week's interval to determine the test-retest reliability. RESULTS: Swallowing leads to closure of the vocal folds, pharyngeal constriction and narrowing of the piriform sinuses allowing jelly passage between the sinuses. Laryngeal elevation then occurs with the opening of the pharyngoesophageal segment (PES). Swallowing a bolus of 20 ml produced the maximum anteroposterior and transverse diameters as well as the maximum opening area of the PES. The test-retest intraclass correlation coefficients with liquid deglutition ranged from 0.86 to 0.98. CONCLUSIONS: This study shows that HCT enables visualization of TP of PES complementing VF or endoscopic swallowing studies.  相似文献   
40.
The objective of this study was to investigate the effect of fluoridated elastomeric ligatures on the microbiology of local dental plaque in vivo. This randomized, prospective, longitudinal, clinical trial had a split-mouth crossover design. The subjects were 30 patients at the beginning of their treatment with fixed orthodontic appliances in the orthodontic departments of the Liverpool and the Sheffield dental hospitals in the United Kingdom. The study consisted of 2 experimental periods of 6 weeks with a washout period between. Fluoridated elastomers were randomly allocated at the first visit to be placed around brackets on tooth numbers 12, 11, 33 or 22, 21, 43. Nonfluoridated elastomers were placed on the contralateral teeth. Standard nonantibacterial fluoridated toothpaste and mouthwash were supplied. After 6 weeks (visit 2), the elastomers were removed, placed in transport media, and plated on agar within 2 hours. Nonfluoridated elastomers were placed on all brackets for 1 visit to allow for a washout period. At visit 3, fluoridated elastomers were placed on the teeth contralateral to those that received them at visit 1. At visit 4, the procedures at visit 2 were repeated. Samples were collected on visits 2 and 4. A logistic regression was performed, with the presence or absence of streptococcal or anaerobic growth as the dependent variable. A mixed-effects analysis of variance was carried out with the percentage of streptococcal or anaerobic bacterial count as the dependent variable. The only significant independent variables were the subject variable (P =<.001) for the percentage of streptococcal and anaerobic bacterial count and the visit variable for the percentage of streptococcal count (P =<.001). The use of fluoridated or nonfluoridated elastomers was not significant for percentage of either streptococcal (P =.288) or anaerobic count (P =.230). Fluoridated elastomers are not effective at reducing local streptococcal or anaerobic bacterial growth after a clinically relevant time in the mouth.  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