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   17344篇
  免费   945篇
  国内免费   413篇
耳鼻咽喉   180篇
儿科学   264篇
妇产科学   163篇
基础医学   763篇
口腔科学   193篇
临床医学   1911篇
内科学   2885篇
皮肤病学   87篇
神经病学   455篇
特种医学   1011篇
外科学   4580篇
综合类   2964篇
预防医学   898篇
眼科学   34篇
药学   1456篇
  17篇
中国医学   270篇
肿瘤学   571篇
  2024年   20篇
  2023年   333篇
  2022年   704篇
  2021年   762篇
  2020年   785篇
  2019年   649篇
  2018年   662篇
  2017年   602篇
  2016年   738篇
  2015年   771篇
  2014年   1630篇
  2013年   1354篇
  2012年   1282篇
  2011年   1314篇
  2010年   963篇
  2009年   899篇
  2008年   894篇
  2007年   849篇
  2006年   638篇
  2005年   534篇
  2004年   434篇
  2003年   313篇
  2002年   209篇
  2001年   186篇
  2000年   172篇
  1999年   129篇
  1998年   115篇
  1997年   128篇
  1996年   82篇
  1995年   75篇
  1994年   75篇
  1993年   64篇
  1992年   42篇
  1991年   46篇
  1990年   37篇
  1989年   27篇
  1988年   28篇
  1987年   27篇
  1986年   17篇
  1985年   21篇
  1984年   15篇
  1983年   11篇
  1982年   23篇
  1981年   7篇
  1980年   13篇
  1979年   5篇
  1978年   3篇
  1977年   7篇
  1972年   2篇
  1971年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Introduction and objectivesAlthough automatic artificial intelligence (AI) coronary angiography (CAG) segmentation is arguably the first step toward future clinical application, it is underexplored. We aimed to (1) develop AI models for CAG segmentation and (2) assess the results using similarity scores and a set of criteria defined by expert physicians.MethodsPatients undergoing CAG were randomly selected in a retrospective study at a single center. Per incidence, an ideal frame was segmented, forming a baseline human dataset (BH), used for training a baseline AI model (BAI). Enhanced human segmentation (EH) was created by combining the best of both. An enhanced AI model (EAI) was trained using the EH. Results were assessed by experts using 11 weighted criteria, combined into a Global Segmentation Score (GSS: 0–100 points). Generalized Dice Score (GDS) and Dice Similarity Coefficient (DSC) were also used for AI models assessment.Results1664 processed images were generated. GSS for BH, EH, BAI and EAI were 96.9+/-5.7; 98.9+/-3.1; 86.1+/-10.1 and 90+/-7.6, respectively (95% confidence interval, p<0.001 for both paired and global differences). The GDS for the BAI and EAI was 0.9234±0.0361 and 0.9348±0.0284, respectively. The DSC for the coronary tree was 0.8904±0.0464 and 0.9134±0.0410 for the BAI and EAI, respectively. The EAI outperformed the BAI in all coronary segmentation tasks, but performed less well in some catheter segmentation tasks.ConclusionsWe successfully developed AI models capable of CAG segmentation, with good performance as assessed by all scores.  相似文献   
22.
23.
24.
《Dental materials》2022,38(2):242-250
ObjectiveTo study the mechanical behavior of endodontically-treated teeth with minimally invasive endodontic access cavities and resin composite restorations under different bonding conditions using finite element analysis (FEA).MethodsFour Class-II endodontic access cavities including the mesio-occlusal minimally-invasive (MO-MIE), mesio-occlusal conventional (MO-CONV), disto-occlusal minimally-invasive (DO-MIE), and disto-occlusal conventional (DO-CONV) cavities were prepared in 3D-printed maxillary first molars. Each tooth was subjected to root canal preparation and scanned using micro-CT to provide a 3D structural model which was virtually restored with resin composite. An intact 3D-printed molar was used as control. FEA was conducted under a 250-N vertical load. Three different interfacial bonding conditions between dentin/enamel and resin composite were considered, i.e. fully bonded, partially debonded, and fully debonded. The maximum principal stress of dentin and the normal tensile stress at the interfaces were recorded. The risk factor of failure for each component was then calculated.ResultsIn the fully-bonded tooth, the dentin-composite interface showed significantly higher stress and a higher risk factor than dentin, indicating that debonding at the dentin-composite interface would occur prior to dentin fracture. With the dentin-composite interface debonded, the enamel-composite interface exhibited higher stress and a higher risk factor than dentin, indicating that debonding at the enamel-composite interface would occur next, also prior to dentin fracture. With the resin composite fully debonded from the tooth, stress in dentin increased significantly. Irrespective of the bonding status, the CONV groups exhibited higher median stresses in dentin than the MIE groups.SignificanceWithin the limitation of this study, it was shown that debonding of the resin composite restoration increased the stress in dentin and hence the risk of dentin fracture in endodontically-restored teeth. Minimally-invasive access cavities could better safeguard the fracture resistance of interproximally-restored teeth compared to conventional ones.  相似文献   
25.
26.
27.
《Vaccine》2022,40(12):1872-1878
BackgroundThe MenB-FHbp vaccine (Trumenba®) is licensed in various countries for the prevention of meningococcal serogroup B disease in individuals ≥ 10 years of age. The clinical development program included 11 completed trials where, in each trial, MenB-FHbp had an acceptable safety profile after a primary vaccination series was administered to individuals 10–65 years of age. However, the detection of potential rare events was limited because of individual clinical trial size. The current safety analysis evaluates pooled reactogenicity and other adverse events (AEs) reported in these trials to identify new safety signals not detectable in individual trials.MethodsEleven trials contributed safety data, of which 10 recorded local and systemic reactogenicity events; 8 of the trials were controlled, and reactogenicity data were pooled for 7 of these 8 trials. Additional AE evaluations included immediate AEs (IAEs), medically attended AEs (MAEs), serious AEs (SAEs), newly diagnosed chronic medical conditions (NDCMCs), and autoimmune or neuroinflammatory conditions.ResultsLocal and systemic reactions were more frequent in the MenB-FHbp group (n = 15,294) compared with controls (n = 5509), although most reactions were transient and mild to moderate in severity. Frequencies of IAEs, SAEs, MAEs, NDCMCs, and autoimmune or neuroinflammatory conditions were similar between the MenB-FHbp and control groups.ConclusionsMenB-FHbp demonstrated a favorable safety and tolerability profile in the clinical development program of > 15,000 vaccine recipients ≥ 10 years of age. No new safety signals were identified in the pooled analysis compared with data from the individual trials. Continued postmarketing safety surveillance is important for the identification of rare events.Clinicaltrials.gov: NCT01299480; NCT000808028; NCT00879814; NCT00780806; NCT01352845; NCT01352793; NCT01461993; NCT01323270; NCT01830855; NCT01461980; NCT01768117.  相似文献   
28.
Advanced robotic technology makes it easier to perform total mesorectal excision procedures in the narrow pelvis for rectal cancer while maintaining the advantages of minimally invasive surgery. Robotic surgery for rectal cancer leads to lower conversion rates and faster recovery of urogenital function than conventional laparoscopic surgery. However, longer operative time and high cost are major weaknesses of robotic surgery. To date, most other short-term surgical outcomes, pathologic outcomes, and long-term oncologic outcomes of robotic surgery have not shown significant advantages over laparoscopic surgery. However, robotic surgery is still a valid and highly anticipated surgical approach for rectal cancer because it greatly reduces the surgeon's workload and learning curve. There are also advantages when robotic techniques are applied to technically demanding procedures such as lateral pelvic lymph node dissection or intersphincteric resection. The introduction of new surgical robot systems, including the da Vinci® SP system, is expected to expand the applications of robotic surgery and provide new advantages.  相似文献   
29.
30.
With increasing morbidity and mortality from chronic liver disease and acute liver failure, the need for liver transplantation is on the rise. Most of these patients are extremely vulnerable to infections as they are immune-compromised and have other chronic co-morbid conditions. Despite the recent advances in practice and improvement in diagnostic surveillance and treatment modalities, a major portion of these patients continue to be affected by post-transplant infections. Of these, fungal infections are particularly notorious given their vague and insidious onset and are very challenging to diagnose. This mini-review aims to discuss the incidence of fungal infections following liver transplantation, the different fungi involved, the risk factors, which predispose these patients to such infections, associated diagnostic challenges, and the role of prophylaxis. The population at risk is increasingly old and frail, suffering from various other co-morbid conditions, and needs special attention. To improve care and to decrease the burden of such infections, we need to identify the at-risk population with more robust clinical and diagnostic parameters. A more robust global consensus and stringent guidelines are needed to fight against resistant microbes and maintain the longevity of current antimicrobial therapies.  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