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   1861篇
  免费   105篇
  国内免费   13篇
耳鼻咽喉   12篇
儿科学   56篇
妇产科学   43篇
基础医学   247篇
口腔科学   29篇
临床医学   224篇
内科学   497篇
皮肤病学   28篇
神经病学   189篇
特种医学   58篇
外科学   147篇
综合类   6篇
预防医学   146篇
眼科学   36篇
药学   123篇
肿瘤学   138篇
  2024年   2篇
  2023年   23篇
  2022年   43篇
  2021年   76篇
  2020年   54篇
  2019年   63篇
  2018年   61篇
  2017年   50篇
  2016年   52篇
  2015年   67篇
  2014年   90篇
  2013年   105篇
  2012年   160篇
  2011年   138篇
  2010年   95篇
  2009年   92篇
  2008年   136篇
  2007年   128篇
  2006年   121篇
  2005年   99篇
  2004年   101篇
  2003年   76篇
  2002年   69篇
  2001年   13篇
  2000年   5篇
  1999年   10篇
  1998年   14篇
  1997年   7篇
  1996年   7篇
  1995年   8篇
  1994年   4篇
  1993年   1篇
  1992年   4篇
  1984年   1篇
  1983年   1篇
  1978年   1篇
  1975年   1篇
  1973年   1篇
排序方式: 共有1979条查询结果,搜索用时 15 毫秒
41.
BACKGROUND: Treatment of patients with suspected deep vein thrombosis (DVT) or pulmonary embolism (PE) is problematic if diagnostic imaging is not immediately available. Pretest clinical probability (PCP) and D-dimer assessment can be used to identify patients for whom empirical protective anticoagulation is indicated. To evaluate whether PCP and D-dimer assessment, together with the use of low-molecular-weight heparins (LMWHs), allow objective appraisal of DVT and PE to be deferred for up to 72 hours, patients with suspected DVT and PE were prospectively examined. METHODS: Patients identified with a high PCP or a moderate PCP with positive D-dimer test results received a protective full-dose treatment of LMWH; the remaining patients were discharged without anticoagulant administration. However, all patients were scheduled to undergo objective tests for DVT or PE within 72 hours. Standard antithrombotic therapy was administered when deferred diagnostic tests confirmed venous thromboembolism. RESULTS: In total, 409 consecutive patients with suspected DVT and 124 with suspected PE were included in this study. A total of 23.8% (95% confidence interval [CI], 20.3%-27.3%) of patients had confirmed venous thromboembolism. At the short-term follow-up (72 hours), only a single thromboembolic event (0.2%; upper 95% CI, 0.6%) had occurred, whereas at the 3-month follow-up, 5 events (1.2%; 95% CI, 0.2%-2.1%) had occurred in patients in whom diagnosis of DVT or PE had previously been ruled out. None of the patients had major bleeding events. Ninety percent of patients were treated as outpatients. CONCLUSION: Our study demonstrates that this approach allows the safe deferral of diagnostic procedures for DVT and PE for up to 72 hours.  相似文献   
42.
Prevalence of Barrett's esophagus in asymptomatic individuals   总被引:22,自引:0,他引:22  
BACKGROUND & AIMS: The incidence of esophageal adenocarcinoma in the western world has been linked to chronic heartburn, regurgitation, and the development of the premalignant epithelium of Barrett's esophagus (BE). However, up to 40% of esophageal adenocarcinomas occur in patients without prior reflux symptoms. We prospectively screened for the presence of BE in asymptomatic subjects older than 50 years of age undergoing screening sigmoidoscopy for colorectal cancer. METHODS: Subjects undergoing sigmoidoscopy for colorectal cancer (CRC) screening were invited to undergo upper endoscopy. Exclusion criteria included symptoms of gastroesophageal reflux disease (GERD) more than once a month, use of medications for GERD, or previous endoscopy. BE was classified as long-segment BE (LSBE), short-segment BE (SSBE), and microscopic specialized intestinal metaplasia of the esophagogastric junction (SIM-EGJ). RESULTS: Of 408 potential study candidates, 110 subjects were screened; 9 were women. The mean (+/-SD) age was 61 +/- 9.3 (range, 50-80) years, most of them (73%) Caucasian. Intestinal metaplasia (IM) extending above the EGJ was detected in 27 (25%) subjects; 8 (7%) had LSBE, and 19 (17%) had SSBE. Patients with BE were no more likely to be obese, consumers of tobacco or alcohol, report a family history of GERD, show association with toxic exposure, or use antacids more than once a month, compared with those without BE. CONCLUSIONS: BE was detected in 25% of asymptomatic male veterans older than 50 years of age undergoing screening sigmoidoscopy for CRC.  相似文献   
43.
44.
The aim of the current study was to investigate the contribution of various strategies to increase influenza vaccine uptake among health care workers (HCWs) working in hospitals in Greece during the 2005-2006 season. A total of 132 Greek public hospitals participated in the study. The mean HCWs vaccination rate against influenza during 2005-2006 was 16.36% compared with 1.72% during the previous season. Logistic regression analysis showed that the implementation of the following strategies was significantly associated with influenza vaccination rates above the mean vaccination rate: a mobile vaccination team (OR 2.942, 95% CI 1.154-5.382, p-value 0.016) and lectures on influenza and influenza vaccine (OR 2.386, 95% CI 0.999-5.704, p-value 0.036). In conclusion, in Greece influenza vaccination rates among HCWs remain low; however, the implementation of specific strategies was associated with increased vaccine uptakes.  相似文献   
45.
Objectives. We sought to evaluate the opinions of medical students and graduates regarding the quality of medical education in Greece. Methods. Two online questionnaires concerning the undergraduate medical education and specialty training respectively were distributed. Results. Regarding the quality of undergraduate medical education, 52.1% of participants replied favorably while clinical training was found satisfactory by 45.1. Dissatisfaction rates with research opportunities and support from tutors reached 88.4 and 83.3%, respectively. The majority (75.3%) supported the introduction of examinations for commencing specialty training. 52.3% of physicians were satisfied with the quality of specialty training. The most common complaint was the absence of a formal educational program. 67.2% of participants were dissatisfied with working conditions during their specialty training, with 70.1% working >60 h per week. Physicians practicing medical specialties were more satisfied with the quality of specialty training than those practicing surgical specialties (odds ratio: 1.43; 95% confidence limits: 1.09–1.87) and were less likely to work for >60 h per week (odds ratio: 0.66; 95% confidence limits: 0.48–0.9). Conclusion. Opinions expressed in this survey highlight the need for reforming medical education in Greece.  相似文献   
46.
47.
AIM: To study the association of the frequency and pattern of KIT and PDGFRA mutations and clinicopathological factors in a group of patients with gastrointestinal stromal tumors (GIST). METHODS: Thirty patients with GIST were examined. Exons 9, 11, 13, and 17 of the KIT and exons 12 and 18 of the PDGFRA gene were analyzed for the presence of mutations by PCR amplification and direct sequencing. RESULTS: KIT or PDGFRA mutations were detected in 21 of the 30 patients (70%). Sixteen patients had mutations within KIT exon 11, three within KIT exon 9, and two within PDGFRA exon 18. GISTs with KIT exon 9 mutations were predominantly located in the small intestine, showed a spindle cell phenotype, and were assessed as potentially malignant. GISTs with KIT exon 11 mutations were located in the stomach and intestine, showed mainly a spindle cell phenotype, and were scored as potentially malignant (P 〈 0.05). Tumors with KIT exon 11 codon 557/558 deletion/insertion mutations were found to be associated with a potentially malignant clinical behaviour (P 〈 0.003). GISTs with PDGFRA mutations located in stomach showed a mixed cell phenotype and were classified as of very low or low moderate malignant potential. CONCLUSION: Determination of KIT and PDGFRA mutations should be additional parameters for the better prediction of GISTs clinical behaviour. Tumors with deletion/insertion mutations affecting codons 557/558 of the KIT gene seem to represent a distinct subset of malignant GISTs.  相似文献   
48.
Iron overload may predominantly involve parenchymal or reticuloendothelial cells, the prototype of parenchymal iron overload being HFE-related genetic haemochromatosis. We studied a family with autosomal dominant hyperferritinaemia in whom the proband showed selective iron accumulation in the Kupffer cells on liver biopsy. Analysis of L and H ferritin genes excluded mutations responsible for hereditary hyperferritinaemia/cataract syndrome or similar translational disorders. Sequence analysis of the ferroportin gene (SLC11A3) in four individuals with hyperferritinaemia singled out a three base pair deletion in a region that contains four TTG repeats. This mutation removes a TTG unit from 780 to 791, and predicts the loss of one of three sequential valine residues 160-162. Denaturing high performance liquid chromatography can be used for its detection. SLC11A3 polymorphism analysis indicates that this probably represents a recurrent mutation due to slippage mispairing. Affected individuals may show marginally low serum iron and transferrin saturation, and young women may have marginally low haemoglobin concentration levels. Serum ferritin levels are directly related to age, but are 10-20 times higher than normal. Heterozygosity for the ferroportin Val 162 deletion represents the prototype of selective reticuloendothelial iron overload, and should be taken into account in the differential diagnosis of hereditary or congenital hyperferritinaemias.  相似文献   
49.
50.
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