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   1415篇
  免费   204篇
  国内免费   57篇
儿科学   17篇
妇产科学   3篇
基础医学   37篇
临床医学   249篇
内科学   672篇
皮肤病学   1篇
神经病学   5篇
特种医学   85篇
外科学   208篇
综合类   145篇
预防医学   35篇
药学   52篇
  1篇
中国医学   10篇
肿瘤学   156篇
  2023年   61篇
  2022年   43篇
  2021年   51篇
  2020年   99篇
  2019年   94篇
  2018年   63篇
  2017年   80篇
  2016年   63篇
  2015年   73篇
  2014年   106篇
  2013年   145篇
  2012年   96篇
  2011年   62篇
  2010年   66篇
  2009年   61篇
  2008年   62篇
  2007年   75篇
  2006年   66篇
  2005年   73篇
  2004年   30篇
  2003年   21篇
  2002年   27篇
  2001年   24篇
  2000年   21篇
  1999年   13篇
  1998年   11篇
  1997年   6篇
  1996年   12篇
  1995年   3篇
  1994年   12篇
  1993年   9篇
  1992年   10篇
  1991年   6篇
  1990年   4篇
  1989年   4篇
  1988年   4篇
  1987年   5篇
  1986年   5篇
  1985年   3篇
  1983年   1篇
  1982年   2篇
  1981年   1篇
  1979年   2篇
  1978年   1篇
排序方式: 共有1676条查询结果,搜索用时 15 毫秒
31.
目的 探讨纤维结肠镜技术在腹腔镜结直肠癌切除术中的应用价值.方法 在腹腔镜结直肠癌切除术中应用结肠镜完成11例,其中5例根治切除乙状结肠癌及息肉肠段,6例根治切除直肠癌.结果 手术均获成功,无中转开腹,术后无吻合口瘘等并发症.结论 纤维结肠镜配合腹腔镜结直肠癌手术,有助于结直肠病灶及切缘的准确定位,在提高手术成功率的同时,保证肿瘤的根治性和吻合质量,弥补了腹腔镜手术的缺陷.  相似文献   
32.
Objectives: The epidemiology of lower gastrointestinal bleeding (LGIB) in Western populations has been reported; however, there are scant Asian reports. The aim of the present study was to determine the etiology of LGIB in a Chinese population by reporting a retrospective case series and a systematic analysis of Chinese literature. Methods: A large colonoscopy database in a tertiary endoscopic center was searched to identify all patients with the indication of LGIB. The data, including patients' sex, age, endoscopic and pathological findings, were collected and analyzed. A comprehensive database search of the Chinese literature was carried out to obtain all relevant studies. Results: In our series, a total of 720 patients with LGIB were included. There were 425 males and 295 females with a median age of 50 years, the most common etiologies of LGIB were inflammatory bowel disease (IBD; 30.2%), polyps (23.4%) and cancer (10.7%). In 30.2% of all the patients, no obvious causes were identified. A systematic analysis of Chinese literature found an additional 160 studies providing relevant data in 53 951 patients. Overall, colorectal cancer (24.4%), colorectal polyps (24.1%), colitis (16.8%), anorectal disease (9.8%) and IBD (9.5%) were the most common etiologies of LGIB. The main etiologies were different between adults, the elderly and children. Conclusion: The study shows colorectal cancer, colorectal polyps, colitis, anorectal disease and IBD were the most common etiologies of LGIB in the Chinese adult and elderly population, whereas colorectal polyps, chronic colitis and intussusception were the main causes of LGIB in Chinese children. Whereas diverticulum, the most common cause of LGIB in Western populations, is uncommon in China.  相似文献   
33.
34.
Cecal intubation is a critical aspect of effective, complete colonoscopy. Difficult colonoscopy is most often considered as one in which it is challenging or impossible to reach the cecum. It may be a common occurrence due to patient and/or endoscopist factors. Incomplete colonoscopies should be avoided, since patients in this context present an important prevalence of lesions that escape examination. The approach to successful cecal intubation should depend on characterization of the problem as redundant colon or difficult sigmoid colon. Most patients with a prior incomplete colonoscopy can be colonoscoped successfully, if careful attention is paid to technique, using a variety of scopes, colonoscopy methods and additional equipment. Sufficient time should be allotted to make the attempt.  相似文献   
35.
Objective. In recent years persons at risk for colorectal cancers (CRC) have been subjected to follow-up with colonoscopy in many centres. There is, however, limited knowledge about the effect of such interventions. The objective of this study was to report the results of our observations during the past 15 years. Material and methods. Healthy persons were included in the study according to their family history of CRCs, and prospectively followed with colonoscopies. Results. Altogether, 1133 individuals were included and observed for a total of 3474 follow-up years from the first to the last colonoscopy initiated by our activity. Mismatch repair (MMR) mutations were detected in 6.5% of cases. A total of 1383 polyps were removed, 72% were less than 5 mm in diameter. Findings were scored as hyperplastic polyps (n=887), adenomas with mild to moderate dysplasia (n=460), adenomas with high-grade dysplasia (n=30) and cancers (n=6). Two cancers were observed after the first colonoscopy, compared with 2.6 expected by chance and more than 20 expected under the hypothesis of predominant inherited diseases in the families. Observed annual incidence rates for adenomas were similar in all groups, while in the mutation carriers there was a higher frequency of progression to severe dysplasia or infiltrating cancer. Conclusions. A simple explanation for the combined findings may be that all selected families had a similar tendency to produce adenomas, while mutation carriers more frequently demonstrated dysplasia/cancer in the adenomas. The low annual incidence rates for CRC indicated that the removal of adenomas may have prevented cancers.  相似文献   
36.
Existing and emerging colorectal screening tests can be assessed in terms of the key categories of diagnostic performance, procedural risks, patient acceptability, and cost-effectiveness. To push a new screening test to acceptance, it need not outperform existing strategies in all of these criteria. Rather, a relative advantage in one criterion combined with acceptable performance in the others may be considered adequate. For computed tomographic colonography (CTC), a strong case can be made that this test meets or exceeds optical colonoscopy, the current screening standard, in all of these categories. Published data, including our own experience with CTC screening, will be reviewed to support this claim. Reasons why CTC has not yet achieved its full potential as a valuable screening test for colorectal cancer prevention will also be considered.  相似文献   
37.
38.
39.
40.
A method of fibre-optic colonoscopy with simultaneous high resolution MRI has been developed to obtain cross-sectional information of the intramural and extramural extent of lesions, for diagnostic and therapeutic purposes. An MR-compatible colonoscope with receiver coil was designed, developed and used in ex vivo studies to scan a section of large bowel in transverse and longitudinal planes with T1 and T2 weighted spin-echo sequences. In vivo five patients were followed-up after excision of large bowel cancer. The patients were three men and two women aged 50-77 years, (mean 65.6 years) who were studied on a 0.5 T scanner (Picker Asset, OH, USA). The coil and colonoscope were inserted into the rectum. After routine visual inspection of the colon, T1 weighted spin-echo images and radio-frequency spoiled gradient-echo images of the bowel wall were obtained. Ex vivo: three layers of bowel wall were identified: an intermediate to high signal-intense mucosa, a high signal intensity layer on T1 weighting which corresponded to the submucosa, and a low signal intensity muscularis propria. In vivo: On T1 weighted images three layers could be identified that corresponded to the layers seen on the ex vivo imaging. This pilot study demonstrates that MR colonoscopy is feasible and allows delineation of bowel wall structure, thus providing a useful adjunct to conventional colonscopy.  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