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   142560篇
  免费   12841篇
  国内免费   362篇
耳鼻咽喉   1953篇
儿科学   3776篇
妇产科学   2616篇
基础医学   19378篇
口腔科学   2940篇
临床医学   16589篇
内科学   27455篇
皮肤病学   2050篇
神经病学   12821篇
特种医学   4846篇
外国民族医学   15篇
外科学   22406篇
综合类   2257篇
一般理论   111篇
预防医学   13389篇
眼科学   3053篇
药学   10968篇
  1篇
中国医学   147篇
肿瘤学   8992篇
  2021年   2754篇
  2020年   1909篇
  2019年   2866篇
  2018年   3506篇
  2017年   2501篇
  2016年   2675篇
  2015年   3057篇
  2014年   4259篇
  2013年   5820篇
  2012年   8573篇
  2011年   9004篇
  2010年   4827篇
  2009年   4523篇
  2008年   7487篇
  2007年   7883篇
  2006年   7567篇
  2005年   7437篇
  2004年   6789篇
  2003年   6387篇
  2002年   5960篇
  2001年   3102篇
  2000年   3097篇
  1999年   2797篇
  1998年   1498篇
  1997年   1162篇
  1996年   1085篇
  1995年   1084篇
  1994年   1066篇
  1993年   975篇
  1992年   2274篇
  1991年   2167篇
  1990年   2013篇
  1989年   1953篇
  1988年   1868篇
  1987年   1860篇
  1986年   1755篇
  1985年   1734篇
  1984年   1493篇
  1983年   1336篇
  1982年   933篇
  1981年   801篇
  1980年   734篇
  1979年   1252篇
  1978年   912篇
  1977年   800篇
  1976年   740篇
  1975年   736篇
  1974年   889篇
  1973年   770篇
  1972年   744篇
排序方式: 共有10000条查询结果,搜索用时 208 毫秒
1.
2.
Serrated polyps (SPs) are precursors to one-third of colorectal cancers (CRCs), with histological subtypes: hyperplastic polyps (HPs), sessile serrated lesions (SSLs) and traditional serrated adenomas (TSAs). The incidence of early-onset CRC before the age of 50 is increasing, with limited understanding of SPs in younger cohorts. Using a large colonoscopy-based cohort, we characterized epidemiologic profiles of SP subtypes, compared to conventional adenomas, with secondary analysis on early-onset polyps. Ninety-four thousand four hundred and twenty-seven patients underwent screening colonoscopies between 2010 and 2018. Demographic, endoscopic and histopathologic characteristics of each polyp subtype were described. High-risk polyps included SSLs ≥10 mm/with dysplasia and conventional adenomas ≥10 mm/with tubulovillous/villous histology/high-grade dysplasia. We examined polyp prevalence with age and compared early- (age < 50) and late-onset polyps (age ≥ 50). Eighteen thousand one hundred and twenty-five patients had SPs (4357 SSLs, 15 415 HPs, 120 TSAs) and 26 699 had conventional adenomas. High-risk SSLs were enriched in the ascending colon (44.1% vs 2.6-35.8% for other locations; P < .003). Early- and late-onset SPs had similar subsite distribution. Early-onset conventional adenomas were more enriched in the distal colon/rectum (51.8% vs 43.4%, P < .001). Multiple conventional adenomas were more represented in late-onset groups (40.8% vs 33.8%, P < .001), with no difference in SSLs. The prevalence of conventional adenomas/high-risk conventional adenomas increased continuously with age, whereas the prevalence of SSLs/high-risk SSLs was stable from age 40 years onwards. A higher proportion of women were diagnosed with early-onset than late-onset SSLs (62.9% vs 57.6%, P = .03). Conventional adenomas, SSLs, early- and late-onset polyps have distinct epidemiology. The findings have implications for improved colonoscopy screening and surveillance and understanding the etiologic heterogeneity of CRC.  相似文献   
3.
4.
5.
6.
Isolated patellofemoral arthritis is an increasingly recognized entity, and is usually associated with previous patellofemoral dysplasia or instability. Patellofemoral arthroplasty (PFA) has evolved significantly in recent years, both in terms of implant design and importantly in the understanding of appropriate patient selection. This review outlines the indications and investigations for PFA, provides a brief history of the development of contemporary implants, and presents the clinical outcomes for the prostheses most commonly used in the UK. In addition, it provides a detailed surgical technique for implantation of an onlay implant, with tips on how to optimize patellofemoral biomechanics and thus achieve a consistently good outcome.  相似文献   
7.
8.
Background The B-MaP-C study aimed to determine alterations to breast cancer (BC) management during the peak transmission period of the UK COVID-19 pandemic and the potential impact of these treatment decisions.Methods This was a national cohort study of patients with early BC undergoing multidisciplinary team (MDT)-guided treatment recommendations during the pandemic, designated ‘standard’ or ‘COVID-altered’, in the preoperative, operative and post-operative setting.Findings Of 3776 patients (from 64 UK units) in the study, 2246 (59%) had ‘COVID-altered’ management. ‘Bridging’ endocrine therapy was used (n = 951) where theatre capacity was reduced. There was increasing access to COVID-19 low-risk theatres during the study period (59%). In line with national guidance, immediate breast reconstruction was avoided (n = 299). Where adjuvant chemotherapy was omitted (n = 81), the median benefit was only 3% (IQR 2–9%) using ‘NHS Predict’. There was the rapid adoption of new evidence-based hypofractionated radiotherapy (n = 781, from 46 units). Only 14 patients (1%) tested positive for SARS-CoV-2 during their treatment journey.Conclusions The majority of ‘COVID-altered’ management decisions were largely in line with pre-COVID evidence-based guidelines, implying that breast cancer survival outcomes are unlikely to be negatively impacted by the pandemic. However, in this study, the potential impact of delays to BC presentation or diagnosis remains unknown.Subject terms: Breast cancer, Surgical oncology, Health care economics, Quality of life, Health policy  相似文献   
9.
10.
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