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   1103814篇
  免费   85583篇
  国内免费   10141篇
耳鼻咽喉   13911篇
儿科学   35798篇
妇产科学   30575篇
基础医学   157254篇
口腔科学   29594篇
临床医学   103161篇
内科学   209086篇
皮肤病学   24164篇
神经病学   84732篇
特种医学   42380篇
外国民族医学   375篇
外科学   160893篇
综合类   42071篇
一般理论   390篇
预防医学   84110篇
眼科学   26009篇
药学   83588篇
  79篇
中国医学   7930篇
肿瘤学   63438篇
  2021年   9855篇
  2019年   10560篇
  2018年   13653篇
  2017年   11657篇
  2016年   12192篇
  2015年   15269篇
  2014年   20623篇
  2013年   27755篇
  2012年   37424篇
  2011年   40071篇
  2010年   24244篇
  2009年   21977篇
  2008年   35040篇
  2007年   36709篇
  2006年   37213篇
  2005年   35902篇
  2004年   33152篇
  2003年   31795篇
  2002年   30189篇
  2001年   49744篇
  2000年   50926篇
  1999年   43210篇
  1998年   12684篇
  1997年   11573篇
  1996年   11020篇
  1995年   11144篇
  1994年   10296篇
  1993年   9221篇
  1992年   33313篇
  1991年   32420篇
  1990年   31835篇
  1989年   30590篇
  1988年   27787篇
  1987年   27889篇
  1986年   25846篇
  1985年   24986篇
  1984年   18585篇
  1983年   15616篇
  1982年   9342篇
  1979年   16925篇
  1978年   12237篇
  1977年   10314篇
  1976年   9747篇
  1975年   10181篇
  1974年   12339篇
  1973年   11846篇
  1972年   10872篇
  1971年   10110篇
  1970年   9373篇
  1969年   8723篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
ObjectiveTo determine prognostic factors and survival patterns for different treatment modalities for nasal cavity (NC) and paranasal sinus (PS) mucosal melanoma (MM).MethodsPatients from 1973 to 2013 were analyzed using the Surveillance, Epidemiology, and End Results (SEER) database. Kaplan-Meier method and multivariable cox proportional hazard modeling were used for survival analyses.ResultsOf 928 cases of mucosal melanoma (NC = 632, PS = 302), increasing age (Hazard Ratio [HR]:1.05/year, p < 0.001), T4 tumors (HR: 1.81, p = 0.02), N1 status (HR: 6.61, p < 0.001), and PS disease (HR: 1.50, p < 0.001) were associated with worse survival. Median survival length was lower for PS versus NC (16 versus 26 months, p < 0.001). Surgery and surgery + radiation therapy (RT) improved survival over non-treatment or RT alone (p < 0.001). Adding RT to surgery did not yield a survival difference compared with surgery alone (p = 0.43). Five-year survival rates for surgery and surgery + RT were similar, at 27.7% and 25.1% (p = 0.43).ConclusionSurgery increased survival significantly over RT alone. RT following surgical resection did not improve survival.  相似文献   
2.
目的探讨通过下食管括约肌(lower esophageal sphincter,LES)扩张建立咽喉反流性疾病(laryngophyngeal reflux disease,LPRD)模型的可行性。方法18只新西兰白兔随机分为实验组10只和对照组8只,对实验组动物进行LES测压定位后,使用球囊对LES进行注水扩张,对照组同法置入球囊,但不进行球囊注水。扩张前1周及扩张后2周行咽喉及食管下段pH监测,LES平均静息压检测;扩张前1周、扩张后2周及8周行喉镜检查,进行喉镜下反流体征评分;扩张后8周处死动物,对其喉部及食管下段黏膜取材,光镜下观察其病理变化。结果扩张后pH监测验证实验组造模成功8只(80.0%,8/10),实验组扩张前咽喉酸反流时间百分比(%)、反流事件数(次)、反流最长时间(s)分别为0(0,0)、0(0,0)、0(0,0),扩张后分别为17.5(8.2,29.4)、3(1,5.5)、17.2(10.2,30.8),较扩张前增加,差异有统计学意义(P<0.01)。实验组扩张前食管下段pH监测酸反流时间百分比、反流事件数、反流最长时间分别为0(0,0.7)、0(0,1)、0(0,1.2),扩张后分别为23.1(4.8,49.5)、3(1,6)、25.9(11.5,56.8),较扩张前增加,差异有统计学意义(P<0.01)。实验组扩张前LES压力28.0±5.6 mmHg,较扩张后(17.2±3.3 mmHg)升高,差异有统计学差异(P=0.001);实验组扩张前RFS评分3.1±1.2分,扩张后2周为3.6±1.4分,扩张后8周为8.6±2.5分,扩张前和扩张后2周差异无统计学意义(P=0.482),但扩张前与扩张后8周差异有统计学意义(P=0.005)。病理检查示实验组喉部及食管黏膜均可观察到不同程度慢性炎症。结论食管下括约肌球囊扩张可安全、有效地建立LPRD动物模型。  相似文献   
3.
4.
Tamoxifen prevents recurrence of breast cancer and is suggested for preventive risk-reducing therapy. Tamoxifen reduces mammographic density, a proxy for therapy response, but little is known about its effects in remodelling normal breast tissue. Our study, a substudy within the double-blinded dose-determination trial KARISMA, investigated tamoxifen-specific changes in breast tissue composition and histological markers in healthy women. We included 83 healthy women randomised to 6 months daily intake of 20, 10, 5, 2.5, 1 mg of tamoxifen or placebo. The groups were combined to “no dose” (0-1 mg), “low-dose” (2.5-5 mg) or “high-dose” (10-20 mg) of tamoxifen. Ultrasound-guided biopsies were collected before and after tamoxifen exposure. In each biopsy, epithelial, stromal and adipose tissues was quantified, and expression of epithelial and stromal Ki67, oestrogen receptor (ER) and progesterone receptor (PR) analysed. Mammographic density using STRATUS was measured at baseline and end-of-tamoxifen-exposure. We found that different doses of tamoxifen reduced mammographic density and glandular-epithelial area in premenopausal women and associated with reduced epithelium and increased adipose tissue. High-dose tamoxifen also decreased epithelial ER and PR expressions in premenopausal women. Premenopausal women with the greatest reduction in proliferation also had the greatest epithelial reduction. In postmenopausal women, high-dose tamoxifen decreased the epithelial area with no measurable density decrease. Tamoxifen at both low and high doses influences breast tissue composition and expression of histological markers in the normal breast. Our findings connect epithelial proliferation with tissue remodelling in premenopausal women and provide novel insights to understanding biological mechanisms of primary prevention with tamoxifen.  相似文献   
5.
6.
Modified-release opioids are often prescribed for the management of moderate to severe acute pain following total hip and knee arthroplasty, despite recommendations against their use due to increasing concerns regarding harm. The primary objective of this multicentre study was to examine the impact of modified-release opioid use on the incidence of opioid-related adverse events compared with immediate-release opioid use, among adult inpatients following total hip or knee arthroplasty. Data for total hip and knee arthroplasty inpatients receiving an opioid analgesic for postoperative analgesia during hospitalisation were collected from electronic medical records of three tertiary metropolitan hospitals in Australia. The primary outcome was the incidence of opioid-related adverse events during hospital admission. Patients who received modified with or without immediate-release opioids were matched to those receiving immediate-release opioids only (1:1) using nearest neighbour propensity score matching with patient and clinical characteristics as covariates. This included total opioid dose received. In the matched cohorts, patients given modified-release opioids (n = 347) experienced a higher incidence of opioid-related adverse events overall, compared with those given immediate-release opioids only (20.5%, 71/347 vs. 12.7%, 44/347; difference in proportions 7.8% [95%CI 2.3–13.3%]). Modified-release opioid use was associated with an increased risk of harm when used for acute pain during hospitalisation after total hip or knee arthroplasty.  相似文献   
7.
目的分析某儿童专科医院住院患儿年龄、性别分布、各系统疾病谱顺位及其各年龄段变化趋势,为医院临床研究及疾病预防提供依据。方法回顾性分析2010年1月1日-2019年12月31日收治的743517例患儿病例资料,按年度、年龄段、性别对疾病构成进行χ2检验及构成比分析。结果住院患儿男性多于女性,男女性别比为1.99:1;2015年-2019年收治的患儿人数较2010年-2014年增长16.71%;2010年-2019年收治的住院患儿疾病谱首位为呼吸系统疾病(28%),2015年-2019年内分泌、营养和代谢疾病的疾病构成比较2010年-2014年明显增加(P<0.001);各年龄段疾病谱顺位不同;女童内分泌、营养和代谢疾病的发生率高于男童(P<0.001)。结论呼吸系统疾病仍为儿童常见病、多发病,在提高对呼吸系统疾病诊疗水平的同时,应加强对内分泌、营养和代谢疾病的防治。  相似文献   
8.
作为一种可以替代肺和心脏功能的呼吸循环支持技术,体外膜氧合(extracorporeal membrane oxygenation,ECMO)近年来在各种危重症呼吸、循环衰竭中的应用逐渐增多~([1-2])。ECMO主要包括动力泵、氧合器、各种管路及监测系统等,静脉血通过体外膜肺氧合后再回输给静脉或动脉,实施肺保护性通气,从而使肺脏得到休息,肺功能得以恢复~([3-4])。  相似文献   
9.
10.
Wu  Dan  Chen  Mengya  Chen  Shile  Zhang  Shimin  Chen  Yongheng  Zhao  Qian  Xue  Ke  Xue  Feng  Chen  Xiaosong  Zhou  Min  Li  Hao  Zheng  Jie  Le  Yunchen  Cao  Hua 《Clinical rheumatology》2022,41(10):3107-3117
Clinical Rheumatology - Extrahepatic tryptophan (Trp)-kynurenine (Kyn) metabolism via indoleamine 2,3-dioxygenase 1 (IDO1) induction was found to be associated with intrinsic immune regulation....  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