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   367649篇
  免费   54935篇
  国内免费   945篇
耳鼻咽喉   5139篇
儿科学   12593篇
妇产科学   6619篇
基础医学   56581篇
口腔科学   12758篇
临床医学   38131篇
内科学   79682篇
皮肤病学   14077篇
神经病学   41728篇
特种医学   14589篇
外国民族医学   6篇
外科学   57356篇
综合类   2556篇
现状与发展   2篇
一般理论   200篇
预防医学   22621篇
眼科学   7415篇
药学   26055篇
  2篇
中国医学   1435篇
肿瘤学   23984篇
  2023年   1605篇
  2022年   1795篇
  2021年   5296篇
  2020年   7986篇
  2019年   14610篇
  2018年   15659篇
  2017年   15868篇
  2016年   17576篇
  2015年   17581篇
  2014年   19273篇
  2013年   23844篇
  2012年   21344篇
  2011年   22877篇
  2010年   19277篇
  2009年   14184篇
  2008年   20172篇
  2007年   20268篇
  2006年   19608篇
  2005年   19453篇
  2004年   18439篇
  2003年   18029篇
  2002年   17352篇
  2001年   7578篇
  2000年   8539篇
  1999年   5664篇
  1998年   3796篇
  1997年   3035篇
  1996年   2532篇
  1995年   2225篇
  1994年   2037篇
  1993年   1975篇
  1992年   1595篇
  1991年   1470篇
  1990年   1268篇
  1989年   1290篇
  1988年   1159篇
  1987年   1216篇
  1986年   1053篇
  1985年   1292篇
  1984年   1382篇
  1983年   1197篇
  1982年   1431篇
  1981年   1335篇
  1980年   1203篇
  1979年   902篇
  1978年   869篇
  1977年   950篇
  1976年   803篇
  1975年   757篇
  1974年   693篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
BackgroundLittle is known about the extent of ordering low-value services by.PurposeTo compare the rates of low-value back images ordered by primary care physicians (PCMDs) and primary care nurse practitioners (PCNPs).MethodWe used 2012 and 2013 Medicare Part B claims for all beneficiaries in 18 hospital referral ?regions (HRRs) and a measure of low-value back imaging from Choosing Wisely. Models included random clinician effect and fixed effects for beneficiary age, disability, Elixhauser comorbidities, clinician sex, the emergency department setting, back pain visit volume, organization, and region (HRR).FindingsPCNPs (N = 231) and PCMDs (N = 4,779) order low-value back images at similar rates (NP: all images: 26.5%; MRI/CT: 8.4%; MD: all images: 24.5%; MRI/CT: 7.7%), with no detectable significant difference when controlling for covariates.DiscussionPCNPs and PCMDs order low-value back images at an effectively similar rate.  相似文献   
2.
3.
4.
5.
The majority of hip fractures in the elderly are the result of a fall from standing or from a lower height. Current injury models focus mostly on femur strength while neglecting subject-specific loading. This article presents an injury modeling strategy for hip fractures related to sideways falls that takes subject-specific impact loading into account. Finite element models (FEMs) of the human body were used to predict the experienced load and the femoral strength in a single model. We validated these models for their predicted peak force, effective pelvic stiffness, and fracture status against matching ex vivo sideways fall impacts (n = 11) with a trochanter velocity of 3.1 m/s. Furthermore, they were compared to sideways impacts of volunteers with lower impact velocities that were previously conducted by other groups. Good agreement was found between the ex vivo experiments and the FEMs with respect to peak force (root mean square error [RMSE] = 10.7%, R2 = 0.85) and effective pelvic stiffness (R2 = 0.92, RMSE = 12.9%). The FEMs were predictive of the fracture status for 10 out of 11 specimens. Compared to the volunteer experiments from low height, the FEMs overestimated the peak force by 25% for low BMI subjects and 8% for high BMI subjects. The effective pelvic stiffness values that were derived from the FEMs were comparable to those derived from impacts with volunteers. The force attenuation from the impact surface to the femur ranged between 27% and 54% and was highly dependent on soft tissue thickness (R2 = 0.86). The energy balance in the FEMS showed that at the time of peak force 79% to 93% of the total energy is either kinetic or was transformed to soft tissue deformation. The presented FEMs allow for direct discrimination between fracture and nonfracture outcome for sideways falls and bridge the gap between impact testing with volunteers and impact conditions representative of real life falls. © 2019 American Society for Bone and Mineral Research.  相似文献   
6.
7.
8.
9.
10.
Direct peroral cholangioscopy (POC) using an ultra‐slim upper endoscope is one modality of POC for intraductal endoscopic evaluation and treatment of the bile duct. Choledochoduodenostomy (CDS) is one modality of biliary bypass surgery that provides a new route to the bile duct. We carried out direct POC using an ultra‐slim upper endoscope without the use of accessories in 10 patients (four sump syndromes, three bile duct strictures and three intrahepatic duct stones) previously undergoing surgical CDS. Direct POC was successful in all patients. The use of an intraductal balloon catheter was required in one patient for advancement of the endoscope into the bile duct. Distal bile ducts with sump syndromes were cleared using baskets and water irrigation under direct POC. Cholangiocarcinoma was diagnosed in one patient with hilar bile duct stricture after cholangioscopic evaluation and a targeting forceps biopsy under direct POC. Intrahepatic duct stones were successfully extracted after intraductal fragmentation under direct POC. Oozing bleeding occurred during intraductal lithotripsy but stopped spontaneously. Direct POC using an ultra‐slim upper endoscope without the assistance of accessories can easily be carried out in patients undergoing CDS.  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