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   469篇
  免费   102篇
耳鼻咽喉   1篇
儿科学   22篇
妇产科学   3篇
基础医学   55篇
口腔科学   24篇
临床医学   54篇
内科学   43篇
皮肤病学   1篇
神经病学   22篇
特种医学   9篇
外科学   79篇
综合类   7篇
预防医学   120篇
眼科学   9篇
药学   21篇
中国医学   1篇
肿瘤学   100篇
  2023年   8篇
  2022年   8篇
  2021年   23篇
  2020年   6篇
  2019年   11篇
  2018年   22篇
  2017年   23篇
  2016年   28篇
  2015年   26篇
  2014年   39篇
  2013年   41篇
  2012年   27篇
  2011年   30篇
  2010年   18篇
  2009年   13篇
  2008年   22篇
  2007年   22篇
  2006年   14篇
  2005年   15篇
  2004年   13篇
  2003年   11篇
  2002年   10篇
  2001年   3篇
  1998年   3篇
  1997年   4篇
  1996年   5篇
  1995年   4篇
  1992年   4篇
  1990年   3篇
  1989年   3篇
  1988年   3篇
  1986年   3篇
  1985年   6篇
  1982年   6篇
  1981年   3篇
  1979年   6篇
  1978年   7篇
  1977年   4篇
  1976年   4篇
  1974年   7篇
  1973年   4篇
  1972年   4篇
  1971年   4篇
  1970年   9篇
  1969年   4篇
  1967年   3篇
  1966年   8篇
  1962年   2篇
  1961年   2篇
  1960年   3篇
排序方式: 共有571条查询结果,搜索用时 0 毫秒
21.
BackgroundThe purpose of this study was to examine the evolution of Legg–Calvé–Perthes’ disease (LCPD) among children from British Columbia (BC), Canada who were treated non-operatively and to compare the results to a previously conducted study in India.MethodsThis was a retrospective review of patients treated non-operatively for LCPD in BC between 1990 and 2006 compared with a cohort from India. Demographic and treatment information were collected from medical records. Radiographs were assigned modified Waldenstrom, Catterall, Salter–Thompson and Herring classifications and intra- and interobserver reliability were assessed. We evaluated epiphyseal extrusion (EE) and metaphyseal width (MW), and assessed radiographs using the Mose and modified Stulberg classifications.Results102 hips (90 patients) had radiographs available for evaluation. 95% of the BC cohort presented as Waldenstrom stages I and II, whereas, 90% of the Indian cohort presented as IIIa. Final EE was similar for both groups (BC 26.8%, India 27.3%) and final MW was 119% in both groups. Modified Waldenstrom and Herring classifications had substantial intra- and interobserver reliability, while Salter–Thompson and Catterall classifications had moderate agreement at best. Most hips were Catterall IV (80%) and Herring C (89%) for the BC cohort compared to only 44% and 43% of Indian hips, respectively. Most hips were irregular according to the Mose classification (BC 43%, India 52%) and aspherical according to the Stulberg classification (BC 78%).ConclusionsWe found similar radiographic progression and final radiographic appearances of LCPD in India and BC though differences in the distribution of the classification systems warrant further study.Supplementary InformationThe online version contains supplementary material available at 10.1007/s43465-021-00543-x.  相似文献   
22.
23.
We examined the expression of cyclin D1 in conjunction with β-catenin and the phosphorylated inactive form of glycogen synthase kinase 3β (GSK-3β) in benign, nonneoplastic thyroid tissue as well as papillary thyroid carcinoma primary tumors and nodal metastases. We aim to unravel the regulation of cyclin D1 and determine if this cell cycle protein is a useful biomarker for metastatic disease. It is clear that expression of cyclin D1 (P < .0001), β-catenin (P < .0001), and inactive form of GSK-3β (P < .0001) are significantly higher in papillary thyroid carcinoma primary tumors than in corresponding benign, nonneoplastic tissue thyroid specimens. Interestingly, β-catenin and cyclin D1 expressions in papillary thyroid carcinoma are correlated (P = .025), implying that β-catenin is a factor driving higher levels of cyclin D1 consistent with previous cell models linking Wnt/β-catenin signaling and cyclin D1 expression. Conversely, inactive form of GSK-3β expression does not correlate with cyclin D1 (P = .52) or β-catenin expression (P = .54). We also did not observe any relationship between tumor size and marker expression. Comparing papillary thyroid carcinoma primary tumors with or without nodal metastases, we did not see any differences in expression of inactive form of GSK-3β (P = .95), β-catenin (P = .14), or cyclin D1 (P = .46). However, in papillary thyroid carcinoma lymph node specimens, the up-regulation of cyclin D1 (P = .0083) was highly significant compared with primary tumors. pGSK-3β and β-catenin expression did not vary between primary tumors and nodal specimens. In conclusion, we have demonstrated that expression of cyclin D1 is linked to nodal metastases and that cyclin D1 levels are regulated by Wnt/β-catenin signaling. GSK pathway-mediated regulation of β-catenin or cyclin D1 expression does not appear operative in papillary thyroid carcinoma.  相似文献   
24.
ContextResearchers have traditionally used motion capture to quantify discrete data points (peak values) during hop testing. However, these analyses restrict the evaluation to a single time point (ie, certain percentage of stance) and provide only a narrow view of movement. Applying more comprehensive analyses may help investigators identify important characteristics that are masked by discrete analyses often used to screen patients for activity.ObjectiveTo examine the utility of functional data analyses to reveal asymmetries that are undetectable using discrete (ie, single time point) evaluations in participants with a history of anterior cruciate ligament reconstruction (ACLR) who achieved clinical hop symmetry.DesignCross-sectional study.SettingLaboratory.Patients or Other ParticipantsFifteen participants with unilateral ACLR (age = 21 ± 3 years, time from surgery = 4 ± 3 years) and 15 control participants without ACLR (age = 23 ± 2 years).Intervention(s)Lower extremity biomechanics during the triple–hop-for-distance task for the ACLR and contralateral limbs of patients and a representative limb of control participants were measured.Main Outcome Measure(s)Peak sagittal-plane joint power, joint work, and power profiles were determined.ResultsUsing discrete analyses, we identified lower peak knee power and work in the ACLR limb compared with the contralateral and control limbs (P < .05) but were unable to demonstrate differences at the ankle or hip. Using functional data analyses, we observed asymmetries at the ankle, knee, and hip between the ACLR and contralateral or control limbs throughout stance (P < .05), and it was revealed that these asymmetries stemmed from knee power deficits that were prominent during early loading.ConclusionsDespite achieving hop-distance symmetry, the ACLR knees absorbed less power. Although this information was revealed using discrete analyses, underlying asymmetries at the ankle and hip were masked. Using functional data analyses, we found interlimb asymmetries at the ankle, knee, and hip. Importantly, we found that functional data analyses more fully elucidated the extent and source of asymmetries, which can be used by clinicians and researchers alike to aid in clinical decision making.  相似文献   
25.
26.
27.
28.
PURPOSE: We examined the association between severity, accumulation, and timing of abuse in childhood and adolescence and smoking status among young women. METHODS: Retrospective self-reported childhood abuse was ascertained with the modified Conflict Tactics Scale from 91,286 Nurses Health Study II participants in 2001 (68,505 returned; 75.0% response rate). Childhood abuse was categorized by severity (mile/moderate/severe), type (physical/sexual), and timing (childhood/adolescence). Smoking status during adolescence was reported at baseline (1989). Logistic regression was used to predict smoking initiation by age 14 and smoking status between the ages of 15 and 19. RESULTS: A graded association between severity of abuse and early initiation of smoking (by age 14 years) was demonstrated (odds ratio [OR] = 1.9, 95% confidence interval [CI] = 1.7-2.1 for severe physical violence). Young women with both physical and sexual abuse were two times more likely to start smoking by age 14 than were those reporting no abuse (OR = 2.0, 95% CI = 1.8-2.3). Although abuse during childhood increased risk for adolescent smoking (OR = 1.7, 95% CI = 1.8-2.1) for those with childhood physical and sexual abuse, inclusion of adolescent physical and sexual abuse (OR = 2.2, 95% CI 2.1-2.4) diminished the impact of childhood abuse (OR = 1.1, 95% CI 1.1-1.2). The degree of familial emotional support was protective against smoking, and reduced the impact of abuse by 40% among those with high emotional support versus those without (p < .0001). CONCLUSIONS: A strong and graded association was observed between both severity and accumulation of abuse and the risk of early initiation of smoking among girls. Smoking status during late adolescence was more strongly associated with adolescent abuse than childhood abuse. Early smoking onset is associated with both heightened risk for disease in adolescence but also increased morbidity and mortality in adulthood. Identifying and intervening in potentially modifiable risk factors for smoking onset in young women, such as early-life physical and sexual abuse, and building familial strengths, such as emotional support, may have significant public health implications.  相似文献   
29.
30.
This study aimed to identify factors in school physical and social environments that may facilitate or compete with programs and policies to improve student physical activity and nutrition. Focus groups and interviews were conducted with students, faculty, and staff of two public middle schools. Participants identified numerous aspects of the school environments as significant. Competition, teasing and bullying, time, and safety were described as major barriers for students to be physically active during physical education class, on sports teams, and before and after school. The quality of the food served, easy access to nonnutritious snacks, limited time for lunch period, and weight concerns emerged as significant reasons why students do not eat nutritious meals in school. When developing programs and policies to improve the health of students, environmental influences that undermine efforts to improve student health behaviors must be addressed.  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