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   659篇
  免费   64篇
  国内免费   8篇
耳鼻咽喉   1篇
儿科学   19篇
妇产科学   11篇
基础医学   45篇
口腔科学   9篇
临床医学   46篇
内科学   91篇
皮肤病学   2篇
神经病学   12篇
特种医学   83篇
外科学   25篇
综合类   100篇
预防医学   181篇
眼科学   4篇
药学   38篇
  5篇
中国医学   10篇
肿瘤学   49篇
  2024年   4篇
  2023年   27篇
  2022年   51篇
  2021年   46篇
  2020年   44篇
  2019年   33篇
  2018年   26篇
  2017年   16篇
  2016年   15篇
  2015年   22篇
  2014年   55篇
  2013年   57篇
  2012年   37篇
  2011年   48篇
  2010年   34篇
  2009年   19篇
  2008年   24篇
  2007年   20篇
  2006年   20篇
  2005年   30篇
  2004年   20篇
  2003年   16篇
  2002年   12篇
  2001年   10篇
  2000年   4篇
  1999年   8篇
  1998年   7篇
  1997年   3篇
  1996年   3篇
  1995年   2篇
  1994年   7篇
  1993年   1篇
  1992年   1篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1981年   2篇
  1980年   1篇
  1978年   1篇
  1977年   1篇
  1974年   1篇
排序方式: 共有731条查询结果,搜索用时 359 毫秒
721.
《Vaccine》2023,41(7):1333-1341
IntroductionFew studies have assessed the impact of the coronavirus disease 2019 (COVID-19) pandemic on immunization coverage for adolescents, and little is known about how coverage has changed throughout the pandemic. We aimed to: (1) assess the change in coverage for school-based vaccines in Alberta, Canada resulting from the pandemic; (2) determine whether coverage differed by geographic health zone and school type; and (3) ascertain whether coverage has returned to pre-pandemic levels.MethodsUsing a retrospective cohort design, we used administrative health data to compare coverage for human papillomavirus (HPV) and meningococcal conjugate A, C, Y, W-135 (MenC-ACYW) vaccines between pre-pandemic (2017–2018 school year) and pandemic (2019–2020 and 2020–2021 school years) cohorts (N = 289,420). Coverage was also compared by health zone and authority type. The 2019–2020 cohort was followed over one year to assess catch-up.ResultsCompared to 2017–2018, immunization coverage for HPV was significantly lower in the 2019–2020 (absolute difference: 60.8%; 95% CI: 60.4–61.3%) and 2020–2021 cohorts (absolute difference: 59.9%; 95% CI: 59.4–60.3%). There was a smaller, significant decline in MenC-ACYW coverage comparing 2017–2018 to 2019–2020 (absolute difference: 6.1%; 95% CI: 5.6–6.5%) and 2020–2021 (absolute difference: 32.2%; 95% CI: 31.6–32.7%). Private schools had low coverage overall, while coverage fluctuated by zone. During follow-up of the 2019–2020 cohort, coverage for HPV and MenC-ACYW increased from 5.6% to 50.2%, and 80.7% to 83.0%, respectively.ConclusionThere was a substantial decrease in school-based immunization coverage during the COVID-19 pandemic, and coverage has not returned to pre-pandemic levels, suggesting further catch-up is needed.  相似文献   
722.
目的研究射波刀治疗计划系统中不同的小跳数(MU)射野删减优化方法对颅脑肿瘤计划剂量计算结果的影响。方法选取2021年6月至2022年2月在本院治疗的17例脑转移瘤患者, 针对每例患者使用射波刀VSI系统配备的MultiPlan计划系统设计计划作为无优化组, 每例初始计划生成后需删减一些小MU射野, 以优化计划的执行效率, 形成经验组和优化组。经验组按照经验将30 MU以下的射野删掉, 优化组将基于二阶导数方法计算的MU值以下的射野删掉, 最后统计对比3组计划参数。主要评估的参数包括节点数、射野数、总MU数、预计治疗时间、计划靶区(PTV)所接受的2%、95%体积的剂量PTVD2、PTVD95和平均剂量PTVDmean, 脑组织的平均剂量Dmean-Brain、适形指数(CI)、新适形指数(nCI)、梯度指数(GI)、覆盖率、脑干和左右眼晶状体的最大剂量(Dmax-BS、Dmax-LL和Dmax-RL), 距离PTV 20和40 mm的剂量壳的平均剂量Shell20和Shell40。结果采用的两种优化方法均可以满足>98%PTV接受处方剂量照射。无优化组、经验组和优化组在节点数(H...  相似文献   
723.
724.
目的 探讨老年甲状腺结节合并糖尿病患者外周血DNA甲基化/羟甲基化的检测及其临床意义。方法 选择2021年1月至2022年12月兰州市第一人民医院收治的136例老年甲状腺结节合并糖尿病患者为研究组,另选同期体检正常的135例老年人为对照组。采集所有入组对象一般资料,测定空腹血糖(FPG)、餐后2h血糖(2hPBG)、糖化血红蛋白(HbA1c)、甘油三酯(TG)、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)、游离三碘甲状腺原氨酸(FT3)、游离四碘甲状腺原氨酸(FT4)、促甲状腺激素(TSH)、甲状腺球蛋白抗体(TGAb)和甲状腺过氧化物酶抗体(TPOAb)水平。采用酶联免疫吸附法检测外周血全基因组5-甲基胞嘧啶(5-mC)、5羟甲基胞嘧啶(5-hmC)、细胞间黏附分子-1(ICAM-1)和甲基双加氧酶(TET2)水平。采用SPSS 21.0统计软件进行数据分析。根据数据类型,分别采用t检验、Mann-Whitney U检验或χ2检验进行组间比较。采用Spearman相关性分析探讨外周血5-mC、5-hmC与甲状腺结节合并糖尿病的相关性。结果 研究组患者FPG、2hPBG、HbA1c、TSH、TgAb和TPOAb水平均高于对照组,FT3低于对照组,差异均有统计学意义(P<0.05)。研究组外周血5-mC、5-hmC水平均高于对照组[6.64%(3.53%,8.53%)和4.28%(1.70%,7.20%);50.41%(35.00%,63.27%)和36.51%(17.81%,50.06%)];外周血TET2、ICAM-1水平均高于对照组[9.37(5.70,13.56)和4.56(1.52,6.99)pg/ml;4.98(2.35,7.01)和0.97(0.15,1.60)ng/ml],差异均有统计学意义(P<0.001)。Spearman相关性分析结果显示,5-mC与TgAb、TPOAb和HbA1c呈正相关(r=0.413,0.348,0.405;P<0.05);5-hmC与TgAb、TPOAb、FBG和2hPG呈正相关(r=0.375,0.406,0.376,0.311;P<0.05);5-mC与5-hmC呈正相关(r=0.256;P<0.05)。结论 老年甲状腺结节合并糖尿病患者外周血全基因组DNA甲基化与羟甲基化水平显著正常人群,外周血5-mC、5-hmC水平与老年甲状腺结节、糖尿病发病显著相关。  相似文献   
725.
PurposeTo compare tumor and ice-ball margin visibility on intraprocedural positron emission tomography (PET)/computed tomography (CT) and CT-only images and report technical success, local tumor progression, and adverse event rates for PET/CT-guided cryoablation procedures for musculoskeletal tumors.Materials and MethodsThis Health Insurance Portability and Accountability Act (HIPAA)–compliant and institutional review board–approved retrospective study evaluated 20 PET/CT-guided cryoablation procedures performed with palliative and/or curative intent to treat 15 musculoskeletal tumors in 15 patients from 2012 to 2021. Cryoablation was performed using general anesthesia and PET/CT guidance. Procedural images were reviewed to determine the following: (a) whether the tumor borders could be fully assessed on PET/CT or CT-only images; and (b) whether tumor ice-ball margins could be fully assessed on PET/CT or CT-only images. The ability to visualize tumor borders and ice-ball margins on PET/CT images was compared with that on CT-only images.ResultsTumor borders were fully assessable for 100% (20 of 20; 95% CI, 0.83–1) of procedures on PET/CT versus 20% (4 of 20; 95 CI, 0.057–0.44) of procedures on CT only (P < .001). The tumor ice-ball margin was fully assessable in 80% (16 of 20; 95% CI, 0.56–0.94) of procedures using PET/CT versus 5% (1 of 20; 95% CI, 0.0013–0.25) of procedures using CT only (P < .001). Primary technical success was achieved in 75% (15 of 20; 95% CI, 0.51–0.91) of procedures. There was local tumor progression in 23% (3/13; 95% CI, 0.050–0.54) of the treated tumors with at least 6 months of follow-up. There were 3 adverse events (1 Grade 3, 1 Grade 2, and 1 Grade 1).ConclusionsPET/CT-guided cryoablation of musculoskeletal tumors can provide superior intraprocedural visualization of the tumor and ice-ball margins compared with that provided by CT alone. Further studies are warranted to confirm the long-term efficacy and safety of this approach.  相似文献   
726.
Current global trends in physical activity levels demonstrate that the world is not on track to achieve the 2030 target set by the Global Action Plan. The Action Plan posited that physical activity should be an integral component of “daily lives” of all individuals “across the life course.” Potential contributions to achieve global physical activity goals include the utilization of compositional data analysis and life course epidemiology to provide a framework for the composite nature of physical activity and complex life course relationships. Combining these two traditionally disconnected fields represents a paradigm shift in physical activity research. Here, we discuss how these combined fields enable a reinterpretation of previous research findings and explore their impact on policy and potential advantages and challenges. Careful consideration needs to be given to the implications of both fields remaining disconnected and the alternate option of consolidation to realize ambitions.  相似文献   
727.
《Cancer radiothérapie》2023,27(3):196-205
PurposeTo evaluate the impact of dwell time deviation constraint (DTDC) on the quality of IPSA-optimized treatment plans in comparison with graphical plans using plan quality scores (PQS).Material and methodsSeventy optimized plans (graphical & IPSA with different DTDC values) of ten cervical cancer patients were generated. Various DVH parameters like D90, V100, V150, V200, V300 were compared to evaluate the impact of DTDC on target coverage and high dose regions inside target for different plans. Similarly, for the OAR dose, values of D2cc were compared. Various planning parameters like CI, COIN, DHI, DNR, ODI, EI and gain factor (GF) for different OARs were calculated. Based on these indices a plan quality score (PQS) was formulated and calculated. PQS values were used to see the impact of DTDC on plan quality of IPSA in comparison with dosimetric quality of graphical plan.ResultsWe have found that target coverage is similar for IPSA and graphically optimized treatment plans. However, dose homogeneity was improved in IPSA compared to graphical optimization whereas conformality was better in graphically optimized plans. OAR dose was less in IPSA plans. High-dose regions inside the target were also reduced in IPSA comparatively. However, IPSA plans optimized with various values of DTDC did not necessarily reduce high-dose regions beyond 0.6. Plan quality scores (PQS) were 6.31, 6.31, 6.34, and 6.17 for the graphically optimized plan, IPSA with DTDC values of 0.0, 0.4, and 1.0 respectively.ConclusionWe found that IPSA is dosimetrically advantageous over graphical optimization. IPSA with a DTDC value of 0.4 improved overall plan quality. However, DTDC value beyond 0.6 produces dosimetrically sub-optimal plans hence the use of DTDC should be very selective and limited.  相似文献   
728.
2019年底武汉市首现新型冠状病毒肺炎疫情,该病传染性极强,传播范围极广,严重威胁人类生命安全。藏医药在预防和治疗本病方面有独具特色的诊疗方案。笔者通过收集、整理藏区相关治疗方案,对藏医药防治新型冠状病毒肺炎的方案进行总结,以期为临床提供参考。  相似文献   
729.
Concepts of healthcare quality and health equity should be inextricably linked but are often pursued separately. Quality improvement (QI) can serve as a powerful means to eliminate health inequities by adopting an equity-focused lens to diagnose and address baseline disparities among pediatric populations using targeted interventions. QI and pediatric surgery practitioners should integrate concepts of equity at every stage of formulating a QI project including conceptualization, planning, and execution. Early adaptation of an equity conscious perspective using QI methodology can prevent exacerbation of preexisting disparities while improving overall outcomes.  相似文献   
730.
《Vaccine》2023,41(11):1799-1807
The 2021 Global Vaccine and Immunization Research Forum highlighted the considerable advances and recent progress in research and development for vaccines and immunization, critically reviewed lessons learned from COVID-19 vaccine programs, and looked ahead to opportunities for this decade.For COVID-19, decades of investments in basic and translational research, new technology platforms, and vaccines targeting prototype pathogens enabled a rapid, global response. Unprecedented global coordination and partnership have played an essential role in creating and delivering COVID-19 vaccines. More improvement is needed in product attributes such as deliverability, and in equitable access to vaccines.Developments in other priority areas included: the halting of two human immunodeficiency virus vaccine trials due to lack of efficacy in preventing infection; promising efficacy results in Phase 2 trials of two tuberculosis vaccines; pilot implementation of the most advanced malaria vaccine candidate in three countries; trials of human papillomavirus vaccines given in single-dose regimens; and emergency use listing of a novel, oral poliomyelitis type 2 vaccine. More systematic, proactive approaches are being developed for fostering vaccine uptake and demand, aligning on priorities for investment by the public and private sectors, and accelerating policy making.Participants emphasized that addressing endemic disease is intertwined with emergency preparedness and pandemic response, so that advances in one area create opportunities in the other. In this decade, advances made in response to the COVID-19 pandemic should accelerate availability of vaccines for other diseases, contribute to preparedness for future pandemics, and help to achieve impact and equity under Immunization Agenda 2030.  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