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   718713篇
  免费   67509篇
  国内免费   20332篇
耳鼻咽喉   9776篇
儿科学   15750篇
妇产科学   12885篇
基础医学   52199篇
口腔科学   15483篇
临床医学   70924篇
内科学   88509篇
皮肤病学   7480篇
神经病学   23388篇
特种医学   25947篇
外国民族医学   347篇
外科学   114072篇
综合类   96228篇
现状与发展   83篇
一般理论   31篇
预防医学   52897篇
眼科学   10827篇
药学   62315篇
  687篇
中国医学   37647篇
肿瘤学   109079篇
  2024年   857篇
  2023年   12193篇
  2022年   18073篇
  2021年   33389篇
  2020年   30122篇
  2019年   32936篇
  2018年   27959篇
  2017年   26744篇
  2016年   28729篇
  2015年   32450篇
  2014年   55175篇
  2013年   53452篇
  2012年   49937篇
  2011年   48682篇
  2010年   40304篇
  2009年   38168篇
  2008年   36406篇
  2007年   36025篇
  2006年   31210篇
  2005年   24482篇
  2004年   18270篇
  2003年   15499篇
  2002年   12559篇
  2001年   10915篇
  2000年   9346篇
  1999年   7405篇
  1998年   6436篇
  1997年   5724篇
  1996年   4665篇
  1995年   4765篇
  1994年   4248篇
  1993年   3394篇
  1992年   3367篇
  1991年   3054篇
  1990年   2650篇
  1989年   2524篇
  1988年   2306篇
  1987年   2082篇
  1986年   1739篇
  1985年   3744篇
  1984年   4065篇
  1983年   2727篇
  1982年   3233篇
  1981年   2694篇
  1980年   2316篇
  1979年   1997篇
  1978年   1575篇
  1977年   1367篇
  1976年   1371篇
  1975年   945篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
ObjectiveThis study aimed to analyze national influenza infection control policy documents within aged care settings by identifying the consistencies, inconsistencies, and gaps with the current evidence and by evaluating methodological quality. Aged care providers can use these findings to identify their policy documents' strengths and weaknesses.DesignA quality and content analysis of national level policy documents.Setting and ParticipantsAged care settings rely on national agencies' policy recommendations to control and prevent outbreaks. There is limited research on the effectiveness of control measures to prevent and treat influenza within aged care settings. Because of the complexities around aged care governance, the primary responsibility in developing a comprehensive facility-level, infection-prevention policy, falls to the providers.MethodsThe analysis was conducted using the (1) International Appraisal of Guidelines, Research and Evaluation assessment tool, containing 23 items across 6 domains; and the (2) Influenza Related Control Measures in Aged Care settings checklist, developed by the authors, with 82 recommendations covering: medical interventions, nonmedical interventions, and physical layout.ResultsThere were 19 documents from 9 different high-income countries, with a moderately high methodological quality in general. The quality assessment's average score was 40.2% (95% CI 31.9%–44.7%). “Stakeholder involvement” ranked third, and “Editorial independence” and “Rigor of development” had the lowest average scores across all domains. The content analysis' average score was 37.2% (95% CI 10.5%–21.5%). The highest scoring document (59.1%) included term definitions, cited evidence for recommendations, and clear measurable instructions. “Physical Layout” had the least coverage and averaged 21.9% (95% CI 4.2%–37.5%), which shows a substantial gap in built environment recommendations.Conclusions and ImplicationsExisting policy documents vary in their comprehensiveness. The higher scoring documents provide an ideal model for providers. The checklist tools can be used to assess and enhance documents. Further research on document end-user evaluation would be useful, as there is room for improvement in methodological quality and coverage of recommendation coverage, especially related to physical layout.  相似文献   
72.
73.
PurposeTo evaluate the effectiveness and safety of fluoroscopy-guided percutaneous high ligation (FPHL) combined with fluoroscopy-guided foam sclerotherapy (FGFS) to treat varicose veins of the great saphenous veins (GSVs).Materials and MethodsThis was a retrospective study of 113 patients (mean age, 62.1 ± 10.8 years; 60 men) with varicose veins of the GSVs (133 limbs) that were treated with FPHL combined with FGFS between April 1 and October 31, 2019. Demographic and clinical data were collected from these patients before the FPHL procedure, after which FGFS was performed. The preterminal GSV was ligated percutaneously by a percutaneously-positioned polypropylene ligature under fluoroscopic guidance. The outcome of ligation was confirmed by venography. Then, foam sclerotherapy was performed under fluoroscopy. At 1-year follow-up, GSV occlusion was evaluated by ultrasound. The venous clinical severity scores (VCSSs) were compared between the preoperative and 1-year follow-up periods.ResultsThe technical success rate was 100% (133 limbs). Complete 12-month follow-up was available for 112 limbs (84.2%) and 103 of these limbs (92.0%) remained occluded during this period. The VCSS improved from 4.71 ± 2.15 to 0.74 ± 0.60 (V = 6328, P < .001). During follow-up, there were 16 limbs with thrombophlebitis and 38 limbs with saphenous junction pain; these events were alleviated within 2 weeks of the procedure. There was no deep venous thrombosis or other severe adverse events.ConclusionsFPHL combined with FGFS to treat varicose veins in the GSVs achieved an occlusion rate of 92% and improved the clinical symptoms within 1 year; this minimally-invasive procedure was safe and effective.  相似文献   
74.
目的:挖掘并筛选与甲状腺乳头状癌(papillary thyroid carcinoma,PTC)淋巴结转移相关的突变基因及其潜在的机制。方法:从TCGA数据库获得377例PTC患者的测序数据及完整的临床资料,并分为淋巴结转移组(LM,n=212)与无淋巴结转移组(NLM,n=165)。利用R语言(v3.6.2)对转移组特有的突变基因进行富集分析。采用String在线软件绘制蛋白互作网络,Cytoscape软件筛选网络中的核心基因。在UALCAN网站上验证基因表达量与淋巴结转移之间的关系。利用荧光实时定量PCR测定候选基因在细胞系中mRNA的表达量。结果:一共筛选出1197个仅在LM组发生突变的基因,它们主要富集在黏着连接、细胞黏附分子(cell adhesion molecules,CAMs)通路。CAMs通路的核心基因ITGB1与VCAN的表达量与淋巴结转移相关。与正常甲状腺细胞系相比,VCAN基因在PTC细胞系TPC-1和B-CPAP中mRNA的表达量较高,尤其是B-CPAP细胞系。结论:CAMs通路可能是PTC淋巴结转移相关机制之一,其中VCAN基因可能是潜在的分子标志物。  相似文献   
75.
Background: The current disadvantages (high cost, toxicity, resistance) of chemotherapy for gastric cancer opted people for alternative therapy from natural source. Curcumin (natural product) possess multiple biological activities but low bio-availability limits their uses as therapeutic. The Nano-formulation of curcumin increased the bioavailability and productivity of anti-cancer and anti-bacterial properties. The present study was initiated to determine the anti-cancer and anti-bacterial effect of Nano curcumin against gastric cancer and H. pylori. Methods: Curcumin loaded PLGA nanoparticles (CUR-NPs) was prepared by single emulsion solvent evaporation method. The MIC were determined using agar dilution method to find the anti-H. Pylori activity of Nano curcumin. The cytotoxicity of Nano curcumin was evaluated by MTT assay and the apoptotic effect (cell cycle arrest and morphology change) was shown by PI staining and microscopy. Results: The MIC of nanocurcumin and curcumin for all four H. pylori strains were 8 µg/ml and 16 µg/ml respectively. The inhibition rate of gastric cancer cells after treatment with curcumin was increased from 6% to 67% for 24h, from 8% to 75% for 48h, from 10% to 83% for 72h. In case of nanocurcumin, the inhibition rate increased from 7% to 69% for 24h, 11% to 87% for 48h and 16% to 97% for 72h. The IC50 of curcumin and Nano-curcumin were 24.20 µM and 18.78 µM respectively for 72 h. The population of cells in sub-G0 population increased from 4.1% in the control group to 24.5% and 57.8% when treated with curcumin and nanocurcumin respectively. After 72h of treatment with nanocurcumin, the apoptotic cells population increased as compared to native curcumin treated cells. Conclusion: The Nano curcumin might be used as a potential therapeutics against gastric cancer and H. Pylori. There is need of further in vivo study in order to validate CUR-NPs activity.  相似文献   
76.
前列腺癌(prostate cancer, PCa)是中老年男性常见恶性肿瘤之一,目前尚缺乏有效的晚期癌症治疗方法,因此早期诊断对于降低PCa死亡率至关重要。近年来,较多研究开发出多种新型诊断方法以改善对PCa诊断的准确性,同时避免过度诊疗,但其有效性及实用性尚需进一步验证。本文对目前新型生物标志物、联合成像技术及风险预测模型等的早期诊断技术进行总结,以期为临床研究提供指导作用。  相似文献   
77.
对比增强能谱X线摄影(contrast enhancement spectral mammography, CESM)是在普通X线检查的基础上结合血管造影剂进行检查的一种新技术,是通过注射造影剂有效消除组织重叠对病灶的遮盖,实现对肿块真实形态显示,并提供血供信息。目前临床上对CESM进行了一系列的研究,本文就CESM成像原理、对乳腺癌的诊断、应用前景几个方面进行综述。  相似文献   
78.
目的:分析基于几何不确定性的鲁棒优化计划对肝癌立体定向放疗(SBRT)剂量分布的影响。方法:选取12例肝癌SBRT患者,对每例制作3个调强计划:①基于PTV(ITV-PTV 5 mm)的常规优化(PTV-Based Plan);②基于ITV非均匀几何不确定性(本中心计算的不确定性值:进出方向7 mm,左右和前后方向4 mm)的鲁棒优化(Robust Planactual);③基于ITV均匀5 mm几何不确定性的鲁棒优化(Robust Plan5 mm)。所有计划都以95%的PTV满足处方剂量作为目标,以等中心均匀偏移4、5、7 mm计算扰动剂量评估鲁棒性。结果:计划①②③的均匀性指数(HI)分别为0.083±0.027、0.099±0.035、0.096±0.026,不具有统计学意义;计划①②③的适形性指数(CI)分别为0.98±0.02、1.02±0.05、1.00±0.04,计划②③相对于计划①的CI具有统计学意义。计划③的正常肝组织平均受量和V2500相对于计划①②分别下降了4.1%、2.5%和5.4%、3.0%,且具有统计学意义(P=0.034、P=0.021和P=0.004、P=0.004),计划②相对于计划①的正常肝组织平均受量和V2500不具有统计学意义(P=0.308和P=0.182),但下降了1.6%和2.5%。对于其鲁棒性,计划②③的5 mm-D99%、5 mm-D98%、5 mm-D95%的剂量-体积直方图带宽(DVHBW)差值相对于计划①更小,随着摆位不确定度的增大,其DVHBW差值越大。结论:在肝脏SBRT治疗中,采用鲁棒优化能够提高靶区剂量分布质量,即使在摆位不确定度有所增加的情况下,仍可以保证ITV的剂量覆盖同时不增加正常组织的照射剂量。  相似文献   
79.
IntroductionThe Modena bleeding score is a categorical rating scale that allows the assessment of the surgical field in relation to bleeding during endoscopic surgery. It has recently been presented and validated in the field of endoscopic ear surgery by the present authors. The Modena bleeding score provides five grades for rating the surgical field during endoscopic procedures (from grade 1 ? no bleeding to grade 5 ? bleeding that prevents every surgical procedure except those dedicated to bleeding control).ObjectiveThe aim of this study was to validate the Modena bleeding score in the setting of endoscopic sinus surgery.MethodsFifteen three-minute videos of endoscopic sinus surgery procedures (each containing three bleeding situations) were evaluated by 15 specialists, using the Modena bleeding score. Intra and inter-rater reliability were assessed, and the clinical validity of the Modena bleeding score was calculated using a referent standard.ResultsThe data analysis showed an intra-rater reliability ranging from 0.6336 to 0.861. The inter-rater reliability ranged from 0.676 to 0.844. The clinical validity was α = 0.70; confidence limits: 0.64 ? 0.75, corresponding to substantial agreement.ConclusionThe Modena bleeding score is an effective method to score bleeding during endoscopic sinus surgery. Its application in future research could facilitate the performance and efficacy assessment of surgical techniques, materials or devices aimed to bleeding control during endoscopic sinus surgery.  相似文献   
80.
卵巢囊肿(ovarian cyst)是妇科常见疾病,可发生于任何年龄段,以育龄期最为多见。卵巢囊肿多为良性,除个别因扭转、破裂等表现为急腹症外,一般无特异性症状。部分功能性卵巢囊肿可伴有月经紊乱、腹部不适等症状,多数随着囊肿的消退而逐渐消失。  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