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   212120篇
  免费   29189篇
  国内免费   7268篇
耳鼻咽喉   1702篇
儿科学   1570篇
妇产科学   5150篇
基础医学   15348篇
口腔科学   2185篇
临床医学   16916篇
内科学   21841篇
皮肤病学   1373篇
神经病学   1209篇
特种医学   6168篇
外国民族医学   270篇
外科学   30294篇
综合类   28496篇
现状与发展   39篇
一般理论   3篇
预防医学   9737篇
眼科学   119篇
药学   15281篇
  140篇
中国医学   5636篇
肿瘤学   85100篇
  2024年   188篇
  2023年   4320篇
  2022年   6106篇
  2021年   10717篇
  2020年   10737篇
  2019年   9698篇
  2018年   9278篇
  2017年   9783篇
  2016年   10533篇
  2015年   12124篇
  2014年   17542篇
  2013年   17579篇
  2012年   14048篇
  2011年   14281篇
  2010年   10413篇
  2009年   10606篇
  2008年   10936篇
  2007年   10416篇
  2006年   9114篇
  2005年   7532篇
  2004年   6236篇
  2003年   5193篇
  2002年   4439篇
  2001年   4109篇
  2000年   3466篇
  1999年   2805篇
  1998年   2209篇
  1997年   1924篇
  1996年   1608篇
  1995年   1719篇
  1994年   1435篇
  1993年   1089篇
  1992年   946篇
  1991年   886篇
  1990年   670篇
  1989年   616篇
  1988年   522篇
  1987年   434篇
  1986年   311篇
  1985年   401篇
  1984年   343篇
  1983年   219篇
  1982年   227篇
  1981年   206篇
  1980年   186篇
  1979年   123篇
  1978年   82篇
  1977年   74篇
  1976年   65篇
  1975年   41篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
《Cancer cell》2022,40(10):1223-1239.e6
  1. Download : Download high-res image (205KB)
  2. Download : Download full-size image
  相似文献   
74.
《Immunity》2022,55(9):1594-1608.e6
  1. Download : Download high-res image (141KB)
  2. Download : Download full-size image
  相似文献   
75.
《Radiography》2022,28(3):718-724
IntroductionLiver cancer lesions on Computed Tomography (CT) withholds a great amount of data, which is not visible to the radiologists and radiographer. Radiomics features can be extracted from the lesions and used to train Machine Learning (ML) algorithms to predict between tumour and liver tissue. The purpose of this study was to investigate and classify Radiomics features extracted from liver tumours and normal liver tissue in a limited CT dataset.MethodsThe Liver Tumour Segmentation Benchmark (LiTS) dataset consisting of 131 CT scans of the liver with segmentations of tumour tissue and healthy liver was used to extract Radiomic features. Extracted Radiomic features included size, shape, and location extracted with morphological and statistical techniques according to the International Symposium on Biomedical Imaging manual. Relevant features was selected with chi2 correlation and principal component analysis (PCA) with tumour and healthy liver tissue as outcome according to a consensus between three experienced radiologists. Logistic regression, random forest and support vector machine was used to train and validate the dataset with a 10-fold cross-validation method and the Grid Search as hyper-parameter tuning. Performance was evaluated with sensitivity, specificity and accuracy.ResultsThe performance of the ML algorithms achieved sensitivities, specificities and accuracy ranging from 96.30% (95% CI: 81.03%–99.91%) to 100.00% (95% CI: 86.77%–100.00%), 91.30% (95% CI: 71.96%–98.93%) to 100.00% (95% CI: 83.89%–100.00%)and 94.00% (95% CI: 83.45%–98.75%) to 100.00% (95% CI: 92.45%–100.00%), respectively.ConclusionML algorithms classifies Radiomics features extracted from healthy liver and tumour tissue with perfect accuracy. The Radiomics signature allows for a prognostic biomarker for hepatic tumour screening on liver CT.Implications for practiceDifferentiation between tumour and liver tissue with Radiomics ML algorithms have the potential to increase the diagnostic accuracy, assist in the decision-making of supplementary multiphasic enhanced medical imaging, as well as for developing novel prognostic biomarkers for liver cancer patients.  相似文献   
76.
目的 观察结肠癌HCT116细胞健脾消癌方的条件培养液对HUVEC细胞管腔形成的影响,从PI3K/Akt生物轴调控角度探讨其作用机制。方法 培养HCT116细胞,细胞设3组:对照组,健脾消癌方组(加入15%健脾消癌方含药血清)及人参皂苷Rg3组;制备HCT116细胞健脾消癌方条件培养液(分组及制备方法见实验方法),用条件培养液干预HUVEC(脐静脉内皮细胞,Human Umbilical Vein Endothelial Cells),Matrigel基质胶法检测HCT116细胞健脾消癌方条件培养液对HUVEC小管形成的影响。随后采用蛋白免疫印迹法(Western blot)检测各组HCT116细胞磷脂酰肌醇3-激酶(PI3K)、蛋白激酶B(Akt)、p-Akt、VEGF(血管内皮生长因子,Vascular endothelial growth factor)蛋白表达。最后在结肠癌HCT116荷瘤小鼠中验证健脾消癌方对肿瘤生长速度的影响,并经瘤组织VEGF蛋白表达、CD31免疫组化染色检测肿瘤内血管生成情况。结果 模型组HUVEC细胞管腔形成较空白血清组显著增加(P<0.05);健脾消癌方组及人参皂苷Rg3组较模型组HUVEC细胞管腔形成显著减少(P<0.01)。p-Akt和VEGF蛋白表达水平模型组高于空白血清组(P<0.05),健脾消癌方组及人参皂苷Rg3组显著低于模型组(P<0.01);PI3K、Akt蛋白表达量组间差异无统计学意义。与对照组比较,模型组荷瘤小鼠肿瘤体积显著性增大,瘤组织内VEGF表达、CD31阳性面积显著性增加,差异有统计学意义(P<0.05);与模型组比较,健脾消癌方组及人参皂苷Rg3组荷瘤小鼠肿瘤体积显著减小,瘤组织内VEGF表达、CD31阳性面积降低,差异有统计学意义(P<0.05)。结论 健脾消癌方可抑制肿瘤的血管生成和生长,其作用机制可能与PI3K/Akt生物轴调控VEGF表达有关。  相似文献   
77.
目的 分析不同特征的结直肠癌患者就医行为选择在中医院(含中西医结合医院)、西医院及肿瘤专科医院间的差异,为合理引导结直肠癌患者适宜就医及制订相关政策提供依据。方法 收集北京地区2018年1月-2019年12月17家三级甲等医院21894例首诊结直肠癌成年住院患者的病案首页数据,采用EmpowerStats 2.0对数据进行描述性分析。结果 21894例结直肠癌患者中就诊于中医院的有862例(3.93%),西医院的有8723例(39.85%),肿瘤专科医院的有12309例(56.22%)。对于不同医疗机构,男性占比均大于女性,58-68岁患者占比最大。且结直肠癌患者年龄、医疗付款方式及肿瘤分期在不同医疗机构间的分布存在差异(P<0.001)。西医院及肿瘤专科医院结直肠癌Ⅲ期患者占比最大,而就诊于中医院患者中结直肠癌Ⅳ期最多。从地域分布来看,异地就诊比例(57.32%)大于本地,且就诊于肿瘤专科医院的患者中73.66%来自外地。患者来源前三名分别是北京市、河北省及内蒙古自治区。而在北京市内,西医院患者主要来源于朝阳区、海淀区及西城区,中医院患者主要来源于海淀区、朝阳区及丰台区,肿瘤专科医院则主要来源于朝阳区、海淀区及丰台区。结论 应大力倡导年轻以及早期结直肠癌患者向中医院分流,充分施展中医药在结直肠癌患者中的治疗优势;发挥三级医院带动作用,建立对口帮扶医院,减少不必要的跨省流动及提倡结直肠癌的早筛早治,以降低结直肠癌死亡率。  相似文献   
78.
目的探讨乙肝相关性肝癌临床病理学特征与溶血磷脂酸(LPA)和高敏C反应蛋白(hs-CRP)表达的相关性。方法选取2019年1月至2020年1月间河南省驻马店市中心医院收治的198例乙肝相关性肝癌患者作为乙肝组,198例酒精相关性肝癌患者作为酒精组。两组患者都进行血清hs-CRP和LPA表达检测,调查患者的病理学特征并进行相关性分析。结果乙肝组患者血清hs-CRP和LPA含量均高于酒精组,差异均有统计学意义(均P <0.05)。两组患者血清ALP、AFP、ALT、AST和GGT含量比较,差异均无统计学意义(P> 0.05)。乙肝组不同临床分期和组织学分化患者的血清hs-CRP和LPA含量比较,差异均有统计学意义(均P <0.05)。乙肝组患者的临床分期和组织学分化与血清hs-CRP和LPA表达均存在相关性,差异均有统计学意义(均P <0.05)。患者的临床分期和组织学分化均为影响hs-CRP和LPA表达的重要因素,差异均有统计学意义(均P <0.05)。结论相对于酒精相关性肝癌,乙肝相关性肝癌的血清hs-CRP和LPA呈现高表达,与患者的临床病理学特征存在相关性。  相似文献   
79.
Objective: To perform a scoping review of the applicability of the Gail model in different countries for different ethnicities. Methods: The review was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) checklist and search strategies based on the PICOS approach. The reviewed articles were included if they were published between 2013 and 2018 in English, Portuguese, or Spanish; were original articles available in full online; and described the use of the Gail model. The PubMed, Embase, and Web of Science data bases were searched. Results: A total of 38 articles eligible for analysis were identified, of which 16 used the Gail model to assess breast cancer risk in women, eight analyzed the applicability of this tool in their population, seven compared the tool and/or modified it according to the specific risk factors of their population, and seven cited the model in determining eligibility for chemoprevention. Conclusion: The Gail model has different applicabilities Greater effectiveness and breast cancer risk are found in developed countries.  相似文献   
80.
Therapies based on the use of immune checkpoint inhibitors (ICIs), such as nivolumab, pembrolizumab, ipilimumab, atezolizumab, avelumab, and durvalumab, have proven effective in the treatment of metastatic urological neoplasms. Recently, it has been hypothesized that the use of this type of treatment prior to surgery could lead to an increased difficulty in renal and bladder surgeries. The literature concerning this topic, however, is still scarce and non-consensual. In our systematic review, we used the PRISMA guidelines methodology to search the pertinent literature available up to June 18, 2020 in PubMed. Additionally, we searched the related grey literature in the abstracts of the meetings of the American Society of Clinical Oncology (ASCO), American Society of Clinical Oncology Genitourinary (ASCO-GU), European Society of Medical Oncology (ESMO), and American Urological Association (AUA) from 2015 to 2020. We were able to find only 16 publications that addressed the use of ICIs prior to surgery in kidney and bladder neoplasms. The results were conflicting, and usually the issue of surgical difficulties after the use of ICIs was not directly approached. We hope that our publication may raise the awareness towards the need to further investigate the effects of neoadjuvant ICIs on surgical outcomes in urologic cancers.  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