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   14868篇
  免费   1874篇
  国内免费   1054篇
耳鼻咽喉   151篇
儿科学   207篇
妇产科学   209篇
基础医学   2216篇
口腔科学   142篇
临床医学   2335篇
内科学   1706篇
皮肤病学   90篇
神经病学   500篇
特种医学   560篇
外国民族医学   4篇
外科学   2279篇
综合类   3245篇
现状与发展   4篇
预防医学   1753篇
眼科学   182篇
药学   1103篇
  22篇
中国医学   411篇
肿瘤学   677篇
  2024年   11篇
  2023年   124篇
  2022年   447篇
  2021年   485篇
  2020年   485篇
  2019年   291篇
  2018年   260篇
  2017年   247篇
  2016年   295篇
  2015年   356篇
  2014年   1069篇
  2013年   1097篇
  2012年   1568篇
  2011年   1660篇
  2010年   1271篇
  2009年   1172篇
  2008年   983篇
  2007年   1198篇
  2006年   935篇
  2005年   705篇
  2004年   657篇
  2003年   557篇
  2002年   485篇
  2001年   433篇
  2000年   306篇
  1999年   274篇
  1998年   133篇
  1997年   106篇
  1996年   74篇
  1995年   36篇
  1994年   26篇
  1993年   20篇
  1992年   23篇
  1991年   3篇
  1990年   1篇
  1989年   3篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
  目的  了解广州地区成年人睡眠模式的特征,并探讨睡眠模式对糖尿病(diabetes mellitus,DM)患病的影响。  方法  回顾性分析2012年11月至2013年12月在广东省人民医院参加体检的5 666名广州市职工的生活方式调查和体检资料。采用潜在类别分析(latent class analysis,LCA)对人群睡眠的潜在模式及分布特征进行探索性分析,通过多因素Logistic回归模型分析睡眠模式与DM的关系。  结果  LCA识别出5种睡眠模式,分别为“睡眠时间过短伴失眠”(类别1,5.6%)、“睡眠不足伴日间功能轻度减退”(类别2,20.4%)、“睡眠状况良好”(类别3,47.7%)、“睡眠不足伴日间功能障碍”(类别4,4.7%)、“睡眠不足伴夜间睡眠质量差”(类别5,21.6%)。调整相关混杂因素后,与类别3相比,类别1(OR=2.28,95%CI:1.51~3.43,P<0.001)、类别4(OR=2.48,95%CI:1.54~4.00,P<0.001)和类别5(OR=1.31,95%CI:1.01~1.71,P=0.045)人群罹患DM的风险升高。  结论  成年人群的睡眠因素之间存在关联,并表现为不同的睡眠模式;不良睡眠模式可增加DM患病风险。  相似文献   
2.
IntroductionPredicting pathological complete response (pCR) for patients receiving neoadjuvant chemotherapy (NAC) is crucial in establishing individualized treatment. Whole-slide images (WSIs) of tumor tissues reflect the histopathologic information of the tumor, which is important for therapeutic response effectiveness. In this study, we aimed to investigate whether predictive information for pCR could be detected from WSIs.Materials and methodsWe retrospectively collected data from four cohorts of 874 patients diagnosed with biopsy-proven breast cancer. A deep learning pathological model (DLPM) was constructed to predict pCR using biopsy WSIs in the primary cohort, and it was then validated in three external cohorts. The DLPM could generate a deep learning pathological score (DLPs) for each patient; stromal tumor-infiltrating lymphocytes (TILs) were selected for comparison with DLPs.ResultsThe WSI feature-based DLPM showed good predictive performance with the highest area under the curve (AUC) of 0.72 among the cohorts. Alternatively, the combination of the DLPM and clinical characteristics offered a better prediction performance (AUC >0.70) in all cohorts. We also evaluated the performance of DLPM in three different breast subtypes with the best prediction for the triple-negative breast cancer (TNBC) subtype (AUC: 0.73). Moreover, DLPM combined with clinical characteristics and stromal TILs achieved the highest AUC in the primary cohort (AUC: 0.82) and validation cohort 1 (AUC: 0.80).ConclusionOur study suggested that WSIs integrated with deep learning could potentially predict pCR to NAC in breast cancer. The predictive performance will be improved by combining clinical characteristics. DLPs from DLPM can provide more information compared to stromal TILs for pCR prediction.  相似文献   
3.
4.
5.
Reliable nasopharyngeal carcinoma (NPC) segmentation plays an important role in radiotherapy planning. However, recent deep learning methods fail to achieve satisfactory NPC segmentation in magnetic resonance (MR) images, since NPC is infiltrative and typically has a small or even tiny volume with indistinguishable border, making it indiscernible from tightly connected surrounding tissues from immense and complex backgrounds. To address such background dominance problems, this paper proposes a sequential method (SeqSeg) to achieve accurate NPC segmentation. Specifically, the proposed SeqSeg is devoted to solving the problem at two scales: the instance level and feature level. At the instance level, SeqSeg is forced to focus attention on the tumor and its surrounding tissue through the deep Q-learning (DQL)-based NPC detection model by prelocating the tumor and reducing the scale of the segmentation background. Next, at the feature level, SeqSeg uses high-level semantic features in deeper layers to guide feature learning in shallower layers, thus directing the channel-wise and region-wise attention to mine tumor-related features to perform accurate segmentation. The performance of our proposed method is evaluated by extensive experiments on the large NPC dataset containing 1101 patients. The experimental results demonstrated that the proposed SeqSeg not only outperforms several state-of-the-art methods but also achieves better performance in multi-device and multi-center datasets.  相似文献   
6.
Background Myxoma is the most frequent cardiac benign tumor which requires surgical removal even though in right atrium. Minimally invasive surgery has become the standard approach for removal of myxoma in our center. Herein, we report our initial experience of cardiac myxoma removal through mini-port totally thoracoscopic particular with focus on its feasibility, efficacy and short-term outcomes, as compared with median sternotomy. Methods From April 2015 to March 2019, 31 consecutive cases were ultimately identified and divided into two groups(Mini-port thoracoscopic group, n=14; versus conventional median sternotomic group, n=17). An echocardiography was routinely performed prior to discharge, at 1 st month, 6 th month, 12 th month and every year postoperatively. Retrospective analyses of perioperative data, postoperative outcomes and complications,and follow up data were performed. Results All the 31 patients successfully underwent right atrial myxoma removal surgery with no perioperative death, re-exploration for bleeding, residual mass or central nervous event in both groups. Intraoperative data from two group showed absence of significant difference except the intraoperative blood loss(150±50.01 m L in mini-port thoracoscopic group vs. 255.88±93.35 m L in conventional median sternomtomic group, P=0.01). There was no significant difference in perioperative blood transfusion and postoperative outcomes between the two groups. But the mini-port thoracoscopic group had a much less 24-hour postoperative drainage(136.71±148.20 m L vs. 341.17±211.29 m L, P=0.03). No significance difference could be identified between two groups about the incidence of postoperative morbidities and follow-up adverse events. Conclusion Totally mini-port video-assisted thoracoscopic approach for right atrial myxoma resection on peripheral cardiopulmonary bypass is feasible, effective with favorable safety in experienced cardiac center.[S Chin J Cardiol 2019;20(4):236-244]  相似文献   
7.
目的采用图像融合技术获得T2WI与T2WI-FS的融合图像,评估其在肛瘘及肛周结构显示中的优势。 方法2016年6月至2018年6月,前瞻性选择中山大学附属第一医院29例肛瘘患者进行肛管磁共振(MR)检查,采用图像融合技术获取T2WI与T2WI-FS的融合图像T2WI-Fusion,利用Fisher score算法计算瘘管及肛门括约肌的组织间分辨力Fisher值、脂肪与肛门括约肌间的Fisher值,评估融合图像中瘘管及肛周结构的显示情况。采用改进的双刺激连续质量量表(DSCQS)对T2WI-FS、T2WI、增强3D-VIBE和T2WI-Fusion序列图像进行主观图像质量评价。 结果29例患者均成功获得T2WI与T2WI-FS的融合图像T2WI-Fusion。T2WI-Fusion、T2WI瘘管与括约肌间Fisher均值分别为6.46、3.31,T2WI-Fusion图像对瘘管的显示优于T2WI序列图像(P<0.001)。T2WI-Fusion、T2WI-FS脂肪与括约肌间Fisher均值分别为10.61、2.45,T2WI-Fusion图像对括约肌的显示优于T2WI-FS序列图像(P<0.001)。T2WI-Fusion对瘘管与括约肌的图像质量评价总评分均高于T2WI-FS、T2WI、增强3D-VIBE序列(P<0.001)。 结论MRI图像融合技术同时具备T2WI及T2WI-FS的优势,无需增加扫描序列及扫描时间,且操作简单,花费时间短,显著提高病变及肛周解剖结构的对比度和图像质量。  相似文献   
8.
ObjectiveImprovement in the quality of life is reflected in the narrowing of the gap between health-adjusted life expectancy (HALE) and life expectancy (LE). The effect of megacity expansion on narrowing the gap is rarely reported. This study aimed to disclose this potential relationship.MethodsAnnual life tables were constructed from identified death records and population counts from multiple administrative sources in Guangzhou, China, from 2010 to 2020. Joinpoint regression was used to evaluate the temporal trend. Generalized principal component analysis and multilevel models were applied to examine the county-level association between the gap and social determinants.ResultsAlthough LE and HALE in megacities are increasing steadily, their gap is widening. Socio-economic and health services are guaranteed to narrow this gap. Increasing personal wealth, a growing number of newborns and healthy immigrants, high urbanization, and healthy aging have helped in narrowing this gap.ConclusionIn megacities, parallel LE and HALE growth should be highly considered to narrow their gap. Multiple social determinants need to be integrated as a whole to formulate public health plans.  相似文献   
9.
10.
目的研究快速成型(RP)技术辅助下制作的个体化假体复合珊瑚羟基磷灰石(CHA)、重组人骨形成蛋白2(rhBMP-2)修复兔下颌骨缺损的成骨效果。 方法以27只新西兰大白兔为实验对象,随机数字表法平均分成3组(每组9只),全部建立下颌骨连续性缺损模型,并在兔下颌骨缺损区分别植入个体化假体+自体骨(A组)、个体化假体+CHA(B组)、个体化假体+CHA+rhBMP-2(C组)。分别于术后4、12、24周3个时间点处死动物取材,进行大体标本观察,以及骨钙素(OC)、Ⅰ型胶原(COL-1)的免疫组化观察,分别比较各组修复骨缺损的能力,并对实验数据进行重复测量设计资料的单因素方差分析。 结果术后24周各组实验兔外形均对称,通过OC及COL-1的吸光度检测,骨缺损区均有大量新骨形成,A组(0.537 ± 0.010)、C组(0.530 ± 0.010)可见大量骨小梁及编织骨结构,缺损区的新骨OC、COL-1的免疫组化观察基本一致,差异无统计学意义(t = 0.007,P>0.05);但A组强于B组(0.415 ± 0.009,t = 0.122,P<0.001);C组也强于B组(t = 0.121,P<0.001),差异均有统计学意义。 结论在兔下颌骨缺损修复中,通过RP技术和组织工程技术相结合,CHA复合rhBMP-2后成骨能力明显增强,成骨效能肯定,为后期的临床应用提供可靠的实验基础。  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