全文获取类型
收费全文 | 153000篇 |
免费 | 12816篇 |
国内免费 | 4774篇 |
专业分类
耳鼻咽喉 | 1063篇 |
儿科学 | 2858篇 |
妇产科学 | 1489篇 |
基础医学 | 23661篇 |
口腔科学 | 2981篇 |
临床医学 | 15381篇 |
内科学 | 19560篇 |
皮肤病学 | 1517篇 |
神经病学 | 7505篇 |
特种医学 | 3202篇 |
外国民族医学 | 22篇 |
外科学 | 12706篇 |
综合类 | 24241篇 |
现状与发展 | 11篇 |
一般理论 | 25篇 |
预防医学 | 10668篇 |
眼科学 | 4229篇 |
药学 | 17000篇 |
14篇 | |
中国医学 | 8086篇 |
肿瘤学 | 14371篇 |
出版年
2023年 | 1739篇 |
2022年 | 2637篇 |
2021年 | 4995篇 |
2020年 | 4731篇 |
2019年 | 5165篇 |
2018年 | 5054篇 |
2017年 | 4891篇 |
2016年 | 4940篇 |
2015年 | 5005篇 |
2014年 | 7886篇 |
2013年 | 8868篇 |
2012年 | 7422篇 |
2011年 | 8574篇 |
2010年 | 7447篇 |
2009年 | 7348篇 |
2008年 | 7419篇 |
2007年 | 8450篇 |
2006年 | 7776篇 |
2005年 | 7783篇 |
2004年 | 6805篇 |
2003年 | 6043篇 |
2002年 | 4457篇 |
2001年 | 4434篇 |
2000年 | 3605篇 |
1999年 | 3308篇 |
1998年 | 2236篇 |
1997年 | 2007篇 |
1996年 | 2114篇 |
1995年 | 2114篇 |
1994年 | 1851篇 |
1993年 | 1689篇 |
1992年 | 1444篇 |
1991年 | 1262篇 |
1990年 | 1053篇 |
1989年 | 999篇 |
1988年 | 936篇 |
1987年 | 723篇 |
1986年 | 538篇 |
1985年 | 631篇 |
1984年 | 666篇 |
1983年 | 429篇 |
1982年 | 518篇 |
1981年 | 434篇 |
1980年 | 378篇 |
1979年 | 315篇 |
1978年 | 257篇 |
1977年 | 204篇 |
1976年 | 244篇 |
1975年 | 151篇 |
1974年 | 124篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
42.
43.
44.
45.
《Clinical neurophysiology》2021,132(2):315-322
ObjectivePrevious studies have demonstrated voluntary movement alterations as well as motor cortex excitability and plasticity changes in patients with mild cognitive impairment (MCI). To investigate the pathophysiology of movement abnormalities in MCI, we tested possible relationships between movement abnormalities and primary motor cortex alterations in patients.MethodsFourteen amnestic MCI (aMCI) patients and 16 healthy controls were studied. Cognitive assessment was performed using clinical scales. Finger tapping was recorded by a motion analysis system. Transcranial magnetic stimulation was used to test the input/output curve of motor evoked potentials, intracortical inhibition, and short-latency afferent inhibition. Primary motor cortex plasticity was probed by theta burst stimulation. We investigated correlations between movement abnormalities, clinical scores, and cortical neurophysiological parameters.ResultsMCI patients showed less rhythmic movement but no other movement abnormalities. Cortical excitability measures were normal in patients, whereas plasticity was reduced. Movement rhythm abnormalities correlated with frontal dysfunction scores.ConclusionOur study in MCI patients demonstrated abnormal voluntary movement and plasticity changes, with no correlation between the two. Altered rhythm correlated with frontal dysfunction.SignificanceOur results contribute to the understanding of pathophysiological mechanisms of motor impairment in MCI. 相似文献
46.
《Diagnostic and interventional imaging》2021,102(10):629-639
PurposeTo investigate the reproducibility of diffusion-weighted (DW) MRI and 18F-Fluorodeoxyglucose (18F-FDG)-Positron emission tomography/CT (PET/CT) in monitoring response to neoadjuvant chemotherapy in epithelial ovarian cancer.Materials and methodsTen women (median age, 67 years; range: 41.8–77.3 years) with stage IIIC-IV epithelial ovarian cancers were included in this prospective trial (NCT02792959) between 2014 and 2016. All underwent initial laparoscopic staging, four cycles of carboplatine-paclitaxel-based chemotherapy and interval debulking surgery. PET/CT and DW-MRI were performed at baseline (C0), after one cycle (C1) and before surgery (C4). Two nuclear physicians and two radiologists assessed five anatomic sites for the presence of ≥ 1 lesion. Target lesions in each site were defined and their apparent diffusion coefficient (ADC), maximal standardized uptake value (SUV-max), SUV-mean, SUL-peak, metabolic tumor volume (MTV) and total lesion glycolysis (TLG) were monitored (i.e., 10 patients × 5 sites × 3 time-points). Their relative early and late changes were calculated. Intra/inter-observer reproducibilities of qualitative and quantitative analysis were estimated with Kappa and intra-class correlation coefficients (ICCs).ResultsFor both modalities, inter- and intra-observer agreement percentages were excellent for initial staging but declined later for DW-MRI, leading to lower Kappa values for inter- and intra-observer variability (0.949 and 1 at C0, vs. 0.633 and 0.643 at C4, respectively) while Kappa values remained > 0.8 for PET/CT. Inter- and intra-observer ICCs were > 0.75 for SUV-max, SUL-peak, SUV-mean and their change regardless the time-point. ADC showed lower ICCs (range: 0.013–0.811). ANOVA found significant influences of the evaluation time, the measurement used (ADC, SUV-max, SUV-mean, SUV-max, SUL-peak, MTV or TLG) and their interaction on ICC values (P = 0.0023, P< 0.0001 and P =0.0028, respectively).ConclusionWhile both modalities demonstrated high reproducibility at baseline, only SUV-max, SUL-peak, SUV-mean and their changes maintained high reproducibility during chemotherapy. 相似文献
47.
目的采用Meta分析方法评价18F-脱氧葡萄糖正电子发射计算机体层摄影(18F-FDG PET/CT)和增强CT(CECT)诊断经导管肝动脉化疗栓塞术(TACE)术后存活或复发病灶的临床价值。方法根据PRISMA报告规范开展Meta分析。检索PubMed、Embase、Cochrane Library、Web of Science、中国知网、万方和维普数据库中18F-FDG PET/CT和CECT诊断TACE术后存活或复发病灶的临床研究,时间至2019-04。由2位研究人员独立筛选文献、提取资料,根据诊断准确性研究质量评价工具-2(QUADAS-2)评价纳入研究的偏倚风险后,采用Stata 12.0软件进行Meta分析,计算其汇总敏感度(Sen)和特异度(Spe),绘制受试者工作特征曲线(SROC)并计算曲线下面积(AUC)。结果共纳入10篇18F-FDG PET/CT及13篇CECT诊断TACE术后存活或复发病灶的原始研究,分别包括322例患者的467个病灶和748例患者的943个病灶。Meta分析显示,18F-FDG PET/CT诊断TACE术后存活或复发病灶的Sen=0.92(95%CI为0.87~0.94)、Spe=0.95(95%CI为0.82~0.99)、AUC=0.97(95%CI为0.93~0.99);CECT诊断TACE术后存活或复发病灶的Sen=0.72(95%CI为0.66~0.78)、Spe=0.99(95%CI为0.93~1.00)、AUC=0.87(95%CI为0.83~0.89)。此外,CECT诊断TACE术后存活或复发Sen(Z=2.34,P=0.02)和AUC(Z=2.21,P=0.03)值低于18F-FDG PET/CT,差异有统计学意义。结论相比于CECT,18F-FDG PET/CT对TACE术后存活或复发病灶具有较高诊断效能,可视为TACE术后存活或复发病灶有效的影像学诊断方法。 相似文献
48.
49.
目的 评估检测大肠肿瘤患者粪便中SEPT-9和微RNA(miRNA)-34b/c基因甲基化对大肠肿瘤筛查的临床性能。方法 采用病例对照研究方法,使用甲基化敏感性高分辨率熔解曲线法检测大肠肿瘤患者(大肠癌组35例、大肠腺瘤组47例)和正常对照人群(正常对照组52名)粪便中SEPT-9和miRNA-34b/c基因是否存在甲基化,来评估其筛查大肠肿瘤的性能。结果 大肠癌组SEPT-9和miRNA-34b/c基因的甲基化阳性率分别为68.6%、71.4%,大肠腺瘤组分别为57.4%、63.8%,正常对照组分别为9.6%、11.5%。3组的SEPT-9、miRNA-34b/c基因甲基化阳性率比较差异均有统计学意义(2SEPT-9 = 37.185,2miRNA-34b/c = 40.040,P均< 0.001),利用Bonferroni法进行两两比较,大肠癌组和大肠腺瘤组的甲基化阳性率比较差异无统计学意义,两者与正常对照组比较差异均有统计学意义(P均< 0.001)。3组联合检测SEPT-9和miRNA-34b/c基因的甲基化阳性率为88.6%、76.6%、13.5%,大肠癌组和大肠腺瘤组联合检测的甲基化阳性率均高于SEPT-9单基因检测和miRNA-34b/c单基因检测(P均< 0.05)。结论 检测粪便中SEPT-9和miRNA-34b/c基因甲基化具有效好的大肠肿瘤筛查性能,或许可作为大规模人群筛查大肠肿瘤新的生物标志物组合;多基因甲基化联合检测筛查的性能优于单基因。 相似文献
50.