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   61660篇
  免费   5462篇
  国内免费   2630篇
耳鼻咽喉   557篇
儿科学   1204篇
妇产科学   763篇
基础医学   5309篇
口腔科学   1883篇
临床医学   6995篇
内科学   10994篇
皮肤病学   1535篇
神经病学   3138篇
特种医学   2705篇
外国民族医学   10篇
外科学   5487篇
综合类   11368篇
现状与发展   16篇
一般理论   4篇
预防医学   5609篇
眼科学   2118篇
药学   5202篇
  35篇
中国医学   3077篇
肿瘤学   1743篇
  2024年   65篇
  2023年   1103篇
  2022年   1636篇
  2021年   2532篇
  2020年   2654篇
  2019年   2169篇
  2018年   2079篇
  2017年   1998篇
  2016年   2306篇
  2015年   2235篇
  2014年   4082篇
  2013年   4496篇
  2012年   3770篇
  2011年   4064篇
  2010年   3451篇
  2009年   3257篇
  2008年   3228篇
  2007年   3255篇
  2006年   2947篇
  2005年   2718篇
  2004年   2207篇
  2003年   1943篇
  2002年   1666篇
  2001年   1475篇
  2000年   1241篇
  1999年   908篇
  1998年   792篇
  1997年   650篇
  1996年   504篇
  1995年   605篇
  1994年   486篇
  1993年   352篇
  1992年   374篇
  1991年   356篇
  1990年   259篇
  1989年   260篇
  1988年   237篇
  1987年   234篇
  1986年   181篇
  1985年   183篇
  1984年   139篇
  1983年   86篇
  1982年   94篇
  1981年   100篇
  1980年   65篇
  1979年   74篇
  1978年   52篇
  1977年   47篇
  1976年   39篇
  1975年   30篇
排序方式: 共有10000条查询结果,搜索用时 20 毫秒
81.
PurposeTo investigate and compare venous sac and feeding artery embolization (VFE) with feeding artery embolization (FAE) alone for treatment of pulmonary arteriovenous malformations (PAVMs), based on difference in outcomes in decrease of the size of the draining vein.Materials and MethodsTwenty-six patients (7 male and 19 female; median age [interquartile range], 58 years [46–65 years]) with 42 simple PAVMs treated with coil embolization between August 2005 and December 2018 were retrospectively evaluated. Twenty PAVMs were treated with FAE early in the study period and compared with 22 PAVMs treated with VFE later in the study period. Follow-up computed tomography images obtained 8–20 months after embolotherapy were used for outcome analysis. Data related to patient demographics; follow-up period; baseline diameters of the feeding artery, venous sac, and draining vein; draining vein diameter after treatment; and decrease in the size of the draining vein, including the number reaching a threshold of 70% decrease, were compared between the 2 groups.ResultsThe draining vein decreased in size by a median of 46.4% in the FAE group and 66.3% in the VFE group, and the difference between the 2 groups was statistically significant (P = .009). There were no significant differences in the other parameters.ConclusionsVFE leads to a greater decrease in the size of the draining vein than FAE, suggesting that VFE results in more complete occlusion than FAE for treatment of PAVMs.  相似文献   
82.
《Brain stimulation》2021,14(4):927-937
BackgroundIncreases in the volume of the amygdala and hippocampus after electroconvulsive therapy (ECT) are among the most robust effects known to the brain-imaging field. Recent advances in the segmentation of substructures of these regions allow for novel insights on the relationship between brain structure and clinical outcomes of ECT.ObjectiveWe aimed to provide a comprehensive synthesis of evidence available on changes in brain structure after ECT, including recently published data on hippocampal subfields.MethodsA meta-analysis of published studies was carried out using random-effects models of standardized mean change of regional brain volumes measured with longitudinal magnetic resonance imaging of depressive patients before and after a series of ECT.ResultsData from 21 studies (543 depressed patients) were analysed, including 6 studies (118 patients) on hippocampal subfields. Meta-analyses could be carried out for seven brain regions for which data from at least three published studies was available. We observed increases in left and right hippocampi, amygdalae, cornua ammonis (CA) 1, CA 2/3, dentate gyri (DG) and subicula with standardized mean change scores ranging between 0.34 and 1.15. The model did not reveal significant volume increases in the caudate. Meta-regression indicated a negative relationship between the reported increases in the DG and relative symptom improvement (−0.27 (SE: 0.09) per 10%).ConclusionsECT is accompanied by significant volume increases in the bilateral hippocampus and amygdala that are not associated with treatment outcome. Among hippocampal subfields, the most robust volume increases after ECT were measured in the dentate gyrus. The indicated negative correlation of this effect with antidepressant efficacy warrants replication in data of individual patients.  相似文献   
83.
84.
Clostridioides (Clostridium) difficile (C. difficile) infection is one of the most common causes of increased morbidity and mortality. Approximately 500 000 C. difficile infections (CDIs) occur each year in the United States, and they result in more than 29 000 deaths. Patients with haematologic diseases are at a higher risk for this infection due to frequent hospitalization and exposure to treatment-associated risk factors. Whilst several currently available antimicrobial agents offer resolution, recurrence of infection remains a major concern. Recent advancement in deciphering C. difficile virulence mechanisms and identification of its allies in contributing to the infection has led to the development of alternative treatment strategies. Here, we will provide a contemporary discussion of how major risk factors in haematologic diseases, such as immunosuppression, chemoradiation, use of antibiotic, proton pump inhibitor and opioid, and deficiency in butyrate and antimicrobial peptides contribute to C. difficile infection. Next, we will highlight different approaches to control and mitigate this infection such as antibiotic stewardship and faecal microbiota transplantation. Finally, we will explore several emerging treatments such as use of pre- and probiotics, immunotherapy and microbiome-sparing agents.  相似文献   
85.
86.
《Brain stimulation》2021,14(4):837-847
BackgroundThe ubiquitous vascular response to transcranial electrical stimulation (tES) has been attributed to the secondary effect of neuronal activity forming the classic neurovascular coupling. However, the current density delivered transcranially concentrates in: A) the cerebrospinal fluid of subarachnoid space where cerebral vasculature resides after reaching the dural and pial surfaces and B) across the blood-brain-barrier after reaching the brain parenchyma. Therefore, it is anticipated that tES has a primary vascular influence.ObjectivesFocused review of studies that demonstrated the direct vascular response to electrical stimulation and studies demonstrating evidence for tES-induced vascular effect in coupled neurovascular systems.ResultstES induces both primary and secondary vascular phenomena originating from four cellular elements; the first two mediating a primary vascular phenomenon mainly in the form of an immediate vasodilatory response and the latter two leading to secondary vascular effects and as parts of classic neurovascular coupling: 1) The perivascular nerves of more superficially located dural and pial arteries and medium-sized arterioles with multilayered smooth muscle cells; and 2) The endothelial lining of all vessels including microvasculature of blood-brain barrier; 3) Astrocytes; and 4) Neurons of neurovascular units.ConclusionA primary vascular effect of tES is highly suggested based on various preclinical and clinical studies. We explain how the nature of vascular response can depend on vessel anatomy (size) and physiology and be controlled by stimulation waveform. Further studies are warranted to investigate the mechanisms underlying the vascular response and its contribution to neural activity in both healthy brain and pathological conditions – recognizing many brain diseases are associated with alteration of cerebral hemodynamics and decoupling of neurovascular units.  相似文献   
87.
目的探讨《临证指南医案》痹证用药特点。方法 运用数据挖掘技术统计药物使用频次、性味归经并进行关联规则、聚类、复杂网络分析等。结果 筛选出83首处方,共涉及中药125味,使用频次前5位依次为桂枝、茯苓、白术、当归、苦杏仁,功效类别以补虚药为主,性味以甘温最多,归经主要涉及肺、脾、肝、心、肾、胃;关联规则得到10对常见组合,高频中药聚为4类,复杂网络分析得到1个核心组合。结论 叶氏常从络病角度治痹,或通、或补、或通补皆施,重视肺脾,注重调和气血营卫,擅长通补奇经治法。  相似文献   
88.
89.
目的探讨番泻叶、聚乙二醇和二甲基硅油联合应用对于胶囊内镜(CE)检查可见度及检出率的影响。方法选取该院2016年6月-2018年9月拟行CE检查的患者126例,采用随机数表法分为对照组(n=62)与观察组(n=64),两组检查前禁食3 d,对照组予以聚乙二醇和二甲基硅油作为肠道准备,观察组在此基础上给予口服番泻叶。比较两组胃排空时间、小肠转运时间、胃和小肠的染色节段长度、绿色条带长度、肠道清洁程度、两组病变检出情况及不良反应发生情况。结果两组患者胃排空时间、小肠转运时间、胃和小肠的染色节段无明显差异(P0.05);观察组全小肠和远端小肠绿色条带长度短于对照组,差异均有统计学意义[(5.53±2.93) vs (6.74±2.76)cm;t=2.39,P=0.019;(3.37±2.04) vs (5.56±2.13)cm;t=5.90,P=0.000];两组近端小肠清洁程度差异无统计学意义(P0.05),观察组远端小肠(89.06%vs59.68%,χ2=14.35,P=0.000)和全小肠(87.50%vs 48.39%,χ2=22.23,P=0.000)清洁率明显高于对照组,差异有统计学意义;观察组病变总检出率明显高于对照组(92.18%vs 72.58%,χ2=8.40,P=0.004);两组不良反应发生率差异无统计学意义(17.74%vs 18.75%,P0.05)。结论添加番泻叶可有效提高聚乙二醇和二甲基硅油对于CE的检查可见度和检出率。  相似文献   
90.
骨强度不仅与骨密度(BMD)、骨微结构相关,还受骨髓微环境的影响。骨髓脂肪组织(MAT)与骨小梁、造血细胞、神经血管组织共同存在于骨髓腔中,对骨重建、骨髓造血、维持骨髓微环境的稳定起重要作用。近年研究表明,MAT可通过分泌脂联素等细胞因子参与介导代谢性疾病、血液系统肿瘤、癌症等疾病的发生发展,为疾病预防、治疗及监测提供了新的思路。本文拟对MAT生物学特性、影像学测量方法、MAT与疾病相关性及可能的作用机制予以综述。  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