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   278927篇
  免费   15866篇
  国内免费   6963篇
耳鼻咽喉   3049篇
儿科学   9495篇
妇产科学   3783篇
基础医学   21623篇
口腔科学   4789篇
临床医学   31896篇
内科学   47275篇
皮肤病学   3675篇
神经病学   13045篇
特种医学   13488篇
外国民族医学   22篇
外科学   38344篇
综合类   33247篇
现状与发展   27篇
一般理论   20篇
预防医学   27453篇
眼科学   4833篇
药学   26811篇
  156篇
中国医学   6237篇
肿瘤学   12488篇
  2023年   2604篇
  2022年   9503篇
  2021年   12116篇
  2020年   6965篇
  2019年   13331篇
  2018年   8466篇
  2017年   6838篇
  2016年   8239篇
  2015年   11259篇
  2014年   21418篇
  2013年   19006篇
  2012年   22274篇
  2011年   19225篇
  2010年   17303篇
  2009年   16523篇
  2008年   15052篇
  2007年   14743篇
  2006年   12559篇
  2005年   8325篇
  2004年   4464篇
  2003年   3886篇
  2002年   3037篇
  2001年   2413篇
  2000年   2185篇
  1999年   1419篇
  1998年   1823篇
  1997年   1654篇
  1996年   1337篇
  1995年   1363篇
  1994年   1298篇
  1993年   965篇
  1992年   1161篇
  1991年   1056篇
  1990年   1077篇
  1989年   1044篇
  1988年   968篇
  1987年   854篇
  1985年   2378篇
  1984年   3017篇
  1983年   2268篇
  1982年   2347篇
  1981年   2343篇
  1980年   2027篇
  1979年   1720篇
  1978年   1354篇
  1977年   1169篇
  1976年   1229篇
  1975年   923篇
  1974年   877篇
  1973年   823篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
221.
222.
《Clinical neurophysiology》2019,130(2):297-302
ObjectiveTo assess the diagnostic performance of electrophysiology and nerve ultrasound in ulnar neuropathies of varying clinical severity in 135 consecutive patients.MethodsClinical severity of ulnar neuropathy was graded on a 4 point scale from very mild (symptoms only) to severe (marked atrophy of intrinsic hand muscles). Sensitivity and localization ability of electrophysiology and nerve ultrasound were assessed for each point of the scale.ResultsUltrasound had higher sensitivity than electrophysiology in clinically very mild (20% and 3% for ultrasound and electrophysiology, respectively) and mild (62% and 47% for ultrasound and electrophysiology, respectively) neuropathies, had greater localizing ability in axonal ulnar neuropathies, and identified nerve hypermobility.Ultrasound nerve cross-sectional area had strong positive correlation with both clinical and electrophysiological severity scores, but with significant overlap across the severity groups.ConclusionThe diagnostic work-up of ulnar neuropathies was improved by using both electrophysiology and ultrasound at all levels of clinical severity. Ultrasound increased the diagnostic yield in very mild and mild neuropathies, localized all the ulnar neuropathies with abnormal non-localizing electrophysiology and identified nerve hypermobility.SignificanceThis is the first detailed analysis of the diagnostic performance of electrophysiology and ultrasound in ulnar neuropathies of varying severity.  相似文献   
223.
224.
225.
226.
ObjectiveMultiple treatment options for acetabular fractures in geriatric patients exist. However, no large-scale studies have reported the outcomes of acute total hip arthroplasty (THA) in this patient population. We systematically evaluated all available evidence to characterize clinical outcomes, complications, and revisions of acute THA for acetabular fractures in geriatric patients.MethodsMeta-analysis of 21 studies of 430 acetabular fractures with mean follow-up of 44 months (range, 17−97 months). Two independent researchers searched and evaluated the databases of Ovid, Embase, and United States National Library of Medicine using a Boolean search string up to December 2019. Population demographics and complications, including presence of heterotopic ossification (HO), dislocation, infection, revision rate, neurological deficits, and venous thromboembolic event (VTE), were recorded and analyzed.ResultsWeighted mean Harris Hip Score was 83.3 points, and 20% of the patients had reported complications. The most common complication was HO, with a rate of 19.5%. Brooker grade III and IV HO rates were lower at 6.8%. Hip dislocation occurred at a rate of 6.1%, 4.1% of patients developed VTE, deep infection occurred in 3.8%, and neurological complications occurred in 1.9%. Although the revision rate was described in most studies, we were unable to perform a survival analysis because the time to each revision was described in only a few studies. The revision rate was 4.3%.ConclusionsAcute THA is a viable option for treatment of acetabular fracture and can result in acceptable clinical outcomes and survivorship rates in older patients but with an associated complication rate of approximately 20%. Considering the limited treatment options, THA might be a viable alternative for appropriately selected patients.  相似文献   
227.
228.
地方志作为"地方性的百科全书",因其全面性而往往为专业研究如医学研究所忽略,而其中却不乏丰富的医学资料。通过对北京地方志中的医学资料进行挖掘,发现涉及太医院、官办医药机构、社会福利机构、医家、流行病、土产药物、药王庙等内容,并对相关文献进行分析,以展现北京地方志医学资料情况,为后期进一步研究奠定基础。  相似文献   
229.
ObjectivesEarly diagnosis of cognitive impairment is increasingly emphasized in the literature to facilitate timely preventive interventions. Although bedside cognitive tests such as the Montreal Cognitive Assessment (MoCA) are widely used for such early diagnostic purposes, they may not have comparable performance to a full neuropsychological battery (FNB) in diagnosing early cognitive impairment. This study investigated whether a small subset of neuropsychological tests can be added on to MoCA to match its performance to that of the FNB in discriminating mild cognitive impairment and dementia (MCI/dementia) from normal cognition.DesignCross-sectional diagnostic study.SettingAlzheimer's Disease Centers across the United States.ParticipantsOlder participants (≥50 years) who completed MoCA and the FNB (N = 9187).MeasuresThe study sample was split into two: the derivation sample (n = 1837) was used to develop a brief neuropsychological battery that best discriminated MCI/dementia (using the best-subset approach with 10-fold cross-validation); while the validation sample (n = 7350) verified its actual performance in discriminating MCI/dementia.ResultsA 3-item neuropsychological battery was identified, comprising MoCA, Benson Complex Figure Recall, and Craft Story 21 Delayed Recall. It had excellent performance in discriminating MCI/dementia from normal cognition (area under the receiver operating characteristic curve [AUROC] 90.0%, 95% confidence interval [CI] 89.2%-90.7%), which was comparable to that of the FNB (AUROC 88.4%, 95% CI 87.6%-89.2%). By contrast, MoCA alone had significantly worse AUROC (86.9%, 95% CI 86.0%-87.7%) than that of the FNB.Conclusions/ImplicationsUsing rigorous methods, this study developed a brief neuropsychological battery that maintained the brevity of a bedside cognitive test, while rivaling the diagnostic performance of an FNB in early cognitive impairment. This brief battery offers a viable alternative when the FNB is needed but cannot be feasibly administered in nonspecialty clinics. It can have a wider health systems effect of improving patients’ access to accurate diagnosis in early cognitive impairment and facilitating timely interventions to delay the progression of cognitive impairment.  相似文献   
230.
目的观察1.5T场强MRI联合动物专用线圈是否可以活体示踪经门静脉移植的纳米级超顺磁性氧化铁颗粒标记的骨髓基质细胞(bone marrow stromal cells BMSCs),为介人性门静脉骨髓基质细胞移植治疗终末期肝脏疾病的研究提供进一步的依据。方法供体大鼠5只,梯度密度离心分离BMSCs,纳米级超顺磁性氧化铁颗粒和脂质体转染BMSCs,体外经普鲁士蓝染色和HE染色确定细胞标记率。受体大鼠15只,分为5组,分别为对照组和纳米级超顺磁性氧化铁颗粒标记的骨髓基质细胞经门静脉移植人正常大鼠肝脏后2h、3d、7d及2周组。1.5T场强MRI联合动物专用线圈行T1W、T2W和T2*序列扫描,观察肝脏信号改变情况,与对照组比较,并且与组织切片对照。结果纳米级超顺磁性氧化铁颗粒和脂质体转染BMSCs,细胞标记率〉95%。经门静脉移植人正常大鼠肝脏后,T2*序列扫描显示经标记的BMSCs在肝内显示弥漫性的结节性低信号影,移植后2h到2周均可见到细胞在受体肝脏内存在,组织学切片显示信号缺失部位与铁颗粒标记细胞相一致。结论纳米级超顺磁性铁氧体颗粒标记的大鼠BMSCs经门静脉移植后可以通过1、5T场强行MRI活体示踪,为临床干细胞移植的应用提供可行的示踪方法。  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