全文获取类型
收费全文 | 4716篇 |
免费 | 215篇 |
国内免费 | 35篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 71篇 |
妇产科学 | 21篇 |
基础医学 | 783篇 |
口腔科学 | 8篇 |
临床医学 | 480篇 |
内科学 | 1376篇 |
皮肤病学 | 9篇 |
神经病学 | 299篇 |
特种医学 | 339篇 |
外科学 | 96篇 |
综合类 | 534篇 |
预防医学 | 444篇 |
眼科学 | 2篇 |
药学 | 359篇 |
2篇 | |
中国医学 | 80篇 |
肿瘤学 | 61篇 |
出版年
2024年 | 3篇 |
2023年 | 23篇 |
2022年 | 59篇 |
2021年 | 94篇 |
2020年 | 71篇 |
2019年 | 99篇 |
2018年 | 182篇 |
2017年 | 100篇 |
2016年 | 89篇 |
2015年 | 115篇 |
2014年 | 318篇 |
2013年 | 307篇 |
2012年 | 221篇 |
2011年 | 293篇 |
2010年 | 272篇 |
2009年 | 213篇 |
2008年 | 298篇 |
2007年 | 243篇 |
2006年 | 218篇 |
2005年 | 196篇 |
2004年 | 158篇 |
2003年 | 130篇 |
2002年 | 148篇 |
2001年 | 109篇 |
2000年 | 95篇 |
1999年 | 90篇 |
1998年 | 77篇 |
1997年 | 102篇 |
1996年 | 86篇 |
1995年 | 73篇 |
1994年 | 70篇 |
1993年 | 39篇 |
1992年 | 47篇 |
1991年 | 30篇 |
1990年 | 42篇 |
1989年 | 32篇 |
1988年 | 23篇 |
1987年 | 20篇 |
1986年 | 30篇 |
1985年 | 37篇 |
1984年 | 24篇 |
1983年 | 16篇 |
1982年 | 17篇 |
1981年 | 15篇 |
1980年 | 6篇 |
1979年 | 10篇 |
1978年 | 9篇 |
1977年 | 5篇 |
1976年 | 3篇 |
1975年 | 3篇 |
排序方式: 共有4966条查询结果,搜索用时 22 毫秒
1.
2.
3.
Stephan E. Maier Harvey E. Cline Ferenc A. Jolesz 《Magnetic resonance in medicine》1995,34(5):706-712
Three dimensional (3D) phase contrast angiograms contain velocity data, which is discarded after the reconstruction of the projections. In extension to earlier work on velocity quantification with ungated 2D phase data, this paper shows that a useful estimate of the average velocity and flow rate can be extracted from ungated 3D phase contrast angiograms. Simulations and experiments in a phantom and in vivo were performed. For pulsatile flow and strong spin saturation, an over-estimation of the flow rate at the net in-flow end of the imaging volume and underestimation at the net out-flow end was observed. Imaging at lower RF tip angles yielded flow rates close to the correct value within the entire imaging volume. In contrast to ungated 2D experiments, the flow rates determined by repeated 3D experiments showed no variation. 相似文献
4.
过度训练的病理生理及康复 Ⅰ.大鼠过度训练模型的建立 总被引:16,自引:1,他引:15
实验表明,运用大鼠跑台运动,以心电图、体重、饮食量、精神状况、毛发脱落、尿蛋白、血清睾酮、皮质醇等为监测指标建立大鼠过度训练模型的方法是可行的。本文并首次模拟出大鼠运动性心律失常心电图。 相似文献
5.
Tetsuo Kida Yoshiaki Nishihira Toshiaki Wasaka Yukie Sakajiri Toshiki Tazoe 《Clinical neurophysiology》2004,115(10):2223-2230
OBJECTIVE: We investigated modulation of the short- and long-latency somatosensory evoked potentials (SEPs) in a forewarned reaction time task. METHODS: A pair of warning (auditory) and imperative stimuli (somatosensory) was presented with a 2 s interstimulus interval. In movement condition, subjects responded by grip movement with the ipsilateral hand to the somatosensory stimulation when the imperative stimulus was presented. In counting condition, they silently counted the number of imperative stimuli. The SEPs in response to the imperative stimuli were recorded. RESULTS: Frontal N30 and central N60 amplitudes were significantly smaller in the movement than in the counting or rest conditions. None of the short-latency components differed between the counting and rest conditions. In contrast to the short-latency components, P80 was significantly larger in the counting than in the rest condition, and showed a further increase from the counting to the movement condition. The N140 amplitude was significantly larger in the movement than the rest condition, but was not changed between the counting and the rest conditions. CONCLUSIONS: The attenuation of the frontal N30 and central N60, and the enhancement of the P80 and possibly the N140 resulted from the centrifugal mechanism. The present findings may show the different effects of voluntary movement on the early and subsequent cortical processing of the relevant somatosensory information requiring a behavioral response. SIGNIFICANCE: The present study demonstrated the differential modulation of short- and long-latency components of SEPs in a forewarned reaction time task. 相似文献
6.
A recent series of randomized prospective clinical trials that compared rate control with rhythm control in patients with atrial fibrillation (AF) found no significant difference in primary outcome between the two strategies. However, these trials lacked clear criteria for defining "successful" rate or rhythm control. Various measures have been used to gauge the success of antiarrhythmic drug therapy, including time to first recurrence of AF, any AF recurrence, AF burden, and a reduction in symptoms. Determining the success of antiarrhythmic therapy can be relatively straightforward by using how patients feel during therapy as a key endpoint. Most patients are satisfied with a major reduction in symptomatic AF episodes and can live comfortably with occasional episodes of AF. For those who are bothered by even infrequent, brief AF episodes, a treatment regimen that eliminates nearly all AF recurrences is required, although often hard to achieve. Catheter ablation may be necessary to achieve a successful outcome in these patients. Suppression of AF in a patient at high risk of stroke does not, however, remove the need for concomitant warfarin therapy. The endpoints of ventricular rate control are not clear, and the recently published rhythm versus rate control trials lacked standard criteria for judging acceptable rate control. One relatively simple method is to try and achieve a 24-hour heart rate that mimics expected normal sinus rhythm. It is important to achieve good rate control to minimize symptoms and the risk of tachycardia-mediated cardiomyopathy. 相似文献
7.
8.
Can Electrocardiographic Criteria Predict Adverse Cardiac Events and Positive Cardiac Markers? 总被引:5,自引:0,他引:5
Andra L. Blomkalns MD Christopher J. Lindsell PhD Abhinav Chandra MD Mary E. Osterlund MD W. Brian Gibler MD Charles V. Pollack MS MD Brian R. Tiffany MD PhD Judd E. Hollander MD James W. Hoekstra MD 《Academic emergency medicine》2003,10(3):205-210
OBJECTIVES: To determine electrocardiogram (ECG) predictors of positive cardiac markers and short-term adverse cardiac events in an undifferentiated chest pain population presenting to emergency departments (EDs). The authors hypothesized that specific ECG findings, other than those previously identified in higher-risk populations, would be predictive of cardiac outcomes and positive cardiac markers. METHODS: This study used data from a prospectively collected, retrospectively analyzed Internet-based data registry of undifferentiated chest pain patients (i*trACS). Logistic regression modeling was performed to determine the ECG findings that were predictive of 1) positive cardiac markers and 2) short-term adverse cardiac events. RESULTS: ST-segment elevation (STE), ST-segment depression (STD), pathological Q-waves (PQW), and T-wave inversion were associated with increased odds of percutaneous coronary intervention or catheterization, myocardial infarction, or coronary artery bypass grafting. The odds of creatine kinase-MB (CK-MB) measuring positive were increased if STE, STD, or PQW were present [odds ratio (OR) 2.495, 2.582, and 1.295, respectively]. A right bundle branch block tended to decrease the odds of CK-MB measuring positive (OR 0.658). A similar pattern of results was observed for troponin I (OR 3.608 for STE, 3.72 for STD, 1.538 for PQW). Troponin T showed an increased odds of measuring positive if any of STE, STD, left bundle branch block, or T-wave inversion were evident (OR 2.313, 2.816, 1.80, and 1.449, respectively). CONCLUSIONS: Initial ECG criteria can be used to predict short-term cardiac outcomes and positive cardiac markers. These findings can be important aids in the risk-stratification and aggressive treatment regimens of chest pain patients presenting to EDs. 相似文献
9.
10.