收费全文 | 6159篇 |
免费 | 611篇 |
国内免费 | 25篇 |
耳鼻咽喉 | 107篇 |
儿科学 | 132篇 |
妇产科学 | 73篇 |
基础医学 | 850篇 |
口腔科学 | 98篇 |
临床医学 | 790篇 |
内科学 | 1205篇 |
皮肤病学 | 116篇 |
神经病学 | 550篇 |
特种医学 | 157篇 |
外科学 | 579篇 |
综合类 | 75篇 |
一般理论 | 1篇 |
预防医学 | 895篇 |
眼科学 | 241篇 |
药学 | 496篇 |
中国医学 | 24篇 |
肿瘤学 | 406篇 |
2023年 | 44篇 |
2022年 | 47篇 |
2021年 | 122篇 |
2020年 | 93篇 |
2019年 | 108篇 |
2018年 | 149篇 |
2017年 | 115篇 |
2016年 | 117篇 |
2015年 | 125篇 |
2014年 | 176篇 |
2013年 | 291篇 |
2012年 | 447篇 |
2011年 | 438篇 |
2010年 | 210篇 |
2009年 | 185篇 |
2008年 | 339篇 |
2007年 | 392篇 |
2006年 | 324篇 |
2005年 | 358篇 |
2004年 | 364篇 |
2003年 | 314篇 |
2002年 | 330篇 |
2001年 | 105篇 |
2000年 | 104篇 |
1999年 | 104篇 |
1998年 | 66篇 |
1997年 | 49篇 |
1996年 | 39篇 |
1995年 | 30篇 |
1994年 | 39篇 |
1993年 | 35篇 |
1992年 | 48篇 |
1991年 | 57篇 |
1990年 | 77篇 |
1989年 | 71篇 |
1988年 | 54篇 |
1987年 | 61篇 |
1986年 | 47篇 |
1985年 | 49篇 |
1984年 | 52篇 |
1983年 | 33篇 |
1982年 | 41篇 |
1980年 | 32篇 |
1979年 | 36篇 |
1978年 | 35篇 |
1973年 | 37篇 |
1972年 | 30篇 |
1971年 | 35篇 |
1970年 | 46篇 |
1968年 | 34篇 |
Background
The optimal noninvasive test (NIT) for patients with diabetes and stable symptoms of coronary artery disease (CAD) is unknown.Objectives
The purpose of this study was to assess whether a diagnostic strategy based on coronary computed tomographic angiography (CTA) is superior to functional stress testing in reducing adverse cardiovascular (CV) outcomes (CV death or myocardial infarction [MI]) among symptomatic patients with diabetes.Methods
PROMISE (Prospective Multicenter Imaging Study for Evaluation of Chest Pain) was a randomized trial evaluating an initial strategy of CTA versus functional testing in stable outpatients with symptoms suggestive of CAD. The study compared CV outcomes in patients with diabetes (n = 1,908 [21%]) and without diabetes (n = 7,058 [79%]) based on their randomization to CTA or functional testing.Results
Patients with diabetes (vs. without) were similar in age (median 61 years vs. 60 years) and sex (female 54% vs. 52%) but had a greater burden of CV comorbidities. Patients with diabetes who underwent CTA had a lower risk of CV death/MI compared with functional stress testing (CTA: 1.1% [10 of 936] vs. stress testing: 2.6% [25 of 972]; adjusted hazard ratio: 0.38; 95% confidence interval: 0.18 to 0.79; p = 0.01). There was no significant difference in nondiabetic patients (CTA: 1.4% [50 of 3,564] vs. stress testing: 1.3% [45 of 3,494]; adjusted hazard ratio: 1.03; 95% confidence interval: 0.69 to 1.54; p = 0.887; interaction term for diabetes p value = 0.02).Conclusions
In diabetic patients presenting with stable chest pain, a CTA strategy resulted in fewer adverse CV outcomes than a functional testing strategy. CTA may be considered as the initial diagnostic strategy in this subgroup. (PROspective Multicenter Imaging Study for Evaluation of Chest Pain [PROMISE]; NCT01174550) 相似文献Methods: Eight healthy volunteers received intrathecal injection of morphine (50 [mu]g) plus fentanyl (50 [mu]g) at a lower lumbar interspace. CSF was sampled through a needle in an upper lumbar interspace for 60-120 min. At the end of this time, a sample was taken from the lower lumbar needle, and both needles were withdrawn. CSF volume was determined by magnetic resonance imaging. Pharmacokinetic modeling was performed with NONMEM.
Results: Morphine and fentanyl peaked in CSF at the cephalad needle at similar times (41 +/- 13 min for fentanyl, 57 +/- 12 min for morphine). The ratio of morphine to fentanyl in CSF at the cephalad needle increased with time, surpassing 2:1 by 36 min and 4:1 by 103 min. CSF concentrations did not correlate with weight, height, or lumbosacral CSF volume. The concentrations of morphine and fentanyl at both sampling sites were well described by a simple pharmacokinetic model. The individual model parameters did not correlate with the distance between the needles, CSF volume, patient height, or patient weight. 相似文献