收费全文 | 655篇 |
免费 | 103篇 |
国内免费 | 50篇 |
耳鼻咽喉 | 1篇 |
儿科学 | 11篇 |
妇产科学 | 3篇 |
基础医学 | 122篇 |
口腔科学 | 8篇 |
临床医学 | 60篇 |
内科学 | 149篇 |
皮肤病学 | 5篇 |
神经病学 | 24篇 |
特种医学 | 33篇 |
外科学 | 287篇 |
综合类 | 26篇 |
一般理论 | 1篇 |
预防医学 | 17篇 |
眼科学 | 5篇 |
药学 | 33篇 |
肿瘤学 | 23篇 |
2021年 | 16篇 |
2020年 | 9篇 |
2019年 | 13篇 |
2018年 | 23篇 |
2017年 | 11篇 |
2016年 | 12篇 |
2015年 | 20篇 |
2014年 | 13篇 |
2013年 | 28篇 |
2012年 | 26篇 |
2011年 | 47篇 |
2010年 | 34篇 |
2009年 | 40篇 |
2008年 | 51篇 |
2007年 | 31篇 |
2006年 | 20篇 |
2005年 | 25篇 |
2004年 | 22篇 |
2003年 | 24篇 |
2002年 | 26篇 |
2001年 | 19篇 |
2000年 | 28篇 |
1999年 | 17篇 |
1998年 | 14篇 |
1997年 | 15篇 |
1996年 | 19篇 |
1995年 | 6篇 |
1994年 | 9篇 |
1993年 | 17篇 |
1992年 | 13篇 |
1991年 | 12篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1982年 | 4篇 |
1981年 | 7篇 |
1977年 | 4篇 |
1966年 | 4篇 |
1963年 | 5篇 |
1962年 | 3篇 |
1932年 | 7篇 |
1931年 | 3篇 |
1930年 | 3篇 |
1929年 | 6篇 |
1928年 | 3篇 |
1927年 | 5篇 |
1925年 | 9篇 |
Methods: Barbiturate-anesthetized rats (n = 131) were instrumented for measurement of hemodynamics and subjected to a 30 min coronary artery occlusion followed by 2 h of reperfusion. Myocardial infarct size was determined using triphenyltetrazolium staining. Rats were randomly assigned to receive 0.9% saline, isoflurane (0.5 and 1.0 minimum alveolar concentration [MAC]), morphine (0.1 and 0.3 mg/kg), or morphine (0.3 mg/kg) plus isoflurane (1.0 MAC). Isoflurane was administered for 30 min and discontinued 15 min before coronary occlusion. In eight additional groups of experiments, rats received 5-hydroxydecanoic acid (5-HD; 10 mg/kg) or naloxone (6 mg/kg) in the presence or absence of isoflurane, morphine, and morphine plus isoflurane.
Results: Isoflurane (1.0 MAC) and morphine (0.3 mg/kg) reduced infarct size (41 +/- 3%; n = 13 and 38 +/- 2% of the area at risk; n = 10, respectively) as compared to control experiments (59 +/- 2%; n = 10). Morphine plus isoflurane further decreased infarct size to 26 +/- 3% (n = 11). 5-HD and naloxone alone did not affect infarct size, but abolished cardioprotection produced by isoflurane, morphine, and morphine plus isoflurane. 相似文献
Methods: Dogs (n = 8) were fitted with instruments for long-term measurement of LV and aortic blood pressure, aortic blood flow, and subendocardial segment length and received dexmedetomidine (1.25, 2.5, and 5 [micro sign]g/kg) in a cumulative manner before and after 19 +/- 3 (mean +/- SEM) days of rapid LV pacing. LV afterload was measured with aortic input impedance [Zin ([Greek small letter omega]) and quantified with a three-element Windkessel model. Hemodynamics and Zin ([Greek small letter omega]) were assessed under control conditions and 5 and 60 min after administration of each dose.
Results: Dexmedetomidine caused early and late decreases in heart rate, the maximum rate of increase of LV pressure, mean aortic blood flow, and stroke volume in dogs before and after pacing. Dexmedetomidine caused similar early increases in total arterial resistance and decreases in total arterial compliance in dogs before and after pacing. Early dexmedetomidine-induced increases in resistance and decreases in compliance caused similar reductions in mean aortic blood flow in cardiomyopathic compared with healthy dogs. Resistance and compliance returned to control values, and characteristic aortic impedance decreased late after dexmedetomidine in healthy dogs. In contrast, resistance remained elevated late after dexmedetomidine in dogs with dilated cardiomyopathy. 相似文献