收费全文 | 2786篇 |
免费 | 113篇 |
国内免费 | 31篇 |
耳鼻咽喉 | 18篇 |
儿科学 | 33篇 |
妇产科学 | 60篇 |
基础医学 | 332篇 |
口腔科学 | 27篇 |
临床医学 | 313篇 |
内科学 | 734篇 |
皮肤病学 | 54篇 |
神经病学 | 253篇 |
特种医学 | 113篇 |
外科学 | 384篇 |
综合类 | 7篇 |
一般理论 | 2篇 |
预防医学 | 119篇 |
眼科学 | 13篇 |
药学 | 242篇 |
中国医学 | 2篇 |
肿瘤学 | 224篇 |
2024年 | 3篇 |
2023年 | 9篇 |
2022年 | 30篇 |
2021年 | 55篇 |
2020年 | 26篇 |
2019年 | 30篇 |
2018年 | 52篇 |
2017年 | 40篇 |
2016年 | 36篇 |
2015年 | 56篇 |
2014年 | 73篇 |
2013年 | 100篇 |
2012年 | 223篇 |
2011年 | 229篇 |
2010年 | 105篇 |
2009年 | 104篇 |
2008年 | 218篇 |
2007年 | 240篇 |
2006年 | 191篇 |
2005年 | 205篇 |
2004年 | 212篇 |
2003年 | 195篇 |
2002年 | 168篇 |
2001年 | 19篇 |
2000年 | 11篇 |
1999年 | 25篇 |
1998年 | 47篇 |
1997年 | 38篇 |
1996年 | 27篇 |
1995年 | 33篇 |
1994年 | 22篇 |
1993年 | 12篇 |
1992年 | 10篇 |
1991年 | 12篇 |
1990年 | 11篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 8篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 8篇 |
1978年 | 2篇 |
1977年 | 1篇 |
Methods: The effects of desflurane (1.8 to 9.4 vol%) in left ventricular papillary muscles of healthy hamsters and those with genetically induced cardiomyopathy (strain BIO 14.6) were investigated in vitro (29 [degree sign]C, pH 7.40, Ca2+ 2.5 mM; stimulation frequency, 3/min) under low (isotony) and high (isometry) load. Data are mean percentages of baseline +/- SD.
Results: Desflurane induced no significant inotropic effect in healthy muscles (maximum unloaded shortening velocity and isometric active force at 9.4 vol%: 97 +/- 9% and 92 +/- 20%, respectively). In contrast, in cardiomyopathic muscles, desflurane induced a moderate negative inotropic effect (maximum unloaded shortening velocity and active force at 9.4 vol%: 84 +/- 19% and 75 +/- 25%, respectively). The negative inotropic effect was more pronounced than that in healthy muscles under low (P < 0.05) but not high load, and even when concentrations were corrected for minimum alveolar concentrations in each strain. Adrenoceptor blockade or pretreatment with reserpine did not modify the inotropic effect of desflurane, suggesting the absence of intramyocardial catecholamine release. However, tyramine also did not induce any significant catecholamine release in hamster myocardium. In both strains, desflurane induced no significant lusitropic effect under low or high load. 相似文献
Methods: Ninety-eight parturient requesting labor analgesia were studied. In a combined spinal-epidural technique, patients were randomly assigned to receive one of the following intrathecal solutions: either 15 micro gram clonidine (n = 10); 30 micro gram clonidine (n = 10); 2.5 micro gram sufentanil (n = 13); 5 micro gram sufentanil (n = 13); 2.5 micro gram sufentanil and 15 micro gram clonidine (n = 13); 2.5 micro gram sufentanil and 30 micro gram clonidine (n = 13); 5 micro gram sufentanil and 15 micro gram clonidine (n = 13); or 5 micro gram sufentanil and 30 micro gram clonidine (n = 13). Visual analog scores for pain, blood pressure, heart rate, sensory levels, incidence of nausea and pruritus, and motor blockade, and maternal and cord blood concentrations of clonidine were recorded.
Results: Patients receiving 30 micro gram intrathecal clonidine with 2.5 or 5 micro gram intrathecal sufentanil had significantly longer-lasting analgesia (145 +/- 36 and 145 +/- 43 min vs. 104 +/- 35 for those receiving 5 micro gram intrathecal sufentanil alone). Clonidine levels were undetectable in maternal serum. 相似文献
Methods: Consecutive patients (n = 202) were included and divided into two groups according to the postoperative value of cTnI (< or >= 13 ng/ml). In-hospital mortality and nonfatal cardiac events (delayed extubation > 24 h; postoperative requirement of inotropic agent; ventricular and supraventricular arrhythmia; postoperative myocardial infarction) were recorded. Survivors were then followed up over a 2-yr period. Data are median and odds ratio (95% confidence interval).
Results: Of all patients, 174 (86%) had a low cTnI (4.1 ng/ml; range, 1.1-12.6) and 28 (14%) had a high cTnI (23.8 ng/ml; range, 13.4-174.6). In-hospital mortality was not significantly different (4 vs. 2%), whereas long-term mortality (18 vs. 3%, P = 0.006) and mortality from cardiac cause (18 vs. 1%, P < 0.001) was greater in patients with a high cTnI. A high cTnI was a significant factor predicting death (odds ratio, 7.3 [2.0-27.1]) or death from cardiac causes (odds ratio, 37.4 [4.2-334.4]). Nonfatal cardiac events were also more frequent in the hospital (64 vs. 41%, P = 0.02) and within the 2-yr follow-up period (39%vs. 16%, P = 0.03) in patients with high cTnI. 相似文献