收费全文 | 8548篇 |
免费 | 625篇 |
国内免费 | 31篇 |
耳鼻咽喉 | 105篇 |
儿科学 | 213篇 |
妇产科学 | 241篇 |
基础医学 | 1272篇 |
口腔科学 | 153篇 |
临床医学 | 1036篇 |
内科学 | 1755篇 |
皮肤病学 | 199篇 |
神经病学 | 922篇 |
特种医学 | 265篇 |
外科学 | 840篇 |
综合类 | 70篇 |
一般理论 | 1篇 |
预防医学 | 765篇 |
眼科学 | 118篇 |
药学 | 560篇 |
中国医学 | 41篇 |
肿瘤学 | 648篇 |
2024年 | 11篇 |
2023年 | 98篇 |
2022年 | 207篇 |
2021年 | 377篇 |
2020年 | 252篇 |
2019年 | 263篇 |
2018年 | 300篇 |
2017年 | 224篇 |
2016年 | 282篇 |
2015年 | 324篇 |
2014年 | 368篇 |
2013年 | 502篇 |
2012年 | 730篇 |
2011年 | 740篇 |
2010年 | 416篇 |
2009年 | 368篇 |
2008年 | 572篇 |
2007年 | 506篇 |
2006年 | 492篇 |
2005年 | 479篇 |
2004年 | 401篇 |
2003年 | 347篇 |
2002年 | 340篇 |
2001年 | 45篇 |
2000年 | 33篇 |
1999年 | 38篇 |
1998年 | 71篇 |
1997年 | 42篇 |
1996年 | 35篇 |
1995年 | 33篇 |
1994年 | 33篇 |
1993年 | 21篇 |
1992年 | 15篇 |
1991年 | 13篇 |
1990年 | 13篇 |
1989年 | 14篇 |
1988年 | 18篇 |
1987年 | 9篇 |
1986年 | 6篇 |
1985年 | 8篇 |
1984年 | 15篇 |
1983年 | 12篇 |
1982年 | 19篇 |
1981年 | 6篇 |
1980年 | 9篇 |
1978年 | 11篇 |
1977年 | 6篇 |
1975年 | 10篇 |
1937年 | 5篇 |
1928年 | 5篇 |
Methods: For infarct size measurements, anesthetized rats were subjected to 25 min of coronary artery occlusion followed by 120 min of reperfusion. Rats received nitrous oxide (60%), isoflurane (1.4%) or isoflurane-nitrous oxide (1.4%/60%) during three 5-min periods before index ischemia (each group, n = 7). Control animals remained untreated for 45 min. Additional hearts (control, 60% nitrous oxide alone%, and isoflurane-nitrous oxide [0.6%/60%, in equianesthetic doses]) were excised for Western blot of PKC-[varepsilon] and Src kinase (each group, n = 4).
Results: Nitrous oxide had no effect on infarct size (59.1 +/- 15.2% of the area at risk vs. 51.1 +/- 10.9% in controls). Isoflurane (1.4%) and isoflurane-nitrous oxide (1.4%/60%) reduced infarct size to 30.9 +/- 10.6 and 28.7 +/- 11.8% (both P < 0.01). Nitrous oxide (60%) had no effect on phosphorylation (2.3 +/- 1.8 vs. 2.5 +/- 1.7 in controls, average light intensity, arbitrary units) and translocation (7.0 +/- 4.3 vs. 7.4 +/- 5.2 in controls) of PKC-[varepsilon]. Src kinase phosphorylation was not influenced by nitrous oxide (4.6 +/- 3.9 vs. 5.0 +/- 3.8; 3.2 +/- 2.2 vs. 3.5 +/- 3.0). Isoflurane-nitrous oxide (0.6%/60%, in equianesthetic doses) induced PKC-[varepsilon] phosphorylation (5.4 +/- 1.9 vs. 2.8 +/- 1.5; P < 0.001) and translocation to membrane regions (13.8 +/- 13.0 vs. 6.7 +/- 2.0 in controls; P < 0.05). 相似文献
Methods: Thirteen healthy male volunteers (aged 19-26 yr) were given placebo or 15, 22.5, or 30 mg/kg acetaminophen intravenously in a double-blind, crossover study. Ten and 90 min after infusion, platelet function was assessed by photometric aggregometry and by measuring release of thromboxane B2, analgesia by cold pressor test, and plasma acetaminophen concentrations by high-performance liquid chromatography.
Results: When triggered with 500 [mu]m arachidonic acid, median platelet aggregation (area under the curve) was 25.7, 22.8, 4.1, or 3.6 x 103 area units (P < 0.001) 10 min after placebo or 15, 22.5, or 30 mg/kg acetaminophen, respectively. An increasing concentration of arachidonic acid attenuated the antiaggregatory effect. After 90 min, platelet function was recovering. Release of thromboxane B2 was also dose-dependently inhibited by acetaminophen. Although plasma concentration of acetaminophen increased linearly with the dose, no analgesic effect was detected in the cold pressor test. 相似文献