全文获取类型
收费全文 | 4150篇 |
免费 | 353篇 |
专业分类
4503篇 |
出版年
2023年 | 49篇 |
2022年 | 101篇 |
2021年 | 154篇 |
2020年 | 118篇 |
2019年 | 121篇 |
2018年 | 100篇 |
2017年 | 98篇 |
2016年 | 165篇 |
2015年 | 315篇 |
2014年 | 311篇 |
2013年 | 286篇 |
2012年 | 375篇 |
2011年 | 385篇 |
2010年 | 200篇 |
2009年 | 134篇 |
2008年 | 196篇 |
2007年 | 169篇 |
2006年 | 160篇 |
2005年 | 139篇 |
2004年 | 90篇 |
2003年 | 75篇 |
2002年 | 87篇 |
2001年 | 45篇 |
2000年 | 35篇 |
1999年 | 41篇 |
1998年 | 25篇 |
1997年 | 25篇 |
1995年 | 16篇 |
1994年 | 10篇 |
1993年 | 16篇 |
1992年 | 12篇 |
1991年 | 26篇 |
1990年 | 16篇 |
1989年 | 12篇 |
1987年 | 11篇 |
1986年 | 17篇 |
1985年 | 16篇 |
1984年 | 15篇 |
1982年 | 12篇 |
1981年 | 12篇 |
1980年 | 14篇 |
1979年 | 11篇 |
1977年 | 12篇 |
1976年 | 12篇 |
1975年 | 10篇 |
1973年 | 19篇 |
1972年 | 10篇 |
1970年 | 13篇 |
1960年 | 9篇 |
1954年 | 9篇 |
排序方式: 共有4503条查询结果,搜索用时 15 毫秒
21.
The effects of 19-hydroxy-prostaglandins (19-OH-PGs) were tested on the rabbit oviduct and uterus and on the rhesus monkey () uterus. The 19-OH-PGEs suppressed spontaneous oviductal and uterine activity in the rabbit. The qualitative effect on the rabbit oviduct of 19-OH-PGEs was similar to that of PGE2. However, the typical response of the rabbit uterus to PGE2 was an increase in muscle activity. With regard to the rabbit oviduct, 19(R)-OH-PGE2 was as potent as PGE2, but 19(S)-OH-PGE2 was approximately as potent as PGE2. Based on the dose of 19-OH-PGEs usually required to cause a minimal suppression and the dose of PGE2 required to cause a minimal stimulation of rabbit uterine activity, 19(R)-OH-PGE2 was twice as potent as PGE2 while 19(S)-OH-PGE2 was as potent as PGE2. Stimulatory effects on the rabbit oviduct and uterus were observed following administration of 19-OH-PGEs and PGF2α. The potency on the rabbit oviduct of 19(S)-OH-PGF2α was about to that of PGF2α; the potency of 19(R)-OH-PGF2α was about to that of PGF2α. Both 19-OH-PGFs were approximately to as potent as PGF2α on the rabbit uterus. At the doses tested 19-OH-PGFs were inactive on the monkey uterus. Thus, these compounds are at least as active as PGF2α. In contrast, 19(R)-OH-PGE2 had approximately the same potency as PGE2 in stimulating monkey uterine activity; but 19(S)-OH-PGE2 was approximately as potent as PGE2. 相似文献
22.
R Keays P M Harrison J A Wendon A Forbes C Gove G J Alexander R Williams 《BMJ (Clinical research ed.)》1991,303(6809):1026-1029
OBJECTIVE--To see whether intravenous acetylcysteine would improve outcome in patients with fulminant hepatic failure after paracetamol overdose. DESIGN--A prospective randomised controlled study. SETTING--The Institute of Liver Studies, King''s College Hospital, London. PATIENTS--50 consecutive patients (21 male) aged 16-60 with fulminant hepatic failure after paracetamol overdose who had not previously received acetylcysteine. INTERVENTIONS--Conventional intensive liver care plus either acetylcysteine (25 patients) in the same dose regimen as used early after a paracetamol overdose, except that the infusion was continued until recovery from encephalopathy or death, or an equivalent volume of 5% dextrose (25 patients). MAIN OUTCOME MEASURES--Survival; incidence of cerebral oedema, renal failure, and hypotension requiring inotropic support; liver function as assessed by prolongation of the prothrombin time; and degree of encephalopathy. RESULTS--The rate of survival was significantly higher in the acetylcysteine treated group than in the controls (48% (12/25 patients) v 20% (5/25); p = 0.037, 95% confidence interval for difference in proportions surviving 3% to 53%). Acetylcysteine treated patients had a lower incidence of cerebral oedema (40% (10/25) v 68% (17/25); p = 0.047, 95% confidence interval for difference in incidence 2% to 54%), and fewer developed hypotension requiring inotropic support (48% (12/25) v 80% (20/25); p = 0.018, 95% confidence interval 7% to 57%). Rates of deterioration and recovery of liver function, however, were similar in the two groups. No adverse reactions to acetylcysteine were seen. CONCLUSIONS--Acetylcysteine is safe and effective in fulminant hepatic failure after paracetamol overdose. 相似文献
23.
24.
25.
26.
Collier-Hyams LS Sloane V Batten BC Neish AS 《Journal of immunology (Baltimore, Md. : 1950)》2005,175(7):4194-4198
The human enteric flora plays a significant role in intestinal health and disease. Certain enteric bacteria can inhibit the NF-kappaB pathway by blockade of IkappaB-alpha ubiquitination. IkappaB-alpha ubiquitination is catalyzed by the E3-SCF(betaTrCP) ubiquitin ligase, which is itself regulated via covalent modification of the cullin-1 subunit by the ubiquitin-like protein NEDD8. Neddylation is a biochemical event associated with diverse cellular processes related to cell signaling, however, physiological regulation of cullin neddylation has not been described in mammalian systems. We report that interaction of nonpathogenic bacteria with epithelial cells resulted in a rapid loss of neddylated Cul-1 and consequent repression of the NF-kappaB pathway. This observation may explain the ability of intestinal bacterial communities to influence diverse eukaryotic processes in general and inflammatory tolerance of the mammalian intestinal epithelia specifically. 相似文献
27.
Lauren Vogel 《CMAJ》2011,183(5):E261-E262
28.
29.
30.