全文获取类型
收费全文 | 536篇 |
免费 | 23篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 55篇 |
妇产科学 | 3篇 |
基础医学 | 62篇 |
口腔科学 | 11篇 |
临床医学 | 71篇 |
内科学 | 133篇 |
皮肤病学 | 21篇 |
神经病学 | 2篇 |
特种医学 | 139篇 |
外科学 | 14篇 |
综合类 | 9篇 |
预防医学 | 6篇 |
眼科学 | 4篇 |
药学 | 13篇 |
肿瘤学 | 16篇 |
出版年
2022年 | 2篇 |
2021年 | 5篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 6篇 |
2017年 | 1篇 |
2016年 | 4篇 |
2015年 | 9篇 |
2014年 | 9篇 |
2013年 | 14篇 |
2012年 | 6篇 |
2011年 | 10篇 |
2010年 | 23篇 |
2009年 | 19篇 |
2008年 | 8篇 |
2007年 | 5篇 |
2006年 | 10篇 |
2005年 | 7篇 |
2004年 | 4篇 |
2003年 | 8篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 35篇 |
1997年 | 46篇 |
1996年 | 45篇 |
1995年 | 36篇 |
1994年 | 19篇 |
1993年 | 22篇 |
1992年 | 6篇 |
1991年 | 11篇 |
1990年 | 6篇 |
1989年 | 17篇 |
1988年 | 27篇 |
1987年 | 21篇 |
1986年 | 23篇 |
1985年 | 13篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 14篇 |
1980年 | 6篇 |
1979年 | 5篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1976年 | 5篇 |
1975年 | 9篇 |
1974年 | 1篇 |
排序方式: 共有561条查询结果,搜索用时 15 毫秒
101.
102.
ES2 is a gene deleted in DiGeorge syndrome (DGS) and velocardiofacial
syndrome (VCFS) which has homologs in species as distant as Caenorhabditis
elegans and Drosophila . The function of ES2 is unknown, and the predicted
protein sequence does not contain motifs which suggest a particular role in
the developmental defects present in DGS and VCFS. Here we show that the
mouse homolog, Es2 , is transcribed in two forms resulting from the use of
alternative polyadenylation signals. Structural analysis programs predict
that the Es2 -encoded peptide has a coiled-coil domain, and transfection
experiments with an Es2 -green fluorescent protein (GFP) fusion construct
show that the peptide is recruited into the nucleus. Es2 is highly
expressed during mouse embryogenesis from E7 onwards. In situ hybridization
with an RNA probe revealed that the gene is widely expressed; however,
relatively higher expression was detected in the nervous system, with a
particularly high area of expression in a sub-region of the pons. The Es2
expression domain in the pons is shared with a Goosecoid-like gene ( Gscl)
which is located upstream of Es2 , and raises the possibility that the two
genes share regulatory elements and/or interact in this region of the
developing brain. This finding suggests that different genes in the deleted
region may be functionally related and might explain the occurrence of the
characteristic phenotype in patients with non-overlapping genetic lesions.
相似文献
103.
The H1-histaminergic agonists 2-pyridylethylamine (2-PEA) and 2-methylhistamine relaxed potassium-constricted, perfused, rabbit middle cerebral arteries at low concentrations (3 x 10(-11) to 3 x 10(-8) M) and constricted them at high concentrations (3 x 10(-7) to 3 x 10(-4) M). The relaxation and the contraction were not antagonized by propranolol (up to 3 x 10(-6) M) given 30 min before, suggesting that beta-adrenergic mechanisms were not involved. When 2-PEA was tested on arteries constricted with uridine triphosphate (UTP), similar results were obtained. In the UTP-constricted arteries, the 2-PEA-induced responses were competitively antagonized by 3 x 10(-9) M mepyramine. Together with previous work (Ea Kim et al., 1986), these results are compatible with the hypothesis that H1-receptors were responsible for both the relaxation and the contraction observed. When either indomethacin (10(-8), 3 x 10(-7), or 10(-5) M), dexamethasone (10(-5) M), or tranylcypromine (10(-5) or 10(-4) M) were tested on the response to 2-PEA or 2-methylhistamine, these inhibitors suppressed the relaxation or reversed it to a contraction. Furthermore, they potentiated the contraction induced by these agonists. These results favour the hypothesis that the H1-mediated relaxation in rabbit cerebral arteries may in part involve the release of prostaglandins, especially prostacyclin. The participation of such a prostanoid in histaminergic relaxation seems exclusively an H1-mediated mechanism, since the relaxation induced by the H2-agonist dimaprit (in the presence of mepyramine) was not antagonized by either indomethacin (3 x 10(-7) M) or tranylcypromine (10(-4) M). 相似文献
104.
In the period 1985-94, 237 out of 575 248 (0.41 per 1000) live born infants in Norway were reported to suffer culture-confirmed systemic group B streptococcal disease before their 90th day of life. The annual incidence increased from 0.20 per 1000 live births in 1985 to 0.64 in 1994, due solely to an increase in cases with an onset before the seventh day of life. Future studies should address the possible causes of this increase. 相似文献
105.
We measured umbilical cord aldosterone concentrations in 64 premature newborn infants. The median serum aldosterone level was 74.5 ngdl-1 (range 22-280 ng dl-1 ). Of the studied perinatal factors, only gestational age and birthweight presented a significant influence on the umbilical cord aldosterone levels. Newborn infants with a gestational age of over 34 weeks and a birthweight of over 2000 g had a significantly higher aldosterone cord level than those aged 34 weeks or younger and 2000 g or less in weight. 相似文献
106.
EA Mitchell BJ Taylor RP Ford AW Stewart DM Becroft JM Thompson R Scragg IB Hassall DM Barry EM Allen 《Archives of disease in childhood》1993,68(4):501-504
The association between dummy use and sudden infant death syndrome (SIDS) was investigated in 485 deaths due to SIDS in the postneonatal age group and compared with 1800 control infants. Parental interviews were completed in 87% of subjects. The prevalence of dummy use in New Zealand is low and varies within New Zealand. Dummy use in the two week period before death was less in cases of SIDS than in the last two weeks for controls (odds ratio (OR) 0.76, 95% confidence interval (CI) 0.57 to 1.02). Use of a dummy in the last sleep for cases of SIDS or in the nominated sleep for controls was significantly less in cases than controls (OR 0.44, 95% CI 0.26 to 0.73). The OR changed very little after controlling for a wide range of potential confounders. It is concluded that dummy use may protect against SIDS, but this observation needs to be repeated before dummies can be recommended for this purpose. If dummy sucking is protective then it is one of several factors that may explain the higher mortality from SIDS in New Zealand than in other countries, and may also explain in part the regional variation within New Zealand. 相似文献
107.
108.
109.
110.
Gender and the sudden infant death syndrome 总被引:1,自引:0,他引:1
Abstract A nationwide case-control study compared the prevalence and magnitude of risk factors for sudden infant death syndrome (SIDS) in male and female infants. The risk factors of SIDS and their magnitude for males and females are very similar. After adjustment for potential confounders male infants had a 1.42-fold (95% CI = 1.04, 1.94) increased risk of SIDS compared with females. Risk factors identified in most epidemiological studies are not the reason for the increased SIDS mortality seen in male infants. 相似文献