全文获取类型
收费全文 | 272篇 |
免费 | 25篇 |
专业分类
297篇 |
出版年
2021年 | 5篇 |
2020年 | 3篇 |
2018年 | 5篇 |
2017年 | 4篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 11篇 |
2013年 | 7篇 |
2012年 | 8篇 |
2011年 | 6篇 |
2010年 | 11篇 |
2009年 | 5篇 |
2008年 | 10篇 |
2007年 | 5篇 |
2006年 | 10篇 |
2005年 | 10篇 |
2004年 | 3篇 |
2003年 | 7篇 |
2002年 | 6篇 |
2001年 | 7篇 |
2000年 | 6篇 |
1999年 | 7篇 |
1998年 | 3篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 7篇 |
1993年 | 3篇 |
1992年 | 8篇 |
1990年 | 4篇 |
1989年 | 7篇 |
1988年 | 3篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 7篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1967年 | 4篇 |
1962年 | 3篇 |
1961年 | 4篇 |
1959年 | 2篇 |
1958年 | 6篇 |
1955年 | 2篇 |
1952年 | 3篇 |
1879年 | 2篇 |
排序方式: 共有297条查询结果,搜索用时 15 毫秒
21.
Martin J McKeown Rafeef Abugharbieh Samantha Palmer Mechelle Lewis Xuemei Huang 《BMC neurology》2008,8(1):8
Background
Recent pathological studies have suggested that thalamic degeneration may represent a site of non-dopaminergic degeneration in Parkinson's Disease (PD). Our objective was to determine if changes in the thalami could be non-invasively detected in structural MRI images obtained from subjects with Parkinson disease (PD), compared to age-matched controls. 相似文献22.
The effect of neurotensin on submaximally-stimulated hepatobiliary and pancreatic secretion was studied in 6 healthy subjects. An intravenous infusion of neurotensin 1.4 ± 0.3 pmol/kg/min, designed to reproduce plasma neurotensin immunoreactivity levels within the physiological range, produced a significant increase in pancreatic bicarbonate output. Plasma concentrations of pancreatic polypeptide rose by 83 ± 16 pmol/l and were associated with a small reduction in trypsin, but no significant change in bilirubin outputs. 相似文献
23.
24.
25.
DFak56 is a novel Drosophila melanogaster focal adhesion kinase 总被引:2,自引:0,他引:2
Palmer RH Fessler LI Edeen PT Madigan SJ McKeown M Hunter T 《The Journal of biological chemistry》1999,274(50):35621-35629
The mammalian focal adhesion kinase (FAK) family of nonreceptor protein-tyrosine kinases have been implicated in controlling a multitude of cellular responses to the engagement of cell surface integrins and G protein-coupled receptors. We describe here a Drosophila melanogaster FAK homologue, DFak56, which maps to band 56D on the right arm of the second chromosome. Full-length DFak56 cDNA encodes a phosphoprotein of 140 kDa, which shares strong sequence similarity not only with mammalian p125(FAK) but also with the more recently described mammalian Pyk2 (also known as CAKbeta, RAFTK, FAK2, and CADTK) FAK family member. DFak56 has intrinsic tyrosine kinase activity and is phosphorylated on tyrosine in vivo. As is the case for FAK, tyrosine phosphorylation of DFak56 is increased upon plating Drosophila embryo cells on extracellular matrix proteins. In situ hybridization and immunofluorescence staining analysis showed that DFak56 is ubiquitously expressed with particularly high levels within the developing central nervous system. We utilized the UAS-GAL4 expression system to express DFak56 and analyze its function in vivo. Overexpression of DFak56 in the wing imaginal disc results in wing blistering in adults, a phenotype also observed with both position-specific integrin loss of function and position-specific integrin overexpression. Our results imply a role for DFak56 in adhesion-dependent signaling pathways in vivo during D. melanogaster development. 相似文献
26.
PURPOSE OF REVIEW: Despite improvements in the early management of acute coronary syndromes, the risk of major cardiovascular complications remains high. Lipid-modifying treatment with statins has the potential to further improve outcomes through improved endothelial function, antithrombotic and antiinflammatory actions. Statins are of proven benefit in patients with stable coronary heart disease. There has been speculation on potential mechanisms of benefit but, until recently, little data on the efficacy and safety of statins in the acute setting. Recent observational studies and randomized trials have addressed some of the questions regarding early initiation of statins in acute coronary syndromes. RECENT FINDINGS: Recent observational and randomized trials have shown that early commencement of statins in acute coronary syndromes is safe as early as 6 hours after the event and is likely to improve longer-term compliance. The current data are not sufficient to draw conclusions about the efficacy of statins early in the course of acute coronary syndromes. SUMMARY: Current management for acute coronary syndromes should include the commencement of statin therapy during initial hospital admission. This recommendation is based on safety and compliance data. More randomized trial evidence is required to determine whether early initiation will produce better outcomes than later initiation after an acute coronary event. 相似文献
27.
C. Timothy McKeown 《American anthropologist》2003,105(3):640-641
The Future of the Past: Archeologists, Native Americans, and Repatriation. Tamara L. Bray. New York: Garland Publishing. 2001. 252 pp. 相似文献
28.
Amy J. E. Healey Matthew W. Farthing Francis K. E. Nunoo Warren M. Potts Warwick H. H. Sauer Ilze Skujina Nathan King Sophie de Becquevort Paul W. Shaw Niall J. McKeown 《Journal of fish biology》2020,96(3):795-805
Two sister species of horse mackerel (Trachurus trachurus and T. capensis) are described that are intensively harvested in East Atlantic waters. To address long-standing uncertainties as to their respective geographical ranges, overlap and intraspecific population structure this study combined genetic (mitochondrial DNA and microsatellite) analysis and targeted sampling of the hitherto understudied West African coast. mtDNA revealed two reciprocally monophyletic clades corresponding to each species with interspecies nuclear differentiation supported by FST values. The T. trachurus clade was found across the north-east Atlantic down to Ghana but was absent from Angolan and South African samples. The T. capensis clade was found only in South Africa, Angola and a single Ghanaian individual. This pattern suggests that both species may overlap in the waters around Ghana. The potential for cryptic hybridization and/or indiscriminate harvesting of both species in the region is discussed. For T. capensis mtDNA supports high gene flow across the Benguela upwelling system, which fits with the species' ecology. The data add to evidence of a lack of significant genetic structure throughout the range of T. trachurus though the assumption of demographic panmixia is cautioned against. For both species, resolution of stock recruitment heterogeneity relevant to fishery management, as well as potential hybridization, will require more powerful genomic analyses. 相似文献
29.
30.