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51.
Summary The right wing bud of 4-day-old chick embryos is suggested as a cultivation site for embryonic epithelial membranes. 相似文献
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Nanostructured semiconductors have been researched intensively for energy conversion and storage applications in recent decades. Despite of tremendous find- ings and achievements, the performance of the devices resulted from the nanomaterials in terms of energy conversion efficiency and storage capacity needs further improvement to become economically viable for subsequent commercializa- tion. Hydrogenation is a simple, efficient, and cost-effective way for tailoring the electronic and morphological properties of the nanostructured materials. This work reviews a series of hydrogenated nanostructured materials was produced by the hydrogenation of a wide range of nanomaterials. These materials with improved inherent conductivity and changed characteristic lattice structure possess much enhanced per- formance for energy conversion application, e.g., photo- electrocatalytic production of hydrogen, and energy storage applications, e.g., lithium-ion batteries and supercapacitors. The hydrogenation mechanisms as well as resultant properties responsible for the efficiency improvement are explored in details. This work provides guidance for researchers to use the hydrogenation technology to design functional materials. 相似文献
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Mikkelsen TS Wakefield MJ Aken B Amemiya CT Chang JL Duke S Garber M Gentles AJ Goodstadt L Heger A Jurka J Kamal M Mauceli E Searle SM Sharpe T Baker ML Batzer MA Benos PV Belov K Clamp M Cook A Cuff J Das R Davidow L Deakin JE Fazzari MJ Glass JL Grabherr M Greally JM Gu W Hore TA Huttley GA Kleber M Jirtle RL Koina E Lee JT Mahony S Marra MA Miller RD Nicholls RD Oda M Papenfuss AT Parra ZE Pollock DD Ray DA Schein JE Speed TP Thompson K VandeBerg JL Wade CM Walker JA Waters PD Webber C 《Nature》2007,447(7141):167-177
We report a high-quality draft of the genome sequence of the grey, short-tailed opossum (Monodelphis domestica). As the first metatherian ('marsupial') species to be sequenced, the opossum provides a unique perspective on the organization and evolution of mammalian genomes. Distinctive features of the opossum chromosomes provide support for recent theories about genome evolution and function, including a strong influence of biased gene conversion on nucleotide sequence composition, and a relationship between chromosomal characteristics and X chromosome inactivation. Comparison of opossum and eutherian genomes also reveals a sharp difference in evolutionary innovation between protein-coding and non-coding functional elements. True innovation in protein-coding genes seems to be relatively rare, with lineage-specific differences being largely due to diversification and rapid turnover in gene families involved in environmental interactions. In contrast, about 20% of eutherian conserved non-coding elements (CNEs) are recent inventions that postdate the divergence of Eutheria and Metatheria. A substantial proportion of these eutherian-specific CNEs arose from sequence inserted by transposable elements, pointing to transposons as a major creative force in the evolution of mammalian gene regulation. 相似文献
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不同声学边界长空间内声场传播的相干模型 总被引:3,自引:0,他引:3
由于长空间的特殊空间尺寸,基于传统室内声学理论所假设的扩散声场分布规律和混响规律在长空间不完全适用.基于几何声学的虚源法可以对长空间的声场的传播进行研究.然而,虚源法建模忽略了长空间中声线在边界多次反射产生的干涉效应.在虚源法的基础上,通过对虚源之间的相干求和,考虑了多次反射形成的无限个虚源之间的干涉效应,并且将各不相同的边界阻抗率加入到模型中,实现了一种预测矩形长空间中声场的传播的复虚源模型.实验所用长空间的墙壁分别是密度板和吸声材料,以模拟不同的阻抗边界.实验采用衰减系数逾量描述数值模拟和实际测量的结果.实验证明了所提理论模型的有效性,所提理论模型的预测结果可以较好地模拟出不同边界长空间声场的衰减趋势,反映出不同频率的声波在长空间中的传播趋势,比基于声线法的软件ODEON的结果更接近实验结果. 相似文献
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Today’s and tomorrow’s imaging and circulating biomarkers for pulmonary arterial hypertension 总被引:1,自引:1,他引:0
Barrier M Meloche J Jacob MH Courboulin A Provencher S Bonnet S 《Cellular and molecular life sciences : CMLS》2012,69(17):2805-2831
The pathobiology of pulmonary arterial hypertension (PAH) involves a remodeling process in distal pulmonary arteries, as well as vasoconstriction and in situ thrombosis, leading to an increase in pulmonary vascular resistance, right heart failure and death. Its etiology may be idiopathic, but PAH is also frequently associated with underlying conditions such as connective tissue diseases. During the past decade, more than welcome novel therapies have been developed and are in development, including those increasingly targeting the remodeling process. These therapeutic options modestly increase the patients' long-term survival, now approaching 60% at 5 years. However, non-invasive tools for confirming PAH diagnosis, and assessing disease severity and response to therapy, are tragically lacking and would help to select the best treatment. After exclusion of other causes of pulmonary hypertension, a final diagnosis still relies on right heart catheterization, an invasive technique which cannot be repeated as often as an optimal follow-up might require. Similarly, other techniques and biomarkers used for assessing disease severity and response to treatment generally lack specificity and have significant limitations. In this review, imaging as well as current and future circulating biomarkers for diagnosis, prognosis, and follow-up are discussed. 相似文献
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