排序方式: 共有5条查询结果,搜索用时 15 毫秒
1
1.
研究超声波经过两个烧结样品的行为.两个烧结样品为有序的面心立方结构,它们的结构几乎相同.研究表明:在两个有序的准均匀的介质中分别有一个禁带区域.就禁带区域而言,在两个样品中产生禁带的区域非常接近.同时在禁带出现的区域群速度为负值.我们的结果表明群速度的负值的确存在于有序介质中的禁带区域内. 相似文献
2.
3.
Vitamin A and the regulation of fat reserves 总被引:7,自引:0,他引:7
4.
Yvonne G. J. van Helden Sandra G. Heil Frederik J. van Schooten Evelien Kramer Susanne Hessel Jaume Amengual Joan Ribot Katja Teerds Adrian Wyss Georg Lietz M. Luisa Bonet Johannes von Lintig Roger W. L. Godschalk Jaap Keijer 《Cellular and molecular life sciences : CMLS》2010,67(12):2039-2056
Beta-carotene 15,15′-monooxygenase 1 knockout (Bcmo1 ?/?) mice accumulate beta-carotene (BC) similarly to humans, whereas wild-type (Bcmo1 +/+) mice efficiently cleave BC. Bcmo1 ?/? mice are therefore suitable to investigate BC-induced alterations in gene expression in lung, assessed by microarray analysis. Bcmo1 ?/? mice receiving control diet had increased expression of inflammatory genes as compared to BC-supplemented Bcmo1 ?/? mice and Bcmo1 +/+ mice that received either control or BC-supplemented diets. Differential gene expression in Bcmo1 ?/? mice was confirmed by real-time quantitative PCR. Histochemical analysis indeed showed an increase in inflammatory cells in lungs of control Bcmo1 ?/? mice. Supported by metabolite and gene-expression data, we hypothesize that the increased inflammatory response is due to an altered BC metabolism, resulting in an increased vitamin A requirement in Bcmo1 ?/? mice. This suggests that effects of BC may depend on inter-individual variations in BC-metabolizing enzymes, such as the frequently occurring human polymorphisms in BCMO1. 相似文献
5.
世界的生物多样性很大程度上受到传统农业耕作方式的保护。这些生态上复杂的农业系统与作物遗传多样性中心相联系,有传统的栽培品种或“地方品种”,作为世界作物遗传资源的重要组成,还有野生的植物和动物种群,作为生物资源服务于人类。 相似文献
1