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椭圆弧加圆弧型封头最小有效厚度计算公式论证 被引量:4
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作者 李业勤 刘彬 张阳 《石油化工设备》 CAS 2021年第4期48-51,共4页
采用无力矩理论对椭圆弧加圆弧型封头、标准椭圆形封头及标准碟形封头内压稳定性进行分析比较,认为椭圆弧加圆弧型封头比标准椭圆形封头及标准碟形封头的力学性能优越,提高了弹塑性极限许可载荷及应力分析设计许可载荷。对3种封头进行... 采用无力矩理论对椭圆弧加圆弧型封头、标准椭圆形封头及标准碟形封头内压稳定性进行分析比较,认为椭圆弧加圆弧型封头比标准椭圆形封头及标准碟形封头的力学性能优越,提高了弹塑性极限许可载荷及应力分析设计许可载荷。对3种封头进行的线弹性和弹塑性有限元分析表明,椭圆弧加圆弧型封头可与筒体等厚度投料,或投料厚度比标准椭圆形封头小,节省材料且方便备料。椭圆弧加圆弧型封头弯角处的周向压应力比标准碟形封头的小,为防内压失稳,封头有效厚度应不小于封头内直径的0.15%。论证了椭圆弧加圆弧型封头最小有效厚度计算的依据。 展开更多
关键词 封头 椭圆弧加圆弧型 有效厚度 内压稳定性 计算公式 论证
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Determination of Internal Controls for Quantitative Gene Expression of Isochrysis zhangjiangensis at Nitrogen Stress Condition 被引量:1
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作者 WU Shuang ZHOU Jiannan +1 位作者 CAO Xupeng XUE Song 《Journal of Ocean University of China》 SCIE CAS 2016年第1期137-144,共8页
lsochrysis zhangfiangensis is a potential marine microalga for biodiesel production, which accumulates lipid under ni- trogen limitation conditions, but the mechanism on molecular level is veiled. Quantitative real-ti... lsochrysis zhangfiangensis is a potential marine microalga for biodiesel production, which accumulates lipid under ni- trogen limitation conditions, but the mechanism on molecular level is veiled. Quantitative real-time polymerase chain reaction (qPCR) provides the possibility to investigate the gene expression levels, and a valid reference for data normalization is an essential prerequisite for firing up the analysis. In this study, five housekeeping genes, actin (ACT), α-tubulin (TUA), β-tubulin (TUB), ubiquitin (UBI), 18S rRNA (18S) and one target gene, diacylglycerol acyltransferase (DGAT), were used for determining the reference. By analyzing the stabilities based on calculation of the stability index and on operating the two types of software, geNorm and bestkeeper, it showed that the reference genes widely used in higher plant and microalgae, such as UBI, TUA and 18S, were not the most stable ones in nitrogen-stressed 1. zhangjiangensis, and thus are not suitable for exploring the mRNA expression levels under these experi- mental conditions. Our results show that ACT together with TUB is the most feasible internal control for investigating gene expres- sion under nitrogen-stressed conditions. Our findings will contribute not only to future qPCR studies of/. zhangfiangensis, but also to verification of comparative transcriptomics studies of the microalgae under similar conditions. 展开更多
关键词 CHRYSOPHYTA Isochrysis zhang/iangensis nitrogen deficiency lipid accumulation reference gene selection
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