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971.
972.
973.
Fernando Díaz Alonso Enrique Gonzlez Ferrads Juan Francisco Snchez Prez Agustín Miana Aznar Jos Ruiz Gimeno Jesús Martínez Alonso 《Journal of Loss Prevention in the Process Industries》2006,19(6):724-728
A number of models have been proposed to calculate overpressure and impulse from accidental industrial explosions. When the blast is produced by explosives, pyrotechnics or unstable substances, the TNT equivalent model is widely used. From the curves given by this model, data are fitted to obtain equations showing the relationship between overpressure, impulse and distance. These equations, referred to here as characteristic curves, can be fitted by means of power equations, which depend on the TNT equivalent mass. Characteristic curves allow determination of overpressure and impulse at each distance. 相似文献
974.
湘江流域洪水灾害综合风险评价 总被引:26,自引:4,他引:26
依据灾害系统理论,在综合考虑致灾因子、孕灾环境和承灾体的基础上,从致灾因子、孕灾环境的自然属性和承灾体的社会属性两方面出发,以县级行政单元为基本评价单元,进行了湘江流域洪水灾害的综合风险评价。在综合考虑降雨量、地形以及历史上洪水灾害发生频次等自然因素的条件下,利用地图代数分析得到了湘江流域洪水灾害危险性评价图;在综合考虑人口密度、耕地面积百分比、人均GDP和单位面积水库和塘坝容量等社会经济指标的基础上,利用模糊综合评判法得到了湘江流域洪水灾害脆弱性评价图。在此基础上采取“乘”模型的计算公式,即风险=危险性×脆弱性,将湘江流域洪水灾害风险划分为高风险、较高风险、中等风险、较低风险和低风险5个等级,并借助地理信息系统软件编制了湘江流域洪水灾害综合风险等级评价图。 相似文献
975.
Riverbed sediments from an estuary historically affected by wastes discharged by several phosphate fertiliser plants and enriched in uranium-series radionuclides were operationally speciated using a Tessier-based method. In each selective fraction the (226)Ra content was determined by alpha-particle spectrometry after radiochemical isolation and electrodeposition onto stainless steel planchets. These studies were performed in (226)Ra-polluted estuarine sediments collected one year after anthropogenic discharges had ceased in order to obtain useful information about the operational forms in which this radionuclide remains associated with the sediments at this time. The results obtained revealed that one year after (226)Ra inputs had stopped, the radionuclide was associated mostly with the more refractory forms. Consequently, it is possible to foresee little potential remobilisation of (226)Ra contamination from sediments to the aqueous phase in the future under normal environmental conditions. 相似文献
976.
977.
978.
Many facets of coral research require coral colony surface area estimates. This study developed a relationship between the
two-dimensional (2D) projected area and the three-dimensional (3D) whole colony surface area for two commonly studied Indo-Pacific
coral species: Pocillopora damicornis and Stylophora pistillata. The surface index function was used to measure the growth of colonies in situ around Heron reef on the southern Great Barrier
Reef. The results show that while growth between the two species was not significantly different when measured in two dimensions,
the 3D area showed significantly different growth rates with S. pistillata growing at almost double the rate of P. damicornis. The study demonstrates that it is possible to make reliable estimates of the 3D surface area of entire colonies of these
complex branching coral species, using the plan view of the coral and a pre-determined surface index function. In addition,
this study shows that the 3D surface area provides a more useful measure of colony growth than the traditional methods of
either 2D area or longest dimension. 相似文献
979.
Bettina Mahler Viviana A. Confalonieri Irby J. Lovette Juan C. Reboreda 《Behavioral ecology and sociobiology》2008,62(7):1193-1199
For avian brood parasites in which individual females are host-specialists, the arms race between hosts and parasites has
favored egg color polymorphism in the parasite, with female lineages laying mimetic eggs that resemble those of the host species
they parasitize. Female sex-linked inheritance of egg color fosters evolutionary stability of egg polymorphism if female lineages
show both consistent eggshell color and host use. This co-evolutionary relationship is unlikely to occur if individual brood
parasites use different hosts or if egg color is not maternally inherited. The shiny cowbird (Molothrus bonariensis) is an extreme generalist brood parasite that shows a very high degree of egg polymorphism. We tested whether egg spotting
in this species has female sex-linked inheritance. If genetic factors controlling the expression of egg spotting were present
on the female-specific W chromosome, we expected co-segregation between spotting patterns and mtDNA haplotypes, as both W
and mtDNA are maternally inherited. In contrast to the known maternal inheritance of spotting patterns in great tits, we found
no associations between eggshell spotting and mtDNA haplotypes, which suggests that eggshell spotting is not maternally inherited
in this cowbird species. 相似文献
980.
通过半化学合成方法获得具有大肠杆菌密码子偏爱性的人α-防御素(Human α-defensin或human neutrophil peptide,HNP)HNP-2基因.将其克隆到pET-32a( )表达载体,构建了重组表达质粒pET-32a( )/HNP-2.分别转化大肠杆菌BL21(DE3),ER2566以及Origami B(DE3)宿主菌,经过表达条件的优化,结果在大肠杆菌Origami B(DE3)宿主菌中得到了HNP-2基因高效率可溶性的表达,融合蛋白表达量占细菌总蛋白的60%以上.为避免表达产物水解,得到更稳定的人α-防御素,尝试以环化形式和酰胺化形式表达人α-防御素.为得到环化形式的表达,采用intein作为工具,利用其可剪接extein的特点,将其N端区域和C端区域分别融合到HNP-2的C端和N端,其两端的intein片段可将其拼接成环肽.以此为基础构建了环化表达质粒,并对表达条件进行了探索.本文采用了一种新的酰胺化方法,即将intein与HNP-2融合表达,intein对目的短肽进行酰胺化修饰.图6表1参16 相似文献