According to the characteristics of stone along the KKH-2 project in Pakistan, the applicability of gravel and machine-made sand for road engineering was studied. Through investigation, the types of stone along the pr...According to the characteristics of stone along the KKH-2 project in Pakistan, the applicability of gravel and machine-made sand for road engineering was studied. Through investigation, the types of stone along the project were relatively simple, and the stone materials used for road construction were mainly limestone, sandstone and pebbles, and the reserves?were?abundant. The experiment research and analyses comparisons of the parameters and road performance characteristics of natural gravel materials were carried out, and the design parameters and road performance indicators of natural grit in the current code were supplemented and adjusted to make it more suitable for Pakistan to use natural gravel materials for road construction. Thesis combines the project,?proposing that mechanism sand and natural sand mixed concrete?is?not inferior?tonatural sand mixed concrete in terms of technical performance, and the overall cost is lower than that of natural sand mixed concrete. The research results are of great significance for saving engineering construction costs, ensuring road performance and prolonging service life.展开更多
文摘According to the characteristics of stone along the KKH-2 project in Pakistan, the applicability of gravel and machine-made sand for road engineering was studied. Through investigation, the types of stone along the project were relatively simple, and the stone materials used for road construction were mainly limestone, sandstone and pebbles, and the reserves?were?abundant. The experiment research and analyses comparisons of the parameters and road performance characteristics of natural gravel materials were carried out, and the design parameters and road performance indicators of natural grit in the current code were supplemented and adjusted to make it more suitable for Pakistan to use natural gravel materials for road construction. Thesis combines the project,?proposing that mechanism sand and natural sand mixed concrete?is?not inferior?tonatural sand mixed concrete in terms of technical performance, and the overall cost is lower than that of natural sand mixed concrete. The research results are of great significance for saving engineering construction costs, ensuring road performance and prolonging service life.
文摘为探讨锦鲤的抗逆机理,在实验室条件下研究了持续热应激对大正三色锦鲤非特异性免疫指标及HSP70基因相对表达量的影响。分别于应激前、应激后2、6、10、14、18、22、26 h进行取样测定呼吸爆发、补体蛋白3(C3)、超氧化物歧化酶(SOD)、丙二醛(MDA)以及热休克蛋白70(HSP70)基因的相对表达量。结果发现,热应激后呼吸爆发降低,在应激后2、10、18~26h降低显著(P<0.05);热应激2 h后血清中C3含量略有上升,应激6~26 h过程中与应激前相比均下降,应激14~22 h显著地下降(P<0.05);热应激下血清中SOD有上升的趋势,但差异不显著(P>0.05);热应激下,血清中MDA浓度升高,应激10~18 h上升显著(P<0.05);应激后2、26 h HSP70基因的相对表达量与应激前相比显著性地上升了5.93倍、2倍(P<0.05),应激后6~22 h HSP70基因的相对表达量与应激前水平无显著性差异(P>0.05)。结果表明,热应激影响锦鲤非特性免疫指标,降低锦鲤非特异性免疫力;HSP70的表达受热应激调节,热应激下诱导合成的HSP70对锦鲤起到一定的应激保护作用。