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91.
固体生物质快速热解动力学参数计算 总被引:5,自引:0,他引:5
本文在介绍一个实验装置及其实验结果的基础上,运用化学动力学及热分析的基本原理对实验结果进行数学处理,得出木材快速热分解时气体生成的动力学表达式及其相应的动力学参数,并对实验结果进行讨论,说明应用该式计算木材热解时挥发份逸出的可靠性。 相似文献
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沙漠前沿不同植被恢复模式对风的影响 总被引:1,自引:0,他引:1
利用2006-2009年新疆奇台县沙漠前沿人工植被恢复区和天然植被恢复区监测到的风的相关数据,研究了不同时间尺度上天然和人工植被恢复模式对风的影响差异.结果表明:在年度尺度上,人工植被恢复区的无风天比天然植被恢复区多58.8 d/a,年均降低风速0.88m/s,多消抵65.2%的风动能,人工植被恢复对北向和西北向风的消... 相似文献
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Previously-frozen stores of organic carbon (C) are now subject to decomposition due to a warming Arctic climate and associated permafrost thaw; however, estimates of the amount of greenhouse gases (GHG) that may be released are not well constrained. Knowing more about the functions of the extant permafrost microbial community will inform this knowledge gap. The exploration of microbial functional traits may be useful to elucidate the relationship between microbial diversity and ecosystem function. We characterized the community traits and functional diversity of the bacterial and Archaeal component of the microbial community from three depths of permafrost, as well as the organic and mineral horizons of the seasonally-thawed active layer, by assessing ‘substrate-use richness,’ ‘substrate preference,’ ‘growth rate,’ ‘and substrate specific growth rate.’ We measured the microbial community response to 31 substrates with an EcoPlate (Biolog, Inc.) assay at three incubation temperatures (1, 10, and 20 °C) using a kinetic approach, and modeled the microbial response to each substrate with a modified logistic growth function. We hypothesized that the permafrost communities would be selected for high functional potential and activity at cold temperatures. Rather, we found that the permafrost community did not have a higher functional diversity or activity at 1 °C than the organic active layer soils. In addition, permafrost communities increased their growth rates with increasing temperature, indicating that the highest incubation temperature (20 °C) was below their temperature optimum for growth. As predicted, the permafrost communities did exhibit temperature dependent substrate preferences. Thus, permafrost microbial communities did not appear to be selected for higher metabolism and the ability to use a broad suite of substrates at low temperatures, which suggests that they may have limited function immediately following thaw when temperatures are near 0 °C. However, changes in community composition or additional permafrost warming will increase the functional capabilities of permafrost microbes to decompose the C stored in those soils. 相似文献
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氢醌对淹水土壤脲酶动力学特征的影响 总被引:2,自引:0,他引:2
通过模拟试验研究了正常水分和淹水条件下氢醌影响的土壤脲酶动力学特征。结果显示,培养时间、土壤类型、土壤水分及其相互作用显著影响土壤脲酶动力学参数的变化。与对照相比,HQ使土壤脲酶Km增加和Vmax降低,表明HQ属于典型的混合型抑制剂。随着培养时间延长,在正常水分和淹水条件下,HQ处理土壤脲酶Km降低,而Vmax和Vmax/Km升高。褐土脲酶Km的增加幅度及Vmax和Vmax/Km的降低幅度远远大于其它3种供试土壤。与正常水分相比,淹水对土壤脲酶动力学参数无显著性影响。相关分析表明,土壤脲酶动力学参数Km、Vmax和Vmax/Km与土壤理化性质存在显著的相关关系。 相似文献
98.
应用同步热分析仪,以不同升温速率对鸡粪进行热解,研究其热解特性和动力学。结果表明,鸡粪热解可以分为5个阶段,随着升温速率增加,反应的特征温度和最大失重速率变化较明显。根据Malek法确定热解机理为随机成核和随后成长,把试验数据代入热解鸡粪热解反应式拟合计算得到的活化能和频率因子,与Ozawa法计算的结果相同,确定活化能E为180.83 kJ/mol,频率因子lgA为14.27 s-1,反应级数n为1/3。通过常规热解试验,分析样品在一定温度的固体产率,得到的结果与热重试验的数据接近,验证了热重分析结果的可靠性。 相似文献
99.
Commercial baker's yeast consists of Saccharomyces cerevisae, however the strain can vary in each baker's yeast, which might influence the dough fermentation time. The scope of this research was to investigate the dough expansion of wheat doughs fermented by seven commercial baker's yeasts at different yeast concentrations (2.88·1011, 5.76·1011 and 8.64·1011 colony forming units/kg flour) and fermentation temperatures (5 °C, 15 °C, 25 °C and 35 °C). Dough expansion was investigated by monitoring the dough height and it was found to be described well by a first order kinetic model. Doughs fermented with four of the seven yeasts generally had higher kinetic rate constants and hence shorter fermentation times compared to fermentation with the other three yeasts. The shortest fermentation times were found for doughs fermented at 25 °C and the highest yeast concentration, a trend found for all the yeasts tested. The differences in the kinetic rate constants indicate a differentiation in yeast strain among the commercial baker's yeasts emphasising the great importance of the choice of baker's yeast for the dough fermentation time. 相似文献
100.
丝素蛋白膜作为葡萄糖氧化酶载体的研究 总被引:6,自引:0,他引:6
采用戊二醛共价交联法将葡萄糖氧化酶(GOD)固定在丝素膜上,探讨了酶的固定化方法,研究了固定化酶膜的动力学性质,并与包埋法制备的酶膜进行了比较。共价法可获得高活力的酶膜(534u/cm2),固定化过程中使用甲醇或戊二醛处理对酶活力有轻微影响。固定化GOD最适pH值向中性偏移(pH7.0),最适温度为50℃,热稳定性提高,表观米氏常数比溶液酶降低,酶膜的贮存稳定性良好。 相似文献