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采用超声波细胞破碎和索氏回流相结合的方法对马尾藻(Sargassum sp.)总脂质进行了提取,对提取过程中的超声波细胞破碎功率和时间、料液比、溶剂等关键因素进行了优化;对总脂质中的多不饱和脂肪酸进行了分离,并分析了马尾藻脂肪酸组成成分和含量。结果显示,总脂质的最佳提取条件为超声破碎功率80 W、破碎时间20 min、料液比(m/m)1:8、石油醚(60~90℃)为溶剂、85℃水浴回流8 h;总脂质最高提取率为1.77%,其中总脂肪酸平均含量为30.84%;总脂肪酸中共含有11种成分,多不饱和脂肪酸含量约占13.21%~14.60%;薄层色谱分离出2种多不饱和脂肪酸C18:2ω6和C20:4ω6。 相似文献
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利用超弹性SMA螺栓梁柱节点的耗能能力和自复位特性，将其引入到耗能跨而构建"自复位耗能跨"，基于既有的节点试验研究结果对结构体系的滞回性能进行了探讨。在此基础上，以具有旗形滞回特征的单自由度体系为工具，对配置自复位耗能跨低多层钢框架体系的能量系数进行推导。能量系数可以合理量化具有旗形滞回规则结构的峰值响应需求，能量系数越低，表明地震动下结构的峰值响应越低。为了阐明滞回参数对能量系数的影响，对具有不同滞回参数组合可代表低多层结构的等效SDOF体系进行了非线性动力分析，参数组合包括周期、屈服后刚度比、延性系数及能量比。同时对能量系数的离散性也进行了分析。结果表明:能量系数及能量系数的离散性受结构周期、屈服后刚度比及延性系数影响较大，受能量比的影响较小。 相似文献
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基于TM/ETM+数据,利用地表能量平衡原理,结合改进了温度算法和地表宽波反照率算法的SEBS模型,对巴丹吉林沙漠东南部苏木吉林南湖2000-2013年的湖面蒸发进行了反演.利用安装在湖面的E601型蒸发皿实测数据对反演结果进行验证,通过相关性分析发现,利用阿拉善右旗气象数据结合SEBS模型计算的湖面蒸发值与蒸发皿实测值相关性较好,R2>0.95,两者的均方根误差RMSE为0.313 mm,平均绝对百分比误差MAPE为8.17%.给出了折算方程,折算系数为0.621,并算得2000-2013年苏木吉林南湖湖面年平均蒸发量为1 287.544 mm.苏木吉林南湖湖面蒸发与气温相关性最好,日照时数次之,与风速的相关性最弱. 相似文献
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Using historical and 2010 field data, the distribution of nutrients in the northern Beibu Gulf of China is described. There was a decreasing trend in the concentration of nutrients from the north coast to offshore waters of the northern Beibu Gulf, reflecting the influence of inputs from land-based sources. High concentrations of dissolved inorganic nitrogen （DIN） and phosphate （PO4-P） occurred mainly at Fangchenggang Bay, Qinzhou Bay, and Lianzhou Bay. Four different methods were used to assess eutrophication. The trophic status of the Beibu Gulf was characterized using the single factor, Eutrophication index （El）, Trophic index （TRIX） and Assessment of Estuarine Trophic Status （ASSETS） methods. Based on nutrient concentrations, 73.9% of DIN and 26.7% of PO4-P samples exceeded the fourth grade Seawater Quality Standard of China. Eutrophication index values varied widely, but higher levels of eutrophication were generally found in bays and estuaries. TRIX values ranged from 2.61 to 7.27, with an average of 4.98, indicating a mesotrophic and moderately productive system. A positive correlation between TRIX and harmful algal species richness and abundance was observed. The ASSETS model evaluates eutrophication status based on a Pressure-State-Response approach, including three main indices： influencing factors, overall eutrophic condition, and future outlook. The Beibu Gulf was graded as moderate using ASSETS. The single factor and Chinese nutrient index methods were considered inadequate for the assessment of trophic status. TRIX can be used as an indicator of trophic state and ASSETS showed good potential to assess eutrophication. The results of TRIX and ASSETS depend on threshold values. To establish these values, further research is required within the northern Beibu Gulf. 相似文献
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