排序方式: 共有41条查询结果,搜索用时 375 毫秒
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采用柠檬酸-硝酸盐法合成了碱土金属双掺杂的Pr0.6CaxSr0.4-xFeO3-δ(X=0.0-0.4)系列复合氧化物粉体,用TG-DTA,XRD,FT-IR,SEM等手段对产物中钙钛矿物相的形成及微结构进行了表征,结果表明,样品在800℃焙烧2h后显现钙钛矿结构的主要衍射峰;随热处理温度的升高,XRD谱峰强度逐渐增大,1000℃煅烧2h即得到正交钙钛矿结构的单相固溶体;系列样品结晶化程度和晶粒尺寸随样品中Ca含量的增大而减小;电导率测试结果表明,Ca^2+、Sr^2+双掺杂样品的电导率随Sr^2+含量的增大而增大,低温段(T≤650℃)烧结陶瓷体的导电行为遵循小极化子导电机制。 相似文献
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Vicia faba L.seedlings were hydroponically cultivated in 0-12 mg/L of extraneous lanthanum(La) for 15 d to investigate ecotoxicological effects and risk assessment of rare earth elements(REEs).The results showed that reactive oxygen species(ROS) production suchas superoxide radical(O2.-) and hydrogen peroxide(H2O2) were overproduced at higher concentrations of La,resulting in oxidatively modified proteins and shoot growth retardation.While,superoxide dismutase(SOD),catalase(CAT),ascorbate peroxidase(APX) and guaiacolperoxidase(GPX) isoenzymes were elevated to some extent to eliminate excess of ROS.HSP70 production and endopeptidase isoenzymeswere also enhanced,which were involved in repairing or degradation of the oxidatively modified proteins due to La.Thus,the antioxidantisoenzymes,endoprotease isoenzymes and HSP70 worked cooperatively to alleviate the La-induced oxidative damage.The significant enhancement of CAT and APX isoenzymes and HSP70 could also be used as early bioindicators of La-polluted solution.The threshold doserange was firstly delimited as 1-2 mg/L of extraneous La,corresponding to 7.34-9.37 μg/g dry weight in the leaves.These results would behelpful to further understand the toxicological effects and possible mechanisms of REE(s) on crop seedlings. 相似文献
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基于3,5-Cl2-DMPAP在乙醇等溶剂中主要呈黄色或橙黄色,而在甲醇介质中呈紫红色,最大吸收峰红移100 nm左右,试剂对甲醇有独特的识别作用,建立了用二个波长测定吸光度计算甲醇汽油中甲醇含量的新体系,研究了测定条件的影响。方法简单、快速、选择性好,结果令人满意。 相似文献
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纳米Li4Ti5O12前驱体的电合成及其溶胶-凝胶过程 总被引:5,自引:0,他引:5
采用“牺牲”金属阳极溶解法在乙醇和乙酰丙酮混合溶液中,先加入0.12g锂片,在所得溶液中恒流为0.2A电解钛片6h,制得复合氧化物纳米粉体Li4Ti5O12的前驱体Li4Ti5(OEt)(24-n(acae)n[aeae为乙酰丙酮基]。产物通过红外光谱(FT IR)、X射线衍射(XRD)、电子透射显微镜(TEM)进行表征。实验表明,电解温度控制在35~40℃、导电盐Bu4NBr浓度为0.040-0.045mol/L之间电流效率达到90%左右;在温度为40℃、浓度为0.2mol/L、pH=8.5时进行水解,产率为89%,水解后的干凝胶粒径10~15nm。 相似文献
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锂、铝醇盐的电合成及其凝胶工艺 总被引:3,自引:0,他引:3
向0.035mol/L Bu4NBr的乙醇溶液中加入0.18g锂片,然后采用金属阳极溶解法控制电流为0.2A电解铝片6h,同时间断滴入1mL乙酰丙酮,制得纳米粉体LiAlO2的前驱体LiAl(OEt)(4-n)(acac)n(acac为乙酰丙酮基)。产物通过傅里叶变换红外光谱(FT-IR)、X射线衍射(XRD)、电子透射显微镜(TEM)进行表征。结果表明,电解温度为50℃、导电盐BU4NBr浓度为0.035mol/L时,电流效率达到90%以上;在温度为40℃,产物浓度为0.30mol/L,pH9.0时进行水解,产率可达94.8%;干凝胶粒径在Ф20~30nm之间。 相似文献
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废聚苯乙烯泡沫塑料制备防火涂料的研究 总被引:2,自引:0,他引:2
以改性的废聚苯乙烯泡沫塑料为成膜物,通过优选复合防火添加剂制备防火涂料。讨论了溶剂、防火体系等对涂层性能和防火效果的影响。 相似文献