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内科学是临床医学科学的核心学科,内科学的基本理论、基本知识和基本技能对临床各学科具有普遍的指导作用同时内科学也是临床学科的重要基础,提高课堂教学质量,既要求教师具备扎实的专业知识、渊博的学识,还要求教师注意授课的艺术。 相似文献
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采用燃烧合成法,制备Mg^2+掺杂的锂离子电池正极材料Li1.2Mn0.6Ni0.2O2。通过X射线衍射仪、拉曼光谱、扫描电子显微镜对所制备样品分别进行物相结构和形貌表征,并测试其电化学性能。结果表明:所制备样品具有良好的六方层状结构,粉体呈类球形形貌。通过Mg^2+掺杂,能够有效提高Li1.2Mn0.6Ni0.2O2材料的首次库仑效率、循环稳定性和高倍率容量。当Mg^2+掺杂量为0.02时,电池样品表现出良好的电化学性能。 相似文献
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以苦瓜为原料,用微波提取苦瓜中的苦瓜甙,考察了微波提取工艺中苦瓜投料物液比、微波输出功率、提取时间、溶剂用量等对苦瓜甙提取效果的影响,优选出微波提取的工艺方案.实验结果表明,最佳投料物液比1:3785,微波输出功率700 W,最佳提取时间为6 min,溶剂用量22 mL·g-1,浸润水用量6 mL·g-1.将微波技术运用在苦瓜甙的提取过程中,有效地强化了提取过程,缩短了提取时间,减少杂质. 相似文献
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Yttrium aluminum garnet structure phosphors Lu2CaMg2Si3O12:Mn2+ were synthesized by conventional high temperature solid-state reaction in reductive atmosphere. The structure and optical properties of samples were characterized by application of powder X-ray diffraction (XRD) and photoluminescence spectroscopy. Results of X-ray diffraction (XRD) analysis showed that the phosphors mainly presented garnet structure with a few weak peaks of impurity phases. Lu2-xCaMg2Si3O12:xMn2+ (x=0.01-0.8) phosphors showed a broad emission band peaking at around 590 nm under ultraviolet (UV) light of 408 nm when Mn2+ concentration was less than 0.08 mol. With an increase in the Mn2+ concentration (above 0.08), another broad emission band peaking at 720 nm besides 590 nm was observed, which may be due to manganese ion having different valence and occupying different host lattice. The critical quenching concentrations of manganese ion in the wavelength of 590 and 720 nm were about 0.06 and 0.2 mol, respectively. With 408 nm excitation wavelength, emission color of the samples had a red shift trend as the Mn2+ concentration increased. All the results indicated that the Lu2CaMg2Si3O12:Mn2+ phosphors could be applicable to n-UV based white LEDs. 相似文献
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