共查询到20条相似文献，搜索用时 78 毫秒
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通过溶胶-凝胶法合成了纳米ZnO粉体,并对所制得ZnO粉体在不同温度下进行了热处理,应用X射线衍射(XRD)对热处理后的样品进行了相表征,用红外吸收光谱(FT-IR)对不同热处理温度下的样品进行了结构分析,用透射电子显微镜(TEM)对热处理后的样品进行了形貌表征,XRD谱表明,在300℃热处理下的ZnO粉体已经成相并具有良好的结晶状态,根据Scherrer公式计算的ZnO晶粒尺寸与由TEM估算ZnO颗粒的晶粒尺寸基本保持一致,ZnO颗粒的晶粒尺寸随着热处理温度的提高而增大。 相似文献
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SiO_2-WO_3纳米材料的固相合成研究 总被引：3，自引：0，他引：3
魏少红 《新乡师范高等专科学校学报》2002,16(4):23-24
用固相法制得了纳米级xwt%SiO2 +WO3(x =0 ,3,10 ,15 ,2 0 )的粉体材料 ,进行了XRD物相分析 ,以TEM观察其形貌并测得平均粒径。结果表明 :该方法可获得单斜晶系的WO3纳米粉体 ,晶粒尺寸随SiO2 掺杂量增加而减小 ,粉体粒径范围为 5 0nm～ 6 0nm。 相似文献
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溶胶-凝胶法合成纳米γ-Al2O3工艺研究 总被引：2，自引：0，他引：2
利用溶胶-凝胶法制备了纳米γ-Al2O3粉体,以透射电镜(TEM)、X射线衍射(XRD)等手段对所得的纳米γ-Al2O3进行了表征,对其制备过程中的诸多影响因素作了比较详细的分析。结果表明,选择适当的制备方法、煅烧温度以及分散剂的种类,能有效地阻止产物团聚,控制纳米粒子的形状和尺寸。 相似文献
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韩哲 《唐山师范学院学报》2005,27(5):14-16
研究了纳米氧化物掺杂对Ag/SnO2触头材料物理性能的影响.采用溶胶-凝胶法制备SnO2与各种掺杂氧化物(包括TiO2、ZnO、Sb2O3、CuO)的混合粉末.粉末的XRD、TEM表明,所得粉末为纳米级,且掺杂物离子能很好地进入到SnO2的晶格中;粉末的密度,电导率等测试表明SnO2的物理性能有了明显改善. 相似文献
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韩哲 《唐山师范学院学报》2005,27(5):14-16,30
研究了纳米氧化物掺杂对Ag／SnO2触头材料物理性能的影响。采用溶胶-凝胶法制备SnO2与各种掺杂氧化物（包括TiO2、ZnO、Sb2O3、CuO）的混合粉末。粉末的XRD、TEM表明，所得粉末为纳米级，且掺杂物离子能很好地进入到SnO2的品格中；粉末的密度，电导率等测试表明SnO2的物理性能有了明显改善。 相似文献
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采用溶胶-凝胶法,以硝酸铜、二氯化锡和钛酸四丁酯为原料,加入十六烷基三甲基溴化铵(CTAB)作软模板,制备CuO/SnO2/TiO2纳米复合物。分别用SEM、XRD、IR、UV-vis等对产物进行表征分析,CuO/SnO2/TiO2晶粒由锐钛矿相的TiO2、金红石相的SnO2和单斜晶系的CuO组成。以甲基橙为模拟污染物,研究其催化活性,结果表明CuO/SnO2/TiO2纳米复合物具有较好的光催化活性。 相似文献
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采用溶胶-凝胶法,以硝酸铜、二氯化锡和钛酸四丁酯为原料,加入十六烷基三甲基溴化铵(CTAB)作软模板,制备CuO/SnO2/TiO2纳米复合物。分别用SEM、XRD、IR、UV-vis等对产物进行表征分析,CuO/SnO2/TiO2晶粒由锐钛矿相的TiO2、金红石相的SnO2和单斜晶系的CuO组成。以甲基橙为模拟污染物,研究其催化活性,结果表明CuO/SnO2/TiO2纳米复合物具有较好的光催化活性。 相似文献
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以氯氧化锆、硝酸铈、硝酸铝为原料,采用化学沉淀法在经过扩孔处理的γ-Al2O3基载体上制备出Ce0.6Zr0.4O2/γ-Al2O3复合粉体。为有效去除水分,减少粉体团聚,采用正丁醇与粉体共沸蒸馏。采用XRD技术对所得粉体的晶型及相结构进行了表征。结果表明:Ce0.6Zr0.4O2/γ-Al2O3复合粉体中CeO2为立方晶型,随着焙烧温度的升高,样品的衍射峰依次变强,半高宽变窄,说明晶粒变大,晶体的完整性变好。 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献
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Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject. 相似文献
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Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities. 相似文献
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RUZBEHANI Mohsen 《重庆大学学报(英文版)》2004,3(1):20-25
1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec… 相似文献
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唐芳 《读与写:教育教学刊》2008,5(6)
During interview with English majors, it was found that a majority of students expressed disappointment with their experience of English literature classes. Students' dislike of learning English literature appears to be the major problem of teaching English literature in China. Reader response approach is a good way to solve this problem. In this paper, I explain the rationale behind the reader response approach, such as its origin, definition, features, assumptions, and strategies. Then I illustrate how reader response approach works as a teaching strategy by presenting several teaching models. At last I evaluate its usefuiness for teachers and present the advantages of reader response approach in Chinese context. 相似文献