共查询到20条相似文献，搜索用时 62 毫秒
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丁忱陈顺玉肖秀峰 《福建工程学院学报》2020,(1):12-17
采用氨解结合乳化及热致相分离的技术来制备改性聚乳酸微球,通过浸泡法让卵磷脂包裹在改性微球上,进一步提高改性微球的亲水性。探讨了卵磷脂溶液的浓度、浸泡时间对改性微球形貌和亲水性能的影响。实验结果表明,卵磷脂修饰改性微球的最佳制备工艺条件为:卵磷脂溶液的浓度为1%,浸泡时间为5h,在此条件下制备的微球卵磷脂包裹均匀且亲水性得到了改善。通过红外光谱,X射线光电子能谱表征微球,结果表明卵磷脂已经成功接枝到改性微球上,通过水接触角测试,卵磷脂修饰后的改性微球亲水性得到了进一步提高。 相似文献
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以壳聚糖为原料,通过乳化交联工艺制备壳聚糖微球,应用显微镜等考察其理化特性,利用统计学方法对微球粒径分布进行表征.结果表明:壳聚糖微球的理化特性受工艺条件如醋酸浓度、壳聚糖的脱乙酰度、壳聚糖醋酸溶液的浓度、交联剂的用量等因素的影响,还受到体系温度、搅拌速度和反应时间等条件的影响;通过乳化交联法可制备得到窄分布壳聚糖微球. 相似文献
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采用乳化-交联法研究了左氧氟沙星磁性明胶微球的制备及其缓释性能.选取左氧氟沙星与明胶的比例、水油比、明胶浓度、戊二醛用量四个因素进行正交实验,优化最佳合成工艺.采用动态透析法测定载药微球的体外释放特性,同时对载药微球的形态、粒径、磁性及包覆情况进行表征.结果表明,载药微球最佳制备工艺为:明胶浓度15%,左氧氟沙星明胶比1∶2,水油比1∶5,戊二醛用量3.6mL;包封率为8.89%,载药量为51.36%;微球5h体外累积释药百分率人工肠液中达到64%,人工胃液中达到72%,具有较好的缓释性能,体外释放符合一级动力学方程;磁性明胶微球成球性良好,分布均匀,Fe3O4及左氧氟沙星被明胶包覆. 相似文献
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本介绍了新型非金属材料Si3N4利用反应烧结方法（简称RBSN）的制取过程,并以MgO,Al2O3,Y2O3和ZrO2为助剂,探讨烧结助剂和成型工艺对制品性能的影响;温度和助剂对氮化率的影响;ZrO2含量、烧结时间和气氛对制品烧结性能的影响。为提高制品的致密度和机械强度等方面做了一定的工作。 相似文献
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吸收微波与红外能量的微陶瓷球 总被引：4，自引：0，他引：4
时杰 《中国科教创新导刊》2000,(2)
美国SDS（SpectralDynamicsSystems）公司生产的微陶瓷球粉末能吸收微波能量,把它添加在普通的漆中,再把漆喷涂在飞机和车辆上,就可减小它们的雷达与红外特征,即提高隐形能力,还可以涂覆在电子设备上来对付电磁干扰。SDS公司生产的微陶瓷球粉末名为Cenosphere,由覆有金属的微空心陶瓷球组成。这家公司生产的粉末不仅能吸收一些特定频率的电磁波,而且采用金属覆层可同时吸收雷达和红外能量。微陶瓷球粉末所吸收能量的频率由空心球的直径、用于涂覆球的金属及其厚度确定。Cenosphere球直径的范围为5－75微米,是以烧煤电厂的飞及… 相似文献
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孟玲 《连云港职业技术学院学报》2013,(4):19-23
对高岭土微球上原位晶化合成NaY沸石分子筛进行了探索研究,并取得了一定的结果：在选定的晶化液体系下优化和确定了高岭土微球最佳配方,液相中微球浓度的最佳值为0．50基准浓度。综合结晶度和硅铝比两产品指标,选定最佳SiO2／H2O为基准×1．1。原位晶化产物NaY分子筛结晶度达到40％,骨架SiO2／Al2O3为5．9,较宽的最佳微球组成合成出了高分子筛含量高硅铝比NaY／高岭土复合分子筛。 相似文献
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以ZnO、Al2O3粉体为原料,采用常压烧结方法制备高导电性Al:ZnO(AZO)陶瓷靶材,并系统研究了不同的成型压力、烧结工艺及其烧结温度对靶材电学特性和密度的影响。结果表明:成型压力的大小对于ZAO靶材本身的密度、成品率及最后烧结的性能都有很大的影响。成型压力为14Mpa时,靶材的电阻率最小,为0.35Ωcm。烧结温度的选择也是制备靶材的关键,为了避免靶材出现断层、上表面壳曲、微裂纹甚至开裂现象,要采用缓慢升温,长时间保温与缓慢降温的方法。实验表明,在1250℃时,AZO靶材表面平整致密,基本上达到了陶瓷靶材的烧结终点。 相似文献
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目的：制备BSA壳聚糖一海藻酸钠肠溶微囊并测试释放特性。方法：以微球的包封率为制备工艺优化指标,利用复凝聚法,通过正交实验筛选微球的最佳制备工艺奈件制备微球。结果：最优条件为牛血清白蛋白和海藻酸钠的比例为1：6,壳聚糖的浓度为0．1％（g／m1）,氯化钙的浓度为1％（g／m1）以及搅拌时间为1h。结论：BSA微囊在小肠中对蛋白有一定的缓释效果．交释效应不明显。 相似文献
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制备盐酸甲氧氯普胺海藻酸钙凝胶微球并考察不同因素影响下的释药性.采用滴制法制备盐酸甲氧氯普胺海藻酸钙凝胶微球,海藻酸浓度为2%,氯化钙浓度为1%,载药微球在酸性环境中具有良好的缓释效果,缓释时间能持续8h.盐酸甲氧氯普胺海藻酸钙缓释凝胶微球具有良好的应用前景. 相似文献
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本课题是研究高铝质多孔陶瓷的制备工艺 ,并在此基础上研制多孔衬底的制备工艺。一方面 ,以铝矾土为骨料 ,以粘土为结合剂 ,采用泥浆浇注法研制陶瓷管 ;另一方面 ,以α-Al2 O3粉料挤压成型研制出多孔陶瓷片。 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