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实验通过酸碱中和沉淀法制备纳米羟基磷灰石粉体,考察了反应温度、陈化时间和反应溶剂体系等不同工艺条件对纳米羟基磷灰石粉体的粒度分布、反应收率等的影响。实验结果表明:球磨工序不影响粉体的粒度分布;分散剂可以有效改善粉体粒度的分布;综合考虑羟基磷灰石粉体的粒度、反应收率和反应效率,确定酸碱中和沉淀法制备纳米羟基磷灰石的反应时间为60 min、反应温度为60℃、陈化时间为1 h。 相似文献
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研究了一种作为药物载体的多孔球形羟基磷灰石生物材料的制备工艺。采用微乳液法先制得多孔球形碳酸钙,并以此为模板与磷酸氢二钠在一定条件下反应制备出直径约10μm的多孔球形羟基磷灰石。通过X射线衍射,扫描电子显微镜等手段对制备的羟基磷灰石的结构、组成和形貌进行表征,考察了不同反应温度、表面活性剂浓度、反应时间对多孔球形貌的影响,并对反应机理进行了初步探讨。结果表明,当制备多孔球形碳酸钙模板的温度为25℃、吐温-80浓度为3%且碳酸钙与磷酸氢二钠反应时间为30h时,得到的羟基磷灰石为5-10μm、分散性好的球形晶体。 相似文献
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沉淀法制备羟基磷灰石反应条件控制研究 总被引:1,自引:0,他引:1
为了方便快速地获得高纯度羟基磷灰石,以磷酸氢二铵和四水硝酸钙为原料,利用沉淀法制备纳米级羟基磷灰石粉末。描述了制备过程;对温度、pH、分散剂添加量、钙磷物质的量比、烧结温度等反应控制条件进行了研究;对钙磷物质的量比及烧结温度做了详细的讨论。制备羟基磷灰石的最佳工艺条件:pH为10.5,n(Ca) /n(P)=2.0,反应温度为40 ℃,剧烈搅拌2 h,陈化温度为50 ℃,分散剂添加量为3%(质量分数),以酒精洗涤,120 ℃干燥2 h,900 ℃烧结2 h。此法可得到分散性、均匀性好,纯度高、颗粒小、晶形完整的纳米级羟基磷灰石。 相似文献
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纳米羟基磷灰石是一种典型的生物活性材料,广泛应用于医学领域,近年来研究发现:纳米羟基磷灰石作为一种填料应用在牙膏中,对预防龋齿、牙周病具有重要作用.实验采用复分解沉淀法制备纳米羟基磷灰石粉体,用化学分析测定n(Ca)/n(P),采用激光粒度仪检测粒度分布,研究不同反应条件对粉体粒度的影响.研究结果表明:反应温度影响产物的结晶度,但对粒度分布影响不大;不同加料方式对粒度分布影响不大;快速搅拌有利于制备出粒度分布更好的粉体;缓慢的加料速度更有利于制备出粒度分布好的粉体;适度煅烧对晶相和结晶度有影响,但对粒度分布产生的影响不大. 相似文献
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采用正交设计方法,以羟基磷灰石作为载体,银离子和铈离子作为抗菌离子,采用离子交换方法制备羟基磷灰石抗菌剂,考察了硝酸银浓度、反应时间、反应温度和硝酸铈浓度等因素.运用X射线衍射谱研究了影响羟基磷灰石抗菌剂的微观结构;运用抑菌圈法表征所制备的抗菌剂的抗菌性能.研究表明:硝酸银浓度为0.2 mol/L、反应温度为30℃、反应时间为3 h和硝酸铈浓度为0.01 mol/L时对羟基磷灰石抗菌效果最好. 相似文献
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以氯化锌和氢氧化钠为原料,采用微波水热法制备了纳米氧化锌粉体,并采用X射线衍射(XRD)和透射电镜(TEM)对粉体的粒度、形貌、纯度进行了表征。通过单因素实验考察了反应温度、微波反应时间、微波功率、锌离子与氢氧根的浓度比等因素对氧化锌粉体的产率和粒径的影响,再通过正交试验得到最优制备条件。最佳制备工艺条件:锌离子与氢氧根的浓度比为1∶1.2、反应温度为 120 ℃、反应时间为 10 min、微波功率为500 W。在此条件下所得氧化锌粉体的晶型为六方晶相,产率达到93.5%,平均粒度约70 nm,粒径分布较窄,结晶完整。 相似文献
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M. S. J. Simmonds W. M. Blaney F. Delle Monache M. Marquina Mac-Quhae G. B. Marini Bettolo 《Journal of chemical ecology》1985,11(12):1593-1599
Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria. 相似文献
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It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples. 相似文献
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Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed. 相似文献
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中蓝晨光化工研究院有限公司《塑料工业》编辑部 《塑料工业》2009,37(3)
收集了2007年7月~2008年6月世界塑料工业的相关资料,介绍了2007~2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍. 相似文献
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中蓝晨光化工研究院《塑料工业》编辑部 《塑料工业》2007,35(3):1-25,67
收集了2005年7月~2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、通用热固性树脂(酚醛、聚氨酯、不饱和树脂、环氧树脂)、特种工程塑料(聚苯硫醚、液晶聚合物、聚醚醚酮)的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。 相似文献
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Inorganic/organic hybrid materials have considerable promise and are beginning to become a major area of research for many
coating usages, including abrasion and corrosion resistance. Our primary approach is to prepare the inorganic phase in situ
within the film formation process of the organic phase. The inorganic phase is introduced via sol-gel chemistry into a thermosetting
organic phase. By this method, the size, periodicity, spatial positioning, and density of the inorganic phase can be controlled.
An important aspect of the inorganic/organic hybrid materials is the coupling agent. The initial task of the coupling agent
is to provide uniform mixing of the oligomeric organic phase with the sol-gel precursors, which are otherwise immiscible.
UV-curable inorganic/organic hybrid systems have the advantages of a rapid cure and the ability to be used on heat sensitive
substrates such as molded plastics. Also, it is possible to have better control of the growth of the inorganic phase using
UV curing. It is our ultimate goal to completely separate the curing of inorganic and organic phases to gain complete control
over the morphology, and hence optimization of “all” the coating properties. Thus far, it has been found that concomitant
UV curing of the inorganic and organic phases using titanium sol-gel precursors afforded nanocomposite coatings which completely
block the substrate from UV light while maintaining a transparent to visible light. Also, it has been found that the morphology
of the inorganic phase is highly dependent on the concentration and reactivity of the coupling agent.
Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004, in Chicago,
IL. 相似文献