排序方式: 共有42条查询结果,搜索用时 15 毫秒
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以五水硝酸铋和五氧化二钒为原料,通过微波合成法制备了纳米BiVO4,采用X-射线衍射(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)表征了样品的形貌、结构和特性。XRD表明所制备的样品是纯的单斜晶型BiVO4;SEM显示样品的形貌呈层状结构;TEM进一步指出这些片层结构是由小粒子聚集而成的多孔结构。以催化降解甲基橙来考察其光催化性能。在100mL的10mg/L甲基橙溶液中加入0.12g经673K恒温热处理2h后的BiVO4及0.2mL H2O2,调节pH值为3.0,在可见光下照射90min后,降解率达到94.70%,催化性能良好。 相似文献
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以麻城福白菊为原材料,采用单因素及响应面优化超声辅助提取黄酮工艺条件,并评价最优条件下黄酮提取物的抗氧化活性。结果表明,超声波功率为440 W,超声温度为60 ℃,超声时间为50 min。在此条件下福白菊总黄酮的得率为7.15%。当福白菊黄酮浓度为0.05 g/L时,总还原能力最强,此时测得吸光度值为0.341;当福白菊黄酮浓度为0.50 g/L时,福白菊黄酮对2,2-联苯基-1-苦基肼基(DPPH)自由基清除率达81.25%,其对DPPH自由基的IC50值为0.191 g/L,表明其具有较好的抗氧化活性。 相似文献
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以茯苓菌种为研究对象,采用响应面法对其产茯苓粗多糖的发酵培养基组分进行优化。 在单因素优化的基础上,利用Plackett- Burman(PB)试验设计筛选出影响茯苓粗多糖产量的3个显著性因素:葡萄糖、酵母粉、硫酸镁。 利用响应面分析法(RSM)优化,得到 最佳培养基组分为:葡萄糖47.1 g/L、酵母粉20.5 g/L、硫酸镁1.8 g/L、蛋白胨30 g/L、硝酸钠5 g/L、磷酸二氢钾1.0 g/L、VB1 1 g/L、无水氯 化钙0.1 g/L。 在此优化条件下,茯苓粗多糖产量为138 mg/100 mL,是优化前的1.3倍。 相似文献
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以九资河茯苓为原料,采用超声波法提取茯苓多糖。以茯苓多糖得率为响应值,采用单因素试验及响应面试验对超声波提取茯苓多糖的工艺条件进行优化,并对其抗氧化活性进行研究。结果表明,超声波提取茯苓多糖的最佳工艺条件为超声波功率200 W,料液比1∶34(g∶mL),超声时间11 min。在此最优提取条件下,茯苓多糖得率为2.08%,较优化前(1.68%)提高16.85%。当茯苓多糖质量浓度为3.0 mg/mL时,总抗氧化能力最高,为0.22;当茯苓多糖质量浓度为2.5 mg/mL时,茯苓多糖对1,1-二苯基-2-苦肼基(DPPH)自由基的清除率最大,为13%,但均低于阳性对照维生素C。 相似文献
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采用超临界CO2流体萃取技术提取黑胡椒挥发油(black pepper oil,BPO),应用气相色谱-质谱联用技术对BPO进行分析,采用1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基清除法和还原能力法对BPO进行了体外抗氧化活性检验,并且采用酿酒酵母对BPO进行体内抗氧化活性检验。结果表明BPO主要成分为胡椒碱(40.2%),BPO对DPPH自由基的清除能力和还原能力略低于二丁基羟基甲苯和抗坏血酸。而且BPO不同程度地提高了CCl4、H2O2和CdSO4氧化应激胁迫下酵母细胞的存活率;较明显地降低了氧化应激胁迫下酵母细胞内氧化和膜脂质过氧化水平。实验结果还表明BPO抵抗脂质过氧化的机制很有可能与基因ctt1编码的过氧化氢酶有关。 相似文献
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Recent advances of flowering locus T gene in higher plants 总被引:1,自引:0,他引:1
Flowering Locus T (FT) can promote flowering in the plant photoperiod pathway and also facilitates vernalization flowering pathways and other ways to promote flowering. The expression of products of the FT gene is recognized as important parts of the flowering hormone and can induce flowering by long-distance transportation. In the present study, many FT-like genes were isolated, and the transgenic results show that FT gene can promote flowering in plants. This paper reviews the progress of the FT gene and its expression products to provide meaningful information for further studies of the functions of FT genes. 相似文献
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《NDT International》1989,22(5):304
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Grafting of methyl methacrylate (MMA) and styrene (St) onto polychloroprene latex (CRL) was carried out successfully using emulsion polymerization. The chemical structure of the grafted copolymer was characterized using Fourier transform infrared spectroscopy. The compatibilizing effects of the grafted polymer CRL-g-(MMA-co-St) on the CRL/styrene-acrylate emulsion (SAE) blend were investigated using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and mechanical testing. The results showed that the mechanical properties of the contained CRL-g-(MMA-co-St) blend improved significantly in comparison to those of the simple CRL/SAE blend. For the contained CRL-g-(MMA-co-St) blend, the maximum tensile strength (6.72 MPa) and the maximum elongation at break (1142.6%) were obtained when the content of SAE was 60% (occupied by the total dry weight). At the same content of SAE, the T-peel and lap shear strengths of the contact adhesive derived from the contained CRL-g-(MMA-co-St) blend were 5.3 N/mm (canvas to canvas) and 1.8 MPa (plywood to plywood), respectively. The grafted copolymer CRL-g-(MMA-co-St) showed a remarkable compatibilizing effect on the CRL/SAE blends by drastically improving their mechanical properties. 相似文献