共查询到19条相似文献,搜索用时 109 毫秒
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本文研究芦荟甙和芦荟大黄素的提取和同时测定。方法:以无水乙醇为萃取剂,从芦荟叶片和渗出汁液中提取芦荟甙和芦荟大黄素;采用分光光度法,同时测定芦荟甙和芦荟大黄素含量,测定波长分别为360nm和440nm.结果:从芦荟汁液和芦荟叶片中提取得到芦荟甙和芦荟大黄素的含量分别为39.0%、3.47%和1.39%、0.814%.回收率为98.0~102.1%、97.0~101.5%.结论:芦荟汁中芦荟甙和芦荟大黄素含量较高,本文提出分光光度法同时测定芦荟甙和芦荟大黄素含量,方法简便,快速、准确。 相似文献
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本文主要介绍了芦荟的两类活性成分——蒽醌类化合物和芦荟多糖类物质,分别对其做了进一步的医疗价值分析,并综合了当今一些研究成果。同时也简单介绍了芦荟的药用价值。 相似文献
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建立反相高效液相色谱法同时测定洁康舒洗剂中大黄酸、大黄素和大黄酚含量的方法。采用反相高效液相色谱法。symmctry C18柱(3.9×150mm,5μm)流动相为甲醇—水—磷酸(80:20:0.1);流速为1.0mL·min-1;检测波长为432nm。大黄酸、大黄素和大黄酚的回归方程分别为:C1=7.3159×10-1+1.8966×10-5A,r=9994,C2=1.0513+1.5680×10-5A,r=0.9999C3=1.2260-1.4684×10-5A,r=0.9999三者分别在7.60~38.0μg·mL-1、1.75~8.75μg·mL-1、2.4~12.OOμg·mL-1范围内呈线性关系。平均回收率和RSD分别为98.02%、96.63%、97.05%和1.78%、1.20%、1.15%。该方法操作简便,测定结果准确可靠,可用于测定洁康舒洗剂中大黄酸、大黄素和大黄酚的含量。 相似文献
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目的建立脑脉通中大黄总葸醌含量测定方法。方法利用大黄蒽醌类化合物能与质量分数0.5%酸镁反应显色,在波长512nm处产生吸收,采用可见分光光度法测定脑脉通复方中的以游离型蒽醌计的总蒽醌的含量。结果以1,8二羟基蒽醌为对照品,测得脑脉通有效部位中总蒽醌的含量在10%以上,平均回收率为102.91%,RSD=0.97%。结论本方法简便、准确、重复性好,可作为脑脉通有效部位中大黄总蒽醌的含量测定方法。 相似文献
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目的:通过大黄浸膏多种精制工艺的比较,以总酚为指标成分,采用比色法测定指标成分,为大黄制剂前处理提供实验依据。方法:采用水/醇法、醇/水法、酸/碱法等不同工艺的组合,进行大黄浸膏的精制。结果:所得大黄浓缩膏通过指标成分的测定,选择最佳工艺。结论:通过指标成分的测定,采用含醇量达60%-含醇量达75%-加6倍量去离子水-含醇量达85%为最佳工艺。 相似文献
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建立UPLC同时测定决明子中橙黄决明素、大黄素、大黄酚和大黄素甲醚含量的方法,采用ACQUITY UPLCBEH-C18色谱柱(2.1 mm×50 mm×1.7μm),乙腈和0.1%磷酸水溶液为流动相,采用梯度洗脱,流速为0.6 mL/min,检测波长为284nm。结果表明橙黄决明素、大黄素、大黄酚和大黄素甲醚分别在3.002~30.02μg/mL、2.500~25.00μg/mL、10.430~104.30μg/mL和5.916~59.16μg/mL的浓度范围内均有良好的线性关系(r=0.999 9),回收率均大于95%,RSD均小于2%。该方法快速,准确,重现性好,可用于测定决明子中橙黄决明素、大黄素、大黄酚和大黄素甲醚的含量。 相似文献
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目的制定舒筋定痛片的质量标准。方法采用薄层鉴别法鉴别大黄,骨碎补;高效液相色谱法测定大黄素和大黄酚的含量。结果在薄层色谱中均能检出大黄、骨碎补;大黄素在o.0105~0.0840ug,大黄酚在0.0408~0.3264μg范围内呈良好的线性关系(r=0.9995,0.9999),回收率99.77%,RSD为0.43%。结论该方法准确、灵敏、重现性好,能有效地控制舒筋定痛片的质量。 相似文献
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以γ-[(2,3)-环氧丙氧]丙基三甲氧基硅烷(KH-560)为偶联剂将大黄素键合到层析硅胶上,制备大黄素键合硅胶抗菌材料(EBS)。采用红外光谱、元素分析和热分析进行结构表征。采用滤纸片法和搅拌涂布平板法,研究EBS对大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌、农杆菌的抑菌活性。结果表明,EBS中大黄素键合量为0.223mmol/g。EBS对4种菌均有良好的抑菌效果,当培养基中EBS的添加量为0.5%时,对大肠杆菌、农杆菌、枯草芽孢杆菌和金黄色葡萄球菌的抑菌率分别依次为58.01%、55.94%、45.25%和27.18%。同时初步探讨EBS的抑菌机理。 相似文献
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Based on the restraining effect that spatial filtering has on the frequency spectrum of a beam, from the small-scale focusing theory of Bespalov and Talanov (B-T theory) we derive an expression for the pinhole diameter of the spatial filter corresponding to the fastest growing frequency. Then, compared with the theoretical pinhole diameter of the spatial filter, the restraining effect of the spatial filter on a hot image with different pinhole diameters is numerically investigated. The numerical results show that, if the pinhole diameter is larger than the theoretical one, the hot-image intensity will remain steady; once the pinhole diameter becomes smaller than the theoretical one, the hot-image intensity will begin to decrease. Moreover, as the pinhole diameter decreases, a more prominent restraining effect can be obtained. But reducing the diameter of the spatial filter would lead to greater beam energy loss. The parameters of the spatial filter must be chosen to guarantee that the scheme fulfills the demand for low beam energy loss and a satisfactory restraining effect simultaneously. 相似文献
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In this study, the surface and internal strain response of a specimen subjected to the nitrogen gas tension test was examined. The effect of the restraining force acting on the cylindrical specimen due to the rubber “O” ring seal was also determined. It was found that the effect of the restraining force was vanishingly small, and that the specimen was uniformly deformed in the axial direction. The effect of moisture content was also studied, and was found to have a considerable influence on the results. It was concluded that the concrete specimen should be considered as a two-phase system, consisting of a solid phase and a fluid phase. 相似文献
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E. Smith 《International Journal of Fracture》1990,45(4):283-298
Several toughening mechanisms for cracks in brittle solids depend on the restraining effects of material elements that bridge the faces of a crack. A standard way of quantifying the toughening effect is to smear-out the restraining stresses provided by the individual bridging elements. The present paper, by using a very simple simulation model which allows for the discreteness of the system, together with a general force-law for the behaviour of an individual bridging element, shows that the smearing-out procedure is valid if the bridging elements are ductile; however, it can underestimate the toughening effect when the elements are brittle. 相似文献
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防屈曲支撑的外围约束体系的革新研究始终是其核心内容。该文提出了梭形空间桁架约束型防屈曲支撑(STC-BRB)的概念,并以BRB工程应用中的四榀桁架约束体系为例,研究了STC-BRB的静力承载力和抗震设计方法。STC-BRB采用与其弯矩分布图相似的梭形桁架作为外围约束体系,具有提高材料利用率及外形美观等特点,适用于高层建筑和空间结构设置外露BRB的工程应用。该文建立了STC-BRB梁单元模型,采用ANSYS有限元软件对其弹性屈曲性能、弹塑性承载力和滞回性能展开研究,分别给出了基于承载力型和耗能型BRB约束比门槛值的设计方法。研究STC-BRB弹性屈曲性能,基于弹性屈曲荷载的理论和数值计算结果,提出了弹性屈曲荷载的计算公式,给出了BRB约束比的表达式。基于变化约束比的STC-BRB算例的计算结果,分别对其单调轴压弹塑性承载性能和拉压循环荷载作用下的弹塑性滞回耗能性能进行分析,研究了STC-BRB的失稳模式、极限承载力以及滞回耗能能力,获得了STC-BRB承载型和耗能型的约束比门槛值,建立了承载力和抗震设计的基本计算理论和设计方法。 相似文献
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薄板敷设条形阻尼结构抑制结构振动已有一定的研究基础,其中包括阻尼材料、阻尼的结构尺寸以及基于声子晶体理论的周期条形阻尼结构等对抑制结构振动的作用。但是,目前针对周期性阻尼结构的研究多数集中在多周期平行条形阻尼结构,而对于条形阻尼左右交替偏斜的敷设方式,尚未有明确的提出与运用。本文针对条形阻尼的交替偏斜敷设方式抑制薄板声辐射特性进行了相关研究,证明了与传统条形阻尼平行敷设方式相比,条形阻尼交替偏斜敷设方式能更好地降低薄板声辐射,且其结构中相邻条形阻尼结构存在最优的敷设夹角。 相似文献
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E. Smith 《Engineering Fracture Mechanics》1984,19(4):601-604
In the transition regime plain strain crack propagation in ferritic steels proceeds by a combination of cleavage and ductile rupture processes, the latter being confined to ligaments that are parallel to the direction of macroscopic crack propagation. These ligaments rupture as the crack propagates, and it is generally accepted that they have a restraining effect on crack propagation, and also provide a major contribution to the arrest fracture toughness . In modelling the propagation and arrest phenomena, and in quantifying this restraining effect, it is tempting to average the effect of the discrete ligaments over a region behind the crack tip. The results of this paper's theoretical analysis justify the use of the averaging procedure. 相似文献
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Shinya Takahashi Keiji Suzuki Noriichi Itoh Yusuke Okawa Hiroyuki Kobayashi Takashi Olino 《成像科学杂志》2013,61(3-4):139-144
AbstractThe influence of the liming period in the manufacturing process on the chemical and photographic properties of gelatin was investigated. Three limed osseins soaked for various periods were prepared and gelatins zvere extracted from them. The impurity contents of the gelatins and the physical restraining properties decreased with prolonging liming periods. The impurity contents and physical retardance were also relative to the extraction order. The deionization treatment of gelatin decreased the impurity contents and the differences of restraining effect with extraction order. Furthermore, the fractionation of sample gelatins by use of gel permeation chromatography was applied to study the relationship to the molecular weight of impurity contents and amino acid composition, as affected by the liming period. 相似文献