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抗菌肽是大多数生物体中均存在的阳离子型短肽,其构成了生物免疫系统的重要部分。抗菌肽具有广谱高效的抗菌性和细胞选择性,其独特的膜破坏杀菌机制不易引起病原体的耐药性突变,有望成为新一代控制病原体的有效"抗生素"。但天然抗菌肽的提取成本高、产率低且周期长,不利于大规模生产推广,所以依托化学合成方法合成抗菌肽及其模拟聚合物应运而生。该方法为抗菌肽的设计及合成提供无限可能。本文介绍了抗菌肽的来源、结构和其作用机理并对现有的抗菌肽合成方法进行综述,阐述了现今抗菌肽及类抗菌肽的研究进展以及抗菌肽组装体的应用,最后对抗菌肽及类抗菌肽的发展前景作了展望,为开发高效、低毒的"新一代"抗生素提供重要信息和策略。 相似文献
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以生物基来源的γ-氨基丁酸为原料,采用高温水解-减压精馏法制备了高纯度的生物基丁内酰胺(BBY);以BBY为原料,通过阴离子开环聚合,合成生物基聚丁内酰胺(BPBY)。采用傅里叶红外光谱(FT-IR)、核磁共振氢谱(1 H-NMR)、高效液相色谱(HPLC)、差示扫描量热分析(DSC)、生物质谱(BMS)、拉伸测试和老化降解实验等手段对BBY和BPBY的结构、纯度、热性能、力学性能和老化降解性能进行了研究,并与石油基聚丁内酰胺(PPBY)进行了比较。结果表明:精馏后BBY的纯度高达97.7%(质量分数),BPBY与PPBY具有相似的结构及相近的热学和力学性能,BPBY比PPBY降解得更快,30d内降解17.56%(质量分数)。 相似文献
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放射性核素迁移研究及进展 总被引:1,自引:0,他引:1
张志军 《广东微量元素科学》2005,12(3):5-7
系统和全面总结了近年来放射性核素迁移研究的主要方法、内容及部分研究成果,主要从以下四个方面进行论述:迁移规律、迁移模型、相关研究、难点及新技术关键,并指出了其不足和亟待解决的难点。 相似文献
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《中国药典》收载的发酵虫草菌粉产品的质量标准中,规定以鸟苷、腺苷、尿苷的含量作为评价相关产品质量的标准。但除此之外,还有许多其他的核苷类成分对发酵虫草菌粉质量控制的影响尚未被探讨。为探究发酵虫草菌粉及产品质控指标选择的合理性,采用超高效液相色谱-紫外检测法对19批发酵虫草菌粉及产品中9种核苷成分(尿嘧啶、胞苷、鸟嘌呤、尿苷、腺嘌呤、肌苷、鸟苷、胸苷、腺苷)进行了定量分析,建立了发酵虫草菌粉样品的指纹图谱,并结合统计学提供了一种分析指标性成分的方法。通过优化样品的提取方法,选择超声提取法制备19批发酵虫草菌粉及产品的供试液;采用Agilent Eclipse Plus C18色谱柱(150 mm×4.6 mm, 3.5 μm)进行色谱分析,以甲醇-水为流动相梯度洗脱,对方法的校正曲线、准确度、精密度、重复性和回收率进行了验证。结合对照品指认了指纹图谱中的9个核苷峰,并采用外标一点法测得了各核苷成分的含量。使用化学模式识别对指纹图谱中的共有峰进行分析,聚类分析和主成分分析得到了同样的分类结果:19批样品共分为5类,其中同一发酵虫草菌粉因工艺差异可分为2类,而心肝宝胶囊、百令胶囊、宁心宝胶囊则各单独分为1类。同时,使用主成分分析获得了各样品中的指标性成分,分别为尿苷、鸟苷、腺苷、腺嘌呤、尿嘧啶,并使用聚类分析再次进行确证,验证了指标性成分的合理性。 相似文献
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聚苯胺的化学合成及表征 总被引:4,自引:3,他引:4
本工作利用化学方法合成了具有较高电导率的聚苯胺.研究了聚合条件如反应介质的pH值,不同种类的酸及其浓度,氧化剂的用量对聚合的影响.用红外光谱、X-射线衍射、DSC等方法表征了所得的聚合物,并研究了该聚合物的掺杂反应. 相似文献
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Pretreatments (water-soaking, pre-mercerization, mercerization under a pressure of 15 bars and steam explosion) were used
to improve the accessibilities and reactivities of celluloses of bleached flax, hemp, sisal, abaca and jute pulps for the
synthesis of methylcellulose. Degrees of crystallinity were determined by X-ray Diffraction (XRD) spectra. The iodine adsorption
accessibilities of pulps were low and accessible fractions ranged from 1.3 to 5.2%. Accessible fractions in amorphous cellulose
were calculated in the 5–18% range. The accessibilities of these pulps were hemp pulp > flax pulp > sisal pulp > jute pulp > abaca
pulp. Fourier Transform Infrared (FTIR) spectra showed that mean hydrogen bond strengths were weakened and relative crystallinity
indexes were decreased by pretreatments. The accessibility and reactivity of the abaca pulp were improved by water soaking,
mercerization under 15 bars pressure, steam explosion and preliminary mercerization, of which steam explosion and pre-mercerization
were the best treatments. Species was the main factor for the accessibility and reactivity. 相似文献
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先采用均匀沉淀法制备出CuO—ZnO催化剂,然后以CuO—ZnO催化剂作为晶核采用水热合成法制备出CuO—ZnO/HZSM-5(氢型ZSM-5分子筛)复合催化剂.利用X射线衍射和氨程序升温脱附手段对复合催化剂进行表征,并应用于CO2催化加氢合成二甲醚的反应.研究结果表明,在相同的反应条件下,这种CuO—ZnO/HZSM-5复合催化剂与采用物理混合法制备出的复合催化剂相比具有更好的催化效果,不但提高了CO2的转化率、二甲醚的选择性以及二甲醚和甲醇的总选择性,同时还改善了催化剂的稳定性. 相似文献
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系列甘露糖醛酸寡糖的制备与鉴定 总被引:1,自引:0,他引:1
用酸降解法制备了系列甘露糖醛酸寡糖(聚合度2~8),并分析测定了寡糖的结构. 褐藻胶经部分酸水解,于pH=2.85处分级获得聚甘露糖醛酸. 继续用酸降解法降解聚甘露糖醛酸,经凝胶柱层析分离纯化,获得系列甘露糖醛酸寡糖. 用荧光标记糖电泳(FACE)对寡糖进行了分析,并用电喷雾离子化质谱(ESI-MS)、 核磁共振波谱(NMR)及红外光谱(FTIR)进行了结构表征.
本研究用酸降解法制备饱和甘露糖醛酸寡糖,用凝胶柱层析法分离获得系列聚合度的寡糖,为褐藻胶大分子构效关系研究和药物的筛选与发现提供了重要的基础资料. 相似文献
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The combustion kinetics of Göynük oil shale, polystyrene and several polystyrene-oil shale blends were investigated by thermogravimetric analysis in the present study. Experiments were conducted at non-isothermal conditions with a heating rate of 5, 10 and 20 K min?1 in the 298–1173 K temperature interval under an air atmosphere. Differential thermogravimetric data were analyzed by two different models. Effects of blending ratio of oil shale and polystyrene and heating rate on the combustion kinetics were investigated. Kinetic parameters were determined and the results were discussed. 相似文献
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《Analytical letters》2012,45(5-6):603-612
In the present study the possibilities of electrothermal vaporization inductively coupled plasma optical emission spectrometry (ETV-ICP-OES) for characterization of archaeological glasses were investigated. The objects of our research were fragments of a colorless late antique Roman flat window glass (fifth century A.D.) and colored medieval glass bracelets (eleventh–twelfth century A.D.) excavated in the region of Pernik (West Bulgaria). The finely ground glass samples were analyzed directly and CHF3 was used as evaporation and transport modifier. Dried aqueous standard solutions and certified reference materials with different matrix (glass, fly ash, and stream sediment) were used as calibration standards. No matrix effects were observed by the optimized conditions. Measurements were performed using common calibration curves obtained with all appropriate calibration standards and major, minor, and trace element concentrations were determined. ETV-ICP-OES analytical data were used to establish the type of glass, the fluxing agents, the typical coloring and decoloring elements, and the recipe norm. 相似文献
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采用溶胶-凝胶法制备了多孔氧化铝膜, 并通过DSC、TGA、SEM、N~2吸附和气体透过率测定等手段, 对膜的性能进行了表征。结果表明, 用这种方法制备的多孔氧化铝膜是一种均匀无裂痕和具有较窄孔径分布(约4nm)的膜材料。将此多孔氧化铝膜制成膜反应器后, 用于甲醇催化脱氢制甲醛的反应, 发现甲醇转化率比常规反应器有较大幅度的提高。同时首次尝试采用溶胶-凝胶法将催化活性组分直接负载到多孔氧化铝膜上, 从而得到了一种具有催化活性的多孔膜, 并考察了它的反应活性。文中对由这两种多孔膜及钯/陶瓷复合膜制成的反应器的特点进行了比较。 相似文献
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碳苷研究 V: 用Grignard试剂合成取代苯酚中酚羟基的保护及脱保护 总被引:1,自引:0,他引:1
本文报道了一些取代苯酚的合成, 并探讨了用Grignard试剂合成取代苯酚中酚羟基的保护及脱保护的问题. 利用苄基和甲基作为酚羟基的保护基, 对文献报道的切断醚键脱保护方法进行了评价. 找到了两种新体系能在更温和条件下切断醚键的方法, 指出了它们的适用条件. 实验结果符合硬软酸碱理论. 相似文献
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D. R. Papulova 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(1):146-151
Mean bond energies, bond dissociation energies, and other characteristics were considered for certain classes of organic (and
other) compounds. The state of numerical data was discussed, and these data were ordered in series of related molecules. A
methodology for calculating bond energies was developed. Numerical calculations were performed. Certain rules were considered. 相似文献