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91.
杂交鲟(Sturgeon cartilage)软骨中硫酸软骨素的提取方法及分析鉴定 总被引:1,自引:0,他引:1
采用稀碱浸提、蛋白酶水解与三氯乙酸沉淀相结合脱蛋白的工艺,对杂交鲟软骨提取琉酸软骨素的方法进行了较系统的研究。综合考察各种影响因素,设计了正交试验对提取工艺参数进行了优化,并对产品的质量指标进行了检验。结果表明,最佳提取工艺参数为:碱提取时料液比为1:2.0,碱浓度为4%,碱提温度为40℃;胰蛋白酶的酶解温度为55℃,酶量为2%,酶解时间为10h,制备的硫酸软骨素为白色粉末,得率为28.9%,纯度为92.3%,蛋白质含量为2.59%,各项质量指标完全符合标准要求。与目前已报道的其他软骨素制备工艺相比较,该方法具有工艺简便,提取率高,产品纯度高的特点。光谱分析法结构鉴定结果表明它是一种软骨素肽,其主要成分为硫酸软骨素C。 相似文献
92.
Determination of Pesticides in Water by On-line Solid-phase Extraction and HPLC-DAD This paper describes an HPLC on-line procedure for the determination of 29 relevant pesticides in water by diode-array detection using a compact HPLC-system with integrated column-switching. The sample – 5 mL – is injected with a large volume injection system on a precolumn cartridge (RP-C18). Enriched compounds are eluted in frontflush mode by columnswitching to a microbore column and separated with a gradient water/acetonitrile. During desorption the precolumn cartridge is heated at 80°C resulting in a comparable efficiency to the separation with direct injection. The procedure is fully automated for continuous monitoring of drinking-, ground-, and surface water with low contamination levels. Sample preparation is limited to a filtration step with an anion-exchange membrane filter to reduce natural contaminations e.g. humic acids simultaneously. For a concentration of 50 ng/L, the signal to noise ratio varies from 3:1 (Ethidimuron) up to 25:1 (Chloridazon). The standard deviations compare to the standardized HPLC-method DIN EN ISO 11369; the recovery rates are 100% and reproducible. The method was successfully tested on ruggedness with several sequences from a monitoring program. The precolumn cartridge needs replacement after 100 sample injections. Finally, this method was coupled with a benchtop mass-spectrometer (electrospray mode) without changing the chromatographic conditions. With selected ion monitoring (SIM) selectivity and detection sensitivity could be improved considerably compared to DAD-detection. 相似文献
93.
Hugh H. Mills 《地球表面变化过程与地形》1992,17(8):739-754
The crater of Mount St Helens shows one of the world's highest known rates of mass wasting. On many summer days, rockfall is almost continuous, and many large rock and dirty-snow avalanches have travelled several kilometres from their sources on the crater walls. Since formation of the crater on 18 May 1980, talus cones exceeding 100 m in thickness have formed at the base of the unstable 600 m high crater walls. To estimate rates of erosion and deposition, a series of digitized topographic maps made from aerial photographs taken of the crater in 1980, 1981, 1983, 1986 and 1988 were analysed using a geographic information system. Between 1980 and 1988, 30 × 106 m3 of rock were eroded from the crater wall, representing a mean retreat rate of 2.1 m yr?1. To account for the volume increase that occurs when bedrock is transformed into scree, this volume is multiplied by 4/3; this provides an estimate of the rock-debris volume supplied to the crater floor of 40 × 106 m3. The actual volume of deposits that accumulated during this 8 year period, however, is 68 × 106 m3. The difference of 28 × 106 m3 is presumably the volume of snow intercalated between insulating layers of rock debris. Similar calculations for each of four time intervals between 1980 and 1988 suggest that wall erosion and thus talus accumulation rates are declining, but that rates will probably remain high for decades to come. 相似文献
94.
《Marine pollution bulletin》2014,88(1-2):388-395
Distribution of sedimentary mercury in the Southern Baltic was investigated. Sediment samples were collected from the Southern Baltic in the period from 2009 to 2011, and concentrations of sedimentary total mercury (average 102 ng/g, range 5.8–225 ng/g) and methyl mercury (average 261 pg/g, range 61–940 pg/g) were measured in the manner that the influence of both patchiness and seasonal changes were assessed. Moreover, sedimentary mercury extracted with organic solvent- the so-called organic mercury was also analyzed (average 425 pg/g, range 100–1440 pg/g). There is a statistically significant dependence between organic mercury and both methyl mercury and total mercury concentrations in the sediments. Methyl mercury contribution to total mercury varied from 0.12% to 1.05%, while organic mercury contributed to 2% of total concentration on average. The area studied, although mercury concentrations exceed threefold the geochemical background, can be regarded as moderately contaminated with mercury, and methylmercury. 相似文献
95.
96.
正Cesium as a kind of alkali metals has widely been used in catalysis,medicine,biology,magnetic fluid power and other high-tech fields(Liao and Yang,2012;Cao et al.,2011;Wang et al.,2011).Although there was abundant of 相似文献
97.
剧动式高速滑坡是一种大量存在于自然界中的地质灾害。本文以广家崖斜坡危岩体为例,对基岩滑坡的“临床聚能”和“启程弹冲加速效应”进行了理论分析和探讨。文中详细论证了斜坡岩体滑落破坏时所具有的“启程弹冲加速效应”,并提出了二维应力状态下的启程冲速度计算公式。 启程弹冲机理,主要是锁固段岩体内聚力作用和岩体聚集赋存弹性应变能释放的反应,弹冲速度与内聚力的大小有直接关系。岩体一旦剪断破坏,弹性应变能骤然释放,岩体表现出剧烈的弹性回冲,弹性应变能便瞬间转化为岩体滑动的弹冲动能。这便从理论上对高速滑坡提出了具有实际意义的新机理。 相似文献
98.
99.
采用超声波细胞破碎和索氏回流相结合的方法对马尾藻(Sargassum sp.)总脂质进行了提取,对提取过程中的超声波细胞破碎功率和时间、料液比、溶剂等关键因素进行了优化;对总脂质中的多不饱和脂肪酸进行了分离,并分析了马尾藻脂肪酸组成成分和含量。结果显示,总脂质的最佳提取条件为超声破碎功率80 W、破碎时间20 min、料液比(m/m)1:8、石油醚(60~90℃)为溶剂、85℃水浴回流8 h;总脂质最高提取率为1.77%,其中总脂肪酸平均含量为30.84%;总脂肪酸中共含有11种成分,多不饱和脂肪酸含量约占13.21%~14.60%;薄层色谱分离出2种多不饱和脂肪酸C18:2ω6和C20:4ω6。 相似文献
100.
Road markings are used to provide guidance and instruction to road users for safe and comfortable driving. Enabling rapid, cost-effective and comprehensive approaches to the maintenance of route networks can be greatly improved with detailed information about location, dimension and condition of road markings. Mobile Laser Scanning (MLS) systems provide new opportunities in terms of collecting and processing this information. Laser scanning systems enable multiple attributes of the illuminated target to be recorded including intensity data. The recorded intensity data can be used to distinguish the road markings from other road surface elements due to their higher retro-reflective property. In this paper, we present an automated algorithm for extracting road markings from MLS data. We describe a robust and automated way of applying a range dependent thresholding function to the intensity values to extract road markings. We make novel use of binary morphological operations and generic knowledge of the dimensions of road markings to complete their shapes and remove other road surface elements introduced through the use of thresholding. We present a detailed analysis of the most applicable values required for the input parameters involved in our algorithm. We tested our algorithm on different road sections consisting of multiple distinct types of road markings. The successful extraction of these road markings demonstrates the effectiveness of our algorithm. 相似文献