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981.
Marine organisms constitute unlimited resource of bioactive substances due to their high biodiversity and represent a valuable source of new compounds. This study optimized the alkali-extraction conditions and antioxidant activities of soluble polysaccharides from the body wall of Sipunculus nudus. The effects of solid-liquid ratio, extraction duration, extraction temperature, and alkali concentration on the yield of S. nudus polysaccharides (SNP) were examined, according to which the optimal combination of extraction parameters was obtained by an orthogonal test. The relative influencing importance of different extraction parameters on the yield of SNP followed the order as solid-liquid ratio > extraction temperature > alkali concentration > extraction duration. The highest extraction yield, 1.98%, was achieved under an optimal extraction condition: temperature 60°C, solid-liquid ratio 1:6 g mL?1, duration 5 h, and alkali (NaOH) mass fraction 6%. The in vitro antioxidant activities examination showed that extracted SNP under this optimized condition had strong power in reducing certain hydroxyl and superoxide radical scavenging abilities. The promising results showed that extracted SNP could be a potent natural antioxidant. 相似文献
982.
Xiujun Sun Biao Wu Liqing Zhou Zhihong Liu Yinghui Dong Aiguo Yang 《中国海洋大学学报(英文版)》2017,16(2):279-284
Melanin is one of the essential compounds in the pigments of molluscan shells. However, the effects of melanin on color variations in molluscs are largely unknown. Our previous study suggests that Yesso scallop Patinopecten yessoensis might contain melanin pigment in the dark brown shell. We therefore isolated melanin from the pigmented shells using hydrochloric acid method, and characterized the types of melanin pigments by spectrophotometry. The purified melanin, which was verified by spectrophotometry scanning and HPLC analysis, showed the typical characteristics of melanin absorption spectra and HPLC chromatograms. The contents of pheomelanin and eumelanin in pigmented shells, which were determined by the linear standard curve of melanin at 405 nm and 350 nm absorbance, were 48.23 ± 1.350 and 157.65 ± 5.905 mg, respectively. The present results indicate that the brown-pigmented shells of scallops comprise approximately 76.6% of eumelanin and 23.4% of pheomelanin, which supports the presence of eumelanin-rich pigment in scallop shells. Therefore, the combination of hydrochloric acid extraction and spectrophotometric quantification is a rapid and efficient method to isolate and quantify melanin in shells. This will facilitate the melanin studies related to shell color polymorphism and the selective breeding of bivalves with different shell colors. 相似文献
983.
Historically, Crescent City is one of the most vulnerable communities impacted by tsunamis along the west coast of the United States, largely attributed to its offshore geography. Trans-ocean tsunamis usually produce large wave runup at Crescent Harbor resulting in catastrophic damages, property loss and human death. How to determine the return values of tsunami height using relatively short-term observation data is of great significance to assess the tsunami hazards and improve engineering design along the coast of Crescent City. In the present study, the extreme tsunami heights observed along the coast of Crescent City from 1938 to 2015 are fitted using six different probabilistic distributions, namely, the Gumbel distribution, the Weibull distribution, the maximum entropy distribution, the lognormal distribution, the generalized extreme value distribution and the generalized Pareto distribution. The maximum likelihood method is applied to estimate the parameters of all above distributions. Both Kolmogorov-Smirnov test and root mean square error method are utilized for goodness-of-fit test and the better fitting distribution is selected. Assuming that the occurrence frequency of tsunami in each year follows the Poisson distribution, the Poisson compound extreme value distribution can be used to fit the annual maximum tsunami amplitude, and then the point and interval estimations of return tsunami heights are calculated for structural design. The results show that the Poisson compound extreme value distribution fits tsunami heights very well and is suitable to determine the return tsunami heights for coastal disaster prevention. 相似文献
984.
Dongyan Liu John K. Keesing Zhijun Dong Baoping Di Peter Fearns 《Marine pollution bulletin》2010,60(9):1423-1432
In the summer of 2008, the world’s largest green-tide occurred in the Yellow Sea, China. The hypothesized cause was the expansion of Porphyra yezoensis aquaculture along the Jiangsu coastline and the re-occurrence of a green-tide in 2009 was predicted. In this study, satellite and field images showed the formation of the June 2009 green-tide which again originated from the Jiangsu coast. The responsible species, its source and biomass accumulation were studied to support the previous hypothesis. Morphological and phylogenetic analysis demonstrated the homology of Ulva prolifera in the 2008 green-tide with the U. prolifera from P. yezoensis aquaculture rafts. About 91-505 kg/ha of U. prolifera was attached to the P. yezoensis aquaculture rafts and a total biomass of 4956 tonnes was estimated during the harvesting of P. yezoensis. This is sufficient to seed a bloom when they are dislodged from the rafts as a result of harvesting practices. 相似文献
985.
Remarkable progress has been made in electromagnetic (EM) techniques as applied to the petroleum industry in instruments,
data acquisition, and processing and interpretation in China. Included here is equipment, such as high-power Controlled Source
EM (CSEM) acquisition systems, acquisition methods, such as the three dimensional small-bin Continuous Electromagnetic Array
acquisition method, Time and Frequency Domain Controlled Source Electromagnetic, Borehole-to-surface Electromagnetic technique
and marine magnetotelluric method. Data processing methods, such as fast three dimensional inversion using nonlinear conjugate
gradients, and data interpretation methods, like Induced Polarization and Resistivity anomalies for hydrocarbon detection,
are also included. These new techniques have been applied in petroleum survey and many cases are in complicated areas. They
have successfully served the investigation of deep igneous rock reservoirs, and prediction of potential hydrocarbon targets.
The cases indicate that electromagnetic techniques can help seismic survey to effectively detect hydrocarbon reservoir and
remarkably improve drilling successes. 相似文献
986.
探索了地震科技信息工作与地方社会经济发展的内在联系及其作用。21世纪是现代化进程明显加快、经济迅速腾飞的时代,在江淮大地上掀起了以城市为龙头的、壮大工业经济、强化县域经济发展热潮。大发展、大建设、大环境的工作思路及东向发展战略,为地震科技信息工作提出了冷思考。如何搭上安徽"三大推进"的快车,是地震科技信息工作融入安徽经济发展的新起点。 相似文献
987.
988.
区际资本流动与区域发展差距——对中国银行间信贷资本流动的分析 总被引:3,自引:1,他引:2
一国经济发展初期,区际资本流动通常是导致区域发展差距形成、扩大的重要原因--资本往往从发展条件较差的地区流向发展条件较好的地区,从而产生“好者更好、差者更差”的马太效应。银行间信贷资本流动是区际资本流动的重要形式。本文通过构建计量方法对中国区域发展差距扩大阶段(1978-2003 年) 银行间信贷资本的区际流动方向进行测度,并分析其成因。计量结果发现,存在区际间信贷资本流动的年份,资本并未从发展条件较差的中西部地区流向发展条件较好的东部地区,而呈现相反的流动。这表明银行间信贷资本的区际流动至少在一定程度上缩小而不是扩大了区域发展差距。进一步分析发现,政府对信贷的管制以及市场环境的变化分别导致了1994年以前以及1994 年以后的银行间信贷资本流动。 相似文献
989.
用GPS位移场进行中小区域变形分析方法探讨 总被引:1,自引:1,他引:0
因局部区域相对全球框架不可避免地存在整体刚性平动分量,常影响对局部范围内地壳相对变形量级与特征的判读.对分离局部整体刚性平动分量的方法进行了探讨,通过实例分析认为,对京津地区28个GPS连续观测站给出的位移速率场,整体平移法和欧拉矢量法都能得到较好的效果,但相比之下,对于类似的中小区域,整体平移法更加简单明了. 相似文献
990.
针对当前国土资源所规范化建设中出现的科室业务衔接过程中的种种问题,就如何明确科所责权、完善机制,全面提升科所业务水平,提出了"一对一"业务指导、通过"收(退)件登记卡"完善管理机制、制定不同行政许可事项工作程序流程图等措施。 相似文献