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91.
本文针对北京城市建设面临的自然与人为灾害背景,简要论述了北京地震、水灾、火灾及“新致灾源”的历史及现状,强调开展首都圈灾害研究及减灾规划设计的重要性,并提出了系统的减灾方略及相应的管理构想。 相似文献
92.
The physiological responses of the acid-sensitive amphipod Gammarus fossarum exposed in situ to acid stress (pH4.5 and 5.5) and then transferred back to neutral water were investigated. Survival rate and haemolymph [Cl(-)] and [Na(+)] were assessed after 24, 48 and 72h of exposure in acidic streams and after a recovery period of 12, 24, 36, 48 and 60h. After 24h, exposure to slightly acidic (pH5.5) and strongly acidic water (pH4.5) led to a severe and significant depletion in haemolymph [Na(+)] and [Cl(-)] compared to organisms exposed in circumneutral water (pH7.3). However, after only a 12h-period of transfer back in neutral water and whatever the previous exposure time (24, 48 and 72h) in both slightly and strongly acidic water, haemolymph [Na(+)] and [Cl(-)] were equal or superior to the control level without associated mortality. In spite of this fast physiological recovery capacity, populations of G. fossarum living in streams undergoing episodic acid stresses were drastically affected thus, demonstrating the high acid-sensitivity of this species. We discuss the possible reasons of population regression and the absence of population recovery. 相似文献
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95.
Investigation on the interaction between triclosan and bovine serum albumin by spectroscopic methods
Jiali Gu Siyao Zheng Heng Zhao 《Journal of environmental science and health. Part. B》2020,55(1):52-59
AbstractMulti-spectroscopic and molecular docking methods were used to study the interaction between triclosan (TCS) and bovine serum albumin (BSA). The results indicated that the fluorescence quenching of BSA by TCS was due to the formation of TCS–BSA complex through static quenching. This result was also demonstrated by time-resolved fluorescence experiment. The binding constants and number of binding sites between TCS and BSA were 1.30?×?105 M?1 and 1.17 at 298?K, respectively. The thermodynamic parameters were studied in detail which suggested that hydrophobic forces and hydrogen bond played major roles in the TCS–BSA interaction. Moreover, the site marker competitive experiments and docking studies revealed that TCS could bind BSA into site I in subdomain IIA. All the results of UV–vis spectrophotometry, circular dichroism spectroscopy and synchronous fluorescence spectroscopy showed that interaction between TCS and BSA induced conformation changes of BSA. 相似文献
96.
循环载体生物过滤工艺融三相流化、悬浮曝气、移动接触等几种不同工艺于一体,具有独特的工作原理和工艺特征。动态实验结果表明,循环载体生物过滤工艺容积负荷高,耐冲击负荷能力强,处理效果好,是一种比较理想的生物处理工艺。 相似文献
97.
铁催化聚丙烯腈脱氮的研究 总被引:2,自引:0,他引:2
应用热天平研究了载铁聚丙烯腈的脱氮碳化行为,负载铁对PAN的稳定化和脱氮碳化均具有显著的催化作用,并在580-760℃范围内明显增加了N2形成速率。XPS和XRD对碳化过程中铁和氮化学形态变化的研究结果表明,铁催化反应机理可能是负载铁与吡啶氮作用形成中间体铁氮化物,后者进而分解释放出N2。 相似文献
98.
在浓度场基础上,利用总磷、总氮和COD三项指标的综合指数法,结合管理部门提供的资料,划分了滇不不环境保护功能区,给出了划分指标值及功能区划分图。 相似文献
99.
Eighteen species of marine phytoplankton from 9 algal classes were tested under axenic-culture conditions for their capacity to improve phototrophic-growth performance on glycine with increasing concentration of this amino-acid serving as sole nitrogen source. Whereas all these species showed poor-to-no growth on 0.5 mM glycine, 14 species manifested considerable gain in growth-rate and yield at higher concentration levels. The highest level tested (25 mM) was generally not inhibitory and produced the best yields in these cases. Some species (notably Skeletonema costatum) showed marked reduction in the adaptation-lag period with increased glycine concentration, but Chlamydomonas palla required a very long adaptation period, which was little affected by concentration. Dunaliella tertiolecta, Emiliania huxleyi and Chroomonas salina showed sharp (albeit elevated) concentration thresholds for efficient glycine utilization. Rhodomonas lens and two cyanophycean strains, Agmenellum quadruplicatum and Anacystis marina, appeared incapable of successful growth on glycine at all concentrations tested, while the rhodophyte Porphyridium marinum displayed marginal growth. The results were insufficient to draw taxonomically general conclusions on algal-class potential for glycine utilization, but they showed unequivocally that more than 83% of phytoplankton species from 9 algal classes can utilize glycine for growth if the appropriate substrate concentration is provided. 相似文献
100.
Dry weight and body composition of C, H and N were investigated in male and female Tisbe holothuriae Humes fed 7 artificial compound diets and a living algal diet (Nannochloris sp.) over the whole biological cycle. No correlation was found between the respective proportion of C, H and N in the food and in the copepod body. Food quality had a significant effect on dry weight. Carbon content varied between 35.35 and 42.32% of body dry weight in females, and between 25.10 and 26.84% in males. Nitrogen values were 9.11 to 10.00% and 6.79 to 6.99%, respectively, varying with different diets. The C:N ratio varied between 3.74 and 4.28 in females and between 3.70 and 3.87 in males. Some diets had a significant effect on this ratio. In some experiments, three different temperatures were tested using the same diet. Body dry weight was inversely correlated with temperature, but no clear relation appeared between C:N and temperature. C:N variations were directly related to C concentration and seemed independent of N concentration. It is suggested that C variations correspond to different levels in lipid content under different trophic conditions. The relation between elementary chemical composition and fecundity in T. holothuriae fed different diets is discussed. 相似文献