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691.
对脉冲阴极保护技术的起源,发展历史及应用现状进行了介绍。根据学者对Q235钢、40角钢等金属在模拟海水环境下进行的脉冲阴极保护研究,确定了影响脉冲阴极保护效果的主要参数为脉冲周期、占空比、脉冲幅值以及阳极距离等,分析得出了脉冲阴极保护技术的优点以及该技术推广所存在的限制和原因,并与传统直流阴极保护技术的保护效果进行比较,显示出脉冲阴极保护技术用于金属设备防护时的优越性,可使保护电位更均匀,保护距离更长,在同等保护效果下的能耗更低。分析了当前海水环境下船用铝合金的使用特点以及保护现状。结合脉冲阴极保护的特性和优点,根据传统的阴极保护理论以及双电层理论,分析并展望了脉冲阴极保护技术用于海洋环境下船用铝合金防护的可行性和应用前景。  相似文献   
692.
Because the lack of detailed study of biological decolorization in high salt dye wastewater, it is still difficult to evaluate the biological treatment on high-salinity dye wastewater. The experiments were carried out to study the salt-tolerant bacteria, which is useful in the treatment of high-salinity colored wastewater. Simulated wastewater containing 5-150 g/L salt (NaCI) and 50-2000 mg/L Reactive Brilliant Red K-2BP was treated with three salt-tolerant mixed cultures (CAS, TAS, DSAS), which were under a gradually acclimated procedure. With the increase of concentrations of salt and dye, the decolorization became low. The abilities of decolorization of dyes wastewater by three mixed cultures (CAS, TAS, DSAS) were studied, CAS and DSAS mixed cultures showed more active for the treatment of high-salinity colored wastewater than TAS mixed cultures. The results suggested that there might be a simple process for the high salt wastewater treatment, which could be incorporated into conventional activated sludge plants.  相似文献   
693.
制备了Aroclor1242,1248,1254和1260四种多氯苯标准样品,利用DB-1毛细管柱气相色谱/电子捕获检测器对样品进行了分析,根据相对保留时间确定了所分离的同系物及其百分含量。检验了各样品的均匀性和稳定性,并对样品进行了定值,计算了不确定值。国际比对结果良好。该PCBs标准样品可应用于PCBs的环境监测、污染控制、质量保证、质量控制和仪器校准等。  相似文献   
694.
城市现代化发展的生态防护研究——以南京市为例   总被引:4,自引:1,他引:4  
配合南京市总体规划的修订,研究城市现代化发展的生态建设途径。城市空间拓展应与地理生态背景相适用,生态防护网络是总体规划确定的三个圈层结构的组成部分,具有削减大气污染负荷,调节氧循环,改善城市环境的功能。  相似文献   
695.
Dong Zhang  Junda Lin 《Marine Biology》2007,150(4):639-645
Sex change in many hermaphrodite animals has been suggested to be environmentally determined, especially socially. To investigate whether sex change in the protandric simultaneous hermaphrodite shrimp Lysmata wurdemanni (Gibbes 1850) is socially mediated, two experiments were conducted in the laboratory between September 2002 and April 2004 using laboratory-cultured shrimp that originated from Port Aransas, Texas, USA. The size at sex change (from male to simultaneous hermaphrodite) in this shrimp is variable, with the minimum around 2.4 cm in total length (TL). Large shrimp (2.4–4.5 cm TL) still in the male-phase (MP) have been found in the wild and laboratory environments. This study tested the hypothesis that large MP shrimp delay changing to the euhermaphrodite-phase (EP) due to social control. In the first experiment, ten shrimp were raised in large (110-l) and small (20-l) containers to test the effect of habitat size/density on sex change. The percentage of shrimp changing to EP was significantly higher in the large container (low density) than in the small container after 60 and 120 days. But after 570 days sex ratios were the same, 2 MP:8 EP. In the second experiment, group composition was changed over time to simulate population recruitment and mortality. MP shrimp delayed sex change when EP shrimp were present. However, if group structure is stable, some MP shrimp may not change sex during their lifetime. Under certain demographic conditions, such as when postlarvae (PL) were added to (simulating recruitment) or EP shrimp were removed from (simulating mortality) a group, all old MP (from original PL) shrimp changed to EP. The response of old MP shrimp to simulated recruitment is faster than to simulated mortality. The present study confirms that social control affects the size and timing of sex change in L. wurdemanni. However, some MP shrimp never change sex suggesting that genetics might also play a role in the sex ratios of L. wurdemanni populations.  相似文献   
696.
比较二花脸和皮特兰猪在2h运输过程中血浆ACTH、皮质醇、胰岛素和T3、T4水平的动态变化模式,以分析内分泌激素变化的品种特征.选用雄性二花脸猪10头,皮特兰猪6头,体重达20kg时安装颈静脉瘘管,1wk后运输试验,运输过程中不同时间点采集血样,放射免疫分析法测定血浆激素水平.上车后两品种猪ACTH水平缓慢上升,60min后达到峰值,下车后15min恢复至基础水平,运输过程中ACTH水平及变化幅度均未表现显著的品种差异;运输前皮质醇水平二花脸显著高于皮特兰猪,上车后两品种皮质醇均迅速上升,出发后15min达到峰值,下车后15min均快速恢复至基础水平,运输过程中皮特兰皮质醇上升的幅度显著高于二花脸猪;两品种胰岛素水平上车后均呈下降趋势,二花脸胰岛素水平总体上显著高于皮特兰猪;T3水平在上车后也表现快速下降,无论是T3水平还是其变化幅度均不表现显著的品种差异;皮特兰猪上车后T4水平稍微下降而二花脸猪显著下降,皮特兰T4水平总体显著高于二花脸猪.运输应激伴随血浆ACTH和皮质醇水平升高,而胰岛素、T3和T4水平下降,皮质醇水平升高的幅度能够反映猪的应激敏感性.图1参25  相似文献   
697.
对城市生活垃圾半好氧生物反应器填埋技术与传统垃圾填埋技术进行了对比试验,由试验结果可知,半好氧生物反应器填埋技术可缩短填埋垃圾产酸时间,净化渗滤液,加速填埋垃圾稳定化进程.城市生活垃圾半好氧生物反应器填埋技术是中国中小城市垃圾填埋处理的发展方向.  相似文献   
698.
Dong D  Li Y  Zhang J  Hua X 《Chemosphere》2003,51(5):369-373
Measurements were made regarding the adsorption of lead, cadmium, copper, zinc and barium to freshwater surface coatings (biofilms and associated minerals), which were collected in Nanhu Lake in Jilin Province, PR China, in order to investigate the variability of adsorption capacities of these heavy metals mentioned in the above surface coatings. The adsorption of lead and other heavy metals to the biofilms was observed to decrease in the following order: copper, lead, zinc, cadmium, and barium. Generally, the values of Gamma(max) (the maximum adsorption, micromol/m(2)) increased with the standard electrode potential of metal elements used and were recorded as 166.7, 40.0, 29.4, 10.8, and 1.8 for copper, lead, zinc, cadmium and barium, respectively. The values of 1/Gamma(max) increased linearly with the decrease in values of the standard electrode potential of metal elements with a significant correlation (n=5, p=0.01) and increased linearly with the increase in values of covalent radius of metal elements with a significant correlation (n=5, p=0.05). This indicates that standard electrode potential and covalent radius were two of the principal characteristics of metals employed, causing the variation of lead and other heavy metal adsorption to the surface coatings.  相似文献   
699.
提出了一种新的TiO2/GeO2复合膜圆形光催化氧化反应器,研究了该反应器对经物化处理后的农药废水进行降解的过程。研究表明,光催化氧化的最佳条件是锌片镀TiO2/GeO2复合膜、pH=6.7、过氧化氢(H2O2)浓度为400 mg/L。并对其他氧化剂对该过程的影响进行了探讨。有机废水通过该反应器处理后,其COD值降为57mg/L。能使有机污染物全部降解为小分子无机物,废水达到国家一级排放标准。  相似文献   
700.
脉冲放电烟气脱硫脱硝技术研究进展   总被引:5,自引:0,他引:5  
综述了脉冲放电等离子体烟气脱硫脱硝技术的发展历史、研究现状、进展及其存在的问题。  相似文献   
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