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排序方式: 共有32条查询结果,搜索用时 15 毫秒
1.
以栉孔扇贝(Chlamys,farreri)为试验生物,应用生物富集双箱动力学模型,研究了暴露在不同质量浓度的As<'3+>溶液中,栉孔扇贝对无机砷的耐受性;通过对富集与排出过程中栉孔扇贝体内无机砷含量的动态监测及对检测结果的非线性拟合,得出栉孔扇贝富集无机砷的吸收速率常数(k<,1>)、排出速率常数(k<,2>)、生...  相似文献   
2.
麻痹性贝毒PSP在紫贻贝体内的累积、转化与排出   总被引:15,自引:2,他引:13  
于1998年9月在青岛鲁迅公园附近礁石区采集紫贻贝(Mytilus edulis),采用实验室培养的方法,初步研究了塔玛亚历山大藻(Alexandrium tamarense,ATHK)产生的麻痹性贝毒(Paralytic Shellfish Poison,PSP)在其体内累积、转化与排出的规律。结果表明,在累积实验阶段,紫贻贝内脏的和肌肉中的PSP毒素含量均随实验时间的延长而逐渐增加,累积实验结束时,平均每只贝体内的PSP毒素含量为13.40nmol,毒性水平为12.24ugSTXEq/100g,紫贻贝内脏中的毒素含量远远高于肌肉,内脏中PSP毒素占贝体内PSP毒素总量的97.5%。在8天的排出实验阶段,贝体内的PSP毒素总量呈下降趋势,实验结束时,PSP毒素共排除了约50%,每天排除率约为9%。  相似文献   
3.
数字河流数据的自动综合   总被引:2,自引:0,他引:2  
本文主要介绍了数据库中水系要素综合中河流的自动综合方法,尤其是对非结构化河网中河流的自动选取作了较为详细的论述,并通过数据库中一幅完整图幅的河流数据对文中介绍的自动综合方法进行了验证。  相似文献   
4.
环形伪影是CT设备中多见的伪影响之一,本文根据SOMATOMPLUSCT上环形伪影的直径,伪影的宽度伪影的位置和伪影出现的时间为依据,并结合PLUS机型DAS系统部分的具体结构,判断故障所发生的部位和原因,并且验证了所作的判断,消除了故障。  相似文献   
5.
This study investigated the effectiveness of a new packing material, namely mixed rice husk silica with dried activated sludge for removing H2S. Dried sewage sludge was collected from Putrajaya sewage treatment plant in Malaysia. Rice husk silica was prepared at temperature of 800°C, after acid leaching and mixed with dried sewage sludge to be utilized in a polyvinyl chloride filter. The system was operated under variable conditions of two parameters, different inlet gas concentration and different inlet flow rate. H2S was passed through the filter with one liter of the packing material. More than 99.96% removal efficiency (RE) with empty bed residence time (EBRT) of 90–45 s and 300 ppm inlet concentration was observed. However, the RE decreased to 96.87% with the EBRT of 30 s. The maximum elimination capacity (EC) of 52.32 g/m3/h was obtained with the RE of 96.87% and H2S mass loading rate of 54 g/m3/h, while at the RE of 99.96%, maximum EC was 26.99 g/m3/h with the H2S mass‐loading rate of 27 g/m3/h. A strong significant correlation between increasing of H2S mass loading rate and pressure drop was also detected (p < 0.01). Maximum pressure drop was 3.0 mm H2O after 53 days of operating time, the EBRT of 30 s, and 54 g/m3/h of H2S loading rate. These observations suggest that the mixture of rice husk silica with dried activated sludge is a suitable physico‐biological filter for H2S removal.  相似文献   
6.
Non‐uniform distribution of biomass and the accumulation of excess biomass at the inlet of a unidirectional flow biotrickling filter (UF‐BTF) may lead to severe operating problems including increasing airflow resistance in packed bed, clogging, and low contaminant removal efficiencies, even performance loss. Therefore, a flow‐directional‐switching biotrickling filter (FDS‐BTF) was designed to improve performance such as the maximum elimination capacity and elimination efficiency. Toluene was chosen as the unique carbon source for microorganism. The results indicated that the purification performance of FDS‐BTF was superior to UF‐BTF. The maximum elimination capacity of FDS‐BTF was up to 480 g/(m3 h), which was 17.1% higher than that of UF‐BTF. After a 50‐day continuous operation, FDS‐BTF attained the stable purification performance and the outlet concentrations of toluene could meet the emission standard with inlet concentrations ranging from 720 to 1100 mg/m3 for an empty bed residence time (EBRT) of 23.9 s. The average well color development in FDS‐BTF was higher than that in UF‐BTF. It indicated that FDS‐BTF could improve the metabolic activity, which may improve the uniform distribution of biomass along the length of packed bed. When two systems were shut down, 24 and 48 h, respectively, the time that FDS‐BTF and UF‐BTF needed to restore the former elimination efficiency after a shut down of 48 h were 3–4 and 9–10 h. These data indicated that the purification performance of FDS‐BTF was superior to UF‐BTF.  相似文献   
7.
在实验水温(28±2)℃条件下,以60mg/kg单剂量甲基睾丸酮对尼罗罗非鱼混饲口灌给药后,采用超高效液相色谱-串联质谱联用(UPLC-MS/MS)法测定尼罗罗非鱼肌肉中的药物水平,研究甲基睾丸酮在尼罗罗非鱼肌肉中的代谢及消除规律。结果表明,肌肉中药物浓度时间数据符合一级吸收二室开放模型,主要药代动力学参数达峰时间T(peak)为3.04h,质量浓度C(max)为33.331ng/g,消除半衰期T(1/2)β为23.073h。肌肉中甲基睾丸酮浓度24h内呈指数型下降,具有较高的消除速率,其后消除得较缓慢,消除方程符合C=46.18e0.101t。29d后罗非鱼肌肉中甲基睾丸酮水平在美国FDA的检测限0.8ng/g以下,给药120d后肌肉中检测不到甲基睾丸酮残留。  相似文献   
8.
恶意软件的特征、危害性及其防范与清除方法   总被引:2,自引:0,他引:2  
恶意软件已成为社会公害,其泛滥是继网络病毒、垃圾邮件后互联网世界的又一个全球性问题。本文简要介绍了恶意软件的特征及其危害性,指出了防范恶意软件的一些具体措施,列举了清除恶意软件的常用方法。  相似文献   
9.
A radiotracer technique using 210Pb was applied to quantify the transfer and distribution of lead in the asteroid Asterias rubens following a single ingestion of radio-labelled mussels under controlled laboratory conditions. Approximately 50% of the 210Pb accumulated by mussels in their soft tissues from seawater was transferred to the asteroid through the food pathway resulting in a transfer factor less than unity. Loss kinetics of 210Pb in the asteroid were best described by a two-component exponential model. A. rubens eliminated 56% +/- 5% of the ingested 210Pb in a few days while the remaining fraction (42% +/- 5%), was absorbed and eliminated very slowly. Following ingestion, 210Pb was accumulated in the pyloric caeca and the body wall with little radioisotope found in the coelomic fluid. Lead-210 was then transferred to the organic matrix of the body wall through the general body cavity via the coelomic fluid, and then to the skeleton. In this way, lead appears to be progressively eliminated from the organic matrix of the body wall while it is efficiently trapped in the calcite skeleton. The sequestration and retention of lead in the skeleton is considered as a detoxification process, but it also prevents lead transfer to higher trophic levels of the marine food chain since the skeleton is not digested by higher consumers. In addition, the skeleton of asteroids can be regarded as a bioindicator of long-term dietary lead contamination.  相似文献   
10.
The bioaccumulation model OMEGA (optimal modelling for ecotoxicological applications) is used to explore accumulation of organotins in the Western Scheldt food chain, consisting of herbi-detritivores, primary and secondary carnivorous fish and a piscivorous bird. Organotins studied are tributyltin (TBT) and triphenyltin (TPT) and the respective di- and mono-organotin metabolites. Empirical elimination rate constants are compared to model predictions for organic substances and metals. It is found that field bioaccumulation ratios are higher than predicted based on elimination kinetics relevant for organic compounds. The results indicate that uptake of organotins mainly occurs via hydrophobic mechanisms, whereas elimination may occur via metal-like kinetics. This results in very low elimination rates, which are comparable to model predictions for metals.  相似文献   
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