麻痹性贝毒PSP在紫贻贝体内的累积、转化与排出

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%。     

数字河流数据的自动综合

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。     

Use of Magnet Technology for Phosphate Elimination from Municipal Sewage

The present report describes the set-up and first operation results of a novel carousel magnetic separator. This carousel magnetic separator is suitable for continuous separation of magnetized particles from water. Continuous operation is achieved by a segmented rotating separation matrix. This matrix also allows the use of low-cost permanent magnets, by means of which magnetic fields of up to 0.5 T can be generated without energy consumption. The suitability of a first prototype of this carousel magnetic separator was tested for elimination of magnetite-containing iron phosphate and iron hydroxide flocs. These flocs result from conventional precipitation/flocculation of municipal sewage with FeCl₃ and the addition of magnetite particles generated by wet-chemical processes. First results demonstrate that the carousel magnetic separator can reduce phosphate concentrations of up to 14 mg/L PO₄^3–-P in the inlet to below 1 mg/L PO₄^3–-P in the outlet at filtration rates of about 40 m/h. Magnetite dosage in the range of 50 mg/L affects phosphate precipitation positively via a slight reduction of the precipitant volume. However, the total amount of chemicals required for phosphate elimination is increased by the substances needed for magnetite production. Therefore, a further reduction of magnetite dosage must be achieved.     

栉孔扇贝对无机砷的富集与排出特征研究

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...     

走时反演的一种非迭代算法

本文给出了用剥皮法反演地下介质速度的思想,并将某些特定路径的直射线用于反演井间速度,并在此基础上对算法进行了探讨,避开了一般的迭代算法而用消元法,这种方法具有简捷、直观的特点,也指出了该方法的不足:误差的传递积累。在文章的最后,讨论了该方法的实际应用价值及理论试算,得到了比较好的效果,每个模型的处理时间不超过五分钟.     

军事交通图数据库支持下的自动制图综合研究

本文以1:50万军事交通图数据库为基础,探讨并研究了数据库支持下的自动制图综合的理论,方法和实施过程:重点研究了地图内容的选取、线状要素的化简和重迭要素的移位问题;尤其是对图形要素的移位,做了较为详细的分析,提出了检查线状要素之间图形重迭的方法及自动移位的具体措施,并给出了用于程序运行的一些详细算法。     

恶意软件的特征、危害性及其防范与清除方法

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。     

Organotin accumulation in an estuarine food chain: comparing field measurements with model estimations

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.     

SOMATOM PLUS型CT故障分析及排除

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。     

Transfer and distribution of lead in the asteroid Asterias rubens following ingestion of contaminated food: a radiotracer study

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.