A Comparison of Growth Biomarkers for Assessing Sublethal Effects of Cadmium on a Marine Gastropod, Nassarius festivus     

K. T. WO  PAUL K. S. LAM  RUDOLF S. S. WU 《Marine pollution bulletin》1999,39(1-12):165-173

The effect of cadmium on the growth of an intertidal marine gastropod, Nassarius festivus, was investigated using a number of biomarkers namely conventional measurements in terms of increase in shell length or body weight, scope for growth (SfG) and RNA/DNA ratio. After eight days of cadmium exposure, the no observable effect concentration (NOEC) and lowest observable effect concentration (LOEC) for the rate of increase in wet weight were 1.00 and 1.38 mg/l, respectively, while those for shell length did not show any significant difference from the control until day 16. After 16 days of cadmium exposure, the LOEC for both shell length and wet weight measurements was 0.22 mg/l. The 8-day SfG test was sensitive to cadmium stress, showing a significant decrease at 0.16 mg/l cadmium when compared to the control. The NOEC and LOEC of RNA/DNA ratio determination were 0.52 and 0.93 mg/l, respectively. An assessment based on sensitivity and technical complexity suggests that Scope for Growth is the most sensitive growth biomarker, followed by the RNA/DNA ratio, and then the conventional growth measurement based on shell size and body weight.  相似文献   

深部地震资料的处理和解释方法   总被引：9，自引：1，他引：8  

徐明才  高景华 《物探化探计算技术》1999,21(2):151-158

深部地震资料的处理类似于油气地震资料,但也有其自身的一些特点。在水平叠加处理前后,分别使用强有力的去噪和归位处理技术是获取高质量深部地震剖面的保证。在深地震时间剖面上,强能量条带的分布是大地构造格架的反映。综合测区重磁电等物化探资料进行解释,有利于提高解释精度和进一步探讨造山带的构造演化  相似文献   

K/T界线铂族元素丰度异常与地外撞击事件   总被引：9，自引：0，他引：9  

马配学  高洪林  侯泉林 《地球科学进展》1999,14(1):24-30

遍布全球的Ｋ／Ｔ界线粘土层不仅存在着铱的丰度异常,其它铂族元素的含量也异常高,并且基本上保持着类似与地外物质中的丰度分布模式,实验表明,在粘土层中铂族元素主要呈可交换离子相和难溶金属相的形式存在在,而在硫化物和硅酸盐相中的含量却很低,这与铂族元素来源于地外物体撞击的成因解释是一致的。  相似文献   

Internet 下多数据源、超媒体空间信息的分布式调度与管理   总被引：12，自引：0，他引：12  

韩海洋  黄建明  龚健雅  袁相儒 《武汉大学学报(信息科学版)》1999,24(3):08

在综述当代Ｉｎｔｅｒｎｅｔ ＧＩＳ各种实现模式基础上,提出了多数据源、超媒体空间信息的分布式管理与可视化调度的策略,使各种纷繁芜杂的空间信息相互协调为有机联系的整体,从而实现了空间信息的分布式处理和信息共享。  相似文献   

GIS中多用户环境下数据共享一致性问题研究   总被引：1，自引：0，他引：1  

朱欣焰  李德仁 《武汉大学学报(信息科学版)》1999,24(4):317-320

讨论了GIS中多用户环境下数据一致性问题,着重研究了由于某个用户修改其他用户已读数据所产生的不一致以及由于用户UNDO/REDO后产生的不一致。对于前者,本文提出了一种“通知-重读”法。  相似文献   

应用中间件技术的土地管理信息系统的研究     

王喜春  边馥苓  何勇 《武汉大学学报(信息科学版)》1999,24(4):331-335

介绍了中间件技术原理,说明了SDE在系统中的工作原理,并以南海市国主管理信息系统的设计与实现为例,介绍了应用中间件技术的GIS的研究与实践。  相似文献   

Primary Product Distributions from the Reaction of OH with m-, p-Xylene, 1,2,4- and 1,3,5-Trimethylbenzene     

D. F. Smith  T. E. Kleindienst  C. D. McIver 《Journal of Atmospheric Chemistry》1999,34(3):339-364

A study was conducted to examine the OH-initiated degradation products of the four title compounds in the presence of sub-part-per-million levels of NO_x. The oxidation was conducted in a dynamic reactor to minimize the conversion of the aromatic compounds. The experiments were designed to represent reaction pathways that occur in the atmosphere at ambient NO₂ concentrations. A wide range of ring-retaining and ring-cleavage products having widely varying yields were measured during the study. For m-xylene, the major primary products observed (with molar yields) were methyl glyoxal (0.40), 4-oxo-2-pentenal (0.12), glyoxal (0.079), and m-tolualdehyde (0.049). For p-xylene, the major primary products were p-tolualdehyde (0.103), 2,5-dimethylphenol (0.13), cis-3-hexene-2,5-dione (0.176), trans-3-hexene-2,5-dione (0.045), 2-methyl-butenedial (0.071), glyoxal (0.394), and methylglyoxal (0.217). Several other reaction products were measured at yields less than 3%. The primary products for OH + 1,2,4-trimethylbenzene were found as follows: methylglyoxal (0.44), glyoxal (0.066), cis-3-hexene-2,5-dione (0.13), trans-3-hexene-2,5-dione (0.031), biacetyl (0.114), 3-methyl-3-hexene-2,5-dione (0.079), and 2-methyl-butenedial (0.045). Six other (ring retaining) products were measured at yields less than 3%. The primary products for OH + 1,3,5-trimethylbenzene were methylglyoxal (0.90), 3-methyl-5-methylidene-5(2H)-furanone (0.1), 3,5-dimethyl-3(2H)-2-furanone (0.1), 3,5-dimethyl-5(2H)-2-furanone biacetyl (0.08), and 2-methyl-4-oxo-2- pentenal (0.05). Three other products were detected at molar yields less than 5%. In some cases, the yields for the ring fragmentation products could only be based on calibrations from surrogate compounds. Yields for several of the unsaturated dicarbonyl compounds have not been reported previously while yields for methylglyoxal, glyoxal, and biacetyl are largely consistent with previous reports. Some of the primary furanone products are the identical to those reported as secondary products in aromatic systems.  相似文献   

Retrievals of rain-rate over oceans from ssm/ i data using som model     

Bian Jianchun  Chen Hongbin  Sun Haibing  Yang Peicai  Lu Daren  Zhou Xiuji 《大气科学进展》1999,16(3):355-360

1.IntroductionOverthepasttwentyyears,anumberoftheoreticalandexperimentalworkhasbeencarriedoutontheretrievalsofrain--ratefromthespace--bornemicrowaveradiometers.Inrecentyears,manyalgorithmshavebeendevelopedtoretrieverain--ratefromtheSSM/Idata(Barrettetal.,1994;Ebertetal.,1996;Ferraroetal.,1995andsoon).However,becauseofthecomplicatednonlinearrelationshipbetweenbrightnesstemperatures(BTs)andrain--ratewhichiscausedbyvariousphysicalprocesses,theretrievalresultsbystatisticallychasedalgorithmsare…  相似文献   

剪切带中矿化与非矿化地段流体——岩石相互作用差异性研究   总被引：3，自引：0，他引：3       下载免费PDF全文

魏俊浩  张德全 《地质科学》1999,34(4):473-484

以河南西峡石板沟金矿为例,选择了一条控矿剪切带,对其中成矿地段的近矿蚀变岩和非成矿地段糜棱岩进行了系统的采样,探讨了二者在流体-岩石反应及岩石质量平衡之间的差异性。研究表明,剪切带中矿化地段蚀变岩其岩石体积总是扩容的,非矿化地段糜棱岩在变形过程中体积是损失的。矿化地段蚀变岩活性元素(K、Na、Si)总体呈被带入趋势,非矿化地段糜棱岩活性元素总体呈迁出趋势,糜棱岩的流体岩石率(N_u为93.68—468.40)远大于蚀变岩的流体岩石率(Nc_(Ⅳ)^s为36.11-216.67),剪切带中常量元素与微量元素富集与损失是渗透性流体带入、带出,岩石的体积损失与扩容综合作用的结果。  相似文献   

西昆仑山甜水海钻孔氧化铁指标的R／S分析及其意义   总被引：17，自引：0，他引：17  

周厚云  李世杰 《冰川冻土》1999,21(2):136-140

运用Ｒ／Ｓ分析法,对经过等时处理的甜水海钻孔氧化铁３项指标ＦｅＯ、Ｆｅ２Ｏ３及其比值ＦｅＯ／Ｆｅ２Ｏ３进行了分析计算,其指标都存在明显的Ｈｕｒｓｔ现象,Ｈｕｒｓｔ指数Ｈ分别为：Ｆｅ２Ｏ３为０．７６,ＦｅＯ为０．８５,ＦｅＯ／Ｆｅ２Ｏ３为０．６５,它们都大于０．５。反映了该地区过去２０多万年来气候环境变化存在持续性。３者Ｈｕｒｓｔ指数存在差异的原因目前还不清楚,可能说明它们反映气候环境演化持续性强度  相似文献