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251.
平顶山市湛河水水质预报模型研究 总被引:1,自引:0,他引:1
运用随机理论--马尔科夫过程预报平顶山市湛河水质,并通过平顶山市湛河近十年的水质监测数据验证了模型的可靠性,对2000年前后湛河水质进行预报,为使2000年淮河流域水质变清,给平顶山市的管理层提供了一定的理论依据。 相似文献
252.
253.
To better understand the feeding and reproductive ecology of euphausiids (krill) in different ocean environments, lipid classes
and individual lipid components of four different species of euphausiids from Northeast Pacific (temperate species) and Southern
Ocean (Antarctic species) were analyzed in animals from multiple life stages and seasons. The dominant krill species in the
Northeast Pacific Euphausia pacifica and Thysanoessa spinifera, were compared to the two major Antarctic species, Euphausia superba and E. crystallorophias. Analysis comprised total lipid and lipid classes together with individual fatty acid and sterol composition in adults, juveniles,
and larvae. Antarctic krill had much higher lipid content than their temperate relatives (10–50 and 5–20% of dry mass for
Antarctic and temperate species, respectively) with significant seasonal variations observed. Phospholipids were the dominant
lipid class in both temperate krill species, while neutral storage lipids (wax esters and triacylglycerols for E. crystallorophias and E. superba, respectively) were the major lipid class in Antarctic krill and accounted for up to 40% of the total lipid content. Important fatty acids, specifically 16:0, 18:1ω9, 20:5ω3, and 22:6ω3, were detected in all four krill species, with minor
differences between species and seasons. Detailed lipid profiles suggest that krill alter their lipid composition with life
stage and season. In particular, larval Antarctic krill appear to utilize alternate food resources (i.e., sea-ice associated
organisms) during austral winter in contrast to juveniles and adults (i.e., seston and copepods). Lipid dynamics in krill
among krill in both systems appear closely linked to their life cycle and environmental conditions including food availability,
and can provide a more complete comparative ecology of euphausiids in these environmentally distinct systems. 相似文献
254.
255.
UV诱发的羟基自由基,引起了DNA互补碱对间的交联。本文论证了UV引起的互补碱对交联是UV诱发基因突变的主要根源。UV与化学致癌剂不同,可以引起双氢键AT对转化成叁氢键GC或CG对的点突变,这与腺嘌呤A在UV作用下转化成2-羟基腺嘌呤有关。本文采用高级半经验AM1方法,对UV诱发产生的羟基自由基在腺嘌呤8-位及2-位的羟基化反应,进行了计算探讨。证明在两个位置上的反应均经两步完成,反应的活化能较小并且焓变为负值、反应无论在动力学或热力学上均有利于发生。8-羟基腺嘌呤或8-羟基鸟嘌呤的存在,虽然是羟基自由基作用于DNA的标志性产物,但因其不影响小沟槽的氢键键合,很易被修复而不影响基因变异。但DNA双股中的2-羟基腺嘌呤碱或其互变异构体,则引起AT→GC或AT→CG的双氢键键合向叁氢键键合的突变。 相似文献
256.
Lee C Kim Y Nagajyothi PC Thammalangsy S Goung SJ 《Environmental science and pollution research international》2011,18(5):743-755
Introduction
The purposes of this study, as part of research projects for establishing the preservation environment of domestic cultural properties, are to identify the hazardous environmental factors which have a possibility to cause damages on long-term preservation of cultural heritage within the museum exhibition halls and the storages area, and to provide the basic data for the future establishment of preservation environment. 相似文献257.
The objective of this paper was to develop a mechanistic-based framework to explicitly incorporate the factors controlling the bioavailability, toxicodynamics and mode of action to enhance predictive ability of arsenic (As) toxicity to protect the health of farmed tilapia Oreochromis mossambicus. We linked the biotic ligand model and damage assessment model to develop a toxicokinetic model for elucidating the site-specific temporal changes of As bioavailability and to characterize how the fish regulate the metal toxicity. We built a bioavailability-mode of action-based growth toxicity model by linking a bioenergetic growth model and damage assessment model to predict how the As affects on the tilapia growth in the entire life span in site-specific field ecosystems. Here we show that the proposed model well describes the water-chemistry-dependent toxicokinetics and toxicodynamics variations of As to tilapia. We selected two local tilapia farms with different water chemistries located at southwestern Taiwan coast region to implement the proposed algorithm to predict the risk of As exposure. Results indicate that the growth toxicity of O. mossambicus in Taihsi is more sensitive than that in Peimen. We found that the effect of ion competition on the As bioavailability and their ecotoxicological effects on tilapia are more obvious in Taihsi comparing with that in Peimen. We suggested that the proposed bioavailability- and mode of action-based framework can be used to capture the biological response and regulation of tilapia to As exposures. It is applicable for a site-specific and long-term ecotoxicological risk assessment. 相似文献
258.
Valéria R. F. da Silva Sylvia F. Mitraud Maria L. C. P. Ferraz Eduardo H. S. M. Lima Maria Thereza D. Melo Armando J. B. Santos Augusto César C. D. da Silva Jaqueline C. de Castilhos Jamyle A. F. Batista Gustave G. Lopez Frederico Tognin João Carlos Thomé Cecília Baptistotte Berenice M. Gomes da Silva José Henrique Becker Juçara Wanderline Fernanda de Vasconcellos Pegas Gonzalo Róstan Guy Guagni dei Marcovaldi Maria Ângela G. dei Marcovaldi 《Environment, Development and Sustainability》2016,18(6):1541-1558
In the 35 years since its inception, the Brazilian National Program for the Conservation of Marine Turtles (TAMAR) has had great success in protecting the five species of sea turtles that occur in Brazil. It has also contributed significantly to worldwide scientific data and knowledge about these species’ biology, such as life cycles and migration patterns. TAMAR’s conservation strategies have always relied on a variety of environmental education and social inclusion (EESI) activities highly adapted to the socio-environmental evolving contexts of its 25 locations distributed across nine states. Diversity and flexibility are critical to enable timely and effective local responses to existing or potential threats to sea turtles. The intuitive, locally adapted, decentralized, and independent way EESI activities have been carried out have generated positive results in the resolution of specific and evolving local problems through the course of the project. This article brings EESI under the same conceptual framework that underlies its conservation approach by adopting an adaptive threat management framework to organize and qualify its educational and social inclusion interventions according to the main categories of threat addressed by TAMAR. 相似文献
259.
Fang S. Shi Jing Liu Lei Zhang Ju X. Liu 《Journal of environmental science and health. Part. B》2016,51(10):715-721
In this study, 2-chlorophenothiazine was used to synthesize a hapten for production of monoclonal antibody. The obtained monoclonal antibody showed high crossreactivities to chlorpromazine, promethazine and perphenazine, and showed low crossreactivities to acepromazine and fluphenazine. After evaluation of three coating antigens, a heterologous competitive indirect enzyme linked immunosorbent assay was developed to determine the five phenothiazines in animal feeds and the residues of chlorpromazine, promethazine and perphenazine in meat. The crossreactivities to the five analytes were in a range of 2.4%–98%. The limits of detection for the five drugs in feeds were in a range of 0.1–3.0 μg g?1, and that for chlorpromazine, promethazine and perphenazine in meat were in a range of 0.5–0.8 ng g?1. Their recoveries from standards fortified blank samples (chicken, pork and feeds) were in a range of 74.1%–96.5% with coefficients of variation of 6.4%–15.1%. Therefore, this method could be used as a rapid screen tool to determine phenothiazine drugs in animal feeds and animal derived foods. 相似文献
260.
聊城市城区河湖水中Hg、As浓度分布特征及健康风险评价 总被引:1,自引:0,他引:1
为了解聊城市城区河湖水中Hg、As浓度分布,于2010年12月19日采集、分析了20个表层水样中Hg、As浓度,并采用美国环境保护署推荐的健康风险评价模型对其进行了初步评价.结果表明:城区河湖水中Hg、As的质量浓度分别为0.016~0.366、0.494~23.438 μg/L,各主要河湖水中Hg的平均浓度大小为周公河>东昌湖>小运河>徒骇河;As的平均浓度大小为周公河>徒骇河>小运河>东昌湖;东昌湖Hg浓度超过《地表水环境质量标准》(GB 3838-2002)的Ⅲ类水标准值,超标率为71.4%.各主要河湖水中Hg、As浓度的空间分布差异显著,Hg主要来源于大气沉降和沿岸生活污水的排放,As主要来源于工业废水,两者均受到上游来水的影响.As通过饮水途径产生的健康风险值在10-6~10-4 a-1,是Hg的103~106倍,高于部分机构推荐的最大可接受风险水平(1.0×10-6 a-1).建议有关部门应加强对聊城市城区河湖水中Hg、As的监测和环境风险管理. 相似文献