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排序方式: 共有440条查询结果,搜索用时 31 毫秒
431.
Environmental Science and Pollution Research - This study investigated the occurrence of selected metals and metalloids (As, Cd, Cr, Cu, Hg, Ni, Pb, Zn) in radio-dated sediment cores from a coastal...  相似文献   
432.
Journal of Polymers and the Environment - In this work new biodegradable composite materials based on poly(butylene-adipate-co-terephthalate) (PBAT) reinforced with water-soluble calcium-phosphate...  相似文献   
433.
Journal of Polymers and the Environment - Grape pomace, as by-product of wine making, is a source of polyphenols, fibers, fatty acids, metals, and organic acids, which could be used as raw...  相似文献   
434.
Using interdisciplinary field research in the Usa Basin, northeast European Russia, we compared local inhabitants' perception of environmental problems with chemical and remote-sensing signatures of environmental pollution and their local impacts. Extensive coal mining since the 1930s around Inta and Vorkuta has left a legacy of pollution, detected by measuring snowpack, topsoil, and lichen chemistry, together with remote-sensing techniques and analysis of lake water and sediments. Vorkuta and its environs suffered the worst impacts, with significant metal loading and alkalization in lakes and topsoils, elevated metals and cations in terricolous (reindeer) lichens, and changes in vegetation communities. Although the coal industry has declined recently, the area boasts a booming oil and gas industry, based around Usinsk. Local perceptions and concerns of environmental pollution and protection were higher in Usinsk, as a result of increased awareness after a major oil spill in 1994, compared with Vorkuta's inhabitants, who perceived air pollution as the primary environmental threat. Our studies indicate that the principal sources of atmospheric emissions and local deposition within 25 to 40 km of Vorkuta were coal combustion from power and heating plants, coal mines, and a cement factory. Local people evaluated air pollution from direct observations and personal experiences, such as discoloration of snow and respiratory problems, whereas scientific knowledge played a minor role in shaping these perceptions.  相似文献   
435.
- DOI: http://dx.doi.org/10.1065/espr2006.01.014 Background, Aims and Scope Triazole-derivatives are potent antifungal agents used as systemic agricultural fungicides and against fungal diseases in humans and domestic animals. They act by inhibiting the cytochrome P-450 conversion of lanosterol to ergosterol, thus resulting in faulty fungal cell wall synthesis. Some data have been published about the teratogenic activity of triazoles on rodent embryos: Hypoplasias, abnormal shape, agenesis of the branchial arches, for example, were reported as typical induced malformations. Unfortunately, no data are available on the embryotoxicity of these compounds in amphibians, despite the increasing concern among the scientific community about the phenomenon of global amphibian population declines. The aim of the present work is to evaluate the embryo-lethal and teratogenic potentials of Triadimefon (FON), a triazolederivative widely used as an antimycotic in agriculture, by the test FETAX (Frog Embryos Teratogenic Assay, Xenopus) with particular attention being paid to the analysis of branchial arch malformations. Methods Xenopus laevis embryos were exposed continuously from stage 9 to increasing concentrations of FON and analyzed at stage 47 for mortality and teratogenicity (group I) to determine the median lethal (LC50) and teratogenic (TC50) concentrations. Another two pools of larvae were exposed to FON for a 2 hour period at early gastrula (Group II) or neurula (Group III) stages to verify which period of development is the most sensitive to FON. The malformations observed were further investigated by histological section and cartilage staining with Alcian blue. Results and Discussion The assay has estimated LC50 and TC50 values of 63.8 μM and 2.73 μM, respectively; the resulting TI (Teratogenic Index = LC50/TC50) value of 23.4 has underlined the very high teratogenic risk associated with this compound. Neurulation was more sensitive to FON exposure than gastrulation, since the TC50 estimated values for group III (neurula exposed) specimens was 7.6 times lower than those of group II (gastrula exposed). Interestingly, for each group analyzed, 100% of malformed embryos showed alterations at branchial arch derived cartilages: Anterior cartilages were reduced, missing, fused or incorrectly positioned while gill cartilages were altered only in the most severely affected specimens. In some cases these malformations were associated with hyperpigmentation. Our results support the hypothesis that FON can interfere with Neural Crest Cell (NCC) migration, since craniofacial components and melanophores are derived from neural crest material. Conclusion In conclusion, our data show Triadimefon to be a potent teratogen able to induce specific craniofacial malformation in Xenopus laevis embryos, probably interfering with the NCC migration into the branchial mesenchyme. These results are also interesting for ecotoxicological reasons as FON, as well as other pesticides, are likely to be present in water systems near agricultural or urban areas which may serve as habitats for developing amphibians and fishes. Recommendation and Outlook Our results are in agreement with the data obtained on in vitro cultured rat embryos suggesting that the FON mechanism of action involves strongly conserved molecules. The choice of Xenopus laevis as the model organism allows us to extend the toxicological and teratological observations to a molecular level, in order to search for novel genes regulated by FON exposure.  相似文献   
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Environmental Science and Pollution Research - Pethoxamid is chloroacetamide herbicide. Pethoxamid is commonly used to kill different weeds in various crops. Pethoxamid can leach in the water and...  相似文献   
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439.
Journal of Polymers and the Environment - Bio-based non-isocyanate poly(hydroxyurethanes) (NIPUs) have recently gained significant interest due to increasing awareness of the health and...  相似文献   
440.
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