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断电会令通风系统停止运行 ,导致鸡舍内二氧化碳积聚以及舍内温度升高 ,这常常对鸡带来灾难性后果。定期检查备用发电机是一项必须采取的措施。本文作者发明了一种系统 ,能使鸡在断电时保持舒适直到供电恢复时为止。 相似文献
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Effects of incubation temperature and developmental stage of microspores on polyhaploid production in three wheat cultivars‘Pavon 76′, ‘Kitt’, and ‘Chris’ and one triticale cultivar, ‘T81′, were studied using a one-step medium. Calli failing to differentiate on the one-step medium were placed on a medium containing 1 mg/l indole-3-acctic acid (IAA) and 2 mg/1 6-furfurylaminopunne (KIN). Anthers containing either early- or late-uninucleate microspores were incubated in dark at 26, 28 or 32°C lor 3 days prior to transfer to 26°C. Averaged over temperatures and microspore stages, frequency of calli and green plantlets were 8.9 % and 3.4 %, respectively, for wheat cultivar‘Pavon 76′, 8.4 % and 1.6 % for cultivar ‘Kitt’, 4.5 % and 0.25 % for cultivar ‘Chris’, and 2.9 % and 0.12 % for the triticale cultivar‘T81′. However, cultivar-by-developmental-stage interaction was significant for frequency of callus induction. Temperature had no significant effects on callus induction and plantlet regeneration. Anthers containing early-unmucleate microspores produced no polyhaploids. 相似文献
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Muthanna A. Al-Omar Behla H. Al-Ogaily Dhia A. Shebl 《Water, air, and soil pollution》1989,44(1-2):1-7
As a continuation of the National Pesticide Monitoring Program in Iraq, this work was carried out to study the distribution of organochlorine insecticide residues in sediments and water from the lower part of Diyala river, Iraq, where a large sewage treatment plant is located. Sediment and water samples were analyzed by gas chromatography and found to contain different levels of lindane, aldrin, dieldrin, heptachlor, heptachlor epoxide, chlordane and isomers and metabolites of DDT. High levels of these compounds were detected in water samples taken in April. No corelation with time was noticed in sediment samples. The highest and most frequet values were those of chlordane and DDT in sediment and water samples. It was difficult to assess the effect of the sewage treatment plant on water pollution with organochlorine residues. 相似文献
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肉鸡的生长受到舍内环境的巨大影响。使环境最佳化的第一步就是对实际的环境条件进行监测。然后将其与标准的或推荐的环境条件进行对比。这样就可以知道应该采取什么步骤来获取最佳的肉鸡性能。 相似文献
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Assessment of groundwater risk using intrinsic vulnerability and hazard mapping: Application to Souassi aquifer, Tunisian Sahel 总被引：5，自引：0，他引：5
Special attention has been paid to risk assessment in water resource management in arid and semi-arid regions like the Souassi aquifer, Tunisia. Risk assessment, using vulnerability and hazard mapping, is considered as a fundamental aspect of sustainable groundwater management. To determine the degree of risk affecting the study area, an attempt has been made to combine hydro-geologic parameters using the DRASTIC method and the hazard assessment by taking the product of the weighted hazard value (HI), the ranking factor (QN) and the reduction factor (Rf).All parameters used in this risk assessment were prepared, classified, weighted and integrated in a GIS environment. Data treatment shows that large areas in the Souassi aquifer can be classified as high or very high risk areas corresponding to pollution sources located in high vulnerability zones. The areas with low and very low risk are situated in the south, which could, consequently, be interesting for future development and long term planning of protective measures. Sensitivity analyses indicated that the removal of groundwater depth, net recharge and aquifer media parameters from the DRASTIC index, causes large variation in vulnerability assessment. Moreover, hydraulic conductivity and topography were found to be more effective in assessing aquifer vulnerability. Therefore, they should have higher weights than those assumed by the DRASTIC standard method, and contrary to the impact of the vadose zone parameter. The validity of the DRASTIC and the risk methods, verified by comparing the distribution of nitrates in the groundwater and the different vulnerability classes, shows a high similarity. 相似文献
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Locating high quality groundwater resources in semi-arid regions with growing population and agricultural development is an expensive undertaking. Simple susceptibility indexing method, based on vulnerability and quality index, can be used to facilitate this application. The GIS technique provides an efficient environment to reach this objective. The contamination susceptibility index was calculated by taking the product of the vulnerability index (VI) and the quality index (QI). The VI index was calculated using DRASTIC method to evaluate the hydrogeological characteristics of the Aquifer. The quality index calculation procedure, based on the water classification, was introduced to evaluate hydrochemical data. The susceptibility indexing method was applied in the Chebba-Mellouleche Aquifer, located in Eastern Tunisia. The results show a clear degradation of the water quality throughout the Aquifer. In addition, the susceptibility indexing map which incorporates hydrogeological and hydrochemical datasets reveals a similarity with areas of high anthropogenic activities. Thus, it is more realistic to estimate the groundwater contamination. The main aim of this study is to give an overview of the drinking and irrigation water quality in relation to the hydrogeological characteristics of the Chebba-Mellouleche Aquifer. This overview can form the basis for further investigations. 相似文献
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