共查询到19条相似文献，搜索用时 234 毫秒
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本文利用蚕豆根尖微核技术监测剑江都匀市区河段水质的污染状况,测定6个断面水样的蚕豆根尖细胞微核千分率(MCN‰)及污染指数(PI),并进行F检测,结果表明,各断面水样均能引起微核率升高,桃溪园、枣园、水厂、彩虹桥、百子桥和文峰园断面的微核千分率分别为6.92‰、6.00‰、9.53‰、11.36‰、6.63‰、5.57‰,PI分别为2.06、1.79、2.83、3.38、1.97、1.66。按照污染指数划分标准,枣园、百子桥和文峰园断面的水质为轻度污染,桃溪园、水厂、彩虹桥断面水质为中度污染。 相似文献
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蚕豆根尖细胞微核试验监测甲基对硫磷污染研究 总被引：4，自引：0，他引：4
用蚕豆根尖细胞微核技术，监测甲基对硫磷对环境的污染，从1．13‰至3．77‰各浓度的甲基对硫磷诱导微核千分率都明显高于对照组． 相似文献
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应用蚕豆根尖细胞微核技术检测南淝河水质的研究 总被引：1，自引：0，他引：1
本文应用蚕豆根尖细胞微核技术对南淝河水质进行了检测,测定了南淝河6个水样点的蚕豆根尖细胞微核千分率(MCN‰)及污染指数(PI),并进行F方差检测.结果表明:各样点MCN%在3.92-7.78‰之间,高出对照组蒸馏水0.93-6.78‰.6个样点的污染指数为1.31-2.60之间,有3个采样点的PI值在2以上,达到中度污染.F方差分析结果表明,各样点之间的根尖细胞MCN%存在着极显著的差异(P＜0.01).南淝河部分区域水质存在着不同程度的污染. 相似文献
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为探索EM菌在淡水水质净化处理中的作用,以不同的EM菌液浓度（VEM/V污水为0‰、0.1‰、0.5‰、1‰、5‰）在有氧通风、常温条件下处理天心湖水样,通过测定湖水样处理前后的pH、SS、色度、COD和氨氨水平变化,评价EM菌对淡水水质的处理效果,研究结果表明：浓度为0.1‰的EM菌液处理对天心湖水的COD去除效果最佳;浓度为1‰的EM菌液对天心湖水的氨氮去除效果最佳;浓度为5‰的EM菌液处理使湖水COD、氨氮水平升高,水质反而受到污染.通过选择EM浓度、处理时间、处理温度三个影响因素,按L9（34）正交表进行正交实验,结果表明EM处理天心湖水的最佳工艺条件是：处理时间7d、处理温度30℃、EM浓度0.2‰,对COD的去除率达到36.52％;按上述正交实验最佳工艺条件进行验证实验,结果表明,对天心湖水中COD的去除率可达到35.47％,对生活污水处理COD去除率可达41.18％.本实验可为进一步研究EM在水质处理上的应用提供参考. 相似文献
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劳务输出作为一种产业,在企业经济结构中所占份额日趋增加,水电五局二分局在香港排污隧道工程劳务项目中,坚持以市场为导向,以管理为手段,以经营为目的,大胆实践,在劳务输出管理方面进行了成功的尝试。 工程概况及面临的问题 香港策略性污水排放计划第一期工程,主要是收集处理来自香港岛东部及九龙市区的住宅及工业污水。现有的七个基本污水处理厂,对收集的污水经过基本处理后,通过六条全长为 23.6公里,直径为 3.2～ 4.2米,最深为水平面以下 150米的地下污水隧道,输通到昂船洲污水处理厂集中处理。集中处理后的污水再由一… 相似文献
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用化工厂废水、皮革厂废水和该两厂的混合废水分别对水稻种子和蚕豆根尖进行处理,观察水稻种子发芽率及幼苗的生长状况,以及蚕豆根尖细胞的微核率、异形核率和有丝分裂指数等情况.结果表明：化工厂废水对水稻种子的发芽率及幼苗的生长均有极其显著的抑制作用;皮革厂废水及皮革厂与化工厂的混合废水对水稻的发芽率及幼苗生长的影响均不显著.工业废水能诱发蚕豆根尖细胞产生较高的微核率和异形核率.皮革厂废水61.20‰,两厂混合废水为34.34‰,化工厂废水为10.10‰;异形核率：化工厂废水为10%,两厂混合废水为5.16%皮革厂废水为1.38%;化工厂废水及两厂混合废水对蚕豆根尖细胞分裂具有明显的抑制和危害,皮革厂废水对蚕豆根尖细胞有丝分裂指数影响不显著.说明化工厂和皮革厂废水对农作物具有明显的细胞遗传毒性. 相似文献
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《邢台职业技术学院学报》2022,(1):54-60
我国属缺水型国家且水体和水环境污染严重,积极发展污水深度处理和再生水回用是缓解水资源紧张、实现可持续发展的必要条件。基于高效同步脱氮除磷工艺研究,以城市及近郊为例分析了地上式和地下式污水处理厂的优缺点,基于工程实际在地下式污水处理厂的基础上进行了常用工艺的综合经济技术性能的比选,给出了基于改良AAO工艺的污水深度处理和再生水回用的综合方案。研究成果的工程实施有助于缓解水资源紧张并推进城市及近郊地下空间的综合利用,为打造干净卫生的环保型公园式污水处理厂的建设和推广提供了借鉴和参考。 相似文献
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呼和浩特辛辛板污水处理厂10万吨／日二级处理已经运行了3年,我对该厂选用设备的优缺点已比较清楚,结合对国内外同类设备的了解和学习,对呼市地区将新建和扩建的污水处理厂设备选型提出自己的想法。 相似文献
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研究了几种食前处理方法以及存放时间对蔬菜中亚硝酸盐含量的影响.结果显示：（1）5‰白醋浸泡30min、1‰食盐水浸泡30 min、4‰洗洁精浸泡30 min能有效降低大白菜中亚硝酸盐的含量.大白菜的亚硝酸盐含量在6 h、12 h内不断上升.冰箱4℃条件下存放能够有效抑制亚硝酸盐含量的增加;（2）蔬菜随着放置时间的延长,其亚硝酸盐含量呈上升趋势,小白菜和黄瓜中的亚硝酸盐含量分别在存放30 h,24 h和18 h后达到最高. 相似文献
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以非洲菊粉红系为供试材料,以浓度为0.25‰、0.5‰、0.75‰、1.00‰、1.25‰的6个不同浓度羧化壳聚糖作为保鲜液,通过外部形态观察和生理指标的测定,研究羧化壳聚糖对非洲菊切花瓶插的保鲜效果。结果表明：羧化壳聚糖能有效减少瓶插过程的水分蒸腾,减缓pH值大幅度变动,保持花青素含量,维持细胞膜相对透性等,从而延长鲜切花寿命。0.75‰和1.00‰浓度羧化壳聚糖溶液对延缓非洲菊鲜切花衰老的效果最佳,其比清水对照延长三天瓶插寿命。 相似文献
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Stephen L. Thompson Christine Lotter Xumei Fann Laurie Taylor 《Journal of Science Teacher Education》2016,27(4):439-463
Researchers examined how an inquiry-based instructional treatment emphasizing interrelated plant processes influenced 210 elementary pre-service teachers’ (PTs) conceptions of three plant processes, photosynthesis, cellular respiration, and transpiration, and the interrelated nature of these processes. The instructional treatment required PTs to predict the fate of a healthy plant in a sealed terrarium (Plant-in-a-Jar), justify their predictions, observe the plant over a 5-week period, and complete guided inquiry activities centered on one of the targeted plant processes each week. Data sources included PTs’ pre- and post-predictions with accompanying justifications, course artifacts such as weekly terrarium observations and science journal entries, and group models of the interrelated plant processes occurring within the sealed terraria. A subset of 33 volunteer PTs also completed interviews the week the Plant-in-a-Jar scenario was introduced and approximately 4 months after the instructional intervention ended. Pre- and post-predictions from all PTs as well as interview responses from the subgroup of PTs, were coded into categories based on key plant processes emphasized in the Next Generation Science Standards. Study findings revealed that PTs developed more accurate conceptions of plant processes and their interrelated nature as a result of the instructional intervention. Primary patterns of change in PTs’ plant process conceptions included development of more accurate conceptions of how water is used by plants, more accurate conceptions of photosynthesis features, and more accurate conceptions of photosynthesis and cellular respiration as transformative processes. 相似文献
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Anna Mette Fuglseth Kjell Grønhaug Kurt Jörnsten 《Scandinavian Journal of Educational Research》2018,62(1):88-108
This paper reports on a study exploring master students’ ability to apply their knowledge when solving an internal pricing problem in a supply chain. Analyses of 33 negotiation progress reports and 8 recordings of discussions demonstrate that most of the students were not able to apply relevant concepts and models to guide their handling of the task. The main reason for the variability in performance was the significant differences in the students’ general problem-solving abilities. Most students did not perform a thorough task analysis or develop a solution strategy before they met for negotiations, and they did not keep track of their task performance. The implications for teaching are highlighted, and directions for further research are proposed. 相似文献
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Objective： To test the effects of corrective spectacles in hyperopic amblyopic children with heterophoria. Methods： Visual acuity, refraction and the amount of heterophoria on near （33 cm） fixation were measured before and after 3 weeks of spectacle-wearing in 30 hyperopic amblyopic children with heterophoria. The control group consisted of 20 emmetropic children age-matched to the patients. Results： Uncorrected eyes displayed hyperopic amblyopia accompanied by heterophoria. Corrective spectacles not only attenuated the hyperopia and amblyopia, but also changed the heterophoria to orthophoria. The amount of heterophoria before wearing spectacles was significantly different from that in emmetropic children; but after correction with spectacles, it was the same as that in the emmetropic controls. Conclusion： Correction with spectacles is effective for the treatment of heterophoria in hyperopic children with amblyopia. 相似文献
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Carlo Ambrogi Lorenzini Corrado Bucherelli Aldo Giachetti Giovanna Tassoni 《Learning & behavior》1990,18(2):191-198
The effect of tail-handling on exploratory behavior of the rat, measured as step-through latency in a well-lighted, two-box apparatus, was investigated. Male adult Wistar rats, aged 60 days, were employed in all three experiments. Experiment 1, in which the subjects were handled at different times after entering the goal chamber (0, 10, 30, 60, 300, and 600 sec), showed that immediate handling, relative to detention in the goal chamber (delay of handling) had an inhibitory effect on exploration. Experiment 2 showed that groups handled immediately after entering the goal chamber but then detained there for different durations all showed the same progressive inhibition of exploration. Experiment 3 showed that the inhibition of exploration (very long step-through latencies) due to tail-handling immediately after entering the goal chamber could be significantly decreased by further trials in which handling was delayed for a sufficient duration (30 sec or more). Handling is discussed as a stimulus that is aversive enough to elicit conditioned passive-avoidance responses (inhibition of exploratory behavior), although it is subject to rapid extinction. 相似文献
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为提高火电厂的整体运行效益,提出了基于分布式的PLC火电厂输煤控制系统设计方案.通过科学地控制火电厂输煤系统的供煤量和供煤时机,以提高煤炭的燃烧效率.重点阐述了基于西门子的PLC控制系统详细设计方案和分布式的PLC控制器联网及通信机制,在此基础上设计PLC控制程序,优化火电厂输煤策略,提高了火电厂用煤效率. 相似文献
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在反应温度20℃、紫外光强度700～750μW/cm2、照射时间2h、电磁搅拌时间2h、溶液初始浓度20mg/L的实验条件下,TiO2-膨润土的投加量对光催化降解十二烷基苯磺酸钠(SDBS)的效果有影响:随着TiO2-膨润土投加量由0.01‰增加到0.5‰,SDBS的降解率逐渐提高,当投加量为0.5‰时,光催化降解率最高,达92％,以后随着投加量的增加(从0.5‰到6‰),降解效率反而下降.可见,最佳投加量为0.5‰.在相同实验条件下,投加0.17‰的TiO2(与0.5‰的TiO2 -膨润土中含Ti量相同),SDBS的降解率只有40％.可见,相比TiO2,TiO2-膨润土具有投加量小,降解效率高的优点,更实用. 相似文献