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201.
本文针对天津台网所有台站,抽取一天24个小时的波形资料,通过计算得到各台站的噪声水平。在台网监测能力计算中加入相应噪声水平,从而得到噪声影响下的台网的监测能力为天津市区ml1.0,东部沿海监测能力为ml2.0,北部山区监测能力为ml2.3。即是台网的实际运行、工作中的监测能力。 相似文献
202.
为了研究含铬浸出渣的调质解毒机理,建立了CaO-MgO-FeO-Na2O-SiO2-Al2O3-Cr2O3七元渣系活度模型,基于共存理论的活度模型得出了铬渣中主要组分及复合氧化物在不同条件下的活度。所得的结果表明,铬渣中Cr2O3主要形成了Na2Cr2O4和CaCr2O4,这两种复合氧化物不稳定,在自然环境中分别会被氧化为水溶性的铬酸钠(Na2CrO4)和酸溶性的铬酸钙(CaCrO4),释放出具有强毒性的Cr(Ⅵ),是造成铬污染的主要原因。温度、碱度以及渣中FeO含量都能影响渣系组分的活度。在1700K下,将铬渣碱度调至1.14,并加入30%的FeO能够使Cr2O3的有效固定率提高至88.2%,基本实现了铬渣的解毒。 相似文献
203.
The decay of wood and other cellulosic materials by fungi cause significant economic loss. The widely used chromated copper arsenate was prohibited for the environmental impact and safety of arsenic and chromium. It was found that natural product hinokitiol (HK) had fungicidal and insecticidal activities, and its toxicity was bearable for the environment. We described the practical synthesis of HK-K salt. According to the GB/T18261-2000 and LY/T1283-1998, wood preservative performance of HK-K salt was tested. The results showed that the best inhibitory concentration of HK-K salt was 50 mg/L, for which the prevention effectiveness on mold is better, the killed value is between 0 and 1, and the corrosion-resistant for wood-rotting fungi is grade A. 相似文献
204.
汽车尾气对空气的污染越来越严重,影响人们的健康生活,破坏生态环境。机动车尾气中的氮氧化物是大气污染的主要污染物之一,采取有效措施减少机动车氮氧化物排放对于空气质量的改善具有重要意义。 相似文献
205.
Green leaf volatiles (GLVs) emitted by plants after stress or damage induction are a major part of biogenic volatile organic compounds (BVOCs). Proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS) is a high-resolution and sensitive technique for in situ GLV analyses, while its performance is dramatically influenced by humidity, electric field, etc. In this study the influence of gas humidity and the effect of reduced field (E/N) were examined in addition to measuring calibration curves for the GLVs. Calibration curves measured for seven of the GLVs in dry air were linear, with sensitivities ranging from 5 to 10 ncps/ppbv (normalized counts per second/parts per billion by volume). The sensitivities for most GLV analyses were found to increase by between 20% and 35% when the humidity of the sample gas was raised from 0% to 70% relative humidity (RH) at 21°C, with the exception of (E)-2-hexenol. Product ion branching ratios were also affected by humidity, with the relative abundance of the protonated molecular ions and higher mass fragment ions increasing with humidity. The effect of reduced field (E/N) on the fragmentation of GLVs was examined in the drift tube of the PTR-TOF-MS. The structurally similar GLVs are acutely susceptible to fragmentation following ionization and the fragmentation patterns are highly dependent on E/N. Overall the measured fragmentation patterns contain sufficient information to permit at least partial separation and identification of the isomeric GLVs by looking at differences in their fragmentation patterns at high and low E/N. 相似文献
206.
我国人口问题与可持续发展 总被引:6,自引:0,他引:6
庞丽华 《中国人口.资源与环境》1997,7(3):71-75
人口因素在“人口、资源、环境、经济、社会”可持续发展系统中处于中心地位。本文从可持续发展角度,探讨了我国人口数量、质量、结构、分布等方面存在的问题,并对其优化方向作了简要分析。 相似文献
207.
HaiRong Zhang Hao Pang Lei Zhang Xinde Chen Bing Liao 《Journal of Polymers and the Environment》2013,21(2):329-334
Polyurethane foam (PUF) was prepared from liquefied wood with polymethylene polyphenylisocyanate by one-shot method, with organosilicon as surfactant, water as blowing agent and stannous octoate and triethylene diamine as co-catalyst. The biodegradability of the PUF was studied by soil burial for a period of 12 months. The Fourier transform infrared (FT-IR) study, morphological observation and percent weight loss were used to discuss the biodegradability of polyurethane foam from liquefied wood. The FT-IR analyses showed that the PUF had biodegraded via oxidation of the ether soft segment or degradation of wood components. The weight loss rate showed that the addition of liquefied wood could accelerate the degradation of PUF. 相似文献
208.
209.
Alex H.S. Chik Melissa B. Glier Mark Servos Chand S. Mangat Xiao-Li Pang Yuanyuan Qiu Patrick M. DAoust Jean-Baptiste Burnet Robert Delatoll Sarah Dorner Qiudi Geng John P. Giesy Robert Mike McKay Michael R. Mulvey Natalie Prystajecky Nivetha Srikanthan Yuwei Xie Bernadette Conant Steve E. Hrudey 《环境科学学报(英文版)》2021,33(9):218-229
210.
利用盆栽试验研究Cu、Ni、As、Cr4个元素不同浓度对萝卜出苗的影响.结果表明,土壤含Cu50mg/kg以上时,随着含Cu量的增加,出苗数随之减少.在酸性土壤上发生Cu和Ni危害时,可用提高土壤pH至中性的办法来消除.在中性土壤上,含Ni50mg/kg以上对萝卜出苗有害.Cu、Ni复合污染比单一元素污染的危害大,且毒性Ni>Cu.土壤Cr、As含量越大,对萝卜出苗的危害也越大,并且毒性Cr(6+)>Cr(3+). 相似文献