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941.
采用稀燃-富燃交替运行方式,研究存储-还原型催化剂Pt/MgO的NOx存储性能以及C3H6还原NOx反应性能.氧化存储段,NOx可被有效存储;当氧化性气氛转换为还原性气氛后,出现一个NOx峰,降低了总的转化效果.NOx峰的大小与存储段和还原段时间之比、温度等因素有关;400℃时NOx峰最小,总转化率最高.5 h循环实验表明,400℃时Pt/MgO催化剂再生良好,NOx转化率稳定在96%.于反应气氛中添加100 mg/m3SO2进行了5 h抗硫性实验,Pt/MgO催化剂的抗硫中毒能力明显强于Pt/BaO/Al2O3. 相似文献
942.
湘早优1号苦瓜杂交制种高产栽培技术 总被引:1,自引:0,他引:1
由于湘早优1号苦瓜大面积在推广过程中遇到了实际问题,通过对杂交种子生产过程中的播种期、种植密度、植株药物处理等研究,采用侧枝进行二次制种的方法,提高了种子产量,降低了制种成本,总结了二次制种高产栽培技术.参4. 相似文献
943.
Xian Q Chen H Liu H Zou H Yin D 《Environmental science and pollution research international》2006,13(4):233-237
Background, Aims and Scope
Vallisneria spiralis Linn., a common, submerged macrophyte, is widely available in quiet waters of lakes, ponds, marshes and streams in Southeast Asia. V. spiralis plays a significant role not only in decreasing eutrophication of water body for its productivity, but also in inhibiting the growth of blue-green algae? The aim of the paper involves the isolation and identification of allelochemicals from extracts of V. spiralis by activity-guided fractionation and column chromatography.Methods
Leaves of V. spiralis was washed free of debris, air-dried and refluxed in 95% EtOH. The extract was isolated using column chromatography and fractionation with antialgal activity. Potential allelochemicals were analyzed by high-resolution gas chromatography-mass spectrometry (HRGC-MS).Results
Two fractions with strong antialgal activity were isolated using column chromatography and activity-guided fractionation from the extract of V. spiralis. 2-Ethyl-3-methylmaleimide, dihydroactinidiolide and 4-oxo-β-Ionone were identified in the first fraction, and 3-hydroxy-5,6-epoxy-β-ionone, loliolide, 6-hydroxy-3-oxo-α-ionone and an unknown compound in the second fraction. They had strong inhibitory effects on Microcystis aeruginosa Kütz.Discussion
2-Ethyl-3-methylmaleimide is a byproduct of photooxidation of chlorophyll, and five other compounds identified were derivatives of β-carotene. HRGC-MS and derivatization technology were used to identify and confirm their molecular structures. The formula of the unknown compound was C16H19NO4. Metabolites of plant pigments had strong inhibitory activities on growth of algae.Conclusions
Six compounds had been identified in V. spiralis, among them, 2-ethyl-3-methylmaleimide was the main allelochemical, and derivatives of ionone were also potential allelochemicals.Recommendations and Perspective
. The results of our research could help us to study further mechanisms of inhibitory effect on algae and develop new potential antialgal substances. 相似文献944.
分析了不同污染负荷下膜生物反应器的运行效率,并运用酶活表征污泥活性,用磷脂脂肪酸(PLFAs)分析微生物种群结构及其分布特征.结果表明,膜生物反应器对COD,TP,TN,NH4+-N 保持着高而稳定的去除率,不同有机负荷下去除率差异不大(P>0.05);磷酸酶活性在低污染负荷下最高,脱氢酶、β-糖苷酶在中低污染负荷时的活性比高污染负荷时高,脲酶及蛋白酶活性随负荷增加而升高;活性污泥PLFAs 组成以单不饱和脂肪酸、饱和脂肪酸和支链脂肪酸为主,而多不饱和脂肪酸与环丙烷脂肪酸含量较少,特征脂肪酸的比值表明在反应器中好氧细菌占绝对优势;微生物的群落结构分析显示,活性污泥中好氧原核微生物为优势类群,其次是革兰氏阳性细菌及其他厌氧细菌,而真核微生物所占比例最低. 相似文献
945.
Chao Tai Shaodong Zhang Jing Wang Yongguang Yin Jianbo Shi Haoxian Wu Yuxiang Mao 《Environmental Chemistry Letters》2017,15(3):515-523
Singlet oxygen (1O2) and hydroxyl radical (·OH) play an important role in the degradation of pollutants in surface waters. However, the mechanism underlying the photochemical generation of 1O2 and ·OH in wastewaters is poorly known. Here we studied the photo-induced generation of 1O2 and ·OH in different sewage treatment plant units. The correlation between the generation of 1O2 and ·OH and the water constituents was discussed. Our results show that in sewage units the 1O2 formation rate ranges from 2.19 × 10?8 to 6.74 × 10?8 mol L?1 s?1, and the ·OH formation rate ranges from 1.7 × 10?11 to 3.06 × 10?10 mol L?1 s?1. The average 1O2 formation rates in the various sewage units are similar to those in wetland and estuarine waters containing rich dissolved organic matter and 2–4 times higher than those in lake and seawater samples. The average ·OH formation rates of the sewage units are 5–50 times higher than for other water samples reported. The ·OH generation rate increased with the iron content with a correlation coefficient of 0.85, which indicates that the photo-Fenton reaction plays a dominant role in ·OH generation in sewage wastewater. 相似文献
946.
环境保护部令第2号《建设项目环境影响评价管理名录》(以下简称《名录》)自2008年10月1日施行,各级环保部门据此对建设项目的环境影响评价实行分类管理。本文结合工作实际,浅析如何准确灵活把握《名录》,促进社会经济和谐发展。 相似文献
947.
Huan Zhong Ping Li Yongguang Yin Pei Lei Nan Zou Yujiao Liu Weiping Cai Mengjie Wu Wenli Tang Yong Cai Xinbin Feng Shuxiao Wang 《环境科学学报(英文版)》2022,119(9):78-92
Mercury (Hg) could be microbially methylated to the bioaccumulative neurotoxin methylmercury (MeHg), raising health concerns. Understanding the methylation of various Hg species is thus critical in predicting the MeHg risk. Among the known Hg species, mercury sulfide (HgS) is the largest Hg reservoir in the lithosphere and has long been considered to be highly inert. However, with advances in the analytical methods of nanoparticles, HgS nanoparticles (HgS NPs) have recently been detected in various environmental matrices or organisms. Furthermore, pioneering laboratory studies have reported the high bioavailability of HgS NPs. The formation, presence, and transformation (e.g., methylation) of HgS NPs are intricately related to several environmental factors, especially dissolved organic matter (DOM). The complexity of the behavior of HgS NPs and the heterogeneity of DOM prevent us from comprehensively understanding and predicting the risk of HgS NPs. To reveal the role of HgS NPs in Hg biogeochemical cycling, research needs should focus on the following aspects: the formation pathways, the presence, and the environmental behaviors of HgS NPs impacted by the dominant influential factor of DOM. We thus summarized the latest progress in these aspects and proposed future research priorities, e.g., developing the detection techniques of HgS NPs and probing HgS NPs in various matrices, further exploring the interactions between DOM and HgS NPs. Besides, as most of the previous studies were conducted in laboratories, our current knowledge should be further refreshed through field observations, which would help to gain better insights into predicting the Hg risks in natural environment. 相似文献
948.
公路沿线弃渣场的失稳破坏,不仅容易造成其下方道路和河流的堵塞,而且严重威胁人民的生命和财产安全.快速、准确和批量地评价公路沿线弃渣场危险性就显得十分必要.通过对公路沿线弃渣场进行遥感图像识别、无人机拍摄、现场调查及试验,确定了6个弃渣场危险性影响因子,运用物质点法对实体弃渣场进行了多因素多水平的数值模拟,得出各因子对弃... 相似文献
949.
本文详细分析了高职院校学生中非正式群体产生的心理原因、类型、特征和功能,提出了切实可行的教育对策. 相似文献
950.