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一颗印泥石流沟位于四川省西北部理县境内,具有典型泥石流沟谷特征,历史上曾经暴发过大型泥石流."5·12"汶川地震在沟谷中形成了丰富的松散同体物源,同时导致沟谷流通区中出现多处堵塞,初步推测震后10～20a将处于泥石流活跃期.通过野外考察及遥感影像数据,获得地震前后沟谷的流域特征信息,对比分析地震前后沟谷内物源分布情况及稳定状况后,得出地震后沟谷内不稳定物源量增多,同时受震后堰塞影响,泥石流活动强度增大,泥石流峰值流量成倍增长等结论,这些将为合理评价地震后泥石流发展趋势,在灾后重建过程中为泥石流的预测、预报及防治工作提供参考. 相似文献
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"5.12"汶川地震除直接造成了严重的人员伤亡和财产损失外,还诱发了大量的崩塌、滑坡等次生山地灾害。崩塌、滑坡等又为震区泥石流活动提供了丰富的松散固体物质,使这些泥石流沟在今后较长一段时间内处于活跃期。以地震重灾区陇南柏水沟泥石流为例,在分析泥石流形成条件和泥石流特征的基础上,预测其发展趋势,并根据泥石流危险性提出了相应的防治建议。 相似文献
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汶川地震通过诱发滑坡和崩塌产生大量松散固体物质促进了泥石流的暴发,且大多数地震次生泥石流为超大规模,对地震灾后重建造成严重威胁。从区域上进行泥石流灾害危险性评估是目前地震灾区恢复重建和区域经济发展所必须而又紧迫的工作。通过对地震次生泥石流形成条件的分析,提出了一种基于泥石流物源数量,并结合遥感及GIS技术的泥石流危险性快速评估方法。通过在都江堰白沙河59个小流域的应用证明,评估结果与实际灾害情况较吻合,能够为地震灾区泥石流防灾减灾提供参考。此方法适用于地震灾区在短时间内物源突然富集的流域,并且受到遥感图像精度的影响,同时也具有一定时限性,需要根据遥感图像进行周期性更新。此方法能对地震灾区大区域泥石流危险性进行快速评估分级,尤其适用于野外调查无法开展的河流上游区域的泥石流评估。 相似文献
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炉城镇柳杨沟泥石流灾害及其形成条件探讨 总被引：1，自引：0，他引：1
康定县地处川西平原与四川盆周的过渡地带,县域内地势险峻,地形切割强烈,地层与地质构造复杂,新构造运动强烈,地震活动频繁,泥石流、滑坡、崩塌等地质灾害十分发育。作者通过收集资料与现场调查,分析研究了康定县城一典型泥石流——柳杨沟泥石流的活动概况、危害、形成条件及其形成机制,并对防治对策提出了建议。 相似文献
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从辽宁省东部山区泥石流暴发的特点看，暴雨只是泥石流产生的一个激发因素，泥石流活动区分布于地壳快速上升，地震活动频繁的地带，泥石流活动的高潮与该区地震激动期基本一致由于说明辽宁东部山区泥石流其孕育，发展和活动主要受内力地质作用所控制。 相似文献
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汶川地震后肖家沟泥石流活动特征与灾害防治 总被引：1，自引：0，他引：1
肖家沟是汶川地震震中映秀镇近邻的一条典型泥石流沟,位于渔子溪河左侧,沟域面积7.19 km2,沟床平均纵比降为485‰。"5·12"地震后该沟多次暴发泥石流。2010年8月14日,肖家沟暴发特大规模泥石流,一次冲出物方量约6.50×105 m,堵塞渔子溪,堰塞湖溃决后造成洪水灾害。肖家沟泥石流物源条件非常丰富,地区降水充沛,危险性巨大,一旦发生泥石流,直接威胁S303映秀段公路,造成交通中断;若发生大规模泥石流堵塞渔子溪形成堰塞体,堰塞体溃决之后,大量泥沙被洪水带至下游,抬高河床,将对下游映秀镇产生严重的洪水灾害。目前肖家沟沟域内共有松散固体物源量5.22×106 m3,可参与泥石流活动的动储量为2.01×106 m3。以肖家沟泥石流形成条件为基础,分析震后连续发生的泥石流类型与活动特征,并以此为依据探讨了肖家沟泥石流治理的简要思路。 相似文献
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5·12地震后灾区泥石流危险度增加系数评价 总被引：2，自引：0，他引：2
5.12地震不仅直接引发了大量的崩塌、滑坡,而且降低流域内岩土体的强度,使其更易于受到侵蚀,从而为泥石流的形成提供丰富的固体物质。灾区震后泥石流活动频繁,并造成了较大的损失。泥石流沟的危险度评价是进行灾后重建的必要条件。选择震后固体物质增加量、地震烈度和堰塞坝规模这3个重要参数,提出了基于泥石流设计流量的震后泥石流危险度增加系数的评价方法。该方法通过计算地震后新增加的固体物质方量与通过配方法计算出的一次泥石流冲出物总量的比值,该比值与地震烈度影响系数的乘积及堰塞体蓄水量以流域50年一遇的流量排泄所需要时间3项之和来表达地震后泥石流危险度增加量。经灾区9条典型泥石流沟谷的计算验证,该方法做为一种新的方法,可快速、准确地评价5.12地震后灾区泥石流危险度的增加情况。 相似文献
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风化作用对沟谷型泥石流发育环境的影响研究 总被引：1，自引：0，他引：1
地质条件是泥石流发育环境的三大条件之一,其主要作用是为泥石流提供固体物源。风化作用对产生泥石流固体物源的影响很大。以岩石的坚固系数为基础,研究了物理及化学风化对形成泥石流固体物源的影响。研究结果表明:(1)物理风化是形成泥石流物源的主要原因,冰劈作用往往造成强烈的物理风化,有利于泥石流的发育(2)化学风化不直接提供固体物源,但碳酸根离子的存在使化学风化不利于泥石流的发育。研究得出岩石坚固系数的物理风化和化学风化修正方法,最终得到形成泥石流的地质因子。形成泥石流的地质因子在汶川地震影响区内判别泥石流的暴发与否的应用研究中取得了较好的结果。 相似文献
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Cinnamon bark proanthocyanidins as reactive carbonyl scavengers to prevent the formation of advanced glycation endproducts 总被引：1，自引：0，他引：1
Peng X Cheng KW Ma J Chen B Ho CT Lo C Chen F Wang M 《Journal of agricultural and food chemistry》2008,56(6):1907-1911
Cinnamon bark has been reported to be effective in the alleviation of diabetes through its antioxidant and insulin-potentiating activities. In this study, the inhibitory effect of cinnamon bark on the formation of advanced glycation endproducts (AGEs) was investigated in a bovine serum albumin (BSA)-glucose model. Several phenolic compounds, such as catechin, epicatechin, and procyanidin B2, and phenol polymers were identified from the subfractions of aqueous cinnamon extract. These compounds showed significant inhibitory effects on the formation of AGEs. Their antiglycation activities were not only brought about by their antioxidant activities but also related to their trapping abilities of reactive carbonyl species such as methylglyoxal (MGO), an intermediate reactive carbonyl of AGE formation. Preliminary study on the reaction between MGO and procyanidin B2 revealed that MGO-procyanidin B2 adducts are primary products which are supposed to be stereoisomers. This is the first report that proanthocyanidins can effectively scavenge reactive carbonyl species and thus inhibit the formation of AGEs. As proanthocyanidins behave in a similar fashion as aminoguanidine (AG), the first AGE inhibitor explored in clinical trials, they show great potential to be developed as agents to alleviate diabetic complications. 相似文献
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低磷胁迫下熊猫豆侧根增多的生理机制研究 总被引：3，自引：2，他引：1
采用溶液培养方法,通过外源添加生长素吲哚-3-乙酸（IAA）及生长素极性运输抑制剂2,3,5-三碘苯甲酸（TIBA）,研究了低磷胁迫下熊猫豆根系构型与生长素相关代谢酶活性之间的关系,以阐明生长素在低磷胁迫下塑造植物根系构型的作用。结果表明,熊猫豆在低磷胁迫下形成特定根系构型,具体表现为侧根增多。IAA在侧根发生过程中起重要作用,外源IAA可以在一定程度上模拟低磷信号引导的侧根发生,而生长素极性运输抑制剂TIBA则显著抑制侧根发生。根系中生长素代谢相关酶生长素氧化酶（IAAO）和过氧化物酶（POD）活性在根构型形成过程中呈现规律性变化。低磷环境下熊猫豆根系中的IAAO、 POD酶活性均高于正常施磷的处理。外源IAA可以增加这两种酶的活性,而TIBA则能够逆转低磷诱导的IAAO、 POD活性的增加。 相似文献
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本文首次对我国原始土壤的酶活性及其与土壤肥力因素的相关性作了初步研究。结果表明:随着岩生地衣向苔藓、草甸的演替。过氧化氢酶。转化酶、脲酶、蛋白酶、磷酸酶活性逐渐降低,多酚氧化酶活性逐渐升高;转化酶、蛋白酶、磷酸酶和脲酶活性与有机质非常显著相关(10.0相似文献
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Traute-Heidi Anderson 《植物养料与土壤学杂志》1991,154(6):409-416
Significance of microorganisms in aggregate formation In soils microorganisms are the biological link between the physicochemical processes of synthesis and degradation. Because of their metabolic activities and their mechanical binding capacities they are directly involved in the development of soil structure. This review attempts to summarize knowledge of experimental work concerning aggregate formation by microorganisms. Especially distribution, adhesion processes, significance of biopolymers in aggregate formation and destabilization will be covered. The current state of art and open research areas will be indicated. 相似文献
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Phosphatidylethanolamine (PE), phosphatidylcholine (PC), lysine (Lys), and mixtures of them were tested for antioxidative activity in refined olive oil by the Rancimat method to investigate the role of the chemical reactions produced in the Rancimat vessel on the induction periods (IPs) obtained. PE and Lys, but not PC, increased the IPs of the oil when tested alone. In addition, PE/Lys and PC/Lys mixtures, but not PC/PE mixtures, exhibited a synergistic effect. All these results can be understood considering the in situ formation of oxidized lipid/amino compound reaction products with antioxidative activities. Thus, the formation of pyrroles could be detected after derivatization with p-(dimethylamino)benzaldehyde, and some of these compounds could be unambiguously identified by GC-MS after their conversion into volatile derivatives. In addition, the formed products contributed to the color developed, and a correlation was observed between the Rancimat IPs obtained and the yellowness index of the oxidized oils recovered from the Rancimat. Furthermore, the differences observed in the antioxidative activities of PE, PC, Lys, and their mixtures could be explained according to the lipophility and hydrophility of the oxidized lipid/amino compound reaction products formed. All these results suggest that chemical reactions are being produced in the Rancimat vessel and the Rancimat IPs obtained are a consequence of the antioxidative activities of the products formed in these reactions. Furthermore, Rancimat may be a valuable tool for testing antioxidative activities of antioxidants produced during food processing if favorable conditions for antioxidant formation are employed. 相似文献
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Lee KG Shibamoto T Takeoka GR Lee SE Kim JH Park BS 《Journal of agricultural and food chemistry》2003,51(24):7203-7207
The antioxidant activities of naturally occurring plant compounds were measured in a lipid peroxidation system consisting of ethyl arachidonate and Fenton's reagent. Inhibitory effects of 24 plant-derived flavonoids and 5 phenolic acids on malonaldehyde (MA) formation from ethyl arachidonate were examined using gas chromatography (GC) with a nitrogen-phosphorus detector (NPD). Luteolin, which showed the strongest antioxidant activity, inhibited MA formation by 94% and 97% at the levels of 0.5 and 1.0 mM, respectively. The antioxidant activities of the flavones and flavonols decreased in the following order: luteolin > rhamnetin > fisetin > kaempferol > morin > quercetin. Among the flavanones tested, hesperitin, taxifolin, and naringenin exhibited appreciable antioxidant activities (61-84%) at the 1.0 mM level. The inhibitory effect of epigallocatechin gallate (82.5% at the 1.0 mM level) was the strongest among the flavan-3-ols tested. Ferulic acid had the most potent antioxidant activity (74.6% at the 1.0 mM level) of the phenolic acids tested. 相似文献
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Eurasian Soil Science - In the course of field and laboratory studies, the activities of nitrogen fixation, denitrification, CO2 emission, and methane formation in an oligotrophic peat soil were... 相似文献
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关中塿土发生特性与分类研究进展 总被引：1，自引：0，他引：1
塿土是关中地区受人类活动影响深刻的重要农业土壤,而对其发生分类及系统分类的归属仍有较大争议。本文综述了塿土的形成过程和成土过程特点,塿土发生分类归属的变更,系统分类的主要诊断层、诊断特性和诊断现象,高级分类单元归属及空间分布,基层分类单元的主要诊断指标等方面的研究进展。在此基础上,展望了塿土需要进一步开展的研究工作包括3个方面:①深入理解人为影响下塿土的成土过程,定量化分析覆盖层的形成过程;②开展塿土覆盖层厚度调查,界定堆垫表层的厚度标准;③进行土壤普查,建立塿土代表土系。 相似文献
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Aroma extracts from fresh soybeans, mung beans, kidney beans, and azuki beans were prepared using simultaneous steam distillation and solvent extraction (SDE) under mild conditions (55 degrees C and 95 mmHg). Extracts were examined for antioxidative activities in two different assays. The aroma extracts isolated from all beans inhibited the oxidation of hexanal for nearly one month at a level of 250 microL/mL. Mung bean and soybean extracts inhibited malonaldehyde (MA) formation from cod-liver oil by 86% and 88%, respectively, at the 250 microL/mL level. Azuki and kidney bean extracts inhibited MA formation from cod-liver oil by 76% and 53%, respectively, at the 250 microL/mL level. The antioxidative activities of mung bean and soybean extracts were comparable with that of the natural antioxidant, alpha-tocopherol (vitamin E). 相似文献
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以春石斛兰(Dendrobium nobileSw.)为试材,研究了类原球茎在分化芽和根系发生过程中抗氧化酶系统中多种酶活性及可溶性蛋白的变化规律。结果表明,在分化过程中抗坏血酸过氧化物酶(APX)、愈创木酚过氧化物酶(POD)、多酚氧化酶(PPO)和过氧化氢酶(CAT)的活性和可溶性蛋白含量均呈现先降后升的趋势;超氧化物歧化酶(SOD)活性则呈现先升后降的变化。对过氧化物酶同工酶和可溶性蛋白进行SDS-PAGE电泳发现,在分化过程中均有新谱带的产生或原有谱带的消失。 相似文献