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1.
Studies on susceptibility to debris flows at regional scale(100-1000 km~2) are important for the protection and management of mountain areas. To reach this objective, routing models, mainly based on land topography, can be used to predict susceptible areas rapidly while necessitating few input data. In this research, Flow-R model is implemented to create the susceptibility map for the debris flow of the Vizze Valley(BZ, North-Eastern Italy; 134 km~2). The analysis considers the model application at local scale for three sub-catchments and then it explores the model upscaling at the regional scale by verifying two methods to generate the source areas of debris-flow initiation. Using data of an extreme event occurred in the Vizze Valley(4 August 2012) and historical information, the modeling verification highlights that the propagation parameters are relatively simple to set in order to obtain correct runout distances. A double DTM filtering-using a threshold for the upslope contributing area(0.1 km~2) and a threshold for the terrain-slope angle(15°)-provides a satisfactory prediction of source areas and susceptibility map within the geological conditions of the Vizze Valley.  相似文献   

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A new damage-locating method for bridges subjected to a moving load is presented, and a new ‘moving load damage-locating indicator' (MLDI) is introduced. A vehicle is modeled as a moving load, the bridge is simplified as an Euler-Bernoulli beam, and the damage is simulated by a reduction of stiffness properties of the elements. The curvature and MLDI values at each node of the baseline model (undamaged) and the damage model are computed respectively. Then the damage or damages can be located from a sudden change of the MLDI value. The feasibility and effectiveness of the proposed method are validated by numerical simulation. The results indicate that the method is effective, being able to not only locate a single damage accurately, but also locate multiple damages in simply-supported bridges, including multiple damages in continuous bridges. The results also indicate that the MLDI can accurately locate damages under 5% measurement noise.  相似文献   

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A diatom was purified with colony selection and continuous dilution methods. It was identified to Cylindrotheca closterium according to its morphological characteristics and rbc L and 18 s r RNA gene sequences. The alga was not sensitive to ampicillin and neomycin, but sensitive to chloramphenicol which inhibited its growth at concentrations ranging from 50 to 150 μg m L-1. The purified alga was easy to culture and its specific growth rate was 0.207 ± 0.002(d-1). It was resistant to pollution and could be harvested in an easy way. It was relatively high in lipid content(20.08% ± 0.67% of dry weight) and the combined amount of its 16:0 and 16:1(n-7), the most suitable resource of biodiesel, was as high as 64% of the total fatty acids, while the amount of polyunsaturated fatty acids reached 19.96%–20% of the total fatty acids. Thus the purified C. closterium can be cultured as a biodiesel producer or a nutrition supplement producer.  相似文献   

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Reducing the threats of sulfate ion(SO_4~(2-))deposition to terrestrial ecosystems is a great challenge.The canopy interception effect on SO_4~(2-)deposition has been well documented,but the interception efficiency of the gap edge remains unknown.Therefore,a subalpine dragon spruce(Picea asperata) plantation was evaluated in the upper reaches of the Yangtze River.The dynamics of the SO_4~(2-) concentration in the throughfall were investigated from the gap edge to the closed canopy during the rainfall and snowfall periods from August 2015 to July 2016.The annual input of SO_4~(2-) totaled 2.56 kg/ha through rainfall and 0.69 kg/ha through snowfall.The total annual net interception fluxes(NIFs) of SO_4~(2-) at the gap edge and in the closed canopy were 1.48 kg/ha and 0.66 kg/ha,respectively,and the net interception ratios(NIRs) accounted for 45.40% and 20.25%,respectively.The NIF and the NIR of SO_4~(2-) at the gap edge were higher than those in the closed canopy.Therefore,the results suggested that a significant amount of SO_4~(2-) deposition was intercepted by the tree canopy in the subalpine plantation,with more SO_4~(2-) deposition at the gap edge than in the closed canopy,which is beneficial for improving the water quality in the upper reaches of the Yangtze River via forest management.  相似文献   

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泰安市人地矛盾比较突出 ,人均土地 0 .14公顷 ,人均耕地只有 0 .0 6公顷 ,均低于全国、全省平均水平。随着经济社会的发展和城市化进程的加快 ,土地的供求矛盾更加尖锐。为优化配置土地资源 ,盘活土地资产 ,完善和规范土地市场 ,更好地发挥土地资产在经济发展中的作用 ,建立适应社会主义市场经济体制需要的土地使用制度 ,去年以来 ,泰安市以国家法律法规为依据 ,积极借鉴外地成功经验 ,立足实际 ,开拓创新 ,大力推进以有偿使用为重点的土地使用制度改革 ,取得了良好的效果。1 大胆实践 ,全面推进土地使用制度改革1.1 认清形势 ,充分认识…  相似文献   

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砖瓦窑厂属于用落后的工艺生产落后的产品的建材行业。不仅耗能高、资源利用价值低.而且严重污染环境。因此,国家对投资砖瓦窑厂有严格的限制条件。限制开办砖瓦窑厂在《土地管理法》,《矿产资源法》、《基本农田保护条例》等国家法律中有明确规定,同时.在有关  相似文献   

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The Manila clam Venerupis philippinarum is a good biomonitor/bioindicator to marine metal pollution and is frequently used in aquatic toxicology. Two dominant pedigrees (white and zebra) of clam are distributed in the Bohai Sea; however, little attention has been paid to potential biological differences between these two pedigrees. In this study, we tested the sensitivity of both pedigrees to marine metal (cadmium and zinc) pollution biomonitoring and marine environmental toxicology. Results demonstrate significant biological differences in gills of white and zebra clams based on metabolic profiles and antioxidant enzyme activities. In addition, we found that hypotaurine, malonate and homarine were relatively high in white clam gills, while alanine, arginine, glutamate, succinate, 4-aminobutyrate, taurine and betaine were high in zebra clam gills. Zebra clam gills were also more sensitive to a mixture of Cd and Zn, as shown by antioxidant enzyme activities and metabolic profiles, but white clam gills could accumulate more Zn. Therefore, we suggest that the white pedigree can be used as a biomonitor to marine Zn pollution, whereas the zebra pedigree can be used for toxicology studies on Cd and Zn mixed pollution.  相似文献   

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He-shen  Hou  Ning  Li  Chao-yuan  Wu 《中国海洋湖沼学报》1998,16(1):25-29

During the induction of gamete-producing gametangia, induced gametophytes were collected at 4 days intervals (0,4,8,12 d) and total RNAs were isolated by CsCl gradient ultracentrifugation. Some stage-specific expressed mRNAs were identified by differential display of mRNAs from different developing stages of the gametophytes. The cDNA of one specific mRNA was verified, cloned and sequenced. This gene was specifically expressed during 4 days of induction, and had partial homologous sequence with tobacco IAA-binding protein gene. It suggests that this cDNA may represent a gene which is related to the IAA regulating function during the development of the gametophytes.

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10.
介绍了WTO成员国土地(不动产)税收体系的构成类型.对中国土地税收格局及存在问题作了阐述;提出了构建与WTO成员国接轨的中国土地税收格局的改良办法.  相似文献   

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设F为区域D内的亚纯函数族n(≥3),m(≥1)为两正整数,6为非零有穷复数,若对 f,g∈F,在D内f"(f"-1)f'与g"(g"'-1)g'IM分担b.则F在D内正规.  相似文献   

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节能降耗,任重道远——漫长的循环经济之路   总被引:1,自引:0,他引:1  
"十五"期间,我国国民经济保持高速增长,但是,高能耗、高物耗、污染重的粗放经济增长方式没有得到根本转变。在工业领域,能源消费超常规增长,能源结构仍然以煤炭为主,能源消耗量大,污染物排放量大。而生态农业建设虽然部分地缓解了农村经济发展与环境保护之间的矛盾,但其只是在低层次上实现了物质能量的循环,废弃物利用率较低,有机农业发展缓慢。如果继续沿袭传统的以资源的大量消耗为代价实现工农业现代化的发展模式,是难以持续的。为了减轻经济增长对资源供给的压力,必须大力发展循环经济,实现资源的高效利用和循环利用。本文从六个方面分析了目前我国发展循环经济的主要措施、存在的问题及解决的途径:加强对太阳能的利用,重视多晶硅规模生产技术的自主研发;发展风力发电,培育风电设备制造产业;利用秸秆发电,发展可部分替代传统化石能源的生物质能源;推动以节能、节地、节水、节材和环保为核心的绿色建筑技术发展;节水与集雨;加强土壤污染监测与防治,通过人工方法修复天然的生态系统。通过分析,作者认为,发展循环经济是缓解资源约束矛盾、节能降耗的根本出路,在我国任重而道远。  相似文献   

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By applying experimental and numerical simulations, the motion performance of a semi-submersible platform with mooring positoning system under combined actions of wind and waves is studied. The numerical simulation is conducted by the method of nonlinear time domain coupled analysis, and the mooring forces are calculated by the piecewise extrapolating method. The scale in the model experiment is 1:100, and the mooring system of the model is designed with the method of equivalent water-depth truncation by comparing the numerical and the experimental results, the platform motion and mooring forces subject to wind and waves are investigated. The results indicate that the numerically simulated mooring forces agree well with the experimental results in static equivalent field, but show some difference in dynamic equivalent field; the numerically simulated platform motions coincide well with the experimental results. The maximum motion of the platform under operating conditions is 20.5 m. It means that the horizontal displacement is 2% less than the water depth, which satisfies the operating requirements.  相似文献   

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Based on the Navier-Stokes Equations (NSE), numerical simulation with fine grids is conducted to simulate the coastal surface wave changes, including wave generation, propagation, transformation and interactions between waves and structures. This numerical model has been tested for the generation of the desired incident waves, including both regular and random waves. Some numerical results of this model are compared with available experimental data. In order to apply this model to actual cases, boundary conditions are considered in detail for different shoreline types (beach or breakwater, slope or vertical wall, etc. ). Finally, the utility of the model to a real coastal area is shown by applying it to a fishing port located in Shidao, Rongcheng, Shandong Province, P.R. China.  相似文献   

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阐述了汤山金矿的发现过程及其成因,汤山金矿采用“堆浸法”提取金,详尽描述了该方法提取金的工艺流程;破碎→制粒→筑堆→喷淋→吸附,并建议将汤山金矿作为旅游地学景点加以开发。  相似文献   

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教改是提高大学生就业率的关键环节   总被引:1,自引:0,他引:1  
从当前我国人力资源市场上大学生就业难的现象切入,通过分析大学生就业市场供求双方的经济关系,说明求职大学生在素质上与用人单位的需求之间存在较尖锐的矛盾,是大学生就业难的重要原因。解决大学生就业难的关键环节之一是通过教改提高大学生的综合素质。  相似文献   

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介绍了一种在PLD(可编程逻辑器件)设计中引入原本用在模拟电子系统中反馈的概念,利用输出信号来控制输入信号,从而得到最小的系统时延的反馈算法,使器件性能得到最大优化.  相似文献   

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鱼类诺卡氏菌病是全球性的鱼病,杀鲑诺卡氏菌(Nocardia salmonicida)是引起鱼类诺卡氏菌病的主要病原之一。根据杀鲑诺卡氏菌16S-23S转录间隔区(ITS)序列设计引物,建立特异性PCR检测杀鲑诺卡氏菌的方法。结果表明,筛选的PCR引物可特异性地扩增出杀鲑诺卡氏菌的ITS片段,检测灵敏度(DNA浓度)为28.3 pg·μL-1。检测人工感染杀鲑诺卡氏菌的鱼组织,结果显示,该方法可从未分离到病原菌的病鱼组织中检出阳性片段,较传统细菌分离鉴定方法更为高效灵敏。  相似文献   

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