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421.
近年来城市暴雨频发导致内涝灾害广受关注,系统分析城市内涝原因是当前城市水文研究的热点和难点。论文以北京市典型积水点上清桥易积水区为例,基于排水管网、地形、下垫面、河道边界等数据构建研究区精细化洪涝模型,并以2012年“7·21”和2016年“7·20”两场典型暴雨的实测积水深度验证模型的适用性。结果表明,上清桥区域管网现状排水能力小于1 a一遇,当发生1 a一遇及以上设计降雨时上清桥有发生积水的风险。引起研究区积水频发主要有四方面因素,按主次关系排列:局部地势因素>管网因素>下垫面因素>河道顶托,最后基于分析结果系统提出解决上清桥区域积水的改造方案。  相似文献   
422.
利用水文水化学自动监测仪,于2018年5月18日至2018年12月3日期间对地处湿润亚热带季风气候条件下的贵州省施秉世界自然遗产地境内的黄洲河白云岩小流域进行了高时间分辨率的连续监测,目的是为了揭示湿润亚热带季风气候区典型白云岩小流域不同时间尺度与不同降雨强度下水文水化学动态特征。研究获得了黄洲河白云岩小流域的降雨量、出口流量、水温、电导率、pH、方解石及白云石饱和指数、CO_2分压等连续数据。结果表明:(1)黄洲河流域出口河水的pH、电导率、CO_2分压、方解石及白云石饱和指数等指标具有明显的日周期变化规律,即水温、pH、方解石及白云石饱和指数与气温的昼夜周期变化曲线相似,而电导率、CO_2分压与气温的日周期变化曲线相反;(2)黄洲河流域出口河水的水化学指标对不同强度的降雨会产生不同变幅与变化方向的响应特征,暴雨会显著干扰河水水化学指标的日周期变化规律,主要表现在随着降雨强度的增大,电导率与CO_2分压呈现显著下降;(3)白云岩流域具有明显的化学稳态行为。  相似文献   
423.
Otolith increment age estimates for a deepwater species, Allocyttus verrucosus, were validated by comparison with the results from 210Pb:226Ra radiometric analysis. Transverse sectioning and subsequent grinding of otoliths to a thickness of 0.2 mm revealed increments which provided age estimates for a range of fish sizes. Age estimates ranged from 7 yr for an immature fish of 15.2 cm total length (TL) to 130 yr for a female fish of 36.5 cm TL. Age at maturity was estimated as 28 yr for females and 24 yr for males. In comparison, radiometric analysis of whole otoliths, using a single linear otolith-mass growth-rate model suggested maximum ages of 130 to 170 yr for fish of 34 to 35 cm TL. Radiometric ages were also recalculated using a two-phase otolith-mass growth-rate model in which the growth rate was assumed to slow after maturity to 90% of the pre-maturity rate. This reduced the maximum age to 132±15 yr for a mean fish length of 34.5 cm. Age at maturity for females was estimated at 34 yr. The similarity between age estimates from otolith-increment counts and radiometric analysis strongly supports the accuracy of results from both methods, and encourages further use of such comparisons as an alternative to traditional validation techniques.  相似文献   
424.
425.
家用电器工频电磁辐射水平分析   总被引:2,自引:0,他引:2  
对电磁波的产生机理以及对人体的危害进行了分析阐述,对人们日常生活中的家用电器电磁辐射水平进行了调查测量,分析了不同家用电器的电磁辐射水平,并有针对性提出了一些科学有效的防护措施。  相似文献   
426.
Ranunculus spp. are the dominant plants of lowland chalk stream habitats in England. The spatial variability of sediment characteristics (silt–clay, organic matter, total phosphorus and total nitrogen content) within stands of Ranunculus spp. was investigated in 12 rivers in lowland England. Variability was found to be high and there were no discernible differences between samples taken from within Ranunculus and a limited number of samples from bare substrate. For two of these rivers, comparisons were also made between reaches upstream and downstream of waste water treatment works outfalls in terms of the characteristics of the sediments within Ranunculus stands. In one river a clear increase in sediment nutrient, fine and organic material content was observed downstream but in the other there was no consistent difference. Temporal variability was considered for two rivers in the Frome catchment, Dorset, by analysing the monthly variability in sediment organic matter and silt–clay content beneath Ranunculus stands over an annual cycle of growth and die-back. Whilst a clear pattern of fine and organic material retention consistent with seasonal plant growth patterns was evident at one site, the three sites displayed different temporal patterns. This inconsistency is believed to reflect differences in sediment supply at the three sites.  相似文献   
427.
Book reviews     
“Water Planning and the Regions”

Edited by P. J. Purdy, R. S. A.

Discussion Paper No. 9, 1977, £1.50.

Tenant participation in council housing management; Housing Development.

Directorate Occasional Paper 2/77, DoE London, 1977.

Getting tenants involved: a handbook on systems of tenant participation in housing management; DoE London, 1977.

La politica dei servizi tra razionalizzazione e rinnovamento

Alberto L'Abate (1978)

Marsilio Editori, Padova, pp. 316

Handbook for Environmental Planning: the social consequences of environmental change.

J. McEnvoy & T. Dietz (1977)

New York, J. Wiley, pp. 323. Price £15.50

Planning and Urbanism in China

Progress in Planning Vol. 8, Part 2, Fo. 1 N. Jeffrey and M. Caldwell, pp. 97–182, 1977

Pergamen, £4.00

The European Community's Regional Fund

Ross B. Talbot

Progress in Planning, Vol. 8, Part 3, pp. 183–281

Pergamon Press, 1977

Providing the Posh Words

W. Hampton, DoE

1978. £1.50. 60pp.

Four Titles on Conservation

A Critical Bibliography of Building Conservation. John F. Smith. Mansell, London 1978. 207 pages including index. Hard back, £12.90.

Conservation and Planning. Alan Doby. Hutchinson — The Built Environment. 1978. 173 pages. Some illustrations. Paper back, £3.25.

A Study in Conservation. Winston Barnett and Cyril Winskell. Oriel Press, 1977. 45 pages, in English, French and German. Illustrated. Paper back, £3.75.

Interpreting the Conserved Environment. Working Paper No. 29. Brian Goodey. Oxford Polytechnic Department of Town and Country Planning, 1977. 65 pages. Paper back, not priced.

“Belgium”, R. Riley, £3.25, 205 pp.

“The Netherlands”, D. Pinder, £3.25, 194 pp.

“The USSR”, J. C. Dewdney, £3.25, 262 pp.

Development Strategy of Bangladesh

Nurul Islam

Oxford, Pergamon Press, 1978, 109 pp.  相似文献   

428.
An extracellular fraction from the lignin degrading white-rot fungus, Coriolus versicolor, can biosolubilize leonardite and pretreated lignites in vitro. Leonardite is often found as an overburden to lignite deposits, and is related to humic acid, and is more oxidized than lignites. Extracts from certain fungi such as C. versicolor solubilize leonardite. The biosolubilization activity is at least in part enzymatic in nature. A protein which is at least partly responsible for the solubilization effect has been substantially purified and concentrated by ultrafiltration and ion-exchange chromatography from the broth of an agitated submerged culture of C. versicolor grown in a defined medium. An in vitro coal biosolubilization assay was used to establish the effects of various physical and chemical factors affecting enzyme activity, including temperature and the salt and buffer composition of the reaction mixture. Some initial studies on the mechanism of the enzymatic leonardite biosolubilization reaction are described.  相似文献   
429.
ABSTRACT: Nine surface water‐quality variables were analyzed for trend at 180 Virginia locations over the 1978 to 1995 period. Median values and seasonal Kendall's tau, a trend indicator statistic, were generated for dissolved oxygen saturation (DO), biochemical oxygen demand (BOD), pH (PH), total residue (TR), nonfilterable residue (NFR), nitrate‐nitrite nitrogen (NN), total Kjeldahl nitrogen (TKN), total phosphorus (TP), and fecal coliform (FC) at each location. Each location was assigned to one of four physiographic regions, and mean state and regional medians and taus were calculated. Widespread BOD and NFR improvements were detected and FC improvements occurred in the state's western regions. TR and TKN exhibited predominantly increasing trends at locations throughout the state. BOD, TKN, NFR, and TR medians were higher at coastal locations than in other regions. NN, TKN, and TR exhibited predominantly increasing trends in regions with high median concentrations, while declining trends predominated in regions with relatively high BOD, FC, and NFR medians. Appalachian locations exhibited the greatest regional water‐quality improvements for BOD, FC, NFR, and TKN. Factors responsible for regional differences appear to include geology, land use, and landscape features; these factors vary regionally.  相似文献   
430.
Micro-zooplankton populations in the upper 100 m were sampled from 5 marine environments in the northeast Pacific Ocean extending from slope waters off San Diego to an oceanic site near Isla Guadalupe, and their abundance related to that of the larger zooplankton, phytoplankton (as estimated from chlorophyll a), and detritus. The micro-zooplankton and other components of the seston were subdivided into 3 fractions on the basis of size in the deck-mounted collecting unit of a seawater pumping system. Through the euphotic zone at each site, the Protozoa, of which ciliates were the dominant forms, accounted for 95% or more of the total micro-zooplankton numbers. Their biomass, as volume, was estimated to be 13 to 28% of that of the total micro-zooplankton. The standing stock of micro-zooplankton over the euphotic zone at the various sites, in terms of dry weight, was estimated to be 14 to 34% (average 23%) of that of the phytoplankton crop. Micro-zooplankton volumes in the upper 100 m were 21 to 26% of those for the larger zooplankton sampled over the same depth.  相似文献   
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