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41.
S. Walker BSc PhD CEng FICE H. A. Smithers BSc MSc 《Water and Environment Journal》1998,12(4):273-279
As environmental regulator, the Environment Agency seeks the best balance between essential needs of water supply and the environment, whilst taking into account costs and benefits; nowhere is this balance more focused than in the management of droughts. The drought of 1995–96 was the most severe on record in the North West, and presented a major challenge to both the water company and the Environment Agency in safeguarding essential water supplies and minimizing the risks to the environment.
This paper describes the management of the drought from the Agency's perspective. 相似文献
This paper describes the management of the drought from the Agency's perspective. 相似文献
42.
P. K. Bishop BSc PhD CGeol FGS B. D. Misstear BA MSc CGeol FGS CEng MIEI M. White BSc CEng MICE N. J. Harding BSc 《Water and Environment Journal》1998,12(3):216-223
This paper summarizes the findings of a recent research project on groundwater contamination from leaking sewers, which was completed for the Construction Industry Research and Information Association. Fifty-four incidents were identified in England and Wales from a combined questionnaire survey and literature review. In addition to recorded incidents, the poor quality of many urban groundwaters suggests some effects from leaking sewers. Age is considered to be the most significant characteristic governing leakage from sewers; ground conditions (predominantly aquifer vulnerability) and usage (private versus public ownership) are also important factors relating to the likelihood of groundwater pollution from leaking sewers. Recommended strategies for reducing groundwater contamination include (a) modification of existing criteria for the service performance grading of existing sewers, (b) improved construction of new sewers in appropriate areas, (c) increased groundwater monitoring, and (d) risk assessments for new groundwater sources. 相似文献
43.
The paper reviews the regulation of water companies in England and Wales since 1989 by reference to the historical regulation of utilities in these countries. It considers how comparative competition, service standards and charging arrangements are developing. Particular mention is made of the debates over rates of return and household metering. The conclusion is that regulation, to be effective and appropriate, must be capable of evolution. 相似文献
44.
The paper outlines the statutory arrangements governing water and sewerage charges in Scotland, and comments on the factors affecting the levels of charges. Trends in revenue expenditure over the period 1989–90 to 1992–93 are considered in relation to increases in personal community water charge levels, metered water rates, and costs per household. Non-domestic sewerage rates and industrial effluent charges are also discussed. Some comparisons are made with England and Wales and with other countries. The funding arrangements for capital expenditure and their effect on the levels of charges are described, with particular reference to debt levels and rising expenditure to meet UK and EC standards. Factors affecting future charge levels are also identified. 相似文献
45.
D. D. Mara PhD DSc Eurlng CEng FICE CBiol FIBiol FRIPH 《Water and Environment Journal》2004,18(4):230-234
The design of septic tanks, constructed wetlands, waste-stabilisation ponds and rock filters is detailed, and their applicability in the UK is discussed. Septic tanks are a suitable primary treatment system for villages with a population of less than 500. Constructed wetlands, which are secondary or tertiary treatment units, have the disadvantage that their plants do not play any significant role in their performance, except for nitrogen removal. Secondary facultative waste-stabilisation ponds, with pre-treatment in septic tanks and post-treatment in rock filters, provide primary, secondary and tertiary treatment and can produce high-quality effluents. The costs of these processes for small rural communities in the UK are compared. 相似文献
46.
A novel peatland management strategy to utilise the high nutrient-retention potential of degenerated peatlands has been implemented in Northern Germany. The effect of raised water levels and extensive land-use management on hydraulic properties, water quality and vegetation characteristics of heavily vegetated and groundwater-fed open ditches, was investigated at the River Elder Valley - a nationally important wetland case study. A better understanding of the effect of vegetation on the temporal flow patterns and the hydraulic retention times is of high scientific interest, especially for improving nutrient standards in lowland rivers. Within-ditch vegetation and other hydraulic obstructions, including accumulated silt and organic debris, increase the hydraulic retention time and lead to an improvement of the water quality along the open ditch. Lower parts of the open ditches were flooded by the River Elder, due to the absence of a mowing scheme during late summer 相似文献
47.
This paper reviews methods of estimating recharge for a wide variety of aquifers in Britain. A soil moisture balance technique is used with direct representation of relevant soil and crop properties. Recharge contributions due to rainfall, runoff from impervious areas and leaking water mains and sewers are considered. In many field situations low permeability strata, which overlie the main aquifer, modify the timing and magnitude of the actual recharge. Runoff from less permeable strata can become runoff-recharge at the aquifer outcrop. Reference is made to several case studies. 相似文献
48.
A. Brookes BSc PhD FRGS MIEMA A. Chalmers MEng R. Vivash CEng MICE 《Water and Environment Journal》2005,19(3):199-206
The Tlimore Brook, In Hampshire, typifies the Impact of new housing development that has taken place In phases over the past 20 years or so, on a river corridor. However, the issue is not one of flooding, because the channel itself had been straightened and deepened in historical times and had been adjusted further by down-cutting; thereby forming an over-large channel sufficient to contain flood flows. Perhaps rarely for lowland Britain, the key problem was that of erosion, threatening adjacent properties. This paper describes the nature of the erosion problem and the subsequent geomorphological design to mitigate it. A key unique feature of this project was the extent of backfilling required, over the entire length, to raise the over-deep channel bed. The project was constructed in 2003. 相似文献
49.
A model was developed and tested to investigate the effects of various parameters on the processing costs of anaerobic digestion. The model was based on empirical data collected from full-scale plants which varied in size from 35,000 to 900,000 population equivalents. (Equivalent to loading rates of 0.5 to 2.7 kg VS/m3 /d.) In spite of different operating regimes and conditions of the plants analysed, various relationships were discovered between: sludge quality and volatile solids destruction; sludge quality and biogas yield; and, effluent volatile solids and dewatering. Where correlations existed, these were used to make predictions on operating costs of the digestion and dewatering plant based on sensitivity analysis. The results of the model were used to make recommendations on how to optimise the operation of an anaerobic digestion plant. 相似文献
50.
The EC bathing water Directive and the recent EC urban waste water treatment Directive have provided, and will continue to provide, a strong stimulus for the provision of environmental improvement through the upgrading of sewerage assets. The positive response by Lothian Regional Council to necessary improvements in the last fifteen years, and the proposed improvements in the next fifteen years, are reviewed against the background of financial constraints. It is suggested that parts of the urban waste water treatment Directive relating to estuarial and coastal discharges are not appropriate or necessary in the context of conditions in Lothian Region. 相似文献