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For drinking water security the German waterworks proceed on a comprehensive concept, i.e., the protection of all the regions from the recharge area to the client. It includes the protection of the recharge area by a precautionary management, a safe water treatment, a strict maintenance of the water distribution network, continuous control and an intensive training of staff. Groundwater protection zones together with effective regulations and control play a very important role. Three protection zones with different restrictions in land-use are distinguished. Water in reservoirs and lakes is also protected by Surface Water Protection Zones. Within the surrounding area the land-use is controlled, too. Special treatment is necessary if acidification happens caused by acid rain, or eutrophication caused by the inflow of sewage. Very important is the collaboration between waterworks and the farmers cultivating land in the recharge area in order to execute water-protecting ecological farming with the aim to reduce the application of fertilizers and plant protection agents. Probable financial losses have to be compensated by the waterworks.  相似文献   
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The present drinking water purification system in Egypt Uses surface water as a raw water supply without a pre-liminary filtration process.On the other hand,chlorine gas iS added as a disinfectant agent in two steps,pre- and post.chlorination.Due to these reasons most of water treatment plants suffer low fltering effectiveness and produce the trihalomethane (THM) species as a chlorination by-product.The Ismailia Canal represents the most distal downstream of the main Nile Rivet.ThUS its water contains all the proceeded pollutants discharged into the Nile.In addition.the downstream reaches of the canal act as an agricultural drain during the closing period of the High Dam gates in January and February every year.Moreover,the wide in-dustrial zone along the upstream course of the carlal enriches the canal water with high concentrations of heavy metals.The obtained results indicate that the canal gains up to 24.06×106m3 of water from the surrounding shallow aquifer during the closing period ofthe High Dam gates,while during the rest ofthe year,the callal acts as an influent stream losing about 99.6×106m3 of its water budget.The reduction oftotaI organic carbon(TOC) and suspended particulate mattes(SPMs)should be one of the central goals of any treatment plan to avoid the disinfectants by-products.The combination of sedimentation basins.gravel pre-filtration and slow sand filtration,and underground passage with microbiological oxidation-reduction and adsorption criteria showed good removal of parasites and bacteria and complete elimination of TOC.SPM and heavy metals.Moreover,it reduces the use of disinfectants chemicals and lowers the treatment costs.However,this purification system under the arid climate prevailing in Egypt should be tested and modified prior to application.  相似文献   
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Little is known about entertainment acquisition and production, especially the international format trade, although its worldwide market volume adds up to about 2.4 billion. Format trade is a process along the stages of creating, distributing, producing or reproducing, and broadcasting entertainment programs. Findings of a current empirical research project conducted by means of in-person interviews with managers in Germany and the United Kingdom reveal a phenomenon by which the particular organizations involved (creators, distributors, producers, and broadcast stations) establish structures that are called “flowing organizational networks.” Depending on situational requirements and the respective stages of the format trade process, actors tend to activate different organizational structures.  相似文献   
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Distance higher education is one of the characteristic features of changes in the structures of higher education, which took place when demand for study places could not be met by the traditional “non‐distance” institutions of higher education. Further development of this forms is of great interest, especially in view of the tasks and problems facing contemporary and future higher education

In this context, we present below the article written for “Higher Education in Europe” by Dr. Klaus‐Dieter Grunwald from the Federal Ministry of Education and Science, Bonn, which present development and functioning of distance study in Federal Republic of Germany on the example of the Fernuniversität‐Gesamthochschule in Hagen.  相似文献   

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Starting from a general framework for web-based e-learning systems that is based on an abstraction layer model, this paper presents a conceptual modelling approach, which captures the modelling of learners, the modelling of courses, the personalisation of courses, and the management of data in e-learning systems. Courses are modelled by outline graphs, which are further refined by some form of process algebra. The linguistic analysis of word fields referring to an application domain helps to set up these course outlines. Learners are modelled by classifying value combinations for their characteristic properties. Each learner type gives rise to intentions as well as rights and obligations in using a learning system. Intentions can be formalised as postconditions, while rights and obligations lead to deontic constraints. The intentions can be used for the personalisation of the learning system to a learner type. Finally, the management of data in an e-learning system is approached on two different levels dealing with the content of individual learning units and the integrated content of the whole system, respectively. This leads to supporting databases and views defined on them.  相似文献   
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Worldwide, several regions suffer from water scarcity and contamination. The infiltration and subsurface storage of rain and fiver water can reduce water stress. Artificial groundwater recharge, possibly combined with bank filtration, plant puri- fication and/or the use of subsurface dams and artificial aquifers, is especially advantageous in areas where layers of gravel and sand exist below the earth's surface. Artificial infiltration of surface water into the uppermost aquifer has qualitative and quanti-tative advantages. The contamination of infiltrated fiver water will be reduced by natural attenuation. Clay minerals, iron hy-droxide and humic matter as well as microorganisms located in the subsurface have high decontamination capacities. By this, a final water treatment, if necessary, becomes much easier and cheaper. The quantitative effect concerns the seasonally changing fiver discharge that influences the possibility of water extraction for drinking water purposes. Such changes can be equalised by seasonally adapted infiltration/extraction of water in/out of the aquifer according to the fiver discharge and the water need. This method enables a continuous water supply over the whole year. Generally, artificially recharged groundwater is better protected against pollution than surface water, and the delimitation of water protection zones makes it even more save.  相似文献   
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