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排序方式: 共有328条查询结果,搜索用时 46 毫秒
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The Science of Nature - 相似文献
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Gabi Förtsch Helmut Krinn Gabi Mai Heinz Meinholz Michael Pleikies 《Environmental Sciences Europe》1996,8(5):293-299
Economic regulations on recycling and respective waste disposal legislation will increasingly demand the realization of new waste management concepts. They do not stem from a ministerial goal in itself, but instead offen the enterprizes a chance to develop their own waste disposal strategies with a goal toward the future. In the course of an Intra-company analysis, this waste disposal concept must take the operative organization, the relevant processes and manufacturing techniques, the accumulation of waste in the cost centers as well as the waste disposal and utilization into consideration. Fundamental principles include the environmental regulations applicable to the enterprize in the form of both federal decress and injunctions. An environmental examination report demonstrates the methodical possiblities for stock-taking and makes it possible to identify the measures necessary for improving the operational waste disposal situation. The mandatory data acquisition and a feasible waste monitoring network can be used in the course of environmental management system for making an expert opinion by an independent, reputable environmental verifier. 相似文献
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J. R. Krebs 《Behavioral ecology and sociobiology》1976,1(2):215-227
Summary This paper is concerned with the idea that the song repertoires of passerine birds are an evolutionary adaptation to reduce habituation in listeners. In an experiment involving 16 territorial males I played either a single song or a repertoire of songs for 15 two-min trials through a single loudspeaker near the edge of the territory. In a second experiment with 10 birds I played the songs through one of two loudspeakers in different parts of the territory, alternating between loudspeakers on successive trials. The birds tended to habituate more rapidly to single song playback than to repertoires. In the second experiment the overall level of habituation was lower and the difference between the two treatments was less marked.Two features of song repertoire organisation are consistent with the habituation hypothesis (1) the avoidance of low recurrence intervals in switches between song types, and (2) the fact that within repertoire variability is as great or greater than between repertoire varability.The main problem with the habituation hypothesis is that habituation by listeners does not seem to be adaptive, so it is not clear why they should habituate. I suggest a hypothesis. Intruders may assess the density of birds in an area by listening to songs, so that habituation may be a mechanism by which this density assessment is achieved. Repertoires could be a mechanism by which resident birds cheat, through increasing the apparent density of singing birds. 相似文献
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The Science of Nature - 相似文献
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Animal Meal: Production and Determination in Feedstuffs and the Origin of Bovine Spongiform Encephalopathy 总被引:1,自引:0,他引:1
Hahn H 《Die Naturwissenschaften》1999,86(2):62-70
This contribution examines what animal meal is, how it is produced in rendering plants, and means of investigating feedstuff constituents. In addition to animal meal, numerous other products of animal origin are also on the market (e.g., blood meal, bone meal, feather meal, gelatin). Constituents of animal origin can be detected in feedstuffs by microscopy, but determining the animal species from which the constituents are derived, as required by law in Germany, requires methods such as enzyme-linked immunosorbent assay and polymerase chain reaction. We consider the problem of trace contamination being introduced accidentally during the production of ruminants feedstuffs containing constituents of animal origin. The future of animal meal is discussed together with alternatives for disposing of animal carcasses and slaughtery offal, i.e., composting and incineration. 相似文献
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