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981.
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Summary. The effects of artificially added flavonoid aglycones to birch leaf surfaces on the larval performance of six species of leaf-chewing
sawflies were investigated. Significantly negative effects of increased contents of both total flavonoid and individually
fed flavonoid compounds were found for the larval performance of certain mid to late and late, but not early season, sawfly
species. Species-specific variations in the quantity of faecal flavonoid glycosides, which were examined to investigate whether
effective glycosylation of foliar flavonoid aglycones in larvae correlated with varying tolerance to these compounds, also
yielded significant species-specific differences between early and late season species. The results suggest seasonal adaptations
in host plant use by sawflies feeding on mountain birch, such that phenologically earlier species are better adapted to coping
with leaf surface flavonoid aglycones, which occur in the highest concentrations in young leaves. 相似文献
984.
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987.
Planners' and architects' knowledge of the needs of users as well as their perceptions of the residential environment, has been commented on in many studies dealing with residential satisfaction. In this study—based on primary research in an area of council housing in Madrid—the main goal is the study of objective and subjective factors, on both physical and social levels, which influence council housing residents' satisfaction. A sample of 447 housewives responded to a questionaire, a multiple regression analysis of which showed that attachment to the neighbourhood and relationships with neighbours explained the greatest variance in residential satisfaction. Some methodological issues about the measurement of residential satisfaction are also discussed. 相似文献
988.
Climatic records from equatorial eastern Africa and subtropical southern Africa have shown that both temperature and the amount
of rainfall have varied over the past millennium. Moreover, the rainfall pattern in these regions varied inversely over long
periods of time. Droughts started abruptly, were of multi-decadal to multi-centennial length and the changes in the hydrological
budget were of large amplitude. Changing water resources in semi-arid regions clearly must have regional influences on both
ecological and socio-economic processes. Through a detailed analysis of the historical and paleoclimatic evidence from southern
and eastern Africa covering the past millennium it is shown that, depending on the vulnerability of a society, climatic variability
can have an immense impact on societies, sometimes positive and sometimes disastrous. Therefore, the interconnected issue
of world ecosystem and social resilience is the challenge for decision-makers if sustainable development is to be reached
on global and local levels. 相似文献
989.
Kazimierz Klimek Maria Lanczont Jolanta Nogaj-Chachaj 《Regional Environmental Change》2006,6(1-2):52-61
The undulating loess Kanczuga Plateau, 250–270 m a.s.l., is located in the temperate climatic zone of Central Europe, within
the northern foreland of the Carpathians. It is dissected by a network of valleys 30–60 m deep, infilled with several metres
of complex minerogenic and organic deposits which started to accumulate during the early Holocene. The southern side of one
of these valleys is dissected by several dry valleys. The mouth sections of these valleys have buried surface comprising peat
and/or organic silts, overlain by sandy–silty alluvium. 14C dates indicate that the alluviation of these valley floors, which proceeded from the headwaters to the mouth sections, began
in the 1100 ad. The gradual intensification of soil erosion in the upper part of the catchment and associated sedimentation probably encompassed
only a few centuries, with greatest alluviation during the Little Ice Age. This plateau, which is under the influence of more
continental climatic conditions than the low-mountain and upland regions of Western Europe, features more climatic contrasts.
Here environmental changes triggered by land use were superimposed on climatic change. The most intensive processes of soil
erosion and sediment transfer as well as alluviation, coincided with the first phase of cooling during the Little Ice Age.
It was the final stage of the intensification of these processes, probably more intensive than its initial phase in the eleventh
century, caused primarily by deforestation resulting from the development of agriculture. 相似文献
990.
Maria Nowakowska Monika Sterzel Krzysztof Szczubiałka 《Journal of Polymers and the Environment》2006,14(1):59-64
Novel water-soluble polymeric photosensitizers based on a natural polymer, naphthalene-modified hydroxyethylcellulose (HENC),
were obtained and used for the photooxidation of cyanide. The reaction leads to the formation of cyanate. The process occurs
via photoinduced electron transfer from CN− to the naphthalene or naphthoquinone polymeric chromophores. The kinetics of the reaction depend on the degree of substitution
of HENC, its concentration, and pH of the solution. The polymers can be easily removed after reaction as prolonged irradiation
leads to their photodegradation. 相似文献