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排序方式: 共有848条查询结果,搜索用时 31 毫秒
91.
The article analyses the results of the scheme for field afforestation (EU-regulation 2080/92) in Denmark. The purpose is twofold, firstly to document the afforestation on arable land taking place both within the scheme and outside the scheme for field afforestation. The former is documented in Ribe and Vejle counties whereas the latter is documented in three smaller areas: Varde, Vorbasse, and Vejle. Secondly, the article argues that in order to evaluate the afforestation not only the location within designated areas hut also the spatial parameters and configuration of new woodlands must be considered. Two methods -'forest-pictures' and ‘gradient-pictures’-are presented and applied in order to quantify the spatial configuration of new woodlands in the landscape.  相似文献   
92.
The concentrations of copper, zinc, cadmium, selenium and mercury were determined in eggs, muscle, liver, kidney and stomach content of nestilings and adults of the Antarctic petrel, Thalassoica antarctica, and its predator, the south polar skua, Chataracta maccormicki, from Svarthamaren, Dronning Maud Land, Antarctica. The dominant food of the petrels is krill, Euphausia superba. The results show relatively high levels of cadmium in krill, which is assumed to be the main reason for the high levels of cadmium in petrels and skuas. Cadmium is almost absent in eggs, but accumulates very rapidly with age in nestlings. The copper concentrations in livers of nestling petrels reach very high levels during growth. This may be seen in connection with physiological development processes. Mercury seems to be accumulated with age and between trophic levels. Among the nestlings, the mercury levels decrease with increasing age, which may be accomplished by the excretion of mercury through the growth of feathers and as a dilution effect during growth. Selenium and mercury are inversely correlated in nestlings. The levels of zinc were similar for different nestling stages and between nestlings and adults in skuas and petrels.  相似文献   
93.
A simple model for the equilibrium spectra of velocity fluctuations in the unstable surface layer is developed. All three component spectra are written as a sum of two spectra For the horizontal spectra, the two parts scale with % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqaqpepeea0xe9qqVa0l% b9peea0lb9Lq-JfrVkFHe9peea0dXdarVe0Fb9pgea0xa9W8qr0-vr% 0-viWZqaceaabiGaciaacaqabeaadaqaaqaaaOqaaiaacIcacaWGUb% GaamOEamaaBaaaleaacaWGPbaabeaakiaac+cacaWG1bGaaiilaiaa% dQhadaWgaaWcbaGaamyAaaqabaGccaGGVaGaamitaiaacMcaaaa!4232!\[(nz_i /u,z_i /L)\]and % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqaqpepeea0xe9qqVa0l% b9peea0lb9Lq-JfrVkFHe9peea0dXdarVe0Fb9pgea0xa9W8qr0-vr% 0-viWZqaceaabiGaciaacaqabeaadaqaaqaaaOqaaiaad6gacaWG6b% Gaai4laiaadwhaaaa!3B5E!\[nz/u\], respectively; the vertical spectrum can be written entirely as a function of % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqaqpepeea0xe9qqVa0l% b9peea0lb9Lq-JfrVkFHe9peea0dXdarVe0Fb9pgea0xa9W8qr0-vr% 0-viWZqaceaabiGaciaacaqabeaadaqaaqaaaOqaaiaad6gacaWG6b% Gaai4laiaadwhaaaa!3B5E!\[nz/u\] and % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqaqpepeea0xe9qqVa0l% b9peea0lb9Lq-JfrVkFHe9peea0dXdarVe0Fb9pgea0xa9W8qr0-vr% 0-viWZqaceaabiGaciaacaqabeaadaqaaqaaaOqaaiaadQhacaGGVa% Gaamitaaaa!3A42!\[z/L\].The equilibrium spectra are utilized as part of a model describing the development of velocity spectra downwind of a change in surface roughness and heat flux.Results are shown for the streamwise component and compared with hotwire measurements from the RISØ 78 experiment. The model shows excellent agreement with the measurements.on leave of absence from RISØ National Laboratory Roskilde, Denmark.  相似文献   
94.
The authors surveyed a representative sample of the Norwegian population (N = 4077) to examine perceptions of biodiversity loss and management, the relative importance of biodiversity loss to other environmental issues, and perceived implications of biodiversity loss. The results showed that 50% of the sample population saw biodiversity as a reality and major environmental issue, and 75% recognized that biodiversity loss occurs. Biodiversity loss was perceived as a lesser global environmental problem than environmental toxins, climate change, air and water pollution, and loss of rainforest, despite the fact that these topics can be difficult to separate since biodiversity loss is a function of other environmental problems. Loss of biodiversity was seen to have negative impacts on people's relationship to the natural environment, to impact environmental resilience, to be at least partly human-induced, and to be an issue of importance and relevance to the general public, not merely to the scientific community. Self-reported levels of knowledge of environmental topics were associated with increasing concern about consequences of reductions in species diversity. The authors conclude that efforts to increase public support for biodiversity conservation can be strengthened by increased emphasis on aesthetic, emotional and cultural aspects of biodiversity.  相似文献   
95.
96.
白宫推迟发布行政部门的科研诚信计划这一举动导致了最近的一场诉讼,并使公众产生对完善白宫2009年签署的科研诚信备忘录的担忧,尽管政府已采取了一些措施并在备忘录方面取得了进展。科研诚信备忘录发布于2009年3月9  相似文献   
97.
The Midgard Field offshore mid-Norway is a gas-condensate accumulation with a thin oil leg reservoired in Early and Middle Jurassic sandstones. There are two potential source rocks in the area; the Late Jurassic Spekk Formation is a marine shale with type II kerogen and a rich potential for oil, and the Åre Formation of Early Jurassic age which is a thick coal-bearing sequence with type III kerogen and potential mainly for gas. Geochemical analyses indicate that both the condensate and the oil leg are sourced mainly from the coal-bearing Åre Formation. Any contribution from the Spekk Formation appears to be of minor importance. Computer simulation of hydrocarbon generation in the drainage area for the Midgard Field indicates that huge volumes are formed, and confirms that hydrocarbon generation from the Åre Formation is volumetrically far more important than from the Spekk Formation. The simulation results also exclude any contribution to the reservoired gas from the Spekk Formation.
Zusammenfassung Das Midgard Feld vor der Küste Mittelnorwegens ist eine Gas-Kondensat-Akkumulation mit einem nur geringen Ölanteil innerhalb unter- und mitteljurassischer Sandsteine. In diesem Gebiet gibt es zwei mögliche Muttergesteine: Einmal die oberjurassische Spekk-Formation, bei der es sich um einen marinen Schiefer mit Typ II Kerogen handelt und die ein hohes Ölpotential darstellt. Zum anderen gibt es die unterjurassische Åre-Formation, eine mächtige Kohle-führende Folge mit Typ III Kerogen und ein möglicher Gaslieferant. Geochemische Analysen deuten darauf hin, daß sowohl das Gas-Kondensat als auch das Öl des Midgard Feldes auf diese Kohle-führende Åre-Formation zurückzuführen sind. Jede Zufuhr aus der Spekk-Formation scheint von geringer Bedeutung zu sein. Eine durch Computersimulation rekonstruierte Kohlenwasserstofferzeugung im Einzugsgebiet des Midgard Feldes spricht für eine hohe Bildungsrate und bestätigt die Annahme, daß die Kohlenwasserstoff-produktion der Spekk-Formation gegenüber der Åre-Formation zu vernachlässigen ist. Die Simulation ergab ferner, daß keinerlei Gas von der Spekk-Formation dem Reservoir zugeführt wurde.

Résumé Le champ off-shore de Midgard (Norvège moyenne) est une accumulation de gaz condensé accompagnée d'un mince corps d'huile, accumulation renfermée dans des grès d'âge jurassique inférieur et moyen. Il existe dans le secteur deux sources possibles: la formation de Spekk (shale marins du Jurassique tardif, à kérogène de type II, possédant un riche potentiel en huile) et la formation d'Åre (série épaisse jurassique inférieure, à couches de charbon, à kérogène de type III et potentiel essentiellement en gaz). Les analyses géochimiques montrent que le gaz condensé et l'huile ont tous deux comme origine la formation charbonneuse de Åre. La formation de Spekk ne semble être intervenue que de manière subordonnée. Une simulation par ordinateur de la genèse de l'hydrocarbure dans l'aire d'alimentation du champ de Midgard fait apparaître que des volumes importants ont été formés et confirme la large prépondérance de la formation de Åre parmi les roches-mères. De plus, cette simulation exclut toute expèce de contribution de la formation de Spekk dans la genèse du gaz.

Midgard / / . : Spekk — , 2, , Are , 3 . . . , Are. Spekk, , . Midgard , Are . , , Spekk .
  相似文献   
98.
Recently, the sediment stratigraphy and geochronology of the well‐known Palaeolithic site Byzovaya in northern Russia were investigated. New technological analyses of the artefacts suggest a Middle Palaeolithic Mousterian culture, and occupation by Neanderthals, not Modern humans as previously thought. We present here a new and detailed documentation of the stratigraphy, including the geological context of the artefacts and faunal remains. From sedimentological criteria we confidently interpret the find‐bearing strata as debris‐flow deposits, covered by aeolian sediments. The chronology is based on radiocarbon and luminescence (OSL) dates from the find‐bearing and overlying strata. The results are utilized to reconstruct the geological history at the excavation area. The stratigraphy varies considerably across the excavation area. The most intact and undisturbed part of the sequence was found inside the most recent Excavation II. In this part the artefacts and bones appear to have been permanently sealed and protected by aeolian sand. The older Excavation I shows a more complicated stratigraphy, as the finds may have been temporarily exposed during the early Holocene owing to ravine incision and slumping activity. The individual radiocarbon dates that were collected from different parts of the site and from various stratigraphic positions are re‐investigated in this study. By using Bayesian statistics the conclusion is that the site was occupied during a restricted period around 30.6–34.7 ka. A series of partly unpublished OSL dates of coversand from different sites demonstrates a regional aeolian signal during the Lateglacial in northern Russia, 15–14 ka.  相似文献   
99.
Trace element concentrations and contents in gills, gonad, kidneys, mantle, muscle and remainder during the reproductive cycle of female and male spiny and Pacific scallops, from the Strait of Georgia, BC, Canada, were quantified by using ICPMS. The elements investigated were chromium, manganese, iron, cobalt, nickel, selenium, molybdenum, cadmium, tin and mercury. For all ten elements, the tissue distribution was to some extent influenced by species, sex and reproductive status. The implications of the present study in relation to the design of biomonitoring programmes are: (1) care should be taken to ensure an equal/constant sex composition when making interannual comparisons of pooled samples. Preferably the sexes should be monitored separately. (2) the practice of obtaining pooled samples in the interspawn phase is applicable only to monitoring long-term trends in contaminant levels, while the reproductive status should be heeded when studying short-term changes. (3) the present study confirms that direct temporal or spatial comparisons of absolute accumulated element concentrations are only valid intraspecifically.  相似文献   
100.
Four drift accumulations have been identified on the continental margin of northern Norway; the Lofoten Drift, the Vesterålen Drift, the Nyk Drift and the Sklinnadjupet Drift. Based on seismic character these drifts were found to belong to two main groups; (1) mounded, elongated, upslope accretion drifts (Lofoten Drift, Vesterålen Drift and Nyk Drift), and (2) infilling drifts (Sklinnadjupet Drift). The drifts are located on the continental slope. Mainly surface and intermediate water circulation, contrary to many North Atlantic and Antarctic drifts that are related to bottom water circulation, and sediment availability have controlled their growth. Sediments were derived both from winnowing of the shelf and upper slope and from ice sheets when present on the shelf. The main source area was the Vøring margin. This explains the high maximum average sedimentation rate of the nearby Nyk (1.2 m/ka) and Sklinnadjupet (0.5 m/ka) Drifts compared with the distal Lofoten (0.036 m/ka) and Vesterålen (0.060 m/ka) Drifts. The high sedimentation rate of the Nyk Drift, deposited during the period between the late Saalian and the late Weichselian is of the same order of magnitude as previously reported for glacigenic slope sediments deposited during glacial maximum periods only. The Sklinnadjupet Drift is infilling a paleo-slide scar. The development of the infilling drift was possible due to the available accommodation space, a slide scar acting as a sediment trap. Based on the formation of diapirs originating from the Sklinnadjupet Drift sediments we infer these sediments to have a muddy composition with relatively high water content and low density, more easily liquefied and mobilised compared with the glacigenic diamictons.  相似文献   
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