全文获取类型
收费全文 | 102篇 |
免费 | 3篇 |
专业分类
大气科学 | 1篇 |
地球物理 | 35篇 |
地质学 | 48篇 |
海洋学 | 4篇 |
天文学 | 1篇 |
自然地理 | 16篇 |
出版年
2021年 | 2篇 |
2020年 | 5篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2016年 | 3篇 |
2015年 | 5篇 |
2014年 | 1篇 |
2013年 | 3篇 |
2012年 | 8篇 |
2011年 | 9篇 |
2010年 | 5篇 |
2009年 | 5篇 |
2008年 | 6篇 |
2007年 | 7篇 |
2006年 | 4篇 |
2005年 | 4篇 |
2004年 | 3篇 |
2003年 | 6篇 |
2002年 | 6篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有105条查询结果,搜索用时 15 毫秒
1.
Skier-triggered avalanches are the main cause of avalanche accidents in backcountry skiing. The risk of accidents during backcountry
skiing was analysed statistically and related to factors such as elevation level, aspect, stability rating and the time of
the year. The analysis is based on a database about terrain usage and avalanche accidents from a large heli-skiing operator
in Canada, which makes it possible to study the conditional probability of accidents given the recorded pattern of terrain
usage. This study shows that the historical risk of accidentally triggering an avalanche greater than size 1 depends highly
on the stability rating, with the highest risk occurring during “poor” stability. The risk is greater at high elevations,
and it is lower during the late season than earlier on. Skier risk does not depend as much on aspect as may be indicated from
avalanche data alone. However, it is relatively high in the N–NE–E sector. These factors are not independent of each other
and therefore analyses of combined factors were also performed. Questionnaires and interviews were used to gain knowledge
about the terrain selection of professional mountain guides. These results indicate that when selecting terrain, guides first
look at the overall shape and size of the terrain, but avalanche history of terrain and inclination are also important factors.
Finally, remarks in avalanche reports were analysed, and common human factors identified. 相似文献
2.
Studies evaluating the reproductive pattern of Mytilus edulis L. were conducted in western and eastern Iceland at two sites at about the same latitude but with different temperature regimes. Mussels were sampled once or sometimes twice a month during two years in Breidifjördur, western Iceland and one year at Mjoifjördur, eastern Iceland. Gonad development was monitored by microscopic observation of thin sections of the gonads. The initiation of gonad development was observed in January in Breidifjördur while in Mjoifjördur some of the animals started developing gonads in October, a month before spawning was over in the population. Spawning started in late June or July, peaked in August and continued until November at both sites. Nutrient reserve stores seemed to be limited and used for initiation of gonad development in winter but were not sufficient for maturation of the gonads. The main growth of the gonads occured in spring in conjunction with phytoplankton blooming and renewal of food resources. 相似文献
3.
Amy E. Clifton Carolina Pagli Jna Finndís Jnsdttir Kristjana Eythorsdttir Kristin Vogfjr 《Tectonophysics》2003,369(3-4):145-154
Three large earthquakes (Mw>4.5) were triggered within 5 min, 85 km west of a Mw 6.5 earthquake in the South Iceland Seismic Zone (SISZ). We report on surface effects of these triggered earthquakes, which include fresh rupture, widespread rockfall, disrupted rockslides and block slides. Field data confirm that the earthquakes occurred along N-striking right-lateral strike-slip faults. Field data also support the conclusion from modeling of InSAR data that deformation from the second triggered event was more significant than for the other two. A major hydrological effect was the draining of water through an open fissure on a lake bed, lowering the lake level by greater than 4 m. Field relationships suggest that a component of aseismic slip could have been facilitated by water draining into the fault zone. 相似文献
4.
Reinterpretation of the RRISP-77 Iceland shear-wave profiles 总被引:1,自引:0,他引:1
5.
Daníel Freyr Jónsson Esther Ruth Gudmundsdóttir Gudrún Larsen Bergrún Arna Óladóttir Egill Erlendsson Sigrún Dögg Eddudóttir Olgeir Sigmarsson 《第四纪科学杂志》2020,35(3):410-421
Large Plinian eruptions from Hekla volcano, Iceland, produce compositionally zoned tephra used as key markers in tephrochronology. However, spatial variations in chemical composition of a tephra layer may complicate its identification. An example is the 5950–6180 cal a bp Hekla Ö tephra layer, which shows compositional spread from rhyolite, dacite and andesite to basalt. In soil sections north of Hekla, the SiO2 content of the tephra glass reaches 76 wt% in the lowest unit of the Hekla Ö deposit and decreases to 62–63 wt% in the uppermost unit. Intermingled within the whole deposit are basalt tephra grains having 46–47 wt% SiO2. The composition of the basalt glass includes primitive basalt and a more evolved basalt (MgO >6 and <6 wt%, respectively). Together with literature data, the Hekla Ö tephra and the so-called T-Tephra/Hekla-T are most likely from contemporaneous eruptions of different vents on the Hekla volcanic system, forming a single important marker tephra (Hekla ÖT) deposited over 80% of Iceland. Identification is complicated by its spatial compositional heterogeneity, such as systematic decrease in SiO2 content from the east to the west of Hekla volcano. Consequently, an individual tephra layer from a large explosive eruption can have different composition at different locations. © 2020 John Wiley & Sons, Ltd. 相似文献
6.
Urban floods pose a societal and economical risk. This study evaluated the risk and hydro-meteorological conditions that cause pluvial flooding in coastal cities in a cold climate. Twenty years of insurance claims data and up to 97 years of meteorological data were analysed for Reykjavík, Iceland (64.15°N; <100 m above sea level). One third of the city's wastewater collection system is combined, and pipe grades vary from 0.5% to 10%. Results highlight semi-intensive rain (<7 mm/h; ≤3 year return period) in conjunction with snow and frozen ground as the main cause for urban flood risk in a climate which undergoes frequent snow and frost cycles (avg. 13 and 19 per season, respectively). Floods in winter were more common, more severe and affected a greater number of neighbourhoods than during summer. High runoff volumes together with debris remobilized with high winds challenged the capacity of wastewater systems regardless of their age or type (combined vs. separate). The two key determinants for the number of insurance claims were antecedent frost depth and total precipitation volume per event. Two pluvial regimes were particularly problematic: long duration (13–25 h), late peaking rain on snow (RoS), where snowmelt enhanced the runoff intensity, elongated and connected independent rainfall into a singular, more voluminous (20–76 mm) event; shorter duration (7–9 h), more intensive precipitation that evolved from snow to rain. Closely timed RoS and cooling were believed to trigger frost formation. A positive trend was detected in the average seasonal snow depth and volume of rain and snowmelt during RoS events. More emphasis, therefore, needs to be placed on designing and operating urban drainage infrastructure with regard to RoS co-acting with frozen ground. Furthermore, more detailed, routine monitoring of snow and soil conditions is important to predict RoS flood events. 相似文献
7.
8.
Climate change and human impact in a sensitive ecosystem: the Holocene environment of the Northwest Icelandic highland margin 总被引:1,自引:0,他引:1 下载免费PDF全文
Sigrún D. Eddudóttir Egill Erlendsson Leone Tinganelli Guðrún Gísladóttir 《Boreas: An International Journal of Quaternary Research》2016,45(4):715-728
Complex interactions of climate and volcanic activity have shaped the environment of Iceland during the Holocene. Palaeoecological records from Iceland offer a unique look at a Holocene environment that was uninhabited by humans and free of mammal herbivores until about AD 870. We present a new reconstruction of Holocene vegetation and landscape dynamics from a small lake, Barðalækjartjörn, located near the highland margin in Northwest Iceland. A multi‐proxy approach was used to reconstruct vegetation based on pollen and plant macrofossil analysis and landscape stability based on lithological proxies. The record covers the period c. 10 300–200 cal. a BP. For the first two millennia aeolian processes probably played a part in vegetation development. This period is characterized by high input of minerogenic material into the lake and a vegetation assemblage in which plants tolerant of aeolian deposition are prominent. Betula pubescens woodland reached a maximum between c. 7400 and 6500 cal. a BP. Betula nana‐dominated dwarf shrub heath replaced woodland after c. 4000 cal. a BP, following the onset of Neoglaciation. Land use following human settlement caused an environmental shift at the highland margin. Betula pubescens probably disappeared from the vicinity of the lake soon thereafter. Large‐scale soil erosion began at c. 1000 cal. a BP in the wake of human activities, such as introduction of grazing livestock and woodcutting. This study offers an important long‐term perspective of the development of the highland ecosystem under both wholly natural and human‐influenced conditions. 相似文献
9.
The present study is the first to compare trophic relationships of several co-occurring phytal harpacticoid species, in their natural habitat, using both δ13C and δ15N signatures. Three phytal harpacticoid species/taxa (Zaus spinatus, Tisbe spp., and Parathalestris cf. intermedia) all collected from the alga Fucus serratus, at different times of the year, were analyzed. The results indicated that the harpacticoids were utilizing food sources differently. Specific food sources of the three species/taxa could not be accurately pinpointed, but there were strong indications that F. serratus and fragments from it did contribute significantly to the diet of P. cf. intermedia and Tisbe spp. Both of these harpacticoid species overlapped in δ13C and δ15N values with some of the macrofaunal species, collected from the same site in Hvassahraun, Iceland, while no overlap was seen for Z. spinatus. The signatures for Z. spinatus indicated that its food sources changed seasonally. 相似文献
10.
rnýErla Sveinbjrnsdttir 《Lithos》1991,27(4):301-315
In high temperature geothermal areas (T.200°C) in Iceland the alteration minerals formed show a regular zoning with increasing temperature i.e. smectite, chlorite, epidote and actinolite. To test the effect of varying composition of the hydrothermal circulation fluid drillhole chips from two contrasting areas were analyzed in detail. The Reykjanes area is fed with sea water while Krafla is fed with meteoric water and has a Cl− concentration of 28 ppm. Both areas have tholeiitic basalts, lavas and hyaloclastites as original reservoir rocks.
Although both systems have the same sequence of alteration minerals the actual composition of the minerals differs between systems reflecting the different chemical composition of the circulating waters. In Reykjanes, with its brine fluid, the composition of the original rock appears not to affect the composition of the alteration minerals while the reverse appears to be the case in Krafla. 相似文献