全文获取类型
收费全文 | 202篇 |
免费 | 3篇 |
国内免费 | 3篇 |
专业分类
测绘学 | 13篇 |
大气科学 | 18篇 |
地球物理 | 43篇 |
地质学 | 72篇 |
海洋学 | 30篇 |
天文学 | 21篇 |
自然地理 | 11篇 |
出版年
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 5篇 |
2015年 | 9篇 |
2013年 | 15篇 |
2012年 | 11篇 |
2011年 | 2篇 |
2010年 | 6篇 |
2009年 | 11篇 |
2008年 | 9篇 |
2007年 | 6篇 |
2006年 | 2篇 |
2005年 | 7篇 |
2004年 | 7篇 |
2003年 | 7篇 |
2002年 | 7篇 |
2001年 | 7篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1992年 | 2篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1986年 | 1篇 |
1985年 | 6篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 7篇 |
1974年 | 6篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1965年 | 1篇 |
1963年 | 2篇 |
1962年 | 2篇 |
1958年 | 1篇 |
1956年 | 1篇 |
1951年 | 1篇 |
1934年 | 1篇 |
排序方式: 共有208条查询结果,搜索用时 31 毫秒
91.
Arne Eide 《Climatic change》2008,87(1-2):251-262
The Barents Sea area is characterised by a highly fluctuating physical environment causing substantial variations in the ecosystems
and fisheries depending upon this. Simulations assuming different management regimes have been carried out to study how physical
and biological effects of global warming influence the Barents Sea cod fisheries. A regional, high-resolution representation
of the B2 world region (OECD90) scenario from the Intergovernmental Panel on Climate Change was used to calculate water temperatures
and plankton biomasses by hydrodynamic modelling. These results were included in simulations performed by a multi-fleet, multi-species
model, by which a fully integrated model linking to the global circulation model to the Barents Sea fisheries through a regional
downscaling to the Barents Sea area is constructed. One factor of particular importance for the natural annual biological
variations is the occasional inflow of young herring into the Barents Sea area. The herring inflow is difficult to predict
and links to dynamical systems outside the Barents Sea area, complex recruitment mechanisms and oceanographic conditions.
These processes are in the study represented by a stochastic representation of herring inflow based on historical observations.
According to the performed simulations the biomass fluctuations may slightly increase over the next 25 years, possibly caused
by changes in temperature patterns. Six different management regimes have been included in the study and the results support
earlier studies claiming that the choice of management regime potentially has a greater importance for biological and economic
performance in the Barents Sea fisheries than impacts which derive from global warming over the next 25 years. A basic assumption
for this conclusion is however that the Barents Sea ecosystem essentially preserves its structure and composition of today.
Possible, unpredictable significant shifts in the ecosystem structure are not considered. 相似文献
92.
Counter-slopes in avalanche paths influence avalanche flow in similarways as defence structures. Measurements and calculations of run-outon such slopes will improve our understanding of retaining damdesign. We have studied three different, well described avalancheevents; for each case we have calculated the run-out distance usingthe Noren, Irgens and Schieldrops continuum model (NIS), adjustingthe parameters to fit the simulated avalancheto the observed one. Using the same parameters, the run-out onidentical terrain, but without counter-slope, is computed. Comparisonbetween the energy dissipation in these different cases tells us whichtopography most efficiently retards an avalanche. With a smoothly curved valley bottom, the energy dissipation at agiven point on the opposite slope is less than on a flatrun-out. The explanation to this is that, when gravity retards anavalanche, a smaller portion of the energy loss is due to dissipationfrom viscous (velocity dependent) friction. When the avalanche travelsover a retaining dam, with much smaller curvature radii, a significantportion of the energy is dissipated. The consequence of this is that defence structures are not sodependent on the counter-slope inclination as on the curvature radiusin the transition to up-gradient. Further, introduction of acounter-slope in an avalanche path may conserve energy rather thancausing dissipation – if the inclination is not altered abruptlyenough. If the counter-slope is smooth, and not large enough tocompletely stop the avalanche, it will not reduce destructive energyon the downstream side. In fact, the destructive energy may bepartially conserved until the run-out. 相似文献
93.
The main results of Whitham's averaged Lagrangian method for the treatment of linear wave-trains in a weakly inhomogeneous, moving medium are presented briefly. This method is then applied to an ideal, isotropic, one-fluid plasma which can be taken for the lowest order approximation for the interplanetary solar wind expansion. 相似文献
94.
Von Arne von kraft Willy Nümann Hans M. Peters 《Aquatic Sciences - Research Across Boundaries》1963,25(1):84-118
Ohne Zusammenfassung
Herrn Prof. Dr. P. Meyer-Waarden zum 60. Geburtstag gewidmet
Mit Unterstützung des Ministeriums für Ern?hrung, Landwirtschaft und Forsten, Baden-Württemberg, und des Bayerischen Staatsministeriums
für Ern?hrung, Landwirtschaft und Forsten. 相似文献
95.
Arne Bjerhammar 《Journal of Geodesy》1962,36(3):215-220
Summary The principal formulae of the geophysical geodesy are based on the famous explicit expression of Stokes (1849). Up to now,
there has been no method for a computation of the corresponding explicit expression of a (non-spherical) surface with masses
outside the geoid. In this paper there is a solution of this problem. Another paper on this subject was presented to “Nordiska
geodetm?tet” in Copenhagen May 1959 (in Swedish). 相似文献
96.
Brian A. Sturt Arne Dalland John L. Mitchell 《International Journal of Earth Sciences》1979,68(2):523-542
Results are given of a programme of K-Ar age determinations from an equatorial weathering profile beneath the Mid-Jurassic unconformitiy of Anøya, northern Norway. A model is presented where the original age of weathering is considered as Lower Carboniferous with partial resetting of ages during subsequent diagenesis. It is concluded that the Kaolinite of the weathering profile became a closed system of40Ar diffusion in late Triassic times, and that a sufficient thickness of Mesozoic-Tertiary strata was never developed to occasion the resetting of the ages. The implication of the results is that a former thick cover of Upper Palaezoic age formerly existed in the region which was effectively removed by erosion in late Triassic — early Jurassic times. The results of the study are reviewed in a context of North Atlantic palaeogeographical evolution.
Zusammenfassung Aus einem fossilen Bodenprofil unterhalb der mitteljurassischen Diskordanz in Nordnorwegen wurden K-Ar-Alter bestimmt, die auf eine Verwitterung während des Unterkarbons hinweisen. Während der folgenden Diagenese sind die Alter teilweise neu eingestellt worden. Dabei zeigt sich, daß der Kaolinite des ursprünglichen Bodenprofils erst ab Obertrias einem für Ar40-Diffusion geschlossenen System angehört. Es folgt weiter, daß während des Mesozoikums und Tertiärs keine größere Sedimentbedeckung mehr über diesen Profilen möglich war, wohingegen eine erhebliche Mächtigkeit von jungpaläozoischen Sedimenten ehedem vorlag, die während der Obertrias abgetragen wurde. Diese Beobachtungen können mit der paläogeographischen Entwicklung des Nord-Atlantik in Zusammenhang gebracht werden.
Résumé On a déterminé les âges K-Ar, donnés par un sol d'alteration formé pendant le Carbonifère inférieur et sous-jacent à la discordance du jurassique moyen, au nord de la Norvège. Les âges ont été en partie de nouveau déterminés, lors des diagénèses suivantes. Il en ressort que la Kaolinite du profil du sol originel n'appartient à un système fermé de diffusion Ar40 qu'à partir du Trias supérieur. Il s'ensuit qu'un recouvrement sédimentaire épais n'a pu se déposer sur ce profil au cours du Secondaire et du Tertiaire, tandis qu'une épaisseur considérable de sédiments du Paléozoique supérieur existait, enlevès ensuite par érosion au Trias supérieur. Ces observations peuvent être mises en rapport avec le développement paléogéographique de l'Atlantique-Nord.
- , , . . , 40, , . , . .相似文献
97.
At a temperature of 23.0~24.8℃,the mixed feeding of Japanese anchovy larvae was initiated 24 h before the yolk-sac was exhausted.The point of no return(PNR) was reached on the 6th day after hatching.On the 4th day after hatching,the pectoral angle appeared in both fed and unfed anchovy larvae although it was more evident and sharper in the starved and the PNR stage larvae than in the fed ones.According to observations of larvae collected in the sea,the pectoral angles were evident not only in the larvae of 3.62~7.44 mm in standard length,but also in the larvae of 2.70 mm in standard length with remnants of yolk.The pectoral angles became diffuse when the larvae reached 7.84 mm and vanished at 9.86 mm.The pectoral angle cannot be used as a criterion to distinguish healthy from starving larvae. 相似文献
98.
The equations of motion of all relevant parameters of Alfvén waves propagating from the sun outwardly into the expanding interplanetary medium are discussed for the case of a quiet, ideal, isotropic, one-fluid solar wind plasma. It is found that the frequency of the wave reamains constant, while the wave vector and the amplitudes depend, in general, on the evolution of the background medium and on the angle between the wave vector and the interplanetary magnetic field. This latter dependence cancels approximately for the evolution of the amplitudes in the case of a pure, overall spiral magnetic field. It is shown that in this case the results of earlier discussions can be derived by less decisive restrictions. 相似文献
99.
The contribution of urban runoff to organic contaminant levels in harbour sediments near two Norwegian cities 总被引:1,自引:0,他引:1
Cornelissen G Pettersen A Nesse E Eek E Helland A Breedveld GD 《Marine pollution bulletin》2008,56(3):565-573
The main aim of the present study was to compare the quality of particle emissions (urban runoff and settling particles in rivers and harbours) to the quality of top-layer bed sediments, for two Norwegian harbours (Oslo and Drammen). A sub-aim was to investigate whether non-industrial urban runoff contributed to the organotin load of sediments, apart from leaching from ship hulls. Time-integrated samples of stormwater runoff were obtained in an innovative manner, by sampling man-holes in the stormwater system. Settling particles were sampled with sediment traps. The study focused on PAHs, PCBs and organotin compounds. Contaminant levels were generally a factor of 2-10 (PAHs) and 3-30 (TBT) lower in emitted riverine and runoff particles than in top-layer bed sediments, except for PCBs in Oslo harbour (only 20-30% lower). Significant levels of tributyltin (TBT; median 140mug/kg) were shown in runoff particles, showing that TBT can also be emitted via urban sources, since the sampled man-holes were not in areas where dry-docking activities take place. Possible land-based TBT sources include long-lasting house paint and use of TBT as PVC stabilizer and timber preservative. Since there are ongoing emissions into the two studied harbour areas, it is concluded that the addition of an actively sorbing capping material such as activated carbon might be the best remediation alternative. 相似文献
100.
On a relativistic geodesy 总被引:3,自引:1,他引:3
Arne Bjerhammar 《Journal of Geodesy》1985,59(3):207-220
Theoretical formulas for relativistic estimation of geopotential differences are given. The relativistic geoid is defined.
A technique for measuring potential differences with high precision clocks (masers or equivalent) is described. The method
can operate over arbitrary terrestrial distances. Two clocks are used. The drift between the clocks is estimated by using
closed loops. The clocks are used in an operational mode during the whole measuring interval. No satellite links are necessary
but VLBI, GPS and ANIK-links can be used in combination with the method. 相似文献