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排序方式: 共有548条查询结果,搜索用时 15 毫秒
541.
542.
Karina Hjelmervik Nils Melsom Kristensen André Staalstrøm Lars Petter Røed 《Ocean Dynamics》2017,67(7):949-958
To model currents in a fjord accurate tidal forcing is of extreme importance. Due to complex topography with narrow and shallow straits, the tides in the innermost parts of a fjord are both shifted in phase and altered in amplitude compared to the tides in the open water outside the fjord. Commonly, coastal tide information extracted from global or regional models is used on the boundary of the fjord model. Since tides vary over short distances in shallower waters close to the coast, the global and regional tidal forcings are usually too coarse to achieve sufficiently accurate tides in fjords. We present a straightforward method to remedy this problem by simply adjusting the tides to fit the observed tides at the entrance of the fjord. To evaluate the method, we present results from the Oslofjord, Norway. A model for the fjord is first run using raw tidal forcing on its open boundary. By comparing modelled and observed time series of water level at a tidal gauge station close to the open boundary of the model, a factor for the amplitude and a shift in phase are computed. The amplitude factor and the phase shift are then applied to produce adjusted tidal forcing at the open boundary. Next, we rerun the fjord model using the adjusted tidal forcing. The results from the two runs are then compared to independent observations inside the fjord in terms of amplitude and phases of the various tidal components, the total tidal water level, and the depth integrated tidal currents. The results show improvements in the modelled tides in both the outer, and more importantly, the inner parts of the fjord. 相似文献
543.
Asplin Lars Albretsen Jon Johnsen Ingrid Askeland Sandvik Anne Dagrun 《Ocean Dynamics》2020,70(8):1151-1167
Ocean Dynamics - Norway has complicated dynamics in the coastal ocean and in the fjords. In this area is also the largest salmon aquaculture industry in the world. The salmon industry is valuable... 相似文献
544.
A strict formula for geoid-to-quasigeoid separation 总被引:3,自引:2,他引:1
Lars E. Sjöberg 《Journal of Geodesy》2010,84(11):699-702
The paper presented by Flury and Rummel (J Geod 83:829–847, 2009) discusses an important topographic correction to the traditional
formula for the quasigeoid-to-geoid separation. Nevertheless, as their formula is approximate, the reader may ask for its
relation to the strict one (defined as the one consistent with Bruns’s formula and the boundary condition of physical geodesy),
which is now derived. Although the result formally differs from that of Flury and Rummel, we show that the two formulas agree
to the centimetre level all over the Earth. We also discuss the practical computation of the topographic correction. 相似文献
545.
546.
The paper considers the effects of wave age and air stability on the whitecap coverage at sea. This is made by using the logarithmic mean wind velocity profile including a stability function as well as adopting a recent wave age dependent sea surface roughness formula. The results are valid for wind waves in local equilibrium with the steady wind. Examples of results demonstrate clear effects of wave age and air stability on the whitecap coverage. Comparisons are also made with field measurements by Sugihara et al. [Sugihara, Y., et al., 2007. Variation of whitecap coverage with wave-field conditions. J. Mar. Syst. 66, 47–60], representing unstable air stability conditions. Although the data basis is limited, the wave age independent Charnock sea roughness based predictions capture the main features of the observed whitecap coverage, suggesting a stronger dependence on air stability than on wave age in the data. 相似文献
547.
GNSS processing at CODE: status report 总被引:26,自引:19,他引:7
Rolf Dach Elmar Brockmann Stefan Schaer Gerhard Beutler Michael Meindl Lars Prange Heike Bock Adrian Jäggi Luca Ostini 《Journal of Geodesy》2009,83(3-4):353-365
Since May 2003, the Center for Orbit Determination in Europe (CODE), one of the analysis centers of the International GNSS Service, has generated GPS and GLONASS products in a rigorous combined multi-system processing scheme, which promises the best possible consistency of the orbits of both systems. The resulting products, in particular the satellite orbits and clocks, are easily accessible by the user community. In the first part of this article, we focus on the generation of the combined global products at CODE, where we put emphasis not only on accuracy, but also on completeness. We study the impact of GLONASS on the CODE products, and the benefit of using them. Last, but not least, we introduce AGNES (Automated GNSS Network for Switzerland), a regional tracking network of small extensions (roughly 400 km East–West, 200 km North–South), which consequently tracks all GNSS satellites and analyzes their measurements using the CODE products. 相似文献
548.
Michael B.W. Fyhn Lars H. Nielsen Lars O. Boldreel Le D. Thang Jørgen Bojesen-Koefoed Henrik I. Petersen Nguyen T. Huyen Nguyen A. Duc Nguyen T. Dau Anders Mathiesen Ian Reid Dang T. Huong Hoang A. Tuan Le V. Hien Hans P. Nytoft Ioannis Abatzis 《Marine and Petroleum Geology》2009
Seismic stratigraphic and structural analyses of the northwest Phu Khanh Basin, offshore Central Vietnam, based on 2-D seismic data, indicate that the initial rifting began during the latest Cretaceous? or Palaeogene controlled by left-lateral transtension along the East Vietnam Boundary Fault Zone (EVBFZ) and northwest–southeast directed extension east of the EVBFZ. Rifting stopped due to transpression during middle Oligocene times but resumed by left-lateral transtension during the Late Oligocene. Thick sequences of lacustrine and alluvial sediments were deposited during the Palaeogene rift periods. The Late Oligocene rifting ended due to inversion, triggered by right-lateral wrenching near the Palaeogene–Neogene boundary. Following the onset of this inversion regional uplift and volcanism took place in the southern half of the study area and contemporaneous subsidence and transgression took place farther north, leading to widespread carbonate deposition. As the right-lateral wrenching decreased during the early Neogene, thermal subsidence and siliciclastic sedimentation became dominant, resulting in the buildup and southward propagation of the shelf slope. Sediment accumulation and subsidence rates increased after the Middle Miocene times due to eastward tilting of Central Vietnam and the adjacent offshore area. 相似文献