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81.
The trend towards global warming and the rapid decline in the extent of summer Arctic sea ice over recent years has increased the feasibility of international Arctic shipping. In this study we propose a seasonal NSR (North Sea Route)/SCR (Suez Canal Route)-combined shipping service linking Shanghai and Rotterdam, using the Northern Sea Route during the economical navigable window but using the traditional Suez Canal Route at other times. Different from the previous literatures, this paper dynamically considers the sea ice extent in the model, which is more reasonable for the assessment of Arctic container shipping, because fuel consumption is highly related to ship speed, while ship speed is determined by the relative distances of ice-covered and ice-free route stages. A new approach is developed to predict the time points at which the ship enters and exits the ice-covered stage, given that both the ship position and the extent of sea ice are constantly changing. The results show that the NSR/SCR-combined Arctic container service can be more economical than the SCR, given lower NSR tariffs. 相似文献
82.
83.
Hydrodynamic processes control many geochemical and ecological processes in the sea. In this paper, the influence of up- and downwelling and entrainment on the ecosystem components are studied. The ecohydrodynamic model was initially used to simulate the whole Baltic Sea to get the boundary conditions for the Gulf of Riga. Then, to study the influence of different hydrodynamic conditions on the algal bloom, three simulations were made for the Gulf of Riga using different boundary and entrainment conditions. It appears that upwelling in the gulf was strongly dependent on open boundary conditions between the Baltic Proper and the gulf. The vertical transport in the Gulf of Riga was many times more intensive in the calculation system Baltic Proper and Gulf of Riga, than in the case where only the Gulf of Riga was simulated. The blue–green algal bloom was influenced by the vertical transport due to different nutrients' limitation mechanism. 相似文献
84.
The biogeochemistry of the sulfur cycle in a ca. 5-m-long sediment core from the eastern slope (221 m water depth) of the Landsort Deep in the west-central Baltic Sea was investigated by analyzing the solid phase records of sulfur isotopes and pyrite textures, besides selected main and minor elements. The sediments were deposited during post-glacial history of the Baltic Sea when the basin experienced alteration of brackish (Yoldia Sea, Littorina Sea) and freshwater (Baltic Ice Lake, Ancylus Lake) conditions. The stable isotopic composition of total sulfur was analyzed as a function of depth. In selected samples pyrite (FeS2), greigite (Fe3S4), and barite (BaSO4) fractions were separated for isotope analyses. Pyrite textures were analyzed by SEM and optical microscopy.Microbial reactions associated with the oxidation of organic matter resulted in assemblages of authigenic sulfide minerals which for the post-Ancylus Lake brackish water environment are dominated by pyrite and for freshwater environments by Fe-monosulfides. The sulfur isotopic composition of the brackish water Littorina Sea sediments (δ34S between −40 and −27‰ vs. V-CDT) is believed to be determined by cellular sulfate reduction rates and reactions involving intermediate sulfur species. The availability of reactive iron and decomposable organic matter as well as sedimentation rate and the chemocline position are important variables upon the δ34S values of sulfides in brackish water environment. The syn-depositional abundance of sulfur and organic matter, and transport of dissolved sulfur species vs. rates of microbial reactions determine δ34S in the freshwater sediments. The upper part of the Ancylus Lake sediments is sulfidized by downward diffusing H2S and/or sulfate from overlying brackish water sediments. Minor concretionary barite formation in the freshwater sediments is most likely due to the reaction of pore water sulfate diffusing downward from brackish water sediments with barium desorbed from freshwater sediments. The size distribution of pyrite framboids in the brackish sediments indicates that the formation mainly occurred from anoxic pore waters, although some pyrite formation in an anoxic water column cannot be excluded. 相似文献
85.
A response of the circulation in the Japan/East Sea (JES) to different kinds of wind forcing is studied, with the emphasis on the warm season, using a primitive equation oceanic model. Wind forcing is based on typical patterns obtained from complex empirical orthogonal functions of 1°-gridded NCEP/NCAR 6 h winds for 1998–2005. These patterns are distinguished by a prevailing wind direction. Northwestern wind and strong cyclonic (C) curl prevail in winter, while a variety of patterns occur in the warm season, differing in the wind direction and curl. Three model runs are performed to examine the circulation in response to a prevailing C wind stress curl or an alternating C and anticyclonic (AC) curl or a strong C curl in the warm season. The simulated features are consistent with the observational evidence, in particular with thermal fronts and frequent eddy locations derived from multi-year infrared satellite imagery. The simulated C circulation intensifies and the subarctic region extends southward with the strengthening of a summer C wind stress curl over the JES. Variability of Subarctic Front (SF) in the western JES (between 130°E and 133°E) is strongly affected by summer wind stress curl. Forcing by an AC curl tends to shift SF northward, while SF shifts to the south under the forcing by a C curl, reaching the southern Ulleung Basin in the case of the strong C curl. In the northwestern JES (off Peter the Great Bay, Russia, and North Korea), the SF northwestern branch (NWSF) is simulated. It is a known feature in autumn and early winter and can also occur in the warm season. The simulation results suggest an AC wind stress curl as the forcing of the formation of the NWSF in the warm season. The Siberia Seamount and sharply bending coastline near Peter the Great Bay facilitate partial separation of the Primorye (Liman) Current from the coast. The wind stress curl can be an additional forcing of the Tsushima Warm Current (TWC) branching off the Korea Strait to the East Korea Warm Current (EKWC) and the offshore branch (OB). In the warm season, the simulated TWC bifurcation occurs farther north, the EKWC is strong, and the OB is weak under the forcing of the AC wind stress curl. The EKWC is weak and the OB is strong under the forcing of the strong C wind stress curl. 相似文献
86.
87.
Hydrography, currents and distribution of suspended matter during a dumping experiment in the western Baltic Sea at a site near Warnemünde 总被引:1,自引:1,他引:0
During a dumping experiment on 20/21 June 2001, an extensive data record was collected to understand the dynamical processes in the water column of the investigation area and to validate model results. Weak westerly winds with strongly changing cloud coverage characterized the meteorological situation. During the second day the wind calmed down and moved shortly to easterly directions. The water column was characterized by a strong vertical stratification with discontinuity layers in temperature and salinity in 12 and 16 m. The current regime was dominated by outflow at the water surface and inflow along the German coast, with strong current shearing in the dumping area. The suspended matter clouds could be identified by optical methods and ADCP (Acoustic Doppler Current Profiler) scattering intensity. During the experiment the suspended matter plumes were only visible at the surface up to 1 h after the dumping. The aerial photographs document that the particle clouds at the surface drifted to the west and, after approximately 40 min, they were only weakly visible. The fine material was concentrated in the discontinuity layer leading to substantially higher values of optical parameters and suspended matter concentration than measured in the surface clouds. Due to the vertical current shears the material was transported in the water column in different directions. At the first day the maximum of the suspended matter in the discontinuity layer was in the north-western corner and in the bottom layer in the northeast corner of the dumping area. Strong wind conditions after the dumping led to periodical resuspension processes. 相似文献
88.
Recent observations of hydrography, currents and volume transports in the straits of the East/Japan Sea are reviewed. It is newly found that bottom cold water in the Korea/Tsushima Strait originating from the northern region of the East/Japan Sea appears not only in summer and autumn but also in winter. Intensive observations in the Korea/Tsushima Strait revealed two distinct cores of northeastward currents in the upper layer of the western and eastern channels. Mean volume transport through the Korea/Tsushima Strait is calculated as 2.5 ± 0.5 Sv from four-year direct and indirect measurements. As continuous monitoring has started in the Tsugaru and Soya Straits, understanding of temporal variability of currents and volume transports through the straits is in progress. For the first time, simultaneous time series of volume transports are available in the Korea/Tsushima and Tsugaru Straits during the winter of 1999–2000. Ouflow through the Tsugaru Strait accounts for about 70% of inflow through the Korea/Tsushima Strait for this period. 相似文献
89.
Wave energy assessments in the Black Sea 总被引:1,自引:0,他引:1
Eugen Rusu 《Journal of Marine Science and Technology》2009,14(3):359-372
The present work aims to evaluate the wave energy resources in the Black Sea basin. The study is focused on the western part
of the sea, which is traditionally considered as being more energetic. In order to give a first perspective of the wave climate,
a medium-term wave analysis was carried out using in situ measured data. As a further step, a wave prediction system was implemented
for the Black Sea. This was based on the simulating waves near-shore model, which is used for both wave generation and near-shore
transformation. This methodology has the advantage that a single model covers the full scale of the modelling process. Various
tests were performed considering data measured at three different locations. Special attention was paid to the whitecapping
process, which is still widely considered to be the weak link in deep water wave modelling. Comparisons carried out against
measured data show that the wave prediction system generally provides reliable results, especially in terms of significant
wave heights and mean periods. By increasing the resolution in geographical space, the field distributions of wave energy
were analysed for both high and average wave conditions. The analysis and the wave prediction system developed are a prerequisite
for further investigations extended in time and with increased resolution in the near-shore direction. 相似文献
90.
Irene R. Schloss Christian Nozais Sbastien Mas Bon van Hardenberg Eddy Carmack Jean-ric Tremblay Sonia Brugel Serge Demers 《Journal of Marine Systems》2008,74(3-4):978
The distribution of picophytoplankton (0.2–2 µm) and nanophytoplankton (2–20 µm) in the Beaufort Sea–Mackenzie Shelf and Amundsen Gulf regions during autumn, 2002 is examined relative to their ambient water mass properties (salinity, temperature and nutrients: nitrate + nitrite, phosphate, and silicate) and to the ratio of variable to maximum fluorescence, Fv/Fm. Total phytoplankton and cell abundances (< 20 µm) were mainly correlated with salinity. Significant differences in picophytoplankton cell numbers were found among waters near the mouth of the Mackenzie River, ice melt waters and the underlying halocline water masses of Pacific origin. Picophytoplankton was the most abundant phytoplankton fraction during the autumnal season, probably reflecting low nitrate concentrations (surface waters average ~ 0.65 µM). The ratio Fv/Fm averaged 0.44, indicating that cells were still physiologically active, even though their concentrations were low (max Chl a = 0.9 mg m− 3). No significant differences in Fv/Fm were evident in the different water masses, indicating that rate limiting conditions for photosynthesis and growth were uniform across the whole system, which was in a pre-winter stage, and was probably already experiencing light limitation as a result of shortening day lengths. 相似文献