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91.
Sediment properties, such as water content and density, have been used to estimate the dry and wet weights, as well as the volume of sediment recovered and discharged, during benthic impact experiments conducted in the Pacific and Indian Oceans. The estimates show that the weights of dry (355-1332 t) and wet sediment (1651-4888 t) recovered during the experiments, are not only a function of the total duration and distance covered during the experiment, but also depend on water content and density of the sediment. Estimation of dry sediment and its volumetric ratio in the discharge, are key parameters for calculating the discharged volume. The estimated volume of wet sediment recovered (1427-4049 m 3 ) as well as discharged (2693-6951 m 3 ) during the experiments, provide important inputs to evaluate the sediment resettlement and migration. Using these estimates, the average depth of excavation on the seafloor, can also been calculated. However, the stages of sediment recovery and discharge are expressed differently in some of the experiments. In order to standardize these, different stages have been identified, and definitions of certain terms have been suggested, for use in the future. The methods of calculating different properties, as well as weight and volume of discharged sediment are described in the paper for use in other applications concerning deep-sea discharges. 相似文献
92.
Sea surface temperature (SST) variation around the Nansei Shoto (Okinawa Islands), Japan from March 1998 to February 1999
is investigated using the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) images. Root mean squared (RMS)
error of SST by TMI from the in situ observed SST is 0.9°C. The results of statistical analysis of SST by TMI show that a
14–16 days period variation dominates around the main Okinawa Island, while a 9–11 days period variation dominates along the
shelf edge of the East China Sea.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
93.
The residual currents in Tokyo Bay during four seasons are calculated diagnostically from the observed water temperature, salinity and wind data collected by Unokiet al. (1980). The calculated residual currents, verified by the observed ones, show an obvious seasonal variable character. During spring, a clear anticlockwise circulation develops in the head region of the bay and a strong southwestward current flows in the upper layer along the eastern coast from the central part to the mouth of the bay. During summer, the anticlockwise circulation in the head region is maintained but the southwestward current along the eastern coast becomes weak. During autumn, the preceding anticlockwise circulation disappears but a clockwise circulation develops in the central part of the bay. During winter, the calculated residual current is similar to that during autumn. As a conclusion, the seasonal variation of residual current in Tokyo Bay can be attributed to the variation of the strength of two eddies. The first one is the anticlockwise circulation in the head region of the bay, which develops in spring and summer and disappears in autumn and winter. The second one is the clockwise circulation in the central part of the bay, which develops in autumn and winter, decreases in spring and nearly disappears in summer. 相似文献
94.
Tetsuo Yanagi 《Journal of Oceanography》1980,36(5):246-252
Some current measurements were carried out in Ôsaka Bay to understand the characteristics and causes of fluctuations of the constant flow in the bay. It is shown that the major part of fluctuation of the constant flow in Ôsaka Bay is the wind-driven current. The direction of the wind-driven current in the near surface water deflects clockwise through 10 to 30 degrees from the wind direction while in the lower layer the current deflects counter-clockwise to that in the near surface water in the eastern half of Ôsaka bay. The speed of the wind-driven current in the near surface water is 0.5 to 1.5% of the wind speed while that in the lower layer is smaller than that in the near surface water in this area. 相似文献
95.
Water, Salt, Phosphorus and Nitrogen Budgets of the Japan Sea 总被引:1,自引:0,他引:1
Tetsuo Yanagi 《Journal of Oceanography》2002,58(6):797-804
Water, salt, phosphorus and nitrogen budgets of the Japan Sea have been calculated by box model analysis using historical
data. Average residence time of the Tsushima Warm Current Water in the upper 200 m is 2.1 years and that of the Japan Sea
Proper Water is 90 years. The salt flux from the Tsushima Strait balances those through the Tsugaru and Soya Straits. Average
residence times of phosphorus and nitrogen from the Tsushima Strait are 2.2 years and 1.6 years, respectively, in the upper
200 m of the Japan Sea. Total nitrogen/total phosphorus ratios of riverine load, the Tsushima Warm Current water and the water
in the Japan Sea are 16.4, 16.6 and 11.3, respectively. This suggests that denitrification is dominant in the Japan Sea.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
96.
97.
98.
Kazuo Konagai Shigeki Takatsu Tetsuo Kanai Tomohiro Fujita Takaaki Ikeda Jörgen Johansson 《Soil Dynamics and Earthquake Engineering》2009
Earthquakes in active-folding zones often trigger long-lasting landform changes. Since an underground structure closely follows the motion of its surrounding soils and rocks even after it was damaged in an intense earthquake, experts in charge of reconstruction have to wait until they are convinced that the soils and rocks have been stabilized. Kizawa tunnel was seriously cracked during the 23 October 2004 Mid-Niigata Earthquake. The upper half of the tunnel's cross-section near the north mouth shifted about 0.5 m sideways. Since a ring-shaped cross-section of a tunnel sustains the surrounding soil pressure, this crack pattern seemed to be serious. The authors collaborated with the Nagaoka Regional Development Bureau, Niigata Prefectural Government, in investigating the causes of the damage and in conducting long-term observation of the soils and rocks. This paper summarizes some findings for rational rehabilitations through the investigations. 相似文献
99.
Tetsuo Yanagi 《Journal of Oceanography》1999,55(3):439-448
Seasonal variations in freshwater, salt, phosphorus and nitrogen budgets of Hakata Bay, Japan were investigated from April 1993 until March 1994. The internal sink of dissolved inorganic phosphorus (DIP) and nitrogen (DIN), and the internal source of dissolved organic phosphorus (DOP) and nitrogen (DON) predominate in the bay. This means that the production of organic matter is larger than respiration, and atmospheric CO2 is absorbed in the water column of Hakata Bay. Denitrification is more dominant than nitrogen fixation in the bay. Compared to Tokyo and Mikawa Bays, Hakata Bay is harder to eutrophicate, mainly due to the shorter residence time of freshwater. 相似文献
100.
Characteristics of Sea Surface Circulation and Eddy Field in the South China Sea Revealed by Satellite Altimetric Data 总被引:4,自引:0,他引:4
Temporal and spatial variations of sea surface circulation in the South China Sea were revealed with use of altimetric data provided by TOPEX/POSEIDON from December 1992 to October 1997. The estimated distribution of sea surface dynamic heights from altimetric data coincide well with the results of observation by Soong et al. (1995) and Chu et al. (1998). The RMS variability of sea surface dynamic height, which is obtained after tidal correction based on Yanagi et al. (1997), is high in the central part of the South China Sea, the Gulf of Tongking, the Sunda Shelf and the Gulf of Thailand. The high RMS variability in the Gulf of Tongking, the Sunda Shelf and the Gulf of Thailand is due to set up and set down of sea water by the East Asian monsoon, which is northeasterly during winter and southwesterly during summer. Also, the high RMS variability in the central part of the South China Sea is due to the variations of basin-wide circulation. The circulations are dominant in the central part of the South China Sea during summer and winter, an anticyclonic circulation during summer and a cyclonic circulation during winter. It is suggested that these circulations are controlled by the East Asian monsoon. Hence, there is an interannual variability of the basin-wide circulation associated with the variation of the East Asian monsoon. 相似文献