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91.
A new method of evaluating the rate of mineralization of photoassimilated organic matter is described. This method enables us to compare the rate of direct mineralization of particulate organic carbon (POC) to CO2 with the rate of solubilization of photoassimilated organic carbon followed by the mineralization of the resultant dissolved organic carbon (DOC) under the same conditions. The direct mineralization of photoassimilated carbon from POC to CO2 is a more significant process compared with the mineralization of extracellular released organic carbon. The first-order rate coefficients range from 0.132 to 0.434 day–1 for direct mineralization and 0.034 to 0.189 day–1 for solubilization. 相似文献
92.
Observations of sediment contamination along the coast of Japan were analyzed. When the pollutant concentration is divided by the fine particle fraction in the sediment, a regular pattern is observed in the quantitative relationship among the degree and the area of contamination and the discharge rate of pollutant released continuously into the water along the coast. This regularity was observed with respect to COD,n-hexane soluble substances and heavy metals, and could be expressed by a formula.Polluted particles were supposed to disperse through suspension in the bottom water layer, and thus their distribution in the surface sediment is expected to become similar to effluent dispersion in the surface water. 相似文献
93.
Yayoi Hongo Hajime Obata Dia Sotto Alibo Yoshiyuki Nozaki 《Journal of Oceanography》2006,62(4):441-455
The concentration of dissolved rare earth elements (REE) were determined at 47 stations in the North Pacific surface waters.
Combining with other previous data, we present the surface REE distribution in the North Pacific and discuss the controlling
factors. The surface concentrations increase toward the high latitude and continental margin (e.g. [Nd] > 10 pmol kg−1) from the central North Pacific (e.g. [Nd] < 5 pmol kg−1). The North Pacific Deep Water-normalized REE patterns are varied, indicating that two or more factors contribute to the
REE distribution. We examined four factors making the regional variation of surface REE concentrations mainly; a) particle
scavenging, b) atmospheric dust input, c) vertical mixing and d) lateral transport from the coastal region. Flux calculations
for Nd showed that the influence of atmospheric dust was less significant than the vertical input even in the western upwelling
zone. Moreover, the longitudinal and latitudinal transitions of surface REE seem to reflect the lateral supply from the coastal
areas. We constructed the diagram of surface Er/Lu and Er/Yb molar ratios in order to assess the origin and the input processes
of the surface REE. Both molar ratios showed increasing trend toward PEW (Er/Lu (>10.5) and Er/Yb (>1.4)) from PSUW (Er/Lu
(>7) and Er/Yb (>1.2)). The high Er/Lu and Er/Yb ratios in PEW indicate that the lateral supply of terrestrial materials from
the coastal area is possibly the important factor in PEW, because only weathering and dissolution of rocks can explain such
high Er/Lu and Er/Yb ratios to our knowledge. 相似文献
94.
Hiroshi Murakami Kosei Sasaoka Kohtaro Hosoda Hajime Fukushima Mitsuhiro Toratani Robert Frouin B. Greg Mitchell Mati Kahru Pierre-Yves Deschamps Dennis Clark Stephanie Flora Motoaki Kishino Sei-Ichi Saitoh Ichio Asanuma Akihiko Tanaka Hiroaki Sasaki Katsumi Yokouchi Yoko Kiyomoto Hiroaki Saito Cécile Dupouy Absornsuda Siripong Satsuki Matsumura Joji Ishizaka 《Journal of Oceanography》2006,62(3):373-393
The Global Imager (GLI) aboard the Advanced Earth Observing Satellite-II (ADEOS-II) made global observations from 2 April
2003 to 24 October 2003. In cooperation with several institutes and scientists, we obtained quality controlled match-ups between
GLI products and in-situ data, 116 for chlorophyll-a concentration (CHLA), 249 for normalized water-leaving radiance (nLw) at 443 nm, and 201 for
aerosol optical thickness at 865 nm (Tau_865) and Angstrom exponent between 520 and 865 nm (Angstrom). We evaluated the GLI
ocean color products and investigated the causes of errors using the match-ups. The median absolute percentage differences
(MedPD) between GLI and in-situ data were 14.1–35.7% for nLws at 380–565 nm, 52.5–74.8% nLws at 625–680 nm, 47.6% for Tau_865, 46.2% for Angstrom, and 46.6%
for CHLA, values that are comparable to the ocean-color products of other sensors. We found that some errors in GLI products
are correlated with observational conditions; nLw values were underestimated when nLw at 680 nm was high, CHLA was underestimated
in absorptive aerosol conditions, and Tau_865 was overestimated in sunglint regions. The error correlations indicate that
we need to improve the retrievals of the optical properties of absorptive aerosols and seawater and sea surface reflection
for further applications, including coastal monitoring and the combined use of products from multiple sensors. 相似文献
95.
Benzo(a)pyrene (BP) in the sediment of Osaka Bay were determined. High concentration was found at two stations near the mouth of Shin-Yodo and off Kobe respectively (0.98g g–1 dry mud basis, 1.1g g–1). The concentration decreases regularly from the mouth of the river further into the bay. The other supplemental determination was carried on the sediment and the seawater of Keihin Canal. Notable BP concentration of 89g g–1 was observed in the sediment beneath the effluent outlet of a gasworks. The BP in the sediment near the ironworks was also considerable, while the BP was relatively less in the sediment beneath the effluent outlet of refineries. These data suggest that coke plants working in gasworks or ironworks may be the larger sources of BP than refineries. The results of Osaka Bay coincide with this hypothesis.Cadmium, lead, copper, zinc, nickel, ignition loss and fine sand content were measured from the same sediment samples of Osaka Bay. Cd, Pb, Cu and ignition loss showed the regular distributions which resemble to BP and accordingly, good correlations with BP. No significant correlations were found between BP and Ni, Zn and fine sand content which showed no regular distributions. 相似文献
96.
Masahide Wakita Makio C. Honda Kazuhiko Matsumoto Tetsuichi Fujiki Hajime Kawakami Sayaka Yasunaka Yoshikazu Sasai Chiho Sukigara Mario Uchimiya Minoru Kitamura Toru Kobari Yoshihisa Mino Akira Nagano Shuichi Watanabe Toshiro Saino 《Journal of Oceanography》2016,72(5):665-685
The annual flux of biologically produced organic carbon from surface waters is equivalent to annual net community production (NCP) at a steady state and equals the export of particulate and dissolved organic carbon (POC and DOC, respectively) to the ocean interior. NCP was estimated from carbon budgets of salinity-normalized dissolved inorganic carbon (nDIC) inventories at two time-series stations in the western subarctic (K2) and subtropical (S1) North Pacific Ocean. By using quasi-monthly biogeochemical observations from 2004 to 2013, monthly mean nDIC inventories were integrated from the surface to the annual maximum mixed layer depth and corrected for changes due to net air–sea CO2 exchange, net CaCO3 production, vertical diffusion from the upper thermocline, and horizontal advection. The annual organic carbon flux at K2 (1.49 ± 0.42 mol m?2 year?1) was lower than S1 (2.81 ± 0.53 mol m?2 year?1) (p < 0.001 based on t test). These fluxes consist of three components: vertically exported POC fluxes (K2: 1.43 mol m?2 year?1; S1: 2.49 mol m?2 year?1), vertical diffusive DOC fluxes (K2: 0.03 mol m?2 year?1; S1: 0.25 mol m?2 year?1), and suspended POC fluxes (K2: 0.03 mol m?2 year?1; S1: 0.07 mol m?2 year?1). The estimated POC export flux at K2 was comparable to the sum of the POC flux observed with drifting sediment traps and active carbon flux exported by migrating zooplankton. The export fluxes at both stations were higher than those reported at other time-series sites (ALOHA, the Bermuda Atlantic Time-series Study, and Ocean Station Papa). 相似文献
97.
Makio C. Honda Hajime Kawakami Kazuhiko Matsumoto Masahide Wakita Tetsuichi Fujiki Yoshihisa Mino Chiho Sukigara Toru Kobari Mario Uchimiya Ryo Kaneko Toshiro Saino 《Journal of Oceanography》2016,72(3):373-386
Drifting sediment trap experiments were conducted during various seasons to elucidate the characteristics of particles sinking through the upper 200 m of the water column in the western Pacific at subarctic station K2 and subtropical station S1. The sinking particle flux increased when primary productivity was high at each station, during June–July at K2 and during February at S1. Biogenic opal (Opal) and CaCO3 were the major components of the fluxes at K2 and S1, respectively. Contrary to the expectation of a high flux at the eutrophic station K2 and low flux at the oligotrophic station S1, the annual average organic carbon fluxes at 100 m were comparable at both stations: 62.7 mg C m?2 day?1 at K2 and 56.1 mg C m?2 day?1 at S1. The similarity of the fluxes was perhaps a reflection of the unexpectedly high primary production at S1. At K2, the organic carbon export ratio (organic carbon flux/primary productivity) was significantly and negatively correlated with primary production and tended to decrease with depth. The magnitude of the rate of attenuation of the organic carbon flux with depth was larger at S1 than at K2. This rate of attenuation tended to decrease and increase with primary production at K2 and S1, respectively. The explanation for these patterns may be that the flux of labile organic carbon at relatively shallow depths decreased with increasing primary production at K2, and zooplankton grazing pressure increased with increasing primary productivity at S1. 相似文献
98.
The Models-3 Community Multi-scale Air Quality modeling system (CMAQ) coupled with the Regional Atmospheric Modeling System
(RAMS) is used to simulate three-dimensional concentration distributions of hydroxyl (OH) and hydroperoxyl (HO2) radicals over the western Pacific Ocean during the NASA Transport and Chemical Evolution over the Pacific (TRACE-P) field
campaign. Modeled values of OH and HO2 and their closely related chemical species and photolysis rates are compared with observational data collected onboard the
DC-8 aircraft. Comparison shows that the model reasonably reproduced these observed values over a broad range of conditions
with an overall tendency to overestimate the measured OH and HO2 by a factor of 1.56 and 1.24, respectively. A case study of OH, HO2 and their closely related chemical species and photolysis rates along the DC-8 flights 11 and 12 conducted on 17–18 March
2001 shows that the model reproduces the temporal and spatial variations reasonable well, and produces more reliable OH and
HO2 concentrations in the polluted environment than in the clean marine boundary layer. 相似文献
99.
Evaluation of various satellite sensors for waterline extraction in a coral reef environment: Majuro Atoll, Marshall Islands 总被引:4,自引:0,他引:4
Hiroya Yamano Hiroto Shimazaki Tsuneo Matsunaga Albon Ishoda Caleb McClennen Hiromune Yokoki Kazuhiko Fujita Yoko Osawa Hajime Kayanne 《Geomorphology》2006,82(3-4):398-411
The ability of five satellite sensor bands (IKONOS band 4, Terra ASTER bands 3 and 4, and Landsat ETM+ bands 4 and 5) was examined to extract the waterline at coral reef coasts (Majuro Atoll, Marshall Islands) using different wavelength regions (near infrared [NIR] and shortwave infrared [SWIR]) and different spatial resolutions (4, 15, and 30 m). After performing georeferencing and normalization of the images, density slicing was used to extract the waterline. Comparisons of extracted waterline positions with ground-level data for eight transects and global positioning system (GPS) tracks of the island shorelines showed that NIR bands were superior to SWIR bands because of the characteristics of the coral reef coasts, including a lack of foam and suspended sediments (which can affect the NIR wavelength region, if present) and the presence of remnant water on reef flats during low tide (which can affect the SWIR wavelength region). A linear relationship was found between the estimation errors of waterline positions and the spatial resolutions of the NIR sensors. Analysis on estimation errors and image costs showed that Terra ASTER band 3 was the most cost-effective sensor for extracting waterlines with reasonable accuracy. The results serve as general guidelines for using satellite-derived data to estimate intertidal topography and detect and monitor shorelines in coral reef environments. 相似文献
100.
Atsushi Noda Hajime Katayama Tsumoru Sagayama Kazuya Suga Yasuhito Uchida Kenji Satake Kohei Abe Yukinobu Okamura 《Sedimentary Geology》2007,200(3-4):314-327
A combined approach of field geology and numerical simulation was conducted for evaluating the tsunami impacts on the shelf sediments. The 2003 Tokachi-oki earthquake, M 8.0, that occurred on 25 September 2003 off southeastern Hokkaido, northern Japan, generated a locally destructive tsunami. Maximum run-up height of the tsunami waves reached 4 m above sea level. In order to estimate the tsunami impacts on shallow marine sediments, we compared pre- and post-tsunami marine sediments in water depths of 38–112 m in terms of grain size, sedimentary structure, and microfossil content. Decreases of fine fractions, especially finer than very fine sand, which led to coarsen the mean grain size, were detected in the inner shelf of the northern part of the study area. Foraminiferal assemblages also changed in the coarsened sediments. On the other hand, the other shelf sediments largely unchanged or slightly fined. We also simulated the tsunami wave velocity and direction, and grain size entrained by the modeled tsunami. The numerical simulation resulted in that the 2003 tsunami could transport very fine sand in water depths shallower than 45–95 m at the northern part of the study area. This is comparable with the actual grain-size changes after the tsunami had passed. However, some storms and tidal currents might also be possible to stir the surface sediments after the pre-tsunami survey, so we could not conclude that the grain-size changes had been caused only by the tsunami. Nevertheless, a combined approach of sampling and modeling was powerful for estimating the tsunami impacts under the sea. 相似文献