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101.
Shizuo Tsunogai Shinichiro Noriki Koh Harada Taro Kurosaki Yasunori Watanabe Masaru Maedaa 《Journal of Oceanography》1986,42(2):83-90
Settling particles were collected at 1,460 m and 3,760 m depth in the Antarctic Ocean with sediment traps of time series type. The total deployment period of 40 days was divided into four terms of 10 days each. Seawater samples were collected both at deployment and retrieval of the traps at each site. During the 42 days the concentration of silicate in the surface water decreased by 32%, whereas those of nitrate and phosphate decreased by only 4–5%. The total particulate flux in the Antarctic Ocean is the largest among those hitherto observed in the world ocean. The time variation of the particulate flux at 1,460 m depth almost coincided with that at 3,760 m. The settling particles were comprised roughly of 80% biogenic silica, 15% organic matter and 5% other substances including sea salt. The clay fraction was only 0.05% at 1,460 m depth. The settling flux of biogenic silica agrees fairly well with the calculated rate of change in the concentration of silicate in the surface 100 m. Thus it is concluded that preferential propagation of diatoms reduces the concentration of silicate prior to other nutrients in the Antarctic Ocean. 相似文献
102.
Chlorofluorocarbons (CFC-11 and CFC-12) in the intermediate water having between 26.4 and 27.2 were determined at 75 stations in the western North Pacific north of 20°N and west of 175.5°E in 1993. The intermediate water of 26.4–26.6 was almost saturated with respect to the present atmospheric CFC-11 in the zone between 35 and 45°N around the subarctic front. Furthermore, the ratios of CFC-11/CFC-12 of the water were also of those formed after 1975. These suggest that the upper intermediate water (26.4–26.6) was recently formed by cooling and sinking of the surface water not by mixing with old waters. The water below the isopycnal surface of 26.8 contained less CFCs and the area containing higher CFCs around the subarctic front was greatly reduced. However, the CFC age of the lower intermediate water (26.8–27.2) in the zone around the subarctic front was not old, suggesting that the water was formed by diapycnal mixing of the water ventilated with the atmosphere with old waters not containing appreciable CFCs, probably the Pacific Deep Water. The southward spreading rate decreased with depth and it was one sixth of its eastward spreading rate of the North Pacific Intermediate Water (NPIW). 相似文献
103.
Journal of Oceanography - Copper toxicity inChattonella antiqua (Raphidophyceae) was examined using an artificial seawater medium. The growth rate (Μ) was found to be a unique function of... 相似文献
104.
Shizuo Tsunogai Kentaro Kawada Shuichi Watanabe Takafumi Aramaki 《Journal of Oceanography》2003,59(5):685-693
The distributions of CFC (chlorofluorocarbon) in the water column was determined twice in 2000 and 2001 in the northwestern
Japan Sea. In 2000 the CFC-11 concentration decreased almost exponentially with depth from 6 pmol/kg at a few hundred m deep
to 0.3 pmol/kg or less at the bottom of about 3400 m depth at three stations (40–41°N, 132–133°E) about 300 km off Vladivostok.
In 2001 the CFC-11 concentration increased sharply up to 2 pmol/kg in the bottom water, while it did not increase at a station
(42.0°N, 136.5°E) about 450 km away to the northeast. This is due to the renewal of the bottom water which is replaced by
the surface water flowing down along the continental slope, as suggested by Tsunogai et al. (1999), who proposed the continental shelf pump. Furthermore, an increase in the CFC-11 concentration was observed throughout
the entire water column above 3000 m depth, although the proportion of the increase was about 20%, which was one order of
magnitude smaller than that in the bottom water. The increase in inventory is almost four times larger than that in the bottom
water below 3000 m depth which is equivalent to about 1/6 of the total inventory found in 2000. The increase also means that
3% of the deep water was replaced by the recent surface water, or, if the turnover occurs every year, that the turnover time
of the deep water to be about 30 years.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
105.
Shuichi Watanabe Nobuo Tsurushima Masashi Kusakabe Shizuo Tsunogai 《Journal of Oceanography》1995,51(2):239-255
Methane in the deep water of Izena Cauldron (maximum depth: ca. 1650 m) at the east side of mid-Okinawa Trough was studied by casting a CTD system with 12 Niskin bottles for water sampling at 11 stations inside and outside the cauldron. The water contained much methane up to 706 nmoles/l. The depths of maximum concentration varied widely from station to station, indicating the existence of a considerable number of vents emitting methane and heat. The waters containing less methane formed a straight line in theT-S diagram, while those containing more methane were more largely deviated from the line. The temperature anomaly was virtually proportional to the methane concentration, suggesting that the oxidation rate of methane inside the cauldron is negligibly small and methane can be used as a tracer of the cauldron water. The relation and the estimated vertical diffusivity gave the following fluxes. The emissions of methane and heat out of the bottom below 1450 m turn out to be 1400 moles/day and 7×1010 cal/day, respectively. The total emission rates inside the cauldron are presumed to be about twice the above values. The turnover time of methane has been estimated to be 240 days, which is also that of heat generated from the bottom and probably that of the bottom water. 相似文献
106.
Hajime Kawakami Makio C. Honda Masahide Wakita Shuichi Watanabe 《Journal of Oceanography》2007,63(6):967-982
Time-series measurements of dissolved inorganic carbon (DIC) and nutrient concentrations were conducted in the northwestern
North Pacific from October 2002 to August 2004. Assuming that data obtained in different years represented time-series seasonal
data for a single year, vertical distributions of DIC and nutrients showed large seasonal variabilities in the surface layer
(∼100 m). Seasonal variabilities in normalized DIC (nDIC) and nitrate concentrations at the sea surface were estimated to
be 81–113 μmol kg−1 and 12.7–15.7 μmol kg−1, respectively, in the Western Subarctic Gyre. The variability in nutrients between May and July was generally at least double
that in other seasons. In the Western Subarctic Gyre, estimations based on statistical analyses revealed that seasonal new
production was 39–61 gC m−2 and tended to be higher in the southwestern regions or coastal regions. The seasonal new productions in the northwestern
North Pacific were two or more times higher than in the North Pacific subtropical gyre and the northeastern North Pacific.
It is likely that this difference is due to spatial variations in the concentrations of trace metals and the species of phytoplankton
present. In addition, from estimations of surface pCO2 it was verified that the Western Subarctic Gyre is a source of atmospheric CO2 between February and May and a sink for CO2 between July and October. 相似文献
107.
We found a simple function of pH that relates to sea surface temperature (SST, K) and chlorophyll-a (Chl, µg l−1) using measured surface seawater pH, SST and Chl data sets over the North Pacific: pH (total hydrogen scale at 2°C) = 0.01325 SST − 0.0253 Chl + 4.150 (R2 = 0.95, p < 0.0001, n = 483). Moreover, evaluating the seasonal variation of pH based on this algorithm, we compared the measured pH with the predicted pH at the observational time series stations in subpolar and subtropical regions. The average of ΔpH (measured - predicted, n = 52) was 0.006 ± 0.022 pH. Therefore, the combination of SST and Chl can allow us to determine the spatiotemporal distribution of pH over the North Pacific. Using the climatological data sets of SST and Chl with our pH algorithms, we have described the seasonal distributions of pH at 25°C (pH(25)) and pH in situ temperature (pH(T)) over the North Pacific surface water. 相似文献
108.
Biogeochemistry of Dimethylsulfoniopropionate (DMSP) in the Surface Microlayer and Subsurface Seawater of Funka Bay,Japan 总被引:1,自引:0,他引:1
Twenty-eight sea surface microlayer samples, along with subsurface bulk water samples were collected in Funka Bay, Japan during October 2000–March 2001 and analyzed for dimethylsulfoniopropionate, dissolved (DMSPd) and particulate (DMSPp), and chlorophyll a. The aim of the study was to examine the extent of enrichment of DMSP in the microlayer and its relationship to chlorophyll a, as well as the production rate of dimethylsulfide (DMS) from DMSP and the factors that influence this. The enrichment factor (EF) of DMSPd in the surface microlayer ranged from 0.81 to 4.6 with a mean of 1.85. In contrast, EF of DMSPp in the microlayer varied widely from 0.85–10.5 with an average of 3.21. Chlorophyll a also appeared to be enriched in the microlayer relative to the subsurface water. This may be seen as an important cause of the observed enrichment of DMSP in the microlayer. The concentrations of DMSPp in the surface microlayer showed a strong temporal variation, basically following the change in chlorophyll a levels. Moreover, the microlayer concentrations of DMSPp were, on average, 3-fold higher than the microlayer concentrations of DMSPd and there was a significant correlation between them. Additionally, there was a great variability in the ratios of DMSPp to chlorophyll a over the study period, reflecting seasonal variation in the proportion of DMSP producers in the total phytoplankton assemblage. It is interesting that the production rate of DMS was enhanced in the microlayer and this rate was closely correlated with the microlayer DMSPd concentration. Microlayer enrichment of chlorophyll a and higher DMS production rate in the microlayer provide favorable evidence supporting the view that the sea surface microlayer has a greater biological activity than the underlying water. 相似文献
109.
Zhigang Sun Qinxue Wang Bunkei Matsushita Takehiko Fukushima Zhu Ouyang Masataka Watanabe 《水文科学杂志》2013,58(5):994-1012
Abstract A simple remote sensing evapotranspiration (ET) model (Sim-ReSET) has been proposed but only tested using field measurements at a site with a semi-arid climate. Its performance for mapping ET using only satellite data remained unknown. In this study, the Sim-ReSET model was further evaluated for ET estimation driven by only MODIS data products. The estimated ET rates were compared with ground-based observational data from a variety of ecosystems and climates across China. The results show that MODIS-based ET estimates are consistent with both the ET measurements from eddy covariance flux towers and those from the Penman-Monteith method combined with micrometeorological data. Evaporation fraction (EF) is indicative of land surface moisture. The derivative EF maps demonstrate that the proposed ET data set obtained from the Sim-ReSET model and MODIS data is capable of capturing the spatio-temporal pattern of land surface moisture for different land covers with different climates. Editor Z.W. Kundzewicz Citation Sun, Z.G., Wang, Q.X., Matsushita, B., Fukushima, T., Ouyang, Z., Watanabe, M., and Gebremichael, M., 2013. Further evaluation of the Sim-ReSET model for ET estimation driven by only satellite inputs. Hydrological Sciences Journal, 58 (5), 994–1012. 相似文献
110.
Hiroyuki Yamada Futoshi Nakamura Yasuharu Watanabe Marie Murakami Takeshi Nogami 《水文研究》2008,22(17):3545-3545