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41.
A new technique for detecting colored macro plastic debris on beaches using webcam images and CIELUV 总被引:1,自引:0,他引:1
We have developed a technique for detecting the pixels of colored macro plastic debris (plastic pixels) using photographs taken by a webcam installed on Sodenohama beach, Tobishima Island, Japan. The technique involves generating color references using a uniform color space (CIELUV) to detect plastic pixels and removing misdetected pixels by applying a composite image method. This technique demonstrated superior performance in terms of detecting plastic pixels of various colors compared to the previous method which used the lightness values in the CIELUV color space. We also obtained a 10-month time series of the quantity of plastic debris by combining a projective transformation with this technique. By sequential monitoring of plastic debris quantity using webcams, it is possible to clean up beaches systematically, to clarify the transportation processes of plastic debris in oceans and coastal seas and to estimate accumulation rates on beaches. 相似文献
42.
The role of meso-scale eddies in mixed layer deepening and mode water formation in the western North Pacific 总被引:3,自引:1,他引:2
Shinya Kouketsu Hiroyuki Tomita Eitarou Oka Shigeki Hosoda Taiyo Kobayashi Kanako Sato 《Journal of Oceanography》2012,68(1):63-77
Distributions of mixed layer depths around the centers of anti-cyclonic and cyclonic eddies in the North Pacific Ocean were
composited by using satellite-derived sea surface height anomaly data and Argo profiling float data. The composite distributions
showed that in late winter, deeper mixed layers were more (less) frequently observed inside the cores of the anti-cyclonic
(cyclonic) eddies than outside. This relationship was the clearest in the region of 140°E–160°W and 35°N–40°N, where the temperature
and salinity of the deep mixed layers were similar to those of the lighter variety of central mode water (L-CMW). A simple
one-dimensional bulk mixed layer model showed that both strong sea-surface heat and momentum fluxes and weak preexisting stratification
contributed to formation of the deep mixed layer. These conditions were associated with the anti-cyclonic eddies, suggesting
that these eddies are important in the formation of mode waters, particularly L-CMW. 相似文献
43.
Aya Sakaguchi Masayoshi Yamamoto Junpei Tomita Kenta Mino Keiichi Sasaki Kenji Kashiwaya Takayoshi Kawai 《Quaternary International》2009,205(1-2):65
Uranium and thorium isotopes in an 81-m long sediment core (HDP-04) of Lake Hovsgol, Mongolia, were measured to investigate their downcore distributions and to explore potential linkage to paleoenvironmental changes. Three-dimensional isochron techniques using isotope-ratio diagrams in 238U–234U–230Th–232Th system presented by Ludwig and Titterington were applied to age date the lake sediments at the depths of 11.42, 14.71 and 14.83 m in the HDP-04 section, the estimated ages of these horizons are 66 ± 8, 122 ± 11 and 128 ± 22 ka, respectively. The 238U concentration throughout the entire section fluctuated by a factor of 12, ranging from 19.9 to 232.1 mBq/g with anomalously high 238U peak at 23.8 m in depth, while the 232Th concentration varied only by a factor of about two between 24.3 and 54.0 mBq/g. The discrimination of the bulk 238U into authigenic and terrigenous 238U fractions was attempted, based on the measured 232Th as a correction index for terrigenous materials. In the upper 24 m corresponding to the last 250 ka, the authigenic 238U was higher in interglacials and lower in glacials. This depth profile of authigenic 238U contents was almost identical pattern with that found in a sediment core (VER98-1-6) from the Academician Ridge, Lake Baikal. Further, this profile can be correlated well with that of photosynthetic pigment contents, one of proxies of paleoproductivity, suggesting that the variation of authigenic 238U contents were associated with the environmental change around Lake Hovsgol. 相似文献
44.
A local void and the accelerating Universe 总被引:1,自引:0,他引:1
K. Tomita 《Monthly notices of the Royal Astronomical Society》2001,326(1):287-292
RCW 114 is a filamentary nebula of about 250 arcmin diameter. Based on its large diameter-to-filament-width ratio, the expansion velocity, distance and size of the shell, it has been suggested that RCW 114 is a supernova remnant in its momentum-conserving phase. Confirmation of this identification is important, as the large angular size and extensive optical emission of this object will allow for detailed study to improve our knowledge of supernova remnants and their interaction with the interstellar medium.
We have used the FLAIR instrument on the UK Schmidt Telescope to obtain optical spectra of several filaments in RCW 114. These confirm that the emission is being produced by the interaction of the shock wave of a supernova remnant with the surrounding interstellar medium. We also obtained narrow-band H α +[N ii ] and [S ii ] images to examine the spatial variation in ionization structure. 相似文献
We have used the FLAIR instrument on the UK Schmidt Telescope to obtain optical spectra of several filaments in RCW 114. These confirm that the emission is being produced by the interaction of the shock wave of a supernova remnant with the surrounding interstellar medium. We also obtained narrow-band H α +[N ii ] and [S ii ] images to examine the spatial variation in ionization structure. 相似文献
45.
Koike Katsuaki Yono Oak de Sá Vitor Ribeiro Tomita Shohei Albert Nozaki Tatsuo Takaya Yutaro Komori Shogo 《Mathematical Geosciences》2022,54(7):1183-1206
Mathematical Geosciences - Three-dimensional modeling of geoscientific data of limited amounts and strongly biased locations is difficult and impractical using almost any method. To obtain a... 相似文献
46.
The mechanism of a characteristic sea level response (barotropic coastal ocean response) to wind field fluctuation around
the tip of the Izu Peninsula observed during the middle of December 2000 to the middle of January 2001 was investigated based
on three types of numerical experiments using the Princeton Ocean Model with various parameters. The response was characterized
by the relaxation of sea level falling (rising) during eastward upwelling (westward downwelling) favorable wind regime. Analyses
of quasi-realistic numerical model results in terms of the vertically integrated momentum balances and vorticity balance for
the barotropic mode revealed that: 1) development/abatement of two anomalous circulations generated around the tip of the
Izu Peninsula controls the sea level response through the acceleration/deceleration of a quasi-geostrophic barotropic coastal
current between the circulations; 2) nonlinear vorticity advection by the Kuroshio Current and by the coastal current, coupled
with vorticity diffusion, decelerates the quasi-geostrophic coastal current in the latter half of the wind regimes, which
induces the relaxation of sea level rise/fall. The results of the quasi-realistic numerical experiment suggest that an analysis
of the vorticity balance for the barotropic mode contributes to a better understanding of sea level responses to wind in coastal
regions with strong currents and complex topography. In addition, a numerical experiment with idealized spatially uniform
density stratification and a quasi-realistic wind field shows that if the Kuroshio Current had been shifted far offshore from
the Izu Peninsula during the observation period, westward propagating continental shelf waves would have controlled the coastal
sea level response. 相似文献
47.
Tatsuo Matsuda Kentaro Omura Ryuji Ikeda Takashi Arai Kenta Kobayashi Koji Shimada Hidemi Tanaka Tomoaki Tomita Satoshi Hirano 《Tectonophysics》2004,378(3-4):143
An 1800-m-deep borehole into the Nojima fault zone was drilled at Nojima-Hirabayashi, Japan, after the 1995 Hyogo-ken Nanbu (Kobe) earthquake. Three possible fracture zones were detected at depths of about 1140, 1300, and 1800 m. To assess these fracture zones in this recently active fault, we analyzed the distributions of fault rocks, minerals, and chemical elements in these zones. The central fault plane in the shallowest fracture zone was identified by foliated blue-gray gouge at a depth of 1140 m. The degree of fracturing was evidently greater in the hanging wall than in the footwall. Minerals detected in this zone were quartz, orthoclase, plagioclase, and biotite, as in the parent rock (granodiorite), and also kaolinite, smectite, laumontite, stilbite, calcite, ankerite, and siderite, which are related to hydrothermal alteration. Biotite was absent in both the hanging wall and footwall across the central fault plane, but it was absent over a greater distance from the central fault plane in the hanging wall than in the footwall. Major element compositions across this zone suggested that hydrothermal alteration minerals such as kaolinite and smectite occurred across the central fault plane for a greater distance in the hanging wall than in the footwall. Similarly, H2O+ and CO2 had higher concentrations in the hanging wall than in the footwall. This asymmetrical distribution pattern is probably due to the greater degree of wall–rock fracturing and associated alteration in the hanging wall. We attributed the characteristics of this zone to fault activity and fluid–rock interactions. We analyzed the other fracture zones along this fault in the same way. In the fracture zone at about 1300 m depth, we detected the same kinds of hydrothermal alteration minerals as in the shallower zone, but they were in fewer samples. We detected relatively little H2O+ and CO2, and little evidence for movement of the major chemical elements, indicating little past fluid–rock interaction. In the fracture zone at about 1800 m depth, H2O+ and CO2 were very enriched throughout the interval, as in the fracture zone at about 1140 m depth. However, smectite was absent and chlorite was present, indicating the occurrence of chloritization, which requires a temperature of more than 200 °C. Only smectite can form under the present conditions in these fracture zones. The chloritization probably occurred in the past when the fracture zone was deeper than it is now. These observations suggest that among the three fracture zones, that at about 1140 m depth was the most activated at the time of the 1995 Hyogo-ken Nanbu (Kobe) earthquake. 相似文献
48.
Abstrct The obscuring material distribution of an area of about 2000 square degrees was derived by analyzing about 130 plates, using the starcounts method.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, between 30 September–6 October, 1984. 相似文献
49.