全文获取类型
收费全文 | 268篇 |
免费 | 2篇 |
国内免费 | 4篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 8篇 |
地球物理 | 43篇 |
地质学 | 59篇 |
海洋学 | 78篇 |
天文学 | 61篇 |
综合类 | 1篇 |
自然地理 | 22篇 |
出版年
2019年 | 2篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2014年 | 3篇 |
2013年 | 16篇 |
2012年 | 6篇 |
2011年 | 8篇 |
2010年 | 9篇 |
2009年 | 16篇 |
2008年 | 18篇 |
2007年 | 6篇 |
2006年 | 9篇 |
2005年 | 7篇 |
2004年 | 17篇 |
2003年 | 13篇 |
2002年 | 5篇 |
2001年 | 9篇 |
2000年 | 8篇 |
1999年 | 5篇 |
1998年 | 10篇 |
1997年 | 4篇 |
1996年 | 6篇 |
1995年 | 7篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1991年 | 3篇 |
1988年 | 1篇 |
1987年 | 5篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 8篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 2篇 |
1966年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有274条查询结果,搜索用时 31 毫秒
21.
Goh Onitsuka Akihiko Morimoto Tetsutaro Takikawa Atsushi Watanabe Masatoshi Moku Yutaka Yoshikawa Tetsuo Yanagi 《Estuarine, Coastal and Shelf Science》2009,81(3):401-408
The relationship between island-induced cyclonic eddies and chlorophyll a (chl-a) was investigated using field data and satellite images in the eastern channel of the Tsushima Straits. The maximum chl-a concentration around the leeward eddy of the Tsushima Islands was two or three times greater than that of outside the eddy. Two different mechanisms of chl-a enhancement associated with island-induced cyclonic eddies were found in the post-bloom periods. In summer, when nutrients were depleted in the surface layer, eddy pumping increased the nutrient supply in the euphotic zone, resulting in enhanced chl-a around the shallow thermocline near the eddy core. In late autumn, when the mixed layer deepened over the euphotic zone, the mixed layer depth became shallow due to the doming effect of the cyclonic eddy, therefore, the improved irradiance condition led to an increase in the chl-a concentration in the surface mixed layer. Nighttime satellite visible images showed a number of fishing vessels in the lee region of the Tsushima Islands, implying that the enhanced phytoplankton biomass may have resulted in good feeding conditions for fishes and squids in the Tsushima Straits. 相似文献
22.
Luca Bindi Ekaterina A. Sirotkina Andrey V. Bobrov Tetsuo Irifune 《Physics and Chemistry of Minerals》2014,41(7):519-526
The crystal structure and chemical composition of crystals of (Mg1?x Cr x )(Si1?x Cr x )O3 ilmenite (with x = 0.015, 0.023 and 0.038) synthesized in the model system Mg3Cr2Si3O12–Mg4Si4O12 at 18–19 GPa and 1,600 °C have been investigated. Chromium was found as substitute for both Mg at the octahedral X site and Si at the octahedral Y site, according to the reaction Mg2+ + Si4+ = 2Cr3+. Such substitutions cause a shortening of the <X–O> and a lengthening of the <Y–O> distances with respect to the values typically observed for pure MgSiO3 ilmenite and eskolaite Cr2O3. Although no high Cr contents are considered in the pyrolite model, Cr-bearing ilmenite may be the host for chromium in the Earth’s transition zone. The successful synthesis of ilmenite with high Cr contents and its structural characterization are of key importance because the study of its thermodynamic constants combined with the data on phase relations in the lower-mantle systems can help in the understanding of the seismic velocity and density profiles of the transition zone and the constraining composition and mineralogy of pyrolite in this area of the Earth. 相似文献
23.
A molecular face-on view of the Galactic Centre region 总被引:1,自引:0,他引:1
24.
Koshi Nishimura Tatsuhiko Kawamoto Tetsuo Kobayashi Takeshi Sugimoto Shigeru Yamashita 《Bulletin of Volcanology》2005,67(7):648-662
Dacitic magma, a mixture of high-temperature (T) aphyric magma and low-T crystal-rich magma, was erupted during the 1991–1995 Mount Unzen eruptive cycle. Here, the crystallization processes of the low-T magma were examined on the basis of melt inclusion analysis and phase relationships. Variation in water content of the melt inclusions (5.1–7.2 wt% H2O) reflected the degassing history of the low-T magma ascending from deeper levels (250 MPa) to a shallow magma chamber (140 MPa). The ascent rate of the low-T magma decreased markedly towards the emplacement level as crystal content increased. Cooling of magma as well as degassing-induced undercooling drove crystallization. With the decreasing ascent rate, degassing-induced undercooling decreased in importance, and cooling became more instrumental in crystallization, causing local and rapid crystallization along the margin of the magma body. Some crystals contain scores of melt inclusions, whereas there are some crystals without any inclusions. This heterogeneous distribution suggests the variation in the crystallization rate within the magma body; it also suggests that cooling was dominant cause for melt entrapment. Numerical calculations of the cooling magma body suggest that cooling caused rapid crystal growth and enhanced melt entrapment once the magma became a crystal-rich mush with evolved interstitial melt. The rhyolitic composition of melt inclusions is consistent with this model.Editorial responsibility: H Shinohara 相似文献
25.
Propagation of hydromagnetic disturbances in the solar corona and Moreton's wave phenomenon 总被引:2,自引:0,他引:2
Yutaka Uchida 《Solar physics》1968,4(1):30-44
Moreton's wave phenomenon, observed to propagate across the solar disk during certain solar flares, may be explained as the intersection line between an expanding coronal wavefront surface and the chromosphere: The propagation of a hydromagnetic disturbance in a spherically symmetric model corona with a radial magnetic field is studied in the WKB-approximation, and the propagation paths of wavepackets, the shape of the wavefronts expanding in time, and the variation of the direction of material oscillation along the paths are discussed for disturbances in hydromagnetic wave modes. It is shown that the wavefront expanding in fast-mode in the corona has a circular intersection line with the chromosphere, which sweeps on the solar surface with a velocity and a direction of material oscillation just favorable for explaining the observed features of the phenomenon. 相似文献
26.
Tetsuo Hasegawa Masatoshi Ohishi Masaki Morimoto Hiroko Suzuki Norio Kaifu 《Icarus》1984,60(1):211-214
The search for radio spectral lines from Comet Sugano-Saigusa-Fujikawa (1983e) was conducted using the 45-m telescope of Nobeyama Radio Observatory. The frequency ranges of 44.0–46.0 and 47.5–49.5 GHz were surveyed down to , with a beam size of ~35 arc sec. Upper limits have been established for spectral lines of atomic hydrogen, CS, OCS, SO2, H2CO, CH3OH, HCCCCCN, HCOOCH3, CH3OCH3, and CH3CH2CN. The J = 5?4 line from HCCCN in the vibrational ground state possibly has been detected but not confirmed. The suggested total amount of HCCCN in the coma is consistent with the possible picture that HCCCN is the main parent molecule of CN. 相似文献
27.
The atmospheric stable boundary layer (SBL) with a low-level jet is simulated experimentally using a thermally stratified
wind tunnel. The turbulence structure and flow characteristics are investigated by simultaneous measurements of velocity and
temperature fluctuations and by flow visualization. Attention is focused on the effect of strong wind shear due to a low-level
jet on stratified boundary layers with strong stability. Occasional bursting of turbulence in the lower portion of the boundary
layer can be found in the SBL with strong stability. This bursting originates aloft away from the surface and transports fluid
with relatively low velocity and temperature upward and fluid with relatively high velocity and temperature downward. Furthermore,
the relationship between the occurrence of turbulence bursting and the local gradient Richardson number (Ri) is investigated.
The Ri becomes larger than the critical Ri, Ricr = 0.25, in quiescent periods. On the other hand, the Ri number becomes smaller than Ricr during bursting events. 相似文献
28.
29.
Yutaka Nagata Junichi Takeuchi Makoto Uchida Isamu Ishikura Yoshitaka Morikawa Takashi Koike 《Journal of Oceanography》1999,55(3):407-416
The Kuroshio flows very close to Cape Shionomisaki when it takes a straight path. The detailed observations of the Kuroshio were made both on board the R/V Seisui-maru of Mie University and on board the R/V Wakayama of the Wakayama Prefectural Fisheries Experimental Station on June 11–14, 1996. It was confirmed that the current zone of the Kuroshio touches the coast and bottom slope just off Cape Shionomiaki, and that the coastal water to the east of the cape was completely separated from that to the west. The relatively high sea level difference between Kushimoto and Uragami could be caused by this separation of the coastal waters when the Kuroshio takes a straight path. This flow is rather curious, as the geostrophic flow, which has a barotropic nature and touches the bottom, would be constrained to follow bottom contours due to the vorticity conservation law. The reason why the Kuroshio leaves the bottom slope to the east of Cape Shionomisaki is attributed to the high curvature of the bottom contours there: if the current were to follow the contours, the centrifugal term in the equation of motion would become large and comparablee to the Coriolis (or pressure gradient) term, and the geostrophic balance would be destroyed. This creates a current-shadow zone just to the east of the cape. As the reason why the current zone of the Kuroshio intrudes into the coastal region to the west of the cape, it is suggested that the Kii Bifurcation Current off the southwest coast of the Kii Peninsula, which is usually found when the Kuroshio takes the straight path, has the effect of drawing the Kuroshio water into the coastal region. The sea level difference between Kushimoto and Uragami is often used to monitor the flow pattern of the Kuroshio near the Kii Peninsula. It should be noted that Uragami is located in the current shadow zone, while Kushimoto lies in the region where the offshore Kuroshio water intrudes into the coastal region. The resulting large sea level difference indicates that the Kuroshio is flowing along the straight path. 相似文献
30.