全文获取类型
收费全文 | 113篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
大气科学 | 3篇 |
地球物理 | 25篇 |
地质学 | 28篇 |
海洋学 | 33篇 |
天文学 | 19篇 |
综合类 | 1篇 |
自然地理 | 7篇 |
出版年
2019年 | 3篇 |
2018年 | 1篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 2篇 |
2014年 | 5篇 |
2013年 | 3篇 |
2012年 | 4篇 |
2011年 | 2篇 |
2010年 | 8篇 |
2009年 | 7篇 |
2008年 | 14篇 |
2007年 | 8篇 |
2006年 | 3篇 |
2005年 | 3篇 |
2004年 | 5篇 |
2003年 | 4篇 |
2002年 | 1篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1977年 | 1篇 |
排序方式: 共有116条查询结果,搜索用时 15 毫秒
81.
Early arc volcanism during Eocene to Oligocene in the Izu forearc region was investigated during ODP Legs 125 and 126 in 1989,
and effusive and intrusive volcanics were recovered from Leg 125 Site 786. These rocks were all classified into boninites
and associated rocks by Leg 125 Shipboard Scientific Party, and they concluded that boninitic volcanism had occurred before
40 Ma, and arc tholeiitic volcanism began after 40 Ma. In this study, lava flows and breccias that classified into boninite
series are divided into two groups, tholeiite and boninite, based on petrographical and petrological properties. Both series
are also distinguished by bulk rock composition. It is considered that the sources of both rock types have similar depleted
compositions because of their similar, very low bulk HFSE concentrations. We suggest that boninitic and tholeiitic volcanism
occurred closely in time and space, and reflected different temperature and water condition. 相似文献
82.
Equatorial behaviour of a polar-originating ionospheric current is examined by solving numerically the continuity equation on a two-dimensional spherical shell with appropriate assumptions for the ionospheric conductivity and the field-aligned source currents. The results show a clear daytime equatorial enhancement of the ionospheric currents in spite of much reduced electric field due to shielding effects of the enhanced Cowling conductivity there. The results are used for interpretation of the preliminary impulse of the geomagnetic sudden commencement. 相似文献
83.
Satoru Haraguchi Teruaki Ishii Jun-Ichi Kimura 《Contributions to Mineralogy and Petrology》2008,155(5):593-618
Analysis of middle and upper Eocene rocks from the IBM forearc, including the Ogasawara and Mariana Islands, help illuminate
early arc volcanism of the proto-IBM arc. Dredged volcanic rocks from the forearc are two-pyroxene basalt to andesite, and
may be divided into two groups, tholeiite and calc-alkaline, on the basis of mineralogy, petrography, and bulk chemistry.
Tholeiites are characterized by high HFSE contents, high crystallization temperatures, and low water contents. In contrast,
the calc-alkaline rocks are characterized by low HFSE contents, low crystallization temperatures, and higher water contents.
These characteristics indicate that magma genesis for the two series differed. The tholeiites resulted from high degrees of
partial melting of slightly depleted mantle under anhydrous conditions, whereas the calc-alkaline rocks were generated by
low degrees of melting of depleted mantle under hydrous conditions. We believe that differences in mantle depletion arose
from compositional layering and fluid zonations caused by MORB volcanism and slab dehydration, respectively.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
84.
The recent discovery of the large honeycomb structure of the Universe has triggered many models of the Universe dominated by dark matter. The neutrino-dominated universe is a favorable model for explaining the size of the large-scale structure and the dark matter of the larger scale than the galactic one. Our calculations on the evolution of density perturbations in a two-component universe composed of neutrinos and dissipative gas on a spherically-symmetric model have shown that the galactic scale does correlate the scale of a void of galaxies: if a neutrino has the mass of some tens eV, galaxies of the typical size form surrounding a typical void.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984. 相似文献
85.
From the standpoint of view that the early type stars are formed sequentially at an OB association, it is expected that the supernova explosions will also occur sequentially. We study the expansion law of a supernova remnant, which is formed by sequential explosions of supernovae. The superbubbles and supershells with the radii 2001000 pc are naturally explained by this model. Assuming that the sequential explosion of supernovae occurs at every OB association, we deduce the star formation rate in our Galaxy. 相似文献
86.
Satoru Tanaka 《Physics of the Earth and Planetary Interiors》2004,141(3):141-152
I have examined precisely the differential travel times and waveforms of SmKS seismic phases propagating under the southern Indian Ocean obtained from African broadband seismic arrays. The SmKS phases analyzed in this study travel in the mantle with weak heterogeneity confirmed by a global tomographic study for the distance range of 115-135°. The SmKS differential times were obtained from a vespagram (a stack intensity on a time-slowness diagram), and comparison with the vespagram created from synthetic waveforms with PREM gives the travel-time residual for each event-array pair. Although the residuals of S3KS-S2KS times exhibit apparently a systematic dependence on epicentral distance, this is likely due to small-scale heterogeneity beneath the Oceania where is covered by the SmKS ray entering points at the CMB. Waveform modeling was applied to a record section with a small travel-time residual that suggests a small effect from the mantle heterogeneity on the data set, I found that a low-velocity zone in the outermost 50 km in the core rather than PREM can explain an additional arrival detected just after the S3KS phase. This result is still inconclusive because of the small number of data and non-uniqueness of the model and ambiguity due to mantle structure. However, accumulation of the precise measurement described in this study may help the reduction of uncertainty and trade-offs. 相似文献
87.
Yoshimasa Toyota Shiro Okabe Satoru Kanamori Yasushi Kitano 《Journal of Oceanography》1983,38(6):357-361
A simple and rapid coprecipitation method for the determination of several trace metals in seawater is presented. These metals are coprecipitated with lanthanum hydroxide, the precipitate is dissolved, and then the metals are determined by atomic absorption spectrometry. Lanthanum hydroxide was chosen as a coprecipitant for the following reasons, (a) lanthanum hydroxide has a sufficiently low solubility and forms an easily filterable flocculate at about 80C, and (b) lanthanum has an absorption wavelength that is sufficiently separated from those of the other elements to be analysed, i.e., Mn, Fe, Ni, Cu and Zn. Experimental results show that these metals are coprecipitated by the present method with excellent recoveries. 相似文献
88.
When biogenic particles of calcium carbonate and organic matter are formed or decomposed in sea water, calcium concentration, alkalinity and nitrate concentration are changed according to the following equation: ΔCa=0.5 ΔTA+0.63 ΔNO 3, where ΔCa, ΔTA and ΔNO 3 are the differences in calcium, alkalinity and nitrate concentration, respectively, between two waters. This relationship was pointed out in a previous paper of ours, and it holds well for data obtained from the North Pacific and the Japan Sea. Furthermore, in sea water containing little or no nutrients, the variations in calcium concentration and alkalinity are consistent with the variations expected from the formation and dissolution of calcium carbonate alone. 相似文献
89.
Hikaru Iwamori Hitomi Nakamura Masaki Yoshida Takashi Nakagawa Kenta Ueki Atsushi Nakao Tatsuji Nishizawa Satoru Haraguchi 《Comptes Rendus Geoscience》2019,351(2-3):209-220
Recent statistical analyses on the isotopic compositions of oceanic, arc, and continental basalts have revealed that the Earth's mantle is broadly divided into eastern and western hemispheres. The present study aimed to characterize the isotopically defined east–west geochemical hemispheres using trace-element concentrations. Basalt data with Rb, Sr, Nd, Sm, Pb, Th, and U in addition to the isotopic ratios 87Sr/86Sr, 143Nd/144Nd, 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb were selected mostly from the GEOROC and PetDB databases. A total of 4787 samples were used to investigate the global geochemical variations. The results show that the wide trace-element variations are broadly explained by the melting of melt-metasomatized and fluid-metasomatized mantle sources. The larger amount of the fluid component derived from subducted plates in the eastern hemisphere than that in the western hemisphere is inferred from the basalts. These characteristics support the hypothesis that focused subduction towards the supercontinent created the mantle geochemical hemispheres. 相似文献
90.
Does heavy oil pollution induce bacterial diseases in Japanese flounder Paralichthys olivaceus? 总被引:1,自引:1,他引:0
Jun-Young Song Kei Nakayama Yasunori Murakami Sung-Ju Jung Myung-Joo Oh Satoru Matsuoka Hidemasa Kawakami Shin-Ichi Kitamura 《Marine pollution bulletin》2008,57(6-12):889
As basic research for the effect of heavy oil on the fish immune system, in this study, the number of leukocyte was counted in Japanese flounder Paralichthys olivaceus, after exposure to heavy oil at a concentration of 30 g/8 L for 3 days. To compare the numbers of bacteria in the skin mucus between oil-exposed and control fish, viable bacteria were enumerated by counting colony forming unit (CFU). Compared with 5.79 ± 1.88 × 107 leukocytes/mL in the controls, the exposed fish demonstrated higher counts, averaging 1.45 ± 0.45 × 108 cells/mL. The bacterial numbers of control fish were 4.27 ± 3.68 × 104 CFU/g, whereas they were 4.58 ± 1.63 × 105 CFU/g in the exposed fish. The results suggest that immune suppression of the fish occurred due to heavy oil stressor, and bacteria could invade in the mucus, resulting in the increasing leukocyte number to prevent infectious disease. 相似文献