全文获取类型
收费全文 | 313篇 |
免费 | 10篇 |
国内免费 | 7篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 8篇 |
地球物理 | 58篇 |
地质学 | 105篇 |
海洋学 | 49篇 |
天文学 | 95篇 |
综合类 | 3篇 |
自然地理 | 10篇 |
出版年
2022年 | 2篇 |
2021年 | 5篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2017年 | 5篇 |
2016年 | 7篇 |
2015年 | 8篇 |
2014年 | 13篇 |
2013年 | 12篇 |
2012年 | 4篇 |
2011年 | 8篇 |
2010年 | 7篇 |
2009年 | 9篇 |
2008年 | 11篇 |
2007年 | 13篇 |
2006年 | 18篇 |
2005年 | 17篇 |
2004年 | 20篇 |
2003年 | 26篇 |
2002年 | 8篇 |
2001年 | 23篇 |
2000年 | 19篇 |
1999年 | 16篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1972年 | 1篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1966年 | 1篇 |
1965年 | 2篇 |
1964年 | 1篇 |
1963年 | 2篇 |
1962年 | 1篇 |
排序方式: 共有330条查询结果,搜索用时 15 毫秒
101.
Study of the effect of water-soluble fractions of heavy-oil on coastal marine organisms using enclosed ecosystems,mesocosms 总被引:1,自引:0,他引:1
Ohwada K Nishimura M Wada M Nomura H Shibata A Okamoto K Toyoda K Yoshida A Takada H Yamada M 《Marine pollution bulletin》2003,47(1-6):78-84
Mesocosm facilities composed of 4 experimental and 2 reservoir tanks (1.5 m in diameter, 3.0 m in depth and 5 tons in capacity) made of FRP plastics, were constructed in the concrete fish rearing pond in the Fisheries Laboratory, The University of Tokyo. The water-soluble fraction of Rank A heavy residual oil was formed by mixing 500 g of the oil with 10 l of seawater, which was introduced to the 5000 l-capacity tanks. Experimental Run 4 was conducted from May 31 to June 7, 2000. Oil concentrations in the tanks were 4.5 microg/l called LOW, and 13.5 microg/l, called HIGH tank. Bacterial growth rates very quickly accelerated in the HIGH tank just after the loading of oil which corresponded with a high increase of bacterial cells in the same tank after 2 days. Later, bacterial numbers in HIGH tank rapidly decreased, corresponding with the rapid increase of heterotrophic nano-flagellates and virus numbers on the same day. Sediment traps were deployed at the bottom of the experimental tanks, and were periodically retrieved. These samples were observed both under light microscope and epi-fluorescent microscope with UV-excitation. It was observed that the main components of the vertical flux were amorphous suspended matter, mostly originating from dead phytoplankton and living diatoms. It was further observed from the pictures that vertical transport of oil emulsions were probably conducted after adsorption to amorphous suspended matter and living diatoms, and were settling in the sediment traps at the bottom of the tanks. This means that the main force which drives the soluble fraction of oil into bottom sediment would be vertical flux of such amorphous suspended particles and phytoplankton. Further incubation of the samples revealed that the oil emulsions were degraded by the activity of autochtonous bacteria in the sediment in aerobic condition. 相似文献
102.
Effects of deposit feeder Stichopus japonicus on algal bloom and organic matter contents of bottom sediments of the enclosed sea 总被引:4,自引:0,他引:4
Michio K Kengo K Yasunori K Hitoshi M Takayuki Y Hideaki Y Hiroshi S 《Marine pollution bulletin》2003,47(1-6):118-125
Algae growing in an enclosed sea may inhibit eutrophication because they absorb nutrients in the water. However, dead algae often cause anaerobic conditions in the water just above and on sediment after they are deposited on the bottom. We found that Stichopus japonicus inhibited the anaerobic processes coupling water sulfite production in sediment. The present study investigates whether S. japonicus inhibits algal flourish and influences sediment properties such as organic matter contents. Aquarium experiments were carried out at Komatsushima port in Tokushima Prefecture, western Japan. The aquaria used in the experiments were supplied with water directly from the adjacent sea (6 L/min), laid with sand of 10 cm depths, and lighted at 12 h intervals. Six aquaria each containing a sea cucumber from Komatsushima port and six aquaria without any were used in the experiments. Water temperature ranged between 9 and 15 degrees C during December 2000 and April 2001. Salinity ranged between 32 per thousand and 34 per thousand. Algae began to cover the bottom of the aquaria without S. japonicus after 2 weeks, whereas no growth was evident in the aquaria containing sea cucumbers. Chlorophyll a concentration in the surface sediment of the aquaria with S. japonicus (6.1+/-3.6 microg/g, mean S.D.+/-standard deviation) was significantly lower than that without it (60+/-17 microg/g, U-test, p<0.05). Phaeophytin concentration in the surface sediment of the aquaria with S. japonicus (0.9+/-0.09 microg/g) was also significantly lower than that without it (4.5+/-1.0 microg/g, U-test, p<0.05). TOC concentration in the surface sediment of the aquaria with S. japonicus (2.6+/-1.3 microg/g) was slightly lower than that without it (4.0+/-1.2 microg/g). These results showed that algal biomass and organic matter concentration of the bottom were decreased in the presence of S. japonicus. Therefore, S. japonicus inhibits algal bloom and decrease the contents of organic matter deposited on the bottom of enclosed sea areas. 相似文献
103.
104.
We try to find how often, and in what regions large earthquakes (M≥7.0) occur within the shallow portion (20-60 km depth) of a subducting slab. Searching for events in published individual studies and the Harvard University centroid moment tensor catalogue, we find twenty such events in E. Hokkaido, Kyushu-SW, Japan, S. Mariana, Manila, Sumatra, Vanuatu, N. Chile, C. Peru, El Salvador, Mexico, N. Cascadia and Alaska. Slab stresses revealed from the mechanism solutions of these large intraslab events and nearby smaller events are almost always down-dip tensional. Except for E. Hokkaido, Manila, and Sumatra, the upper plate shows horizontal stress gradient in the arc-perpendicular direction. We infer that shear tractions are operating at the base of the upper plate in this direction to produce the observed gradient and compression in the outer fore-arc, balancing the down-dip tensional stress of the slab. This tectonic situation in the subduction zone might be realized as part of the convection system with some conditions, as shown by previous numerical simulations. 相似文献
105.
Aitaro Kato Shingo Yoshida Mitiyasu Ohnaka Hiromine Mochizuki 《Pure and Applied Geophysics》2004,161(9-10):1895-1913
— We have evaluated how the parameters prescribing the slip-dependent constitutive law are affected by temperature and effective normal stress, by conducting the triaxial fracture experiments on Tsukuba-granite samples in seismogenic environments, which correspond to a depth range to 15 km. The normalized critical slip displacement D c almost remains constant below 300oC (insensitive to both temperature and effective normal stress σ n eff); D c increases with increasing temperature above 300 °C, and the rate of D c increase with temperature tends to be largest at higher σ n eff. The breakdown stress drop Δτ b for the granite at constant σ n eff is roughly 80 MPa below 300 °C, and does not depend on σ n eff. Above 300 °C, Δτ b decreases gradually with increasing temperature, and the rate of Δτ b reduction with temperature increases at higher σ n eff. The peak shear strength τ p increases nearly linearly with increasing σ n eff below 300 °C. However, τ p becomes lower above 300 °C, deviating from the linear relation extrapolated from below 300 °C. This is consistent with the onset of crystal plastic deformation mechanisms of Tsukuba granite. 相似文献
106.
107.
Abstract ' In situ basalts' represent the ridge magmatism at and close to the ancient trench-trench-ridge triple junction. Such basalts in the Amami, Mugi, and Setogawa accretionary complexes, Southwest Japan, were described and analysed. The geochemical data show that the ' in situ basalts' include all the types of basalts, ranging from alkali basalts and high-alumina basalts to tholeiites, and the compositions tend towards intermediate and silicic rocks. The data also reveal that the ridge basalts are indistinguishable both from the island arc and intraplate basalts, no affinities with mid-ocean-ridge basalts. The sub-ridge mantle adjacent to the triple junction had a component of sub-arc mantle, and this mantle heterogeneity can be generated by the formation of a slab window. 相似文献
108.
109.
110.