全文获取类型
收费全文 | 89篇 |
免费 | 4篇 |
国内免费 | 2篇 |
专业分类
大气科学 | 2篇 |
地球物理 | 21篇 |
地质学 | 56篇 |
海洋学 | 8篇 |
天文学 | 3篇 |
综合类 | 1篇 |
自然地理 | 4篇 |
出版年
2021年 | 5篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 1篇 |
2013年 | 2篇 |
2012年 | 3篇 |
2011年 | 2篇 |
2010年 | 6篇 |
2009年 | 3篇 |
2008年 | 7篇 |
2007年 | 4篇 |
2006年 | 4篇 |
2005年 | 5篇 |
2004年 | 9篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1991年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1980年 | 2篇 |
1971年 | 1篇 |
排序方式: 共有95条查询结果,搜索用时 15 毫秒
41.
Kazuo Konagai Yuanbiao Yin Yoshitaka Murono 《Soil Dynamics and Earthquake Engineering》2003,23(3):31-39
Most laterally loaded piles are flexible in the sense that they are not deformed over their entire lengths. Instead, pile deflections become negligible below an ‘active pile length’ La. This La is an important parameter that governs the overall behavior of a rigidly capped pile group. In the present approach, piles closely grouped together beneath a superstructure are viewed as a single equivalent upright beam whose stiffness matrix determines La. This idea is verified for different cases of pile spacing, and is further extended for nonlinear behavior of soils surrounding grouped piles. 相似文献
42.
Dynamic properties of earthquake-induced large-scale rapid landslides within past landslide masses 总被引:5,自引:4,他引:5
During the 2004 Mid-Niigata Prefecture earthquake, thousands of landslides were triggered, among them two large-scale rapid landslides (Higashi Takezawa and Terano landslides) occurred within past landslide masses and dammed the river at the toe of the landslides, posing great risks for the society. Detailed field investigation was performed on these two landslides. To examine the triggering and movement mechanisms, samples were taken from these two landslides. By using a ring shear apparatus, real earthquake wave loading test and cyclic loading tests were performed on these samples. The test results revealed that those sand samples from both landslides can suffer from sliding surface liquefaction phenomenon with very low final apparent friction angles, while the silt sample from Terano landslide showed no liquefaction failure, indicating that the sliding surfaces of these rapid landslides must have been formed within the sand layer in the past landslide masses. 相似文献
43.
P. K. Bhattacharyya Somnath Dasgupta M. Fukuoka Supriya Roy 《Contributions to Mineralogy and Petrology》1984,87(1):65-71
In the metamorphosed manganese oxide ores of India, braunite is ubiquitous in all assemblages from chlorite to sillimanite grades. Chemical analyses of braunite from different prograde assemblages confirm the presence of a fixed R2+ (=Mn2++Mg+Ca) SiO3 molecule in the mineral. Element partitioning between coexisting braunite and bixbyite indicates a near-ideal mixing of Fe+3/ -Mn+3 in the phases. This also indicates that braunite became relatively ferrian while equilibrating with associated phases such as bixbyite, hollandite and jacobsite during prograde reactions. Petrogenetic studies show that as a general trend, prograde lower oxide phases appeared by deoxidation of higher oxide phases. But braunite, a more reduced phase than bixbyite, appeared early from deoxidation of pyrolusite in presence of quartz. Bixbyite could appear later from the reacting pyrolusite-braunite-quartz assemblage. Inferred mineral reaction paths and the general trend of pro-grade deoxidation reactions suggest that the composition of ambient fluid phase was internally buffered during metamorphism. 相似文献
44.
Ivan Borisovich Gratchev Kyoji Sassa Viktor Ivanovich Osipov Hiroshi Fukuoka Gonghui Wang 《Geotechnical and Geological Engineering》2007,25(3):349-367
In this work, the cyclic behavior of bentonite–sand mixtures and factors affecting it were studied by means of a ring-shear
apparatus and a scanning electron microscope. It was found that bentonite content had a significant influence on the liquefaction
potential of the studied soils. A small amount of bentonite in the mixtures would cause the formation of “loose” microstructures,
resulting in the occurrence of rapid liquefaction under cyclic loading, while a high bentonite content would cause the formation
of clay matrixes, thus raising the soil resistance to liquefaction. In addition, the effect of pore water chemistry on the
cyclic behavior of a high plasticity bentonite–sand mixture was carefully examined. It was also found that the presence of
ions in pore water would change the clay microfabric, making it more open and thus more vulnerable to liquefaction. Finally,
the effects of loading frequency on the cyclic behavior of mixtures with different amounts of bentonite were investigated.
It was found that as the bentonite content increased, the influence became more pronounced. 相似文献
45.
Shigeshi Fuchida Jun-ichiro Ishibashi Kazuhiko Shimada Tatsuo Nozaki Masanobu Kawachi Yoshitaka Matsushita Hiroshi Koshikawa 《Geochemical transactions》2018,19(1):15
We observed the initial release rate of metals from four fresh (i.e., without long time exposure to the atmosphere) hydrothermal sulfide cores into artificial seawater. The sulfide samples were collected by seafloor drilling from the Okinawa Trough by D/V Chikyu, powdered under inert gas, and immediately subjected to onboard metal-leaching experiments at different temperatures (5 °C and 20 °C), and under different redox conditions (oxic and anoxic), for 1–30 h. Zinc and Pb were preferentially released from sulfide samples containing various metals (i.e., Mn, Fe, Cu, Zn, Cd, and Pb) into seawater. Under oxic experimental conditions, Zn and Pb dissolution rates from two sulfide samples composed mainly of iron disulfide minerals (pyrite and marcasite) were higher than those from two other sulfide samples with abundant sphalerite, galena, and/or silicate minerals. Scanning electron microscopy confirmed that the high metal-releasing sample contained several galvanic couples of iron disulfide with other sulfide minerals, whereas the low metal-releasing sample contained fewer galvanic couples or were coated by a silicate mineral. The experiments overall confirmed that the galvanic effects with iron disulfide minerals greatly induce the initial release of Zn and Pb from hydrothermal sulfides into seawater, especially under warm oxic conditions. 相似文献
46.
In this paper, we compare the petrological histories of the Kemp Land Coast (east Antarctica), and Gokavaram area (Eastern Ghats), that were supposed to have been juxtaposed. The area around Gokavaram is dominated by different varieties of paragneisses (pelitic, quartzofeldspathic, and calcareous composition) with relatively minor amounts of orthogneisses (mafic, enderbitic, and granitic composition). The rocks were involved in three major phases of deformation, and were finally affected by localised shear movement. On the basis of reaction textures, well preserved in high Mg-Al granulites, and calc-silicate granulites, and geothermobarometric data we deduce a polymetamorphic evolution of the rocks. Following an early M1 metamorphism culminating at 9.2–9.4 kbar, > 950°C, the rocks cooled nearly isobarically down to 850°C. During a subsequent M2 metamorphism, near isothermal decompression to 5–6 kbar occurred. This was followed by near isobaric cooling down to 600–650°C. M3 is a weak amphibolite facies overprint, largely restricted to late shears, which involved hydration as well. Available radiometric data from this area can be interpreted in terms of partial resetting of U-Pb systematics in older sphenes due to M3 metamorphism at ca. 550 Ma. Despite the absence of sufficient isotopic data on the Eastern Ghats granulites, we document a remarkable similarity in the petrological history of the two supposedly erstwhile neighbours. 相似文献
47.
Junichi Takeuchi Naoto Honda Yoshitaka Morikawa Takashi Koike Yutaka Nagata 《Journal of Oceanography》1998,54(1):45-52
Along the southwest coast of the Kii Peninsula, a bifurcation current is regularly observed. By using ADCP data taken on board
the R/V Wakayama of the Wakayama Prefectural Fisheries Experimental Station, characteristics of this bifurcation current are
analyzed. The occurrence frequency of the bifurcation current reaches about 70% in the period from 1988 to 1996. The bifurcation
point appears to be changeable and occurs almost evenly between Cape Ichie and Cape Shionomisaki. The current divergence in
the alongshore direction was also investigated. Positive divergence values dominated in the whole analyzed area, and an onshore
current appears to be dominant along the southwest coast of the Kii Peninsula, except in 1990 when the Kuroshio flowed in
a large meandering path. 相似文献
48.
Gaku Kimura Yujin Kitamura Asuka Yamaguchi Jun Kameda Yoshitaka Hashimoto Mari Hamahashi 《Island Arc》2019,28(5)
The belt boundary thrust within the Cretaceous–Neogene accretionary complex of the Shimanto Belt, southwestern Japan, extends for more than ~ 1 000 km along the Japanese islands. A common understanding of the origin of the thrust is that it is an out of sequence thrust as a result of continuous accretion since the late Cretaceous and there is a kinematic reason for its maintaining a critically tapered wedge. The timing of the accretion gap and thrusting, however, coincides with the collision of the Paleocene–early Eocene Izanagi–Pacific spreading ridges with the trench along the western Pacific margin, which has been recently re‐hypothesized as younger than the previous assumption with respect to the Kula‐Pacific ridge subduction during the late Cretaceous. The ridge subduction hypothesis provides a consistent explanation for the cessation of magmatic activity along the continental margin and the presence of an unconformity in the forearc basin. This is not only the case in southwestern Japan, but also along the more northern Asian margin in Hokkaido, Sakhalin, and Sikhote‐Alin. This Paleocene–early Eocene ridge subduction hypothesis is also consistent with recently acquired tomographic images beneath the Asian continent. The timing of the Izanagi–Pacific ridge subduction along the western Pacific margin allows for a revision of the classic hypothesis of a great reorganization of the Pacific Plate motion between ~ 47 Ma and 42 Ma, illustrated by the bend in the Hawaii–Emperor chain, because of the change in subduction torque balance and the Oligocene–Miocene back arc spreading after the ridge subduction in the western Pacific margin. 相似文献
49.
Miyazawa Yasumasa Kuwano-Yoshida Akira Doi Takeshi Nishikawa Hatsumi Narazaki Tomoko Fukuoka Takuya Sato Katsufumi 《Ocean Dynamics》2019,69(2):267-282
Ocean Dynamics - We demonstrate that assimilation of water temperature measurements by sea turtles into an operational ocean nowcast/forecast system improves representation of mesoscale eddies and... 相似文献
50.
Yoshitaka Komatsu Hiroaki Kato Bo Zhu Tao Wang Fan Yang Randeep Rakwal Yuichi Onda 《山地科学学报》2018,15(4):738-751
Purple soil is highly susceptible for overland flow and surface erosion, therefore understanding surface runoff and soil erosion processes in the purple soil region are important to mitigate flooding and erosion hazards. Slope angle is an important parameter that affects the magnitude of runoff and thus surface erosion in hilly landscapes or bare land area. However, the effect of slope on runoff generation remains unclear in many different soils including Chinese purple soil. The aim of this study was to investigate the relationship between different slope gradients and surface runoff for bare-fallow purple soil, using 5 m × 1.5 m experimental plots under natural rainfall conditions. Four experimental plots(10°, 16°, 20° and 26°) were established in theYanting Agro-ecological Experimental Station of Chinese Academy of Science in central Sichuan Basin. The plot was equipped with water storage tank to monitor water level change. Field monitoring from July 1 to October 31, 2012 observed 42 rainfall events which produced surface runoff from the experimental plots. These water level changes were converted to runoff. The representative eight rainfall events were selected for further analysis, the relationship between slope and runoff coefficient were determined using ANOVA, F-test, and z-score analysis. The results indicated a strong correlation between rainfall and runoff in cumulative amount basis. The mean value of the measured runoff coefficient for four experimental plots was around 0.1. However, no statistically significant relationship was found between slope and runoff coefficient. We reviewed the relationship between slope and runoff in many previous studiesand calculated z-score to compare with our experimental results. The results of z-score analysis indicated that both positive and negative effects of slope on runoff coefficient were obtained, however a moderate gradient(16°-20° in this study) could be a threshold of runoff generation for many different soils including the Chinese purple soil. 相似文献