全文获取类型
收费全文 | 4349篇 |
免费 | 770篇 |
国内免费 | 90篇 |
专业分类
测绘学 | 37篇 |
大气科学 | 21篇 |
地球物理 | 4363篇 |
地质学 | 560篇 |
海洋学 | 23篇 |
天文学 | 34篇 |
综合类 | 63篇 |
自然地理 | 108篇 |
出版年
2024年 | 13篇 |
2023年 | 27篇 |
2022年 | 58篇 |
2021年 | 79篇 |
2020年 | 83篇 |
2019年 | 106篇 |
2018年 | 115篇 |
2017年 | 110篇 |
2016年 | 95篇 |
2015年 | 146篇 |
2014年 | 201篇 |
2013年 | 188篇 |
2012年 | 191篇 |
2011年 | 200篇 |
2010年 | 179篇 |
2009年 | 243篇 |
2008年 | 280篇 |
2007年 | 207篇 |
2006年 | 253篇 |
2005年 | 217篇 |
2004年 | 202篇 |
2003年 | 158篇 |
2002年 | 162篇 |
2001年 | 145篇 |
2000年 | 165篇 |
1999年 | 171篇 |
1998年 | 193篇 |
1997年 | 147篇 |
1996年 | 165篇 |
1995年 | 168篇 |
1994年 | 102篇 |
1993年 | 111篇 |
1992年 | 74篇 |
1991年 | 46篇 |
1990年 | 42篇 |
1989年 | 28篇 |
1988年 | 53篇 |
1987年 | 12篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 21篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 5篇 |
1979年 | 12篇 |
1978年 | 6篇 |
1977年 | 10篇 |
1976年 | 1篇 |
1954年 | 6篇 |
排序方式: 共有5209条查询结果,搜索用时 15 毫秒
141.
随着我国机构改革的不断深入和社会主义市场经济体制的逐步建立和完善,地震学会同其他社会团体一样将成为现代社会的支柱之一。以山西省地震学会目前的工作现状为例,指出学会在管理体制、运行机制和活动方式等方面存在的问题,提出了发展思路及建议。 相似文献
142.
143.
144.
0前言中国是一个多地震国家,频繁而严重的地震灾害给人民生命和财产带来了巨大的损失,防震减灾任务任重而道远。回良玉副总理2004年在全国防震减灾工作会议讲话中指出:“防震减灾是全社会共同的责任,要广泛动员社会各方的力量,积极投入到这项事业中来,使防震减灾逐步成为全社会的自觉行动。”因此,总结近40年我国防震减灾工作和改革开放的实践经验,对社会公众进行各种防震减灾宣传教育,广泛动员全社会力量,建立健全防震减灾社会动员机制,增强全社会防震减灾意识,是提高我国综合防震减灾能力,有效地促进地震灾害综合防御各项措施落实的重要途… 相似文献
145.
C. Hsein Juang Haiming Yuan David Kun Li Susan Hui Yang Raymond A. Christopher 《Soil Dynamics and Earthquake Engineering》2005,25(5):403-411
An empirical procedure for estimating the severity of liquefaction-induced ground damage at or near foundations of existing buildings is established. The procedure is based on an examination of 30 case histories from recent earthquakes. The data for these case histories consist of observations of the damage that resulted from liquefaction, and the subsurface soil conditions as revealed by cone penetration tests. These field observations are used to classify these cases into one of three damaging effect categories, ‘no damage’, ‘minor to moderate damage’, and ‘major damage’. The potential for liquefaction-induced ground failure at each site is calculated and expressed as the probability of ground failure. The relationship between the probability of ground failure and the damage class is established, which allows for the evaluation of the severity of liquefaction-induced ground damage at or near foundations. The procedure presented herein represents a significant attempt to address the issue of liquefaction effect. Caution must be exercised, however, when using the proposed model and procedure for estimating liquefaction damage severity, because they are developed based on limited number of case histories. 相似文献
146.
This paper deals with an analysis method for the response and motion of soil-like rigid-plastic bodies under seismic loading conditions. A continuity condition to determine the acceleration distribution within the rigid-plastic body when the failure occurs during seismic motions is proposed. Combining this continuity condition of acceleration and the ‘Generalized Limit Equilibrium Method (GLEM)’, the responses of the earth structure during seismic motions as well as the permanent displacements can be obtained, where GLEM is one of the limit equilibrium methods proposed by the authors for static problems and providing the approximate solution for Kötter's equation. The theoretical formulation of the method, the illustrative examples, and some comparisons between the analytical and experimental results are demonstrated. 相似文献
147.
Introduction The acceleration response spectrum and peak ground acceleration are the necessary and im-portant parameters in earthquake-resistant design at present. They are still active research field. With the increase of digital high accurate strong motion observation data, especially the earth-quakes of Loma Prieta (M=7.0) in 1989; Landers (M=7.3) in 1992; Big Bear (M=6.4) in 1994 and Northridge (M=6.7) in 1994 in USA; Kozani (M=6.6) earthquake and afteshocks in 1995 in Greece; Dinar… 相似文献
148.
The model for the 2000 dike intrusion event between Kozushima and Miyakejima volcano, Japan, was reinvestigated. After the sudden earthquake swarm in Miyakejima volcano, a dike intrusion of large volume was detected by the nationwide GPS network (Geonet). The displacements detected with GPS stations over an area with a radius of about 200 km shows a distribution that is consistent with the dike source being located near Miyakejima volcano.The dike was intruded northwestwards between Miyakejima and the neighboring Kozushima volcano. We searched for the parameters in the models that reproduce the regional displacements due to dike intrusion between Miyakejima and Kozushiima islands. We tested three models, (1) the model with a single dike, (2) the model with a dike and a point dislocation source which represents a creep dislocation source and (3) the model with a dike and a deflation source which represents a magma reservoir. Though all three models can match the horizontal displacements near the source area, model 1 fails to reproduce the regional displacements in the central part of Japan. Both models 2 and 3 can reproduce the regional displacement for horizontal components. Model 3 produces slightly better results than model 2 for vertical components. The balance in the volume budget for models 2 and 3 is also consistent with the observations. These results show that we cannot distinguish between the two models using only GPS observation. As there is no direct evidence for such a large creep or ductile source (corresponds to M7 or more) as proposed in model 2 and the active seismic region migrated back and forth within the linear swarm region, the model with a dike and a deep magma source is preferable. For the deflation point source, we obtained a deflation volume of 1.5 km3 at the depth of 20 km below the dike. An additional ~0.95 km3 of volume loss through caldera collapse and edifice deflation took place at Miyakejima. We conclude that the magma that intruded the dike came in part from below Miyakejima and in part from below the sea floor between Miyakejima and Kozushima, perhaps from reservoirs at the Moho.Editorial responsibility: S Nakada, T Druitt 相似文献
149.
The first sign of magma accumulating beneath Miyakejima, an island volcano in the northern Izu islands, Japan, came at around 18:00 on 26 June 2000, when a swarm of earthquakes was detected by a volcano seismic network on the island. Earthquakes occurred initially beneath the southwest flank near the summit and gradually migrated west of the island, where a submarine eruption occurred the next morning. Earthquakes then migrated further to the northwest between Miyakejima and Kozushima, another volcanic island and developed to the most intense earthquake swarm ever observed in and around Japanese archipelago. To better image how the initial magma intrusion occurred, we relocated hypocenters by using a station-correction method and a double-difference method. The relocated epicenters are generally concentrated near the upper bound of dyke intrusions inferred from geodetic studies throughout the initial stages of the 2000 eruption at Miyakejima from 26 to 27 June 2000. As for seismic activity westward off Miyakejima in the morning on 27 June, hypocenters from both a nationwide seismic network that were relocated by the double-difference method, and those from the volcano seismic network relocated by the station-correction method, formed a very shallow cluster that ascended slowly with time as it propagated northwestward from Miyakejima. This suggests that the dykes have both a radial and upward component of movement.Editorial responsibility: S. Nakada, T. Druitt 相似文献
150.