全文获取类型
收费全文 | 366篇 |
免费 | 16篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 5篇 |
大气科学 | 38篇 |
地球物理 | 86篇 |
地质学 | 131篇 |
海洋学 | 35篇 |
天文学 | 65篇 |
自然地理 | 24篇 |
出版年
2021年 | 4篇 |
2020年 | 7篇 |
2019年 | 3篇 |
2018年 | 25篇 |
2017年 | 19篇 |
2016年 | 20篇 |
2015年 | 9篇 |
2014年 | 15篇 |
2013年 | 14篇 |
2012年 | 25篇 |
2011年 | 18篇 |
2010年 | 20篇 |
2009年 | 22篇 |
2008年 | 12篇 |
2007年 | 5篇 |
2006年 | 16篇 |
2005年 | 12篇 |
2004年 | 12篇 |
2003年 | 9篇 |
2002年 | 7篇 |
2001年 | 6篇 |
2000年 | 11篇 |
1999年 | 1篇 |
1998年 | 10篇 |
1997年 | 4篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1984年 | 5篇 |
1983年 | 9篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1959年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有384条查询结果,搜索用时 430 毫秒
171.
Heijn W. van Gent Marc Holland Janos L. Urai Ramon Loosveld 《Journal of Structural Geology》2010,32(9):1375-1391
We present analogue models of the formation of dilatant normal faults and fractures in carbonate fault zones, using cohesive hemihydrate powder (CaSO4·½H2O). The evolution of these dilatant fault zones involves a range of processes such as fragmentation, gravity-driven breccia transport and the formation of dilatant jogs. To allow scaling to natural prototypes, extensive material characterisation was done. This showed that tensile strength and cohesion depend on the state of compaction, whereas the friction angle remains approximately constant. In our models, tensile strength of the hemihydrate increases with depth from 9 to 50 Pa, while cohesion increases from 40 to 250 Pa. We studied homogeneous and layered material sequences, using sand as a relatively weak layer and hemihydrate/graphite mixtures as a slightly stronger layer. Deformation was analyzed by time-lapse photography and Particle Image Velocimetry (PIV) to calculate the evolution of the displacement field. With PIV the initial, predominantly elastic deformation and progressive localization of deformation are observed in detail. We observed near-vertical opening-mode fractures near the surface. With increasing depth, dilational shear faults were dominant, with releasing jogs forming at fault-dip variations. A transition to non-dilatant shear faults was observed near the bottom of the model. In models with mechanical stratigraphy, fault zones are more complex. The inferred stress states and strengths in different parts of the model agree with the observed transitions in the mode of deformation. 相似文献
172.
173.
174.
Ercilla G Córdoba D Gallart J Gràcia E Muñoz JA Somoza L Vázquez JT Vilas F;Prestige Group 《Marine pollution bulletin》2006,53(5-7):208-219
The tanker Prestige sank off NW Iberia on the 19th November 2002. The stern and bow of the Prestige wreck are located on the southwestern edge of the Galicia Bank, at 3565 m and 3830 m water depths, respectively. This bank is a structural high controlled by major faults with predominant N-S, NNE-SSW, and NNW-SEE trends. It is characterized by moderate to low seismic activity. The faults have controlled the local depositional architecture, deforming, fracturing, relocating and distributing sediments since the Valangian (early Cretaceous). The Prestige sinking area corresponds to an asymmetric half-graben structure with a N-S trend, which conditions the present-day morphology. The faulted flank outcrops and its activity and erosion have favoured the occurrence of mass-movements (slumps, slump debris, mass-flows and turbidity currents), building valleys and depositional lobes. Nearsurface sediments comprise mostly terrigenous and biogenous turbiditic muds and sands with a minor presence of hemipelagic muds, except on the fault scarp where pelagites predominate. Potential geological hazards resulting from tectonic and sedimentary processes affect almost the entire Prestige sinking area. 相似文献
175.
Neus Garcias-Bonet Timothy D. Sherman Carlos M. Duarte Núria Marbà 《Estuaries and Coasts》2011,34(6):1161-1168
The presence of the pathogenic protist Labyrinthula sp., the causative agent of seagrass wasting disease and mass mortality events, was assessed in 18 seagrass meadows in the
Balearic region (western Mediterranean). This protist was found in 70% of seagrass meadows investigated and in all seagrass
species present in the region (i.e., Posidonia oceanica, Cymodocea nodosa, and Zostera noltii). Labyrinthula spp. cultures isolated from seven P. oceanica and one Thalassia testudinum meadows were used as inocula to perform cross-infection experiments in order to test seagrass vulnerability to Labyrinthula spp. infection. These isolates produced lesions on P. oceanica and other seagrass species (Zostera marina, Z. noltii, and C. nodosa). P. oceanica and Z. noltii, both species autochthonous to the Mediterranean Sea, were the seagrasses most vulnerable to infection by the tested isolates.
One of the P. oceanica isolates of Labyrinthula sp. also infected the Atlantic seagrass Z. marina, and all of the Mediterranean seagrasses were infected by Labyrinthula sp. isolated from the T. testudinum, native to the Caribbean and Gulf of Mexico. This work confirms that Labyrinthula sp. is commonly found on seagrasses of the Mediterranean Sea and demonstrates that Labyrinthula sp. can infect seagrasses in different genera, in contrast to previous studies where Labyrinthula sp. was considered to be genus-specific. This finding points out the broadly pathogenic nature of some Labyrinthula sp. isolates. Finally, this work identifies Labyrinthula sp. as a possible detrimental agent for P. oceanica. 相似文献
176.
Martin Connors Christian Veillet Ramon Brasser Paul Wiegert Paul Chodas Seppo Mikkola Kimmo Innanen 《Meteoritics & planetary science》2004,39(8):1251-1255
Abstract— The newly discovered asteroid 2003 YN107 is currently a quasi‐satellite of the Earth, making a satellite‐like orbit of high inclination with apparent period of one year. The term quasi‐satellite is used since these large orbits are not completely closed, but rather perturbed portions of the asteroid's orbit around the Sun. Due to its extremely Earth‐like orbit, this asteroid is influenced by Earth's gravity to remain within 0.1 AU of the Earth for approximately 10 years (1997 to 2006). Prior to this, it had been on a horseshoe orbit closely following Earth's orbit for several hundred years. It will re‐enter such an orbit, and make one final libration of 123 years, after which it will have a close interaction with the Earth and transition to a circulating orbit. Chaotic effects limit our ability to determine the origin or fate of this object. 相似文献
177.
Ester Falgàs Juanjo Ledo Beatriz Benjumea Pilar Queralt Alex Marcuello Teresa Teixidó Anna Martí 《Surveys in Geophysics》2011,32(6):857-873
Groundwater management needs detailed aquifer characterization, especially in semiarid costal aquifer systems that are under
hydrological pressure. Our study area is in the Tordera delta, northeastern coast of Spain, where a detrital fluvio-deltaic
aquifer system has been developed above granitic basement. The main purpose of this study is to characterize the complex lithological
structure and the seawater intrusion state by combining hydrological information, audiomagnetotelluric (AMT) and seismic reflection
and refraction models. This allowed us to provide spatially continuous information about aquifer properties and processes.
Thus, we have determined the thickness and continuity of the aquifer units, as well as the morphology and depth to the basement.
The models revealed that the main seawater intrusion main path is found in the western deltaic area that coincides with an
existing buried paleochannel. This new result explains the anomalously high chlorine concentrations observed in the deep semiconfined
aquifer more than 1,500 m inland. 相似文献
178.
By means of new photoelectric observations made in 1974 an attempt to determine the poles of asteroids 9 and 44 was made. Following a method based upon the magnitude-aspect and amplitude-aspect relations, the coordinates of the poles for 9 and 44 were found to be, respectively, λ0 = 191° ± 5°, β0 = 56° ± 6° and λ0 = 100° ± 10°, β0 = 50° ± 10°. The previously published pole for asteroid 22, λ0 = 215° ± 10°, β0 = 45° ± 15°, was confirmed. From its phase relation we determined the phase coefficient of 44 Nysa, a very high albedo object (pv = 0.377). The very low phase coefficient obtained (βv = 0.018 mag/deg) agrees very well with an inverse relation between geometrical albedo and phase coefficient. The results are summarized in a table. 相似文献
179.
180.