全文获取类型
收费全文 | 100篇 |
免费 | 5篇 |
专业分类
测绘学 | 1篇 |
大气科学 | 7篇 |
地球物理 | 9篇 |
地质学 | 50篇 |
海洋学 | 7篇 |
天文学 | 18篇 |
自然地理 | 13篇 |
出版年
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2016年 | 2篇 |
2015年 | 2篇 |
2014年 | 3篇 |
2013年 | 4篇 |
2011年 | 6篇 |
2010年 | 4篇 |
2009年 | 6篇 |
2008年 | 3篇 |
2007年 | 5篇 |
2006年 | 3篇 |
2005年 | 6篇 |
2004年 | 2篇 |
2003年 | 1篇 |
2002年 | 6篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1981年 | 5篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1969年 | 2篇 |
排序方式: 共有105条查询结果,搜索用时 31 毫秒
1.
Instrument calibration of ocean bottom seismographs 总被引:1,自引:0,他引:1
To increase the accuracy of measuring sea floor motion with ocean bottom seismometers, we calibrate the seismometer system on the ocean floor. Data from the sea floor calibration, augmented with electronic and land calibration data, enables us to find the OBS transfer function to an accuracy of 0.5% in the frequency range of 0.1 to 32 Hz. We are able to distinguish between temperature, instrument and OBS ground coupling effects, all of which alter the transfer function. This paper reviews our method of calibration and discusses the effects of temperature and some of the instrument design features on the vertical seismometer transfer function. 相似文献
2.
Mauffret Alain Leroy Sylvie Vila Jean-Marie Hallot Erwan Mercier de Lépinay Bernard Duncan Robert A. 《Marine Geophysical Researches》2001,22(1):17-45
Using the diving submersible survey NAUTICA we investigated the central part of the Caribbean large igneous province (CLIP) to observe and sample internal portions of this proposed oceanic plateau. Most of the samples are gabbroic and doleritic rocks; basalts are scarce. Radiometric dating by 40Ar/39Ar incremental heating experiments indicate that the intrusive rocks are Campanian in age (81–75 Ma). In some places these intrusive rocks underlie older Santonian (85–83 Ma) extrusive basaltic rocks, suggesting that the Campanian rocks represent a sill injection and an underplating episode. Results of the diving program supplemented by information from ODP and DSDP drilling sites document a 20 m.y. period (94–75 Ma) of igneous activity in the submerged portion of the Caribbean large igneous province (CLIP). In the northern part of the Beata Ridge late Campanian and/or post Campanian uplift is documented by prominent Maastrichtian (71–65 Ma) erosion and the establishment of a Paleocene-middle Eocene (65–49 Ma) carbonate platform. During and after the uplift an extensional period is indicated by seismic images and the subsidence (3 km depth) of the carbonate platform. Paleocene ages (55–56 Ma) determined on some volcanic samples are attributed to localised decompression mantle melting that accompanied the extension. We document a prolonged period of magmatic and tectonic events that do not fit with the current models of short-lived plateau formation during mantle plume initiation but shares many similarities with the constructional histories of other oceanic large igneous provinces. 相似文献
3.
Robert D. Moore Leroy M. Dorman Chin-Yen Huang David L. Berliner 《Marine Geophysical Researches》1981,4(4):451-477
We describe the design and construction of an ocean bottom seismometer configured as a computer, based on an Intersil IM6100 microprocessor plus appropriate peripheral devices. The sensors consist of triaxial 1 Hz seismometers and a hydrophone, each sensor channel being filtered prior to digitizing so that typical noise spectra are whitened. Digital data are recorded serially on magnetic tape. The instrument is placed on the ocean bottom by allowing it to fall freely from just below the surface. An acoustic system allows precise determination of instrument position, acoustic recall, and transmission of operational information to the surface. Release from an expendable anchor is accomplished by redundant pyrotechnic bolts which can be fired by acoustic command or by precision timers.The operational flexibility provided by the micro-computer, which executes the DEC PDP8/E instruction set, enables optimum use of the 6-hr recording capacity (at 128 samples/second/channel) in the context of the particular experiment being performed.
相似文献
相似文献
4.
Segmentation and kinematics of the North America‐Caribbean plate boundary offshore Hispaniola 下载免费PDF全文
Sylvie Leroy Nadine Ellouz‐Zimmermann Jordane Corbeau Frédérique Rolandone Bernard Mercier de Lépinay Bertrand Meyer Roberte Momplaisir José‐Luis Granja Bruña Anne Battani Céline Baurion Evgueni Burov Valérie Clouard Rémy Deschamps Christian Gorini Youri Hamon Manfred Lafosse Jottin Leonel Laetitia Le Pourhiet Pilar Llanes Estrada Nicolas Loget Francis Lucazeau Daniel Pillot Jeffrey Poort Kevin R. Tankoo José‐Luis Cuevas José‐Fernando Alcaide Claude Jean Poix Alfonso Muñoz‐Martin Serge Mitton Yamil Rodriguez Julien Schmitz Leonardo Seeber Andres Carbo‐Gorosabel Santiago Muñoz 《地学学报》2015,27(6):467-478
We explored the submarine portions of the Enriquillo–Plantain Garden Fault zone (EPGFZ) and the Septentrional–Oriente Fault zone (SOFZ) along the Northern Caribbean plate boundary using high‐resolution multibeam echo‐sounding and shallow seismic reflection. The bathymetric data shed light on poorly documented or previously unknown submarine fault zones running over 200 km between Haiti and Jamaica (EPGFZ) and 300 km between the Dominican Republic and Cuba (SOFZ). The primary plate‐boundary structures are a series of strike‐slip fault segments associated with pressure ridges, restraining bends, step overs and dogleg offsets indicating very active tectonics. Several distinct segments 50–100 km long cut across pre‐existing structures inherited from former tectonic regimes or bypass recent morphologies formed under the current strike‐slip regime. Along the most recent trace of the SOFZ, we measured a strike‐slip offset of 16.5 km, which indicates steady activity for the past ~1.8 Ma if its current GPS‐derived motion of 9.8 ± 2 mm a?1 has remained stable during the entire Quaternary. 相似文献
5.
The alluvial architecture of a suspended sediment dominated meandering river: the Río Bermejo,Argentina 下载免费PDF全文
Gregory H. Sambrook Smith James L. Best Jessica Z. Leroy Oscar Orfeo 《Sedimentology》2016,63(5):1187-1208
The alluvial architecture of fine‐grained (silt‐bed) meandering rivers remains poorly understood in comparison to the extensive study given to sand‐bed and gravel‐bed channels. This paucity of knowledge stems, in part, from the difficulty of studying such modern rivers and deriving analogue information from which to inform facies models for ancient sediments. This paper employs a new technique, the parametric echosounder, to quantify the subsurface structure of the Río Bermejo, Argentina, which is a predominantly silt‐bed river with a large suspended sediment load. These results show that the parametric echosounder can provide high‐resolution (decimetre) subsurface imaging from fine‐grained rivers that is equivalent to the more commonly used ground‐penetrating radar that has been shown to work well in coarser‐grained rivers. Analysis of the data reveals that the alluvial architecture of the Río Bermejo is characterized by large‐scale inclined heterolithic stratification generated by point‐bar evolution, and associated large‐scale scour surfaces that result from channel migration. The small‐scale and medium‐scale structure of the sedimentary architecture is generated by vertical accretion deposits, bed sets associated with small bars, dunes and climbing ripples and the cut and fill from small cross‐bar channels. This style of alluvial architecture is very different from other modern fine‐grained rivers reported in the literature that emphasize the presence of oblique accretion. The Río Bermejo differs from these other rivers because it is much more active, with very high rates of bank erosion and channel migration. Modern examples of this type of highly active fine‐grained river have been reported rarely in the literature, although ancient examples are more prevalent and show similarities with the alluvial architecture of the Río Bermejo, which thus represents a useful analogue for their identification and interpretation. Although the full spectrum of the sedimentology of fine‐grained rivers has yet to be revealed, meandering rivers dominated by lateral or oblique accretion probably represent end members of such channels, with the specific style of sedimentation being controlled by grain size and sediment load characteristics. 相似文献
6.
Jacques Leroy 《Mineralium Deposita》1984,19(1):26-35
Résumé Le gisement d'uranium du Bernardan exploité dans le granite à deux micas de la Marche Occidentale appartient au groupe des gisements «d'imprégnation». La minéralisation uranifère (pechblende, coffinite, «produits noirs», autunite, ...) est disseminée dans une roche vacuolaire appelée «épisyénite». Cette dernière résulte d'une altération hydrothermale du granite par des solutions chaudes (370–260°C; 2–5,7% poids équiv. NaCl). Le quartz est dissout; les feldspaths (principalement les plagioclases) et les biotites sont partiellement transformés en phengites. Les muscovites et orthoses granitiques se réequilibrent avec perte de sodium. Cette altération est guidée par un réseau de fractures à différentes échelles. Une altération comparable a été observée dans d'autres gisements du Nord Ouest du Massif Central français, comme Margnac et Fanay dans le massif de St Sylvestre et Hyverneresse dans celui du Millevaches. Les transformations minéralogiques, à l'exception de la quantité de phengites secondaires, les changements chimiques (lessivage de silice et métasomatisme potassique), les conditions P-T et le contrôle tectonique sont les mêmes dans tous ces gisements.
The Bernardan uranium deposit, mined in the Marche Occidentale two-mica granite, is a disseminated type deposit. Similar deposits are known in hercynian belt. Uraniferous mineralizations (pitchblende, coffinite, black minerals, autunite, ...) are disseminated in a vuggy rock called episyenite. It results from an hydrothermal alteration of the granite by hot aqueous solutions (370 to 260°C, 2–5.7 wt% equiv. NaCl). Quartz is dissolved; feldspars (mainly plagioclases) and biotites are partially transformed into phengites. Granitic muscovites and orthoclases are reequilibrated with loss of sodium. This alteration is controlled by fractures at several scales. Such an alteration can be observed in other deposits of the North West part of the French Massif Central, as Margnac and Fanay in the St Sylvestre massif and Hyverneresse in the Millevaches massif. Mineralogical transformations except the content in secondary phengites, chemical changes (SiO2 decrease and potassic metasomatism), P-T conditions and tectonic control are the same in all these deposits.相似文献
7.
Frédéric Gueydan Yves M. Leroy Laurent Jolivet 《International Journal of Earth Sciences》2001,90(1):181-196
Localized shear zones along low-angle normal faults have been identified in regions of extension at the brittle-ductile transition of the continental crust. The possibility of the strain localizing at a depth of 10 km is interpreted here as a consequence of an increase in the equivalent shear stress applied to the flow of the lower crust. This enhancement of the flow stress is seen as a prerequisite for the triggering of brittle deformation mechanisms leading to strain localization. The lower crust rheology used to examine this stress increase is strain-rate, temperature and grain-size dependent, due to the coupling of dislocation and diffusion creep. The model structure proposed consists of a top layer, the upper crust, gliding rigidly above a bottom layer, the lower crust, which deforms in simple shear. During a short time interval (1400 years), the equivalent shear stress is found to increase by a factor of up to 3 (67 MPa for anorthite and 17 MPa for quartz). For anorthite, this stress could explain the activation of a Mohr-Coulomb failure with a friction coefficient of 0.2, which is reasonable at the depth of 10 km. Dislocation creep is activated during a rapid change in the prescribed velocity, whereas diffusion creep dominates if the velocity is held constant, highlighting the importance of grain-size sensitivity for lower crustal rheology. 相似文献
8.
9.
The Bataan orogene: Eastward subduction, tectonic rotations, and volcanism in the western Pacific (Philippines) 总被引:1,自引:0,他引:1
Jelle de Boer Leroy A. Odom Paul C. Ragland Frederic G. Snider Norman R. Tilford 《Tectonophysics》1980,67(3-4)
The Philippine mobile belt represents a crustal fragment, wedged between two subduction systems exhibiting opposite polarity. The eastern (Philippine—Quezon) system probably originated in the Eocene during northwest—southeast spreading of the west Philippine basin. Westward subduction is continued, probably as a result of northward motion of the Philippine basin crust. The western (Manila—Bataan) system originated in the Oligocene by spreading and formation of the South China Sea basin. Eastward subduction dominates the tectonics in the northern part of the archipelago and resulted in the formation of the Bataan orogene, a sequence of three parallel volcanic arcs emplaced in obducted oceanic crust. Geochemical and radiometric data indicate that the arcs migrated eastward with time (Miocene to Present) while changing composition from tholeiitic via calc-alkaline to shoshonitic. Centers of the latter two types are presently active. Depocenters behind the arcs also migrated eastward with time, suggesting correction of the isostatic disequilibrium caused by geanticlinal uplift of the orogene. Paleomagnetic evidence suggests that central Luzon is rotating counterclockwise probably due to differential spreading in the South China Sea basin. The west Philippine basin rotates clockwise. This results in significant “Einengung” in the southern part of the archipelago. 相似文献
10.
Bernard Leroy 《地球物理与天体物理流体动力学》2013,107(2):123-133
Abstract New light is shed on the derivation of the energy flux of the linear MHD waves. It is shown that, according to a suggestion of Lighthill, the usual perturbation procedure, which starts from the general expression for the energy flux, need not be supplemented by an averaging procedure. As a result, it is shown that to second order in the wave amplitude, a quantity identifiable as the wave energy flux is conserved. Some of the subtleties inherent in the derivation of the pertubation energy equation are discussed. 相似文献