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241.
Julio Iglesias de Ussel Antonio Trinidad Diego RuIz Eduardo Battaner Antonio J. Delgado José M. Rodriguez-Espinosa Eduard Salvador-Solé José M. Torrelles 《Astrophysics and Space Science》1997,257(2):237-248
In this paper the main findings are presented of a recent study made by a team of sociologists from the University of Granada
on the professional astronomers currently working in Spain. Despite the peculiarities of this group – its youth, twentyfold
increase in size over the last 20 years, and extremely high rate of specialization abroad – in comparison with other Spanish
professionals, this is the first time that the sociological characteristics of the group have been studied discretely. The
most significant results of the study are presented in the following sections. Section 1 gives a brief historical background
of the development of Astronomy in Spain. Section 2 analyzes the socio-demographic profile of Spanish Astronomy professionals
(sex, age, marital status, etc.). Sections 3–5 are devoted to the college education and study programs followed by Spanish
astronomers, focusing on the features and evaluations of the training received, and pre- and postdoctoral study trips made
to research centers abroad. The results for the latter clearly show the importance that Spanish astronomers place on having
experience abroad. Special attention is paid to scientific papers published as a result of joint research projects carried
out with colleagues from centers abroad as a result of these study trips. Section 6 describes the situation of Astronomy professionals
within the Spanish job market, the different positions available and the time taken to find a job after graduation. Section
7 examines Astronomy as a discipline in Spain, including the astronomers' own opinions of the social status of the discipline
within Spanish society. Particular attention is paid to how Spanish astronomers view the status of Astronomy in Spain in comparison
with that of other European countries.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
242.
243.
Eduardo M. García-Roger M. del Mar Sánchez-Montoya Rosa Gómez M. Luisa Suárez M. Rosario Vidal-Abarca Jérôme Latron Maria Rieradevall Narcís Prat 《Aquatic Sciences - Research Across Boundaries》2011,73(4):567-579
In this study we examined the importance of seasonal changes in habitat features and aquatic macroinvertebrate responses in
temporary and perennial streams from two different catchments in the Western Mediterranean region in Spain. Macroinvertebrate
sampling was spatially intensive to account for the relative frequency of meso- (i.e., riffles and pools) and micro-habitats
(i.e., different mineral and organic-based substrata) at each site. Samples were collected at two distinctly different phases
of the hydrograph: (1) during the flowing period, when pool-riffle sequences were well-established, and (2) during the dry
phase, when only isolated pools were expected to occur in the temporary streams. During the dry season, both a reduction in
the available total habitat and in microhabitat diversity in all sites studied was observed. As a result, taxon richness decreased
in all streams, but more dramatically at temporary stream sites and particularly so in the infrequently remaining discontinuous
riffles. Macroinvertebrate assemblages differed among catchments (i.e., geographical identity) and sites (perennial vs. temporary).
Invertebrate differences were also strong within and among meso- and micro-habitats, particularly mineral and organic microhabitat
patches, and differences were due to both loss of taxa from some habitats and some taxa exhibiting certain habitat affinities. 相似文献
244.
Carles Canet Sara I. Franco Rosa María Prol-Ledesma Eduardo González-Partida Ruth Esther Villanueva-Estrada 《Journal of Geochemical Exploration》2011
Boiling can be inferred from fluid inclusion microthermometry studies when a progressive increase in apparent salinity is observed along with a decrease of homogenization temperature (TH) and depth, thus reflecting the partitioning of non-volatile solutes into the liquid phase during steam loss. We propose a model for fluid evolution during boiling based on mass and heat balance equations, which establishes paths in the TH-salinity space that can be compared with fluid inclusion data to confirm or discard boiling. Additionally, the model allows calculating paleo-depths, for which the effect of steam bubbles lowering the hydrostatic pressure is taken into account. 相似文献
245.
Eduardo M. Bretas José V. Lemos Paulo B. Lourenço 《Rock Mechanics and Rock Engineering》2013,46(2):327-339
A numerical model for the hydromechanical analysis of masonry dams based on the discrete element method is presented. The dam and the rock foundation are represented as block assemblies, and a coupled flow-stress analysis is performed in an integrated manner for the entire system. Complex block shapes may be obtained by assembling elementary blocks into macroblocks, allowing the application of the model to situations ranging from equivalent continuum to fully discontinuum analysis. A contact formulation was developed based on an accurate edge–edge approach, incorporating mechanical and hydraulic behavior. The main numerical aspects are described, with an emphasis in the flow analysis explicit algorithm. An application to an existing masonry dam is presented, analyzing its present condition, with excessive seepage, and the proposed rehabilitation intervention. An evaluation of sliding failure mechanisms was also performed, showing the expected improvement in the safety of the structure. 相似文献
246.
AbstractDetrital zircon populations from Carboniferous to Permian sandstones from the Lozar Section of Spiti, northern India, were analyzed with the typology method in order to obtain complementary information on the source areas of the sediments. Zircon grains were subdivided into several groups and subgroups, according to degree of abrasion and morphological features.First appearance of detrital zircons with distinct typologic signature within successive stratigraphic intervals provided useful data about the tectono-magmatic evolution of the northern Indian margin during Late Paleozoic rifting of Gondwana and initial opening of Neotethys. The base of the studied sequence (Lower Carboniferous Thabo Fm.) is characterized by a largely cratonic provenance, seemingly from the Indian Shield to the South. In the Upper Carboniferous Chichong Fm., first occurrence of typical zircons from anatectic granites and increasing abundance of granitoid detritus suggest rapid uplift and unroofing of anatectic rocks of probable Cambro-Ordovician age. In the lowermost Permian (Asselian) glaciomarine Ganmachidam Diamictite, euhedral detrital zircons with peculiar features, associated with Cr-rich chromian spinels and mafic to felsic volcanic rock fragments, hint at emplacement of bimodal alkaline magmatic suites. The same sources, possibly including subvolcanic bodies, continued to be eroded until final break-up, documented by the Permian Kuling Group. 相似文献
247.
Numerical study on the effect of submerged depth on the horizontal plate wave energy converter 总被引:2,自引:0,他引:2
Flávio Medeiros SEIBT ;Eduardo Costa COUTO ;Elizaldo Domingues dos SANTOS ;Liércio André ISOLDI ;Luiz Alberto Oliveira ROCHA 《中国海洋工程》2014,28(5):687-700
The growing search for clean and renewable energy sources has given rise to the studies of exploring sea wave energy. This paper is concerned with the numerical evaluation of the main operational principle of a submerged plate employed for the conversion of wave energy into electrical one. The numerical model used to solve the conservation equations of mass, momentum and transport of volume fraction is based on the finite volume method (FVM). In order to tackle with the flow of mixture of air-water and its interaction with the device, the multiphase model volume of fluid (VOF) is employed. The purpose of this study is the evaluation of a numerical model for improvement of the knowledge about the submerged plate wave energy converter, as well as the investigation of the effect of the distance from the plate to the bottom of the sea (HP) on the performance of the converter. The simulations for several distances of the plate from the seabed show that the optimal efficiency is 64%, which is obtained for HP=0.53 m (88% of the depth). This efficiency is 17% larger than that found in the worst case (HP=0.46 m, 77% of the depth). 相似文献
248.
Mariano J. Albano Paulo da Cunha Lana Claudia Bremec Rodolfo Elías César C. Martins Natalia Venturini Pablo Muniz Silvia Rivero Eduardo A. Vallarino Sandra Obenat 《Marine pollution bulletin》2013
We evaluated benthic habitat quality along a presumed contamination gradient in the Mar del Plata port (Southwestern Atlantic) by coupling biological and chemical proxies in a multidisciplinary approach. Organic matter and photosynthetic pigment contents were higher in silty-clay bottoms of the inner port sites. Levels of all fecal steroids decreased from the inner sites to the port inlet. High concentrations of coprostanol in the inner sites seemed to derive from a permanent population of sea lions rather than from sewage outfalls due to coprostanol/epicoprostanol ratio (IV) values <2.5. PAHs levels were also higher in the inner sector, related to both biomass combustion and petroleum combustion associated to local marine traffic. High disturbance and low ecological status were reflected in low benthic diversity and high AMBI values in the inner sites. 相似文献
249.
Roberto Eduardo Kirchheim Didier Gastmans Hung Kiang Chang Troy E. Gilmore 《水文研究》2019,33(17):2266-2278
The Guarani Aquifer System (GAS) has been studied since the 1970s, a time frame that coincides with the advent of isotopic techniques in Brazil. The GAS isotope data from many studies are organized in different phases: (a) the advent of isotope techniques, (b) consolidation and new applications, (c) isotope assessments and hydrochemistry evolution, and (d) a roadmap to a new conceptual model. The reasons behind the phases, their methodological approaches, and impacts on the regional flow conceptual models are examined. Starting with local δ2H and δ18O assessments of values for water fingerprinting and estimates of recharge palaeoclimate scenarios, studies evolved to more integrated approaches based on multiple tracers. Stable isotope application techniques were consolidated during the 1980s, when new dating approaches dealing with radiogenic and heavy isotopes were introduced. Through the execution of an international transboundary project, the GAS was studied and extensively sampled for isotopes. These results have triggered wider application of isotope techniques, reflecting also world research trends. Presently, hydrochemical evolution models along flow lines from recharge to discharge areas, across large‐scale tectonic features within the entire sedimentary basin, are being combined with residence time estimates at GAS outcrop areas and deep confined units. In a complex system, it is normal that many, and even contradictory hypotheses are proposed, but isotope techniques provide a unique chance to test them. Stable isotope assessments are still needed near recharge areas, and they can be combined with groundwater classical dating procedures, complemented by newer techniques (3H‐3He, CFCs, and SF6). Recent noble gas sampling and world pioneer analytical efforts focused on the confined units in the GAS will certainly led to new findings on the overall GAS circulation. The objective of this article is to discuss how isotope information can contribute to the evolution of conceptual groundwater flow models for regional continental aquifers, such as the GAS. 相似文献
250.
Marco Maffione Fabio Speranza Claudio Faccenna Eduardo Rossello 《Earth and Planetary Science Letters》2010,289(1-2):273-286
The southernmost segment of the Andes of southern Patagonia and Tierra del Fuego forms a ~ 700 km long orogenic re-entrant with an interlimb angle of ~ 90° known as Patagonian orocline. No reliable paleomagnetic evidence has been gathered so far to assess whether this great orogenic bend is a primary arc formed over an articulated paleomargin, or is due to bending of a previously less curved (or rectilinear) chain. Here we report on an extensive paleomagnetic and anisotropy of magnetic susceptibility (AMS) study carried out on 22 sites (298 oriented cores), predominantly sampled in Eocene marine clays from the external Magallanes belt of Tierra del Fuego. Five sites (out of six giving reliable paleomagnetic results) containing magnetite and subordinate iron sulphides yield a positive fold test at the 99% significance level, and document no significant rotation since ~ 50 Ma. Thus, the Patagonian orocline is either a primary bend, or an orocline formed after Cretaceous–earliest Tertiary rotations. Our data imply that the opening of the Drake Passage between South America and Antarctica (probably causing the onset of Antarctica glaciation and global climate cooling), was definitely not related to the formation of the Patagonian orocline, but was likely the sole consequence of the 32 ± 2 Ma Scotia plate spreading. Well-defined magnetic lineations gathered at 18 sites from the Magallanes belt are sub-parallel to (mostly E–W) local fold axes, while they trend randomly at two sites from the Magallanes foreland. Our and previous AMS data consistently show that the Fuegian Andes were characterized by a N–S compression and northward displacing fold–thrust sheets during Eocene–early Miocene times (50–20 Ma), an unexpected kinematics considering coeval South America–Antarctica relative motion. Both paleomagnetic and AMS data suggest no significant influence from the E–W left-lateral Magallanes–Fagnano strike–slip fault system (MFFS), running a few kilometres south of our sampling sites. We thus speculate that strike–slip fault offset in the Fuegian Andes may range in the lower bound values (~ 20 km) among those proposed so far. In any case our data exclude any influence of strike–slip tectonics on the genesis of the great orogenic bend called Patagonian orocline. 相似文献