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141.
R. V. de la Cruz 《Rock Mechanics and Rock Engineering》1978,10(4):221-239
SummaryModified Borehole Jack Method for Elastic Property Determination in Rocks This paper describes a method of determining thein-situ elastic properties of rock masses with friction-strain gauges and a lengthened borehole jack.The method involves impressing tangentially-oriented friction gauges on opposite quadrants of a borehole wall, while the remaining quadrants are loaded by the borehole jack with a unidirectional self-equilibrating pair of forces. The tangential normal strains generated at the borehole wall are thus measured concurrently with the loading. To determine the modulus of the rock mass, equations were developed relating the measured tangential normal strains and the applied ram pressures.Several factors which may influence the interpretation of data were thoroughly analyzed. It was shown that variations in the pressure distribution and area of plate-wall contact have negligible effects on the accuracy of data interpretation. End effects were minimized by lengthening the jack and carrying out strain measurements at the central region only where stresses and strains are homogeneous and plane strain conditions exist.The new method has the same desirable mechanical and operational features as the well-known Goodman-Jack method. Most important, however, its theoretical basis is exact with no estimated coefficients required in the reduction of observed data. While the method requires an ideal elastic material, it has a number of other applications for in-situ measurements besides modulus determination. The modified method could be utilized for determining linearity, anisotropy, inhomogeneity, tensile strength and, with an additional operation, the in-situ stress field.
With 6 Figures 相似文献
ZusammenfassungModifizierte Methode zur Bestimmung der elastischen Kenngröen von Fels mittels einer Bohrlochaufweitungssonde Es wird eine Methode zur Bestimmung der elastischen Kenngrößen von Fels aus In-situ-Versuchen mittels Reibungs-Dehn-meßstreifen und einer verlängerten Bohrlochaufweitungssonde beschrieben.Tangential orientierte Reibungsmeßstreifen werden an gegenüberliegenden Quadranten des Bohrloches angebracht, während die beiden anderen Quadranten mit der Bohrlochaufweitungssonde belastet werden, um Belastung und Verformung gleichzeitig zu messen. Gleichungen wurden entwickelt um daraus den Modul der Steinmasse zu bestimmen.Es wird gezeigt, daß eine ungleichmäßige Verteilung des Druckes und die Platten-Wand-Kontaktfläche einen unbedeuteten Einfluß auf die Exaktheit der Ergebnisse haben. Randeinflüsse wurden verringert, indem Messungen nur in der Mitte der Sonde ausgeführt wurden.Diese neue Methode hat dieselben Vorteile wie die bekannte Goodman-Jack Methode. Am wichtigsten ist aber, daß ihre theoretische Basis exakt ist. Obwohl die Methode nur in einem ideal elastischen Material anwendbar ist, kann sie außer für Modul-Bestimmung auch für andere In-situ-Messungen gebraucht werden, wie z. B. Linearität, Anisotropie, Inhomogenität, Zugfestigkeit und den primären Spannungszustand.
RésuméMéthode modifiée pour déterminer les repères élastiques de rochers par une sonde d'élargissement de trous de sonde Cet article décrit une méthode de mesure des propriétés élastiquesin-situ des masses rocheuses, à l'aide d'indicateurs de déformation à friction, et d'un vérin alongé pour trou de sondage.La méthode consiste à imprimer des indicateurs de déformation à friction sur les quadrants opposés de la paroie d'un trou de sondage, et à charger les deux autre quadrants avec deux forces de même direction qui s'équilibrent, utilisant le vérin pour trou de sondage. Les déformations tangentielles normales créées sur la paroie du trou de sondage sont ainsi mesurées avec la charge correspondante. Afin de pouvoir déterminer le module d'élasticité de la masse rocheuse on a développé les équations qui relient les déformations normales tangentielles mesurées aux pressions appliquées.On a analysé en detail plusieurs facteurs qui pourraient influencer l'interprétation des données. On a montré que des variations dans la distribution de la pression, et dans la surface de contact entre le piston et la paroie, ont un effet négligeable sur la précision de l'interprétation des données. Les effets d'extrémités ont été réduits au minimum en alongeant le piston, et en ne mesurant les déformations que dans la région centrale, où les contraintes et déformations sont homogènes et des conditions de deformation plane existent.La nouvelle méthode a les mêmes caractéristiques mécaniques et opérationnelles désirables que la méthode bien connue Goodman-Jack. Encore plus important est le fait que sa base théorique est exacte, et il n'est pas nécessaire d'utiliser des coefficients estimés pour réduire les résultats observés. Bien que la méthode exige un milieu élastique idéal, elle peut être utilisée pour des mesuresin-situ autres que les mesures du module d'élasticité. La méthode modifiée pourrait être utilisée pour déterminer la linéarité, l'anisotropie, le manque d'homogénéité, la résistance à la traction et, avec une opération supplémentaire, le champ des forcesin-situ.
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142.
A spectral analysis of Iberian Peninsula monthly rainfall 总被引:2,自引:0,他引:2
J. A. García A. Serrano M. de la Cruz Gallego 《Theoretical and Applied Climatology》2002,71(1-2):77-95
Summary A spectral analysis of Iberian Peninsula monthly rainfall series was carried out. The data set consists of monthly precipitation
records from 40 meteorological observatories over 74 years (1919–1992). The stations are representative of most of the Iberian
Peninsula. The rainfall series were analyzed spatially by means of Principal Component Analysis (PCA) and temporally by means
of the Multi-Taper Method (MTM) of spectral analysis of by Monte-Carlo Singular Spectrum Analysis (MCSSA). The PCA gave six
dominant modes of variation which explain 75% of the variance with each component affecting a different region of the Peninsula.
The spectral analysis showed 7 year oscillations for the dominant pattern and 2.7 and 16 years for the third pattern. The
7-year oscillation seems to be related to other climatic oscillations recorded in the northern hemisphere while the 2.7-year
oscillation could be related to the ENSO phenomenon.
Received July 18, 2000 Revised April 19, 2001 相似文献
143.
Sediment community metabolism associated with continental shelf hypoxia, Northern Gulf of Mexico 总被引:1,自引:0,他引:1
Gilbert T. Rowe Marta Elizabeth Cruz Kaegi John W. Morse Gregory S. Boland Elva G. Escobar Briones 《Estuaries and Coasts》2002,25(6):1097-1106
Net fluxes of respiratory metabolites (O2, dissolved inorganic carbon (DIC), NH4 +, NO3 ?, and NO2 ?) across the sediment-water interface were measured using in-situ benthic incubation chambers in the area of intermittent seasonal hypoxia associated with the Mississippi River plume. Sulfate reduction was measured in sediments incubated with trace levels of35S-labeled sulfate. Heterotrophic remineralization, measured as nutrient regeneration, sediment community oxygen consumption (SOC), sulfate reduction, or DIC production, varied positively as a function of temperature. SOC was inversely related to oxygen concentration of the bottom water. The DIC fluxes were more than 2 times higher than SOC alone, under hypoxic conditions, suggesting that oxygen uptake alone cannot be used to estimate total community remineralization under conditions of low oxygen concentration in the water column. A carbon budget is constructed that compares sources, stocks, transformations, and sinks of carbon in the top meter of sediment. A comparison of remineralization processes within the sediments implicates sulfate reduction as most important, followed by aerobic respiration and denitrification. Bacteria accounted for more than 90% of the total community biomass, compared to the metazoan invertebrates, due presumably to hypoxic stress. 相似文献
144.
Gabriela Polonic 《Tectonophysics》1985,117(1-2)
Based on geological and geophysical data, characteristics of neotectonic activity of the eastern border of the Pannonian Depression are presented.As a result of differential tectonic movements during the Neogene-Quaternary, separate morphostructural units are subjected to subsidence and uplifting, along active faults.The local seismic activity is related, mainly, to the movements along the borders of grabens, as well as at the contact between different crustal blocks. 相似文献
145.
Hans-Rudolf Wenk Erik Rybacki Georg Dresen Ivan Lonardelli Nathan Barton Hermann Franz Gabriela Gonzalez 《Physics and Chemistry of Minerals》2006,33(10):667-676
Mechanical Dauphiné twinning in quartz has been of long-standing interest, both in single crystals and polycrystalline aggregates. This study investigates texture development in fine-grained quartz rock novaculite with no initial texture using compression experiments conducted in the Paterson gas apparatus to explore the influence of stress and temperature. Texture patterns are measured with time-of-flight neutron diffraction and hard synchrotron X-rays, analyzing diffraction data with the Rietveld method. Similar texture patterns are observed as described previously but the new results establish a profound influence of temperature and document that twinning initiates at stresses less than 50 MPa. Possibilities of using Dauphiné twinning as a paleopiezometer in quartz-bearing rocks are discussed. 相似文献
146.
Modern Diatom Assemblages in Surface Sediments from Estuarine Systemsin the Southeastern Buenos Aires Province, Argentina 总被引:1,自引:0,他引:1
Paleoecological reconstructions of Holocene sea-level changes in Argentinean coastal regions were based mainly on ecological
data gathered from other regions, as there was a lack of information on modern estuarine diatom distributions. The aim of
the present work was to assess the spatial variation of diatom assemblages in two representative estuaries of Argentina in
order to gather ecological information for paleoecological reconstructions in the region. The two selected estuaries have
different geomorphologic features and salinity regimes: Mar Chiquita Lagoon is shallow, which prevents the development of
a stable salinity gradient as it occurs in the Quequén Grande River. Surface sediment samples were taken from selected stations
representative of the environmental gradient from the inlet to the inner reaches of both estuaries. Cluster analysis defined
three diatom zones at Mar Chiquita: marine/brackish assemblages dominate the inlet (zone I), where salinity, tidal range and
current speed are higher. The brackish/freshwater tychoplankton Staurosira construens var. venter and Staurosirella pinnata dominate the inner lagoon (zone II), where environmental conditions are very variable and concentrations of suspended sediments
are higher. Brackish/freshwater euryhaline diatoms dominate the headwaters (zone III). On the other hand, the Quequén Grande
River was divided into three diatom zones: coastal taxa are distributed at the inlet (zone I), while the middle estuary (zone
II) is dominated by brackish/freshwater euryhaline taxa. At the upper estuary region (zone III), freshwater diatoms dominate,
and the halophobous Nitzschia denticula increased in abundance values. Diatom distributions were most closely related to the salinity gradient at Quequén Grande
River than at Mar Chiquita Lagoon. Fossil data of a sequence from Mar Chiquita Lagoon (Las Gallinas Creek) were compared to
the modern data set in order to search for analogies between fossil and modern diatom assemblages. DCA results showed that
fossil diatom assemblages have modern counterparts. Most diatom assemblages of Las Gallinas Creek fall within Mar Chiquita
zone III, representing a shallow brackish/freshwater environment, with low salinity fluctuations
(~1–9‰) and no tidal influence. Therefore, our modern diatom data provide useful analogs to interpret paleoenvironments in
the region. 相似文献
147.
Diana Gabriela Lope-Alzina 《Singapore journal of tropical geography》2007,28(1):21-38
This paper examines the influence of gender relations and gendered domains on maize and squash varietal selection in a village in Yucatán State, southeast Mexico. Results of the exploratory study indicate that the traditional production spaces of homegardens and agricultural fields are complementary gendered domains of varietal maintenance for both crops although with different cropping patterns, while a 'new' space, of land allocated to some families for future residential construction ( terreno ) is in the meantime a jointly worked agricultural domain. Women's labour, knowledge and preferences predominate in post-harvest processes. Fieldwork revealed that neither men nor women are independent decision-makers, planning what to grow, where and in what amounts, but that in most aspects of farming the interests of both are accommodated within the household's production spaces. 相似文献
148.
Moreno Wilmer Emilio García Soares Gabriela Borges Pires Júlio César Gall Sotelo Daniela Govoni Moura Cássio Stein 《Geotechnical and Geological Engineering》2021,39(6):4593-4613
Geotechnical and Geological Engineering - A large part of the Guarani Aquifer is located in the state of Rio Grande do Sul (Brazil) and additionally possesses a recharge area located in its central... 相似文献
149.
Herrera Duvan Ricardo Herrera de Castro David Lopes Oliveira Jefferson Tavares Cruz de Oliveira Digenes Custdio 《Surveys in Geophysics》2022,43(3):883-912
Surveys in Geophysics - In this work, we calculated the Curie Point Depth (CPD) for the Brazilian Equatorial Margin using the Fourier and continuous wavelet (CWT) transforms considering a linear... 相似文献
150.
Bedrock bedding,landsliding and erosional budgets in the Central European Alps 总被引:4,自引:0,他引:4
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Fábio Cruz Nunes Romain Delunel Fritz Schlunegger Naki Akçar Peter W. Kubik 《地学学报》2015,27(5):370-378
We explore the controls of the litho‐tectonic architecture on the erosional flux in the 370‐km2 Glogn basin (European Alps). In this basin, the bedding and schistosity of the bedrock dip parallel to the topographic slope on the NW valley flank, leading to a non‐dip slope situation on the opposite SE valley side. While the dip slope condition has promoted the occurrence of landslides (e.g. the c. 30‐km2 deep‐seated Lumnezia landslide), the opposite non‐dip slope side of the valley hosts >100‐m‐deeply incised tributary streams. 10Be concentrations of stream sediments yield catchment‐averaged denudation rates that vary between 0.27 ± 0.03 and 2.19 ± 0.37 mm a?1, while the spatially averaged denudation rate of the entire basin is 1.99 ± 0.34 mm a?1. Our 10Be‐based approach reveals that the Lumnezia landslide front contributes c. 30–65% of the entire sediment budget, although it covers <5% of the Glogn basin. This suggests a primary control of the bedrock bedding on erosion rates and processes. 相似文献