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961.
Components of geostatistical estimation, developed as a method for ore deposit assessment, are discussed in detail. The assumption that spatial observations can be treated as a stochastic process is judged to be an inappropriate model for natural data. Problems of semivariogram formulation are reviewed, and this method is considered to be inadequate for estimating the function being sought. Characteristics of bivariate interpolation are summarized, highlighting kriging limitations as an interpolation method. Limitations are similar to those of inverse distance weighted observations interpolation. Attention is drawn to the local bias of kriging and misplaced claims that it is an optimal interpolation method. The so-called estimation variance, interpreted as providing confidence limits for estimation of mining blocks, is shown to be meaningless as an index of local variation. The claim that geostatistics constitutes a new science is examined in detail. Such novelties as exist in the method are shown to transgress accepted principles of scientific inference. Stochastic modeling in general is discussed, and purposes of the approach emphasized. For the purpose of detailed quantitative assessment it can provide only prediction qualified by hypothesis at best. Such an approach should play no part in ore deposit assessment where the need is for local detailed inventories; these can only be achieved properly through local deterministic methods, where prediction is purely deductive.EDITOR-IN-CHIEF'S NOTE: The Editorial Board has long recognized the desirability of greater open discussion and comment of timely topics in the journal. Therefore, I solicited the following contribution from Professors Philip and Watson and a response to their paper from Professor Journel. In addition, Journel sent to me comments by a student, Srivastava. None of these three papers has undergone reviewing by other workers in the field as normally is required byMathe-matical Geology. We thank these authors for their papers and hope that these discussions will be beneficial to all our readers. 相似文献
962.
High-quality Earth-based photographs from the Lowell Observatory Planetary Research Center collection have been analyzed to derive some photometric parameters for the Martian south polar cap region during the 1971 apparition. The optical thickness of the atmosphere above the cap varied with wavelength from 0.35 ± 0.05 in red light to 0.58 ± 0.06 inuv light. The effective geometric albedo is calculated from the 30° phase data assuming isotropic scattering; it varies from 0.85 ± 0.04 (in red light) to 0.63 ± 0.05 (in uv light). 相似文献
963.
A sonic well log was obtained within the basement complex of the Walvis Ridge during Deep Sea Drilling Project Leg 74. The
top of the basement complex is characterized by smooth acoustic reflectors. The rocks recovered within the basement complex
consist of basalts with intercalated sediments. According to the log ∼-50% of the upper 75 m of basement are igneous rocks
and the other 50% sedimentary. Sonobuoy results indicate that the ratio of sediments to basalt increases with depth for an
additional 225 m until a typical oceanic velocity structure is observed. Paleontological results suggest that the processes
forming this upper 300 m of the basement complex was accomplished within a short time interval. 相似文献
964.
Diverse global and local measures of variability appear in the geological literature and, along with methods used to apply them, have been subject to some debate. Measures of variability for three data types—replicate, locational, and compositional—are considered; the source and nature of the variability determine the appropriate type of measure. To illustrate the effects of these measures and expose their inadequacy when improperly applied, the variability of a three-column data set is interpreted under three different suppositions. Geologists need to be aware of the confusion and misleading results that can develop from the use of variance as a measure of variability for locational or compositional data. 相似文献
965.
966.
Philip B. Stark 《Geophysical Journal International》1987,89(3):987-996
Summary. The convergence of two methods of inferring bounds on seismic velocity in the Earth from finite sets of inexact observations of τ ( p ) and X( p ) are examined: the linear programming (LP) method of Garmany, Orcutt & Parker and the quadratic programming (QP) method of Stark & Parker. The LP method uses strict limits on the observations of τ and X as its data, while QP uses estimated means and variances of τ and X. The approaches are quite similar and involve only one inherent approximation: they use a finite-dimensional representation of seismic velocity within the Earth. Clearly, not every Earth model can be written this way. It is proved that this does not hinder the methods - they may be made as accurate as desired by increasing the number of dimensions in a specified way. It is shown how to get the highest accuracy with a given number of dimensions. 相似文献
967.
968.
Evaggelos Ntotsios Costas Papadimitriou Panagiotis Panetsos Grigorios Karaiskos Kyriakos Perros Philip C. Perdikaris 《Bulletin of Earthquake Engineering》2009,7(2):469-483
A bridge health monitoring system is presented based on vibration measurements collected from a network of acceleration sensors.
Sophisticated structural identification methods, combining information from the sensor network with the theoretical information
built into a finite element model for simulating bridge behavior, are incorporated into the system in order to monitor structural
condition, track structural changes and identify the location, type and extent of damage. This work starts with a brief overview
of the modal and model identification algorithms and software incorporated into the monitoring system and then presents details
on a Bayesian inference framework for the identification of the location and the severity of damage using measured modal characteristics.
The methodology for damage detection combines the information contained in a set of measurement modal data with the information
provided by a family of competitive, parameterized, finite element model classes simulating plausible damage scenarios in
the structure. The effectiveness of the damage detection algorithm is demonstrated and validated using simulated modal data
from an instrumented R/C bridge of the Egnatia Odos motorway, as well as using experimental vibration data from a laboratory
small-scaled bridge section. 相似文献
969.
970.
Uncertainty in floodplain delineation: expression of flood hazard and risk in a Gulf Coast watershed
Jason Christian Leonardo Duenas‐Osorio Aarin Teague Zheng Fang Philip Bedient 《水文研究》2013,27(19):2774-2784
This paper investigates the development of flood hazard and flood risk delineations that account for uncertainty as improvements to standard floodplain maps for coastal watersheds. Current regulatory floodplain maps for the Gulf Coastal United States present 1% flood hazards as polygon features developed using deterministic, steady‐state models that do not consider data uncertainty or natural variability of input parameters. Using the techniques presented here, a standard binary deterministic floodplain delineation is replaced with a flood inundation map showing the underlying flood hazard structure. Additionally, the hazard uncertainty is further transformed to show flood risk as a spatially distributed probable flood depth using concepts familiar to practicing engineers and software tools accepted and understood by regulators. A case study of the proposed hazard and risk assessment methodology is presented for a Gulf Coast watershed, which suggests that storm duration and stage boundary conditions are important variable parameters, whereas rainfall distribution, storm movement, and roughness coefficients contribute less variability. The floodplain with uncertainty for this coastal watershed showed the highest variability in the tidally influenced reaches and showed little variability in the inland riverine reaches. Additionally, comparison of flood hazard maps to flood risk maps shows that they are not directly correlated, as areas of high hazard do not always represent high risk. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献