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741.
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Matthew Colless Gavin Dalton Steve Maddox Will Sutherland Peder Norberg Shaun Cole Joss Bland-Hawthorn Terry Bridges Russell Cannon Chris Collins Warrick Couch Nicholas Cross Kathryn Deeley Roberto De Propris Simon P. Driver George Efstathiou Richard S. Ellis Carlos S. Frenk Karl Glazebrook Carole Jackson Ofer Lahav Ian Lewis Stuart Lumsden Darren Madgwick John A. Peacock Bruce A. Peterson Ian Price Mark Seaborne Keith Taylor 《Monthly notices of the Royal Astronomical Society》2001,328(4):1039-1063
745.
Abstract— The Kirbyville meteorite is an equilibrated monomict eucrite with a mode (calculated in wt.%): plagioclase 37, inverted pigeonite 58, silica 3, ilmenite 1.4 and troilite 0.3. The pyroxene compositional range is Wo 2–42, Fs 27–62, En 30–40 with an average of Wo 7. The plagioclase average mean is An 89. Kirbyville is one of the “main group” eucrites. 相似文献
746.
Much writing on changing trends in geographical practices is based on subjective interpretations of the discipline’s scholarly output. This paper introduces a data source which provides quantitative information on the discipline’s lexicon through full-text searching of the contents of five of the discipline’s major Anglophone journals. Analysis of the large data set identifies two main trends in geography’s language and practices during the period 1950-1998: one group of terms associated with quantitative work became prominent in the 1970s but declined in relative importance thereafter - though by no means disappearing from the lexicon; the other, comprising a range of terms generally associated with cultural and social geography, increased in prominence from the 1980s on. 相似文献
747.
In his paper Kossobokov investigates the efficiency of our short-term forecast for two western Pacific regions. Although we agree with the basic results of his evaluation that the forecast statistics is much better than a random guess, we have reservations about his definition of earthquake prediction, some of his tests, and his interpretation of the test results. We distinguish between deterministic earthquake predictions and statistical forecasts. We argue that some techniques used by Kossobokov may not be appropriate for testing our forecasts and discuss other testing methods, based on the likelihood function. We demonstrate that Kossobokov's null hypothesis may be biased, and this bias can influence some of his conclusions. We show that contrary to Kossobokov's statement, our algorithm predicts mainshocks when they are preceded by foreshocks. 相似文献
748.
R. J. M. Farla H. Kokkonen J. D. Fitz Gerald A. Barnhoorn U. H. Faul I. Jackson 《Physics and Chemistry of Minerals》2011,38(5):363-377
The rate of static dislocation recovery in Fo90 olivine has been studied under conditions of high temperature and controlled atmosphere in compressively deformed polycrystals
hot-pressed from synthetic (sol–gel) and natural (San Carlos) precursor powders. The sol–gel olivine, containing a small fraction
of orthopyroxene, was deformed to a final strain of 19% with a maximum differential stress of 266 MPa whereas the San Carlos
specimen was deformed to 15% strain and 260 MPa differential stress. Small samples cut from these deformed materials were
annealed under high-temperature, controlled atmosphere conditions, for different durations to allow partial recovery of the
dislocation sub-structures. Oxidative-decoration of the microstructural features, followed by backscattered electron imaging
at 5 kV and image analysis, was used to determine dislocation density. The variation of dislocation density ρ with time t at absolute temperature T was fitted to a second-order rate equation, in integral form, 1/ρ(t) − 1/ρ(0) = kt with k = k
0 exp(−E
a/RT). The activation energy E
a of the recovery process is 240 ± 43 and 355 ± 81 kJ mol−1 for sol–gel and San Carlos olivine polycrystals, respectively. The measured rates are one to two orders of magnitude lower
than those reported in previous studies on natural single crystal olivine. The difference may be explained by several factors
such as high dislocation densities measurable from large areas at high magnification for the SEM and the technique used to
estimate dislocation densities. Comparison between fine-grained sol–gel olivine and the coarser-grained San Carlos olivine
aggregate did not indicate that grain boundaries play an important role in dislocation recovery, but the absence of grain
boundaries might also have contributed to the high dislocation recovery rates previously measured for single crystals. 相似文献
749.
We present a two-shell polarization model for the α-quartz and α-cristobalite structures. By allowing for polarization, we correct problems encountered in purely ionic bonding treatments of tetrahedrally coordinated silica phases. The shell model predicts zero pressure structures in very good agreement with experiment using no empirical parameters. The behavior of the shell model α-quartz lattice upon compression shows dramatic improvement over the distorted, rigid lattice given by the ionic model. 相似文献
750.