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991.
M. K. Pavićević V. Cvetković G. Amthauer A. Bieniok B. Boev F. Brandstätter M. Götzinger R. Jelenković D. Prelević T. Prohaska 《Mineralogy and Petrology》2006,88(3-4):527-550
Summary Results of a multidisciplinary study on quartz concentrates (mineralogically separated) and etched concentrates (stoichiometric
quartz) from three locations at Allchar (Macedonia) are presented. The investigation of quality and composition of these quartz
samples is of great interest because the same material has been previously used as monitor for 26Al Acceleration Mass-Spectrometry (AMS) erosion rate estimates. Two genetically different types of quartz are distinguished
in the studied samples which petrologically can be described as hydrothermally altered dacites or quartz latites; i.e. volcanic
(QV) and hydrothermal (QH) quartz with relative proportions of QH:QV around 3:2. QH is genetically related to the Allchar Sb–As–Tl–S mineralization having very high Sb (85–785 ppm), As (7.6–78 ppm) and (Tl
3.3–4.0 ppm) contents. This type of quartz is also characterized by very high Li (129–138 ppm), Al (2424–2520 ppm) and Ti
(153–219 ppm) concentrations. QV appears to be much less enriched in trace elements having Al and K contents ranging from 0 to 280 ppm and from 50 to 85 ppm,
respectively. 26Al AMS measurements were done on the samples containing two genetically different types of quartz but this had no effects
on the interpretation and erosion rate determinations. However, the extremely high Al concentrations in the analyzed quartz
have generally negative effects, mainly by decreasing 26Al/27Al ratios and thus causing an increase of the detection limit. The disagreement between the results of 26Al AMS analyses and quantitative geomorphologic data for one location is probably caused by different geographical position
with respect to the direction of cosmic rays. 相似文献
992.
T. B. Pyatunina D. C. Gabuzda S. G. Jorstad N. A. Kudryavtseva M. F. Aller H. D. Aller H. Teräsranta 《Astronomy Reports》2006,50(6):468-482
Our earlier joint analysis of light curves for the blazar 0059+581 at 4.8, 8, 14.5, 22, and 37 GHz with high-resolution VLBI images led us to suggest that the activity in this source develops in cycles, or periods, with a duration of about four years, with a “typical scenario” for the development of the source’s activity taking place over a cycle. Based on this analysis, we predicted in 2002 that a new superluminal component would be ejected from the core of this source in a structural position angle ~170° no later than by the end of 2003. A 43-GHz VLBI image obtained on September 14, 2003, as part of a program to monitor the structure of reference sources used for a radio astronomical coordinate system, convincingly confirms the correctness of this prediction. This is the first time in the history of radio astronomy that a new superluminal component has been detected at a predicted time and in a predicted structural position angle. 相似文献
993.
It is possible to reconstruct the past variation of an environmental variable from measured historical indicators when the
modern values of the variable and the indicators are known. In a Bayesian statistical approach, the selection of a prior probability
distribution for the past values of the environmental variable can then be crucial and the selection therefore should be made
carefully. This is particularly the case when the data are noisy and the statistical model used is complex since the influence
of the prior on the results can then be especially strong. It can be difficult to elicit the prior probability distribution
from the available information, since usually there are no measured data on the past values of the variable one wants to reconstruct
and different reconstructions are typically consistent with each other only at a coarse level. To overcome these difficulties
we propose to use a non-informative smoothing prior, possibly in combination with an informative prior, that simply penalizes
for roughness of the reconstruction as measured by the variability of its values. We believe that it can sometimes be easier
to set an overall prior distribution on the roughness than to agree on a prior for the actual values of the reconstructed
variable. Note that by using a smoothing prior one incorporates into the model itself the smoothing step usually done before
or after the actual numerical reconstruction. Another idea proposed in this paper is to integrate the reconstruction model
with a multiscale feature analysis technique known as SiZer. Multiscale analysis of the posterior distribution of the reconstructed
variable makes it possible to infer its statistically significant features such as trends, maxima and minima at several different
time scales. While only temperature is considered in this paper, the technique can be applied to other environmental variables. 相似文献
994.
K. Stojanović Br. Jovančićević Dr. Vitorovi G. S. Pevneva Ju. A. Golovko A. K. Golovko 《Geochemistry International》2007,45(8):781-797
Aiming at improved classification of crude oils, naphthalene and phenanthrene isomerization and dealkylation processes were
considered in detail as a possible basis to select new maturation parameters. Crude oils originating from the Banat depression
(Southeastern Pannonian Basin, Serbia) were used as objects of our study. Four new maturation parameters are proposed in this
paper. Two of them are based on dimethylnaphthalene (DMN) and trimethylnaphthalene (TMN) isomerization reactions: DNx = (1,3-DMN + 1,6-DMN)/(1,4-DMN + 1,5-DMN) and TNy = (1,3,6-TMN + 1,3,7-TMN)/(1,3,5-TMN + 1,4,6-TMN). The other two are based
on demethylation of dimethyl-and trimethylphenanthrenes (DMP and TMP) into corresponding methylphenanthrenes (MP): MDR = ΣMP/ΣDMP
and MTR = ΣMP/ΣTMP. The new parameters’ advantageous applicability was demonstrated by factor analysis, comparing them with
maturation parameters known from literature.
The text was submitted by the authors in English. 相似文献
995.
Andreas Dittrich Annette Schulte-Rentrop Michael Marek Volker Späth 《Acta Geophysica》2007,55(1):33-46
Flow in rivers and on floodplains is complex as it is affected by several interconnected factors such as topography, sediment
transport and vegetation characteristics. The resulting processes are explained by the measure “Hartheim” planned for retention
purposes at the Upper Rhine river. On the basis of existing formulas and instruments it is demonstrated that a good estimation
of the development of the measure is possible. The proposed procedure is a useful tool for estimating morphological developments
of restored river sections. 相似文献
996.
Adrien Oth Friedemann Wenzel Hillel Wust-Bloch Ellen Gottschämmer Zvi Ben-Avraham 《Pure and Applied Geophysics》2007,164(1):23-37
3-D simulations of elastic wave propagation generated by earthquakes with magnitudes between 5.5 and 7.0 are used to parameterize
strong ground motion attenuation relations for the Dead Sea Rift (DSR) graben structure. The results show that standard attenuation
relations with an isotropic distance parameter are inadequate for a graben structure with a deep sedimentary trough. A new
strategy is devised for the parameterization of attenuation relations in graben structures by looking at the statistical properties
of 53 simulated earthquakes of variable magnitudes located at various sites along the western boundary fault of the DSR graben.
An exemplary attenuation relation is designed from the synthetics for the 1 Hz spectral acceleration, modifying the Joyner-Boore-type
parametrization by adding coefficients suited for three different source-to-sensor configurations: within the graben, beyond
the graben and path unaffected by the graben structure. 相似文献
997.
Coupling of groundwater and surface water at Lake Willersinnweiher: Groundwater modeling and tracer studies 总被引:1,自引:0,他引:1
998.
999.
F. W. Jäger 《Solar physics》1972,27(2):481-488
It is shown in detail in which way magnetographic measurements may be affected by instrumental polarization. To eliminate this influence we propose a combined method of partial compensation and computation practicable successfully with only a moderate expenditure of calculations and instrumental equipment. 相似文献
1000.
Lauri Ryynänen 《Astrophysics and Space Science》1970,8(3):497-501
Pulsars at different galactic latitudes have different periods. It seems possible that there are two different types of pulsars. 相似文献