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291.
Different extractants were used to determine various forms of Fe and Al in three soil profiles developed under a tropical environment in India. The average contents of Fe and Al, extracted by different extracting reagents were found to be in descending order, as follows:
Analysis of pyrophosphate (pyr), oxalate (oxa) and dithionate (dith) extractable Fe and Al showed that with increasing soil age, the crystalline Fe and Al oxides increased at the expense of the poorly crystalline forms. The mean content of amorphous Fe and Al, crystalline Fe and Al and their ratio values in the three different soil series estimated the degree of soil development and were found to be in the following descending order: Ghoradanga >Kanchanpur >Lachimpur. Correlation between different forms of Fe and Al and selected soil properties were examined. Multiple regression equations were formulated to show the relation among soil properties and different forms of Fe and Al. 相似文献
292.
We examine spectral time series of the transition region line Ov 629Å, observed with the Coronal Diagnostic Spectrometer (CDS) on the SOHO spacecraft in July 1997. Both Fourier and wavelet transforms have been applied independently to the analysis of plume oscillations in order to find the most reliable periods. The wavelet analysis allows us to derive the duration as well as the periods of the oscillations. Our observations indicate the presence of compressional waves with periods of 10–25 min. We have also detected a 11±1 min periodicity in the network regions of the north polar coronal hole. The waves are produced in short bursts with coherence times of about 30 min. We interpret these oscillations as outward propagating slow magneto-acoustic waves, which may contribute significantly to the heating of the lower corona by compressive dissipation and which may also provide enough energy flux for the acceleration of the fast solar wind. The data support the idea that the same driver is responsible for the network and plume oscillations with the network providing the magnetic channel through which the waves propagate upwards from the lower atmosphere to the plumes. 相似文献
293.
We present observations of Ovi 1032 Å line profiles obtained with the SUMER instrument on SOHO extending from the solar disk to 1.5 R
above the limb in the north polar coronal hole. Variations of the intensity and linewidth in the polar plume and inter-plume regions are investigated. We find an anti-correlation between the intensity and the linewidth in the plume and inter-plume regions with detailed plume structures been seen out to 1.5 R
. Possible implications regarding the magnetic topologies of these two regions and related heating mechanisms are discussed. The Ovi linewidth measurements are combined with UVCS output to provide an overview of its variations with height extending up to 3.5 R
. We find a linear increase of the linewidth from 1 to 1.2 R
, then a plateau followed by a sharp increase around 1.5 R
. 相似文献
294.
295.
The paper considers inhomogeneous space-times admitting a two-parameter group of motions and satisfying Einstein's field equations for viscous fluid and perfect fluid with heat conduction. Some homogenous solutions representing viscous fluid have also been obtained for which the free-gravitational field is of the magnetic type. Various physical and kinematical properties have been discussed. 相似文献
296.
Biotite crystals were counted in standard thin sections which originated from the diamond drill core of the mafic norite formation at Strathcona mine, Sudbury Nickel Irruptive. Pearson's method of moments is suitable to fit Types III and VII to the biotite data and its log
10
transformation values, as the number of samples (thin sections)is large (351).Based on the two models and the Edgeworth series (utilizing the log
10
data)probability values p,that biotite occurrences lie in the interval mean ± Z standard deviations is derived. Results are compared with the usual normal probability values pZ
corresponding to Zand it is shown that the Edgeworth series generated the largest pvalues for intervals when pZ
values are large; for intermediate or lower pZ
s. Types VII and III models produced larger ps, relative to the Normal and the Edgeworth series. 相似文献
297.
Sunirmal Banerjee 《国际地质力学数值与分析法杂志》1986,10(5):555-561
A review of literature reveals that regardless of the configuration of electro-osmotic cells, all previous laboratory investigations and interpretations have been based on the assumption of a constant potential gradient in the specimen. Appropriate solutions for electrical potentials for cylindrical cells are presented in this paper. 相似文献
298.
The average directions of natural remanent magnetization (NRM) of three texturally distinct layers (72215, 72255, and 72275) of a 2 m-sized breccia boulder were found to be the same, while the directions of their stable components of NRM were found to be widely divergent. One clast from 72275 yielded a stable NRM direction which was different from that of the matrix. Approximate paleointensity measurements showed that 72255 and 72275 could have obtained their stable remanence from an ancient magnetic field of the same magnitude. However, 72215 probably was magnetized by a magnetic field of a different intensity. We concluded that the coincident NRM directions owe their origin to a secondary imprint of less stable magnetization imparted during the assembly of the boulder at moderate temperatures (~ 450°C) on the South Massif. The stable directions, on the other hand, date from the last, higher-temperature (~ 770°C) magnetizing event experienced by the mineral and lithic components while they were part of the immature pre-Serenitatis regolith. 相似文献
299.
The sorption of lead (II) and cadmium (II) on seven shales belonging to the Proterozoic Vindhyan basin, central India, and a black cotton soil, Mumbai, India, was studied and compared with sorbent geochemistry. The sorption equilibrium studies were conducted under completely mixed conditions in batch reactors (pH=5.0 and ionic strength= 0.01 M) at room temperature. The Freundlich model provided better fits to the experimental data compared to Langmuir model. High cadmium and lead sorption was observed for the calcareous shales with greater than 5% CaCO3. The Freundlich isotherm parameter relating to sorption capacity, i.e., KF, yielded a strong correlation with the calcium carbonate and calcium oxide content across the various geosorbents studied. The observed sorption pattern may be attributed to complex formation of CaCO3 with Pb2+ and Cd2+ leading to surface precipitation. Moreover, the Ca2+ present in the sorbents may also involve in ion exchange reaction with lead and cadmium. 相似文献
300.
J. N. Goswami D. Banerjee N. Bhandari M. Shanmugam Y. B. Acharya D. V. Subhedar M. R. Sharma C. N. Umapathy P. Sreekumar M. Sudhakar L. Abraham P. C. Agrawal 《Journal of Earth System Science》2005,114(6):733-738
The Chandrayaan-1 mission to the Moon scheduled for launch in late 2007 will include a high energy X-ray spectrometer (HEX)
for detection of naturally occurring emissions from the lunar surface due to radioactive decay of the238U and232Th series nuclides in the energy region 20–250 keV. The primary science objective is to study the transport of volatiles on
the lunar surface by detection of the 46.5 keV line from radioactive210Pb, a decay product of the gaseous222Rn, both of which are members of the238U decay series. Mapping of U and Th concentration over the lunar surface, particularly in the polar and U-Th rich regions
will also be attempted through detection of prominent lines from the U and Th decay series in the above energy range. The
low signal strengths of these emissions require a detector with high sensitivity and good energy resolution. Pixelated Cadmium-Zinc-Telluride
(CZT) array detectors having these characteristics will be used in this experiment. Here we describe the science considerations
that led to this experiment, anticipated flux and background (lunar continuum), the choice of detectors, the proposed payload
configuration and plans for its realization 相似文献