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101.
102.
Geological studies of the area around Katta, in the southern part of the Ratnagiri District of Maharashtra, were carried out with the help of visual remote sensing techniques using LANDSAT imageries on 1:250,000 scale and aerial photographs on 1:60,000 scale. The major stratigraphic units represented in the area under study are the Archean Complex, Kaladgi Supergroup, Deccan Trap, Laterite and Alluvium. The Kaladgis unconformably overlie the Archean metasediments and also at places exhibit faulted contacts with the latter. The major part of the area is covered by a thick evergreen vegetation. The interpretation followed by field work and laboratory work revealed the following:
- The different lithologic units could be delineated on the aerial photographs.
- Different lineaments marked on the imagery were found to be due either to faults or fracture zones. Some of the older faults appear to have been rejuvenated after the formation of the laterites.
- Some of the lithologic horizons can be identified on the Landsat imagery by virtue of their spatial signatures.
103.
Irene Sarkar R. Chander K. N. Khattri V. K. Gaur 《Journal of Earth System Science》1987,96(3):229-238
The paper describes an algorithm for estimating the hypocentral coordinates and origin time of local earthquakes when the
wave speed model to be employed is a layered one with dipping interfaces. A constrained least-squared error problem has been
solved using the penalty function approach, in conjunction with the sequential unconstrained optimization technique of Fiacco
and McCormick. Joint confidence intervals for the computed parameters are estimated using the approach of Bard for nonlinear
problems. These results show that when a hypocentre lies outside the array of recording stations and head waves from a dipping
interface are involved, then its inclination must be taken into account for dip angles exceeding 5°. 相似文献
104.
105.
The plankton collected from three fish ponds shows a considerable variability within a pond, between the ponds and in the course of the year. The individual volumes or weights are (minimum—mean—maximum): Gleotrichia echinulata 41–252–879 μg3, Chlorella vulgaris 18–42–94 μm3, Oscillatoria amphigranulata 99–306–827 μm3, Brachionus plicatilis 1–4.918 μg, nauplia 0.5–1.25–2.35 μg, Mesocyclops hyalinus 4–45–369—μg, Heliodiaptomus viduus 41–202–288 μg, Daphnia carinata 186–1468–4578 μg. 相似文献
106.
Sensitivity of the radar scattering coefficient to the oceanic wind vector in the midangular range for frequencies from L-
to Ku- band is studied. This is based on computations of scattering coefficient via the two-scale scattering theory employing
a semi-empirical model for the ocean spectrum suggested by Fung and Lee and the slope distribution by Cox and Munk. Higher
frequency and incident angles of over 45 degrees seem to yield better wind sensitivity. 相似文献
107.
The earthquake magnitude is a quantity sampling the spectrum of the far-field radiation.With a suit of properly defined magnitudes in a sufficiently broad range of frequencies, the radiated spectrum can be restored and analyzed.A method is proposed for the extraction of stress drop, fault length and seismic moment from magnitudes on a routine basis. Thereby, the theoretical spectrum as predicted by the ω-square model of Aki is utilized.In applying the method to earthquakes which occurred in several parts of Asia over a time-span of 3 years, it is shown that in most cases earthquakes in a given region are characterized by the same stress drop, varying however from region to region. In one region a change of the stress drop with time is found, eventually indicating a change in the state of stress in the particular region during the time interval investigated. 相似文献
108.
109.
The A-type Mayurbhanj Granite Pluton (3.09 Ga), occurring along the eastern margin of the Singhbhum-Orissa Craton, eastern India, represents the final phase of acid plutonism in this crustal block of Archean age. The granite shows a bimodal association with a voluminous gabbroid body, exposed mainly along its western margin, and is associated with the Singhbhum Shear zone. The granite pluton is composed mainly of a coarse ferrohastingsite–biotite granite phase, with an early fine-grained granophyric microgranitic phase and a late biotite aplogranitic phase. Petrogenetic models of partial melting, fractional crystallisation and magma mixing have been advocated for the evolution of this pluton. New data, combined with earlier information, suggest that two igneous processes were responsible for the evolution of the Mayurbhanj Granite Pluton: partial melting of the Singhbhum Granite; followed by limited amount of mixing of acid and basic magmas in an anorogenic extensional setting. The necessary heat for partial melting was provided by the voluminous basaltic magma, now represented by the gabbroid body, emplaced at a shallow crustal level and showing a bimodal association with the Mayurbhanj Granite Pluton. The Singhbhum Shear Zone provided a possible channel way for the emplacement of the basic magma during crustal extension. It is concluded that all three phases of the Mayurbhanj Granite Pluton were derived from the same parent magma, generated by batch partial melting of the Singhbhum Granite at relatively high temperatures (980 °C) and low pressures (4 to <2 kbar) under anhydrous conditions. The coarse ferrohastingsite biotite granite phase shows evidence of limited and heterogeneous assimilation of country rock metasediments. However, the early microgranite phase and late aplogranite phase have not assimilated any metasediments. Compositional irregularities observed along the western margin of the Mayurbhanj Granite Pluton in contact with the gabbro body including a continuous fractionating sequence from quartz diorite to alkali-feldspar granite in the Notopahar area. Gradational contacts between the gabbro and the Mayurbhanj Granite Pluton in the Gorumahisani area etc., may be attributed to a limited amount of mixing between the gabbroid magma and the newly generated Mayurbhanj Granite magma. The mixing was mainly of liquid–liquid diffusive type, with a subordinate amount of mixing of solid–liquid type. Although A-type granites are commonly described as having high total REE (e.g. 270–400 ppm), studies on the late aplogranite phase of the Mayurbhanj Granite show that total REE values (100 ppm) are low. This low REE abundance may be attributed to the progressive residual nature of the Singhbhum Granite source during continued partial melting, when the magmas of the microgranite and coarse granite phases had already been removed from the source region. 相似文献
110.
We estimate spatiotemporal models of average neighborhood single family home prices to use in predicting individual property prices. Average home-price variations are explained in terms of changes in average neighborhood house attributes, spatial attributes,
and temporal economic variables. Models adopting three different definitions of neighborhoods are estimated with quarterly
cross-sectional data over the period 2000–2004 from four cities in Southern California. Heteroscedasticity and autocorrelation
problems are detected and adjusted for via a sequential routine. Results of these models suggest that forecasts obtained using
city neighborhood average price equations may have advantage over forecasts obtained using city aggregated price equations.
相似文献