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81.
The flow and turbulence quantities governing dispersion in katabatic flows vary with both height and downslope distance. This variation cannot be accounted for in conventional plume dispersion models. In this study, three random-walk models of varying complexity are formulated to simulate dispersion in katabatic flows, and their strengths and weaknesses are discussed. The flow and turbulence parameters required by these models are determined from a high-resolution two-dimensional katabatic flow model based on a turbulent kinetic energy closure. Random-walk model calculations have been performed for several values of source height and slope angle to examine the influence of these parameters on dispersion. Finally, we simulated the perfluorocarbon and heavy methane tracer releases for Night 4 of the 1980 ASCOT field study over a nearly two-dimensional slope in Anderson Creek Valley, California. The observed peak concentrations are generally well-predicted. The effects of the pooling of the drainage air could not be taken into account in our katabatic flow model and, consequently, the predicted concentrations decay much more rapidly with time than the observed values. 相似文献
82.
Summary Crosscorrelation structure between solar activity and drought indices is investigated by analyzing the cross correlation of the residual time series of solar activity and drought indices. Double Sunspot Cycle, Zürich Sunspot number, Palmer's Drought Index and Drought Area Index data are used in the study. White residual series derived from the observed data series by using valid time series models are used for the crosscorrelation analysis. Weak correlations between solar activity and drought area indices are inferred. The lags of significant correlation appear to vary for the different time series used in the study.With 3 Figures 相似文献
83.
84.
85.
Two examples are given for comparing applications and limitations of four methods which can be used to deal with error propagation in geochemical calculations.The examples indicate that the Monte Carlo method can also be employed to evaluate the effect of covariance.A special function of the method for covariance matrix shown here can reveal the correlations of middle variables relative to the independent primary variables. 相似文献
86.
A S Subrahmanyam K S R Murphy T C S Rao M M Malleswara Rao S Lakshminarayana K Venkateswarlu 《Journal of Earth System Science》1994,103(1):17-26
A detailed analysis of bathymetry and magnetic data of Visakhapatnam-Paradip shelf, east coast of India revealed three major
structural lineaments over the shelf/slope of the area. Models derived from the anomalies associated with the trends indicate
that trend A represents horst and graben type continental basement while trend B is due to a series of dyke intrusions. Trend
C off Chilka lake forms the northward extension of 85°E lineation from deep sea Bengal Fan.
A two stage evolution of the eastern continental margin of India has been inferred from the study of this part of the margin,
viz., the rift stage evidenced by dyke intrusions of reverse polarity located within the inner part of the shelf and post-rift
stage characterized by vertical tectonics in the form of a horst and graben type continental basement. The hotspot related
aseismic 85°E ridge further complicated the tectonics of this part of the area. 相似文献
87.
The atmospheric heat sources of large plateaus strongly influence the general circulation particularly in the summer season. The Bolivian plateau and the adjacent areas affect the upper tropospheric flow in a typical summer month by developing an anticyclone and deflecting the prevailing westerlies. The plateau initially warms the atmosphere through sensible heating and then through latent heating as thunderstorms develop.The atmospheric heat source over the Bolivian and adjacent plateau was computed employing conventional surface and satellite radiation data for the mean January 1979. Because of a lack of direct ground temperature data, the surface radiation was estimated following an empirical formula devised for some earlier Tibetan studies.The results revealed that the latent heating developing in the eastern and northeastern part of the plateau is the biggest contributor to the atmospheric heat source (500 W m-2). A comparison of these results against similar recent results from Tibet showed that the atmospheric heat source in South America is stronger than that over Tibet, primarily because of increased rainfall over Bolivia. 相似文献
88.
Analysis of gravity anomalies over an inclined fault with quadratic density function 总被引:3,自引:0,他引:3
D. Bhaskara Rao 《Pure and Applied Geophysics》1985,123(2):250-260
An attempt is made to interpret the gravity anomalies over an inclined fault with variable density contrast. The decrease of density contrast with depth in sedimentary rocks is approximated by a quadratic function. The anomaly equation of an inclined fault is derived with the quadratic density function. The constantsa
0,a
1 anda
2 of the quadratic density function can be found from the known density-depth values. A synthetic anomaly profile of the fault model is interpreted by the non-linear optimisation technique using the Marquardt algorithm. The distances are measured from an arbitrary reference point and thus the origin of the fault model is also treated as an unknown parameter. For the assumed values of the constantsa
0,a
1 anda
2, the various parameters of the fault model are found by the non-linear optimisation technique. The convergence of the method is shown by plotting the values of the objective function, lamda, and the parameters of the fault model with respect to iteration number. The two parameters inclination and origin are found to be correlated. The same program is used to interpret the gravity anomalies with different density contrasts. Finally, the use of modelling with the quadratic density function is discussed. 相似文献
89.
R. Nagendra I. B. Ramaprasada Rao Satyanarayan Kabra 《Journal of Earth System Science》1985,94(3):269-277
The transient electromagnetic response due to a pair of horizontal conducting sheets induced by a loop field is obtained.
The response characteristics in the three different regions (above the upper sheet, between the two sheets and below the lower
sheet) are briefly discussed.
In the first and second regions the composite response is characterised by an overburden response asymptote during early times
and a target response asymptote during late times. The transition zones are characterised by shoulder-like bends. In the third
region, the composite response increases in direct proportion to the induction number, eventually merging with the target
response for large values of the induction number. 相似文献
90.