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171.
The article focuses on the way in which map content reflects the cartographer's World view and system of values. Different
World views are illustrated historically. Examples of topographical, land-use and vegetation maps from different parts of
the World indicate the prevalence of Eurocentric perceptions in cartography. Different geological maps of Norden show how
the visual image depends on the classification system adopted. All maps are mental maps in that their content is culturally
determined and ethnocentric in origin. 相似文献
172.
The Mgb1 line profile is studied as a function of spatial position in the sunspot region. Comparing the wavelengths of the core and the wing, in and just outside the penumbra, a reversal in the shift is detected. The displacements of the core and the wing are interpreted as horizontal motions directed into the spot in the chromosphere and as a flow directed out of the spot in deeper layers.Systematic wavelength shifts are detected in the line core in some regions outside the penumbra. This is interpreted as a chromospheric velocity field usually directed horizontally away from the spot. 相似文献
173.
A 14C-dated magnetostratigraphy of absolute declination and inclination between 12500 and 10000 14C yr BP was recently developed for southern Sweden. Recently also the Swedish geochronological time-scale, based on c. 11 500 annually deposited clay-varves, was connected with the present. It should therefore be possible to compare the two chronologies with a reliable magnetostratigraphic record in an appropriate clay-varve section. We have found such a site within the Middle Swedish end-moraine zone. Statistical correlations between the two independently dated time-scales suggest that at 10500–10200 14Cy r BP the varve chronology exceeds the 14C chronology by the order of 500-600 varve yr. Other correlations indicate that the difference between the two chronologies was less at 11000 14C yr BP, and further correlations between the time-scales at 12000 14C yr BP suggest that the difference between the chronologies increased steadily from 12000 to 10000 14C yr BP. If these correlations are correct they imply that the 14C production rate increased steadily during the Late Weichselian. 相似文献
174.
Jørgen Christensen-Dalsgaard 《Astrophysics and Space Science》2003,284(1):277-294
The workshop took place at the beginning of what promises tobe a golden age of asteroseismology.Ground-based instrumentation is finally reaching a level of stabilitywhich allows detailed investigations of solar-like oscillations in atleast bright, slowly rotating main-sequence stars.Very extensive results are expected from the coming space missions,including data on a broad range of stars from the Eddington mission.The observational situation is therefore extremely promising.To make full use of these promises, major efforts are requiredtowards the efficient utilization of the data, through the developmentof techniques for the analysis and interpretation of the data.A broad range of topics related to these issues is discussed in the presentproceedings. Here I review some of the relevant problems,relate the asteroseismic investigations to broader areas of astrophysics and consider briefly the basis for our great expectations for the developmentof the field. 相似文献
175.
Eberhart Jensen 《Solar physics》1982,77(1-2):109-119
Three quiescent prominences were observed in the Ca ii K-line and a fourth one also in the H-line at Oslo Solar Observatory, Harestua, and reduced by Rustad (1974) and by Engvold et al. (1980). These data are used to study the distribution of the line-of-sight velocity component, N(u
0). It is pointed out that in a stationary and isotropic case, N(u
0) should be a gaussian distribution. For each of the sets of measurements gaussians were therefore fitted by a least square procedure. The range in observed velocities varies considerably between the prominences. For the best observed prominence more than 70% of the kinetic energy is in the supersonic range. In the other cases none or only an insignificant part of the observations exceed the velocity of sound. Considerable deviations from gaussian distributions are apparent for the smallest velocities. This distortion shows up conspicuously in the slope of the energy spectrum, a parameter that may be used as a rough measure of spectral resolution.If it is assumed that we have to do with MHD-turbulence as described by Kraichnan (1965), a characteristic relationship should exist between velocity and eddy size. When supersonic velocities are present, compressibility effects may severely alter this relationship. The possibility of observational confirmation is discussed.If a turbulent velocity field is indeed present, the heat conductivity and other transport coefficients may be significantly altered as compared to the atomic values. 相似文献
176.
177.
The influence of an internal boundary layer and a roughness sublayer on flux–profile relationships for momentum and sensible heat have been investigated for a closed beech forest canopy with limited fetch conditions. The influence was quantified by derivation of local scaling functions for sensible heat flux and momentum (h and m) and analysed as a function of atmospheric stability and fetch. For heat, the influences of the roughness sublayer and the internal boundary layer were in agreement with previous studies. For momentum, the strong vertical gradient of the flow just above the canopy top for some wind sectors led to an increase in m, a feature that has not previously been observed. For a fetch of 500 m over the beech forest during neutral atmospheric conditions, there is no height range at the site where profiles can be expected to be logarithmic with respect to the local surface. The different influence of the roughness sublayer on h and m is reflected in the aerodynamic resistance for the site. The aerodynamic resistance for sensible heat is considerably smaller than the corresponding value for momentum. 相似文献
178.
179.
Trace element distribution during the reproductive cycle of female and male spiny and Pacific scallops, with implications for biomonitoring 总被引:1,自引:0,他引:1
Trace element concentrations and contents in gills, gonad, kidneys, mantle, muscle and remainder during the reproductive cycle of female and male spiny and Pacific scallops, from the Strait of Georgia, BC, Canada, were quantified by using ICPMS. The elements investigated were chromium, manganese, iron, cobalt, nickel, selenium, molybdenum, cadmium, tin and mercury. For all ten elements, the tissue distribution was to some extent influenced by species, sex and reproductive status. The implications of the present study in relation to the design of biomonitoring programmes are: (1) care should be taken to ensure an equal/constant sex composition when making interannual comparisons of pooled samples. Preferably the sexes should be monitored separately. (2) the practice of obtaining pooled samples in the interspawn phase is applicable only to monitoring long-term trends in contaminant levels, while the reproductive status should be heeded when studying short-term changes. (3) the present study confirms that direct temporal or spatial comparisons of absolute accumulated element concentrations are only valid intraspecifically. 相似文献
180.
F. Primdahl A. Bahnsen M. Ejiri P. Høeg G. Marklund B.N. Mæehlum J.K. Olesen E. Ungstrup L.J. Zanetti 《Planetary and Space Science》1984,32(5):561-583
Results are reported from a rocket experiment conducted at Søndre Strømfjord, Greenland, on 22 August 1976, at 16.00 M.L.T. A series of plasma, particles, and fields and wave experiments were carried on board the payload, and the venture was supported by data from the AE-C satellite and by groundbased ionosondes and magnetometers at the launch site and at Godhavn. Two regions of field-aligned electron precipitation, electron density and temperature enhancements, and field-aligned upflowing current sheets were intercepted by the rocket. The density enhancements were also observed by groundbased ionosondes. Significant discrepancies were found between the currents carried by the streaming electrons in the 0.15–10 keV range and the upflowing currents seen by the on board magnetometer, suggesting that the upflowing current could not be the primary driver of the electron acceleration mechanism. The E-region was unstable to the combined Gradient-Drift and Farley-Buneman instability, and plasma turbulence was observed in situ, but the absolute density fluctuations were too small to return detectable HF-radar power to the ground. 相似文献