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991.
Measured concentration levels of carbon monoxide present in the atmosphere near the ground surface have been studied in relation to atmospheric stability inferred from acoustic sounder vis-à-vis the density of motor-vehicular traffic responsible for the emission of carbon monoxide gas. It has been seen that concentration levels of carbon monoxide during peak traffic hours depend on the prevailing stability of the atmosphere. The need for continuous monitoring of atmospheric stability at a place using acoustic sounder to assess air quality has been emphasized. 相似文献
992.
Chandra S Rai Shiv K Sharma David W Muenow Dean W Matson Charles D Byers 《Geochimica et cosmochimica acta》1983,47(5):953-958
The temperature dependence of carbon dioxide solubility in glasses of diopside composition, quenched from 20 kbar, has been investigated using a combination of high-temperature mass spectrometry and Raman spectroscopy.CO2-charged diopside glasses were synthesized in a piston-cylinder apparatus. Because of diffusion of hydrogen through the platinum capsules, significant amounts of H2O, CH4 and CO were detected along with CO: in the diopside glasses. All three carbon species show a bimodal release pattern in the mass pyrograms. The CO2 solubility shows a linear and negative temperature dependence. We do not observe any maxima in the solubility curve as was reported previously (Mysen and virgo, 1980a).None of the additional bands observed in Raman spectra of CO2-charged diopside glasses compared to those in the spectrum of diopside glass can be assigned to molecular CO2. These bands are caused by CO?23 ions and indicate that the physical solubility of molecular carbon dioxide is negligible. The bimodal release pattern observed for CO2 in the mass pyrograms, is consistent with the Raman data which strongly suggests that CO?23 ions are present in at least two distinct sites in the glass. 相似文献
993.
994.
Forecasts of runoff volumes are required in order to maximize the utility of water-supply sources. In remote areas where hydrologic and land-use data are sparse, forecast models are needed; such models should be conceptually rational so they can be transferred to remote watersheds where data are sparse. A series of models were calibrated for a large watershed in India. A spatially-distributed seasonally-varying model having a structure similar to the rational method was found to provide precise, unbiased estimates of 10-day streamflow volumes. The model was tested on a watershed that was not used for calibration, with the results indicating a high correlation between the observed and measured streamflow. Thus, the model should provide good estimates of streamflow volumes on other ungaged watersheds. 相似文献
995.
ABSTRACT Use of granular pile as a ground improvement technique in case of soft soils is one of the reliable and economic options. Analysis of a partially stiffened group of granular floating piles has been numerically assessed and presented here. Partial stiffening simply means that instead of using conventional material for making the granular pile (GP) in its full length, top region is replaced partially by some suitable material, having better mechanical properties, i.e. higher deformation modulus. Various normalised parameters like settlement influence factor for top of GP, settlement interaction factor, settlement reduction factor, percentage load shared by the base and shear stress distribution along the length of the granular pile are evaluated. The settlement influence factor for top of GP is found to decrease with the increase in the values of the stiffening parameters. The interfacial shear stresses get redistributed along the length of the granular pile. 相似文献
996.
Summary The Karimnagar granulite terrain is an integral part of the Eastern Dharwar Craton (EDC). It has received much interest because
of the only reported granulite facies rocks in the EDC. These granulites contain quartz-free sapphirine-spinel-bearing granulites,
kornerupine – bearing granulites, mafic granulites, orthopyroxene-cordierite gneisses, charnockites, amphibolites, dolerite
dykes, granite gneisses, quartzites and banded magnetite quartzite. The orthopyroxene-cordierite gneisses occur as enclaves
within granite-gneiss in association with banded magnetite quartzites, charnockites and amphibolites. The observed reaction
textures, spectacular as they are, have an extraordinary information content within a tiny domain. Coronas, symplectites and
resorption textures are of particular interest as they reflect discontinuous or continuous reactions under changing physical
conditions. The main mineral assemblages encountered in these gneisses are orthopyroxene – cordierite – biotite – plagioclase
– perthite – quartz and garnet – orthopyroxene – cordierite – biotite – quartz – plagioclase – perthite ± sillimanite. Multiphase
reaction textures in conjunction with mineral chemical data in the KFMASH system indicate the following reactions:
Based on chemographic relationships and petrogenetic grids in the K2O–FeO–MgO–Al2O3–SiO2–H2O (KFMASH) system, a sequence of prograde (early stage), isothermal decompression (middle stage) and retrograde (late stage)
reactions (‘back reactions’ and hydration reactions) are inferred. Relatively lower P–T estimates (0.35 GPa/550–750 °C) obtained from the different geothermobarometers are attributed to late Fe–Mg re-equilibration
during cooling. Therefore, the convergence method has been applied to retrieve simultaneously the P–T conditions of the thermal peak of metamorphism. The near thermal peak condition of metamorphism estimated by the convergence
method are 850 °C/0.62 GPa. The P–T estimates define a retrograde trajectory with substantial decompression. 相似文献
997.
S. K. Sharma Manish Kumar Rohtash N. C. Gupta Saraswati Mohit Saxena T. K. Mandal 《Meteorology and Atmospheric Physics》2014,124(1-2):67-82
In the present paper, we have characterized the ambient ammonia over Delhi along with other trace gases (NH3, NO, NO2, SO2 and CO) and particulates (PM2.5 and PM10) measured during December 2011 to June 2012. The average mixing ratios of ambient NH3, NO, NO2, SO2 and CO were recorded as 21.2 ± 5.4, 19.5 ± 4.9, 17.4 ± 1.4, 1.7 ± 0.5 ppb and 1.6 ± 0.7 ppm, respectively, during winter, whereas the average mixing ratios of ambient NH3, NO, NO2, SO2 and CO were recorded as 20.8 ± 4.7, 21.7 ± 6.3, 16.8 ± 3.1, 2.2 ± 0.8 ppb and 1.8 ± 0.9 ppm, respectively, during summer. In the present case, non-significant seasonal and diurnal variations of NH3, NO, NO2, SO2 and CO were observed during both the seasons. The average monthly NH3/NH4 + ratios varied from 0.28 to 2.56 with an average value of 1.46 in winter. The higher NH3/NH4 + ratio (3.5) observed in summer indicates the abundance of NH3 in the atmosphere during summer. The higher fraction of particulate NH4 + observed in winter than summer attributes to the conversion of gaseous NH3 into NH4 +. The results emphasized that the traffic could be one of the significant sources of ambient NH3 at the urban site of Delhi as illustrated by positive correlations of NH3 with traffic-related pollutants (NO, NO2 and CO). Surface wind analysis and wind directions also support the roadside traffic and agricultural activities at the nearby area indicating possible major sources of ambient NH3 at the study site. 相似文献
998.
Assimilation of satellite-derived surface datasets has been explored in the study. Three types of surface data, namely sea level anomaly, sea surface temperature and sea surface salinity, have been used in various data assimilation experiments. The emphasis has been on the extra benefit arising out of the additional sea level assimilation and hence there are two parallel runs, in one of which sea level assimilation has been withheld. The model used is a state-of-the art ocean general circulation model (OGCM) and the assimilation method is the widely used singular evolutive extended Kalman filter (SEEK). Evaluation of the assimilation skill has been carried out by comparing the simulated depth of the 20°C isotherm with the same quantity measured by buoys and Argo floats. Simulated subsurface temperature and salinity profiles have also been compared with the same profiles measured by Argo floats. Finally, surface currents in the assimilation runs have been compared with currents measured by several off-equatorial buoys. Addition of sea level has been found to substantially improve the quality of simulation. An important feature that has been effectively simulated by the addition of sea level in the assimilation scheme is the near-surface temperature inversion (2-3°C) in the northern Bay of Bengal. 相似文献
999.
1000.
Coronal heating is one of the unresolved puzzles in solar physics from decades. In the present paper we have investigated the dynamics of vortices to apprehend coronal heating problem. A three dimensional (3d) model has been developed to study propagation of dispersive Alfvén waves (DAWs) in presence of ion acoustic waves which results in excitation of DAW and evolution of vortices. Taking ponderomotive nonlinearity into account, development of these vortices has been studied. There are observations of such vortices in the chromosphere, transition region and also in the lower solar corona. These structures may play an important role in transferring energy from lower solar atmosphere to corona and result in coronal heating. Nonlinear interaction of these waves is studied in view of recent simulation work and observations of giant magnetic tornadoes in solar corona and lower atmosphere of sun by solar dynamical observatory (SDO). 相似文献