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171.
172.
In recent years,we have entered the so-called Fourth Paradigm with the regular production of huge amount of observational data.Big data is often characterized by the three‘V's:Volume of data,Variety and Velocity.The concept of big data can potentially address some existing issues in areas of geoscience and geoengineering.Large-scale,comprehensive,multidirectional and multifield geotechnical monitoring is becoming a reality in the very near future. 相似文献
173.
Mathematical Geosciences - The presence of outliers in geochemical data can impact the accuracy of grade models and influence the interpretation of mine assay data. Removal of outliers is therefore... 相似文献
174.
Mathematical Geosciences - In surface mining, assay measurements taken from production drilling often provide useful information that enables initially inaccurate surfaces (for example,... 相似文献
175.
A parallel numerical finite difference model, employing the self-implicit method, for coupled heat and moisture transfer in unsaturated soil is presented. The model is programmed in Occam and executed on a parallel computing network of transputers. An assessment of the model was achieved via the simulation of a laboratory experiment. A very good correlation between experimental and numerical results was obtained. Comparison of results with those obtained from a parallel explicit method is also illustrated showing no significant difference. The computational time employing the new method was, however, found to be half of that obtained using the explicit method. The computational efficiency of the approach was also found to be very high. © 1997 John Wiley & Sons, Ltd. 相似文献
176.
Seasonal changes in imposex and tissue burden of butyltin compounds in Thais clavigera populations along the coastal area of Mirs Bay, China 总被引:1,自引:0,他引:1
We assessed the current status of tributyltin (TBT) contamination of Thais clavigera (Gastropoda) along the coastal area of Mirs Bay, China for the first time. The snail samples were collected from 10 different sites in the summer (June) and winter (December) of 2006, respectively. They were analyzed for imposex status, i.e. relative penis size index (RPSI) and vas deferens sequence index (VDSI), followed by quantification of butyltins in their tissues. Most of the collected females suffered from imposex, but the level of butyltin contamination varied with the distance from Yantian Port, which is currently the fourth busiest container port in the world. The tissue concentration of TBT varied with season. For a particular site, the winter samples in general contained much higher concentration of TBT than the summer samples. RPSI, VDSI and organotin concentrations were higher in T. clavigera collected from sites closer to the Port, such as the Seafood Street and Kat O. Both RPSI and VDSI were positively correlated with the tissue burden of tributyltin. VDSI exhibited little seasonal variability, whereas RPSI showed marked seasonal variability, with lower values in the summer samples. The current results will serve as an important reference for long-term monitoring of butyltin contamination in this area. 相似文献
177.
A series of centrifuge tests were performed to investigate the response of a free-head monopile due to cyclic lateral loading in normally consolidated clay. By linking the maximum reaction-force point of the final cycles in all tests with various amplitudes, a postcyclic reaction-force curve is obtained, which can be used to assess the postcyclic remolded lateral stiffness. To numerically analyze the tests, a strength degradation model of the clay is calibrated by the T-bar cyclic test. However, this model is T-bar-dependent, which is unable to capture the degrading behavior of the monopile stiffness. Thus, a modification approach is proposed based on the upper bound theory, and the modified model is further combined with finite element analysis to simulate the cyclic behavior of the model pile. The simulation results show similar degrading trend and consistent postcyclic remolded lateral stiffness with the model tests. This further demonstrates that the remolded lateral stiffness mainly depends on the soil remolded strength, which is one of the parameters calibrated by the T-bar tests. Based on this finding, a simplified numerical analysis is proposed, which can predict the postcyclic reaction-force curve by performing one monotonic loading instead of modeling the whole process of cyclic loading. 相似文献
178.
A numerical stochastic model is developed for the upcrossing rate across a specified threshold concentration. The model assumes that the concentration time series at a given spatial point within a dispersing plume can be approximated as a first-order Markovian process designed to be consistent with a given time-invariant concentration probability density function (pdf). The model requires only the specification of a concentration pdf with a given mean and variance and a concentration fluctuation integral time scale. Predicted upcrossing rates are compared with atmospheric plume concentration data obtained from a point source near the ground. For this data set, a log-normal pdf is found to give better estimates of the threshold crossing rate than a gamma pdf. 相似文献
179.
180.
Correlations between gastropod shell dissolution and water chemical properties in a tropical estuary 总被引:1,自引:0,他引:1
Although poorly reported in the scientific literature, acidic waters characterize many South East Asian estuaries. The observation of shell dissolution in a typically marine gastropod whelk (Thais) prompted investigation into determining relationships between shell properties of this whelk and the water chemistry (including pH) of the Sungai Brunei estuary (Borneo) in which it occurs. Shell weight, shell length and topographical shell features were determined for populations of Thais gradata distributed along a gradient of pH and salinity ranging between 5.78 and 8.3 pH units, and 3.58 and 31.2psu. Shell weight varied independently of the co-varying acidity, salinity and calcium levels experienced. In contrast, shell length and a semi-quantitative variable based on shell sculpturing (shell erosion rank, SER) were significantly correlated with these water chemistry variables. This study brings attention to the potential use of estuarine organisms and systems in investigating current marine acidification questions. 相似文献