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81.
Mingyue Lu Xinhao Wang Xintao Liu Min Chen Shuoben Bi Yadong Zhang Tengfei Lao 《Transactions in GIS》2021,25(1):25-43
Weather radar data play an important role in meteorological analysis and forecasting. In particular, web‐based real‐time 3D visualization will enable and enhance various meteorological applications by avoiding the dissemination of a large amount of data over the internet. Despite that, most existing studies are either limited to 2D or small‐scale data analytics due to methodological limitations. This article proposes a new framework to enable web‐based real‐time 3D visualization of large‐scale weather radar data using 3D tiles and WebGIS technology. The 3D tiles technology is an open specification for online streaming massive heterogeneous 3D geospatial datasets, which is designed to improve rendering performance and reduce memory consumption. First, the weather radar data from multiple single‐radar sites across a large coverage area are organized into a spliced grid data (i.e., weather radar composing data, WRCD). Next, the WRCD is converted into a widely used 3D tile data structure in four steps: data preprocessing, data indexing, data transformation, and 3D tile generation. Last, to validate the feasibility of the proposed strategy, a prototype, namely Meteo3D at https://202.195.237.252:82 , is implemented to accommodate the WRCD collected from all the weather radar sites over the whole of China. The results show that near real‐time and accurate visualization for the monitoring and early warning of strong convective weather can be achieved. 相似文献
82.
New evidence of sea‐level lowstands and paleoenvironment during MIS 6 and 4 in the Cantabrian coastal karst: the Cobiheru cave (North Iberia) 下载免费PDF全文
Daniel Ballesteros Laura Rodríguez‐Rodríguez Saúl González‐Lemos Santiago Giralt Diego Jaime Álvarez‐Lao Luna Adrados Montserrat Jiménez‐Sánchez 《地球表面变化过程与地形》2017,42(11):1704-1716
The geomorphological evolution of the Cobiheru Cave shows the influence of the non‐carbonate coastal mountain ranges on coastal karst evolution, as well as the temporal distribution of the cold‐adapted fauna sites in the Cantabrian Coast. Geomorphological observation and uranium/thorium (U/Th) dating lead to the construction of an evolution model. The model comprises two episodes of cave deposition occurring at c. 60–70 and 130–150 ka, linked to cold climate conditions, global sea‐level lowstands and the erosion of alluvial fans that covered the karst. Moreover, the comparison between the Cobiheru record and some raised beaches identified in previous studies sets the beginning of the sea‐level lowering in the Cantabrian Sea during the marine isotope stages (MIS) 5–4 transition. Two palaeoenvironments are inferred based on finding Equus ferus and Elona quimperiana. A wet deciduous forest would have developed on the emerged marine terrace of the Cobiheru Cave since at least the Middle Pleistocene, and an open landscape with scarce vegetation would have been present at c. 65 ka. The erosional event identified in the Cobiheru Cave helps to understand the temporal distribution of cold‐adapted mammals located in the Asturias region. The probable sites of cold‐adapted fauna developed in caves and alluvial fans would have disappeared after 65 ka. Therefore, palaeontological and palaeoclimate research based on cold‐adapted mammals suggests the occurrence of an hiatus in the palaeontological record prior to 50 ka. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
83.
本文对以往三十来年的工作进行了总结,在统计和分析大量的土工试验资料的基础上,从区域土质学的观点出发,研究了海南岛土类的成因、成份及各种土类的分布规律,探索了各类土的物理力学特性。文中所列的海南岛各种土类的物理力学试验研究成果,对今后海南岛的进一步开发有一定的参考价值。 相似文献
84.
Estimating submarine groundwater discharge at a subtropical river estuary along the Beibu Gulf,China
In certain regions,submarine groundwater discharge(SGD) into the ocean plays a significant role in coastal material fluxes and their biogeochemical cycle;therefore,the impact of SGD on the ecosystem cannot be ignored.In this study,SGD was estimated using naturally occurring radium isotopes(~(223)Ra and ~(224)Ra) in a subtropical estuary along the Beibu Gulf,China.The results showed that the Ra activities of submarine groundwater were approximately 10 times higher than those of surface water.By assuming a steady state and using an Ra mass balance model,the SGD flux in May 2018 was estimated to be 5.98×10~6 m~3/d and 3.60×10~6 m~3/d based on ~(224)Ra and ~(223)Ra,respectively.At the same time,the activities of Ra isotopes fluctuated within a tidal cycle;that is,a lower activity was observed at high tide and a higher activity was seen at low tide.Based on these variations,the average tidal pumping fluxes of SGD were 1.15×10~6 m~3/d and 2.44×10~6 m~3/d with ~(224)Ra and ~(223)Ra,respectively.Tidaldriven SGD accounts for 24%-51% of the total SGD.Therefore,tidal pumping is an important driving force of the SGD in the Dafengjiang River(DFJR) Estuary.Furthermore,the SGD of the DFJR Estuary in the coastal zone contributes significantly to the seawater composition of the Beibu Gulf and the material exchange between land and sea. 相似文献
85.
Microbial communities flourish at gas hydrate occurrences in ocean sediments. Studies are reported in this paper on the laboratory production, separation, characterization and hydrate catalysis of biosurfactants from cultures of the Bacillus subtilis bacterium associated with Gulf of Mexico gas-hydrate accumulations. The B. subtilis bacterium from ATCC 21332 species was cultured anaerobically with glucose as carbon-source to produce surfactin, one of the more potent surface active agents known. The surface-active agent was removed from the broth in foam created by bubbling inert gas through the mixture, and biosurfactant was then recovered from the collapsed-foam distilled water solution by acid precipitation and dichloromethane extraction. According to HPLC spectra, five surfactin isomers were identified in the sample of laboratory-generated biosurfactant. Recovered surfactin was then used to perform gas-hydrate formation studies in porous media saturated with the surfactin-water solution. Gas-hydrate induction time and formation rate determinations showed that the anaerobically-produced biosurfactants catalyzed hydrate formation markedly. The tests suggest prolific surfactin production by the B. subtilis bacterium and of other species under prevailing anaerobic conditions around seafloor gas hydrates that promotes hydrate formation and the propensity of the bioproduct to be dispersed in the porous media by natural gas vents. 相似文献
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