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991.
Maarten Wynants Linus Munishi Kelvin Mtei Samuel Bodé Aloyce Patrick Alex Taylor David Gilvear Patrick Ndakidemi William H. Blake Pascal Boeckx 《地球表面变化过程与地形》2021,46(15):3096-3111
Water bodies in Tanzania are experiencing increased siltation, which is threatening water quality, ecosystem health, and livelihood security in the region. This phenomenon is caused by increasing rates of upstream soil erosion and downstream sediment transport. However, a lack of knowledge on the contributions from different catchment zones, land-use types, and dominant erosion processes, to the transported sediment is undermining the mitigation of soil degradation at the source of the problem. In this context, complementary sediment source tracing techniques were applied in three Tanzanian river systems to further the understanding of the complex dynamics of soil erosion and sediment transport in the region. Analysis of the geochemical and biochemical fingerprints revealed a highly complex and variable soil system that could be grouped in distinct classes. These soil classes were unmixed against riverine sediment fingerprints using the Bayesian MixSIAR model, yielding proportionate source contributions for each catchment. This sediment source tracing indicated that hillslope erosion on the open rangelands and maize croplands in the mid-zone contributed over 75% of the transported sediment load in all three river systems during the sampling time-period. By integrating geochemical and biochemical fingerprints in sediment source tracing techniques, this study demonstrated links between land use, soil erosion and downstream sediment transport in Tanzania. This evidence can guide land managers in designing targeted interventions that safeguard both soil health and water quality. 相似文献
992.
Maarten Wynants Aloyce Patrick Linus Munishi Kelvin Mtei Samuel Bodé Alex Taylor Geoffrey Millward Neil Roberts David Gilvear Patrick Ndakidemi Pascal Boeckx William H. Blake 《地球表面变化过程与地形》2021,46(15):3112-3126
Soil resources in parts of Tanzania are rapidly being depleted by increased rates of soil erosion and downstream sediment transport, threatening ecosystem health, water and livelihood security in the region. However, incomplete understanding to what effect the dynamics of soil erosion and sediment transport are responding to land-use changes and climatic variability are hindering the actions needed to future-proof Tanzanian land-use practices. Complementary environmental diagnostic tools were applied to reconstruct the rates and sources of sedimentation over time in three Tanzanian river systems that have experienced changing land use and climatic conditions. Detailed historical analysis of sediment deposits revealed drastic changes in sediment yield and source contributions. Quantitative sedimentation reconstruction using radionuclide dating showed a 20-fold increase in sediment yield over the past 120 years. The observed dramatic increase in sediment yield is most likely driven by increasing land-use pressures. Deforestation, cropland expansion and increasing grazing pressures resulted into accelerating rates of sheet erosion. A regime shift after years of progressive soil degradation and convergence of surface flows resulted into a highly incised landscape, where high amounts of eroded soil from throughout the catchment are rapidly transported downstream by strongly connected ephemeral drainage networks. By integrating complementary spatial and temporal evidence bases, this study demonstrated links between land-use change, increased soil erosion and downstream sedimentation. Such evidence can guide stakeholders and policy makers in the design of targeted management interventions to safeguard future soil health and water quality. 相似文献
993.
The interaction between the land surface and the atmosphere is a crucial driver of atmospheric processes. Soil moisture and precipitation are key components in this feedback. Both variables are intertwined in a cycle, that is, the soil moisture – precipitation feedback for which involved processes and interactions are still discussed. In this study the soil moisture – precipitation feedback is compared for the sempiternal humid Ammer catchment in Southern Germany and for the semiarid to subhumid Sissili catchment in West Africa during the warm season, using precipitation datasets from the Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS), from the German Weather Service (REGNIE) and simulation datasets from the Weather Research and Forecasting (WRF) model and the hydrologically enhanced WRF-Hydro model. WRF and WRF-Hydro differ by their representation of terrestrial water flow. With this setup we want to investigate the strength, sign and variables involved in the soil moisture – precipitation feedback for these two regions. The normalized model spread between the two simulation results shows linkages between precipitation variability and diagnostic variables surface fluxes, moisture flux convergence above the surface and convective available potential energy in both study regions. The soil moisture – precipitation feedback is evaluated with a classification of soil moisture spatial heterogeneity based on the strength of the soil moisture gradients. This allows us to assess the impact of soil moisture anomalies on surface fluxes, moisture flux convergence, convective available potential energy and precipitation. In both regions the amount of precipitation generally increases with soil moisture spatial heterogeneity. For the Ammer region the soil moisture – precipitation feedback has a weak negative sign with more rain near drier patches while it has a positive signal for the Sissili region with more rain over wetter patches. At least for the observed moderate soil moisture values and the spatial scale of the Ammer region, the spatial variability of soil moisture is more important for surface-atmosphere interactions than the actual soil moisture content. Overall, we found that soil moisture heterogeneity can greatly affect the soil moisture – precipitation feedback. 相似文献
994.
江苏省耕地转化为建设用地的经济学分析 总被引:6,自引:1,他引:5
江苏省建设占用耕地现象越来越严重,耕地保护面临着巨大的困难。该文利用经济学的均衡分析方法、制度分析方法及非线性动力学方法,初步探讨了耕地转化为建设用地的内在机制。边际产出的差距是耕地转化为建设用地的直接动力,目前存在的一些制度和政策降低了耕地转化为建设用地的交易成本,外资的涌入、经济的快速发展消除了资本的限制。根据其转化的内在机制提出如下建议:1)把耕地减少上升到社会问题的高度来认识;2)改变当前的征地方式;3)把耕地保护纳入政绩考核的范围;4)提高农业的产出。 相似文献
995.
区域土地利用变化信息图谱模型研究 总被引:8,自引:0,他引:8
信息图谱为区域土地利用变化提供了一种谱系化、定量化与定位化相结合的研究方法,借助信息图谱模型探讨区域土地利用变化及其时空过程的多维性与复杂性,为土地利用变化的驱动力诊断、机理模型与预测模型的构建提供科学依据。选取吉林省长岭县为研究区,在遥感与GIS技术支持下,以土地利用时空演变模式、空间扩展过程、景观特征等为框架,建立土地利用变化信息图谱模型,对图谱方法在土地利用变化研究中的应用进行实证分析。 相似文献
996.
区域土地资源配置与社会经济发展 总被引:8,自引:3,他引:5
文章在阐述土地资源配置与区域社会经济发展的辩证关系的基础上,分别从土地资源供给约束、资源禀赋和利用结构方面探讨了土地资源配置对区域社会经济发展的影响与制约,并对实现十六大提出的全面建设小康社会目标,从土地资源配置角度提出对策与建议。 相似文献
997.
山东耕地动态变化与粮食总产量相关分析 总被引:3,自引:0,他引:3
文章收集1949—2000年山东省耕地、人口、粮食等资料,定量定性分析耕地的数量、质量变化与粮食产量的相关性。用SPSS中的一元线性回归法预测人口变化趋势,对粮食总产量与其影响因素进行相关分析,发现粮食单产对粮食总产量影响最大,同时耕地质量的逐年下降是粮食增产是重要的制约因素。提出外延式和内涵式开发耕地资源是增产粮食的有效途径,为解决粮食安全问题实现耕地的可持续发展提供科学决策依据。 相似文献
998.
农地城市流转决策优化研究 总被引:15,自引:1,他引:14
农地保护与城市发展被认为是一对矛盾。农地城市流转决策应协调好二者的关系,以实现土地的可持续利用。而现行决策的片面性从某种程度上助长了农地的盲目流失,直接影响到我国土地资源的后续利用、粮食安全、生态环境等。文章从可持续利用的角度,通过对农地城市流转的选择价值和外部性的分析及评价,优化了农地城市流转决策。 相似文献
999.
Both land use/land cover change (LUCC) and the effects of nutrients cycles on terrestrial ecosystems and biodiversity are key environmental problems in the 21st century (Yang etal., 2002; Li, 1996; Bai and Bai, 1998). Land cover change is the accumulated result of land use, which includes three types, i.e., deterioration, transition and amelioration of land cover (Cai, 2001). The nutrient cycle is the main functional process to maintain stability and production of an ecosystem. Land cover … 相似文献
1000.
During the last decade of the 20th century, extensive conversion in agricultural land use took place in Northeast China. The goal of this study is to ascertain its spatial distribution and regional differentiation, determine its causes, and analyze its environmental impact, Especially we attempt to elucidate how institutional constraints have facilitated the change at a time of agrarian restructuring when newly emerging free market was hybridized with the former planned economy. Information on six categories of land use was mapped from interpretation of Landsat TM images recorded in 1990,1995 and 2000. Most of land use changes took place during the first half of the decade, coinciding with abrupt and chaotic changes in government directives. Farmland was changed mainly to woodland,water body and built-up areas while woodland and grassland were converted chiefly to farmland.Spatially, the change from farmland to woodland was restricted to the west of the study area. The change from grassland to farmland took place in the grazing and farming interlocked west. These chaotic and occasionally conflicting changes were largely caused by lack of stability and consistency in agricultural land use policies promulgated. They have exerted adverse impacts on the local environment, including land degradation, increased flooding, and modified climate regime. 相似文献