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41.
准确刻画精细化尺度下的城市房租空间格局,对于研究城市居住行为、提高城市规划合理性十分重要。文章提出了一种基于互联网房租数据作为可靠数据源的城市房租空间格局制图方法。以深圳市作为研究区,通过广泛采集开放平台中用户发布的租房信息,绘制社区行政区尺度的房租空间分布图。房租空间制图涉及到对于没有样本数据区域平均房租的评估,因此,选取一系列与房租相关的房产属性、房屋区位及配套设施的评价指标,采用前馈神经网络技术构建评估模型。以2015年深圳市的住宅租赁市场作为研究对象,通过对结果的分析,以及与权威部门发布的统计数据进行比较,表明此方法能够有效地绘制社区尺度下城市房租的空间分布,模型预测结果的误差(%RMSE)为13.87%。所使用的互联网房租数据、POIs数据及前馈神经网络的建模工具均是开源的,而且所提出的方法论具有普适性,能够应用于其他研究区的房租空间格局制图,具有实践意义。 相似文献
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Peter R. Robichaud Sarah A. Lewis Joseph W. Wagenbrenner Robert E. Brown Fredrick B. Pierson 《地球表面变化过程与地形》2020,45(3):771-782
Large wildfires can have profound and lasting impacts not only from direct consumption of vegetation but also longer-term effects such as persistent soil erosion. The 2002 Hayman Fire burned in one of the watersheds supplying water to the Denver metropolitan area; thus there was concern regarding hillslope erosion and sedimentation in the reservoirs. The efficacy of various treatments for reducing erosion was tested, including hand scarification on contour, agricultural straw mulch, wood mulch, burned controls and unburned reference plots. Simulated rill erosion experiments were used both immediately after the fire and again 10 years post fire. To better understand untreated recovery, the same experiments were applied to control plots in post-fire years 1, 2, 3 and 4, and in unburned reference plots in years 4 and 10. Results indicate that control and scarified plots produced significantly greater sediment flux rates – 1.9 and 2.8 g s−1 respectively – than the straw and wood mulch treatments – 0.9 and 1.1 g s−1 – immediately after the fire. Mulch treatments reduced runoff rate, runoff velocity, and sediment concentration and flux rate. The straw mulch cover was no longer present, whereas the wood mulch was still there in year 10. Vegetation regrowth was slow and mulch treatments provided effective cover to reduce sediment right after the fire. In post-fire year 10, there were no significant differences in sediment flux rates across treatments; it is notable, however, that the wood mulch treatment (0.09 g s−1) most closely approached the unburned condition (0.07 g s−1). The burned control plots had high sediment flux rates until post-fire year 3, when flux rates significantly decreased and were statistically no longer higher than the unburned levels from year 4 and 10. These results will inform managers of the longer-term post-fire sediment delivery rates and of the ability of post-fire emergency hillslope treatments to mitigate erosion rates. Published 2019. This article is a U.S. Government work and is in the public domain in the USA. 相似文献
44.
An evacuation trigger is a point on the landscape that, once crossed by a wildfire, triggers an evacuation for a community.
The Wildland-Urban Interface Evacuation (WUIVAC) model can be used to create evacuation trigger buffers around a community
using fuels, weather, and topographic inputs. A strategic, community-scale application of WUIVAC for the town of Julian, California
was investigated. Eight years of wind measurements were used to determine the worst-case (strongest) winds in 16 directions.
Surface fire rate of spread was used to calculate evacuation trigger buffers for the communities of Julian and nearby Whispering
Pines, and for three potential evacuation routes. Multiple trigger buffers were combined to create fire planning areas, and
trigger buffers that predict the closure of all evacuation routes were explored. WUIVAC trigger buffers offer several potential
benefits for strategic evacuation planning, including determination of when to evacuate and locating potential evacuation
routes. 相似文献
45.
A pollen record from Lake Xere Wapo, southeast New Caledonia, is the longest continuous terrestrial record to be recovered from the tropical southwest Pacific and reveals a series of millennial scale changes in vegetation over the last 130,000 yr. A comparison of the Lake Xere Wapo record with the key northeast Australian record of Lynch's Crater reveals regional patterns of change. From 120,000 to 50,000 yr ago the vegetation around Lake Xere Wapo alternated between rainforest and maquis with fire an important disturbance factor. In the last 50,000 yr fire is almost absent from the record and the vegetation assumes a character unprecedented in the preceding 100,000 yr, dominated by Dacrydium and Podocarpus pollen. The most compelling aspect of the comparison with Lynch's Crater is that the much-discussed Araucaria decline at around 45,000 yr ago in northern Queensland is matched by a similar decline in the Lake Xere Wapo record. 相似文献
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Increases in runoff and erosion after wildfires are often attributed to the development of hydrophobic soils. The potential for increased overland flow depends on the spatial contiguity of the hydrophobicity as well as its overall strength, but there is limited information on the spatial variability of soil hydrophobicity. We conducted spatially intensive hydrophobicity measurements in 225 m2 and 1 m2 plots in forested areas of Montana and Colorado burned at moderate to high severity, and in unburned control plots. Both the burned and unburned 225 m2 plots contained 10–23 hydrophobic soil patches in which hydrophobicity was strongest at the surface and declined rapidly with depth. The hydrophobic patches were closer together and up to 3 times larger in the burned plots. Consequently, 19% to 76% of the burned plots were hydrophobic compared to just 11% of the unburned plots. In five of the six burned plots, the patches were not laterally connected, suggesting that in most cases Hortonian overland flow generated from hydrophobic patches will infiltrate near its point of origin. The 1 m2 plots were smaller than most of the hydrophobic patches, so they did not capture the spatial characteristics of soil hydrophobicity. Characterization of the spatial variability of soil hydrophobicity should be based on measurements conducted at 1 m intervals across areas of > 100 m2. Due to the patchiness of soil hydrophobicity at the 100 to 101 meter scale, overland flow measurements in small ( 1 m2) plots may overestimate the magnitude and variability of runoff from burned catchments. 相似文献
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Qingmin Meng Ross K. Meentemeyer 《International Journal of Applied Earth Observation and Geoinformation》2011
Most of fire severity studies use field measures of composite burn index (CBI) to represent forest fire severity and fit the relationships between CBI and Landsat imagery derived differenced normalized burn ratio (dNBR) to predict and map fire severity at unsampled locations. However, less attention has been paid on the multi-strata forest fire severity, which represents fire activities and ecological responses at different forest layers. In this study, using field measured fire severity across five forest strata of dominant tree, intermediate-sized tree, shrub, herb, substrate layers, and the aggregated measure of CBI as response variables, we fit statistical models with predictors of Landsat TM bands, Landsat derived NBR or dNBR, image differencing, and image ratioing data. We model multi-strata forest fire in the historical recorded largest wildfire in California, the Big Sur Basin Complex fire. We explore the potential contributions of the post-fire Landsat bands, image differencing, image ratioing to fire severity modeling and compare with the widely used NBR and dNBR. Models using combinations of post-fire Landsat bands perform much better than NBR, dNBR, image differencing, and image ratioing. We predict and map multi-strata forest fire severity across the whole Big Sur fire areas, and find that the overall measure CBI is not optimal to represent multi-strata forest fire severity. 相似文献
50.
Google earth是一款用于地物的3维浏览、坐标查询、地标制作、线路漫游等功能的虚拟地球仪软件。利用Google earth对遵化市D级GPS控制点信息进行导入与地标生成,可以实时动态地管理和利用控制点信息,极大地方便了控制点在测绘领域的应用。 相似文献