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991.
Geo-hazards with characteristics and prevention measures along the coastal regions of China 总被引:1,自引:0,他引:1
China has more than 18,000 km long coastline. Along the coastline, there are various configurations of topography, geomorphology,
and geology condition. In the coastal regions, geological disasters, including seawater intrusion, coast scouring, land subsidence,
karst collapse, soil erosion, collapse-landslide-debris flow (CLDF), and human activity-induced disasters, occur frequently.
All of these disasters have their own forming causes, characteristics, and distribution regions. Seawater intrusion and coast
scouring only occur in the coastal regions while the others occur in both coastal regions and in-land regions. Land subsidence
occurring in the coastal region is of larger scale and entails greater economic loss than that occurring in the in-land region.
For the other disasters, although the scale of disaster in the coastal regions is smaller than that happened in the in-land
regions, the economic loss in the former case is greater than that in the latter. This is because populations are dense and
economy is developed along the coastal regions of China. To mitigate the disasters and reduce the economic loss, countermeasures
are discussed. 相似文献
992.
Natural and anthropogenic influences in the northeastern coast of the Nile delta,Egypt 总被引:4,自引:0,他引:4
Landsat enhanced thematic mapper imagery (ETM) of 2002 and aerial photography of 1955, combined with published charts and
field observations were used to interpret coastal changes in the zone between Kitchener drain and Damietta spit in the northeastern
Nile delta, previously recognized as a vulnerable zone to the effects of any sea level rise resulting from global warming.
The interpretation resulted in recognition of several changes in nine identified geomorphological land types: beach and coastal
flat, coastal dunes, agricultural deltaic land, sabkhas, fish farms, Manzala lagoon, saltpans, marshes and urban centers.
Reclamation of vast areas of the coastal dunes and of Manzala lagoon added about 420 km2 to the agricultural deltaic land.
About 48 km2 of backshore flats, marshes, salt pans and Manzala lagoon have been converted to productive fish farms. The main
urban centers have expanded; nearly 12.1 km2 have been added to their areas, and new urban centers (Damietta harbor and the New Damietta city) with total area reach of
~35.3 km2 have been constructed at the expense of vast areas of Manzala lagoon, coastal dunes, and backshore flats. As a consequence
of human activities, the size of Manzala lagoon has been reduced to more than 65%. Shoreline changes have been determined
from beach profile survey (1990–2000), and comparison of 1955 aerial photographs and ETM satellite image of 2002 reveal alongshore
patterns of erosion versus accretion. The short-term rate of shoreline retreat (1990–2000) has increased in the downdrift
side of Damietta harbor (≃14 m/year), whereas areas of accretion exist within the embayment of Gamasa and in the shadow of
Ras El Bar detached breakwaters system, with a maximum shoreline advance of ~15 m/year. A sandy spit, 12 km long, has developed
southeast of Damietta promontory. These erosion/accretion patterns denote the natural processes of wave-induced longshore
currents and sediment transport, in addition, the impact of man-made coastal protection structures. 相似文献
993.
Spatial and seasonal variation of salt ions under the influence of halophytes,in a coastal flat in eastern China 总被引:1,自引:0,他引:1
Yanyou Wu Rongcheng Liu Yuguo Zhao Pingping Li Congqiang Liu 《Environmental Geology》2009,57(7):1501-1508
The high salinity of coastal saline field is a key factor limiting the reclamation. Halophytes have been utilized in the reclamation
of saline land. The study area is in Yancheng, China. An analysis of the concentrations of Rb, Cs, Sr, and Ba, the ratio of
Rb/Cs, and Sr/Ba in soils in autumn shows that the soil of this study area has great homogeneity. Artemisia halodendron, Gossypium hirsutum, and Sesbania cannabina were selected as the reclamation plants in the present study. In order to know the spatial-temporal distribution of soil
salinity, the influence of plant-specific vegetation, and the difference of desalination among these halophytes in coastal
flat, the authors analyze the soil-layers and seasonal variation in salt ions. Sodium chloride was accumulated in 0–5 cm topsoil
with no vegetation during the winter and spring. The effect of desalinization of halophytes is significant. Of the three plant
species, Sesbania cannabina has the greatest desalinization. The difference of ions composition of soils covered with various plant species is significant.
It can be concluded that halophytes have better amelioration of coastal soil salinity. Special attention should be paid to
the selection of plant species and measures to plant and cultivate crops in the reclamation of saline land. 相似文献
994.
995.
Water extractions in coastal areas have to deal with salt water intrusion and lowering of hydraulic heads in valuable ecosystems.
Therefore, sustainable management of fresh water resources in these areas is crucial. This is illustrated here with two water
extractions in the western Belgian coastal plain which extract groundwater from a phreatic dune aquifer. One water extraction
faced problems with salt water intrusion, while lowering of hydraulic heads was an issue for both. To remedy the salt water
intrusion, it was found that decreasing the extraction rate was the only solution. To offset this and to increase hydraulic
heads around both extractions, it was decided to artificially recharge the aquifer of the second extraction with tertiary
treated wastewater. By taking these interventions, the combined production capacity of the water extractions was increased
with 56% whereas 27% less water was extracted from the dune aquifer itself. Extraction history and the effects of interventions
are illustrated for both water extractions with water quality data and fresh water head observations. A more detailed insight
in groundwater flow and fresh–salt water distribution in the aquifer is provided by simulating the evolution of the water
extractions with a 3D density dependent groundwater flow model. 相似文献
996.
Concentrations of Fe, Mn, Zn, Cu, Pb, Ni, and Cd were measured in several species and genera of Recent benthic foraminifera
from three coastal lagoons, namely Abu-Shaar, Umm al-Huwaytat, and Marsa Shuni lagoons located along the Egyptian Red Sea
coast. Spatially significant differences in the metal concentrations of benthic foraminifera were recorded among different
sites. However, some foraminiferal species display deformation in their coiling, general shape of chambers and the apertures.
Abu-Shaar and Umm al-Huwaytat lagoons are virtually influenced by anthropogenic activities while Marsa Shuni lagoon is affected
by natural inputs. Benthic foraminifer shows high concentrations of Fe and Mn, especially in Umm al-Huwaytat lagoon. Foraminiferal
black tests support this result and reflect selectivity for iron absorption. Among the metals analyzed, Cd, Pb, and Cu showed
significant high concentrations in benthic foraminifera at the study areas. The anthropogenic activities and natural inputs
are responsible for the abnormalities in benthic foraminifera. Therefore, benthic foraminifera can be used as a good indicator
of the environmental changes. 相似文献
997.
以日照市山海天地区为典型调查区域,从调查本身的可操作性以及数据的可得性等角度出发,野外采集土壤、地表水、地下水样品,利用3s技术、地质统计学等先进技术方法进行试验分析和评价,探讨其水土资源质量现状,揭示该区湿地功能面临的主要威胁。结果表明:该区段水质状况堪忧,地表水典型污染物质超标严重,地下水水质综合评价较差。从研究区土壤中的Pb、Zn、As、Hg、Cd、Cr等典型污染物质的综合评价来看,该区域土壤环境质量总体优良;从土壤中典型污染物质的Kriging空间插值分析来看,除cd空间分布规律不甚明显外,其余均表现出一定的空间结构特征。 相似文献
998.
999.
新围涂区土壤脱盐与地下水淡化预测分析 总被引:1,自引:0,他引:1
以浙江玉环县漩门二期水库蓄淡工程背景,从土壤盐分统计预报的基本方法——数理统计法出发来预测涂区土壤的脱盐速度,建立了对数函数数学模型并进行了模型的检验与讨论,得出适用于该滩涂湿地涂区的土壤脱盐量公式并进行了预测计算。在此基础上,采用相类似的对数函数拟合的方法对涂区土壤浅层地下水淡化速度进行了预测分析。 相似文献
1000.
资源型城市土地利用变化与湿地生态安全响应--以黑龙江省大庆市为例 总被引:11,自引:1,他引:10
黑龙江省大庆市作为典型的资源型城市(以石油资源、草场资源和耕地资源发展起来),是人地关系作用最强烈的区域之一,也是土地利用发生急剧变化且具有特色的区域.揭示本区域土地利用的时空变化特征和变化规律,探讨土地利用变化引发的生态安全问题,对于资源型城市生态环境改善,产业结构调整及实现资源型城市可持续发展尤为重要.为此,本研究基于大庆市1978、1988、1992、1996和2001年5个时段的MSS和TM影像,获取20a来不同时期的土地利用信息.以GIS技术为数据集成分析平台,计算湿地景观格局指数和各湿地景观类型的时空转移过程,以期从景观格局的角度定量刻画区域湿地景观过程对土地利用变化的响应和由此产生的湿地生态安全威胁.结果表明,区域内耕地不断增加,建设用地的扩大,以及湿地盐碱化和草甸化过程,是湿地减少的重要原因之一;土地利用造成的湿地景观分割、景观破碎和景观迅速减少,对生物多样性安全、水资源安全和人类健康安全等产生威胁;因而,应根据人类与自然共生原理,对不同湿地进行景观生态的分析、评价、规划和设计,逐步恢复原有的自然湿地景观,使其发挥多种湿地功能. 相似文献