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411.
Coastal reclamation has been carried out along the coastal areas near Shenzhen, China in a large scale since 1980s by dumping
fill materials over the marine mud at the sea bottom. Usually the area to be reclaimed is drained first and some of the mud
is air-dried for a few weeks before it is buried by fill. After reclamation, the terrestrial groundwater, which is relatively
acidic and with high dissolved oxygen, gradually displaces the seawater, which is alkaline with high salinity. The changes
in the burial conditions of mud and the properties of the pore water in the mud may induce the release of some heavy metals
into the mud. Field survey confirms that the pH and salinity of the groundwater in the reclamation site are much lower than
the seawater. Chemical analyses of mud and groundwater samples collected from the reclamation sites reclaimed in different
years indicate that most of the heavy metals in the mud decrease gradually with time, but the heavy metals in the groundwater
are increased. The release of heavy metals into pore water due to reactivation of heavy metals in the mud is of environmental
concern. To understand why some of the heavy metals can be released from the mud more easily than others, a sequential extraction
method was used to study the operationally determined chemical forms of five heavy metals (Cu, Ni, Pb, Zn, and Cd) in the
mud samples. Heavy metals can be presented in five chemical forms: exchangeable, carbonate, Fe–Mn oxide, organic, and residual.
Ni and Pb were mainly associated with the Fe–Mn oxide fraction and carbonate fraction; Zn was mainly associated with organic
fraction and Fe–Mn oxide fraction, while Cu and Cd were associated with organic fraction and carbonate fraction, respectively.
If the residual fraction can be considered as an inert phase of the metal that cannot be mobilized, it is the other four forms
of heavy metal that cause the noticeable changes in the concentration of heavy metals in the mud. On the basis of the speciation
of heavy metals, the mobility of metals have the following order: Pb (36.63%) > Cu (31.11%) > Zn (20.49%) > Ni (18.37%) > Cd
(13.46%). The measured metal mobility fits reasonably well with the degree of concentration reduction of the metals with time
of burial observed in the reclamation site. 相似文献
412.
澳大利亚西澳州2004-2005年度矿产勘探综述 总被引:1,自引:0,他引:1
介绍了澳大利亚西澳州2004—2005年度金、镍、铁、钛、锆、金刚石矿床的勘探情况和取得的找矿成果。简述了2004—2005年度西澳州矿产勘探(包括石油勘探)消费支出、不同矿产品所占勘探支出的份额、钻探、矿山土地复垦及环境保护的情况。 相似文献
413.
在满足土地复垦用途要求的前提下,设计场地平整参数,提高平整土方量计算精度。研究方法:采用最小二乘法。研究结果:用最小二乘法设计场地平整参数的法方程、土方量计算公式及其精度分析公式。研究结论:用最小二乘法进行场地平整参数设计及土方量计算,适用范围广,计算精度高,而且易于计算机实现。 相似文献
414.
415.
叶舜赞 《中国地理科学(英文版)》1998,8(1):12-24
THELANDRESOURCEANDLANDUSEOFHONGKONG①YeShunzan(叶舜赞)InstituteofGeography,theChineseAcademyofSciences,Beijing100101,P.R.China(Re... 相似文献
416.
The erosion of hillslopes reclaimed following the surface-mining of coal is an important geomorphologic concern. However, progress in the design of post-mining topography and its hydrologic response has been hampered by the paucity of research focusing on the propensity of rill formation on these disturbed surfaces. This investigation is intended to partially rectify this situation through the development of regression equations for the prediction of rill frequency and magnitude based upon site characteristics. Rill width can be estimated using soil bulk density, hillslope age, and hillslope length with a standard error of 0.152 log10 units at this location. Rill depth can be estimated using soil shear strength, hillslope length, and hillslope age with a standard error of 0.114 log10 units. Rill length can be estimated using hillslope length, percent silt in the soil, hillslope age, Bouyoucos Clay Ratio, and soil bulk density with a standard error of 3.515 m. Rill frequency can be estimated using soil bulk density, Bouyoucos Clay Ratio, soil compaction, soil reaction (pH), and hillslope age with a standard error of 0.241 rills/m. The cross-product of rill width times depth can be estimated using soil shear strength, hillslope length, hillslope age, and soil bulk density with a standard error of 0.260 log10 units. These results must be tested further under various environmental conditions. Nevertheless, prediction of rill formation seems to be a problem capable of solution. 相似文献
417.
Terrence J. Toy 《地球表面变化过程与地形》1989,14(4):289-302
Comparative erosion rates provide a rational basis for evaluating reclamation success because the work performed by erosion processes is a function of both forces and resistances operating on a surface. Sheetwash erosion data collected by the LEMI technique over several years at the Dave Johnston Mine in east-central Wyoming show that, based upon average values, there is generally little difference between the erosion rates of natural and reclaimed hillslopes at this locale. Therefore, it is permissible to infer that the reclamation programme has been successful from a geomorphic perspective. However, there is considerable variation in erosion rates about the average for individual hillslopes in both the natural and reclaimed groups. Examination of these data by hillslope element and segment show that, based upon average values, the concave elements of natural and reclaimed hillslopes experience the highest rate of sheetwash erosion. Again, however, there is considerable variation about the average and considerable erosion can occur in any element or segment of particular hillslopes. Lastly, there are seasonal oscillations of hillslope surface elevation with frost-heaving prevalent during the late autumn to early spring months and erosion prevalent during the late spring to early autumn months. 相似文献
418.
遥感技术在古丹阳湖演变研究中的应用 总被引:1,自引:0,他引:1
运用适合于湖泊演变研究的遥感图像处理方法,从遥感图像的色调、结构、纹理入手,探讨了不同湖泊演变类型的遥感影像特征和差异性并结合多种历史图件与资料,阐述了古丹阳湖演变的规律,其结果对研究我国东部平原地区湖泊的形成及演变规律有积极意义。 相似文献
419.
420.