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971.
This article derives the closed‐form solutions for estimating the vertical surface displacements of cross‐anisotropic media due to various loading types of batter piles. The loading types include an embedded point load for an end‐bearing pile, uniform skin friction, and linear variation of skin friction for a friction pile. The planes of cross‐anisotropy are assumed to be parallel to the horizontal ground surface. The proposed solutions are never mentioned in literature and can be developed from Wang and Liao's solutions for a horizontal and vertical point load embedded in the cross‐anisotropic half‐space. The present solutions are identical with Wang's solutions when batter angle equals to 0°. In addition, the solutions indicate that the surface displacements in cross‐anisotropic media are influenced by the type and degree of material anisotropy, angle of inclination, and loading types. An illustrative example is given at the end of this article to investigate the effect of the type and degree of soil anisotropy (E/E′, G′/E′, and ν/ν′), pile inclination (α), and different loading types (a point load, a uniform skin friction, and a linear variation of skin friction) on vertical surface displacements. Results show that the displacements accounted for pile batter are quite different from those estimated from plumb piles, both driven in cross‐anisotropic media. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   
972.
In the present study, the stable isotopes δ18O and δ2H were used for assessment of the water balance in a heterogeneously structured catchment area in the Lusatian Lignite Mining District, in particular, for estimation of the annual groundwater inflow and outflow (IGW and OGW) of Mining Lake Plessa 117. The application of stable isotopes was possible since the water exchange in the catchment area had reached steady‐state conditions after the abandonment of mining activities in 1968 and the filling of the voids and aquifers by re‐rising groundwater in the years thereafter. Diverging slopes of the Evaporation Line and the Global Meteoric Water Line manifested as evaporation from the lake catchment area. The calculated isotope water balance was compared with the commonly used surface water balance, which is unable to differentiate between IGW and OGW, and with a local groundwater model. The groundwater model calculated an IGW of about 811 000 m3 yr?1 and an OGW close to zero, whereas the isotope water balance showed fluxes of about 914 000 and 140 000 m3 yr?1, respectively. Considering the contribution of the groundwater inflow to the total annual input into the lake (ΔIT) and the mean residence time (τ), where the groundwater model and the isotope water balance calculated 42 and 47% for ΔIT and 4·3 and 3·9 years for τ, respectively, it was shown that both water balance calculation methods led to comparable results despite the differences in IGW and OGW. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   
973.
A lumped water balance model was used to derive a monthly water storage series in the Salado–Juramento southern basin, for the period 1954–1986. The evapotranspiration term was estimated using the Bouchet's complementary relationship. Different evapotranspiration formulas following the concepts of potential evapotranspiration and wet environmental evapotranspiration were used. The regional average groundwater levels and the specific yield were used to tune Bouchet's equation. The extrapolation of the water storage series to a secular period (1901–2002) was achieved using a synthetic annual discharge series. The water storage was deficient for most of the century, i.e. more than 60 years; nevertheless in the last 30 years, the system recovers half of the water previously lost. The singular spectral analysis showed that a significant low‐frequency signal is present in the water storage and precipitation series. The main cause of water storage variability would be given by precipitation, in spite of the vast anthropogenic changes on the basin. Anthropogenic effects would be reflected in the river discharges, where no significant signal is detected before 1970; however, an annual signal is insinuated after that year. The conclusions of this work could be different if we only looked at the 1954–1986 period. The results of that period suggest that the basin is primarily accumulating water instead of being mainly in deficit. Thus, here we demonstrated the importance of the secular analysis to illustrate the complete basin behaviour. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
974.
Past and present glacier changes have been studied at Cordón Martial, Cordillera Fueguina Oriental, Tierra del Fuego, providing novel data for the Holocene deglaciation history of southern South America and extrapolating as well its future behavior based on predicted climatic changes. Regional geomorphologic and stratigraphic correlations indicate that the last glacier advance deposited the ice-proximal (“internal”) moraines of Cordón Martial, around 330 14C yr BP, during the Late Little Ice Age (LLIA). Since then glaciers have receded slowly, until 60 years ago, when major glacier retreat started. There is a good correspondence for the past 100 years between the surface area variation of four small cirque glaciers at Cordón Martial and the annual temperature and precipitation data of Ushuaia. Between 1984 and 1998, Martial Este Glacier lost 0.64 ± 0.02 × 106 m3 of ice mass (0.59 ± 0.02 × 106 m3 w.e.), corresponding to an average ice thinning of 7.0 ± 0.2 m (6.4 ± 0.2 m w.e), according to repeated topographic mapping. More detailed climatic data have been obtained since 1998 at the Martial Este Glacier, including air temperature, humidity and solar radiation. These records, together with the monthly mass balance measured since March 2000, document the annual response of the Martial Este Glacier to the climate variation. Mass balances during hydrological years were positive in 2000, negative in 2001 and near equilibrium in 2002. Finally, using these data and the regional temperature trend projections, modeled for different future scenarios by the Atmosphere-Ocean Model (GISS-NASA/GSFC), potential climatic-change effects on this mountain glacier were extrapolated. The analysis shows that only the Martial Este Glacier may survive this century.  相似文献   
975.
Interception loss has an important influence on the water yield of forested areas. Nevertheless, in most studies stemflow is not measured, therefore the question of how to determine the feasibility of optimizing interception and stemflow parameters simultaneously by matching daily simulated throughfall to fortnightly measurements of cumulative throughfall is an important one. By applying a daily empirical interception model, a goodness fit of 2·2 mm/day is obtained between observed and simulated cumulative throughfall. However, by applying the simple but robust Linking Test, it was shown that the parameters are non‐unique and falsely linked, i.e. inter‐relationships between different vegetation parameter sets give similar throughfall but non‐unique net precipitation. The Linking Test investigates the causes of obtaining falsely linked parameters and shows that objective equifinality is not the source of the problem. Objective equifinality occurs when an inappropriate objective function is used. The Linking Test also shows that falsely linked parameters are not caused by measuring throughfall on a non‐daily basis (termed frequency sampling equifinality). By expanding the interception model to the second degree, it was found that the non‐uniqueness is due to the inherent nature of interception and stemflow functions that behave similarly and therefore can easily compensate each other (termed similarity equifinality). It is also shown that a simple daily empirical exponential interception model developed for conifers in the uplands of the United Kingdom is suitable to model interception in Pinus radiata plantations in the Mediterranean climate of southern Australia by using only daily gross precipitation data and two parameters. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   
976.
中国新生代古地形演化的初步模型   总被引:8,自引:0,他引:8       下载免费PDF全文
新生代,中国地形景观发生了巨大变化,从早期的西倾地形变为现今的东倾地形,这种地形倒转可能是诱发亚洲乃至全球新生代气候环境格局总体改变的主要根源。本文基于流线场理论和向东挤出的构造假说,采用物质平衡方法,对中国新生代古地形演化进行半定量初步研究,结果显示中国新生代古地形演化呈现西部大幅度快速隆升,东部渐进式降低,中部变化较小的变化过程,总体地势的转变过程在50-40Ma期间内已基本完成,此后地势差距逐渐加剧,中国现今的地形格局是在近10Ma期间内最后形成。  相似文献   
977.
利用旁压试验参数确定地基土承载力和模量   总被引:4,自引:0,他引:4  
本文通过对工程勘察工作中所做的一些旁压试验与载荷试验资料进行对比分析,总结出利用旁压试验参数来确定地基土承载力和模量的方法。  相似文献   
978.
河北省地质环境评析   总被引:1,自引:0,他引:1  
地层,岩石,构造,水形成了地球表部的地质环境,地质灾害是地质环境演化为另一新的有序的自稳性状态的调整,文中论述了存在环境的破坏因素及对策,并对工程系统,地质环境及其与人类的关系问题进行思考。  相似文献   
979.
Modelling mean annual sediment yield using a distributed approach   总被引:3,自引:0,他引:3  
In this paper a spatially distributed model for the calculation of sediment delivery to river channels is presented (SEDEM: SEdiment DElivery Model). The model consists of two components: (1) the calculation of a spatial pattern of mean annual soil erosion rates in the catchment using a RUSLE (Revised Soil Erosion Equation) approach; and (2) the routing of the eroded sediment to the river channel network taking into account the transport capacity of each spatial unit. If the amount of routed sediment exceeds the local transport capacity, sediment deposition occurs. An existing dataset on sediment yield for 24 catchments in central Belgium was used to calibrate the transport capacity parameters of the model. A validation of the model results shows that the sediment yield for small and medium sized catchments (10–5000 ha) can be predicted with an average accuracy of 41 per cent. The predicted sediment yield values with SEDEM are significantly more accurate than the predictions using a lumped regression model. Moreover a spatially distributed approach allows simulation of the effect of different land use scenarios and soil conservation techniques. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   
980.
贡嘎山海螺沟冰川物质平衡、水交换特征及其对径流的影响   总被引:12,自引:17,他引:12  
在贡嗄山海螺沟冰川研究的基础上,提出计算该冰川物质平衡的两种方法,获得了较一致的结果,表明近10a来物质平衡平均为-470mm,与高亚洲边缘山脉的冰种同样处于强烈的衰退状态,该冰川有很高的物质平衡水平(2544mm)及水交换水平(3819mm),液相比例高(1/3),较小的稳定性系数(0.20),具有典型的季风海洋型冰川的水交换特征,由于冰川退缩冰川径流增加,预计2020年将达到临界状态,在气候持续暖变湿情况下,预测临界状态将延至2050年左右,冰川面积及储量将大幅度减少小。  相似文献   
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