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841.
842.
基于动力可靠性分析的滑移隔震体系的优化设计 总被引:10,自引:2,他引:8
本文探讨了滑移隔震体系在零均值高斯白噪声地震作用下的优化设计问题,首先利用编译等效线性化方法并按首次超超损坏泊松过程模型的双壁问题得到质点的滑移可靠性函数,然后采用拉格朗日乘子法进行了该滑移隔震体系基于动力可靠性分析的优化设计。 相似文献
843.
Shallow landslide hazard assessment using a physically based model and digital elevation data 总被引:6,自引:1,他引:5
A model for the analysis of topographic influence on shallow landslide initiation is applied to an experimental mountain
basin where high-resolution digital elevation data are available: the Cordon catchment (5 km2) located in northern Italy. The model delineates those areas most prone to shallow landsliding due to surface topographic
effects on hydrologic response. The model is composed of two parts: a steady-state model for shallow sub-surface runoff and
an infinite-slope Coulomb failure model which assumes that the soil is cohesionless at failure. An inventory of landslide
scars is used to document sites of instability and to provide a test of model performance by comparing observed landslide
locations with model predictions. The model reproduces the observed distribution of landslide locations in a consistent way,
although spatial variations in soil strength and transmissivity, which are not accounted for in the model, influence specific
distribution of landslide areas within regions of similar topographic control.
Received: 15 October 1996 · Accepted: 25 June 1997 相似文献
844.
用于油藏描述的三维地质体剖分及体积计算方法 总被引:3,自引:0,他引:3
针对计算机模拟中的关键问题,即三维地质体的剖分和体积计算方法进行了较深入的讨论。在将地质体剖分为内部单元和边缘单元之后,又将内部单元细分为中间的长方柱体和两端的不规则多面体。通过分析,给出了计算内部单元和边缘单元不规则多面体的体积计算公式,并通过对两种理论模型的剖分和计算结果,说明了方法的正确性和提高精度的有效性 相似文献
845.
Acid Rain and Below-Cloud Scavenging in South-Western China 总被引:1,自引:0,他引:1
PETER A. TANNER HENG-CHI LEI MEI-YUAN HUANG ZHI-LAI SHEN 《Journal of Atmospheric Chemistry》1997,27(1):71-78
Major urban areas in south-western China exhibit unique air pollutionproblems due to increasing use of high sulphur-content fuels in an environmentof unfavourable topography and climate. Ambient levels of sulphur dioxideexceed the air quality objectives, and this gas is the major precursor of acidrain. Cloudwater chemistry studies are reported for urban, suburban andcountryside locations, during the period 1985–1989. Although cloudwateracidity was found to increase towards the cloud base, the acidity was muchgreater for rainwater samples collected simultaneously, and was morepronounced in urban rather than neighbouring suburban or countryside regions.The main contribution to the acidity arises from below-cloud scavenging of gasand aerosol and model calculations are able to simulate this behaviour. 相似文献
846.
在一维简化地球模型下,推导了台风脉动应力公式和应变公式,计算了台风脉动应力量级,统计了台风与地震在时间与空间上的关系,并对两个震例进行了分析.结果表明,台风产生的脉动对地震有触发作用. 相似文献
847.
Summary The objective of this study is to determine the parameters which influence coal's mechanical behaviour. The two coals examined (HBL, Simon, France and Barro Banco, Brazil) structurally originated from different deposits. The differences are readily explained by the contrasting composition of vitrain, clarain, durain and fusain. Their mechanical behaviour is linked to their petrographical composition. The Lorrainain coal behavioural pattern was evaluated. It is elastobrittle or elastoplastic with progressive failure. Brazilian coal behaves according to a pattern of elastoplastic with progressive failure or perfect elastoplastic. 相似文献
848.
Two samples from the upper and lower horizons of the Irati oil shale of the Paraná Basin, Brazil were sampled in a single borehole, and analysed using organic petrography and geochemistry. The results are interpreted in terms of the kerogen type, maturity and depositional environment of the two horizons.Organic petrography shows the oil-shales to be composed of a mineral groundmass, mainly clay minerals, carbonate and pyrite, associated, and sometimes impregnated, with fluorescing organic material and disseminated phytoclasts. Humic material is fairly rare and mostly present as very small particles. The liptinitic particles are mostly alginite (A and B), sporinite and more rarely resinite. Reflectance measurements (upper seam = 0.34% R0; lower seam = 0.40% R0) indicate an equivalent rank of lignite/sub-bituminous coal (ASTM), i.e. immature with respect to oil and gas generation. Different organic geochemical methods (Rock-Eval pyrolysis, solvent extraction, GC and GC-MS) demonstrate both samples to be immature, rich oil-shales (100–114 kg/ton) containing Type I kerogen, of a dominantly bacterially-degraded algal origin deposited in a lacustrine environment. The presence of Botryococcus suggests deposition under fresh/brackish water conditions.A tentative interpretation of the extract and vitrinite reflectance data suggests a maximum paleo-burial of between 1.3 and 2.8 km for the analysed section of the Irati Formation. 相似文献
849.
850.
针对干旱地区平原绿洲水土资源利用的特点,建立了以农区土壤水为中心的干旱区平原绿洲散耗型水文模型。散耗型模型考虑了水在不同介质和不同形态之间的交换或转化,并重点考虑人类活动如引水灌溉、地下水的开采等对水平衡的影响。模型把研究区划分为河段、泉井、水库湖泊、农区和非农区五类水均衡模块,水均衡模块之间通过地表渠系、地下水侧渗进行水量交换。应用模型可以对研究区农区、非农区各自的蒸发量、农区向非农区地下水迁移量等干旱区主要水分散耗项进行分析。 相似文献