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51.
利用岩石滑移破坏强度理论,研究地下开采时掌子面前方岩体中的应力和应变状态,分析引起支撑压力区岩体体积变化的主要因素,并通过对体积变形状态及变形结果的分析,得到深部围岩区域破裂现象的发生条件。结果显示,深部岩体工程中掌子面前支撑压力区域体积变化的主要原因是最大支撑压力区域在各向不均匀压缩的条件下产生的“分层剥离”,该机制可解释分区破裂化现象。同时,根据浅部与深部岩体工程的不同特征现象,给出以单轴抗压强度表示的界定浅部与深部工程的解析表达式,并认为对于较薄的岩层,普朗特解是一种很好的近似 相似文献
52.
Exploring the structure of the U.S. intercity passenger air transportation network: a weighted complex network approach 总被引:1,自引:0,他引:1
The U.S. airline network is one of the most advanced transportation infrastructures in the world. It is a complex geospatial
structure that sustains a variety of dynamics including commercial, public, and military operations and services. We study
the U.S. domestic intercity passenger air transportation network using a weighted complex network methodology, in which vertices
represent cities and edges represent intercity airline connections weighted by average daily passenger traffic, non-stop distance,
and average one-way fares. We find that U.S. intercity passenger air transportation network is a small-world network accompanied
by dissortative mixing patterns and rich-club phenomenon, implying that large degree cities (or hub cities) tend to form high
traffic volume interconnections among each other and large degree cities tend to link to a large number of small degree cities.
The interhub air connections tend to form interconnected triplets with high traffic volumes, long non-stop distances, and
low average one-way fares. The structure of the U.S. airline network reflects the dynamic integration of pre-existing urban
and national transportation infrastructure with the competitive business strategies of commercial airlines. In this paper
we apply an emerging methodology to representing, analyzing, and modeling the complex interactions associated with the physical
and human elements of the important U.S. national air transport and services infrastructure. 相似文献
53.
Free vibrations of three-dimensional extensible marine cables with specified top tension via a variational method 总被引:1,自引:0,他引:1
This paper presents a model formulation that can be used for analyzing the three-dimensional vibration behaviours of an inclined extensible marine cable. The virtual work-energy functional, which involves strain energy due to axial stretching of the cable and virtual work done by external hydrostatic forces is formulated. The coupled equations of motion in the Cartesian coordinates of global systems are obtained by taking into account the difference between Euler’s equations and equilibrium equations. The method of Galerkin finite element is used to obtain the mass and stiffness matrices which are transformed into the local coordinate systems. Then the eigenvalue problem is solved to determine its natural frequencies and corresponding mode shapes. The model formulation developed herein is conveniently applied for the cases of specified top tension. The numerical investigations are carried out to demonstrate the validity of the model and to explore in details the influence of various parameters on the behaviours of marine cables. Results for the frequency avoidance phenomenon, maximum dynamic tension and coupled transverse mode shapes are presented and discussed. 相似文献
54.
探究孤子自频移现象,从啁啾的角度来解释其产生的原因。运用数学求解及数值模拟方法,通过MATLAB编程画出了啁啾演变图,据此来研究自频移现象。研究结果表明,在高阶非线性效应中,脉冲内拉曼散射、色散和自相位调制共同所致的啁啾,与无拉曼散射效应时产生的啁啾相比,发生一系列新的变化:啁啾的中心发生漂移且图形的前后沿不对称,即负啁啾的峰值的绝对值大于正啁啾的峰值,这说明了脉冲频谱“红移”的谱峰变宽,或者说频谱移向了长波长方向—即人们所说的孤子自频移现象。 相似文献
55.
介绍近年来新发现的海上结构物在高海况下遇到的一种现象--ringing高频共振响应现象及这一现象现有的研究成果,包括该现象的发现过程、特征、产生的机理及研究方法等。提出了研究ringing现象的一种可能的新方法。 相似文献
56.
57.
A class of E1 Niйo atmospheric physics oscillation model is considered. The E1 Niйo atmospheric physics oscillation is an abnormal phenomenon involved in the tropical Pacific ocean-atmosphere interactions. The conceptual oscillator model should consider the variations of both the eastern and western Pacific anomaly patterns. An E1 Niйo atmospheric physics model is proposed using a method for the variational iteration theory. Using the variational iteration method, the approximate expansions of the solution of corresponding problem are constructed. That is, firstly, introducing a set of functional and accounting their variationals, the Lagrange multiplicators are counted, and then the variational iteration is defined, finally, the approximate solution is obtained. From approximate expansions of the solution, the zonal sea surface temperature anomaly in the equatorial eastern Pacific and the thermocline depth anomaly of the sea-air oscillation for E1 Niйo atmospheric physics model can be analyzed. E1 Niйo is a very complicated natural phenomenon. Hence basic models need to be reduced for the sea-air oscillator and are solved. The variational iteration is a simple and valid approximate method. 相似文献
58.
59.
电弧光谱分析高含量铁矿石产生蹦跳比较严重。最主要的是氧化铁在高温下与炽热的碳电极之间发生了氧化还原反应产生的二氧化碳气体,这些气体无法排除,随着燃弧继续增多,就会把熔球冲掉,从而产生蹦跳现象。针对容易产生蹦跳现象的试样在分析时应采取的预防措施和手段,最简易可行的方法就是用锯口电极,可防止蹦跳现象的产生。 相似文献
60.
本文简述了铜岩山矿床地质概况,分析了矿区内蚀变带和主要矿体特征,综合研究本矿区剥蚀程度地球化学判别指标。利用累乘晕比值方法,建立5组累乘元素比值公式,求得各组剥蚀系数,以显示矿区内矿体矿化序列和剥蚀程度。发现本矿区内高温成矿元素分布在矿体上方,中低温成矿元素聚集在矿体下部之矿化反序列现象。 相似文献