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81.
Astronomy Reports - This paper is devoted to examining the effects of charge and Weyl coupling parameter on the stable configuration of thin-shell wormholes. We use a cut and paste approach to... 相似文献
82.
In this paper, steel spheres embedded in a cement matrix were studied using numerical and physical ISRM testing procedures. A challenge in discrete element simulations is to select appropriate micro‐mechanical models and parameters, to recover the observed macro‐mechanical behavior. An ideal experiment on cohesive granular assemblies constructed identical to numerical ones would validate these micro models for a set of measured micro‐parameters. The first part of the paper summarizes the previous studies in this area, outlines such experimental methodology and depicts the steps followed for the preparation and the testing of cemented granular assemblies together with the derivation of micro‐parameters. The second part discusses the results of numerical and physical ISRM standard tests including uniaxial and triaxial compression, Brazilian tensile and shear box tests. Physical samples were prepared using steel balls bonded with Portland cement, cured under controlled laboratory conditions and tested in compression, tension and shearing. Acoustic emissions were monitored in uniaxial tests to characterize the damage thresholds relative to volumetric strains. Numerical simulations were conducted with PFC 3D using micro‐mechanical parameters derived from physical testing. Parametric sensitivity studies were carried out to look into the dependency of macroscopic responses on the parameters. The results from both numerical and physical tests showed good correspondence in macroscopic behavior i.e. peak strength, stages of damage, mode of failures. However, the numerical simulations reflected a stiffer mechanical response than physical assemblies. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
83.
Natural Hazards - New mapping through geomorphic analysis of tectonic landforms using a variety of freely available satellite data, including shuttle radar topography and Google Maps, has revealed... 相似文献
84.
Xueliang Wang Luqing Zhang Jixin Ding Qingfeng Meng Javed Iqbal Lihui Li Zhifa Yang 《Environmental Earth Sciences》2014,72(11):4639-4652
This study shows a rockfall susceptibility assessment at local scale in north Beijing of China, including the identification of rockfall sources onsite by terrain and rock discontinuities analysis and run-out distance prediction by Rocfall? simulation. Two types of rockfall were defined including one type on the cliffs with long inclined slopes and another type on the road slopes with low height. Two historical rockfall events were used to back-calibrating the parameters used for run-out distance simulation. Based on the work, rockfall susceptibility map at local scale was created in GIS, which was compared with the map obtained at regional scale (entire Huairou district scale). Due to the difference of approaches applied, procedure of assessment and types of source data acquired, the two resulting rockfall susceptibility maps are proved to be different. Still, both of them are useful and could be used at different level’s decision for rockfall prevention and mitigation. Different types of uncertainties exist in the study of rockfall susceptibility assessment. To reduce the uncertainties, studies on both approaches and techniques are suggested. 相似文献
85.
Alqadhi Saeed Mallick Javed Talukdar Swapan Ahmed Mohd. Khan Roohul Abad Sarkar Showmitra Kumar Rahman Atiqur 《Natural Hazards》2022,111(1):641-660
Natural Hazards - Co-occurrence events of droughts and heatwaves characterized by abnormal low soil moisture (SM) and high temperatures may cause more significant impacts on society and natural... 相似文献
86.
Khan Nafis Sadik Roy Sujit Kumar Mazumder Md. Touhidur Rahman Talukdar Swapan Mallick Javed 《Natural Hazards》2022,114(1):883-906
Natural Hazards - The confluence of the Ganges, Jamuna, and Padma rivers is one of the most dynamic in the world, an internationally important research area because of the confluence of two of the... 相似文献
87.
Mapping vulnerability to multiple stressors: climate change and globalization in India 总被引:7,自引:0,他引:7
Karen OBrien Robin Leichenko Ulka Kelkar Henry Venema Guro Aandahl Heather Tompkins Akram Javed Suruchi Bhadwal Stephan Barg Lynn Nygaard Jennifer West 《Global Environmental Change》2004,14(4):627
There is growing recognition in the human dimensions research community that climate change impact studies must take into account the effects of other ongoing global changes. Yet there has been no systematic methodology to study climate change vulnerability in the context of multiple stressors. Using the example of Indian agriculture, this paper presents a methodology for investigating regional vulnerability to climate change in combination with other global stressors. This method, which relies on both vulnerability mapping and local-level case studies, may be used to assess differential vulnerability for any particular sector within a nation or region, and it can serve as a basis for targeting policy interventions. 相似文献
88.
89.
A semi-analytical time integration method is proposed for the numerical simulation of transient groundwater flow in unconfined aquifers by the nonlinear Boussinesq equation. The method is based on the analytical solution of the system of ordinary differential equations with constant coefficients. While it is unconditionally stable and more accurate than the finite difference methods, the computational cost is much more expensive than (can be more than 10 times) that of the finite difference methods for a single time step. However, by partitioning the nonlinear parameters into linear and nonlinear parts, the costly computation can be performed only once. With larger and less variable time step sizes, the total computational cost can be significantly reduced. Three examples are included to illustrate the advantages and limitations of the proposed method. 相似文献
90.
Watershed prioritization using morphometric and land use/land cover parameters: A remote sensing and GIS based approach 总被引:4,自引:0,他引:4
Akram Javed Mohd Yousuf Khanday Subah Rais 《Journal of the Geological Society of India》2011,78(1):63-75
Jaggar watershed is a constituent of the Gambhir river basin, in eastern Rajasthan and covers an area of 352.82 km2, representing arid climate. The drainage network is dendritic to sub-dendritic pattern however parallel to sub-parallel has
also developed locally. The Jaggar watershed has been divided into fourteen sub-watersheds, designated as SW1 to SW14, for
prioritization purpose. The prioritization of the sub-watersheds has been done on the basis of morphometric analysis and land
use/land cover categories. Various morphometric parameters (linear and shape) have been determined for each sub-watershed
and assigned rank on the basis of value/relationship with erodibility so as to arrive at a compound value for final ranking
of the sub-watersheds. Land use/land cover mapping has been carried out using IRS LISS III data of 1998. Based on morphometric
and land use/land cover analysis and their ranks, the subwatersheds have been classified into four categories as very high,
high, medium and low in terms of priority for conservation and management of natural resources. The prioritization results
based on morphometry reveal that only SW7 and SW10 fall under very high priority, whereas SW6, SW11 and SW13 fall under very
high priority on the basis of land use/land cover analysis. However on the integration of morphometry and land use/land cover
only SW14 show common priority whereas rest have little or no correlation. 相似文献