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1.
From the laboratory experiments and field studies it has been shown that when a wave breaks directly on a vertical wall, impact pressures of high magnitude and short duration, are produced. Despite the recent advances made in collecting data on impact pressure histories and their spatial distributions, analyses on the structural behaviour of the walls loaded by the impact forces do not seem adequate. In the present study the theoretical analysis of the response characteristics of a caisson plate, having different aspect ratios, under the wave impact loading is investigated. Numerical results for the dynamic values of moments and transverse displacements are obtained by the method of finite elements. Some prerequisite experimental data for wave breaking and resulting impact pressures are provided. The static results for moments and deflections are also computed for comparing them with the dynamic values. The dynamic results are found significantly greater than the static values. The ratio between the dynamic and static values is called “Dynamic magnification factor” that varies with plate aspect ratio. Based on this factor a procedure is proposed which may have practical consequences in the design of caisson plates. 相似文献
2.
M Salih Kirkgz 《Ocean Engineering》1991,18(1-2)
Laboratory tests are conducted to measure the impact pressures of breaking waves on vertical, 5° forward, and 5, 10, 20, 30, and 45° backward sloping walls. The base structure of the wall has a foreshore slope of
. Regular waves are used throughout the experiments for all wall angles. The maximum impact pressures on the wall are shown to satisfy the log-normal probability distribution. It is found from the present experiments that the impact pressures and resulting forces on sloping walls can be greater than those on a vertical wall. On the seven different walls tested, the maximum impact pressures occur most frequently slightly below the still-water level. The pattern of the impact pressure history does not change with the slope of the wall, and as the probability of maximum impact pressure decreases, the pressures around the peak pressure region of the impact pressure histories remain longer. 相似文献
3.
Zinc–lead–barite deposits located in Lefan and Lower Banik localities of about 25 km northeast of Zakho City, Northern Iraq
consist of a group of strata-bound sulfides hosted in Upper Cretaceous (Upper Campanian–Maastrichtian) dolomitic limestone.
Carbonate-hosted ores contain 3.77% Zn, 2% Pb, and 5% Fe, while in lower Banik, they contain 1.5% Zn, 0.37% Pb, and 1.4% Fe.
Diagenetic processes, such as dolomitization and recrystalization in addition to the type of microfacies, provided appropriate
physical and chemical conditions that permitted the passage of ore-bearing fluids and participated in precipitation and ore
localization. These deposits are precipitated in a platform and developed within the Foreland Thrust Belt. Ore precipitated
as infill of intergranular dolomite porosity with replaced dolomite and rudist shells forming disseminated crystals that occupy
intergranular pore spaces around dolomite and calcite and as infill of dissolution spaces and fractures. 相似文献
4.
Salih Muhammad Awadh 《Arabian Journal of Geosciences》2009,2(2):139-142
Reflectance (R%) and internal reflections (IR) in the iron variant, sphalerite, are investigated by using the scanning electron microprobe and reflected light microscope. Iron contents in sphalerite positively affect reflectance and can be considered as a control factor of internal reflections color. Internal reflections of sphalerite grains that contain less than 10% Fe appear to be whitish yellow color but are with reddish brown color when Fe rises to 10% to 17%. This work is an effort for developing ore microscopy and ore petrography technique by using the optical properties as a geochemical tool for fast preliminary estimating iron content in sphalerite by using reflected light microscope. 相似文献
5.
Analysis of dry and wet climate characteristics at Uttarakhand (India) using effective drought index
Malik Anurag Kumar Anil Kisi Ozgur Khan Najeebullah Salih Sinan Q. Yaseen Zaher Mundher 《Natural Hazards》2021,105(2):1643-1662
Natural Hazards - Drought is a complex natural disaster that adversely affects human life and the ecosystem. A variety of drought indexes are available for monitoring meteorological drought events.... 相似文献
6.
Assoc. Prof. Dr. M. A. Mohamed Salih 《GeoJournal》1991,25(1):51-57
During the past half century Moro society has undergone immense economic and social transformations. The Moro adopted rural-urban and rural-rural migration, among other things, to diversify their incomes and augment their sources of livelihood. Politically, the introduction of modern political parties since independence in 1956 and the emergence of regional movements have influenced Moro perception of their reality and relationship with their Hawazma and Jellaba neighbours.I argue in this paper that due to disappointments emanating from harsh living conditions in discordant Northern Sudanese towns, the Moro translate past experiences into a common identity. Migration, in this sense, is seen as a major factor in explaining the Moro crisis of identity and their oscillation between integration and aloofness or modernity and traditionalism. 相似文献
7.
The main results that derived from this study is the quantitative determination of subsurface water balance and the water loses along flow line during drought decade (before 2000–2009), with intense exploitation of groundwater from water wells. The hydrogeological data are presented as spatial distribution maps and three dimensional models. The results are correlated with the main hydrogeologic control points including (storage and transmissivity coefficients, groundwater depths, aquifers thickness, lateral extensions, well productivity) to determine the preferable hydrogeologic districts for development and exploitations, avoiding groundwater depletion as captured zone flow. Based on the isotope analysis of deuterium, oxygen-18, tritium, carbon-13, and carbon-14, the recharge of the aquifer is originated to direct infiltration of atmospheric water through exposure outcrops within Hauran catchments area. The isotope compositions also show that the groundwater is a mixture of an old groundwater with modern recharge in the areas adjacent to Rutba. The fact that the Mullusi aquifer is of major importance as the water supply of people in Rutba region, particularly, for increasing demand of water resources and sustainability assessment in the future, this study developed a reliable strategic suggested plan in groundwater supply, based on groundwater exploitation and amount of safe yield within Dhabaa basin. 相似文献
8.
The Burdigalian mixed siliciclastic–carbonate deposits of the Dam Formation are well-exposed in Al Lidam area, in the eastern province of Saudi Arabia. They represent a shallow part of the Arabian plate continental margin. The Dam Formation is correlatable to the Miocene reservoirs in both Iran and Iraq. Therefore, studying the Dam Formation lithologic heterogeneity in a small distance with high resolution could help in further work related to pattern prediction of the Miocene reservoir properties. High-resolution sedimentological investigation was carried out through six outcrops. The facies parameters (lithology, sedimentary structures, main fossils, paleocurrent patterns and geometries of the sedimentary bodies) were described. The results revealed 15 lithofacies that have been further grouped into 7 lithofacies associations 5 of which are carbonates and include (1) interbedded dolostone and evaporates, (2) microbialite buildup, (3) ooid-dominated grainstones, (4) burrowed skeletal peloidal wackestone–packstone and (5) mollusc-dominated wackestone–packstone. The remaining two associations are of siliciclastics and include (6) intertidal siliciclastics and (7) wave-dominated siliciclastics. These lithofacies were interpreted to reflect deposition in a mixed siliciclastic–carbonate ramp system that includes subtidal, shoreface, intertidal, foreshore, supratidal and estuarine deposits in a shallowing-upward succession. Each one of these lithofacies association has distinct geometry and architecture pattern. Oolites and heterozoan lithofacies occur as sheets and show great continuity along the strike direction. Oolites pass laterally in the dip direction into more skeletal- and peloid-dominated zones, whereas heterozoan lithofacies stay continuous in the dip directions and change from siliciclastic to carbonate heterozones. In contrast, microbialite lithofacies lack continuous beds and occur as localised bioherms and biostroms. Channelised lithofacies are restricted laterally into isolated channel bodies and vertically in the contact boundary between siliciclastic and carbonate lithofacies, whereas the interbedded dolostone and evaporite lithofacies form distinct, relatively thick continuous layers. With continuous exposures in both strike (1.2 km) and dip (0.15 km) directions, the outcrops in the Al Lidam area provide unique opportunity to study the heterogeneity among lithofacies of the mixed siliciclastic–carbonate system of the Dam Formation. Such study may provide insights to predict occurrence and distribution of lithofacies bodies in their equivalent reservoirs which are important for reservoir characterisation. 相似文献
9.
Anamolous ionospheric TEC variations prior to the Indonesian earthquake (M 7.1) of November 15, 2014
Salih Alcay 《Geomagnetism and Aeronomy》2017,57(3):301-307
This paper investigates preearthquake ionospheric variations with the use of TEC of Global Ionospheric Maps (GIMs) and regional maps based on Precise Point Positioning (PPP) during the 7.1-M Indonesian earthquake that occurred on November 15, 2014. TEC maps corresponding to 10 days before to 4 days after the event were examined. In addition, a time series of TEC values according to the PPP maps were also evaluated. In addition to GIMs, it was possible to detect TEC variations with PPP maps. The results showed that ionospheric TEC decreased strikingly 4 days prior to the earthquake. This TEC variation was highly likely related to seismic activity. 相似文献
10.
From the experimental studies in recent years, it has become known that when a wave breaks directly on a vertical faced coastal structure, high magnitude impact pressures are produced. The theoretical and experimental studies show that the dynamic response of such structures under wave impact loading is closely dependent on the magnitude and duration of the load history. The dynamic analysis and design of a coastal structure can be succeeded provided the design load history for the wave impact is available. Since these types of data are very scarce, it is much more convenient to follow a method which is based on static analysis for the dynamic design procedure. Therefore, to facilitate the dynamic design of a vertical plate that is exposed to breaking wave impact, a multiplication factor called “dynamic magnification factor” is herein presented which is defined as the ratio of the maximum value of the dynamic response to that found by static analysis. The computational results of the present study show that the dynamic magnification factor is a useful ratio to transfer the results of static analysis to the dynamic design of a coastal plate for the maximum impact pressure conditions of pmax/γH0≤18. 相似文献