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排序方式: 共有75条查询结果,搜索用时 15 毫秒
1.
Fathy Shaaban Turki M. Habeebullah Essam A. Morsy Safwat Gabr 《Arabian Journal of Geosciences》2016,9(20):754
This work presents the application of the ground-penetrating radar (GPR) method and electric resistivity tomography (ERT) technique in outlining a zone of contamination due to the light non-aqueous phase liquid (LNAPL) plume underground in the area of an impacted fuel station, close to Abha City. The GPR has been performed using SIR3000 unit with the 100 and 400 MHz antennas. The main objective of the GPR survey was to evaluate the lateral extension of contamination. The complex GPR signature of the plume was well characterized. Low reflectivity zone corresponds to hydrocarbon vapor phase in the vadose zone. Enhanced reflections are associated with free and residual products in the fractured saturated zone directly above the water table. An electric resistivity tomography (ERT) survey was performed on four profiles within the site to investigate the vertical and horizontal extent of the contamination plume and to define the bottom of the landfill. The 2D electric profiles show the presence of low-resistivity (4O to 37 Ω m) anomalies that refers to the presence of accumulated hydrocarbons. From the interpretation of the GPR and ERT profile, it was possible to locate the top and bottom of the contamination plume of the waste disposal site. The radar signal penetrated deep enough and enabled the identification of a second reflector at approximately 10-m deep, interpreted as the hard basement surface which causes the strong amplitude reflection in the GPR profile. The results of GPR and ERT showed good agreement. 相似文献
2.
Sattam Almadani Elkhedr Ibrahim Mahfooz Hafez Hussain Alfaifi Talal Alharbi Kamal Abdelrahman Essam Abdel-Motaal 《Arabian Journal of Geosciences》2018,11(2):33
In the present study, the existence of cavities, voids, and fractures was verified at the site of the El-Elb Dam, which is located to the northwest of Riyadh City across Wadi Hanifa, using 2D electrical resistivity tomography (ERT) and ground-penetrating radar (GPR) techniques. For this purpose, four ERT profiles were measured on the downstream side of the El-Elb Dam using the Syscal Pro Switch-72 resistivity meter. In addition, a GPR survey using a 400-MHz antenna and a SIR-3000 instrument was conducted along five profiles above the stilling basins on the downstream side of the dam and one radar profile was measured outside the stilling basins area across the course of the wadi. The resultant geophysical data were interpreted with the aid of information from a field-based structural and stratigraphic evaluation of the outcropped bedrock on the banks of the wadi course. The analysis of the inverted ERT and filtered radar sections revealed several resistivity and electromagnetic reflection anomalies that are identified laterally and vertically across the measured sections. These anomalies indicate the presence of fractures and karst features affected the limestone bedrock in the dam site. These near-surface karstified and fractured strata represent a critical hazard to the structural safety of the dam. 相似文献
3.
Hesham M. El-Kaliouby Safwat A. Hussain Abd El-Rahim Bayoumi Essam A.El-diwany Essam A. Hashish 《Geophysical Prospecting》1995,43(5):595-603
The aim of this work is to consider the phenomenon of negative response and its detectability in a polarizable half-space formed of Clay-water mixture which commonly exists in water aquifers and which can be used as a simple indicator of the presence of Underground water. We make use of an analytical treatment for the transient voltage induced in a coincident loop lying on a half-space as a basis for our computations. A Cole-Cole model is used to represent the Clay with appropriate parameters. As saturated Clay is characterized by high conductivity and moderate chargeability, it is hardly detectable relative to the practical noise level. However, there are optimum Clay parameters that offer a maximum negative response. It is also observed that for a very short time constant τ in the Cole-Cole model, the amplitude of the negative response decreases with the decrease of the time constant due to the fast decay of the polarization current. Finally, it is found that there is an optimum value for the loop radius which gives the largest value of the negative response and this loop radius depends on the model parameters. 相似文献
4.
5.
Daniela Comelli Massimo D'orazio Luigi Folco Mahmud El‐Halwagy Tommaso Frizzi Roberto Alberti Valentina Capogrosso Abdelrazek Elnaggar Hala Hassan Austin Nevin Franco Porcelli Mohamed G. Rashed Gianluca Valentini 《Meteoritics & planetary science》2016,51(7):1301-1309
Scholars have long discussed the introduction and spread of iron metallurgy in different civilizations. The sporadic use of iron has been reported in the Eastern Mediterranean area from the late Neolithic period to the Bronze Age. Despite the rare existence of smelted iron, it is generally assumed that early iron objects were produced from meteoritic iron. Nevertheless, the methods of working the metal, its use, and diffusion are contentious issues compromised by lack of detailed analysis. Since its discovery in 1925, the meteoritic origin of the iron dagger blade from the sarcophagus of the ancient Egyptian King Tutankhamun (14th C. BCE) has been the subject of debate and previous analyses yielded controversial results. We show that the composition of the blade (Fe plus 10.8 wt% Ni and 0.58 wt% Co), accurately determined through portable x‐ray fluorescence spectrometry, strongly supports its meteoritic origin. In agreement with recent results of metallographic analysis of ancient iron artifacts from Gerzeh, our study confirms that ancient Egyptians attributed great value to meteoritic iron for the production of precious objects. Moreover, the high manufacturing quality of Tutankhamun's dagger blade, in comparison with other simple‐shaped meteoritic iron artifacts, suggests a significant mastery of ironworking in Tutankhamun's time. 相似文献
6.
In arid‐region wadis, groundwater storage lies within shallow Quaternary alluvium deposits, which are connected with the present‐day hydrological cycle and, therefore, are replenished due to occasional runoff and flash flood occurrences. The groundwater resources are precious in these environments; therefore, their potentiality must be assessed with care in the best manner. The aquifer potentiality is calculated after the storativity and transmissivity parameter estimations, which require rather long‐duration field tests with restrictive assumptions in the theoretical model developments, such as the homogeneity and isotropy. It is the main purpose of this paper to expose the fundamentals of the slope‐matching procedure (SMP) and its application for short‐duration field tests in arid‐region aquifers. In this manner, the subsurface hydrogeological behaviours of the bored land pieces at and around the well locations are prospected in a detailed and refined manner. It is shown that in many cases the classical techniques are appropriate, inconvenient and inapplicable with conclusive reliable results and conclusions. The application of the SMP is presented for some aquifer tests from the central western part of the Kingdom of Saudi Arabia. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
7.
PhotoelectricB andV observations of the W UMa-type system OO Aql have been obtained for 11 nights during the period from 22 June–30 July, 1987. A total of 978 observations were obtained in eachB andV filter. All these observations were transformed to theB andV colours of theUBV standard system. Five light curves for primary and secondary eclipses were obtained, its times of minima were determined and a new linear ephemeris was given. The period changes of the system were discussed. 相似文献
8.
9.
Omran Frihy Essam Deabes Wahid Moufaddal Adam El-Shahat 《Marine Georesources & Geotechnology》2013,31(5):408-418
Mineralogical and textural analyses of 45 undisturbed short cores and 80 grab sediment samples, collected from five frequently dredged navigational areas within harbors and water pathways of the Nile delta littoral system, were utilized for evaluation of these sediments as potential source of economic heavy minerals (EHMs). Results of mineralogical characterization indicate that the average total heavy mineral (HM) concentrations are as follows: Abu Qir Bay (1.7%), Rosetta estuary (3.1%), Burullus fishing port (4.5%), Damietta Harbor (2.9%), and El Gamil lagoon inlet (1.9%). Assessment of HM grades indicates predominance of magnetite, ilmenite, hematite, leucoxene, garnet, zircon, and rutile. Results of the feasibility analysis indicate that dredged sediments at these study areas are considered as a potential source of EHMs and economically promising to be mined for HMs. The present study suggests a practical operative plan of two successive phases for HMs recycling: (1) in-situ initial separation of HMs on the dredger deck using wet-gravity spirals, then (2) transportation of the recovered HM concentrates to an onshore processing plant to selectively separate individual HMs via wet and dry magnetic and electrostatic separators. Alternatively, dredged sediments can be directly pumped to a nearby onshore area as stockpile to be recycled afterward in inland processing plant. 相似文献
10.
The Aluto-Langano geothermal field is located in the central southern portion of Ethiopia within the Ethiopian Rift Valley.
The gravity of the area was surveyed in an attempt to delineate the subsurface structure and to better understand the relationship
between the geothermal systems and the subsurface structure. The gravity data were analyzed using integrated gradient interpretation
techniques, such as the Horizontal Gradient (HG), Source Edge Detection (SED), and Euler Deconvolution (ED) methods. These
techniques detected many faults that were compared with the mapped faults in the surface geology. The results of the present
study will lead to an improved understanding of the geothermal system in the study area and aid the future geothermal exploration
of the area. 相似文献