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101.
Atef Masoud Kasem Sherwood WiseJr Mahmoud Faris Sherif Farouk Esam Zahran 《Arabian Journal of Geosciences》2017,10(20):455
Integration of calcareous nannofossil data, δ13C and δ18O values, and carbonate contents of the lower Paleocene–upper Paleocene sequence that crops out at the Misheiti section, East Central Sinai, Egypt, were used to denote the Danian/Selandian (D/S) and Selandian/Thanetian (S/T) stage boundaries. The study interval belongs to the Dakhla and Tarawan formations. Four calcareous nannofossil zones (NP4, NP5, NP6, and NP7/8) were recognized. The base of the Selandian Stage is tentatively placed at the lowest occurrences (LOs) of taxa ascribable to the second radiation of fasciculiths (i.e., Lithoptychius janii). This level is marked by a sudden drop of δ13C and δ18O values and carbonate content. No distinctive lithological changes were observed across the D/S boundary at the study section. A hiatus at the NP5/NP6 zonal boundary is indicated by the condensation of zones NP5 and NP6.The base of the Thanetian is placed at the base of Zone NP7/8 at the lithological change observed in correspondence to the boundary between the Dakhla and Tarawan formations. The δ13C and δ18O values abruptly decrease slightly above the base of Zone NP7/8. No consistent variations in the carbonate contents were recorded within Zone NP6 or across the NP6/NP7/8 zonal boundary. 相似文献
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105.
Natural and anthropogenic influences in the northeastern coast of the Nile delta,Egypt 总被引:4,自引:0,他引:4
Landsat enhanced thematic mapper imagery (ETM) of 2002 and aerial photography of 1955, combined with published charts and
field observations were used to interpret coastal changes in the zone between Kitchener drain and Damietta spit in the northeastern
Nile delta, previously recognized as a vulnerable zone to the effects of any sea level rise resulting from global warming.
The interpretation resulted in recognition of several changes in nine identified geomorphological land types: beach and coastal
flat, coastal dunes, agricultural deltaic land, sabkhas, fish farms, Manzala lagoon, saltpans, marshes and urban centers.
Reclamation of vast areas of the coastal dunes and of Manzala lagoon added about 420 km2 to the agricultural deltaic land.
About 48 km2 of backshore flats, marshes, salt pans and Manzala lagoon have been converted to productive fish farms. The main
urban centers have expanded; nearly 12.1 km2 have been added to their areas, and new urban centers (Damietta harbor and the New Damietta city) with total area reach of
~35.3 km2 have been constructed at the expense of vast areas of Manzala lagoon, coastal dunes, and backshore flats. As a consequence
of human activities, the size of Manzala lagoon has been reduced to more than 65%. Shoreline changes have been determined
from beach profile survey (1990–2000), and comparison of 1955 aerial photographs and ETM satellite image of 2002 reveal alongshore
patterns of erosion versus accretion. The short-term rate of shoreline retreat (1990–2000) has increased in the downdrift
side of Damietta harbor (≃14 m/year), whereas areas of accretion exist within the embayment of Gamasa and in the shadow of
Ras El Bar detached breakwaters system, with a maximum shoreline advance of ~15 m/year. A sandy spit, 12 km long, has developed
southeast of Damietta promontory. These erosion/accretion patterns denote the natural processes of wave-induced longshore
currents and sediment transport, in addition, the impact of man-made coastal protection structures. 相似文献
106.
Attitude determination by integration of MEMS inertial sensors and GPS for autonomous agriculture applications 总被引:3,自引:3,他引:3
Integration of Global Positioning System (GPS) and Inertial Navigation System (INS) technologies, which has widespread usage
in industry, is also regarded as an ideal solution for automated agriculture because it fulfils the accuracy, reliability
and availability requirements of industrial and agricultural applications. Agriculture applications use position, velocity
and heading information for automated vehicle guidance and control to enhance the yield and quality of the crop, and in order
to vary the application of fertilizer and herbicides according to soil heterogeneity at sub-field level. A loosely coupled
GPS/INS integration algorithm known as “AhrsKf” is introduced for automated agriculture vehicle guidance and control utilizing
MEMS inertial sensors and GPS. The AhrsKf can produce high-frequency attitude solutions for the vehicle’s guidance and control
system, by using inputs from a single survey grade L1/L2 antenna, eliminating the need for the previous two antenna solutions.
Given its agricultural application, the AhrsKf has been implemented with some specific design features to improve the accuracy
of the attitude solution including, temperature compensation of the inertial sensors, and the aid of plough lines of farm
lands. To evaluate the AhrsKf solution, two benchmarking tests have been conducted by using a three-antenna GPS system and
NovAtel’s SPAN-CPT. The results have demonstrated that the AhrsKf solution is stable and can correctly track the movement
of the farming vehicle. 相似文献
107.
The design code for each country is revised and updated based on an expected zone’s seismic intensities,geotechnical site classifications,structural systems,construction materials and methods of construction in order to provide more realistic considerations of seismic demand,seismic response,and seismic capacity.Based on the aforementioned provisions,structures designed according to different seismic codes may yield different performances for the same level of hazard.This study aims to investigate and compare the induced responses related to the earthquake-resistant design of reinforced concrete(RC)buildings according to the Saudi building code(SBC-301),American code(ASCE-7),uniform building code(UBC-97),and European code(EC-8).In order to account for the provision regarding the hazard specification and its effect on the induced seismic responses,four regions in the Kingdom of Saudi Arabia with different seismic levels are selected.The code provisions related to the specification of site classification and its effect on the induced design base shear are investigated as well.Significant differences are observed in the induced responses with the variation in seismic design codes for the considered seismic hazards and site classifications. 相似文献
108.
We present the physical parameters of three short period close binaries using data observed from the Kepler Space Telescope. All of these observations were taken in a single bandpass(which approximates the Johnson V-band). Our three systems are KIC 2715417, KIC 6050116 and KIC 6287172. The first system, KIC 2715417, is considered a semi-detached system with the secondary component filling its Roche lobe. The second system, KIC 6050116, is an overcontact system, while the third system, KIC 6287172, belongs to ellipsoidal variables as deduced from the Roche lobe geometry. For photometric analysis, we used the PHOEBE software package, which is based on the Wilson-Devinney code. Due to lack of spectroscopic data, the photometric mass ratios are determined from the analyses of light curves using the q-search method. The absolute parameters are determined using three different methods(Harmanec, Maceroni Van'tVeer and Gazeas Niarchos). 相似文献
109.
Acta Geochimica - Petrological and geochemical studies of Neoproterozoic metagabbros were carried out in the Muiswirab area, South Eastern Desert of Egypt. The Muiswirab area comprises of... 相似文献
110.
Sh. Hosseini Hashemi Mahmoud Karimi H. Rokni Damavandi Taher 《Ocean Engineering》2010,37(2-3):174-185
In this study Free vibration analysis of vertical rectangular Mindlin plates resting on Pasternak elastic foundation and fully or partially in contact with fluid on their one side is investigated for different combinations of boundary conditions. The plate is assumed to be one of vertical rectangular walls of a container in contact with fluid. In order to analyze the interaction of the Mindlin plate with the elastic foundation and fluid system, three displacement components of the plate are expressed in the Ritz method by adopting a set of static Timoshenko beam functions satisfying geometric boundary conditions in a Cartesian co-ordinate system. The method of separation of variables and the method of Fourier series expansion is used to model fluid and to obtain the exact expression of the motion of fluid in the form of integral equations. The fluid domain is finite in depth and width but infinite in the length direction. To demonstrate the accuracy of the present solution, convergence study is first carried out and then a few comparison studies are carried out with the available data in the literature. Finally, natural frequencies of rectangular plates are presented in tabular and graphical forms for different fluid levels, foundation parameters, aspect ratios, thickness to width ratios and boundary conditions. 相似文献