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排序方式: 共有65条查询结果,搜索用时 47 毫秒
1.
Fahad N. Al-Barakah Aly Anwar A. Abaakhel Emad H. S. Al-Rizkid Abdulwahid M. Alghamdi Abdulaziz G. Al-Sewailem Mohammad S. 《Water Resources》2020,47(5):877-891
Water Resources - The objective of this study was to compare and assess the quality and study the hydrochemistry of groundwater in the Al-Baha and Al-Qassim areas, representing the Arabian Shield... 相似文献
2.
In this study, the spatio-temporal evolution of Yellowstone deformation between 1992 and 2009 is monitored using interferometric
synthetic aperture radar (InSAR) data acquired by the European Remote-Sensing Satellites (ERS-1 and ERS-2) and the Environmental
Satellite (ENVISAT). These data are combined with continuous global positioning system (GPS) measurements to identify four
discrete episodes of caldera subsidence and uplift, these episodes are: 1992–1995 (subsidence of 2.7 cm/year), 1996–2000 (subsidence
of 0.5 cm/year, with local uplift of 1.7 cm/year at Norris), 2000–2004 (subsidence of 0.7 cm/year, with local uplift of 0.6 cm/year
at Norris), and 2004–2009 (uplift of 3–8 cm/year, with local subsidence of 1–4 cm/year at Norris). We construct the full three-dimensional
velocity field of Yellowstone deformation for 2005–2006 from ascending and descending ENVISAT orbits. The InSAR three-dimensional
velocity field and three-component GPS measurements indicate that the majority of the observed deformation (3–8 cm/year) across
the Yellowstone caldera and near Norris Geyser Basin (NGB) occurred in the vertical direction between the summers of 2005
and 2006. During this time, significant lateral displacements of 3–7 cm/year also occurred in the east–west direction at the
southeastern and western rims of the Yellowstone caldera and in the area between Hebgen Lake and NGB. Minor north–south displacements
of about 0.2 cm/year also occurred, however, in the southwestern section of the caldera and near Yellowstone Lake during the
same period. The calculated three-dimensional velocity field for 2005–2006 implies the existence of two pressure-point sources,
beneath the two structural resurgent domes in the Yellowstone caldera, connected by a planar conduit, rather than a single,
large sill as proposed in previous studies. Furthermore, no measurable displacements occurred along any fault zone across
the caldera during the entire period of observation (1992–2009). Therefore, we infer that magmatic and hydrothermal processes
beneath the Yellowstone caldera and NGB were the main sources of deformation. 相似文献
3.
M. A. El-Borie A. M. El-Taher N. E. Aly A. A. Bishara 《Astrophysics and Space Science》2018,363(5):106
Data of geomagnetic indices (aa, Kp, Ap, and Dst) recorded near 1 AU over the period 1967–2016, have been studied based on the asymmetry between the interplanetary magnetic field (IMF) directions above and below of the heliospheric current sheet (HCS). Our results led to the following conclusions: (i) Throughout the considered period, 31 random years (62%) showed apparent asymmetries between Toward (\(\mathbf{T}\)) and Away (\(\mathbf{A}\)) polarity days and 19 years (38%) exhibited nearly a symmetrical behavior. The days of \(\mathbf{A}\) polarity predominated over the \(\mathbf{T}\) polarity days by 4.3% during the positive magnetic polarity epoch (1991–1999). While the days of \(\mathbf{T}\) polarity exceeded the days of \(\mathbf{A}\) polarity by 5.8% during the negative magnetic polarity epoch (2001–2012). (ii) Considerable yearly North–South (N–S) asymmetries of geomagnetic indices observed throughout the considered period. (iii) The largest toward dominant peaks for \(aa\) and \(Ap\) indices occurred in 1995 near to minimum of solar activity. Moreover, the most substantial away dominant peaks for \(aa\) and \(Ap\) indices occurred in 2003 (during the descending phase of the solar cycle 23) and in 1991 (near the maximum of solar activity cycle) respectively. (iv) The N–S asymmetry of \(Kp\) index indicated a most significant away dominant peak occurred in 2003. (v) Four of the away dominant peaks of Dst index occurred at the maxima of solar activity in the years 1980, 1990, 2000, and 2013. The largest toward dominant peak occurred in 1991 (at the reversal of IMF polarity). (vi) The geomagnetic indices (aa, Ap, and \(Kp\)) all have northern dominance during positive magnetic polarity epoch (1971–1979), while the asymmetries shifts to the southern solar hemisphere during negative magnetic polarity epoch (2001–2012). 相似文献
4.
Abdullah Gamil M. S. El Aal Ahmed Abd Radwan Ahmed E. Qadri Talha Aly Nevin 《Acta Geotechnica》2023,18(1):105-125
Acta Geotechnica - One of the most important geotechnical parameters in studying the engineering behavior of a rock mass is slake durability. The major goal of this research is to test how a series... 相似文献
5.
Okuhata Brytne K. El-Kadi Aly I. Dulai Henrietta Lee Jonghyun Wada Christopher A. Bremer Leah L. Burnett Kimberly M. Delevaux Jade M. S. Shuler Christopher K. 《Hydrogeology Journal》2022,30(1):231-250
Hydrogeology Journal - Fresh groundwater is a critical resource supporting coastal ecosystems that rely on low-salinity, nutrient-rich groundwater discharge. This resource, however, is subject to... 相似文献
6.
Ahmed Aly Kamel 《Celestial Mechanics and Dynamical Astronomy》1971,4(3-4):397-405
To develop the perturbation solution of the non-Hamiltonian system of differential equationsy=g(y, t; ), it is sufficient to obtain the perturbation solution of a Hamiltonian system represented by the HamiltonianK=Y·g(y, t; ) which is linear in the adjoint vectorY. This Hamiltonization allows the direct use of the perturbation methods already established for Hamiltonian systems. To demonstrate this fact, a Hamiltonian algorithm developed by this author and based on the Lie-Deprit transform is applied to the Hamiltonized system and is shown to be equivalent to the application of the non-Hamiltonian form of this same algorithm to the original non-Hamiltonian system. 相似文献
7.
High and Aswan Dams Authority (HADA) proposed a plan aiming at constructing a rockfill dam in the Kalabsha area, about 60 km south of Aswan High Dam. The aim of this dam is to restrain the overflow of water to the Kalabsha Valley for keeping one billion cubic meters from being lost due to seepage and evaporation. The safety of dams during earthquakes is extremely important because failure of such a structure may have disastrous consequences on life and property. Therefore, different factors were considered as part of a site assessment. Five seismic source zones, close enough to the site to give rise to potentially damaging earthquake ground motions, were identified. Seven active faults that have the potential for producing significant earthquakes and that pass through or near the dam site were also identified. The earthquake loading represented by ground motions at the site was evaluated. Probabilistic seismic hazard procedures were used for assessing the earthquake loading at six individual sites using Area-and Line-Source Models (ASM & LSM). The ASM is based on current observed seismicity, whereas the LSM is based on geological slip rates. The output represents the expected acceleration amplitude with 90 percent probability of not being exceeded in exposure times of 20, 50, and 100 years. The results from the two models appear to be different, the expected ground motions from ASM were twice as high as expected from LSM. This difference is due to the load of the Aswan reservoir (Nasser Lake) triggering earthquakes on those parts of the faults that lie under the lake at Kalabsha area. The hazard at the selected sites is given by the hazard curve that is represented by the relationship between the peak ground acceleration and its annual exceedance probability. By comparing the curves for the six individual sites for the same source model, it can be concluded that the potential ground acceleration level for all the sites is almost the same. Considering the mean results from the two models, the annual exceedance probability of the expected ground acceleration from ASM is approximately ten times higher than the annual exceedance probability from LSM.Since ASM is based on current seismicity, it is more appropriate forrepresenting the actual hazard for the dam site. 相似文献
8.
We present some preliminary results on different mathematical problems encountered in attempts to reconstruct the coronal magnetic field, assumed to be in a force-free state, from its values in the photosphere. We discuss the formulations associated with these problems, and some new numerical methods that can be used to get their approximate solutions. Both the linear constant- and the nonlinear cases are considered. We also discuss the possible use of dynamical 3D MHD codes to construct approximate solutions of the equilibrium force-free equations, which are needed for testing numerical extrapolation schemes. 相似文献
9.
J. J. Aly 《Solar physics》1987,111(2):287-296
We consider a simple model in which the coronal magnetic field B is assumed to be potential in the region between the solar surface
o
and an exterior source-surface 1 of arbitrary shape. We prove that the boundary value problem that determines B from the value B
lof its component on
0 along either
(orthoradial direction) or
(fixed direction) has at most one solution. On the other hand, we show that a solution can exist only if B
lsatisfies some solubility conditions. 相似文献
10.
On the reconstruction of the nonlinear force-free coronal magnetic field from boundary data 总被引:1,自引:0,他引:1
J. J. Aly 《Solar physics》1989,120(1):19-48
Using a simple model in which the corona is represented by the half-space domain = {z > 0} and the photosphere by the boundary plane = {z = 0}, we discuss some important aspects of the general problem of the reconstruction of the magnetic field B in a small isolated coronal region from the values of the vector B¦
measured by a magnetograph over its whole basis. Assuming B to be force-free in : (i) we derive a series of relations which must be necessarily satisfied by the boundary field B¦
, and then by the magnetograph data if the force-free assumption is actually correct; (ii) we show how to extract directly from the measured B¦
some useful informations about the energy of B in and the topological structure of its field lines; (iii) we present a critical discussion of the two methods which have been proposed so far for computing effectively B in from B¦
. 相似文献