全文获取类型
收费全文 | 44篇 |
免费 | 0篇 |
专业分类
大气科学 | 1篇 |
地球物理 | 7篇 |
地质学 | 21篇 |
自然地理 | 15篇 |
出版年
2014年 | 1篇 |
2013年 | 1篇 |
2012年 | 2篇 |
2011年 | 1篇 |
2010年 | 3篇 |
2009年 | 2篇 |
2007年 | 2篇 |
2006年 | 1篇 |
2005年 | 2篇 |
2004年 | 3篇 |
2002年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1994年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1969年 | 3篇 |
1968年 | 1篇 |
1967年 | 2篇 |
1966年 | 1篇 |
排序方式: 共有44条查询结果,搜索用时 281 毫秒
31.
Sarva Jit Singh 《Journal of Earth System Science》1982,91(3):241-245
Expressions for kinetic energy, elastic potential energy and gravitational potential energy for the spheroidal oscillations
of a spherically symmetric, self-gravitating, elastic earth model have been obtained. Some inconsistencies in the expressions
given by earlier authors have been pointed out. The principle of equipartition of energy and the Rayleigh principle have been
used to derive a formula for Rayleigh wave group velocity in terms of energy integrals. This formula can be used to compute
the group velocity without the numerical differentiation implied in its definition 相似文献
32.
The correspondence principle is used to get the Laplace transformed solution of the problem of the quasi-static deformation of a viscoelastic half-space by a shear displacement dislocation from the corresponding static elastic results. The transformed solution is inverted for the Voigt and the Maxwell viscoelastic models. It is shown that, for a vertical dip-slip fault, the surface displacements for the viscoelastic case are identical with the elastic displacements. In the case of a vertical strike-slip fault, detailed numerical results are obtained for both a point source and a finite rectangular source. It is found that the results for the viscoelastic models differ significantly from the corresponding elastic results. 相似文献
33.
Closed-form expressions for the displacements and stresses at any point of either of two elastic half-spaces in welded contact caused by a dip-slip line source obtained earlier are integrated analytically to derive the elastic residual field due to a long dip-slip fault of finite width. The results are valid for an arbitrary dip of the fault. The variation of the displacement field with the distance from the fault as well as with the distance from the interface is studied numerically. It is found that the displacement field is heavily dependent on the dip angle. Contour maps showing the residual elastic field in the two half-spaces caused by a vertical dip-slip fault located in one of the half-spaces are also obtained. 相似文献
34.
The problem of the coseismic deformation of an earth model consisting of an elastic layer of uniform thickness overlying an
elastic half-space due to a very long tensile fault in the layer is solved analytically. Integral expressions for the surface
displacements are obtained for a vertical tensile fault and a horizontal tensile fault. The integrals involved are evaluated
approximately by using Sneddon’s method of replacing the integrand by a finite sum of exponential terms. Detailed numerical
results showing the variation of the displacements with epicentral distance for various source locations in the layer are
presented graphically. The displacement field in the layered half-space is compared with the corresponding field in a uniform
half-space to demonstrate the effect of the internal boundary. Relaxed rigidity method is used for computing the postseismic
deformation of an earth model consisting of an elastic layer of uniform thickness overlying a viscoelastic half-space. 相似文献
35.
Praveena Krishnan P. K. Kunhikrishnan S. Muraleedharan Nair Sudha Ravindran Radhika Ramachandran D. B. Subrahamanyam M. Venkata Ramana 《Journal of Earth System Science》2004,113(3):353-363
This paper discusses the observations of the Atmospheric Surface Layer (ASL) parameters during the solar eclipse of August
11th, 1999. Intensive surface layer experiments were conducted at Ahmedabad (23‡21′N, 72‡36′E), the western part of India,
which was close to the totality path. This rare event provided by nature is utilised to document the surface layer effects
during the eclipse period using measurements of high frequency fluctuations of temperature, tri-axial wind components as well
as mean parameters such as temperature, humidity, wind speed and subsoil temperature. Analysis showed that during the eclipse
period, the turbulence parameters were affected leading to the suppression of the turbulence process, the main dynamic process
in the atmospheric boundary layer, while the mean parameters showed variations within the natural variability of the observational
period. The spectra of the wind components and temperature indicated decrease in spectral power by one order in magnitude
during the eclipse period. The rate of dissipation of turbulent kinetic energy is found to decrease by more than one order
during the eclipse period. The stability parameter showed a change from unstable to stable condition during the period of
eclipse and back to unstable condition by the end of eclipse 相似文献
36.
Summary An explicit solution is obtained for the system of equations describing the spheroidal motion in a homogeneous, isotropic, gravitating, elastic medium possessing spherical symmetry. This solution is used to derive the Green's dyad for a homogeneous gravitating sphere. The Green's dyad is then employed to obtain the displacement field induced by tangential and tensile dislocations of arbitrary orientation and depth within the sphere.Notation
G
Gravitational constant
-
a
Radius of the earth
-
A
o
=4/3 G
-
Perturbation of the gravitational potential
-
Circular frequency
-
V
p
,V
s
Compressional and shear wave velocities
-
k
p
=/V
p
-
k
s
=/V
s
-
k
p
[(2.8)]
- ,
[(2.17)]
-
f
l
+
Spherical Bessel function of the first kind
-
f
l
–
Spherical Hankel function of the second kind
-
x
=r
-
y
=r
-
x
o
=r
o
-
y
o
=ro
-
x
=r k
s
-
y
=r k
p
-
x
o
=r
o
k
s
-
y
o
=r
o
k
p
-
=a
-
=a
-
[(5.17)]
-
m, l
相似文献
37.
38.
Sarva Jit Singh Gulshan Kumari & Kuldip Singh 《Geophysical Journal International》1999,139(2):591-596
Closed-form analytical expressions for the displacements and stresses induced by a single force of arbitrary orientation located in an elastic half-space in welded contact with another elastic half-space are obtained. These expressions are valid for arbitrary values of the Poisson's ratio and for arbitrary source and observer locations. The final results are given in a form that makes numerical computation straightforward and accurate. 相似文献
39.
Consolidation of a poroelastic half-space with anisotropic permeability and compressible constituents by axisymmetric surface loading 总被引:1,自引:0,他引:1
The fully coupled Biot quasi-static theory of linear poroelasticity is used to study the consolidation of a poroelastic half-space
caused by axisymmetric surface loads. The fluid and solid constituents of the poroelastic medium are compressible and its
permeability in the vertical direction is different from its permeability in the horizontal direction. An analytical solution
of the governing equations is obtained by taking the displacements and the pore pressure as the basic state variables and
using a combination of the Laplace and Hankel transforms. The problem of an axisymmetric normal load is discussed in detail.
An explicit analytical solution is obtained for normal disc loading. Detailed numerical computations reveal that the anisotropy
in permeability as well as the compressibilities of the fluid and solid constituents of the poroelastic medium have significant
effects on the consolidation of the half-space. The anisotropy in permeability may accelerate the consolidation process and
may lead to a dilution in the theoretical prediction of the Mandel-Cryer effect. The compressibility of the solid constituents
may also accelerate the consolidation process. 相似文献
40.
Chin Yik Lin Mohd. Harun Abdullah Baba Musta Sarva Mangala Praveena Ahmad Zaharin Aris 《Natural Resources Research》2011,20(1):45-56
A total of 20 soil samples were collected from 10 boreholes constructed in the low lying area, which included ancillary samples
taken from the high elevation area. Redox processes were investigated in the soil as well as groundwater in the shallow groundwater
aquifer of Manukan Island, Sabah, Malaysia. Groundwater samples (n = 10) from each boreholes were also collected in the low lying area to understand the concentrations and behaviors of Fe
and Mn in the dissolved state. This study strives to obtain a general understanding of the stability behaviors on Fe and Mn
at the upper unsaturated and the lower-saturated soil horizons in the low lying area of Manukan Island as these elements usually
play a major role in the redox chemistry of the shallow groundwater. Thermodynamic calculations using PHREEQC showed that
the groundwater samples in the study area are oversaturated with respect to goethite, hematite, Fe(OH)3 and undersaturated with respect to manganite and pyrochroite. Low concentrations of Fe and Mn in the groundwater might be
probably due to the lack of minerals of iron and manganese oxides, which exist in the sandy aquifer. In fact, high organic
matters that present in the unsaturated horizon are believed to be responsible for the high Mn content in the soil. It was
observed that the soil samples collected from high elevation area (BK) comprises considerable amount of Fe in both unsaturated (6675.87 mg/kg) and saturated horizons (31440.49 mg/kg) compared
to the low Fe content in the low lying area. Based on the stability diagram, the groundwater composition lies within the stability
field for Mn2+ and Fe2+ under suboxic condition and very close to the FeS/Fe2+ stability boundary. This study also shows that both pH and Eh values comprise a strong negative value thus suggesting that
the redox potential is inversely dependent on the changes of pH. 相似文献