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131.
New tectonic uplifts south of the Salt Range Thrust and Himalayan Front Thrust (HFT) represent an outward step of the plate boundary from the principal tectonic displacement zone into the Indo-Gangetic Plain. In Pakistan, the Lilla Anticline deforms fine-grained overbank deposits of the Jhelum River floodplain 15 km south of the Salt Range. The anticline is overpressured in Eocambrian non-marine strata. In northwest India south of Dehra Dun, the Piedmont Fault (PF) lies 15 km south of the HFT. Coalescing fans derived from the Himalaya form a piedmont (Old Piedmont Zone) 15–20 km wide east of the Yamuna River. This zone is uplifted as much as 15–20 m near the PF, and bedding is tilted 5–7° northeast. Holocene thermoluminescence-optically-stimulated luminescence dates for sediments in the Old Piedmont Zone suggest that the uplift rate might be as high as several mm/a. The Old Piedmont Zone is traced northwest 200 km and southeast another 200 km to the Nepal border. These structures, analogous to protothrusts in subduction zones, indicate that the Himalayan plate boundary is not a single structure but a series of structures across strike, including reactivated parts of the Main Boundary Thrust north of the range front, the HFT sensu stricto, and stepout structures on the Indo-Gangetic Plain. Displacement rates on all these structures must be added to determine the local India-Himalaya convergence rate. 相似文献
132.
R. K. Thakur 《Astrophysics and Space Science》1992,190(2):281-292
Within the framework of FLRW cosmology withk=+1 a singularity free model of the Universe is proposed which readily accounts for the origin of the Big-Bang and for the preponderance of matter over anti-matter. It is also free from the problems of accounting for the observed large-scale homogeneity and isotropy of the Universe as well as from the problems of horizon and flatness. It is pointed out that the collapsing universe might have acted as an ultra-high energy particle accelerator. In the collapsing phase of the Universe, when the interparticle distances10–16 cm, the electromagnetic and weak interactions might have unified into electroweak interaction and as the collapse proceeded further the entire matter in the Universe might have been converted into quark-gluon plasma permeated by leptons. The gravitational energy released during the collapse might have been locked in this plasma. Ass approached 10–28 cm, grand unification of electroweak and strong interactions might have occurred. It is also suggested that, with further collapse, whens<10–33 cm super-symmetry (SUSY)—i.e., the unification of all the four interactions (viz., electromagnetic, weak, strong, and gravitational) might have occurred. During this process gravitinos, the supersymmetric partners of graviton might have been produced. As a result of the exchange of a pair of virtual gravitinos between two particles an ultra-strong repulsive force between them might have been generated. Due to this ultra-strong repulsive interaction between particles the motion of the Universe might have been reversed, i.e., the Universe might have started expanding. During expansion, whens10–28 cm, SUSY might have broken down spontaneously toSU
5 and gravity. Ass increased from 10–28 to 10–16 cm, the gravitational energy locked in the quark-gluon plasma might have been released with a gigantic explosion, the so-called Big-Bang. It is estimated here that during this Big-Bang more than 1082 GeV of energy might have been released. Whens10–16 cm,SU
5 might have broken down spontaneously toSU
3 andU
1. Expansion beyond this stage might have occurred in the manner described by the standard cosmology. It is further suggested that in due course of time expansion will be followed by contraction and the cycle of contraction-expansion-contraction will be repeated ad infinitum. 相似文献
133.
The integral balance method has been used to obtain an approximate analytical solution of a nonlinear boundary value problem which arises in the theory of diffusion with a concentration-dependent coefficient. It is the purpose of this paper to give an interpretation of the supposition of interface reactions which obey the law of kinetic mass action.Nomenclature
C(Z,t)
concentration
-
C
0
concentration at initial time
-
D
diffusivity
-
D
0
diffusivity at initial time
-
F(t)
a function of time
-
K
0
half-order reaction rate constant
-
k
1
first-order reaction rate constant
-
k
2
second-order reaction rate constante
-
L
characteristic length
-
n
parameter
-
t
time
-
Z
space variable
Dimensionless variables and similarity criteria
nondimensional half-order reaction rate constant
-
nondimensional first-order reaction rate constant
-
nondimensional second-order reaction rate constant
-
x=Z/L
dimensionless space variable
-
F
0=D
0
t/L
2
Fourier number
-
g(F
0)=[F(t)–C
0]/C
0
a function of generalized time
- (x, F
0)=[C(x,t)–C
0]/C
0
dimensionless concentration
- <(F
0)>
dimensionless average concentration 相似文献
134.
Naresh Kumar Thakur Pasupuleti Prasada Rao N. Vishwanath Sanjeev Rajput Bhaskarabhatla Ashalatha 《Marine Geophysical Researches》2007,28(4):373-378
Seismic tomography is an effective means of estimating velocity and structure from multichannel seismic (MCS) reflection data.
In this study we have followed a 2D approach to arrive at the probable velocity field configuration from multichannel seismic
data and infer the presence of gas hydrates/free-gas in the offshore Kerala-Konkan region, along the eastern part of a seismic
line on which a bottom simulating reflector (BSR) has previously been identified. Tomographic modeling consists of the identification
of reflection phases and picking of respective travel times for various source-receiver positions. These picks were then utilized
to arrive at a 2D velocity field following a forward and inversion approach using a ray tracing technique. The modeling for
the first time brought out the finer scale velocity structure under the region of investigation. Modeling through the 2D approach
shows lateral variation in velocity field along the studied segment of the seismic line. The results indicate a thin (∼50–60 m)
sedimentary cover with velocity ranging from 1,770 to 1,850 m/s. A sedimentary layer with high P-wave velocity 1,980–2,100 m/s
below the sea floor was interpreted as the hydrate layer. The thickness of this layer varies between 110 and 140 m. The hydrate
layer is underlain by a low-velocity layer having velocities in the range 1,660–1,720 m/s. This low velocity may represent
a free gas layer, whose thickness varies between 50 and 100 m located below the hydrated layer. The investigation suggests
the occurrence of gas hydrate underlain by free gas in some parts of the Kerala-Konkan offshore region. 相似文献
135.
In seismic sections, the presence of a gas hydrate stability zone (GHSZ) is often marked by a bottom-simulating reflector, which has a negative polarity with respect to the seafloor. The present study reveals the response of seismic wave characteristics and amplitude versus offset (AVO) effects of large offset compressional (P) and converted (PS) waves for a GHSZ/free-gas configuration, using a two-dimensional elastic anisotropic modelling technique. The modelling results would provide a priori information, which allows unique determination of parameters of seismic models for the design of ocean bottom seismometer experiments over continental margins for the purpose of gas hydrate exploration. The AVO analyses on long offset P and PS waves based on synthetic data yield a typical gas hydrate/free-gas response, as the reflectivity increases with incidence angle. 相似文献
136.
Use of fuzzy synthetic evaluation for assessment of groundwater quality for drinking usage: a case study of Southern Haryana,India 总被引:1,自引:0,他引:1
Bhupinder Singh Sudhir Dahiya Sandeep Jain V. K. Garg H. S. Kushwaha 《Environmental Geology》2008,54(2):249-255
A method based on concept of fuzzy set theory has been used for decision-making for the assessment of physico-chemical quality
of groundwater for drinking purposes. Conventional methods for water quality assessment do not consider the uncertainties
involved either in measurement of water quality parameters or in the limits provided by the regulatory bodies. Fuzzy synthetic
evaluation model gives the certainty levels for the quality class of the water based on the prescribed limit of various regulatory
bodies and opinion of the experts from the field of drinking water quality. In this paper, application of fuzzy rule based
optimization model is illustrated with twenty groundwater samples from Sohna town of Gurgaon district of Southern Haryana,
India. These samples were analysed for 15 different physico-chemical parameters, out of them nine important parameters were
used for the quality assessment using fuzzy synthetic evaluation approach. From this study, it has been concluded that all
the water samples are in acceptable category whose certainty level ranges from 44 to 100%. Water from these sources can be
used for the drinking purposes if alternate water source is not available without any health concern on the basis of physico-chemical
characteristics. 相似文献
137.
138.
The present study deals with the seasonal variation of temperature, alkalinity and dissolved oxygen in the Sagar lake. Different abiotic and biotic factors were investigated and a diurnal study was made, too. The investigation shows that the surface water values were always higher than the bottom water values. The water temperature ranged from 16.0 to 31.0 °C, carbonate alkalinity ranged from 0.0 to 46.0 mg/1, bicarbonate alkalinity ranged from 62.0 to 138.0 mg/1, dissolved oxygen ranged between 1.6 and 13.2 ppm. The water temperature was found to be positively correlated with carbonate alkalinity while an inverse correlation existed with bicarbonate alkalinity. Dissolved oxygen had a significant positive correlation with carbonate alkalinity, while a negative correlation was observed with bicarbonate alkalinity during all the seasons. 相似文献
139.
The observed behaviour of buildings during earthquakes indicates clearly the importance of the flexibility of floor and roof diaphragms in the response of many structures. This paper presents a new analytical method for the dynamic analysis of some one- and two-storey buildings whose floors may have significant in-plane flexibility. The method begins by treating the floors as bending beams and the walls as shear beams. The equations of motion and the boundary conditions for the floors and the walls are then formulated in one coordinate system and solved exactly to obtain the characteristic equation for the system, which can be solved numerically to obtain the natural frequencies. These, in turn, can be used to determine the mode shapes of the system and the participation factors for earthquake response. Solutions are given for one- and two-storey buildings that resist lateral loads in the transverse direction by two end walls. Perturbation techniques are also applied to simplify further the determination of the fundamental frequency of such single-storey structures. To illustrate the method, a two-storey structure, the Arvin (California) High School Administration Building, damaged in the Kern County earthquake of 1952, has been analysed in its transverse direction. It is seen that the first two modes, dominated by the floor and the roof vibrations, make the largest contributions to the total base shear in the structure. 相似文献
140.
Dr. Vishwajit J. Gupta Dr. Vikram C. Thakur 《International Journal of Earth Sciences》1974,63(2):548-558
In the present paper an attempt has been made to describe the geology of the area around Dharmsala, Kangra District, Himachal Pradesh. The stratigraphic position of the problematic horizons, i. e., Dharmkot Limestone and Dharmsala Traps is discussed in detail. 相似文献