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661.
P. K. Das 《Journal of Astrophysics and Astronomy》1997,18(4):435-440
The variable Mass Hypothesis of conformal gravitation theory of Hoyle-Narlikar is used to develop a model for the anomalous
redshift quasar-galaxy associations. It is hypothesised that quasars are born in and ejected from the nuclei of parent galaxies
as massless objects and the particle masses in them systematically increase with epoch. The dynamics of such an ejection is
discussed and it is shown that the observed features such as redshift bunching and quasar alignments can be understood in
this scenario. Further tests of this hypothesis are suggested. 相似文献
662.
Summary. In an earlier work, mathematical formulation on computing the electromagnetic response of an arbitrarily shaped three-dimensional inhomogeneity in a layered earth had been worked out using an integral equation technique. The method has been used to show its efficacy by computing numerical results. Introducing suitable changes of variables the secondary contributions to Green's dyadic are put in the form of convolution integrals and are computed using a digital linear filtering scheme. The matrix equation is solved for the unknown electric fields in the inhomogeneity. The scattered fields are then calculated at the surface of the Earth using the appropriate Green's dyadic. The performance of the computations has been shown by comparing the numerical results with those obtained by analogue modelling as well as by other numerical schemes. The use of digital linear filtering saves an enormous amount of computer time.
The effects of varying excitation-frequency, conductivity of the host medium and that of the overburden have been studied in detail for a horizontal loop system traversing over a two-layered earth with a prismatic inhomogeneity situated in the lower conducting half space. 相似文献
The effects of varying excitation-frequency, conductivity of the host medium and that of the overburden have been studied in detail for a horizontal loop system traversing over a two-layered earth with a prismatic inhomogeneity situated in the lower conducting half space. 相似文献
663.
664.
D. K. Das 《Environmental Geology》1987,10(2):103-104
During the course of groundwater exploration in the upper catchment of Betwa River basin in Madhya Pradesh, Central India,
marsh gas at a depth of 171.33 m below ground level (bgl) has been observed bubbling out of the flowing water. The results
of gas analysis reveal the presence of 88% methane and 2.08% helium. Water is of sodium chloride type and possesses a high
concentration of fluoride and low concentrations of nitrate and sulphate. Tritium analysis of deep groundwater indicates a
value of 2.8 T.U., indicating pre-1953 storage with possible traces of modern contamination, which may have been introduced
during well construction. It is believed that an occurrence of marsh gas in Deccan Traps has not been reported earlier. 相似文献
665.
The geological formations that occur around Sagar consist of Upper Rewa quartzitic sandstones of Vindhvan age and nine Deccan Trap flows with three main inter-trappean bands. Most of the villages around Sagar depend upon the flow No. 5 for their water supplies. This flow forms valleys which may occur either in between the Vindhyan hills or Vindhyan hills and Trap hills, or Trap hills. To evaluate the geo-hydrological conditions of this flow under different topographic and stratigraphic controls, detailed geologic, water-shed and water table maps were prepared and analysed, after taking into consideration rain fall data for a period of sixty years. The villages selected for studies include the farm-lands of Richonda which occur in between the Vindhyan hills and Kudari, which occurs in between the Trap and Vindhyan hills. Villages like Patkui and Bhainsa, occurring on either side of the surface water divide of the same flow, are also taken into consideration. Water table maps for these villages were prepared once before the onset of rains and the second time immediately after the rains, on a scale of 16″ to a mile at 1 foot contour intervals. From such studies made on this flow, the following conclusions have been arrived at:
- Where a flow occurs in adjacent Deccan Trap valleys separated by a long continuous Vindhyan ridge, the Vindhyan ridge may act as an underground barrier, separating the ground water body of the flow into two distinct units, and the upper unit may give rise to springs on that valley side of the Vindhyan having the lower elevation.
- Where the Vindhyan ridge loses its height and disappears below the flow, the adjacent separate water bodies of this flow merge into a single water body. The portion of the Vindhyan ridge that occurs below the ground still continues to act as barrier for the water bodies of the lower flows.
- Where the flow occurs over a large area, but at places is overlaid by younger flows, giving rise to hills with distinct water-shed characteristics, the water body of the flow is generally continuous on either side of the hills, immediately after the rains. This, however, gets disrupted into separate water bodies during summer months and it is found to recede in the slope direction; nevertheless, the trend of recession is controlled locally by the levels at which the porous zone of a flow occurs.
- Where the continuity of the flow is disrupted due to denudation, producing valleys, the continuity of the water table of that flow is also interrupted.
- On either side of a distinct surface water divide of a flow, the ground water bodies occur as separate units in the flow.
666.
S. R. Das Gupta Chitta Ranjan Nayak Santanu Das Gupta 《Astrophysics and Space Science》1984,103(2):271-284
The present paper contains extensive tables of the values of theH-functionH(z,<0) and of the moments ofQ(x) (in terms of which the moments ofH(z, ) can be determined) appropriate for transfer of radiation in active amplifying media in which<0. These values have been computed correct to the 7th decimal place for values of in the range (–10–12)-(–1030) and for values of z[0,1] with the aid of a 48-point gaussian quadrature formula. 相似文献
667.
We have considered an ionospheric plasma model that includes the thermal effect along with the newly born ionic effect and derived a group travel time for the low-frequency whistlers with a view to employing it as a diagnostic tool in the ionosphere. The mathematical development shows that the thermal effect contribution varies with (
i
– )–7/2 whereas that of the newly born ionic effect varies with
i
– )–5/2. Both the effects are discussed separately. It is concluded that the effects are reasonably countable in the ionosphere. The investigations finally conclude that both the effects should be taken into the whistler waves, otherwise the method might cause a discrepancy in the results, which could affect their accuracy. 相似文献
668.
K. K. Das Shirish A. Ravan S. K. Negi Abhineet Jain P. S. Roy 《Journal of the Indian Society of Remote Sensing》1996,24(1):33-42
Rajaji National Park in U.P. is a protected area where large number of nomad population live within the park area. Their dependence on the forest for cattle rearing and firewood has caused degradation of the forests. Proximity to settlements outside the park further adds to the problems. In the present study, forest cover and river, bed changes have been attempted by using temporal aerospace data of the year 1960 and 1993. Subsequently, PAMAP GIS package has been used for the change detection analysis. The study indicates that the land cover changes are mainly due to biotic factors. Some of the important changes in forest cover are: (i) transformation of mixed forest to scrub forest in 67 ha (ii) the sal mixed and mixed sal forest categories have replaced sal forest in 262 ha (iii) significant increase in forest plantation i.e. 2075 ha in the year 1960 to 3793 ha in 1993 (iv) eighteen times increase in Chirpine area, it increased from 13 ha in 1960 to 230 ha in 1993. The land cover changes in 6663 ha (45%) out of 14962 ha of the study area. The consequential changes in the river beds due to the change in the forest cover was also analyzed. During this period river beds with boulders have increased by 87 ha. These river bed changes include lengthening and broadening of river and change in river course. 相似文献
669.
Sediment and heavy metal accumulation in the Cauvery basin 总被引:2,自引:0,他引:2
Eleven cores were collected from the Cauvery basin. Radiometric dates were used to determine modern sediment accumulation rates. Sediment accumulation rates ranged from 0.4 to 4 mm yr–. Heavy metal concentration decreases with the increase of depth. The heavy metal concentrations at certain depths are attributed to the irregular input of metals and their remobilization. Heavy metal accumulations have been computed using sediment accumulation rates, and accumulation rates show an additional anthropogenic input of metals and sediments in the recent past. Factor analysis and correlation analysis show the diverse source and accumulation mechanism influencing the metal distribution in the basin. 相似文献
670.
An instability associated with the magnetosonic wave driven unstable due to coupling with electron and ion drift modes has been considered as a potential source for driving the hydromagnetic turbulence observed in Giacobini-Zinner (G-Z) Cometary plasma. The instability has good growth rate for propagation perpendicular to plasma inhomogeneities and exists for all wave numbers. The wave period for waves propagating perpendicular to the gradients is about a few times ion-gyroperiod and higher values of plasma beta (
e
lead to stronger instability. 相似文献