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91.
Anisotropic universe with cosmic strings and bulk viscosity in a scalar–tensor theory of gravitation
V. U. M. Rao G. Sree Devi Kumari K. V. S. Sireesha 《Astrophysics and Space Science》2011,335(2):635-638
A spatially homogeneous and anisotropic Bianchi type-I cosmological model is obtained in a scalar–tensor theory of gravitation
proposed by Saez and Ballester (Phys. Lett. A 113:467, 1986) when the source for energy momentum tensor is a bulk viscous fluid containing one dimensional cosmic strings. Some physical
and kinematical properties of the model are discussed. It is observed that the bulk viscosity has a greater role in getting
an accelerated expansion of the universe in this theory. 相似文献
92.
U. C. Kulshrestha A. Saxena N. Kumar K. M. Kumari S. S. Srivastava 《Journal of Atmospheric Chemistry》1998,29(2):109-118
Size-differentiated concentrations of SPM, F, Cl, NO3, SO4, Na, K, Ca, Mg and NH4 in atmospheric aerosols were measured in a suburban area of Agra city during December 1992 to March 1993. Except for NH4, Cl and Na, all components were found to have a bimodal distribution. The fine fraction was dominated by NH4, K, NO3 and SO4, while Na, Ca, Mg, F and Cl contributed to the coarse fraction. Fifty-eight percent of SO4 and 67% of NO3 were found in the fine mode and the coarse mode comprised 42 and 33% of SO4 and NO3, respectively. SO4 was found to have a peak above the submicron range at 1.1 µm which has been attributed to secondary sulphate formation by heterogeneous oxidation of SO2 on alkaline particles of Ca and Mg. The total aerosol was basic in nature and dominated by the soil-derived acid neutralising components (Ca, Mg and Na). 相似文献
93.
Soil characterization using electrical resistivity tomography and geotechnical investigations 总被引:1,自引:0,他引:1
Electrical Resistivity Tomography (ERT) has been used in association with Standard Penetration Test (SPT) and Dynamic Cone Penetration Test (DCPT) for Geotechnical investigations at two sites, proposed for thermal power plants, in Uttar Pradesh (UP), India. SPT and DCPT tests were conducted at 28 points and two ERT profiles, each measuring 355 m long, were recorded using 72 electrodes deployed at 5 m spacing. Electrical characterization of subsurface soil was done using borehole data and grain size analysis of the soil samples collected from boreholes. The concept of electrical resistivity variation with soil strength related to the grain size distribution, cementation, porosity and saturation has been used to correlate the transverse resistance of soil with the number of blow counts (N-values) obtained from SPT and DCPT data. It was thus observed that the transverse resistance of soil column is linearly related with the number of blow counts (N-values) at these sites. The linear relationships are site-specific and the coefficients of linear relation are sensitive to the lithology of subsurface formation, which was verified by borehole data. The study demonstrates the usefulness of the ERT method in geotechnical investigations, which is economic, efficient and less time consuming in comparison to the other geotechnical methods, such as SPT and DCPT, used for the purpose. 相似文献
94.
The thermosolutal-convective instability of a composite stellar atmosphere is considered in the presence of variable horizontal magnetic field and collisional effects. The criteria for monotonic instability are obtained which generalize the criterion derived for thermal-convective instability in the absence of above effects. 相似文献
95.
A. Anand Beena Kumari S. R. Nayak Y. V. N. Krishnamurthy 《Journal of the Indian Society of Remote Sensing》2005,33(4):511-520
Tuna fishery resources are currently under exploited. The resource potential of tunas in the Indian Exclusive Economic Zone
(EEZ) beyond 50 m depths is around 2.09 lakh tonnes as estimated by Fishery Survey of India. The distribution and availability
of the tuna are governed by environmental factors like temperature, thermocline depth, availability of prey, visibility etc.
Remote sensing provides synoptic information on productivity in terms of chlorophyll and Sea Surface Temperature (SST). In
the present paper, satellite remote sensing data from Indian Remote Sensing Satellite IRS- P4 Ocean Colour Monitor (OCM) sensor
for chlorophyll-a and diffuse attenuation coefficient (K) and National Oceanic and Atmospheric Administration (NOAA) - Advanced
Very High Resolution Radiometer (AVHRR) sensor data for sea surface temperature were analysed and correlated within situ catch data of oceanic tunas, Skipjack(Katsuwonus pelamis) and Yellowfin tuna(Thunnus albacares), off Maharashtra coast. Higher catches were found to be associated with moderate to good primary productivity and in the
vicinity of thermal fronts. Relationship between Hooking rate and SST has shown that SST of 28–30°C range is optimum for skipjack
and 28–31°C for yellowfin tuna. Besides satellite derived chlorophyll and SST for identification of potential tuna fishing
zones, role of diffuse attenuation coefficient (K) for visibility factor is also discussed. 相似文献
96.
The exposure of Puntius sophore to different concentrations of crude oil (200… 4000 ppm) revealed that 4000 ppm was acutely lethal to the fish and mortality did not occur at <500 ppm at 21±1 °C for up to 15 days. The increase in the opercular frequency during exposure to crude oil has been recorded almost parallel to toxicant concentrations. The objectionable odour of the crude oil and the formation of coagulated mucous film over the body and gills were the main factors causing mortality among the experimental fish. The 24, 48, 78 and 96-h TL 50 values have been 3275, 1750, 1650 and 1450 ppm. The corresponding regression coefficients b were –1.8056, –1.5849, –1.6037 and –1.6497. 相似文献
97.
Miss Santosh Kumari Wadhwa 《Pure and Applied Geophysics》1971,89(1):84-97
Summary The problem of a transiton layer lying between two homogeneous liquid media has been discussed in a previous paper. There, some of the terms in the integrands in the expressions for the displacement potentials due to a periodic point source, lying in the upper layer, have been evaluated along the Sommerfeld loops. Both first order and second order discontinuities in density and bulk modulus at the boundaries of the transition layer have been considered. In the present paper, the integrals for the displacement potentials have been evaluated by the method of stationary phase and the results obtained are compared with those obtained previously. Also the first order discontinuities in density and velocity at the two ends of the transition layer are removed and the work is extended to an explosion type pulse. It is found that for a pulse source, the decrease with distance is the same as for a periodic point source. Also the frequency dependence for the refraction arrivals, when frequency is extremely high, is 1/3 as compared to –1 in the case when there are discontinuities at the boundaries of the transition layer. 相似文献
98.
This addendum uses an alternate fit for the electron density distribution \(N(r)\) (see Figure 1) and estimates the coronal magnetic field using the new model. We find that the estimates of the magnetic field are in close agreement using both the models.
We have fit the \(N(r)\) distribution obtained from STEREO-A/COR1 and SOHO/LASCO-C2 using a fifth-order polynomial (see Figure 1). The expression can be written as where \(N_{\text{cor}}(r)\) is in units of cm?3 and \(r\) is in units of \(\mathrm{R}_{\odot}\). The background coronal electron density is enhanced by a factor of 5.5 at 2.63 \(\mathrm{R}_{\odot}\) during the coronal mass ejection (CME). The estimated coronal magnetic field strength (\(B\)) using radio data indicates that \(B(r) \approx(0.51\text{\,--\,}0.48) \pm 0.02\ \mathrm{G}\) in the range \(r \approx2.65\text{\, --\,}2.82\ \mathrm{R}_{\odot}\). The field strengths for STEREO-A/COR1 and SOHO/LASCO-C2 are ≈?0.32 G at \(r \approx 3.11\ \mathrm{R}_{\odot}\) and ≈?0.12 G at \(r \approx 4.40\ \mathrm{R}_{\odot}\), respectively.
相似文献
$$\begin{aligned} N_{\text{cor}}(r) &= 1.43 \times 10^{9} r^{-5} - 1.91 \times 10^{9} r^{-4} + 1.07 \times 10^{9} r^{-3} - 2.87 \times 10^{8} r^{-2} \\ &\quad {} + 3.76 \times 10^{7} r^{-1} - 1.91 \times 10^{6} , \end{aligned}$$
(1)