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81.
K. S. Guruge P. Goswami I. Watanabe S. Abeykoon V. P. Prabhasankar K. R. Binu D. I. Joshua K. Balakrishna M. Akiba N. Munuswamy 《International Journal of Environmental Science and Technology》2017,14(1):1-18
The concentrations of 27 major and trace elements are determined in surface water samples collected from 48 sites of diverse waterways in four states (Tamil Nadu, Kerala, Karnataka, and Telangana) of South India. The aims of this study are to identify the element distribution, comparatively assess the pollution risk, and evaluate human health risks related to diverse waterways in the study area. The results indicate that elements such as Cr, Se, As, Fe, and Mn are the major pollutants, as their concentrations exceeded the acceptable national and international water quality standards in several sites of Ennore, Adyar, Cooum, Periyar, and Vrishabhavathi rivers. Furthermore, statistical analysis reveals that the Ennore, Adyar, Cooum, Periyar, and Kaveri river basins are affected by various anthropogenic activities, leading to moderate-to-high pollution by As, Cr, Mn, Fe, and Se. Potential pollution sources are industrial waste, sewage intrusion, paint industry waste, and automobile runoff. Overall, the investigated sites are categorized into three major groups: highly, moderately, and least polluted. Risk on human health by metals is then evaluated using hazard quotients (HQs) and carcinogenic risk evaluation; the results indicated that As with HQ >1 is the most hazardous pollutant, which could lead to non-carcinogenic and carcinogenic concerns, particularly in children. This study helps in establishing pollutant loading reduction goal and the total maximum daily loads and consequently contributes to preserving public health and developing water conservation strategies. 相似文献
82.
B. N. Goswami 《Journal of Earth System Science》1985,94(3):219-235
A zonally averaged version of the Goddard Laboratory for Atmospheric Sciences (GLAS) climate model is used to study the sensitivity of the northern hemisphere (NH) summer mean meridional circulation to changes in the large scale eddy forcing. A standard solution is obtained by prescribing
the latent heating field and climatological horizontal transports of heat and momentum by the eddies. The radiative heating
and surface fluxes are calculated by model parameterizations. This standard solution is compared with the results of several
sensitivity studies. When the eddy forcing is reduced to 0.5 times or increased to 1.5 times the climatological values, the
strength of the Ferrel cells decrease or increase proportionally. It is also seen that such changes in the eddy forcing can
influence the strength of theNH Hadley cell significantly. Possible impact of such changes in the large scale eddy forcing on the monsoon circulation via
changes in the Hadley circulation is discussed. Sensitivity experiments including only one component of eddy forcing at a
time show that the eddy momentum fluxes seem to be more important in maintaining the Ferrel cells than the eddy heat fluxes.
In the absence of the eddy heat fluxes, the observed eddy momentum fluxes alone produce subtropical westerly jets which are
weaker than those in the standard solution. On the other hand, the observed eddy heat fluxes alone produce subtropical westerly
jets which are stronger than those in the standard solution. 相似文献
83.
84.
Pratibha Thakuria Das Liagi Tajo Jonali Goswami 《Journal of the Indian Society of Remote Sensing》2009,37(2):317-324
Orange orchards of Meghalaya are small in size and are found together with other plants on the slopes of hills. It is also
reported that the productivity of orchards is declining in some parts of the state. Therefore in this study, we have attempted
to map areas prone to citrus productivity decline based on the integrated effect of soil erosion, vegetation condition and
moisture stress. It is difficult to identify orchards on hilly terrain using standard FCC of IRS-P6 LISS III data. Hence,
an enhanced color composite image was prepared from three images generated from indices namely SBI, NDWI and NDVI. This enhanced
color image was classified using the maximum likelihood classification method and enabled identifying villages prone to citrus
decline. The study shows that orchards of 29 villages which are suffering from moisture stress and mostly located on steep
slopes that cause heavy soil loss leading to nutrient imbalances are prone to citrus decline. These data will be useful in
mapping potential citrus decline areas over zones having similar climatic conditions so that the concerned state horticulture/agriculture
departments and citrus growers can take necessary remedial actions. 相似文献
85.
Shreerup Goswami Kamaljyoti Das Mrutyunjaya Sahoo Soumyaranjan Bal Sanghamitra Pradhan Kamal Jeet Singh Anju Saxena 《Arabian Journal of Geosciences》2018,11(17):524
The present megafloral assemblage recorded from the Barakar sediments of Dholpahar section along Singda rivulet near Gopal Prasad Village in Talcher Basin comprises of equisetaceous stems, Gangamopteris buriadica, Palaeovittaria kurzii and 19 species of the genus Glossopteris. Record of Gangamopteris, Palaeovittaria and many narrow mesh forms of Glosspteris viz., G. angustifolia, G. churiensis, G. communis, G. recurva, G. spatulata, G. stenoneura, G. tenuifolia, G. vulgaris and G. zeilleri from two older fossiliferous horizons demonstrates that these fossils were preserved during Lower Barakar sedimentation. The report of middle and broad mesh forms of Glossopteris viz., G. barakarensis, G. browniana, G. indica, G. intermittens, G. karharbariensis, G. nakkarea, G. oldhamii, G. taeniensis and G. retifera in the youngest fossiliferous horizons reveals that these fossils were preserved during the deposition of Upper Barakar sediments. The continuation of some of the Karharbari plant fossils in the early phase of Barakar Formation and their disappearance in the flora of Late Barakar suggests a shift in the climatic setup. Palaeoclimate and palaeovegetation of this area are also summarised in this study. Moreover, the fossil assemblages of different fossiliferous beds of Dholpahar section demonstrate the evolution of midrib and meshes in different reticulate leaves. 相似文献
86.
N. B. W. Harris M. Caddick J. Kosler S. Goswami D. Vance A. G. Tindle 《Journal of Metamorphic Geology》2004,22(3):249-264
A combined metamorphic and isotopic study of lit‐par‐lit migmatites exposed in the hanging wall of the Main Central Thrust (MCT) from Sikkim has provided a unique insight into the pressure–temperature–time path of the High Himalayan Crystalline Series of the eastern Himalaya. The petrology and geochemistry of one such migmatite indicates that the leucosome comprises a crystallized peraluminous granite coexisting with sillimanite and alkali feldspar. Large garnet crystals (2–3 mm across) are strongly zoned and grew initially within the kyanite stability field. The melanosome is a biotite–garnet pelitic gneiss, with fibrolitic sillimanite resulting from polymorphic inversion of kyanite. By combining garnet zoning profiles with the NaCaMnKFMASHTO pseudosection appropriate to the bulk composition of a migmatite retrieved from c. 1 km above the thrust zone, it has been established that early garnet formed at pressures of 10–12 kbar, and that subsequent decompression caused the rock to enter the melt field at c. 8 kbar and c. 750 °C, generating peritectic sillimanite and alkali feldspar by the incongruent melting of muscovite. Continuing exhumation resulted in resorption of garnet. Sm–Nd growth ages of garnet cores and rim, indicate pre‐decompression garnet growth at 23 ± 3 Ma and near‐peak temperatures during melting at 16 ± 2 Ma. This provides a decompression rate of 2 ± 1 mm yr?1 that is consistent with exhumation rates inferred from mineral cooling ages from the eastern Himalaya. Simple 1D thermal modelling confirms that exhumation at this rate would result in a near‐isothermal decompression path, a result that is supported by the phase relations in both the melanosome and leucosome components of the migmatite. Results from this study suggest that anatexis of Miocene granite protoliths from the Himalaya was a consequence of rapid decompression, probably in response to movement on the MCT and on the South Tibetan detachment to the north. 相似文献
87.
T K Goswami D Bezbaruah Soumyajit Mukherjee R K Sarmah S Jabeed 《Journal of Earth System Science》2018,127(6):88
The Neogene–Quaternary Siwalik foreland fold and thrust belt is studied for better understanding of tectonics along the Kameng river section of Arunachal Pradesh, India. The Kimi, Dafla, Subansiri, and the Kimin Formation correspond to Lower, Middle and Upper Siwaliks, respectively. The lithology in the foreland basin is dominantly sandstones, siltstones, claystones, carbonaceous shales, and boulder beds in the upper part. The structural style of the sedimentary sequence from the Main Boundary Thrust southward shows first order ramp-flat geometry. The brittle shear transfers slip across glide horizons to shallower depth. Repeated splay generations from a major regional-scale floor transfers slip from one glide horizon to another that shortens and thickens the crust. In the micro-scale, the lithological response in the structural development is well documented as pressure solution seams and other diagenetic deformation signatures. The basement asperity plays a significant role as the moving thrust front produced a major lateral ramp. The differential movement of the mountain front on both sides of the ramp is decipherable. This is especially true at the western part of the SE flowing Kameng river. The tectonic evolution of the area initiated with slip along the MBT \(\sim \)11 Ma ago along with the deposition of the Siwalik sediments. With southward propagation of the mountain front, the foreland basin shifted towards S, produced splay thrusts from the Himalayan Frontal Thrust-1 (HFT-1), which has been uplifting the Kimin and the older terraces. 相似文献
88.
We have studied the synthesis of26Al during combined hydrogen and helium-burning processes in high temperature and density conditions. The possible sites for these processes are believed to be the neutron star surfaces where the density ranges from =104–107 g cm–3 and temperature range from 108–8×108 K. The screening effect which leads to an enhancement of nuclear reaction rates is taken into account whenever necessary. A detailed calculation of the abundances of26Al and27Al isotopes is presented here. Finite amounts of26Al is found to be produced atT=2×108 K and =108 g cm–3 due to these combined reactions. This situation is likely to be realized during the -ray burst events on neutron star surface. The amount of material processed in the burst sources is very little compared to the amount of material processed in Novae or Supernovae. Thus it is suggested that rather than contributing to the overall amount of26Al, -ray bursts are likely to contribute more significantly to the inhomogeneity of26Al distribution in interstellar medium. 相似文献
89.
A semi-empirical approach has been used to obtain an analytical expression for the annealing of charged particle tracks in minerals as a function of time and temperature. The new formalism allows quantitative evaluation of the extent of annealing in samples for any specified temperature and track production history. The validity of the present approach depends upon the applicability of the Arrhenius equation to the process of annealing of nuclear tracks in solids. Laboratory track annealing studies confirm the predictive aspects of the present approach and also the applicability of Arrhenius' equation to track annealing over a wide time-temperature range (5 seconds/1200 K to 5 × 106 seconds/500 K). The present quantitative treatment of track annealing in rock minerals should permit an in-depth study of a variety of problems in meteoritics and earth sciences. 相似文献
90.
Experimental and analytical procedures devised for measurement of rare earth element (REE) abundances using a secondary ion
mass spectrometer (ion microprobe) are described. This approach is more versatile than the conventional techniques such as
neutron activation analysis and isotope dilution mass spectrometry by virtue of its high spatial resolution that allows determination
of REE abundances in small domains (10-20 micron) within individual mineral phases. The ion microprobe measurements are performed
at a low mass-resolving power adopting the energy-filtering technique (Zinner and Crozaz 1986) for removal and suppression
of unresolved complex molecular interferences in the REE masses of interest. Synthetic standards are used for determining
various instrument specific parameters needed in the data deconvolution procedure adopted for obtaining REE abundances. Results
obtained from analysis of standards show that our ion microprobe may be used for determining REE abundances down to ppm range
with uncertainties of ∼ 10 to 15%. Abundances of rare earth and several other refractory trace elements in a set of early
solar system objects isolated from two primitive carbonaceous chondrites were determined using the procedures devised by us.
The results suggest that some of these objects could be high temperature nebular condensates, while others are products of
melting and recrystallization of precursor nebular solids in a high temperature environment. 相似文献