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排序方式: 共有310条查询结果,搜索用时 15 毫秒
281.
Electron density in a coronal hole is rediscussed using the new calculation for the Mgviii 436.62/430.47 density-sensitive theoretical line ratio and with the help of available observations. 相似文献
282.
Geohistory analysis of Bombay High region 总被引:1,自引:0,他引:1
Madan Mohan 《Marine and Petroleum Geology》1985,2(4):350-360
Geohistory diagrams have been constructed for three representative sites in the Bombay High region, Offshore West-Coast India. The model curve for 60% lithospheric injection matches the intitial part of a thermo-tectonic curve for one of the sites, where a complete Tertiary sequence is developed. The study suggests that the four Paleogene unconformities, recognised in this region, were caused by eustatic falls. A distinct phase of active subsidence occurred during the late Middle — Late Miocene, probably due to more active spreading at the Mid-Indian Ocean Ridge. 相似文献
283.
Gajanan Kapure Chandrakala KariS. Mohan Rao N.D. Rao 《International Journal of Mineral Processing》2007
The Floatex density separator (FDS) is an industrial separator and works on the principle of hindered settling where the settling rate of a particle in suspension is affected by nearby particles. This phenomenon of hindered settling has been described by various authors using the concept of particle slip velocity. The feasibility of one such slip velocity model proposed by Galvin et al. to predict the separation of chromite in a plant scale FDS was examined. Previously this model was validated only at lab scale with synthetic mixture of various density particles. In order to use this model, the feed chromite ore was characterized and quantified into different density mineral classes and their percentages were estimated by using mineralogical grain count method. The performance of FDS was then predicted using slip velocity model in terms of weight recoveries and composition of different minerals in the FDS underflow product. 相似文献
284.
Coda power characteristics of six underground nuclear explosions from two near by test sites of Novaya Zemlya are examined. It is shown that one of the events presenting a complex P waveform and distinctive coda power characteristics can be synthesised by superposition of two signals of simpler form from the same site. The relative P amplitudes of the two signals give a ratio of 0.7–1.0 and the relative delay of 0.8 sec. The modulation effect is clearly seen in band-pass filtered traces where a shift in the envelope maximum occurs for center frequencies between 0.6 and 0.8 Hz. The complex event is interpreted as a double explosion. 相似文献
285.
Electrical conductivity of nineteen samples of the Deccan Traps, collected from the Pawagarh area and two boreholes drilled at Koyna, has been measured in the temperature range from 475 K to about 1100 K. The results indicate the change of the conduction mechanism from impurity to electronic/ionic conduction as the temperature increases. Few samples show the normal behaviour, i.e. the increase of conductivity with temperature, while some samples show an anomalous behaviour between the temperatures 600 and 1000 K. This anomalous behavior may be due to either the dehydration of OH? ions or/and the oxidation of Fe2+ to Fe3+. 相似文献
286.
SIR-B Synthetic Aperture Radar System operating at L-band (HH) acquired images over parts of the Assam plains at 25.6° and 45.2°incidence angle during October 1984. The capabilities of L-band SAR for delineating various land covers using multiple incidence angle imageries have been assessed. It was observed that colour composite image generated from multiple incidence angle imagery was useful in delineating various land cover units. 相似文献
287.
Marina Aloysius Mannil Mohan S. Suresh Babu Vijayakumar S. Nair K. Parameswaran K. Krishna Moorthy 《Journal of Earth System Science》2008,117(1):353-360
MODIS (Moderate Resolution Imaging Spectroradiometer) level-3 aerosol data, NCEP (National Centers for Environmental Prediction) reanalysis winds and QuikSCAT ocean surface winds were made use of to examine the role of atmospheric circulation in governing aerosol variations over the Bay of Bengal (BoB) during the first phase of the ICARB (Integrated Campaign for Aerosols, gases and Radiation Budget) campaign (March 18–April 12, 2006). An inter-comparison between MODIS level-3 aerosol optical depth (AOD) data and ship-borne MICROTOPS measurements showed good agreement with correlation 0.92 (p < 0.0001) and a mean MODIS underestimation by 0.01. During the study period, the AOD over BoB showed high values in the northern/north western regions, which reduced towards the central and southern BoB. The wind patterns in lower atmospheric layers (> 850 hPa) indicated that direct transport of aerosols from central India was inhibited by the presence of a high pressure and a divergence over BoB in the lower altitudes. On the other hand, in the upper atmospheric levels, winds from central and northern India stretched south eastwards and converged over BoB with a negative vorticity indicative of a downdraft. These wind patterns pointed to the possibility of aerosol transport from central India to BoB by upper level winds. This mechanism was further confirmed by the significant correlations that AOD variations over BoB showed with aerosol flux convergence and flux vorticity at upper atmospheric levels (600–500 hPa). AOD in central and southern BoB away from continental influences displayed an exponential dependence on the QuikSCAT measured ocean surface wind speed. This study shows that particles transported from central and northern India by upper atmospheric circulations as well as the marine aerosols generated by ocean surface winds contributed to the AOD over the BoB during the first phase of ICARB. 相似文献
288.
Enrichment of trace metals in surface sediments from the northern part of Point Calimere, SE coast of India 总被引:1,自引:0,他引:1
V. Stephen-Pichaimani M. P. Jonathan S. Srinivasalu N. Rajeshwara-Rao S. P. Mohan 《Environmental Geology》2008,55(8):1811-1819
This study deals with the geochemical nature of distribution, enrichment of total trace metals (Fe, Mn, Cr, Cu, Ni, Co, Pb,
Zn, Cd) in bulk sediments and its association with sediment texture, carbonates and organic carbon. Sixty surface sediment
samples were collected during two different seasons in 2002 and 2003 along the coastal regions in three transects from Nagapattinam
town, north of Point Calimere in southeast coast of India. The sediments are mostly sandy silt and are dominated by the carbonate
content. Organic carbon distribution indicates that they are brought in by the minor river input. Enrichment of trace metals
is clearly identified by the domination of Pb, Zn, Cd with high values than the average crustal values and comparison of trace
metals from other coastal regions in the southeast coast of India. Statistical analysis clearly indicates that Fe and Mn control
the distribution of trace metals and are concentrated in the finer particles and organic carbon fraction. The increase in
concentration signifies the need for regular monitoring of the offshore coastal region in southeast coast of India which was
recently destroyed by the 2004 December tsunami event, and which is also located near the Sethu Samuthram Ship Canal Project. 相似文献
289.
The number of drought events derived from the historic streamflow or rainfall series will be limited and produce results that are not very reliable. This study proposes a drought simulation methodology that uses a long sequence of synthetically generated monthly streamflow/rainfall series, from which it is possible to drive a large sample of drought events and the prediction of drought characteristics will be reliable. The modified Herbst method has been used to identify droughts in the generated streamflow and rainfall series. The drought simulation procedure is illustrated with a case study of the Bhadra reservoir catchment in Karnataka State, India. Monthly droughts were derived from both historic and generated monthly streamflow and rainfall series. The important drought characteristics were determined and the suitable probability distribution for each parameter was arrived at after studying seven different probability models. The use of the probability curves thus derived has been illustrated with examples (referred to in Part 1 as ‘point droughts’). Similarly, the development and application of stochastic models for the prediction of regional drought parameters have been illustrated with examples in the accompanying paper (Part 2: regional droughts). Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
290.