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排序方式: 共有1001条查询结果,搜索用时 921 毫秒
921.
This paper presents tsunami intensity mapping and damage patterns along the surveyed coast of Tamilnadu (India) of the deadly
Indian Ocean tsunami of December 26, 2004. The tsunami caused severe damage and claimed many victims in the coastal areas
of eleven countries bordering the Indian Ocean. A twelve-stage tsunami intensity scale proposed by Papadopoulos and Imamura
(2001) was followed to assign the intensity at the visited localities. Along the coast of the Indian mainland, tsunami damage
sustained exclusively. Most severe damage was observed in Nagapattinam Beach, Nabiyarnagar, Vellaipalyam, and the Nagapattinam
Port of Nagapattinum District on the east coast and Keelamanakudy village of Kanyakumari District on the western coast of
Tamilnadu. The maximum assigned tsunami intensity was X+ at these localities. Minimum intensity V+ was received along the coast of Thanjavur, Puddukkotai and Ramnathpuram Districts in Palk Strait. The general observation
reported by many people was that the first arrival was a tsunami crest. The largest tsunami waves were first arrivals on the
eastern coast and the second arrivals on the western coast. Along the coast, people were unaware of the tsunami, and no anomalous
behavior of ocean animals was reported. Good correlation was observed between the severity of damage and the presence of shadow
zone of Sri Lanka, reflected waves from Sri Lanka and the Maldives Islands, variation in the width of the continental shelf,
elevation of the coast and the presence of breakwaters. The presence of medu (naturally elevated landmass very close to the
sea shore and elongated parallel to the coast) reduced the impact of the tsunami on the built environment. 相似文献
922.
923.
A. K. Gupta J. R. Sharma G. Sreenivasan K. S. Srivastava 《Journal of the Indian Society of Remote Sensing》2004,32(1):1-24
Numerous studies have been carried out during last 20-25 years by different agencies to trace the courses of palaeo river
Sarasvati. Varying number of courses of river Sarasvati have been suggested by the different workers in the north-western
region. Taking advantage of the developments in satellite/ sensor and digital image processing technologies an attempt has
been made to rediscover the course of river Sarasvati and solve the controversy regarding its exact course, in the sand covered
Thar desert region. Data available from a variety of ground investigations carried out by different agencies working in this
area have been analyzed in support of confirmation of palaeo channels, along the courses mapped under the present study. The
results indicate that the river Sarasvati had its course through river Ghaggar and did not drain along the Aravalli hills.
Also it did not shift its course drastically and continuously from east to west, as suggested by earlier workers. The image
anomalies indicate that river Sarasvati flowed parallel to the river Indus as an independent river system (closer to the north-western
Indian border) and did not flow through present course of river Nara. The findings raise the doubt that ‘Rise along Delhi-Hardwar
ridge’ as suggested by earlier workers was the main cause for west-ward shift of Sarasvati river and ultimate drainage desiccation
in the northwestern region. The analysis indicates towards rise in Himalayas/ Siwaliks and consequent displacements in the
Siwaliks and its foot hills region (in the form of Yamuna and Satlej tear faults) as the main cause for drainage desiccation
and disappearance of river Sarasvati. 相似文献
924.
The Neoproterozoic Malani magmatism of the northwestern Indian shield: implications for crust-building processes 总被引:1,自引:0,他引:1
Kamal K. Sharma 《Journal of Earth System Science》2004,113(4):795-807
Malani is the largest event of anorogenic felsic magmatism (covering ∼50, 000 km2) in India. This magmatic activity took place at ∼750 Ma post-dating the Erinpura granite (850 Ma) and ended prior to Marwar
Supergroup (680 Ma) sedimentation. Malani eruptions occurred mostly on land, but locally sub-aqueous conditions are shown
by the presence of conglomerate, grits and pillow lava. The Malani rocks do not show any type of regional deformation effects.
The Malanis are characterised by bimodal volcanism with a dominant felsic component, followed by granitic plutonism and a
terminal dyke phase. An angular unconformity between Malani lavas and basement is observed, with the presence of conglomerate
at Sindreth, Diri, and Kankani. This indicates that the crust was quite stable and peneplained prior to the Malani activity.
Similarly, the absence of any thrust zone, tectonic mélange and tectonised contact of the Malanis with the basement goes against
a plate subduction setting for their genesis. After the closure of orogenic cycles in the Aravalli craton of the northwestern
shield, this anorogenic intraplate magmatic activity took place in a cratonic rift setting under an extensional tectonic regime. 相似文献
925.
926.
—The maximum likelihood estimation of earthquake hazard parameters has been made in the Himalayas and its surrounding areas on the basis of a procedure which utilizes data containing complete files of the most recent earthquakes. The entire earthquake catalogue used covers the period from 1900–1990. The maximum regional magnitude M max?, the activity rate of the seismic event λ, the mean return period R of earthquakes with a certain lower magnitude M max≥ m along with their probability of occurrence, as well as the parameter b of of Gutenberg Richter magnitude-frequency relationship, have been determined for six different seismic zones of the Himalayas and its vicinity. It is shown that in general the hazard is higher in the zone NEI and BAN than the other four zones. The high difference of the b parameter and the hazard level from zone to zone reflect the high seismotectonic complexity and crustal heterogeneity. 相似文献
927.
T. N. Krishnamurti M. C. Sinha Vasubandhu Misra O. P. Sharma 《Dynamics of Atmospheres and Oceans》1998,27(1-4)
Over the upper troposphere of the polar latitudes the zonal flows exhibit a large variance on the time scale of the Madden-Julian oscillation, i.e. roughly 30–50 days. The other prominent regions for these intraseasonal oscillations are the Asian and Australian monsoon belts. These two regions are separated by the so-called critical latitude, to the south of which easterlies generally prevail and westerlies are prevalent to the north. A perplexing issue is that of possible tropical-middle latitude interactions across the critical latitude. The notion of the critical latitude emerged from the linear theories for the wave energy flux which assume a constancy in time for the zonal flows. This same problem, viewed in its full non-linear context, can be cast in a frequency domain. Such a formulation does not assume a constancy of the zonal flows in time but does permit the intraseasonal variations of the zonal flows to be present. The computation of the wave energy flux, from the more complete non-linear system in the frequency domain, requires the handling of linear, quadratic and triple product terms via use of Hayashi's co-spectral method. These results of the present study, based on 6 years of daily global data sets, show that wave energy flux clearly passes from the latitudes of the monsoon to the polar latitudes. A strong convergence of wave energy flux in the polar latitudes suggests the tropical-middle latitude convergence interactions across the so-called critical latitude—when the problem is viewed in the frequency domain. 相似文献
928.
Runoff (log-transformed) and sediment yield (log-transformed) sequences on a monthly or daily basis can be regarded as input and output for the watershed fluvial system. These sequences are nonstationary in general in different hydrological environments. Frequency and time domain analyses have shown that a parsimonious model can be built directly in terms of these nonstationary input-output sequences on a monthly and daily basis. A first-order dynamic model was found adequate to model the monthly runoff-sediment yield process; a second-order model adequately modeled the daily runoff-sediment yield process. The noise component in both cases possessed the characteristics of a white-noise sequence. 相似文献
929.
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
930.
Y. P. Sharma N. Lal K. D. Bal R. Parshad K. K. Nagpaul 《Contributions to Mineralogy and Petrology》1980,72(3):335-336
The fission track closing temperatures of the minerals which are found to be suitable for fission track geochronology have been calculated for various cooling rates using the stepwise cooling. Biotite is found to have the lowest closing temperature whereas the sphene is having the highest. The closing temperature falls with decrease in cooling rate. 相似文献