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111.
K. S. N. Reddy D. Deva Varma E. N. Dhanamjaya Rao B. Veeranarayana T. Lakshmi Prasad 《Journal of the Geological Society of India》2012,79(4):411-418
Heavy mineral analysis was carried out for the beach and fore dune sediments along 60 transects of Nizampatnam-Lankavanidibba
coastal area. The heavy mineral assemblage in this area with decreasing abundance of opaques (Ilmenite + magnetite, 47.67%),
pyriboles (20.35%), garnets (3.66%), epidote (3.23%) and with less than 3.0% concentration of sillimanite, zircon, staurolite,
kyanite, apatite, spinel, monazite, biotite, topaz, leucoxene and chlorite. The heavy mineral concentrations are high in the
finer fractions i.e., +120 and +230 (ASTM) than the coarse fraction (+60) of sand. In the seven sectors, heavy mineral assemblage
is same but their concentrations are different. The sectors nearer to the river mouth contain high concentration of high specific
gravity heavy minerals (ilmenite and magnetite) than sectors away from the river mouth. The redistribution of heavy minerals
is controlled by creek dynamics, longshore currents, size and specific gravity of the heavy minerals. 相似文献
112.
113.
T. Seshunarayana B. Rajendra Prasad A. S. S. S. R. S. Prasad D. Mysaiah 《Journal of the Geological Society of India》2011,77(3):213-218
A detailed, integrated gravity and magnetic study across the Main Central Thrust (MCT) along the Pala-Maneri traverse in Uttaranchal,
NW Himalaya was carried out. The gravity data was acquired using a CG-3 gravity meter with an accuracy of 0.005 mGal, while
magnetic data was acquired using a proton precession magnetometer with a station interval of 20 m. Data was collected along
a 11.7 km, NE-SW traverse from Pala to Maneri along the proposed route of a hydroelectric headrace tunnel. The measured variation
in the gravity field was approximately 70 mGal, with two prominent highs recorded at distances of 0.5 km, 7.5 km and lows
at 3.0 km, 10.5 km from Maneri. The gravity highs can be attributed to presence of high-density rocks along the thrust planes.
The sharp gravity low recorded at 10.5 km distance possibly indicates a sympathetic fault of the MCT that is highly saturated
with fluids (water). The broad gravity low between 2.5 km and 4.0 km distance is likely to represent the gravity signature
of the MCT itself. The measured variation in the magnetic field was approximately 285 nT. The associated gravity and magnetic
signatures located several faults along the traverse including presence of the MCT at Kumaltigad. 相似文献
114.
Frédéric Girault Ananta Prasad Gajurel Frédéric Perrier Bishal Nath Upreti Patrick Richon 《Journal of Asian Earth Sciences》2011,40(2):595-610
Effective radium-226 concentration (ECRa) has been measured in soil samples from seven horizontal and vertical profiles of terrace scarps in the northern part of Kathmandu Valley, Nepal. The samples belong to the Thimi, Gokarna, and Tokha Formations, dated from 50 to 14 ky BP, and represent a diverse fluvio-deltaic sedimentary facies mainly consisting of gravelly to coarse sands, black, orange and brown clays. ECRa was measured in the laboratory by radon-222 emanation. The samples (n = 177) are placed in air-tight glass containers, from which, after an accumulation time varying from 3 to 18 days, the concentration of radon-222, radioactive decay product of radium-226 and radioactive gas with a half-life of 3.8 days, is measured using scintillation flasks. The ECRa values from the seven different profiles of the terrace deposits vary from 0.4 to 43 Bq kg?1, with profile averages ranging from 12 ± 1 to 27 ± 2 Bq kg?1. The values have a remarkable consistency along a particular horizon of sediment layers, clearly demonstrating that these values can be used for long distance correlations of the sediment horizons. Widely separated sediment profiles, representing similar stratigraphic positions, exhibit consistent ECRa values in corresponding stratigraphic sediment layers. ECRa measurements therefore appear particularly useful for lithologic and stratigraphic discriminations. For comparison, ECRa values of soils from different localities having various sources of origin were also obtained: 9.2 ± 0.4 Bq kg?1 in soils of Syabru–Bensi (Central Nepal), 23 ± 1 Bq kg?1 in red residual soils of the Bhattar-Trisuli Bazar terrace (North of Kathmandu), 17.1 ± 0.3 Bq kg?1 in red residual soils of terrace of Kalikasthan (North of Trisuli Bazar) and 10 ± 1 Bq kg?1 in red residual soils of a site near Nagarkot (East of Kathmandu). The knowledge of ECRa values for these various soils is important for modelling radon exhalation at the ground surface, in particular in the vicinity of active faults. Importantly, the study also reveals that, above numerous sediments of Kathmandu Valley, radon concentration in dwellings can potentially exceed the level of 300 Bq m?3 for residential areas; a fact that should be seriously taken into account by the governmental and non-governmental agencies as well as building authorities. 相似文献
115.
116.
B. Venkateswara Rao Y. Siva Prasad K. Srinivas Reddy 《Journal of the Geological Society of India》2013,81(4):521-530
Investigation for high yielding water wells in the khondalitic terrain (graneti ferrous silliminite gnesiss) is mostly faced with the problem of identification of the extent of the depth of kaolinisation of the aquifer. The traditional Vertical Electrical Sounding survey, Seismic Refraction survey and Very Low Frequency Electromagnetic survey could not identify the kaolinisation of the aquifer in the present investigations. The Two Dimensional (2D) Resistivity and Induced Polarization (IP) Imaging surveys are attempted for the identification of kaolinised layer and depth of kaolinisation. Number of 2D Resistivity and IP Imaging profiles were conducted near Chipurupally in Vizianagaram district of Andhra Pradesh, India along successful and failed wells located within short distances. Resistivity and IP measurements were carried out using an ABEM SAS 4000 Terrameter. The resistivity and I.P. images have provided a clear view of the thickness of the highly weathered zone (kaolinised zone) at both successful and failed wells. The highly weathered zone is identified with the resistivity values below 25 ohm.m. The depth of highly weathered material at failed well is extended about 8–10 m more deeper than the successful wells at some places to as much as 20 m more deep at some other places. This extended deeper kaolinisation of the aquifer is responsible for failure of wells. Layers having resistivities between 25–65 Ohm.m are identified as aquifer layers which are composed of moderately weathered and fractured khondalitic suit of rocks (Garnti ferrous sillimanite/biotite gneiss). Layers with resistivities greater than 65 Ohm.m are interpreted to have basement characteristics belonging to the granite gneiss. Interestingly IP imaging has not provided any greater insights in delineating the kaolinistion of the aquifer when compared to resistivity Imaging, in fact resitivity imaging has shown greater depths of kaolinisation than IP Imaging. 相似文献
117.
Semra komatiites that occur at the NW fringe of the Chotanagpur Gneissic Complex represent high PGE content, associated with the pyrrhotite, pentlandite, chalcopyrite and pyrite. They display wide variation in the IPGE concentration and characterized by Pd/Pt values (> 1) similar to that of primitive mantle. The negative Ir anomaly is attributed to temperature dependant solubility limit, therefore, not a reflection of bulk mantle IPGE content. Wide variation in the Au content indicates its highly mobile nature. Metasomatism and serpentinisation possibly have played significant role in the Au enrichment. 相似文献
118.
The aim of the present study is to understand the impact of oceanic heat potential in relation to the intensity of tropical cyclones (TC) in the Bay of Bengal during the pre-monsoon (April–May) and post-monsoon (October–November) cyclones for the period 2006–2010. To accomplish this, the two-layer gravity model (TLGM) is employed to estimate daily tropical cyclone heat potential (TCHP) utilizing satellite altimeter data, satellite sea surface temperature (SST), and a high-resolution comprehensive ocean atlas developed for Indian Ocean, subsequently validated with in situ ARGO profiles. Accumulated TCHP (ATCHP) is estimated from genesis to the maximum intensity of cyclone in terms of minimum central pressure along their track of all the cyclones for the study period using TLGM generated TCHP and six-hourly National Centre for Environmental Prediction Climate Forecast System Reanalysis data. Similarly, accumulated sea surface heat content (ASSHC) is estimated using satellite SST. In this study, the relationship between ATCHP and ASSHC with the central pressure (CP) which is a function of TC intensity is developed. Results reveal a distinct relationship between ATCHP and CP during both the seasons. Interestingly, it is seen that requirement of higher ATCHP during pre-monsoon cyclones is required to attain higher intensity compared to post-monsoon cyclones. It is mainly attributed to the presence of thick barrier layer (BL) resulting in higher enthalpy fluxes during post-monsoon period, where as such BL is non-existent during pre-monsoon period. 相似文献
119.
T. V. M. Sreekanth P. C. Nagajyothi K. D. Lee T. N. V. K. V. Prasad 《International Journal of Environmental Science and Technology》2013,10(5):1129-1140
The focus of the review is on the specific aspects of nickel’s effects on growth, morphology, photosynthesis, mineral nutrition and enzyme activity of plants. The mobility of nickel in the environment and the consequent contamination in soil and water is of great concern. Also, the detrimental effects of excessive nickel on plant growth have been well known for many years. Toxic effects of nickel on plants include alterations in the germination process as well as in the growth of roots, stems and leaves. Total dry matter production and yield was significantly affected by nickel and also causes deleterious effects on plant physiological processes, such as photosynthesis, water relations and mineral nutrition. Nickel strongly influences metabolic reactions in plants and has the ability to generate reactive oxygen species which may cause oxidative stress. More recent evidence indicates that nickel is required in small amounts for normal plant growth and development. Hence, with the increasing level of nickel pollution in the environment, it is essential to understand the functional roles and toxic effects of nickel in plants. 相似文献
120.
P. J. C. Favas J. Pratas M. N. V. Prasad 《International Journal of Environmental Science and Technology》2013,10(4):809-826
The uptake of arsenic and other metals (iron, manganese, copper, zinc, lead, nickel and tungsten) by Pinus pinaster Aiton (the maritime pine tree) growing in soils and tailings around an abandoned mine (northern Portugal) was investigated. Aerial parts of Pinus pinaster trees were sampled from three substrate areas: a background area, in mine contaminated soils and in tailings. Vegetation material was separated into needles and stems and subdivided into tissues of different maturities (1-, 2-, 3- and 4-years-old). The sampling of the substrate in each area was also undertaken. In general, vegetation concentrations were strongly related to substrate concentrations. The results show that the contents of several elements depend as much on the plant organ as on the age of the tissue. For the researched elements, this species shows a great variability in behavior depending on the age of the organ. The data indicate that the older needles constitute the best samples for use in a conjunct biogeochemical analysis of these elements. 相似文献