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281.
Summary Some direct methods of interpretation of SP anomalies that may arise from localised causative bodies have been developed in this paper. The models of the current sources that have been considered here are the cases of 1. single vertical dipole, 2. a pair of similar and similarly situated vertical dipoles and 3. an inclined dipole. A set of three master curves has been prepared in terms of which the interpretation in the first and the third case is complete. With an additional assumption that the distance between the dipoles is small, the second case also is completely solved with the help of the same set of master curves.Published under the kind permission of the Director General, Geological Survey of India, Calcutta. 相似文献
282.
Somnath Dasgupta H. Banerjee M. Fukuoka 《Contributions to Mineralogy and Petrology》1985,90(2-3):258-261
This paper aims to ascertain the degree of equilibrium attained with respect to oxygen during metamorphism of non-carbonatic
manganiferous sediments and the nature of mobility of oxygen in rocks of adjacent beds by measuring the composition of coexisting
phases. Through algebraic analysis of the relevant phase equilibria, a difference of ≃17 kcal in
in rocks of adjacent beds is obtained. This confirms the immobile nature of oxygen during metamorphism of manganiferous sediments. 相似文献
283.
284.
B. Banerjee S. M. Chitre P. P. Divakaran K. S. V. Santhanam 《Astrophysics and Space Science》1977,48(2):445-451
The possibility of chemical ‘trapping’ of the Ar+ ion in the reaction $$v{\text{ }} + {\text{ }}^{{\text{37}}} {\text{Cl}} \to {\text{ }}^{{\text{37}}} {\text{Ar}}^{\text{ + }} + {\text{ e}}^ - ,$$ when it takes place in tetrachloroethylene (C2Cl4) liquid, is examined in detail. It is concluded that if trapping does take place, the rate is much smaller than the charge neutralization rate. Therefore, this niechanism cannot explain the observed small rate of Ar production in the Brookhaven solar neutrino experiment. A detailed examination of a number of experiments which are sensitive to possible trapping lends strong support to this conclusion. 相似文献
285.
Pramod Kumar Pratul Kumar Saraswati Santanu Banerjee 《Journal of the Geological Society of India》2009,74(4):432-444
The Early Miocene succession of Kutch represents a mixed carbonate-siliciclastic depositional system. The carbonate part of
the succession, characterized by high abundance of shallow marine benthic fauna, hosts typical shell concentrations (also
referred as shell beds). The thickness of shell concentrations vary in scale from 5 cm to 100 cm and are separated by poorly
fossiliferous to barren silty shales/siltstones. Based on taphonomic and sedimentological observations, shell concentrations
are classified as lag, event, composite/multi-event and hiatal types. The occurrence of different types of shell concentrations
in the background of sequence stratigraphic framework is the main theme for the present study. Overall, the shell concentrations
occupy the middle part of the sequence i.e. upper part of the transgressive systems tract and lower part of the highstand
systems tract. Lag concentrations are found in the lower part of the sequence while composite concentrations, the major contributors
in the sequence, occur in upper part of the transgressive systems tract and in the lower part of the highstand systems tract.
The hiatal concentrations are associated with maximum flooding surface while the position of event concentrations is independent
of sequence stratigraphic framework. The shell concentrations occupy marine flooding surface or marine ravinement surface,
thus mark parasequence boundaries. 相似文献
286.
Saurabh Baruah Santanu Baruah Naba Kumar Gogoi Olga Erteleva Felix Aptikaev J. R. Kayal 《地震学报(英文版)》2009,(3):283-291
Strong ground motion parameters for Shillong plateau of northeastern India are examined. Empirical relations are obtained for main parameters of ground motions as a function of earthquake magnitude, fault type, source depth, velocity characterization of medium and distance. Correlation between ground motion parameters and characteristics of seismogenic zones are established. A new attenuation relation for peak ground acceleration is developed, which predicts higher expected PGA in the region. Parameters of ... 相似文献
287.
Shibaji Banerjee Sanjay K. Ghosh Amal Mazumdar Sibaji Raha Debapriyo Syam 《Astrophysics and Space Science》2000,274(3):655-660
There have been several reports of exotic nuclear fragments, with highly unusual charge to mass ratio, in cosmic ray experiments.
Although there exist experimental uncertainties which make them, at best, only candidate `exotic' events, it is important
to understand what they could be, if they are eventually confirmed. Among other possible explanations, some authors have interpreted
them to be lumps of strange quark matter (strangelets).A major problem with such an interpretation is that to reach the earth's
surface, they must possess an unusually high penetrability through the terrestrial atmosphere. We show that a recently proposed
mechanism for the propagation of strangelets through the earth's atmosphere, together with a proper account of charge capture
and ionisation loss, would solve this problem. We also argue that this could lead to viable strategies for definitive detection
of strange quark matter in cosmic ray flux using aground based large area array of passive detectors.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
288.
D. Banerjee 《Quaternary Geochronology》2010,5(2-3):279-282
The results of experiments which characterise the optically stimulated luminescence (OSL) signals of an ash sample (BI07-TL-05) from Barren Island are presented. The infrared stimulated luminescence signal decreases to 5% of its initial value when preheated at 150 °C for 10 s, suggesting that the infrared stimulated luminescence signal associated with the 290–390 nm emission in this sample arises from a single trap evicted by heating to 150 °C. The post-IR blue stimulated luminescence emission has greater thermal stability and arises from traps which are emptied by heating to temperatures between 120 °C and 240 °C. Dose recovery experiments demonstrate that a laboratory dose can be reliably determined to within 5% for the post-IR blue stimulated luminescence signal. However, the fading rate for the post-IR blue stimulation is high, and the g-value is estimated to be (9.6 ± 3.5)% per logarithmic decade for BI07-TL-05. 相似文献
289.
Different extractants were used to determine various forms of Fe and Al in three soil profiles developed under a tropical environment in India. The average contents of Fe and Al, extracted by different extracting reagents were found to be in descending order, as follows:
Analysis of pyrophosphate (pyr), oxalate (oxa) and dithionate (dith) extractable Fe and Al showed that with increasing soil age, the crystalline Fe and Al oxides increased at the expense of the poorly crystalline forms. The mean content of amorphous Fe and Al, crystalline Fe and Al and their ratio values in the three different soil series estimated the degree of soil development and were found to be in the following descending order: Ghoradanga >Kanchanpur >Lachimpur. Correlation between different forms of Fe and Al and selected soil properties were examined. Multiple regression equations were formulated to show the relation among soil properties and different forms of Fe and Al. 相似文献
290.
We examine spectral time series of the transition region line Ov 629Å, observed with the Coronal Diagnostic Spectrometer (CDS) on the SOHO spacecraft in July 1997. Both Fourier and wavelet transforms have been applied independently to the analysis of plume oscillations in order to find the most reliable periods. The wavelet analysis allows us to derive the duration as well as the periods of the oscillations. Our observations indicate the presence of compressional waves with periods of 10–25 min. We have also detected a 11±1 min periodicity in the network regions of the north polar coronal hole. The waves are produced in short bursts with coherence times of about 30 min. We interpret these oscillations as outward propagating slow magneto-acoustic waves, which may contribute significantly to the heating of the lower corona by compressive dissipation and which may also provide enough energy flux for the acceleration of the fast solar wind. The data support the idea that the same driver is responsible for the network and plume oscillations with the network providing the magnetic channel through which the waves propagate upwards from the lower atmosphere to the plumes. 相似文献