全文获取类型
收费全文 | 331篇 |
免费 | 4篇 |
国内免费 | 10篇 |
专业分类
测绘学 | 26篇 |
大气科学 | 11篇 |
地球物理 | 66篇 |
地质学 | 146篇 |
海洋学 | 24篇 |
天文学 | 53篇 |
综合类 | 11篇 |
自然地理 | 8篇 |
出版年
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 7篇 |
2018年 | 13篇 |
2017年 | 25篇 |
2016年 | 9篇 |
2015年 | 9篇 |
2014年 | 25篇 |
2013年 | 23篇 |
2012年 | 13篇 |
2011年 | 17篇 |
2010年 | 13篇 |
2009年 | 20篇 |
2008年 | 15篇 |
2007年 | 9篇 |
2006年 | 9篇 |
2005年 | 4篇 |
2004年 | 3篇 |
2003年 | 7篇 |
2002年 | 5篇 |
2001年 | 4篇 |
2000年 | 7篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1996年 | 2篇 |
1994年 | 2篇 |
1992年 | 2篇 |
1991年 | 6篇 |
1989年 | 6篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1970年 | 3篇 |
1969年 | 2篇 |
1968年 | 4篇 |
1965年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有345条查询结果,搜索用时 15 毫秒
41.
Aeromagnetic anomalies over Bastar craton and Pranhita-Godavari (P-G) basin in the south of central India could be attributed
to NW-SE striking mafic intrusives in both the areas at variable depths. Such intrusions can be explained considering the
collision of the Bastar and Dharwar cratons by the end of the Archaean and the development of tensile regimes that followed
in the Paleoproterozoic, facilitating intrusions of mafic dykes into the continental crust. The P-G basin area, being a zone
of crustal weakness along the contact of the Bastar and Dharwar cratons, also experienced extensional tectonics. The inferred
remanent magnetization of these dykes dips upwards and it is such that the dykes are oriented towards the east of the magnetic
north at the time of their formation compared to their present NW-SE strike. Assuming that there was no imprint of magnetization
of a later date, it is concluded that the Indian plate was located in the southern hemisphere, either independently or as
part of a supercontinent, for some span of time during Paleoproterozoic and was involved in complex path of movement and rotation
subsequently. The paper presents a case study of the utility of aeromagnetic anomalies in qualitatively deducing the palaeopositions
of the landmasses from the interpreted remanent magnetism of buried intrusive bodies. 相似文献
42.
Time-dependent magneto-hydrodynamic simulations of active region coronal magnetic field require the underlying photospheric magnetic footpoint velocities. The minimum energy fit (MEF) is a new velocity inversion technique to infer the photospheric magnetic footpoint velocities using a pair of vector magnetograms, introduced by Longcope (2004). The MEF selects the smallest overall flow from several consistent flows by minimizing an energy functional. The inferred horizontal and vertical flow fields by the MEF can be further constrained by incorporating the partial or imperfect velocity information obtained through independent means. This hybrid method is expected to give a velocity close to the true magnetic footpoint velocity. Here, we demonstrate that a combination of the MEF, the local correlation tracking (LCT) and Doppler velocity is capable of inferring the velocity close to the photospheric flow. 相似文献
43.
N.G.Rudraswami A.K.Naik R.P.Tripathi N.BhANDari S.G.Karapurkar M.Shyam Prasad E.V.S.S.K.Babu U.V.R.Vijaya Sarathi 《地学前缘(英文版)》2019,10(2):495-504
The carbonaceous chondrites are intriguing and unique in the sense that they are the only rocks that provide pristine records of the early solar nebular processes. We report here results of a detailed mineralogical, chemical, amino acid and isotopic studies of a recently observed fall at Mukundpura, near Jaipur in Rajasthan, India. Abundance of olivines in this meteorite is low and of serpentine minerals is high. FeO/SiO_2 = 1.05 in its Poorly Characterized Phases(PCP) is similar to that observed in other CM2.0 chondrites. The water content of ~9.8 wt.% is similar to that found in many other CM chondrites.Microscopic examination of matrix shows that its terrestrial weathering grade is WO but aqueous parent body alteration is high, as reflected in low abundance of identifiable chondrules and abundant remnants of chondrules(~7%). Thus, most of the chondrules formed initially have been significantly altered or dissolved by aqueous alterations on their parent bodies. The measured bulk carbon(2.3%) and nitrogen content and their isotopic(δ13C =-5.5‰, δ15N = 23.6%0) composition is consistent with CM2.0 classification probably bordering CM1. Several amino acids such as Alanine, Serine, Proline, Valine, Threonine,Leucine, Isoleucine, Asparagine and Histamine are present. Tyrosine and Tryptophan may occur in trace amounts which could not be precisely determined. All these data show that Mukundpura chondrite lies at the boundary of CM2.0 and CM1 type carbonaceous chondrites making it one of the most primitive chondrites. 相似文献
44.
K. Babu Govindha Raj 《Journal of the Indian Society of Remote Sensing》2017,45(6):1031-1038
The importance of mass wasting in glacier environments and its impacts on glacier dynamics is not fully understood. This is the first occurrence of a debris avalanche event onto a Himalayan glacier through satellite data analysis. The analysis of various factors indicates the slide was a climate-driven hill-slope event activated in 2009 masking the Miyar glacier surface up to ~1.5% including its both lateral moraines and medial moraines. Due to this addition the glacier had neither advance nor retreat from 2009 to 2014. Eventually the debris will contribute to the supraglacial and englacial debris of the glacier. This showcases the way of mass wasting an important contribution to the debris budget of the Himalayan glaciers. 相似文献
45.
Lalmani Babu Madhu Kaul Kumar Rajou Singh Rajesh Singh Krishna Kumar 《Earth, Moon, and Planets》1999,84(3):151-162
The propagationmechanism of low latitude daytime whistlers is investigated on the basis of ground measurements made continuously
during daytime in North India at Jammu (geomag. lat. 22°26°N;L = 1.17). On February 14, 1998 extremely small dispersion (ESD)
whistlers with dispersion varying from 5–10 sec1/2 in surprisingly large numbers were recorded at Jammu during daytime in the late afternoon. The results of a study of the
characteristics of ESD whistlers are presented and the discussion indicates that ESD whistlers recorded are the VLF waves
radiated from the return stroke of the lightning discharge launched at the ionosphere with different initial wave normal angles,
propagated upwards under eitherquasi-longitudinal conditions or pro-longitudinal whistler mode, turned around at different
heights due to quasi-transverse propagation and received at Jammu with the dispersion of the order of 5–10 sec1/2. The validity of this suggestion has been tested by performing actualray-tracing computations in thepresence of equatorial
anomaly model.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
46.
Tapas R. Martha Priyom Roy Ritwik Mazumdar K. Babu Govindharaj K. Vinod Kumar 《Landslides》2017,14(2):697-704
High magnitude earthquakes trigger numerous landslides and their occurrences are mainly controlled by terrain parameters. We created an inventory of 15,551 landslides with a total area of 90.2 km2 triggered by the 2015 Mw 7.8 (Gorkha) and Mw 7.3 (Dolakha) earthquakes in Nepal, through interpretation of very high resolution satellite images (e.g. WorldView, Pleiades, Cartosat-1 and 2, Resourcesat-2). Our spatial analysis of landslide occurrences with ground acceleration, slope, lithology and surface defomation indicated ubiquitous control of steep slope on landslides with ground acceleration as the trigger. Spatial distribution of landslides shows increasing frequency away from the Gorkha earthquake epicentre up to 130 km towards east, dropping sharply thereafter, which is an abnormal phenomenon of coseismic landslides. Landslides are laterally concentrated in three zones which matches well with the seismic rupture evolution of Gorkha earthquake, as reported through teleseismic measurements. 相似文献
47.
A three-dimensional numerical model is developed and used to study the coastal upwelling processes and corresponding seasonal changes in the sea level along the west coast of India. The upwelling and associated sea level variations are seen as a response of coastal ocean to pure wind stress forcing. The model is designed to represent coastal ocean physics by resolving surface and bottom Ekman layers as realistically as possible. The prognostic variables are the three components of the velocity field, temperature, salinity and turbulent energy. The governing equations together with their boundary conditions are solved by finite-difference techniques. Experiments are performed to investigate sea level fluctuations associated with the thermal response and alongshore currents of the coastal waters. The model is forced with mean monthly wind stress forcing of January, May, July and September representing northeast monsoon and different phases of the southwest monsoon. It is known from the observational study that the upwelling process reaches to the surface waters by May along the coastal waters of the extreme southwest peninsular region. The process is more intense in July compared to May and September and its strength decreases from south to north. However, during the northeast monsoon season, which is represented by January wind stress forcing in the model, downwelling is simulated along the coast. The model simulations of the coastal response are compared with the observations and are found to be in good agreement. The maximum computed vertical velocity of about 2.0 2 10 -3 cm s -1 is predicted in July in the southern region off the coast. 相似文献
48.
Bohuslav R??ek Jaroslava Plomerová Vladislav Babu?ka 《Studia Geophysica et Geodaetica》2012,56(1):107-140
Joint inversion of teleseismic P-waveforms and local group velocities of surface waves retrieved from ambient seismic noise
has been performed to model velocity structure of the crust and uppermost mantle of the Bohemian Massif. We analysed P-waveforms
of 381 teleseismic earthquakes recorded at 54 broadband seismic stations located on the territory of the Czech Republic and
in its close surroundings. Group velocities of Rayleigh and Love surface waves were obtained by cross-correlating long-term
recordings of seismic noise. The basis for waveform inversion is the well-known methodology of P-to-S receiver functions constructed
from converted phases. Due to instabilities in direct inversion of receiver functions caused by the necessity of applying
deconvolution, we propose an alternative formulation to fit observed and calculated radial components of P waveforms. The
joint inversion is transformed into a search for the minimum of the cost function defined as a weighted sum of waveform and
group velocity misfits. With the use of the robust stochastic optimizer (Differential Evolution Algorithm), neither derivatives
nor a starting model are needed. The task was solved for 1D layered isotropic models of the crust and the uppermost mantle.
We have performed a sequence of inversions with models containing one, two, three and four layers above a half-space. By using
statistical criteria (F-test) we were able to select the simplest velocity models satisfying data and representing local geological
structures. Complex crustal models are typical for stations located close to boundaries of major tectonic units. The relatively
low average P to S wave-velocity ratio is in agreement with the generally accepted view that the BM crust is predominantly
felsic. 相似文献
49.
Lavkush Kumar Patel Parmanand Sharma C. M. Laluraj Meloth Thamban Ajit Singh Rasik Ravindra 《Natural Hazards》2017,86(3):1275-1290
Geospatial studies carried out in two major proglacial lakes of Samudra Tapu and Gepang Gath (Chandra Basin, Western Himalaya) showed substantial expansion in their area and volume over the last four decades (1971–2014). The linear and areal expansions for the lakes Samudra Tapu and Gepang Gath were 1889, 1509 m and 1, 0.6 km2, respectively. The results show that increased melting of the feeder glaciers over this period is major contributor to expand the volumes approximately 20 times of both the lakes Samudra Tapu and Gepang Gath. This expansion of lakes volume of Samudra Tapu and Gepang Gath from 3.4 × 106 to 67.7 × 106 and 1.5 × 106 to 27.5 × 106 m3, respectively, is quite significance in terms of hazards generated from glacial lake outburst floods (GLOF). This kind of climate change induced increase in the rate of glacial melting is a cause of concern, as the Himalaya Mountains may turn out to be vulnerable to natural hazards like GLOF. 相似文献
50.
S. Suresh Babu V. Sreekanth Vijayakumar S Nair S.K. Satheesh K. Krishna Moorthy 《Journal of Atmospheric and Solar》2010,72(11-12):876-882
Altitude profile of aerosol Single Scattering Albedo (SSA), derived from simultaneous in-situ airborne measurements of the coefficients of aerosol absorption and scattering off the west coast of India over the Arabian Sea (AS), during January 2009 is presented. While both the absorption and scattering coefficients decreased with altitude, their vertical structure differed significantly. Consequently, the derived SSA, with a surface value of 0.94, decreased with altitude, illustrating increasing relative dominance of aerosol absorption at higher altitudes. Altitude profile of SSA, when examined in conjunction with that of hemispheric backscatter fraction, revealed that the continental influence on the aerosol properties was higher at higher altitude, rather than the effect of marine environment. During an east–west transect across the peninsular India at an altitude of ~2500 m (free troposphere), it was found that the aerosol scattering coefficients remained nearly the same over both east and west coasts. 相似文献