收费全文 | 347篇 |
免费 | 8篇 |
测绘学 | 31篇 |
大气科学 | 14篇 |
地球物理 | 55篇 |
地质学 | 177篇 |
海洋学 | 9篇 |
天文学 | 57篇 |
自然地理 | 12篇 |
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 5篇 |
2018年 | 10篇 |
2017年 | 22篇 |
2016年 | 10篇 |
2015年 | 8篇 |
2014年 | 24篇 |
2013年 | 16篇 |
2012年 | 16篇 |
2011年 | 19篇 |
2010年 | 13篇 |
2009年 | 21篇 |
2008年 | 10篇 |
2007年 | 15篇 |
2006年 | 7篇 |
2005年 | 10篇 |
2004年 | 4篇 |
2003年 | 8篇 |
2002年 | 8篇 |
2001年 | 7篇 |
2000年 | 6篇 |
1999年 | 5篇 |
1997年 | 10篇 |
1996年 | 7篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1987年 | 2篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1972年 | 1篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1967年 | 1篇 |
1964年 | 1篇 |
1963年 | 3篇 |
1962年 | 1篇 |
Sediment reworking near the ice-grounding line, extremely cold climate, high-energy storm sedimentation and anomalous water chemistry hindered organic colonization during the early phases of Talchir sedimentation. Later, climatic amelioration ushered in a favourable ambience for the benthic community to colonize within or beyond the storm weather wave-base in the outer shoreface–shelf environment. Fluctuating storm energy dominantly controlled the availability and influence of other environmental stimuli in the environment, and thus, governed the distribution, abundance and association of the studied ichnites. However, impoverished ichnodiversity, sporadic distribution of the traces, overall smaller burrow dimensions, absence of body fossils, dominance of worms and annelids as trace-makers all indicate a stressed environmental condition, induced by cold climate and lowered marine salinity due to influx of glacier melt-out freshwater during climatic amelioration, in the Permo-Carboniferous ice-marginal sea. 相似文献
– |
white massive tuff with ill-defined bedding contacts (facies-A) and 相似文献
36.
The relation between alkaline magmatism and tectonism has been a contentious issue, particularly for the Precambrian continental
regions. Alkaline complexes at the southwestern margin of Eastern Ghats belt, India, have been interpreted as rift-valley
magmatism. However, those complexes occurring in granulite ensemble in the interior segments of the Eastern Ghats belt could
not possibly be related to the rift-system, assumed for the western margin of the Eastern Ghats belt. Koraput complex was
emplaced in a pull-apart structure, dominated by magmatic fabrics and geochemically similar to a fractionated alkaline complex,
compatible with an alkalibasalt series. Rairakhol complex, on the other hand, shows dominantly solid-state deformation fabrics
and geochemically similar to a fractionated calc-alkaline suite. Isotopic data for the Koraput complex indicate ca. 917 Ma
alkaline magmatism from a depleted mantle source and postcrystalline thermal overprint at ca. 745 Ma, also recorded from sheared
metapelitic country rocks. The calc-alkaline magmatism of the Rairakhol complex occurred around 938 Ma, from an enriched mantle
source, closely following Grenvillian granulite facies imprint in the charnockitic country rocks. 相似文献
37.
In this study, the Tropical Rainfall Measurement Mission based Microwave Imager estimates (2A12) have been used to compare and contrast the characteristics of cloud liquid water and ice over the Indian land region and the ocean surrounding it, during the premonsoon (May) and monsoon (June–September) seasons. Based on the spatial homogeneity of rainfall, we have selected five regions for our study (three over ocean, two over land). Comparison across three ocean regions suggests that the cloud liquid water (CLW) over the orographically influenced Arabian Sea (close to the Indian west coast) behaves differently from the CLW over a trapped ocean (Bay of Bengal) or an open ocean (equatorial Indian Ocean). Specifically, the Arabian Sea region shows higher liquid water for a lower range of rainfall, whereas the Bay of Bengal and the equatorial Indian Ocean show higher liquid water for a higher range of rainfall. Apart from geographic differences, we also documented seasonal differences by comparing CLW profiles between monsoon and premonsoon periods, as well as between early and peak phases of the monsoon. We find that the CLW during the lean periods of rainfall (May or June) is higher than during the peak and late monsoon season (July–September) for raining clouds. As active and break phases are important signatures of the monsoon progression, we also analysed the differences in CLW during various phases of the monsoon, namely, active, break, active-to-break and break-to-active transition phases. We find that the cloud liquid water content during the break-to-active transition phase is significantly higher than during the active-to-break transition phase over central India. We speculate that this could be attributed to higher amount of aerosol loading over this region during the break phase. We lend credence to this aerosol-CLW/rain association by comparing the central Indian CLW with that over southeast Asia (where the aerosol loading is significantly smaller) and find that in the latter region, there are no significant differences in CLW during the different phases of the monsoon. While our hypothesis needs to be further investigated with numerical models, the results presented in this study can potentially serve as a good benchmark in evaluating the performance of cloud resolving models over the Indian region. 相似文献
38.
39.
40.
Achyuta Ayan Misra Gourab Bhattacharya Soumyajit Mukherjee Narayan Bose 《International Journal of Earth Sciences》2014,103(6):1645-1680
This is the first detailed report and analyses of deformation from the W part of the Deccan large igneous province (DLIP), Maharashtra, India. This deformation, related to the India–Seychelles rifting during Late Cretaceous–Early Paleocene, was studied, and the paleostress tensors were deduced. Near N–S trending shear zones, lineaments, and faults were already reported without significant detail. An E–W extension was envisaged by the previous workers to explain the India–Seychelles rift at ~64 Ma. The direction of extension, however, does not match with their N–S brittle shear zones and also those faults (sub-vertical, ~NE–SW/~NW–SE, and few ~N–S) we report and emphasize in this work. Slickenside-bearing fault planes, brittle shear zones, and extension fractures in meso-scale enabled us to estimate the paleostress tensors (directions and relative magnitudes). The field study was complemented by remote sensing lineament analyses to map dykes and shear zones. Dykes emplaced along pre-existing ~N–S to ~NE–SW/~NW–SE shears/fractures. This information was used to derive regional paleostress trends. A ~NW–SE/NE–SW minimum compressive stress in the oldest Kalsubai Subgroup and a ~N–S direction for the younger Lonavala, Wai, and Salsette Subgroups were deciphered. Thus, a ~NW/NE to ~N–S extension is put forward that refutes the popular view of E–W India–Seychelles extension. Paleostress analyses indicate that this is an oblique rifted margin. Field criteria suggest only ~NE–SW and ~NW–SE, with some ~N–S strike-slip faults/brittle shear zones. We refer this deformation zone as the "Western Deccan Strike-slip Zone" (WDSZ). The observed deformation was matched with offshore tectonics deciphered mainly from faults interpreted on seismic profiles and from magnetic seafloor spreading anomalies. These geophysical findings too indicate oblique rifting in this part of the W Indian passive margin. We argue that the Seychelles microcontinent separated from India only after much of the DLIP erupted. Further studies of magma-rich passive margins with respect to timing and architecture of deformation and emplacement of volcanics are required. 相似文献
|