全文获取类型
收费全文 | 297篇 |
免费 | 11篇 |
国内免费 | 9篇 |
专业分类
测绘学 | 11篇 |
大气科学 | 5篇 |
地球物理 | 83篇 |
地质学 | 163篇 |
海洋学 | 13篇 |
天文学 | 17篇 |
综合类 | 2篇 |
自然地理 | 23篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 9篇 |
2020年 | 3篇 |
2019年 | 8篇 |
2018年 | 19篇 |
2017年 | 18篇 |
2016年 | 29篇 |
2015年 | 12篇 |
2014年 | 28篇 |
2013年 | 22篇 |
2012年 | 18篇 |
2011年 | 20篇 |
2010年 | 14篇 |
2009年 | 11篇 |
2008年 | 22篇 |
2007年 | 8篇 |
2006年 | 15篇 |
2005年 | 6篇 |
2004年 | 5篇 |
2003年 | 9篇 |
2002年 | 8篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1977年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有317条查询结果,搜索用时 15 毫秒
311.
Static spherically-symmetric solutions to the linearized field equations of a generalized scalartensor theory of gravity are derived. The gravitational potential outside such a source is determined; it is found that this potential can have an intermediate range variation. The question of whether such an intermediate range variation would manifest itself in two experiments is addressed. 相似文献
312.
Mustafa önal 《Earth, Moon, and Planets》1988,43(2):117-121
It was verified that the total number of sunspot groups at certain region on the solar surface for a certain activity cycle can be estimated quite accurately by using the Markov chain approximation method on the total number of spot groups observed on the same region at an earlier activity cycle. Application has been carried out on the observed sunspots on three northern longitude intervals (40–50, 80–90, and 130–140) during the activity cycle 1950–1960 and 1960–1970. The total number of spot groups in these regions for the activity cycle 1960–1970 has been estimated from the observational data of the cycle 1950–1960. A good correlation between the observed and estimated number of spot groups for the activity cycle 1960–1970 has been noted. 相似文献
313.
Mustafa önal 《Earth, Moon, and Planets》1988,43(2):107-115
The positions of the 13588 sunspot groups observed during the cycle of 1950–1960 at the Istanbul University Observatory have been corrected for the effect of differential rotation. The evolution probability of a sunspot group to the other one in the same region have been determined. By using the Markov chain approximation, the types of these groups and their transition probabilities during the following activity cycle (1950–1960), and the concentration of active regions during 1950–1960 have been estimated. The transition probabilities from the observations of activity cycle 1960–1970 have been compared with the predicted transition probabilities and a good correlation has been noted. 相似文献
314.
Engineering geological and geotechnical site characteristics were assessed and seismic hazard studies performed for the Upper
Pliocene to Pleistocene fluvial and Quaternary alluvial and terrace deposits for a site west of Ankara, Turkey. Sediment conditions
were determined and a soil profile was characterized by surface geophysical methods. These studies were integrated with existing
in-situ characterization studies to create a seismic and geotechnical database for the site. A seismic zonation map of the
site was then prepared. Site classification systems were assigned to account for site effects in relation to seismic hazard
assessments. The consequences of the seismic hazards were investigated and recommendations were presented. 相似文献
315.
GIS-based sustainable city compactness assessment using integration of MCDM,Bayes theorem and RADAR technology 总被引:1,自引:0,他引:1
In recent decades, compact urban development and smart cities are recognised as most sustainable urban form in an effort to protect natural environment. Therefore, evaluation of existing compactness and sustainability of an area is an essential task before the real development takes place. In the literature, it is possible to see some studies on city’s compactness assessment and most of them have considered only a few aspects of compact development analysis. This paper aims to analyse urban sustainability of Kajang city (Malaysia) through a comprehensive city compactness assessment using geographical information system and radar remote sensing technology. To measure building density, a RADAR image of the study area was used to extract built-up areas with the aid of pixel-based and object-based classification schemes. Mixed land use development, urban density and intensity were the main indicators of the analysis. Finally, multicriteria decision-making and Bayes theorems were applied for overall compactness assessment. Building density analysis was validated using standard confusion matrix, which showed more than 90% accuracy. Similarly, the root-mean squared error showed 0.35 for object-based classification. The results classified the zones of the Kajang city in the range of least to most compact zones with the compactness value of 0.00273–0.0146, respectively. The results obtained in this study can help local government to improve the compactness of least compact zones to make Kajang city more sustainable. Furthermore, the results revealed that efficient public transportation and proper community facilities are the key factors to achieve sustainable urban development. 相似文献
316.
M. Julleh Jalalur Rahman Peter Faupl M. Mustafa Alam 《International Journal of Earth Sciences》2009,98(8):1971-1980
The Bengal Basin, in the north-eastern part of the Indian subcontinent, contains a thick (± 22 km) early Cretaceous-Holocene
sedimentary succession. The Neogene succession in the Sylhet Trough of the basin reaches a thickness of more than 6 km of
which the Surma Group contains important sandstone reservoirs. Lithologically, the group consists of a succession of alternating
shales, siltstones, sandy shales and sandstones, with minor conglomerates. This research work is a sedimentological analysis
of the subsurface Neogene succession encountered in the petroleum exploration wells in the Sylhet Trough of the Bengal Basin.
Detailed lithologic logs of the cores, based on considering texture and sedimentary structure, permit a subdivision into eight
lithofacies, e.g., a shale-dominated facies, interbedded fine sandstones and mudstones, ripple-laminated sandstones, parallel-laminated
sandstones, massive sandstones, cross-bedded sandstones, cross-bedded sandstones with pebble/granule lag and conglomerates.
Characteristic sedimentary structures of the Surma Group, such as flaser-, wavy- and lenticular-bedding, bipolarity of ripple
cross-stratification, evenly laminated sand/silt-streaked shales, reactivation surfaces within cross-bedded sandstone sets,
mud-drapes on foreset laminae and herringbone cross-stratification as well as small-scale vertical sequences (several fining-upward
cycles) are diagnostic for tidal influence. On the basis of the lithofacies associations and prograding character of the deposits
revealed from the electrofacies associations, the Surma Group sediments have been interpreted as representing deposits of
tide-dominated deltaic depositional setting. 相似文献
317.
Insights into biaxial extensional tectonics: an examplefrom the Sandıklı Graben,West Anatolia,Turkey
West Anatolia, together with the Aegean Sea and the easternmost part of Europe, is one of the best examples of continental extensional tectonics. It is a complex area bounded by the Aegean–Cyprus Arc to the south and the North Anatolian Fault Zone (NAFZ) to the north. Within this complex and enigmatic framework, the Sandıklı Graben (10 km wide, 30 km long) has formed at the eastern continuation of the Western Anatolian extensional province at the north‐northwestward edge of the Isparta Angle. Recent studies have suggested that the horst–graben structures in West Anatolia formed in two distinct extensional phases. According to this model the first phase of extension commenced in the Early–Middle Miocene and the last, which is accepted as the onset of neotectonic regime, in Early Pliocene. However, it is controversial whether two‐phase extension was separated by a short period of erosion or compression during Late Miocene–Early Pliocene. Both field observations and kinematic analysis imply that the Sandıklı Graben has existed since the Late Pliocene, with biaxial extension on its margins which does not necessarily indicate rotation of regional stress distribution in time. Although the graben formed later in the neotectonic period, the commencement of extension in the area could be Early Pliocene (c. 5 Ma) following a severe but short time of erosion at the end of Late Miocene. The onset of the extensional regime might be due to the initiation of westward motion of Anatolian Platelet along the NAFZ that could be triggered by the higher rate of subduction at the east Aegean–Cyprus Arc in the south of the Aegean Sea. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献