全文获取类型
收费全文 | 358篇 |
免费 | 19篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 5篇 |
大气科学 | 11篇 |
地球物理 | 129篇 |
地质学 | 188篇 |
海洋学 | 20篇 |
天文学 | 16篇 |
综合类 | 3篇 |
自然地理 | 6篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 10篇 |
2021年 | 7篇 |
2020年 | 6篇 |
2019年 | 5篇 |
2018年 | 29篇 |
2017年 | 21篇 |
2016年 | 39篇 |
2015年 | 18篇 |
2014年 | 39篇 |
2013年 | 34篇 |
2012年 | 29篇 |
2011年 | 33篇 |
2010年 | 29篇 |
2009年 | 24篇 |
2008年 | 10篇 |
2007年 | 7篇 |
2006年 | 9篇 |
2005年 | 1篇 |
2004年 | 5篇 |
2003年 | 5篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有378条查询结果,搜索用时 15 毫秒
81.
Özgür Gültekin Emine Rızaoǧlu K. Gediz Akdeniz 《Journal of Astrophysics and Astronomy》2013,34(4):349-355
The frequency intervals in which O VI ions get in resonance with ion–cyclotron waves are calculated using the kinetic model, for the latest six values found in literature on O VI ion number densities in the 1.5R–3R region of the NPCH. It is found that the common resonance interval is 1.5 kHz to 3 kHz. The R-variations of wave numbers necessary for the above calculations are evaluated numerically, solving the cubic dispersion relation with the dielectric response derived from the quasi-linear Vlasov equation for the left-circularly polarized ion-cyclotron waves. 相似文献
82.
Pelin Tohumcu Özener Kutay Özaydın Mehmet M. Berilgen 《Bulletin of Earthquake Engineering》2009,7(1):199-219
This paper presents the results of shaking table model tests which were carried out to investigate the pore water pressure
generation and related liquefaction mechanism in layered sand deposits. The experiments were performed on uniform sand columns,
silt interlayered sand columns and two layered sand columns deposited at various relative densities and subjected to different
input excitations. During the experiments excess pore water pressures were measured by pore pressure transducers installed
at three different depths and, surface settlements and thickness of water film developed under less permeable inclusions were
measured by a digital camera. The experimental results are discussed and compared to demonstrate the effects of relative density,
input acceleration and presence of a silt seam on the generation of excess pore water pressure in sand deposits subjected
to dynamic loading. The results showed that the presence of a less permeable silt interlayer within the sand deposit and existence
of a loose sand layer underlying dense sand deposits can have significant effect on the pore water pressure generation mechanism. 相似文献
83.
84.
85.
86.
87.
88.
Development of ground-shaking maps for the Sultanate of Oman 总被引:1,自引:1,他引:0
89.
Hasan Sözbilir Çağlar Özkaymak Bora Uzel Ökmen Sümer Semih Eski Çiğdem Tepe 《Geodinamica Acta》2016,28(4):254-272
The Havran-Bal?kesir Fault Zone (HBFZ) is one of the major active structures of the Southern Marmara Region, which has been shaped by the southern branch of North Anatolian fault since the Pliocene. HBFZ is a 10–12 km wide, 120 km long, right-lateral strike-slip fault zone that consists of two ENE-striking main faults, namely, the Havran-Balya and Bal?kesir faults. The 90-km-long Havran-Balya fault exhibits right-stepping en echelon geometry and is made up of (1) Havran, (2) Osmanlar, (3) Turplu and (4) Ovac?k fault segments. On the eastern part, the 70-km-long Bal?kesir fault is divided into two fault segments; (1) Gökçeyaz? and (2) Kepsut. We estimated the long-term slip rate between 3.59 and 3.78 mm/yr using river offset. The Kepsut, Gökçeyaz? and Ovac?k fault segments are capable of generating an earthquake with a moment magnitude of up to 7.2. Detailed palaeoseismological studies show that the HBFZ is responsible for some surface faulting earthquakes with an average recurrence interval of 1000–2000 years during the late Holocene. Considering the fact that there was no evidence of a surface-ruptured earthquake for 2000 years, it can be stated that there is a seismic gap on the Gökçeyaz? fault segment. 相似文献
90.
Emre Aydınçakır 《Geodinamica Acta》2016,28(4):379-411
Mineral chemistry, major and trace elements, 40Ar/39Ar age and Sr–Nd–Pb isotopic data are presented for the Late Cretaceous Hamsilos volcanic rocks in the Central Pontides, Turkey. The Hamsilos volcanic rocks mainly consist of basalt, andesite and associated pyroclastics (volcanic breccia, vitric tuff and crystal tuff). They display shoshonitic and high-K calc-alkaline affinities. The shoshonitic rocks contain plagioclase, clinopyroxene, alkali feldspar, phlogopite, analcime, sanidine, olivine, apatite and titanomagnetite, whereas the high-K calc-alkaline rocks contain plagioclase, clinopyroxene, orthopyroxene, magnetite / titanomagnetite in microgranular porphyritic, hyalo-microlitic porphyritic and glomeroporphyritic matrix. Mineral chemistry data reveal that the pressure condition of the clinopyroxene crystallisation for the shoshonitic rocks are between 1.4 and 6.3 kbar corresponds to 6–18-km depth and the high-K calc-alkaline rocks are between 5 and 12 km. 40Ar/39Ar age data changing between 72 ± .5 Ma and 79.0 ± .3 Ma (Campanian) were determined for the Late Cretaceous Hamsilos volcanic rocks, contemporaneous with the subduction of the Neo-Tethyan Ocean beneath the Pontides. The studied volcanic rocks were enriched in the large-ion lithophile and light rare earth element contents, with pronounced depletion in the contents of high-field-strength elements. Chondrite-normalised rare earth element patterns (LaN/LuN = 6–17) show low to medium enrichment, indicating similar sources of the rock suite. Initial 87Sr/86Sr values vary between .70615 and .70796, whereas initial 143Nd/144Nd values change between .51228 and .51249. Initial 206Pb/204Pb values vary between 18.001 and 18.349, 207Pb/204Pb values between 15.611 and 15.629 and 208Pb/204Pb values between 37.839 and 38.427. The main solidification processes involved in the evolution of the volcanic rocks consist of fractional crystallisation, with minor amounts of crustal contamination ± magma mixing. According to geochemical evidence, the shoshonitic melts in the Hamsilos volcanic rocks were possibly derived from the low degree of partial melting of a subcontinental lithospheric mantle (SCLM), while the high-K calc-alkaline melts were derived from relatively high degree of partial melting of SCLM that was enriched by fluids and/or sediments from a subduction of oceanic crust. 相似文献