全文获取类型
收费全文 | 324篇 |
免费 | 16篇 |
国内免费 | 8篇 |
专业分类
测绘学 | 15篇 |
大气科学 | 20篇 |
地球物理 | 71篇 |
地质学 | 159篇 |
海洋学 | 13篇 |
天文学 | 45篇 |
综合类 | 1篇 |
自然地理 | 24篇 |
出版年
2023年 | 1篇 |
2022年 | 10篇 |
2021年 | 17篇 |
2020年 | 13篇 |
2019年 | 15篇 |
2018年 | 26篇 |
2017年 | 42篇 |
2016年 | 39篇 |
2015年 | 16篇 |
2014年 | 28篇 |
2013年 | 26篇 |
2012年 | 22篇 |
2011年 | 22篇 |
2010年 | 11篇 |
2009年 | 14篇 |
2008年 | 3篇 |
2007年 | 3篇 |
2006年 | 2篇 |
2005年 | 3篇 |
2004年 | 2篇 |
2002年 | 1篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 4篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有348条查询结果,搜索用时 843 毫秒
241.
Luke Ootes Steve Goff Valerie A. Jackson Sarah A. Gleeson Robert A. Creaser Iain M. Samson Norman Evensen Louise Corriveau A. Hamid Mumin 《Mineralium Deposita》2010,45(6):549-566
The timing of Cu–Mo–U mineralisation at the Nori/RA prospect in the Paleoproterozoic Great Bear magmatic zone has been investigated
using Re–Os molybdenite and 40Ar–39Ar biotite geochronology. The Re–Os molybdenite ages presented are the first robust sulphide mineralisation ages derived from
the Great Bear magmatic zone. Cu–Mo–U mineralisation is hosted in early to syn-deformational hydrothermal veins consisting
of quartz and K-feldspar or more commonly tourmaline-biotite-quartz-K-feldspar, with associated wall-rock alteration assemblages
being predominantly biotite. Sulphide and oxide minerals consist of chalcopyrite, molybdenite and uraninite with lesser pyrite
and magnetite. Elevated light rare earth elements and tungsten concentrations associated with the Cu–Mo–U mineralisation have
also been reported at the prospect by previous workers. Molybdenite and uraninite occur intimately in dravitic tourmaline
growth zones and at grain margins, attesting to their syngenetic nature (with respect to hydrothermal veining). Two molybdenite
separates yield Re–Os model ages of 1,874.4 ± 8.7 (2σ) and 1,872.4 ± 8.8 Ma (2σ) with a weighted average model age of 1,873.4 ± 6.1 Ma (2σ). Laser step heating of biotite from the marginal alteration of the wall-rock adjacent to the veins yields a 40Ar–39Ar maximum cooling age of 1,875 ± 8 Ma (MSWD = 3.8; 2σ), indistinguishable from the Re–Os molybdenite model age and a previously dated ‘syn-tectonic’ aplitic dyke in the region.
Dravitic tourmaline hosts abundant primary liquid–vapour–solid-bearing fluid inclusions. Analytical results indicate liquid–vapour
homogenisation at >260°C constraining the minimum temperature of mineralisation. The solids, which are possibly trapped, did
not homogenise with the liquid–vapour by 400°C. Salinities in the inclusions are variable. Raman spectra identify that at
least some of the solids are calcite and anhydrite. Raman spectra also confirm the vapour phases contain some CO2; whereas clathrates or CH4 was not observed or detected. Quartz grains only host secondary fluid inclusions, which fluoresce under ultraviolet light,
indicating trapped hydrocarbons. We speculate that these resulted from Phanerozoic fluid circulation through the Proterozoic
basement. The collective interpretation of the age, hydrothermal character and associated metals, high temperature and variable
salinity suggests that the Nori/RA Cu–Mo–U mineralisation can be linked with the earliest stages of plutonism in the Great
Bear magmatic zone. From a regional perspective, the mineralisation may pre-date the extensive multi-element mineralisation
now recognised as part of the iron oxide copper–gold (IOCG) spectrum of deposits. As IOCG provinces generally contain a variety
of mineralisation styles, we interpret this as the earliest phase of the extensive mineralising system. 相似文献
242.
243.
Frédéric Masson Mohammad Anvari Yahya Djamour rea Walpersdorf Farokh Tavakoli Marc Daignières Hamid Nankali Sébastien Van Gorp 《Geophysical Journal International》2007,170(1):436-440
A network of 26 GPS sites was implemented in Iran and Northern Oman to measure displacements in this part of the Arabia–Eurasia collision zone. We present the GPS velocity field obtained from three surveys performed in 1999 September, 2001 October and 2005 September and the deduced strain tensor. This study refines previous studies inferred from only the two first surveys. Improvements are significant in NE Iran. The present-day shortening rate across the mountain belts of NE Iran is estimated to 5 ± 1 mm yr−1 at about N11°, 2 ± 1 mm yr−1 of NS shortening across the eastern Kopet Dag and 3 ± 1 mm yr−1 of NS shortening across Binalud and Kuh-e-Sorkh. Our GPS measurements emphasize the varying character of the Kopet Dag deformation between its southeastern part with prevailing thrusting at low rates and its northwestern part with dominant strike-slip activity at increasing rates. The principal axes of the horizontal strain tensor appears very homogeneous from the Zagros to the Alborz and the Kopet-Dag (N20°) and in eastern Iran (Makran and Lut block: N30°). Only NW Iran suffers a variable strain pattern which seems to wrap the Caspian basin. The strain tensor map underlines the existence of large homogeneous tectonic provinces in terms of style and amplitude of the deformation. 相似文献
244.
245.
246.
247.
Hamid N. Al-Sadi 《Pure and Applied Geophysics》1973,104(1):439-452
Summary Four spectral parameters, each of which reflects a certain spectral characteristic, are computed for 67 power spectra of earthquakes. The analyzed signals used in this work are theP-phases recorded by short-period, vertical-component seismographs.In correlating the values of the spectral parameters with the respective focal depths, a qualitative spectrum-depth relation is obtained. The most outstanding feature of the relationship thus computed, is a pronounced anomaly in the depth-range of 50–250 km. This is found to correlate rather well with the location of the low-velocity layer which many seismologists have shown to exist in the earth's upper mantle. With the aid of results obtained from experimental work on rock blasts, it is argued that the anomalous zone has more viscous character than the overlying and underlying media.On leave of absence from the Ministry of Oil and Minerals, Baghdad, Iraq 相似文献
248.
Gulati Sneh George Florence Hamid Shahid 《Theoretical and Applied Climatology》2018,131(3-4):1191-1202
Theoretical and Applied Climatology - Rising global temperatures are leading to an increase in the number of extreme events and losses ( http://www.epa.gov/climatechange/science/indicators/ ).... 相似文献
249.
Mokari Esmaiil DuBois David Samani Zohrab Mohebzadeh Hamid Djaman Koffi 《Theoretical and Applied Climatology》2022,147(1-2):575-587
Theoretical and Applied Climatology - Reference evapotranspiration (ET0) is a major factor for water resource management. Although the FAO Penman–Monteith model is the highly recommended for... 相似文献
250.
Hamid M. K. Al-Naimiy Ali A. A. Mutter Hassan A. Flaih 《Astrophysics and Space Science》1985,108(2):227-236
Photoelectric observations of the eclipsing variable β Per, were obtained inUBV standard system, and new elements for the primary minimum were determined as $$J.D. = 2445641.5135,O - C = 0_.^d 0.009.$$ The light curves of the system were analysed using Fourier techniques in the frequency-domain. The fractional radii of both components are $$r_1 = 0.217 \pm 0.002,r_2 = 0.233 \pm 0.002andi = 85.5 \pm 0.5.$$ Absolute elements were derived and the effective temperatures are $$T_1 = 11800K,T_2 = 5140K.$$ 相似文献