全文获取类型
收费全文 | 114篇 |
免费 | 3篇 |
国内免费 | 5篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 10篇 |
地球物理 | 26篇 |
地质学 | 66篇 |
海洋学 | 6篇 |
天文学 | 7篇 |
综合类 | 1篇 |
自然地理 | 4篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 10篇 |
2017年 | 5篇 |
2016年 | 5篇 |
2015年 | 9篇 |
2014年 | 7篇 |
2013年 | 8篇 |
2012年 | 4篇 |
2011年 | 3篇 |
2010年 | 8篇 |
2009年 | 9篇 |
2008年 | 1篇 |
2007年 | 6篇 |
2006年 | 3篇 |
2005年 | 2篇 |
2004年 | 3篇 |
2003年 | 1篇 |
2002年 | 4篇 |
2001年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1974年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1965年 | 2篇 |
排序方式: 共有122条查询结果,搜索用时 17 毫秒
61.
Mohammad Abou Romieh Rob Westaway Mohamad Daoud Yousef Radwan Rayan Yassminh Ahlam Khalil Abeer Al‐Ashkar Susan Loughlin Katherine Arrell David Bridgland 《地学学报》2009,21(6):427-437
The Africa–Arabia plate boundary comprises the Red Sea oceanic spreading centre and the left‐lateral Dead Sea Fault Zone (DSFZ); however, previous work has indicated kinematic inconsistency between its continental and oceanic parts. The Palmyra Fold Belt (PFB) splays ENE from the DSFZ in SW Syria and persists for ~400 km to the River Euphrates, but its significance within the regional pattern of active crustal deformation has hitherto been unclear. We report deformation of Euphrates terraces consistent with Quaternary right‐lateral transpression within the PFB, indicating anticlockwise rotation (estimated as 0.3° Ma?1 about 36.0°N 39.8°E) of the block between the PFB and the northern DSFZ relative to the Arabian Plate interior. The northern DSFZ is shown to be kinematically consistent with the combination of Euler vectors for the PFB and the Red Sea spreading, resolving the inconsistency previously evident. The SW PFB causes a significant earthquake hazard, previously unrecognized, to the city of Damascus. 相似文献
62.
A simplified computational technique based on a refined global–local method is applied to the failure analysis of concrete structures. The technique distinguishes the scale of the structure, modelled with large size finite elements, from the scale at which material non‐linearity occurs due to progressive cracking and macro‐crack propagation. The finite element solution is split into two parts: a linear elastic analysis on a coarse mesh over the entire structure and a non‐linear analysis over a small part of the structure where a dense finite element grid is employed. In the non‐linear calculation, a non‐local damage model is implemented. These two computations are coupled with the help of an iterative scheme. The size and location of the region where a non‐linear analysis is performed, is adapted to follow the development of the damage zone. Numerical examples of mode I fracture of concrete specimens with straight and curved cracks are presented. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
63.
Majdi Al-Mahasneh Mohamad Al-Widyan Hussein Ababneh Taha Rababah Khalil Ereifej 《Natural Resources Research》2008,17(1):13-20
Grain dust is a by-product produced in large quantities from grain storage and milling facilities but as of yet is treated
as waste locally and regionally. Based on the conviction that material properties determination is a necessary first step
for the efficient handling, processing, and use of materials, this work was initiated with the purpose of characterizing grain
dust in terms of its physicochemical and thermal properties.
Grain dust as a special waste material is a complex, dry, grey powder, composed mainly of grain chips, soil, whole wheat and
barley seeds, and straw. The material was found to have a bulk density of 362 kg/m3, specific heat, thermal conductivity, and gross calorific value were 1540 J/kg K, 0.27 W/m K, and 4120 kJ/kg, respectively.
Nutritional composition showed low concentrations of protein, and ether extract, and high concentrations of carbohydrates,
ash, and crude fiber. Mineral analysis showed that Ca, Fe, and K were available in significant amounts ranging from 30 to
135 ppm.
The as-received material is dry enough to be stored very safely and burned for energy production in either its loose form
or as pellets. Moreover, adjustments to the ash content and C:N ratio of the material deems it a promising candidate as an
animal feed and as a substrate for composting and biogasification. 相似文献
64.
Surface sediments along the Rimouski section in the St. Lawrence estuary were sampled at the surface and at 10 cm depth. Fatty acids were extracted and analysed. Saturated and unsaturated fatty acid contents at the two depths vary with the nature of the sediments. The clay sediments rich in organic matter contain more fatty acids than the corresponding sand or gravel. Unsaturated fatty acids were more abundant in the surface sediments. Some iso- and anteiso-odd carbon fatty acids were detected in the sediments; these acids could indicate a microbial activity. Correlation is made with the fatty acid contents of the water column together with the surface microlayer of the estuarine water. 相似文献
65.
Evaluation of Jordanian faujasite tuff by comparison with other natural and synthetic zeolites 总被引:1,自引:0,他引:1
Khalil M. Ibrahim 《Environmental Geology》2001,40(4-5):440-445
The evaluation of the Jordanian faujasite tuff in wastewater treatment is investigated by comparison with synthetic faujasite
(13X) and clinoptilolite-rich tuff. The material used (JORD-FAUJ) is concentrated by mineral processing techniques. It has
a faujasite content of 57% and phillipsite content of 35%. Thorough characterization of the JORD-FAUJ revealed the high suitability
of the product for use in column operation. It either compares closely or gives better thermal stability, attrition resistance,
acid resistance, cation exchange capacity (CEC) and water absorption capacity, when compared with products already recommended
in column operation. The study has also revealed that the JORD-FAUJ competes efficiently in ammonium removal with the synthetic
faujasite 13X and clinoptilolite-rich tuff and gives similar performance. JORD-FAUJ gave a very high performance in removing
Pb, Cr, Cu, Zn, and Ni from wastewater, equivalent to 83–100% of that of faujasite 13X and much higher than the clinoptilolite-rich
tuff.
Received: 13 April 2000 · Accepted: 1 August 2000 相似文献
66.
A cluster of well-preserved recent volcanoes in the northern Bayuda Desert make up a more or less continuous field some 520 km2 in area surrounded by a number of isolated centres of eruption. The volcanoes are numerous but small; up to 400 m in height and 0.35 km2 in volume. Most of them are simple composite volcanoes with a pyroclastic cone skirted by a small lava field erupted from the same vent after explosive eruptions had ceased. In a few instances, however, the cone was eviscerated by more violent eruptions, leaving a deep explosion crater. The lavas are all nepheline-normative alkali basalts and contain a variety of xenocrysts and xenoliths from at least three different sources. The distribution of the recent volcanoes was partly controlled by large granitic ring-intrusions of the Basement Complex country rocks. These intrusions belong to the Younger Granite association of late Precambrian or Lower Palaeozoic age and represent a volcanic-intrusive episode widespread in northern Africa. The complexes are composed of cale-alkaline and peralkaline granites and syenites and a related plexus of dyke swarms. 相似文献
67.
Summary A flat plate heat collector was constructed for the purpose of heating water by solar energy. It was erected facing south, tilted to the horizontal at the optimum tilt angle, and tested under the weather conditions typical to the U.A.R., for the different rates of flow. It was found, for the dimensions of the collector (0.8 m2) that the best rate of flow is about 12 l/h and that the corresponding rise in the temperature of the flowing water is about 40° C. The overall heat transfer coefficient and the efficiency of the collector were investigated. On the average, when the rate of flow ranges between 5 and 12 l/h, the efficiency was found to be about 45 percent. 相似文献
68.
Summary Measurements of the total solar radiation at normal incidence, undertaken at Helwan Observatory, on every clear day and for a period of 10 years, have been studied in terms of the air mass and the sun's altitude. These measurements together with the data available in the literature on diffuse radiation, have led to the evaluation of the hourly rates of total solar radiation on vertical surfaces and south facing surfaces inclined to the horizontal at different tilt angles. 相似文献
69.
The Nuweibi albite granite is one of 14 known Sn-Ta-Nb bearing granitoids in the Eastern Desert region of Egypt. The granite
is a highly leucocratic, albite-rich rock with accessory columbite-tantalite, cassiterite, microlite and ixiolite as well
as topaz, garnet and white mica. Ages of 450–600 Ma were obtained from zircons by the 207Pb/206Pb evaporation method. Great uncertainty is caused by the small size and poor quality of the grains, but the precision is
sufficient to indicate that the granite is late- or postorogenic with respect to the Panafrican orogeny. The Nuweibi granite
is divided into a western and an eastern part by a regional fault. Both parts of the granite are compositionally similar but
there are important differences and a clear compositional gap between them, so they are considered separate facies of an intrusive
complex. The eastern part of the granite is more highly mineralized, has higher modal albite contents and higher Ta/Nb ratios,
both in the whole rock and in the ore minerals. It is suggested that the two parts of the granite evolved from a common source
and were emplaced sequentially, the eastern part representing a later, more fractionated magma. Textural evidence strongly
suggests that the granite has a magmatic origin overall, but disturbance of geochemical trends at the whole-rock scale and
at the scale of zoning profiles in individual grains of columbite-tantalite indicate post-magmatic overprinting. By analogy
with other Ta-bearing albite granites, the sodic bulk composition of the Nuweibi granite can be explained by fluorine enrichment
in the magma. Fluorine contents in the magma were high enough to stabilize topaz, and muscovites contain 2–4 wt.%. F. However,
whole-rock F contents are low. We speculate that the low Ca, Al and P contents of the magma prevented abundant F-bearing minerals
to form and led to loss of fluorine to now-eroded roof rocks.
Received: 8 November 1995 / Accepted: 10 June 1996 相似文献
70.
The Ghouri area in southwest Iran exposes a cross section through the Zagros orogenic belt. The area provides an opportunity to investigate quantitative finite strain (Rs), kinematic vorticity number (Wk), proportions of pure shear and simple shear components, sense of shear indicators, steeply plunging lineations, and other moderate to steeply plunging stretching lineations in a transpressional zone. Based on a classical strain analysis of deformed microfossils with oblate strain ellipsoid shape, the Zagros orogenic belt is classified as a pure-shear dominated zone of transpression, but asymmetry of shear-sense indicators suggests that a significant component of simple shear was involved along the deformation zone boundaries. The long axes of the microfossils and stretched pebbles of a deformed conglomerate were used to indicate the stretching direction in this zone. The stretching lineations have a steep to moderate plunge but a constant strain magnitude. Characteristics of dextral inclined transpressional kinematics in the Zagros continental collision zone were quantified and indicate an estimated k-value < 1, an angle between the maximum horizontal axis of the instantaneous strain ellipsoid and the zone boundary (θ = 32°), asymmetrical dextral shear-sense indicators, and an angle of relative plate motion (α = 25°). 相似文献