全文获取类型
收费全文 | 100篇 |
免费 | 3篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 2篇 |
地球物理 | 14篇 |
地质学 | 40篇 |
海洋学 | 4篇 |
天文学 | 38篇 |
自然地理 | 3篇 |
出版年
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 5篇 |
2016年 | 12篇 |
2015年 | 2篇 |
2014年 | 3篇 |
2013年 | 4篇 |
2012年 | 1篇 |
2011年 | 2篇 |
2010年 | 8篇 |
2009年 | 1篇 |
2008年 | 1篇 |
2007年 | 2篇 |
2006年 | 1篇 |
2005年 | 3篇 |
2004年 | 2篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2001年 | 1篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1993年 | 3篇 |
1991年 | 2篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1986年 | 1篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有103条查询结果,搜索用时 15 毫秒
41.
The present work shows how the new defined value Q can play a role in spectral reclassification of Be stars. 相似文献
42.
Osama M. K. Kassem Habes A. Ghrefat Haider Zaman Awni T. Batayneh Saad Almogren Yousef Nazzal Eslam Elawadi 《Journal of the Indian Society of Remote Sensing》2016,44(1):91-99
Geological and structural mappings of Tayyib Al-Ism area were carried out using the rocks finite strain data, the Landsat-7 Enhanced Thematic Mapper Plus (ETM+) data and the field based observations. To analyze the finite strain in the studied rocks, the Rf /? and Fry methods are applied to feldspar porphyroclasts and mafic grains from nine metavolcano-sedimentary samples (Hegaf Formation), four diorite-gabbros suite samples (Sawawin Complex), two meta-granite samples (Ifal suite) and five Zuhd alkali granite samples. The obtained data indicate traces of high to moderate level of deformation in the meta-granite and metavolcano-sedimentary rocks. The axial ratios along the XZ section range from 1.70 to 4.80 for the Rf/? method and from 1.50 to 4.50 for the Fry method. A sub-vertical trend of short axes in association with sub-horizontal foliation is also observed. These informations allow us to conclude that a finite strain in the deformed granitic rocks is of the same order of magnitude as in the metavolcano-sedimentary rocks. The contacts between the metavolcano-sedimentary and granitic rocks in Tayyib al Ism area were formed during the granitic intrusions along some of the faults under brittle to semi-ductile deformation conditions. These faults have significantly influenced the geometry and style of rifting in the Red Sea during the Neogene. The finite strain was accumulated in the area during the process of deformation, which superimpose the already existed nappe structure. It indicates that the nappe contacts formed during the accumulation of finite strain. In addition to finite strain analysis, band ratio images (3/1, 5/3, 7/5) and Principal Component Analysis (PCA) technique have been used, which proved effective in mapping geological and structural features of various rock bodies exposed in the study area. 相似文献
43.
44.
45.
46.
The frost sensitivity of a rock is resulting from the combined action of processes linked to porous network characteristics (state parameters) and to the way water flows into this porous network (transfer parameters), our study was thus about the influence of these parameters on frost weathering of rocks. Sedimentary rocks often found on buildings (limestone and sandstone) and consequently submitted to temperature variations have been selected. State and transfer parameters have been measured for sample characterization and the follow-up of weathering during freeze–thaw cycles. The coupled influence of a state parameter (dynamic modulus of elasticity) and a transfer parameter (water permeability), i.e. between rock skeletal strength and voids connection, has thus been discussed. 相似文献
47.
Eight subsurface sections and a large number of thin sections of the Mishrif Limestone were studied to unravel the depositional
facies and environments. The allochems in the Mishrif Formation are dominated by bioclasts, whereas peloids, ooids, and intraclasts
are less abundant. The sedimentary microfacies of the Mishrif Formation includes mudstone, wackestone, packstone, grainstone,
floatstone, and rudstone, which have been deposited in basinal, outer shelf, slop followed by shoal reef and lagoonal environments.
The formation displays various extents of dolomitization and is cemented by calcite and dolomite. The formation has gradational
contact with the underlying Rumaila Formation but is unconformably overlain by the Khasib Formation. The unconformity is recognized
because the skeletal grains are dominated by Chaophyta (algae), which denotes the change of environment from fully marine to lacustrine environment. Thus, the vertical bioclast
analysis indicates that the Mishrif Formation is characterized by two regressive cycles, which control the distribution of
reservoir quality as well as the patterns of calcite and dolomite cement distribution. Mishrif Formation gradationally overlies
Rumaila Formation. This was indicated by the presence of the green parts of Chaophyta (algae) as main skeletal grains at the uppermost part of well Zb-47, which refer to lacustrine or fresh water environment.
Petrographical study shows that the fossils, peloids, oolitis, and intraclasts represent the main allochem. Calcite and dolomite
(as diagenetic products) are the predominant mineral components of Mishrif Formation. Fossils were studied as an environmental
age and facial boundaries indicators, which are located in a chart using personal computer programs depending on their distributions
on the first appearance of species. Fifteen principal sedimentary microfacies have been identified in the Mishrif Formation,
which includes lime mudstone, mudstone–wackestone, wackestone, wackestone–packstone, packstone, packstone–grainstone, grainstone–floatstone,
packstone–floatstone, packstone–rudstone, and wackestone–floatstone. Markov chain analysis has been used to study the transitional
pattern of different microfacies types vertically in each well and laterally in all wells as a composite section. The vertical
analysis indicates that the Mishrif Formation characterized by two regressive cycles, the main one started with basinal or
outer shelf environment, slop environment followed by shoal or reefal environment, and ended with a lagoonal environment.
The lateral analysis shows the same regressive cycle, and by using the lithofacies association concepts, we built the depositional
model of the Mishrif Formation environment. 相似文献
48.
S. M. Saad J. Kubát P. Hadrava P. Harmanec P. Koubský P. Škoda M. Šlechta D. Korčáková S. Yang 《Astrophysics and Space Science》2005,296(1-4):173-177
Based on a new set of electronic spectra in a relatively wide spectral range (3500–8300 Å) and using the methods of spectrum disentangling (code KOREL) and solution of RV curves (code FOTEL), we determined new orbital elements of the binary star κ Dra. The solution of the radial velocity curves for Balmer and some other strong metallic lines suggested a circular orbit and led to the following orbital elements: period P = 61.555 ± 0.029 days, epoch of periastron passage T periast = 49980.22 ± 0.59, RV semi-amplitude K 1 = 6.81 ± 0.24 km s?1, and a mass function of f(m) = 0.002 M ⊙. Lines of the secondary were not detected. In addition, moving absorption bumps in the violet peaks of Hα and Hβ lines were found to be phase-locked with the orbital period. Their presence suggests some kind of interaction between the binary components. 相似文献
49.
Unsteady free-convection flows near an infinite vertical plate in a rotating medium in the presence of a constant transverse magnetic field are investigated under an arbitrary time-dependent heating of the plate. By using the Laplace transform technique, the Green's function of the problem is determined and exact solutions are obtained for special cases of the time-dependent heating effect. The thermal influence on skin friction at the plate and the displacement thickness of the boundary layer are determined, and the structure of the thermal wave trains is discussed.Formerly Kulshrestha. 相似文献
50.
Zekai Şen Hussam A. Khiyami Saad G. Al-Harthy Faisal A. Al-Ammawi Ali B. Al-Balkhi Mohammed I. Al-Zahrani Hashim M. Al-Hawsawy 《Arabian Journal of Geosciences》2013,6(9):3563-3572
Flood inundation maps are dependent on the topographic and geomorphologic features of a wadi (drainage basin) in arid regions, which are most susceptible for potential flash flood occurrences, such as in the southwestern part of the Kingdom of Saudi Arabia. It is not possible to control the potential flood hazards by using only technological instruments that forewarn the occurrences or imminence. Additionally, it would be better to prepare flood risk maps so as to delineate the risky areas to educate the administrators and local settlers. The availability of these maps is the key requirement for any urban development that entails land use allocation, identification of dam, tunnel, highway, bridge sites, and infrastructure locations for sustainable future. This paper suggests the necessary steps in flood inundation map preparation after determining the possible flood discharge. For this purpose, a set of critical cross-sections along the possible flood plain are taken in the field with surveying methods and measurements. The calculation of the average flow velocity in each section is calculated according to the cross-section geometric, hydraulic, and material properties. Synthetic rating curves (SRC) are prepared for each cross section, which are very useful especially in arid and semi-arid regions where there are no perennial surface water flows for natural rating curve measurements. All the SRCs appear in the form of power function which relates the flow depth to discharge in a given cross section. It is then possible to calculate the flood depth in the cross section through its SRC. Depending on the cross-section shape, the flood width can be calculated. The connection of a series of widths on a scaled topographic map delineates the flood inundation area. If digital elevation map (DEM) is available, then the SRCs can be integrated with these maps and the flood inundation delineation can be achieved automatically. Since DEMs are not available, the topographic maps are used for this purpose in order to delineate flood inundation areas within wadis Hali and Yiba from the southwestern Kingdom of Saudi Arabia. 相似文献