全文获取类型
收费全文 | 187篇 |
免费 | 14篇 |
国内免费 | 8篇 |
专业分类
测绘学 | 9篇 |
大气科学 | 19篇 |
地球物理 | 36篇 |
地质学 | 87篇 |
海洋学 | 12篇 |
天文学 | 30篇 |
综合类 | 7篇 |
自然地理 | 9篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 6篇 |
2020年 | 5篇 |
2019年 | 1篇 |
2018年 | 21篇 |
2017年 | 16篇 |
2016年 | 21篇 |
2015年 | 9篇 |
2014年 | 12篇 |
2013年 | 15篇 |
2012年 | 4篇 |
2011年 | 8篇 |
2010年 | 7篇 |
2009年 | 8篇 |
2008年 | 3篇 |
2007年 | 4篇 |
2006年 | 3篇 |
2005年 | 8篇 |
2004年 | 7篇 |
2003年 | 3篇 |
2002年 | 1篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1996年 | 1篇 |
1995年 | 5篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1982年 | 2篇 |
1980年 | 4篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 3篇 |
排序方式: 共有209条查询结果,搜索用时 625 毫秒
161.
Naseer Shah Haq Tanveer Ul Khan Abdullah Tanoli Javed Iqbal Khan Nangyal Ghani Qaiser Faizan-ur-Rehman Shah Syed Tallataf Hussain 《Natural Hazards》2021,106(1):965-989
Natural Hazards - The Landslide happens in mountainous regions due to the catastrophe of slope through intensive rain and seismicity. The Himalayas is one of the susceptible parts of the world in... 相似文献
162.
Numerical simulations of shake-table experiment for dynamic soil-pile-structure interaction in liquefiable soils 总被引:5,自引:4,他引:1
A shake-table experiment on pile foundations in liquefi able soils composed of liquefi able sand and overlying soft clay is studied. A three-dimensional(3D) effective stress fi nite element(FE) analysis is employed to simulate the experiment. A recently developed multi-surface elasto-plastic constitutive model and a fully coupled dynamic inelastic FE formulation(u-p) are used to model the liquefaction behavior of the sand. The soil domains are discretized using a solid-fl uid fully coupled(u-p) 20-8 noded brick element. The pile is simulated using beam-column elements. Upon careful calibration, very good agreement is obtained between the computed and the measured dynamic behavior of the ground and the pile. A parametric analysis is also conducted on the model to investigate the effect of pile-pinning, pile diameter, pile stiffness, ground inclination angle, superstructure mass and pile head restraints on the ground improvement. It is found that the pile foundation has a noticeable pinning effect that reduces the lateral soil displacement. It is observed that a larger pile diameter and fi xed pile head restraints contribute to decreasing the lateral pile deformation; however, a higher ground inclination angle tends to increase the lateral pile head displacements and pile stiffness, and superstructure mass seems to effectively infl uence the lateral pile displacements. 相似文献
163.
164.
Natural Hazards - The paper illustrates the results of regional flood frequency analysis of eleven sites of the four major rivers of Punjab, Pakistan. The discordancy measure (D i ) shows that none... 相似文献
165.
Ali AAMIR Ullah MATEE Hussain MATLOOB Asher Samuel BHATTI Rehman KHAISTA 《《地质学报》英文版》2017,91(6):2180-2199
The successful exploration and production of shale-gas resources in the United States and Canada sets a new possible solution towards the energy crisis presently affecting most countries of Asia. This study focuses on the use of well log and 2D seismic data for the characterization of the shale oil/gas potential of a Paleocene–Eocene succession — the Meyal area in the Potwar Basin of Pakistan. Two shaly plays are identified in Paleocene–Eocene strata in well logs using ΔLogR and modified ΔLogR cross-plot techniques. The results indicate that Paleocene shale(the Patala Formation) and the lower shaly part of Eocene limestone(Sakesar Formation) can be potentially mature source rocks. However, the thermal maturity modelling proves that only the Paleocene shale is mature. Our results also suggest that the maturity responses on ΔLogR models for the lower shaly part of the Eocene limestone are due to trapped hydrocarbons in the intra-formational fractures. Petroelastic/petrophysical analysis of the Patala Formation reveals two potential shale oil/gas zones on the basis of Young's modulus, Poisson's ratio, Brittleness index and Total Organic Content at an exploitation depth of 3980–3988 m. This work can provide valuable insight for estimating shale oil/gas potential in highly deformed basins not only in Asia but in other parts of the world. 相似文献
166.
167.
Like other Asian countries, Pakistan is facing the issue of air pollution due to rapid urbanization, enormous transportation increases, and other related human activities. Moreover, continuously increasing emission sources have not only raised pollutant concentrations but also their types, thus damaging both human health and the environment. Faisalabad is the third largest megacity of Pakistan and its state of air quality is getting worse due to factors such as industrialization, high traffic volumes, and extensive fossil‐fuel‐burning activities. This review article aims to highlight the present status of air pollution in this city with special reference to particulate matter, elemental profiles, gaseous pollutants, organic–inorganic particulate contents as well as their sources. The concentration levels of these entities were also compared with other national and international cities, and related environmental standards. It is found that current levels of these pollutants are beyond safety limits as specified by various environment protection agencies and organizations. Several weak aspects and gaps are also identified along with suggestions for improvements of the present situation and directions for future research. 相似文献
168.
The economic value of marine fisheries can be measured by the resource rent that may potentially be earned, which represents a flow of real wealth for the community at large. For the island state of the Maldives we estimate that the resource rent that could be generated by the marine fisheries is in the order of $50 million per annum, constituting some 27% of the current value of landings. This rent is lost due to the de facto open-access nature of fishing. A wealth-based approach to fisheries management would seek to capture the rent, and the paper discusses the constraints and trade-offs that would be faced in applying this in the Maldivian context. We argue that such an approach is entirely consistent with the aim of the 7th National Development Plan which rightly emphasises the need to ensure the sustainability of marine resources for present and future generations. 相似文献
169.
170.
Iron and chromium doped titanium dioxide nanotubes for the degradation of environmental and industrial pollutants 总被引:1,自引:1,他引:0
S. T. Hussain Ph.D. A. Siddiqa 《International Journal of Environmental Science and Technology》2011,8(2):351-362
Pure titanate nanotubes and titanate nanotubes doped with iron (III) and chromium (III) were fabricated by the hydrothermal treatment in methanol and sodium hydroxide mixture. The fabricated nano tubes have high surface area, high aspect ratio, consisted of very good surface morphology and high metals dispersion. The morphology, crysralline phase, composition were characterized by powdered X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Barrett-Joyner-Halenda methods and X-ray photoelectron spectroscopy. The results showed that nanotubes possess anatase phase and are composed up of 8–12 nm in diameter and 360–400 nm in length. The band gap of the titanium dioxide nanotubes was determined using transformed diffuse reflectance spectroscopy according to the Kubelka-Munk theory, showed pronounced band gap decrease on doped titanium dioxide nanotubes. The photocatalytic activity of doped nanotubes were evaluated in terms of degradation of phenol and photoreduction of carbon dioxide into methanol and ethanol under Ultra violet and Infra red irradiation. It was found that with iron (III) and chromium (III) doped titanium dioxide nanotubes exhibited much higher photocatalytic activity than undoped titanate nanotubes. 相似文献