全文获取类型
收费全文 | 71篇 |
免费 | 6篇 |
国内免费 | 2篇 |
专业分类
大气科学 | 2篇 |
地球物理 | 16篇 |
地质学 | 42篇 |
海洋学 | 5篇 |
天文学 | 4篇 |
综合类 | 1篇 |
自然地理 | 9篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 1篇 |
2020年 | 5篇 |
2018年 | 7篇 |
2017年 | 2篇 |
2016年 | 11篇 |
2015年 | 4篇 |
2014年 | 8篇 |
2013年 | 5篇 |
2012年 | 1篇 |
2011年 | 3篇 |
2010年 | 4篇 |
2009年 | 2篇 |
2008年 | 4篇 |
2007年 | 1篇 |
2006年 | 2篇 |
2004年 | 4篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1997年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有79条查询结果,搜索用时 140 毫秒
51.
Nur Mun’im Mohd Han Mohd Talib Latif Murnira Othman Doreena Dominick Noorlin Mohamad Hafizan Juahir Norhayati Mohd Tahir 《Environmental Earth Sciences》2014,72(3):849-859
This study was carried out in order to determine the concentration of heavy metals, e.g., lead (Pb), cadmium (Cd), copper (Cu), zinc (Zn), iron (Fe), manganese (Mn), nickel (Ni) and chromium (Cr) in road dust in Kuala Lumpur’s city centre. Samples were collected from four sampling locations, each of which had four sampling points and three replications. Heavy metals from different fractions of particles separated by different diameter sizes: d < 63 μm (Fraction A), 63 < d < 125 μm (Fraction B) and 125 < d < 250 μm (Fraction C) were analyzed using inductively coupled plasma mass spectrometry. The results from this study showed that concentration of heavy metals was dominated by the smallest particle size: <63 μm and that Fe was the most abundant heavy metal overall, followed by Cu > Mn > Zn > Pb > Ni > Cr > Cd. The fact that Cd had the highest enrichment factor value (EF) for all particle sizes indicates that anthropogenic activities contributed to the presence of this metal. There was also a higher EF value for heavy metals in small particle (Fraction A), compared to Fraction B and C, which suggests that fine particles were being produced through anthropogenic activities. Cluster analysis and principal component analysis demonstrated the likelihood of the heavy metals detected in the road dust, originating from road traffic and industrial activities. 相似文献
52.
This paper explores the dynamics of Gödel-type geometry for tilted and non-tilted congruences. The kinematical as well as dynamical quantities are investigated for both congruences with non-vanishing nature of vorticity vector. The obtained vorticity is of kinematical type, i.e., not produced by a circular flow of superenergy on the plane orthogonal to the vorticity vector. We conclude that super-Poynting vector is non-zero for the tilted congruence linked with heat flux of fluid distribution while it vanishes in non-tilted case. 相似文献
53.
Correlated ion stopping of charged debris resulting from the fragmentation of energetic cluster ions focussed on Au foam converters is considered for driving indirectly a thermonuclear capsule. The 1D simulation of converter time evolution demonstrates a very high conversion efficiency of projectile energy into hard X-ray photons building up a very hot (Tr > 300 eV) thermal bath. Intense and energetic cluster ion beams thus demonstrate considerable potential as a novel driver for inertial confinement fusion. 相似文献
54.
Hassan Mujtaba Tahir Aziz Khalid Farooq Nagaratnam Sivakugan Braja M. Das 《Journal of the Geological Society of India》2018,92(3):357-362
Improvement in engineering properties of expansive soils by mixing ground granulated blast furnace slag (GGBFS) is the main focus of this research. For this purpose two expansive soil samples were collected from DG Khan and Sialkot areas (Pakistan). Classification tests revealed that DG Khan sample belonged to fat clay (CH) while Sialkot soil was lean clay (CL) as classified by Unified Soil Classification System. GGBFS has been added in varying proportions between 0 and 55% in these soil samples to study its role in stabilizing these expansive soils. Based on the laboratory test performed on composite soil samples, it was observed that maximum dry unit weight increased up to 10 % by adding 50% GGBFS in both samples. California bearing ratio (CBR) value showed an increase from 3.2 % to 11.5% for DG Khan soil while CBR values varied from 2.4% to 10.7% for Sialkot soil by mixing 50% GGBFS. Addition of 30 % GGBFS to DG Khan soil reduced swell potential from 8 % to 2 % while in Sialkot soil, 20 % addition of GGBFS reduced swell potential from 5 % to 2 %. Unconfined compressive strength of remoulded sample cured for 28 days increased by about 35% with the addition of 30%GGBFS. The results indicated that mixing of GGBFS in the expansive soil samples have a marked increase in their engineering properties. Also, it is an affective and environmental friendly means to dispose waste of steel industry. 相似文献
55.
Muhammad Rizwan Shafaqat Ali Tahir Abbas Muhammad Zia ur Rehman Mohammad I. Al-Wabel 《Arabian Journal of Geosciences》2018,11(20):630
Cadmium (Cd) is the family member of toxic heavy metals, and its accumulation in food crops has become a global environmental constraint. Biochar potentially minimizes the metal contents in plants, but limited work has been reported on its residual effect on subsequent crops. The residual effect of various biochar levels (0, 1.5, 3.0, and 5.0% w/w) on Cd accumulation in rice has been investigated in this study. Biochar treatments enhanced the rice growth, photosynthesis, and antioxidant enzymes, whereas diminished the Cd contents and oxidative stress in rice. Cadmium concentration in shoots decreased by 24.4, 36.6, and 57.5% in 1.5, 3.0, and 5.0% biochar treatments over the control. Biochar supply enhanced the soil pH and electrical conductivity, whereas diminished the soil bioavailable Cd. Overall, the results depicted a significant residual impact of rice straw biochar on rice growth attributes and Cd uptake. However, studies are still needed to explore the long-term sustainability of biochars prepared from different feedstocks on bioavailability of toxic metals in soils and uptake by food crops under field conditions. 相似文献
56.
N. A. Tahir T. Stöhlker A. Shutov I. V. Lomonosov V. E. Fortov M. French N. Nettelmann R. Redmer A. R. Piriz C. Deutsch 《Astrophysics and Space Science》2011,336(1):61-65
Development of ultra-high power lasers has lead to the very interesting and important field of Laboratory Astrophysics. Recent
progress and expected near future developments in the technology of strongly bunched intense particle beams has opened up
the possibility of studying planetary interiors in the laboratory which hopefully will eventually converge in the new field
of Laboratory Planetary Physics. GSI Helmholzzentrum für Schwerionenforschung, Darmstadt is a well known laboratory worldwide
due to its unique particle accelerator facilities. Construction of the new huge accelerator complex, the Facility for Antiprotons
and Ion Research (FAIR), will substantially improve the existing capabilities of the GSI. A dedicated program named, HEDgeHOB,
that aims to study different problems in High Energy Density (HED) Physics at the FAIR facility, has been proposed. One of
these proposed experiments LAPLAS (LAboratory PLAnetary Science), aim to study materials at extreme conditions as relevant
for the interiors of giant planets. In this paper we present simulation results that show that various regions of the high-pressure
phase diagram of water can be probed within the LAPLAS experiments. For instance, the plasma and the superionic phase are
predicted to occur in the interior of water-rich planets such as Uranus and Neptune as well as in extrasolar planets such
as GJ 436b. 相似文献
57.
Bijay Kumar Pokhrel Pierre Chevallier Vazken Andréassian Adnan Ahmad Tahir Yves Arnaud Luc Neppel 《水文科学杂志》2013,58(8):1507-1518
AbstractThe glaciers in the Nepalese Himalayas are retreating due to rising temperatures. Lack of data and information on Nepal’s cryosphere has impeded scientific studies and field investigations in the Nepalese Himalayas. Therefore, IRD France and Ev-K2 CNR Italy have conducted the PAPRIKA (CryosPheric responses to Anthropogenic PRessures in the HIndu Kush-Himalaya regions: impacts on water resources and society adaptation in Nepal) project in Nepal with the financial support of the French and Italian scientific agencies. This project aims to address the current and future evolution of the cryosphere in response to overall environmental changes in South Asia, and its consequences for water resources in Nepal. Thus, two hydrological models, the GR4J lumped precipitation–runoff model and the snowmelt runoff model (SRM), were used in the Dudh Koshi basin. The GR4J model has been successfully applied in different parts of Europe. To obtain better results in such a harsh and rugged topography, modifications needed to be made, particularly in the snow module. The runoff pattern is analysed herein both for past years and, in a sensitivity analysis, for possible future climatic conditions (i.e. precipitation and temperature) using the SRM and GR4J modelling approaches. The results reveal a significant contribution of snow- and glacier-melt to runoff, and the SRM model shows better performance in Nepalese catchments than the GR4J model.
Editor D. Koutsoyiannis; Associate editor D. Gerten 相似文献
58.
59.
Limestone and clay samples were collected from Darukhula and adjoining areas of the Nizampur District Nowshera, N.W.EE, Pakistan, and analyzed for different parameters in order to search for new reserves of suitable material for the manufacture of different types of cements in N.W.F.P. It was found that the area under study contains three types of limestones, including high grade limestone, Darukhula limestone and siliceous limestone, which contain 53%, 49.03% and 45.19% CaO, respectively, and three types of clay, including maroon color, yellow to yel- lowish-green color and green color clay containing 57.76%, 65.47% and 61.24% SiO2, respectively. Chemical analysis of the limestone and clay samples collected from the deposits in the area under study showed that all the elements found in these samples are within the range of permissible limits for the production of high-strength Portland cement, sulphate resisting cement and white cement. This paper covers the detailed version of the potential raw material deposits at Darukhula and adjoining areas of the Nizampur District. 相似文献
60.
Complexation of metal ions by organic matter is frequently considered to play a part in metal ion dissolution in natural waters. A field study of a relatively unperturbed stream, high in organics, associates this with the fraction related to soil organic acids (humic acids). The association might have two origins. The first is complexation. However, well known sequences of complexing tendency do not predict the behaviour. A better theory uses the additional factor of the reducing capacity of dissolved organic matter toward Fe(III) and Mn(IV). 相似文献