全文获取类型
收费全文 | 170篇 |
免费 | 8篇 |
国内免费 | 6篇 |
专业分类
测绘学 | 4篇 |
大气科学 | 7篇 |
地球物理 | 29篇 |
地质学 | 102篇 |
海洋学 | 12篇 |
天文学 | 10篇 |
综合类 | 7篇 |
自然地理 | 13篇 |
出版年
2022年 | 4篇 |
2021年 | 10篇 |
2020年 | 4篇 |
2019年 | 11篇 |
2018年 | 14篇 |
2017年 | 11篇 |
2016年 | 17篇 |
2015年 | 8篇 |
2014年 | 15篇 |
2013年 | 18篇 |
2012年 | 11篇 |
2011年 | 11篇 |
2010年 | 7篇 |
2009年 | 6篇 |
2008年 | 6篇 |
2007年 | 4篇 |
2006年 | 4篇 |
2005年 | 2篇 |
2004年 | 6篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 3篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有184条查询结果,搜索用时 93 毫秒
101.
Micòl Mastrocicco Giulio Vignoli Nicolò Colombani Nasser Abu Zeid 《Environmental Earth Sciences》2010,61(2):311-322
A portion of an unconfined alluvial aquifer located in the Padana Plain (Italy) was characterized following an integrated
hydro-geophysical approach. Initially an electrical resistivity tomography (ERT) survey was employed to localize the boundaries
of a modest paleo-channel body and to design the installation of a groundwater monitoring network. Multilevel slug-tests were
performed to estimate the aquifer’s saturated hydraulic conductivities. Determined permeability values together with electrical
resistivity data were correlated. The correlation resulted in a site specific bi-logarithmic linear relationship. Based on
this relationship, punctually determined hydraulic conductivities were spatially extended over the studied flow domain. Finally,
continuously measured piezometric heads were used to calibrate a 3D flow model. Sensitivity analysis was performed to confirm
the reliability of the reconstructed permeability field, as well as, to assess the minimum number of direct measurements needed
to safely characterize the selected aquifer portion. The integration of the ERT survey results with the classical hydrogeological
tests can be conveniently applied to constrain the permeability field during flow model calibration. Although the applicability
of the determined relationship is site specific, the followed procedure is useful especially when there is a need to optimize
the available resources and in case of small-scale pilot studies. 相似文献
102.
Al-Najjar Tariq Wahsha Mohammad Al-Khushman Mwaffaq Khalaf Maroof Hardage Kyle Hayek Wissam Khadra Khalid Abu Paytan Adina 《Ocean Science Journal》2021,56(4):364-377
Ocean Science Journal - To assess the utility of the seagrass (Halophila stipulacea) for biomonitoring of metal pollution, seagrass samples were collected from four sites along the Jordanian coast... 相似文献
103.
The astrophysical S-factor of the experimental cross section data of the main reactions in the proton–proton chain, i.e. 3He(3He,2p)4He, 3He(4He,γ)7Be and 7Be(p,γ)8B, are reanalyzed by using the exact tunneling probability in nuclear reactions. Our goal is to test this treatment in finding the reaction rate per pair for non-resonant reactions. At low temperatures, the exact treatment is identical to the standard formalism but diverges at higher temperatures. 相似文献
104.
105.
Humood F. Al‐Mudhaf Mustafa I. Selim Aleksander M. Astel Abdel‐Sattar I. Abu‐Shady 《洁净——土壤、空气、水》2011,39(9):833-843
The present study reveals spatial variability of haloacetic acids and the basic physiochemical properties of drinking water samples through visualization based on the Kriging algorithm and hierarchical cluster analysis. Both projection and statistical method contributed to the logical classification of the indoor and outdoor water samples collected from various governorates covering more than 95% of the residential areas in Kuwait. Clustering of the variables led to the formation of several significant clusters corresponding to the effect of chlorine concentration and its residence time on the formation potential of chlorinated acetic acid derivatives in desalinated drinking water as well as to the total ionic composition of water samples and to the effect of the formation of brominated acetic acid derivatives. Clustering of samples, both indoor and outdoor, indicated that all of governorates located in the northern part of Kuwait are supplied with water containing high concentrations of chlorinated acetic acid derivatives, whereas significantly lower amounts of chlorinated or monobrominated acetic acids were found in water samples in the central and southern parts of the country. 相似文献
106.
Humood F. Al‐Mudhaf Mohammad N. Al‐Hayan Mustafa I. Selim Abdel‐Sattar I. Abu‐Shady 《洁净——土壤、空气、水》2011,39(12):1068-1080
Three hundred and twenty‐two samples of desalinated household water were collected from 99 sampling locations that covered 95% of Kuwaiti's residential areas. Seventy‐one brands of bottled water were collected from Kuwaiti markets. The water quality parameters that were studied included pH, electrical conductivity (EC), total dissolved solids (TDS), F?, Cl?, Br?, , , , , , , , and the major macronutrients Na+, K+, Ca2+, and Mg2+. The analysis yielded a large range of results for most of these parameters, with differences in some cases exceeding 10‐fold. With a few exceptions, the results were found to comply with US‐EPA and WHO standards. Only the water in two brands of bottled water was acidic (pH < 6.5). The TDS was found to be higher than the US‐EPA regulated value in 4 and 3% of the household samples and bottled water brands, respectively. The fluoride levels were generally higher in bottled water than in household water. However, the household water that was produced by the Doha desalination plant and some of the European brands of bottled water were the best samples studied in terms of their quantity of Ca2+, Mg2+, and Na+ compared with the DRI values for those substances. EC and TDS were positively correlated with , , Na+, K+, Ca2+, and Mg2+ for household water but only with Ca2+ and Mg2+ for bottled water. 相似文献
107.
Béatrice Michot Ehab A. Meselhe Victor H. Rivera-Monroy Carlos Coronado-Molina Robert R. Twilley 《Estuarine, Coastal and Shelf Science》2011
Taylor Slough is one of the natural freshwater contributors to Florida Bay through a network of microtidal creeks crossing the Everglades Mangrove Ecotone Region (EMER). The EMER ecological function is critical since it mediates freshwater and nutrient inputs and controls the water quality in Eastern Florida Bay. Furthermore, this region is vulnerable to changing hydrodynamics and nutrient loadings as a result of upstream freshwater management practices proposed by the Comprehensive Everglades Restoration Program (CERP), currently the largest wetland restoration project in the USA. Despite the hydrological importance of Taylor Slough in the water budget of Florida Bay, there are no fine scale (∼1 km2) hydrodynamic models of this system that can be utilized as a tool to evaluate potential changes in water flow, salinity, and water quality. Taylor River is one of the major creeks draining Taylor Slough freshwater into Florida Bay. We performed a water budget analysis for the Taylor River area, based on long-term hydrologic data (1999–2007) and supplemented by hydrodynamic modeling using a MIKE FLOOD (DHI, http://dhigroup.com/) model to evaluate groundwater and overland water discharges. The seasonal hydrologic characteristics are very distinctive (average Taylor River wet vs. dry season outflow was 6 to 1 during 1999–2006) with a pronounced interannual variability of flow. The water budget shows a net dominance of through flow in the tidal mixing zone, while local precipitation and evapotranspiration play only a secondary role, at least in the wet season. During the dry season, the tidal flood reaches the upstream boundary of the study area during approximately 80 days per year on average. The groundwater field measurements indicate a mostly upwards-oriented leakage, which possibly equals the evapotranspiration term. The model results suggest a high importance of groundwater contribution to the water salinity in the EMER. The model performance is satisfactory during the dry season where surface flow in the area is confined to the Taylor River channel. The model also provided guidance on the importance of capturing the overland flow component, which enters the area as sheet flow during the rainy season. Overall, the modeling approach is suitable to reach better understanding of the water budget in the mangrove region. However, more detailed field data is needed to ascertain model predictions by further calibrating overland flow parameters. 相似文献
108.
Helmy S. O. Abouelnaga Hassan El-Shayeb Saleh E. Ammar Haridy M. M. Haridy Atef Abu Donia 《Arabian Journal of Geosciences》2014,7(4):1577-1586
Gabal El Sela area lies in the extreme southeastern part of the eastern desert in Egypt. It is covered by basement rocks of different compositions. The detailed work in this area covers about 4 km2 and it is represented mainly by coarse younger granite as a curved shape extended in NE–SW direction and dissected by many faults in various trends; some of them are invaded by dykes especially the lamprophyre dykes in the ENE–WSW trend. Detailed geological, structural, and radiometric investigations are carried out on the area. The radiometric data are statistically analyzed and the results show that the total count radiometric map reflects six separate anomalies. The field work revealed that four anomalies are related to lamprophyre dykes, the other two anomalies are structurally controlled by NE–SW and E–W faults. These anomalies are followed by some trenches which traced and measured in detail exhibiting the possible extension of these anomalies with depth. These measurements show that lamprophyre dyke has the highest reading of radioactivity, it reaches 270 Ur in the surface and to 6,300 in the trenches. While the granite of the sela area is considered possesses high level of radioactivity, where its radioactivity ranges from 19.9 to 81 Ur with an average of about 32 Ur. 相似文献
109.
Muhammad Nauman Malik Mehdi Murtuza Iqbal Asif Bakar Muhammad Saifullah Abu Brahim Aissa Dk Nur Afiqah Jalwati Puteri Amer Farhan Rafique 《地下水科学与工程》2014,7(4):373-382
In many circumstances involving heat and mass transfer issues, it is considered impractical to measure the input flux and the resulting state distribution in the domain. Therefore, the need to develop techniques to provide solutions for such problems and estimate the inverse mass flux becomes imperative. Adaptive state estimator (ASE) is increasingly becoming a popular inverse estimation technique which resolves inverse problems by incorporating the semi-Markovian concept into a Bayesian estimation technique, thereby developing an inverse input and state estimator consisting of a bank of parallel adaptively weighted Kalman filters. The ASE is particularly designed for a system that encompasses independent unknowns and /or random switching of input and measurement biases. The present study describes the scheme to estimate the groundwater input contaminant flux and its transient distribution in a conjectural two-dimensional aquifer by means of ASE, which in particular is because of its unique ability to efficiently handle the process noise giving an estimation of keeping the relative error range within 10% in 2-dimensional problems. Numerical simulation results show that the proposed estimator presents decent estimation performance for both smoothly and abruptly varying input flux scenarios. Results also show that ASE enjoys a better estimation performance than its competitor, Recursive Least Square Estimator (RLSE) due to its larger error tolerance in greater process noise regimes. ASE’s inherent deficiency of being slower than the RLSE, resulting from the complexity of algorithm, was also noticed. The chosen input scenarios are tested to calculate the effect of input area and both estimators show improved results with an increase in input flux area especially as sensors are moved closer to the assumed input location. 相似文献
110.
The Jajiya Member of Jaisalmer Formation yielded a foraminiferal assemblage comprising twenty-three species dominated by the family Vaginulinidae. An Oxfordian age is assigned to the foraminiferal assemblage based on the record of some characteristic Oxfordian species reported from different parts of the world. The foraminiferal assemblage suggests an open marine shelf environment of deposition. 相似文献