全文获取类型
收费全文 | 131篇 |
免费 | 3篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 4篇 |
地球物理 | 23篇 |
地质学 | 71篇 |
海洋学 | 7篇 |
天文学 | 1篇 |
综合类 | 1篇 |
自然地理 | 27篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2019年 | 1篇 |
2017年 | 1篇 |
2016年 | 7篇 |
2015年 | 1篇 |
2014年 | 5篇 |
2013年 | 7篇 |
2011年 | 2篇 |
2010年 | 3篇 |
2009年 | 5篇 |
2008年 | 11篇 |
2007年 | 10篇 |
2006年 | 10篇 |
2005年 | 10篇 |
2004年 | 7篇 |
2003年 | 3篇 |
2002年 | 6篇 |
2001年 | 6篇 |
2000年 | 9篇 |
1999年 | 11篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
排序方式: 共有136条查询结果,搜索用时 125 毫秒
51.
52.
Aquifer vulnerability assessment using the DRASTIC model at Russeifa landfill,northeast Jordan 总被引:1,自引:0,他引:1
Groundwater is inherently susceptible to contamination from anthropogenic activities and remediation is very difficult and expensive. Prevention of contamination is hence critical in effective groundwater management. In this paper an attempt has been made to assess aquifer vulnerability at the Russeifa solid waste landfill. This disposal site is placed at the most important aquifer in Jordan, which is known as Amman-Wadi Sir (B2/A7). The daily-generated leachate within the landfill is about 160 m3/day and there is no system for collecting and treating this leachate. Therefore, the leachate infiltrates to groundwater and degrades the quality of the groundwater. The area is strongly vulnerable to pollution due to the presence of intensive agricultural activity, the solid waste disposal site and industries. Increasing groundwater demand makes the protection of the aquifer from pollution crucial. Physical and hydrogeological characteristics make the aquifer susceptible to pollution. The vulnerability of groundwater to contamination in the study area was quantified using the DRASTIC model. The DRASTIC model uses the following seven parameters: depth to water, recharge, aquifer media, soil media, topography, impact on vadose zone and hydraulic conductivity. The water level data were measured in the observation wells within the disposal site. The recharge is derived based on precipitation, land use and soil characteristics. The aquifer media was obtained from a geological map of the area. The topography is obtained from the Natural Resources Authority of Jordan, 1:50,000 scale topographic map. The impact on the vadose zone is defined by the soil permeability and depth to water. The hydraulic conductivity was obtained from the field pumping tests. The calculated DRASTIC index number indicates a moderate pollution potential for the study area. 相似文献
53.
Soil radon concentration levels in Deir Abu-Said District, Irbid, Jordan were measured for several depths using CR-39 detectors,
in the summer 2004 for six geological formations, namely, Wadi umm ghudran (WG), Wadi esSir “massive” limestone, Amman silicified
limestone (ASL), Al-Hisa phosphatic limestone (AHP), Muwaqqar chalky-marl (MCM), and Basalt. Using a model (Yakovleva in Ann
Geophys 48(1):195–198, 2005) based on the solution of the diffusion equation in the quasi-homogenous approximation, the characteristics of radon transport
were calculated. Radon flux density from the Earth’s surface, the depth Z
eq, at which the equilibrium value of soil radon concentration is reached and the convective radon flux velocity (v) for the different soils are calculated and found to be consistent with similar values presented elsewhere. Calculations
indicate that the soil covering WG has a low radon risk while, on the contrary, AHP has a higher radon risk as expected, since
AHP has higher content of uranium. The other formations have intermediate values. The results of the present study confirm
the statement by Yakovleva (Ann Geophys 48(1):195–198, 2005) that two measurements suffice in order to estimate the characteristics of soil radon transport. 相似文献
54.
Fayez Ahmad Sherif Farouk Mohamed W. Abd El-Moghny 《Proceedings of the Geologists' Association. Geologists' Association》2014
Facies analyses and a sequence stratigraphical framework with regional correlation of the upper Campanian phosphate province are presented, based on three main sections located in Egypt (Gebel Duwi and Abu Tartur sections) and north Jordan (Umm Qais section). Fifteen facies types were grouped into: phosphate (FT1–5), carbonate (FT6–11) and siliciclastic (FT12–15) facies associations. The main component of phosphate rocks is pellets in situ and common reworked biogenic debris, especially in the upper phosphate beds (e.g. fish teeth and bones), which along with abundant Thalassinoides burrows suggests that the skeletal material was the main source for phosphates in Egypt; in contrast the common authigenic phosphatic grains (pristine) in Jordan reflect an upwelling regime. Based on age assignment as well as stratigraphical position, the phosphorite beds show great similarity that may suggests a similar origin and proximity during the period of deposition of the Duwi Formation of the Red Sea coast of Egypt and its equivalent, the Al-Hisa Phosphorite Formation in Jordan, which represents an early transgressive system tract of a depositional sequence. On the Abu Tartur plateau, the presence of sandy pyritic phosphatic grainstone (FT1) and glauconitic quartz arenite (FT12) in the middle part of the studied section, along with the absence of chert facies (FT14), reflects a more shallow marine depositional environment with increased fluvial sediment supply compared to those along the Red Sea coast and north Jordan. 相似文献
55.
The demand for water resources in the area south of the Dead Sea due to continued development, especially at the Arab Potash
Company (APC) works necessitates that water quality in the area be monitored and evaluated based on the local geology and
hydrogeology. The objective of this paper is to provide information on the past and present status of the main aquifers under
exploitation or planned for future development. Two main aquifers are discussed: the Safi water field, presently being operated,
and the Dhiraa water field, which is being developed. The aquifer developed in the Safi water field is shallow and fed by
the Hasa fault system, which drains a significant portion of the Karak mountains. This aquifer seems to be well replenished
within the core, where no obvious long-term degradation in water quality can be identified. However, in the low recharge areas
within the distal portions of the alluvial fan, there has been a degradation in water quality with time. The degradation is
caused by the dissolution of the Lisan Marl, which is present at the outskirts of the fan system, based on hydrochemistry
of water in the wells. The Dhiraa field is a deep (800–950 m) aquifer drilled specifically for the extraction of brackish
water present in the Kurnub aquifer. Available data indicate that there are at least three distinct water types within this
field. These water types are variable in quality, and there may be potential for mixing of these waters, thus affecting the
quality of the freshest waters presently available. Tritium and oxygen isotope analysis indicate that the water is old and
possibly nonrenewable.
Received: 24 July 1995 · Accepted: 26 September 1995 相似文献
56.
At Wadi Sabra (SW Jordan) human occupation dates back to the Palaeolithic and Epipalaeolithic. Although there is stratigraphic correlation based on archaeological finds of Ahmarian origin, numerical age estimates are lacking. We applied single-aliquot optical dating of coarse grained quartz of wadi deposits and investigated the luminescence properties in detail to achieve more accurate age information about the time of human occupation. Weak luminescence signals and scattered dose distributions characterise the multi-grain aliquots. The residual doses of the investigated modern wadi sediment are between 0 and 7 Gy. Moreover, comparison of equivalent dose (De) values of 1 mm and 8 mm aliquots shows higher equivalent doses for the large aliquots. Both experiments indicate that the luminescence signal is partially bleached prior to deposition. The dose distributions of all samples are broadly scattered and have overdispersion values between 25 and 43%, some samples are significantly skewed. The shape of the dose distributions points to other sources of scatter, in addition to partial bleaching. Comparison of 1 mm multi-grain and single-grain data demonstrates that the luminescence signal of one multi-grain aliquot most likely is from a single grain. For this reason, variation in the number of photon counts due to the weak luminescence intensity and variations in beta microdosimetry have a bigger impact on the spread of dose distributions. However, we cannot quantify the particular impact of partial bleaching, weak luminescence intensity and beta microdosimetry. To account for the spread of the dose distribution, we use the central age model to calculate equivalent doses. Age calculations yield results in the range of 30–48 ka. 相似文献
57.
ABSTRACTThis article analyses the nexus of technocracy–peacebuilding and its implications on water conflicts and hydropolitics. It is a conceptual exploration which advances an interdisciplinary approach by combining theories from two distinct research fields: peacebuilding and transboundary water management. It probes the argument that synergies between water management, development and peacebuilding frequently lead to technocratic and functional solutions. As empirical case illustration, the transboundary project, the Red Sea–Dead Sea Water Conveyance (RSDSWC) is analysed regarding its peacebuilding and peace promoting potential. Three concluding remarks are drawn from the conceptual and empirical analysis. First, strong emphasis on technocratic solutions is inclined to favour supply-oriented options rather than solutions based on ethics of sustainable development and rights-based distribution. Second, functional solutions to water conflicts downplay at times complex hydro-political and asymmetrical relations between adversaries. Third, wider trends of privatization in the water sector coincide with similar developments in the field of peacebuilding, where new transnational actors are gaining influence as “new peacemakers”, which are likely to have long-term consequences on power relations and the resolution of water conflict.
EDITOR D. Koutsoyiannis; ASSOCIATE EDITOR not assigned 相似文献
58.
A water harvesting system for research purposes has been established in the Lisan Peninsula of the Dead Sea in the middle of the Jordan Rift Valley, where no authorized guideline is available for designing water harvesting systems. Rainfall and runoff, which occurred as flash floods, were observed at the downstream end of a gorge with a 1.12 km2 barren catchment area from October 2014 through July 2019. Due to the extremely arid environment, runoff from the catchment is ephemeral, and the flash flood events can be clearly distinguishable from each other. Thirteen flash flood events with a total runoff volume of more than 100 m3 were successfully recorded during the five rainy seasons. Pearson and Spearman correlations between duration, total rainfall depths at two points, total runoff volume, maximum runoff discharge, bulk runoff coefficient, total variation in runoff discharge and maximum variation in runoff discharge of each flash flood event were examined, revealing no straightforward relationship between rainfall and runoff. The performance of the conventional SCS runoff curve number method was also deficient in reproducing any rainfall–runoff relationship. Therefore, probability distribution fitting was performed for each random variable, focusing on the lognormal distribution with three parameters and the generalized extreme value distribution. The maximum goodness-of-fit estimation turns out to be a more rational and efficient method in obtaining the parameter values of those probability distributions rather than the standard maximum likelihood estimation, which has known disadvantages. Results support the design of the water harvesting system and provide quantitative information for designing and operating similar systems in the future. 相似文献
59.
Yehouda Enzel Rivka Amit Uri Dayan Onn Crouvi Ron Kahana Baruch Ziv David Sharon 《Global and Planetary Change》2008,60(3-4):165-192
Modern-day synoptic-scale eastern Mediterranean climatology provides a useful context to synthesize the diverse late Pleistocene (60–12 ka) paleohydrologic and paleoenvironmental indicators of past climatic conditions in the Levant and the deserts to its south and east. We first critically evaluate, extract, and summarize paleoenvironmental and paleohydrologic records. Then, we propose a framework of eastern Mediterranean atmospheric circulation features interacting with the morphology and location of the southeast Mediterranean coast. Together they strongly control the spatial distribution of rainfall and wind pattern. This cyclone–physiography interaction enforces the observed rainfall patterns by hampering rainfall generation south and southeast of the latitude of the north Sinai coast, currently at 31°15′.The proposed framework explains the much-increased rains in Lebanon and northern Israel and Jordan as deduced from pollen, rise and maintenance of Lake Lisan, and speleothem formation in areas currently arid and semiarid. The proposed framework also accounts for the southward and eastward transition into semiarid, arid, and hyperarid deserts as expressed in thick loess accumulation at the deserts' margins, dune migration from west to east in the Sinai and the western Negev, and the formation of hyperarid (< 80 mm yr− 1) gypsic–salic soils in the southern Negev and Sinai. Our climatic synthesis explains the hyperarid condition in the southern Negev, located only 200–250 km south of the much-increased rains in the north, probably reflecting a steeper rainfall gradient than the present-day gradient from the wetter Levant into its bordering southern and eastern deserts.At present, the rainiest winter seasons in Lebanon and northern and central Israel are associated with more frequent (+ 20%), deeper Cyprus Lows traversing the eastern Mediterranean at approximately the latitude of southern Turkey. Even these wettest years in northern Israel do not yield above average annual rainfall amounts in the hyperarid southern Negev. This region is mainly influenced by the Active Red Sea Troughs that produce only localized rains. The eastern Mediterranean Cyprus Lows also produce more dust storms and transport higher amounts of suspended dust to the loess area than any other atmospheric pattern. Concurrent rainfall and dust are essential to the late Pleistocene formation of the elongated thick loess zone along the desert northern margin. Even with existing dust storms, the lack of rain and very sparse vegetation account for the absence of late Pleistocene loess sequences from the southern Negev and the formation of hyperarid soils.When the north Sinai coast shifted 30–70 km northwest due to last glacial global sea level lowering, the newly exposed coastal areas supplied the sand and dust to these active eastern Mediterranean cyclones. This enforced the latitude of the northern boundary of the loess zone to be directly due east of the LGM shoreline. This shift of coast to the northwest inhibited rainfall in the southern Levant deserts and maintained their hyperaridity. Concurrently, frequent deep eastern Mediterranean Cyprus Lows were funneled along the northern Mediterranean increasing (probably doubling) the rains in central and northern Israel, Lebanon, southwestern Syria and northern Jordan. These storms and rains formed lakes, forests, and speleothems only a short distance north of the deserts in the southern Levant. 相似文献
60.