全文获取类型
收费全文 | 130篇 |
免费 | 7篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 5篇 |
大气科学 | 2篇 |
地球物理 | 42篇 |
地质学 | 68篇 |
海洋学 | 7篇 |
天文学 | 9篇 |
自然地理 | 5篇 |
出版年
2022年 | 2篇 |
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 11篇 |
2017年 | 8篇 |
2016年 | 5篇 |
2015年 | 2篇 |
2014年 | 10篇 |
2013年 | 10篇 |
2012年 | 7篇 |
2011年 | 7篇 |
2010年 | 10篇 |
2009年 | 5篇 |
2008年 | 8篇 |
2007年 | 4篇 |
2006年 | 10篇 |
2005年 | 8篇 |
2004年 | 1篇 |
2003年 | 1篇 |
2002年 | 2篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1996年 | 3篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有138条查询结果,搜索用时 343 毫秒
91.
Ali Sungur Mustafa Soylak Selehattin Yilmaz Hasan Özcan 《Environmental Earth Sciences》2014,72(9):3293-3305
Utilizing the sequential extraction procedure (acid soluble, reducible, oxidizable, and residual) proposed by The European Community Bureau of Reference (BCR), the trace metals present in the sediments of the Ergene River, Turkey, were determined. The sediment samples were collected from 10 sampling sites and analyzed to identify the concentrations of cadmium, cobalt, chromium, copper, manganese, nickel, lead and zinc. The flame atomic absorption spectrometer was used for metal determination. The validation of the results was checked by the analysis of the BCR-701 standard reference material. The relationship existing between the sediment characteristics and metal fractions was identified using the correlation analysis. Hierarchical cluster analysis was performed to find out the grouping of the sampling sites based on the similarities of the heavy metals in the bioavailable fraction. When the extractable amounts of heavy metals are considered, the quantity of the mobile fractions (viz., acid soluble, reducible, and oxidizable) of the heavy metals is observed to be higher when compared with that of the immobile fraction (residual). This might be caused by the anthropogenic sources. Besides, it was statistically discovered that the organic matter, pH and clay contents could influence the bonding of the analyte metals in various forms. The cluster analysis revealed three clusters of the sampling stations, with group I (S5-8) and group II (S3, S4 and S9) showing higher environmental risks. The risk assessment code indicated that the highly mobile soluble fractions of Mn, Zn, Cd and Co created a high environmental risk which could result in negative impacts on the aquatic biota. 相似文献
92.
Volkan Bakis Ahmet Erdem Edwin Budding Osman Demircan Hicran Bakis 《Astrophysics and Space Science》2005,296(1-4):131-134
An astrometric solution, together with time of minimum analysis, has been made for the multiple system XY Leonis (HIP 49136)
to identify the properties of the remote companion to the eclipsing pair (AB). From this solution, we derive the inclination
of the wide orbit (AB-cd) as 94.4∘± 0.2∘, angle of nodes as 247.3∘± 0.2∘, and the mass of the wide component (the dwarf binary cd) as 0.98 ± 0.2 M⊙. This study confirms that the light travel time effect can explain the sinusoidal O−C variation of the eclipsing system. 相似文献
93.
S. Selam B. Albayrak M. Yilmaz H. V. Şenavci İ Özavci C. Çetintaş 《Astrophysics and Space Science》2005,296(1-4):305-308
Photoelectric UBV light curves of the recently discovered eclipsing binary HX UMa were obtained and studied to determine the preliminary physical
parameters of the system for the first time. The observations were taken at the TüBİTAK1 – Turkish National Observatory (TUG) on three nights in April 2003. A simultaneous analysis of the light and radial velocity
curves yields a typical A-type contact binary with a high degree of overcontact. The influence of the close visual companion
to the total light of the system was taken into account during the analysis.
1TüBİTAK: The Scientific and Technical Research Council of Turkey. 相似文献
94.
The Earth's water resources are endangered by inconsiderate use, pollution and lack of conservation measures. Temporal monitoring is necessary for the conservation and usage planning of water resources and to make informed decisions. Seyfe Lake and its environs in Turkey is one of the most important water basins in the world, because it is a node on bird migration paths between Europe, Asia and Africa. For this reason, the International Council of Bird Preservation (ICBP) has registered 27 of the bird species living at Seyfe Lake on the conservation list. In this work, the temporal changes in the water surface area of Seyfe Lake and its environs, which are important for ecological, historical and tourism reasons, are investigated. The change of water surface in the lake is examined over a 26 year period using satellite images taken between 1975 and 2001. Landsat images from years 1975, 1987 and 2001 are used. The change is tracked from the images using an unsupervised classification method. A decrease of slightly more than 33% was observed in the water surface area this 26 year period. The temporal change indicated by the images was compared with the related meteorological data between 1975 and 2001. Over this time period, climate conditions (rainfall, temperature and evaporation) in the study area have been changed by approximately 21%. These changes could have affected the Lake surface area, but so also could external human interference around the Lake. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
95.
96.
Assuming a perfect fluid distribution of matter Bianchi type Vspace-time is considered and using a new generation techniqueit is shown that the field equations are solvable for anyarbitrary cosmic scale function. Solutions for particularforms of cosmic scale functions are obtained, and thegeometrical and physical properties of these solutions discussed. 相似文献
97.
The present study reports the synthesis of a novel ionophore, calix[4]azacrown ( 5 ) bearing two amino groups at the lower rim along with its oligomeric analogue ( 6 ). The liquid‐liquid extraction properties of these compounds towards selected metal cations and dichromate anions have been evaluated. It is observed that ( 5 ) and ( 6 ) are good extractants for the selected metal cations. However, in the case of dichromate anion, only species ( 5 ) shows remarkable extraction properties at low pH, whereas species ( 6 ) shows poor extraction behavior. The results have importance especially in wastewater treatment to obtain environmentally safe industrial effluent and they should also assist supramolecular chemists in designing and synthesizing more sophisticated host molecules for the removal of toxic pollutants. 相似文献
98.
Structural and geomorphological aspects of the Kat landslides (Tokat—Turkey) and susceptibility mapping by means of GIS 总被引:3,自引:0,他引:3
Kat County, which is located in a slope of hilly region and constructed in the side of a mountain along the North Anatolian Fault Zone, is frequently subject to landslides. The slides occur during periods of heavy rainfall, and these events cause destruction to property, roads, agricultural lands and buildings. In the last few decades, a lot of houses and buildings have been damaged and destroyed. Settlement areas have remained evacuated for a long time. The slope instabilities in the study area are a complex landslide extending from north to south containing a lot of landslides. Field investigations, interpretation of aerial photography, analyses of geological data and laboratory tests suggest that some factors have acted together on the slopes to cause the sliding. In the wet season, the slopes became saturated. As the saturation of the earth material on the slope causesa rise in water pressure, the shear strength (resisting forces) decreases and the weight (driving forces) increases; thus, the net effect was to lower the safety factor. Previous failures have affected the rock mass, leading to the presence of already sheared surfaces at residual strengths. The relation between the joint planes and the instability of the slope in the study area was discussed and it was found that the potential slope instabilities are mainly in the directions of NW–SE, NE–SW and N–S. The landslide susceptibility map obtained by using the geographical information system showed that a large area is susceptible and prone to landslides in the northern part of the study area.An erratum to this article can be found at 相似文献
99.
Soil liquefaction susceptibility and hazard mapping in the residential area of Kütahya (Turkey) 总被引:2,自引:0,他引:2
This study presents the results of both field and laboratory tests that have been undertaken to assess liquefaction susceptibilities
of the soils in Kütahya city, located in the well-known seismically active fault zone. Liquefaction potentials of the sub-surface
materials at Kütahya city were estimated by using the geological aspect and geotechnical methods such as SPT method of field
testing. And, the data obtained have been mapped according to susceptibility and hazard. The susceptibility map indicated
“liquefable” and “marginally liquefable” areas in alluvium, and “non-liquefable” areas in Neogene unit for the magnitude of
earthquake of M=6.5; whereas, liquefaction hazard map produced by using of liquefaction potential index showed the severity categories from
“very low” to “high.” However, a large area in the study area is prone to liquefy according to liquefaction susceptibility
map; the large parts of the liquefable horizon are mapped as “low” class of severity by the use of the liquefaction potential
index. It can be said that hazard mapping of liquefaction for a given site is crucial than producing liquefaction susceptibility
map for estimating the severity. Both the susceptibility and hazard maps should be produced and correlated with each other
for planning in an engineering point of view. 相似文献
100.
Texture and grain size is of great importance in understanding the mechanical properties of rocks. The aim of this study was to investigate textural and slaking durability characteristics, and correlate them with the gypsum types where the dolines occurred, with particular reference to the texture and crystal size. The investigation comprised two stages: field work and laboratory testing. Initially, rock samples were obtained from various representative karstified and non-karstified locations. Thereafter, mineralogical, physical and slaking durability characteristics of the gypsum samples were determined by means of laboratory testing. After the field and laboratory works, the geological, mineralogical and slaking durability characteristics of the study area gypsum were reviewed and discussed from the point of view of doline formation. Results showed that fine grain sized alabastrine gypsum tends to be karstified and leads to doline formation. This is closely related to the crystal size, texture and attributable to the slaking durability of the gypsum. Consequently, the results demonstrate that the texture, especially crystal size, and effective porosity are important parameters controlling the slake durability of the gypsum and doline formation. 相似文献