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151.
In this study, we create and critically analyse an automated decision tree classification approach for regional level land cover mapping in insular South-East Asian conditions, using a combination of 10–30 m resolution optical and radar data. The resulting map contains 11 land cover classes and reveals a great deal of contextual information due to high spatial resolution. A limited accuracy assessment indicates 59–97% class wise accuracies. The unprecedented spatial detail of closed canopy oil palm mapping (with user’s accuracy of 90%) is seen as the most promising feature of the mapping approach. The incapability of separating primary forests from other tree cover, and the large variety of different landscapes (e.g. home gardens and tea plantations) classified as shrubland, are considered the main areas for future improvement. Overall, the study demonstrates the great potential of multi-source 10–30 m resolution high data volume land cover mapping approaches in insular South-East Asian conditions. 相似文献
152.
Su Young Lee Yeong Bae Seong Lewis A. Owen Madhav K. Murari Hyoun Soo Lim Ho Il Yoon Kyu‐Cheul Yoo 《Boreas: An International Journal of Quaternary Research》2014,43(1):67-89
The late Quaternary glacial history of the Nun‐Kun massif, located on the boundary between the Greater Himalaya and the Zanskar range in northwestern India, was reconstructed. On the basis of morphostratigraphy and 10Be dating of glacial landforms (moraines and glacial trimlines), five glacial stages were recognized and defined, namely: (i) the Achambur glacial stage dated to Marine Oxygen Isotope Stage 3 to 4 (38.7–62.7 ka); (ii) the Tongul glacial stage dated to the early part of the Lateglacial (16.7–17.4 ka); (iii) the Amantick glacial stage dated to the later part of the Lateglacial (14.3 ka, 11.7–12.4 ka); (iv) the Lomp glacial stage dated to the Little Ice Age; and (v) the Tanak glacial stage, which has the youngest moraines, probably dating to the last few decades or so. Present and former equilibrium‐line altitudes (ELAs) were calculated using the standard area accumulation ratio method. The average present‐day ELA of ~4790 m above sea level in the Greater Himalaya is lower than those in the Ladakh and Zanskar ranges, namely 5380 and ~5900 m a.s.l., respectively. The ELA in the Zanskar range is higher than in the Ladakh range, possibly due to the higher peaks in the Ladakh range that are able to more effectively capture and store snow and ice. ELA depressions decrease towards the Ladakh range (i.e. inner Plateau). Peat beds interbedded with aeolian deposits that cap the terminal moraine of Tarangoz Glacier suggest millennial‐time‐scale climate change throughout the Holocene, with soil formation times at c. 1.5, c. 3.4 and c. 5.2 ka, probably coinciding with Holocene abrupt climate change events. Given the style and timing of glaciation in the study area, it is likely that climate in the Nun‐Kun region is linked to Northern Hemisphere climate oscillations with teleconnections via the mid‐latitude westerlies. 相似文献
153.
Constant slip rate during the late Quaternary along the Sulu He segment of the Altyn Tagh Fault near Changma,Gansu, China 总被引:1,自引:0,他引:1
The question of whether millennial‐scale geological slip rates are consistent with decade‐scale geodetic slip rates is of great importance in evaluating the nature of continental deformation within the Tibetan Plateau. We determined the time‐averaged slip rate of the Sulu He segment of the Altyn Tagh Fault, near Changma in Gansu Province, China, based on geomorphic analysis, remote sensing data, and cosmogenic 10Be surface‐exposure age dating. Quaternary alluvial fan deposits in the study area (Qf1, Qf2, Qf3) are displaced by left‐lateral movement along the Altyn Tagh Fault. Because of the large accumulated displacement of these fans, some of them have become disconnected from the fan apexes that are directly linked to the debris‐source areas in the piedmont of the Qilian Shan to the south. The total minimum offsets are estimated to be about 429 ± 41 m for Qf1, about 130 ± 10 m for Qf2, and 32 ± 1 m for Qf3. The 10Be surface‐exposure ages obtained for Qf1 and Qf2 are 100–112 ka and 31–43 ka, respectively. Accordingly, the slip rate since the period of Qf1 and Qf2 depositions is calculated to have been about 3.7 mm/yr. 相似文献
154.
Dynamic characteristics of monthly rainfall in the Korean Peninsula under climate change 总被引:3,自引:1,他引:2
Min Soo Kyoung Hung Soo Kim Bellie Sivakumar Vijay P. Singh Kyung Soo Ahn 《Stochastic Environmental Research and Risk Assessment (SERRA)》2011,25(4):613-625
Global climate change is one of the most serious issues we are facing today. While its exact impacts on our water resources
are hard to predict, there is a general consensus among scientists that it will result in more frequent and more severe hydrologic
extremes (e.g. floods, droughts). Since rainfall is the primary input for hydrologic and water resource studies, assessment
of the effects of climate change on rainfall is essential for devising proper short-term emergency measures as well as long-term
management strategies. This is particularly the case for a region like the Korean Peninsula, which is susceptible to both
floods (because of its mountainous terrain and frequent intense rainfalls during the short rainy season) and droughts (because
of its smaller area, long non-rainy season, and lack of storage facilities). In view of this, an attempt is made in the present
study to investigate the potential impacts of climate change on rainfall in the Korean Peninsula. More specifically, the dynamics
of ‘present rainfall’ and ‘future rainfall’ at the Seoul meteorological station in the Han River basin are examined and compared;
monthly scale is considered in both cases. As for ‘present rainfall,’ two different data sets are used: (1) observed rainfall
for the period 1971–1999; and (2) rainfall for the period 1951–1999 obtained through downscaling of coarse-scale climate outputs
produced by the Bjerknes Center for Climate Research-Bergen Climate Model Version 2 (BCCR-BCM2.0) climate model with the Intergovernmental
Panel on Climate Change Special Report on Emission Scenarios (IPCC SRES) 20th Century Climate in Coupled Models (20C3M) scenario.
The ‘future rainfall’ (2000–2099) is obtained through downscaling of climate outputs projected by the BCCR-BCM2.0 with the
A2 emission scenario. For downscaling of coarse-scale climate outputs to basin-scale rainfall, a K-nearest neighbor (K-NN) technique is used. Examination of the nature of rainfall dynamics is made through application of four methods: autocorrelation
function, phase space reconstruction, correlation dimension, and close returns plot. The results are somewhat mixed, depending
upon the method, as to whether the rainfall dynamics are chaotic or stochastic; however, the dynamics of the future rainfall
seem more on the chaotic side than on the stochastic side, and more so when compared to that of the present rainfall. 相似文献
155.
Woo-Jin Shin Jong-Sik Ryu Kwang-Sik Lee Gong Soo Chung 《Environmental Earth Sciences》2013,68(8):2271-2279
Seasonal and spatial variations in water chemistry and contaminant sources were investigated in six major rivers in South Korea that vary widely in drainage area and length. The dissolved-load content of the rivers varied seasonally, and some dissolved ions such as Cl? and NO3 ? showed large spatial differences in all of the rivers. The water type changed from Ca–HCO3 in the upper reaches to Na–Cl–NO3 in the lower reaches, indicating anthropogenic contamination in the lower reaches. Compared with two relatively pristine rivers (the Sumjin and Mankyung rivers), the other four rivers, which flow through agricultural and urban areas, registered much higher Cl? and NO3 ? concentrations. Statistical analysis showed that seasonal and spatial variations in water chemistry occurred in all the rivers. The nitrogen and oxygen isotopes of dissolved nitrate indicated that the rivers flowing through urban and agricultural areas were significantly affected by manure, sewage, or both. 相似文献
156.
ABSTRACTA two-parameter monthly water balance model to simulate runoff can be used for a water resources planning programme and climate impact studies. However, the model estimates two parameters of transformation of time scale (c) and of the field capacity (SC) by a trial-and-error method. This study suggests a modified methodology to estimate the parameters c and SC using the meteorological and geological conditions. The modified model is compared with the Kajiyama formula to simulate the runoff in the Han River and International Hydrological Programme representative basins in South Korea. We show that the estimated c and SC can be used as the initial or optimal values for the monthly runoff simulation study in the model.
EDITOR M.C. Acreman; ASSOCIATE EDITOR S. Kanae 相似文献
157.
Khaled K. Al-Taha Richard T. Snodgrass Michael D. Soo 《International journal of geographical information science》2013,27(1):95-103
Abstract There now exist several microcomputer processing systems which incorporate algorithms and display techniques appropriate for the class of objects known as images. Zooming, histogram equalization, contrast stretching, ratioing, edge enhancement, and filtering are common options used in these systems. In the present discussion a system is proposed for the equivalent processing of general resolution elements (resells), instead of the homogeneous picture elements (pixels) which are found in image processing systems. The resel processing system requires a new, generalized, repertoire of processing algorithms and a high resolution display. A summary is provided of the facilities and procedures required, a computational metaphor using computer spreadsheets is described, and the applicability to censels (census data elements) and to medical data is suggested. 相似文献
158.
Underestimation of roughness in rough rock joints 总被引:1,自引:0,他引:1
Numerous studies have been made to improve Barton's shear strength model for the quantification of rock joints. However, in these previous studies, the roughness and shear strength of the rock joint have been underestimated especially for relatively high undulated profiles (joint roughness coefficient (JRC) >14). The main factors of roughness underestimation in rough rock joints are investigated for the proper quantification of rock joint roughness. The aliasing effect and the roughness characteristics are analyzed by using artificial joint profiles and natural rock joint profiles. A 3D camera scanner is adopted to verify the main source of underestimation when using conventional measurement methods. Shear strength tests are carried out by using two types of shear apparatus to study the roughness mobilization characteristics, which may also affect the roughness underestimation. The results of joint roughness assessment, such as aliasing and undulation of waviness, show that the roughness can be underestimated in relatively rough joint profiles (JRC>14). At least two components of roughness parameters are needed to properly represent the joint roughness, for example, the amplitude and the inclination angle of joint asperity. Roughness mobilization is affected by both the normal stress and the asperity scale. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
159.
In this study, a three‐dimensional (3D) non‐hydrostatic circulation model was applied to study the thermal structure, its evolution and water circulation of Yachiyo Lake in Hiroshima, Japan. The simulations were conducted for 1 month during July 2006. The meteorological forcing variables such as wind stress, surface atmospheric pressure and heat flux transfer through the lake surface were provided by an atmospheric mesoscale model run. The vertical mixing process of the lake was calculated using the Mellor‐Yamada turbulence model. The 1‐month numerical simulation revealed the wind‐induced currents of the lake, two gyres in the mid‐layer, and depth‐averaged monthly mean currents. Further numerical experiments studying the mechanism of the two gyres in the lake showed the important role of topography in gyre formation. The thermal structure of the lake and its evolution both in space and in time as predicted by the model showed very good agreement with the observed values and characteristics of Yachiyo Lake. The internal gravity waves, which are crucial for mixing in the stratified lake, are depicted by the vertical fluctuation of isotherms. Using the non‐dimensional gradient Richardson number, Yachiyo Lake was determined to be stable under strong stratification during the study period, and therefore very sensitive to wind stress. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
160.
Ocean Science Journal - Clove oil (CO) is an effective anesthetic. Many hatcheries and research studies use clove oil to immobilize fish for artificial reproduction and surgery to suppress their... 相似文献