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91.
Rainfall network design using kriging and entropy 总被引:4,自引:0,他引:4
The spatial distribution of rainfall is related to meteorological and topographical factors. An understanding of the weather and topography is required to select the locations of the rain gauge stations in the catchment to obtain the optimum information. In theory, a well‐designed rainfall network can accurately represent and provide the needed information of rainfall in the catchment. However, the available rainfall data are rarely adequate in the mountainous area of Taiwan. In order to provide enough rainfall data to assure the success of water projects, the rainfall network based on the existing rain gauge stations has to be redesigned. A method composed of kriging and entropy that can determine the optimum number and spatial distribution of rain gauge stations in catchments is proposed. Kriging as an interpolator, which performs linear averaging to reconstruct the rainfall over the catchment on the basis of the observed rainfall, is used to compute the spatial variations of rainfall. Thus, the rainfall data at the locations of the candidate rain gauge stations can be reconstructed. The information entropy reveals the rainfall information of the each rain gauge station in the catchment. By calculating the joint entropy and the transmitted information, the candidate rain gauge stations are prioritized. In addition, the saturation of rainfall information can be used to add or remove the rain gauge stations. Thus, the optimum spatial distribution and the minimum number of rain gauge stations in the network can be determined. The catchment of the Shimen Reservoir in Taiwan is used to illustrate the method. The result shows that only seven rain gauge stations are needed to provide the necessary information. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
92.
Summary The possibility of climate change in the Korean Peninsula has been examined in view of the general increase in greenhouse
gases. Analyses include changes in annual temperature and precipitation. These analyses are supplemented with our observations
regarding the apparent decrease of forest areas.
It was found that there was a 0.96 °C (0.42 °C per decade) increase in annual mean temperature between 1974 and 1997. The
increase in large cities was 1.5 °C but only 0.58 °C at rural and marine stations. The difference in the mean temperature
between large cities and rural stations was small from 1974 to 1981. However, the difference increased from 1982 to 1997.
In particular, the warming appears most significant in winter. Prior to 1982, the lowest temperatures were often −18 °C in
central Korea, and since then the lowest temperatures have been only −12∼−14 °C. Recently, the minimum January temperature
has increased at a rate of 1.5 °C per decade. It is estimated that the increase of1 °C in annual mean temperature corresponds
to about a 250 km northward shift of the subtropical zone boundary.
The analysis of data from 1906 to 1997 indicates a trend of increasing annual precipitation, an increase of 182 mm during
the 92-year peirod, with large year-to-year variations. More than half of the annual mean amount, 1,274 mm, occurred from
June to September.
Meteorological data and satellite observations suggest that changes have occurred in the characteristics of the quasi-stationary
fronts that produce summer rain. In recent years scattered local heavy showers usually occur with an inactive showery front,
in comparison with the classical steady rain for more than three weeks. For instance, local heavy rainfall, on 6 August 1998
was in the range of 123–481 mm. The scattered convective storms resulted in flooding with a heavy toll of approx. 500 people.
The northward shift of the inactive showery front over Korea, and of a convergence zone in central China, correlate with the
increase in temperature. It has been suggested that the decrease in forest areas and the change in ground cover also contribute
to the warming of the Korean Peninsula.
Received March 16, 2000 相似文献
93.
The discrete element method (DEM) is used to study the response of anisotropic rocks under true triaxial testing. Numerical samples of seven different bedding orientations (β = 0o, 15o, 30o, 45o, 60o, 75o, and 90o) are created. Six series of test simulations (σ3 = 0, 10, 30, 50, 70, and 100 MPa) are conducted on each sample, with five different σ2 values, varied from σ3 to σ1. The effects of anisotropy and intermediate stress on the peak strength, brittle-ductile transition, and degree of anisotropy are subsequently explained through underlying micromechanics. Results show a “fan-shaped” variation of the peak strength with σ2, displaying an ascending-then-descending trend. An increasing brittleness with σ2 is observed at lower confining pressures for all, but medium anisotropy angles. For higher confining pressures, increasing ductility with σ2 is seen for every anisotropy angle. A U-shaped variation of peak strength with anisotropy angles is noted that flattens under high intermediate stress. Hence, for numerical models of Posidonia shale under normalized σ2 higher than 0.76, the anisotropy effect is found to be negligible. Micromechanical analyses reveal that the stress asymmetry, suppression of weak plane action as well as the localization and coalescence of microcracks in the intact rock matrix, due to σ2, are the contributors towards the obtained trends. Since existing failure criteria do not weigh in these features in geotechnical assessments, this paper helps future studies by providing a deeper understanding of these effects and a comprehensive data set for the analyses of anisotropic rocks under polyaxial stress conditions. 相似文献
94.
Cambrian siliciclastic sequences along the Dead Sea Transform (DST) margin in southern Israel and southern Jordan host both detrital fluorapatite [D‐apatite] and U‐rich authigenic carbonate‐fluorapatite (francolite) [A‐apatite]. D‐apatite and underlying Neoproterozoic basement apatite yield fission‐track (FT) data reflecting Palaeozoic–Mesozoic sedimentary cycles and epeirogenic events, and dispersed (U–Th–Sm)/He (AHe) ages. A‐apatite, which may partially or completely replace D‐apatite, yields an early Miocene FT age suggesting formation by fracturing, hydrothermal fluid ascent and intra‐strata recrystallisation, linked to early DST motion. The DST, separating the African and Arabian plates, records ~105 km of sinistral strike‐slip displacement, but became more transtensional post‐5 Ma. Helium diffusion measurements on A‐apatite are consistent with thermally activated volume diffusion, indicating Tc ~52 to 56 ± 10°C (cooling rate 10°C/Ma). A‐apatite AHe data record Pliocene cooling (~35 to 40°C) during the transtensional phase of movement. This suggests that timing of important milestones in DST motion can be discerned using A‐apatite low‐temperature thermochronology data alone. 相似文献
95.
Long-term discharge of turbid water from reservoirs after flood events is a major socioenvironmental problem in many countries, including Korea. This study used a suite of mathematical models to simulate the fate of turbidity flows in the Soyanggang Reservoir in Korea, an important source of drinking water for the Seoul Capital Area, in response to extreme floods based on the Representative Concentration Pathway 4.5 climate scenario. It evaluated the effectiveness of the selective withdrawal facility (SWF), installed recently in the Soyanggang Reservoir to control persistent turbidity. Extreme floods with a maximum daily inflow rate greater than the historical maximum observed in 2006 were projected to occur four times in this century. The fate and transport of turbidity flows were highly influenced by both the thermal stability of the reservoir and the season in which the flood event occurred. Thus, SWF operations should consider the timing of extreme events (i.e., the imminence of the autumn turnover) to mitigate the impact of high turbidity on the water supply and downstream ecosystem. It was found to be ineffective under extreme events if these occurred in two consecutive years. Current reservoir operations, which rely heavily on the SWF, are likely to be inadequate to overcome the negative effects of extreme-turbidity events on reliably providing safe water supplies. Coping with the worst event expected to occur in the future would require additional countermeasures such as bypassing high-turbidity water. 相似文献
96.
Chung Huang Yu-Chang Chan Jyr-Ching Hu Jacques Angelier Jian-Cheng Lee 《Journal of Structural Geology》2008,30(9):1167-1176
The northern segment of the Chelungpu Fault shows an unusually large co-seismic displacement from the event of the Mw 7.6 Chi-Chi earthquake in western Taiwan. Part of the northern segment near the Fengyuan City provides an excellent opportunity for characterizing active thrust-related structures due to a dense geodetic-benchmark network. We reproduced co-seismic deformation patterns of a small segment of this Chelungpu Fault using 924 geodetic benchmarks. According to the estimated displacement vectors, we identified secondary deformations, such as local rigid-block rotation and significant shortening within the hanging wall. The data set also allows us to determine accurately a 3D model of the thrust fault geometry in the shallow subsurface by assuming simple relations between the fault slip, and the horizontal and vertical displacements at the surface. The predicted thrust geometry is in good agreement with borehole data derived from two drilling sites close to the study area. The successful prediction supports our assumptions of rigid displacement and control of displacement in the hanging wall by the fault geometry being useful first approximations. 相似文献
97.
98.
Uran Chung Jin-Hee Kim Kwang-Hyung Kim 《Asia-Pacific Journal of Atmospheric Sciences》2016,52(5):509-518
In this study, we analyzed changes in the predicted flowering date (PFD) for cherry blossom trees under changing climate conditions by simulating the PFDs for six sites on the Korean Peninsula between 1981 and 2010. The spatial downscaled climate data from the Representative Concentration Pathways (RCP) 8.5 scenarios of 30 global climate models (GCMs) were used in the analysis. Here, we present the range of uncertainty in the PFDs, which were calculated by comparing the simulated PFDs to the observed flowering dates. We determined that the root-mean-square errors (RMSEs) of PFDs from individual GCMs, at 7-15 days, were greater in range than those of the mean PFDs from multiple GCMs, at 7-8 days. During three future periods of 2011-2040, 2041-2070, and 2071-2100, the standard deviations (SD), the interquartile ranges (IQRs), and the relative changes in the mean predicted flowering dates (MPFDs) were calculated to quantify the uncertainty levels inherent from the climate scenarios of multiple GCMs. Distinctive changes in the SDs and IQRs of MPFD were found among the analyzed sites. The SDs increased with time between each future period in Seoul, Incheon, and Jeonju, whereas those in Daegu, Busan, and Mokpo decreased with time. In addition, the IQRs increased with time at Seoul, Incheon, Jeonju, and Daegu but not at Busan and Mokpo. The relative changes in the MPFDs at all six sites became greater with time toward the year 2100. Therefore, combining multiple GCM scenarios may not contribute largely to reduce the uncertainty in the PFDs under changing climate conditions, although it may be useful in quantifying the uncertainty in order to make better decisions based on more accurate information. 相似文献
99.
Gyung Soo Park Sang Hee Lee Soung Yun Park Seong Jin Yoon Seung Min Lee Chang Soo Chung Gi -Hoon Hong Suk Hyun Kim 《Ocean Science Journal》2005,40(2):91-100
Bioassay using the marine bacteria,Vibrio fischeri and rotifer,Brachionus plicatilis, and chemical analyses were conducted to assess the toxicity of the various sewage sludges, one of the major ocean dumped materials in the Yellow Sea of Korea. Sludge elutriates extracted by filtered seawater were used to estimate the ecotoxicity of the sludge. Chemical characterization included the analyses of organic contents, heavy metals, and persistent organic pollutants in sludge. Bacterial bioluminescent inhibition (15 min), rotifer mortality (24 hr) and rotifer population growth inhibition (48 hr) assay were conducted to estimate the sludge toxicity. EC50 15 min (inhibition concentration of bioluminescence after 15 minutes exposed) values by Microtox® bioassay clearly revealed different toxicity levels depending on the sludge sources. Highest toxicity for the bacteria was found with the sludge extract from dyeing waste and followed by industrial waste, livestock waste, and leather processing waste. Clear toxic effects on the bacteria were not found in the sludge extract from filtration bed sludge and rural sewage sludge. Consistent with Microtox® results, rotifer neonate mortality and population growth inhibition test also showed highest toxicity in dyeing waste and low in filtration bed and rural sewage sludge. High concentrations of persistent organic pollutants (POPs) and heavy metals were measured in the samples from the industrial wastes, leather processing plant waste sludge, and urban sewage sludge. However, there was no significant correlation between pollutant concentration levels and the toxicity values of the sludge. This suggests that the ecotoxicity in addition to the chemical analyses of various sludge samples must be estimated before release of potential harmful waste in the natural environment as part of an ecological risk assessment. 相似文献
100.
The Neo‐Tethyan subduction that operated before the India‐Asia collision resulted in an Andean‐type convergent margin in South Asia and was associated with extensive arc magmatism that formed the Transhimalayan batholiths. Magmatism in the Gangdese Batholith, the largest batholith exposed in the Lhasa terrane of southern Tibet, is considered to have lasted from the early Jurassic to Eocene. However, eastward correlation of the Gangdese Batholith is uncertain because it is truncated by the eastern Himalayan syntaxis. Here, we report new data from the Lohit Batholith, NE India, including: (i) zircon U‐Pb ages of five granitoids from ca. 148 to 96 Ma; and (ii) zircon Hf isotopes of these rocks that yield high and positive εHf(T) values. We argue that the Lohit Batholith is the eastward extension of the Gangdese Batholith, and can be correlated southward to the Wuntho‐Popa arc in West Burma, thus linking a prolonged Neo‐Tethyan magmatic arc system from southern Tibet to Southeast Asia. 相似文献