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排序方式: 共有378条查询结果,搜索用时 15 毫秒
111.
This paper describes the application and calculation of hydrocarbon anomalies in two different boreholes located in Eastern Pomerania (northern Poland). Spectrometric data from borehole geophysical probe (borehole 1) and portable gamma logger (borehole 2) were used to analyze shale formations. The results from borehole 1 presented a statistically significant, moderate correlation between calculated hydrocarbon anomalies and hydrocarbon saturation data obtained from well log interpretation. Borehole 2 has been analyzed focusing on the gamma radiation of the core samples, and the positive results of borehole 1. Hydrocarbon anomalies calculated from spectral gamma radiation are reliable indicators of sweet spots, based solely on a cursory evaluation of core measurements. These preliminary information acquired from gamma-ray measurements could help increase sampling precision of further geochemical analysis. 相似文献
112.
González Juan González Gabriel Aránguiz Rafael Melgar Diego Zamora Natalia Shrivastava Mahesh N. Das Ranjit Catalán Patricio A. Cienfuegos Rodrigo 《Natural Hazards》2020,101(1):231-253
Natural Hazards - This paper presents an investigation of the collapse of a 325-year-old multi-tiered heritage temple during the 2015 Gorkha earthquake in Kathmandu, Nepal. The research comprises a... 相似文献
113.
Correa Oscar García Francisco Bernal Gabriel Cardona Omar Darío Rodriguez Carlos 《Natural Hazards》2020,100(1):345-361
Natural Hazards - A methodology to define rainfall-landslide thresholds, using a probabilistic model in which the accumulated rainfall at any time is treated as a random variable, is proposed. The... 相似文献
114.
Diana Zúñiga M. Mar Flexas Anna Sanchez-Vidal Johan Coenjaerts Antoni Calafat Gabriel Jordà Jordi García-Orellana Joan Puigdefàbregas Miquel Canals Manuel Espino Francesc Sardà Joan B. Company 《Progress in Oceanography》2009,82(4):239-251
Within the framework of the multidisciplinary RECS project and with the aim of describing the particle flux transfer from the continental shelf to the deep basin, an array of five mooring lines equipped with a total of five pairs of PPS3/3 sequential-sampling sediment traps and RCM-7/8 current meters were deployed 30 m above the bottom from March 2003 to March 2004 inside and outside the Blanes Canyon. One mooring line was located in the upper canyon at 600 m depth, one in the canyon axis at 1700 m depth and other two close to the canyon walls at 900 m depth. A fifth mooring line was deployed in the continental open slope at 1500 m water depth.The highest near-bottom downward particle flux (14.50 g m−2 d−1) was recorded at the trap located in the upper canyon (M1), where continental inputs associated with the presence of the Tordera River are most relevant. On the other hand, the downward fluxes (4.35 g m−2 d−1) in the canyon axis (M2) were of the same order as those found in the western flank (M3) of the canyon. Both values were clearly higher than the value (1.95 g m−2 d−1) recorded at the eastern canyon wall (M4). The open slope (M5) mass flux (5.42 mg m−2 d−1) recorded by the sediment trap located outside the canyon system was three orders of magnitude lower than the other values registered by the inner canyon stations. The relevance of our data is that it explains how the transport pathway in the canyon occurs through its western flank, where a more active and persistent current toward the open ocean was recorded over the entire year of the experiment.Off-shelf sediment transport along the canyon axis showed clear differences during the period of the study, with some important events leading to strong intensifications of the current coupled with large transport of particle fluxes to the deepest parts of the canyon. Such events are primarily related to increases in river discharge and the occurrence of strong storms and cascading events during the winter.In summary, in this study it is shown that the dynamics of the water masses and the currents in the study area convert the sharp western flank of the Blanes Canyon in a more active region that favors erosion processes than the eastern flank, which has a smoother topography and where the absence of erosional conditions yields to steadier sedimentary processes. 相似文献
115.
Araceli Zamora-Camacho Juan Manuel Espíndola Gabriel Reyes-Dávila 《Pure and Applied Geophysics》2007,164(1):39-52
Volcán de Colima, the most active volcano in Mexico, had a climactic episode on 20 November, 1998. On this date, a dome formed
on the small summit crater during the previous few days, collapsed generating block-and-ash flows. The event was preceded
by almost twelve months of seismic activity, which continued afterwards for several more months. We analyzed the main seismic
activity, which occurred from 20 March, 1998 to 31 March, 1999. The seismicity was dominated by volcano-tectonic earthquakes
before the climax, and subsequently by hybrid and long-period earthquakes. We determined the frequency of events for the entire
period, and located most of the volcano-tectonic events. To assess the possibility that these earthquakes were generated by
the same source, they were tested for their similitude through cross correlation in the time domain. Six groups of similar
events, or earthquake families, were generated. The members of these families appeared before the 20 November event, apparently
ceasing afterwards. We examined the location of the families' events with respect to an existing gravity model in which an
anomalous body of negative density contrast suggests the presence of the magma chamber. Most of the family events occur on
top of the anomalous body, which suggests they were associated with the passage of magma through the feeding conduits of the
volcano. 相似文献
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118.
This work was focused on the assessment of changes occurring in crop production and climate during the 20th century in Argentina.
The study was carried out for nine sites located in the Pampas region that are representative of contrasting environments.
We have considered the four main crops cultivated in this area (wheat, maize, sunflower and soybean). Historical climatic
data and crop production related variables (yield, planted area, harvested area) were analyzed and, by means of crop simulation
models, we quantified the impact of climate on crop yields. Changes occurring in climate during the three last decades of
the 20th century were characterized by important increases in precipitation especially between October and March, decreases
in maximum temperature and solar radiation in particular during spring and summer and increases in minimum temperature during
almost all of the year. These changes contributed to increases in yields, especially in summer crops and in the semiarid zone,
mostly due to increases in precipitation, although changes in temperature and radiation also affected crop yields but to a
lesser extent. Comparing the period 1950–1970 with 1971–1999, yields increases attributable to changes in climate were 38%
in soybean, 18% in maize, 13% in wheat, and 12% in sunflower while mean observed yield increases were 110% for maize, 56%
for wheat and 102% for sunflower. 相似文献
119.
120.
Reliable information on water use and availability at basin and field scales are important to ensure the optimized constructive uses of available water resources. This study was conducted with the specific objective to estimate Landsat-based actual evapotranspiration (ETa) using the Operational Simplified Surface Energy Balance (SSEBop) model across the state of South Dakota (SD), USA for the 1986–2018 (33-year) period. Validated ETa estimations (r2 = 0.91, PBIAS = −4%, and %RMSE = 11.8%) were further used to understand the crop water-use characteristics and existing historic mono-directional (increasing/decreasing) trends over the eastern (ESD) and western (WSD) regions of SD. The crop water-use characteristics indicated that the annual cropland water uses across the ESD and WSD were more or less met by the precipitation amounts in the area. The ample water supply and distribution have led to high rainfed and low percentage of irrigated cropland (~2.5%) in the state. The WSD faced greater crop-water use reductions than the ESD during drought periods. The landscape ETa responses across the state were found to be more sensitive than precipitation for the drought impact assessments. The Mann Kendall trend analysis revealed the absence of a significant trend (p > 0.05) in annual ETa at a regional scale due to the varying weather conditions in the state. However, about 12% and 9% cropland areas in the ESD and WSD, respectively, revealed a significant mono-directional trend at pixel scale ETa. Most of the pixels under significant trend showed an increasing trend that can be explained by the shift in agricultural practices, increased irrigated cropland area, higher productions, moisture regime shifts, and decreased risk of farming in the dry areas. The decreasing trend pixels were clustered in mid-eastern SD and could be the result of dynamic conversion of wetlands to croplands and decreased irrigation practices in the region. This study also demonstrates the tremendous potential and robustness of the SSEBop model, Landsat imagery, and remote sensing-based ETa modelling approaches in estimating consistent spatially distributed evapotranspiration. 相似文献