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In this paper, we idealize the actual solar atmosphere as a multi-isothermal-layer system so as to obtain the energy transmittance of the linear Alfvén wave that propagates through such a system in presence of a uniform oblique magnetic filed. The results indicate that the two-layer model is essentially different to the three-layer one. In the two-layer model, the temperature jump acts as a high pass filter. In the three-layer model, resonant transfer will take place and the transmittance undergoes oscillation as the trigonometric function terms dominate its behavior. For actual solar atmosphere, the result reveals that the lower parts of solar atmosphere are more suitable for those Alfvén waves with period of seconds to transfer their energy. 相似文献
34.
本文研究了直接测定海洋河弧菌 (vibrio fluvailis) 5 10脂多糖的分光光度法。利用 1,9-二甲基亚甲蓝 (DMB) ,在适当条件下同脂多糖发生染色反应 ,在 5 5 0 nm波长下 ,反应体系的吸光值同脂多糖含量呈线性相关。相关系数为 0 .9993,最低检出限为 10 μg/m L,相对标准偏差为 1.6 2 ,平均回收率为 (10 5± 2 .18) %。 相似文献
35.
《The Professional geographer》2013,65(4):452-458
The foundations of modern Romanian geography were laid by one man, Simion Mehedin?i, at the beginning of the twentieth century. His systematic view of a unified geography developed from the ideas formed during his education in France and Germany, particularly under the influence of Ratzel. His ideas, propagated by his followers, are still regarded as valid by the present generation of Romanian geographers. 相似文献
36.
本文介绍了1994年7月SL-9彗星撞击木星期间3.6cm和12cm射电连续谱观测的结果.在3.6cm波长上,撞击事件无明显的视效应,在12cm波长上,木星的射电平均视流量增加约20%. 相似文献
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The normalized difference vegetation index (NDVI) is used extensively to describe vegetation cover and ecological environment
change. The purpose of this study was to contrast the response of different tree species growing in the same habitat to
climate change and retrieve past NDVI using tree-ring width data from tree cores collected from the transitional zone of Pinus
tabulaeformis and Picea crassifolia in the Luoshan Mountains in the middle arid region of Ningxia. Correlation analysis indicated
that radial growth of P. tabulaeformis is more sensitive to precipitation and temperature change than that of P. crassifolia.
Natural factors such as water availability and heat at this elevation are more suited to the growth of P. crassifolia, and are more
advantageous to its renewal and succession. P. crassifolia is probably the better of the two species for protecting the forest
ecosystem and conserving water in the Luoshan desertification area. Ring width of P. crassifolia correlates significantly with
average NDVI for April–May (r =0.641, p <0.01), and both of them are influenced positively by precipitation in April–May.
The reconstructed NDVI for 1923–2007 shows the relatively low vegetation cover occurred in the 1920s–1930s, the
1960s–1970s, and the early 21st century. The reconstructed NDVI better reflected the drought climate in the study area. 相似文献
39.
Annual dissolved fluxes from Central Nepal rivers: budget of chemical erosion in the Himalayas 总被引:2,自引:0,他引:2
Christian France-Lanord Matthew Evans Jean-Emmanuel Hurtrez Jean Riotte 《Comptes Rendus Geoscience》2003,335(16):1131-1140
Annual dissolved element fluxes of Himalayan rivers from Central Nepal are calculated using published river discharge and a new set chemical data of rivers, including monsoon sampling. These are used to study the control on chemical erosion of carbonate and silicate over the whole basin. Chemical erosion of carbonate is mainly controlled by the river runoff but it can be limited by the availability of carbonate in limestone-free basin. Chemical erosion of silicate is well correlated to the runoff. However differences between High Himalayan and Lesser Himalayan basins suggest that physical erosion may also play an important control on silicate weathering. To cite this article: C. France-Lanord et al., C. R. Geoscience 335 (2003). 相似文献
40.
Franois Chabaux Jean Riotte Anne-Dsire Schmitt Jean Carignan Pierre Herckes Marie-Claire Pierret Henry Wortham 《Comptes Rendus Geoscience》2005,337(16):4612
Major and trace element concentrations, as well as Sr and U isotope ratios, were measured in rainwater samples collected in three different locations in Alsace (East of France) and Luxembourg: a mid-altitude mountain site (Aubure Environment HydroGeochemical Observatory), an urban site (Strasbourg) and a peri-urban site located in an area of well developed industrial activity (Esch-sur-Alzette in Luxembourg). Results highlight the quite high spatial and temporal variability of the chemical and isotopic characteristics of rainwater at the regional scale. They also suggest a quite systematic contribution of a local component in the chemical composition of rainwater. In urban and peri-urban sites, the local component is certainly linked to human activities, as it is well illustrated in this study with the Esch-sur-Alzette samples. On the other hand, for the Aubure site, i.e. a small forested watershed of mid-altitude mountain, data presented in this study demonstrate the influence of the vegetation on the chemical composition of rainwater for alkali and calc-alkali elements, as well as for the Sr isotope ratios. Such a result questions the reliability of the method classically used to estimate the rainwater contribution on the river chemical budget. In addition, data of the present study confirm the very low content of uranium in rainwater and demonstrate, especially through the U isotope analysis of Aubure rainwater, the negligible effect of rainwater on U budget of river waters. This work thus outlines the property of U to be a geochemical tracer specific of weathering fluxes carried by rivers. To cite this article: F. Chabaux et al., C. R. Geoscience 337 (2005). 相似文献