全文获取类型
收费全文 | 107篇 |
免费 | 10篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 6篇 |
大气科学 | 3篇 |
地球物理 | 33篇 |
地质学 | 54篇 |
海洋学 | 6篇 |
天文学 | 14篇 |
自然地理 | 2篇 |
出版年
2023年 | 1篇 |
2021年 | 3篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 5篇 |
2017年 | 6篇 |
2016年 | 6篇 |
2015年 | 8篇 |
2014年 | 7篇 |
2013年 | 4篇 |
2012年 | 6篇 |
2011年 | 9篇 |
2010年 | 8篇 |
2009年 | 10篇 |
2008年 | 6篇 |
2007年 | 5篇 |
2006年 | 5篇 |
2005年 | 8篇 |
2004年 | 4篇 |
2003年 | 4篇 |
2002年 | 2篇 |
2001年 | 2篇 |
1998年 | 1篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
排序方式: 共有118条查询结果,搜索用时 15 毫秒
111.
112.
Soil C and N response to changes in winter precipitation in a subalpine forest ecosystem,NW Italy 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《水文研究》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Among the potential effects of climate change on subalpine forest ecosystems during the winter season, the shift in snowline towards higher altitudes and the increase in frequency of rain events on the snowpack are of particular interest. Here, we present the results of a 2‐year field experiment conducted in a forest stand (Larix decidua) in NW Italy at 2020 m a.s.l. From 2009 to 2011, we monitored soil physical characteristics (temperature and moisture), and soil and soil solution chemistry, in particular carbon (C) and nitrogen (N) forms and their change in time, as affected by simulated late snowpack accumulation and rain on snow events. Late snowpack accumulation determined a stronger effect on soil thermal and moisture regimes than rain on snow events. Also soil chemistry was significantly affected by late snowfall simulation. Although microbial biomass C and N were not reduced by soil freezing, soil contents of the more labile dissolved organic carbon and inorganic N increased when the soil was affected by mild/hard freezing. Variations in the soil solution were shifted with respect to those observed in soil, with an increase in N‐NO3? concentrations occurring during spring and summer. This study highlights the potential N loss in subalpine soils under changing environmental conditions driven by a changing climate. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
113.
114.
115.
Asbestos fibre identification vs. evaluation of asbestos hazard in ophiolitic rock mélanges,a case study from the Ligurian Alps (Italy) 总被引:1,自引:1,他引:0
Gianluca Vignaroli Paolo Ballirano Girolamo Belardi Federico Rossetti 《Environmental Earth Sciences》2014,72(9):3679-3698
In recent years, the high incidence of harmful health effects through inhalation of airborne asbestos from amphibole-bearing rock mélanges has been thoroughly documented. Here, we present a field-based, multi-scale geological approach aimed at illustrating the occurrence of amphibole fibrous mineralisation in an ophiolitic suite from the Ligurian Alps (Italy) and discussing the implication on in situ determination of the asbestos hazard. The rock mélange is composed of plurimetre-sized blocks of different lithotypes (metagabbro, serpentinite, chloritoschist) juxtaposed by the meaning of tectonic structures. The geological-structural survey revealed that the fibrous mineralisation is localised in specific structural sites of the rock volume, including veins and schistosity. Both micro-chemical and crystal structure analyses on selected fibrous samples revealed that actinolite fibres grow in veins within the metagabbro and in chloritoschists, while fibrous tremolite occurs in serpentinite schistosity. The morphological features of these amphibole fibres have been analysed in TEM images and used for classifying them as “asbestiform” or “non-asbestiform”. The results show that the asbestos hazard determination is not unequivocally identified when different procedures for asbestos fibre identification and classification are applied. This may have impact on normatives and regulations in defining environmental hazards due to asbestos occurrence. 相似文献
116.
Silvio Mollo Pierdomenico Del Gaudio Guido Ventura Gianluca Iezzi Piergiorgio Scarlato 《Lithos》2010,118(3-4):302-312
The compositional variation of clinopyroxene and the partitioning of major elements between clinopyroxene and melt are estimated as a function of the cooling rate. Clinopyroxenes were crystallized under variable cooling regimes (15, 9.4, 3, 2.1, and 0.5 °C/min from 1250 down to 1000 °C) and at isothermal conditions of 1000 °C from a basaltic composition at a pressure of 500 MPa under anhydrous and hydrous (H2O = 1.3 wt.%) conditions. The clinopyroxene chemistry shows that, as the cooling rate increases, crystals are progressively depleted in Ca, Mg, Fe2+ and Si and enriched in Na, Fe3+, Al (mainly AlIV), and Ti. Di and Hd versus CaTs and CaFeTs form a continuous binary solid solution characterized by higher amounts of tschermakitic components with increasing cooling rate. Two parameters (DH = Di + Hd and TE = CaTs + CaFeTs + En) are calculated to describe the effect of cooling rate on the clinopyroxene composition. The variation of DH/TE with increasing cooling rate evidences the kinetic process induced by rapid cooling in basic rocks under hydrous and anhydrous conditions.Dynamic crystallization conditions affect the partitioning of major elements between clinopyroxene and melt; with increasing cooling rate, the value of crystal–melt partition coefficient departs from that obtained at the isothermal condition. However, in spite of these variations, the values of cpx–meltKdFe–Mg remain almost constant. Therefore, the Fe2–Mg exchange between clinopyroxene and melt is not suitable to prove the (dis)equilibrium conditions in basaltic cooling magmas, giving rise to possible mismatches in the application of thermobarometers. The results of our study are consistent with that observed at the margin of dikes or in the exterior portions of lavas, where the cooling rate is maximized and disequilibrium compositions of clinopyroxene have been found. 相似文献
117.
Tewodros Rango Riccardo Petrini Barbara Stenni Gianluca Bianchini Francesca Slejko Luigi Beccaluva Tenalem Ayenew 《Applied Geochemistry》2010,25(12):1860-1871
Water samples from cold and geothermal boreholes, hot springs, lakes and rivers were analyzed for δD, δ18O and 87Sr/86Sr compositions in order to investigate lake water–groundwater mixing processes, water–rock interactions, and to evaluate groundwater flow paths in the central Main Ethiopian Rift (MER) of the Ziway–Shala basin. Different ranges of isotopic values were recorded for different water types: hot springs show δ18O −3.36 to +3.69 and δD −15.85 to +24.23, deep Aluto-Langano geothermal wells show δ18O −4.65 to −1.24 and δD −12.39 to −9.31, groundwater wells show δ18O −3.99 to +5.14 and δD −19.69 to +32.27, whereas the lakes show δ18O and δD in the range +3.98 to +7.92 and +26.19 to +45.71, respectively. The intersection of the Local Meteoric Water Line (LMWL: δD = 7 δ18O + 11.2, R2 = 0.94, n = 42) and the Local Evaporation Line (LEL: δD = 5.63δ18O + 8, n = 14, R2 = 0.82) was used to estimate the average isotopic composition of recharge water into the basin (δD = −5.15 and δ18O = −2.34). These values are depleted if compared with the modern-day average precipitation, presumably indicating paleo-groundwater components recharged during previous humid climatic phases. The measured stable isotope values indicate that the geothermal wells, some of the hot springs and groundwater wells mainly consist of meteoric water. The Sr isotopic signatures in all waters are within the range of the Sr isotopic composition of the rift basalts and rhyolites. The variability of Sr isotopic data also pinpoints complex water–rock interaction and mixing processes in groundwater and surface water. The 87Sr/86Sr ratio ranges from 0.70445 to 0.70756 in the hot springs, from 0.70426 to 0.70537 in two deep geothermal wells, and from 0.70673 to 0.70721 in the rift lakes Ziway, Langano, Shala and Awasa. The radiogenic composition recorded by the lakes indicates that the input water was predominantly affected by progressive interaction with rhyolitic volcanics and lacustrine sediments. 相似文献