1,721,192 research outputs found
Prospettive sulla valorizzazione degli olii estratti dalle piante come fonte di materie prime per l'industria chimica: leEuphorbiedella Sardegna
Full text linkIn the present paper the author describes the research carried out at the University of Sassari on the utilization as fuels or chemical feedstocks of oils derived from plants. Examination of the results obtained with oils derived fromEuphorbiaevegetanting in Sardinia suggests to orient the studies toward the isolation of fine chemicals rather then toward the utilization as fuels, directly
or after pyrolysis. This conclusion is supported by the
comparison of data on three SardinianEuphorbiaeand by considerations on the Sardinian land
Introduction to the Landscapes and Landforms of Italy
No full textItalian landscapes and landforms show an outstanding variety due to long-term geological processes and climate changes. Landscape diversity in many regions of the country is also deeply connected with human presence since ancient times, cultural and political diversity as well as highly varied customs and traditions. Also for these reasons, Italy has been a privileged destination for generations of travellers, intellectuals and artists attracted by fascinating landscapes which perfectly frame architecture and art masterpieces. Nowadays Italy is one of the most important tourist destinations in the world, with more than 50 million international visitors every year
Si vede la Stella Polare - La difficile rotta tracciata dai nonni e percorsa dai nipoti
No full textUna descrizione soggettiva sui rapporti tra le generazioni a cavallo del cambio di millennio
The Dolomite Landscape of the Alta Badia (Northeastern Alps): A Remarkable Record of Geological and Geomorphological History
No full textThe Alta Badia (Eastern Dolomites) well synthetizes the remarkable geological and
geomorphological features that enabled the Dolomites to be inscribed in the UNESCO
World Heritage List. Spectacular dolomite mountain groups, built up during the Triassic in
coral-reef and tidal-plain environments, stand out of mild slopes made up of clayey terrains
deposited in deep inter-reef basins. The landscape is characterized by pale-coloured
dolomite cliffs, towers and pinnacles rising above wide talus deposits and gentle grassy
foothills witnessing a complex geomorphological long-term evolution. Pleistocene glaciers
profoundly shaped the valleys and, at their retreat, periglacial and gravity-induced
processes had a major role in slope modelling. Landslides have affected the valleys since
the Lateglacial leaving a clear inprint on the landscape, as well as Man in recent times
Clima e attività umane come cause dei cambiamenti fluviali - Il caso del Fiume Po
No full textI cambiamenti nella dinamica fluviale possono essere imputati a cause diverse; tra queste le principali sono sicuramente quelle climatiche e quelle antropiche. Spesso i cambiamenti sono repentini anche se la loro preparazione è avvenuta in tempi molto lunghi; di fatto in queste fasi preparatorie, il sistema fluviale si è avvicinato a soglie limite che una volta superate hanno provocato una brusca accelerazione nei processi di erosione o di sedimentazione fluviale. I più conosciuti effetti sull’ambiente fluviale che si manifestano in queste occasioni sono, infatti, inversioni di tendenza tra fasi di sedimentazione e fasi di erosione. L’incisione o la sedimentazione nei corsi d’acqua dipendono dal rapporto tra portata solida e portata liquida nel fiume pur non dovendosi trascurare altri fattori come ad esempio la le variazioni del livello di base o cause tettoniche. Quando il rapporto è spostato verso la portata solida risulta fondata la possibilità che si verifichino processi di aggradazione, mentre se il rapporto è spostato verso la portata liquida aumentano le probabilità che si manifestino processi erosivi.Durante l’evoluzione recente della Pianura Padana si assiste a momenti contraddistinti da forte sedimentazione, ad esempio quello verificatosi durante l’Ultimo Massimo Glaciale, e da momenti di intensa erosione, come ad esempio ai nostri giorni oppure durante il Tardiglaciale. Alcuni di questi eventi sono chiaramente influenzati da cause climatiche (fasi glaciali e deglaciazione) altri da cause diverse tra cui quelle antropiche sono spesso preponderanti.In questo lavoro si cercherà di definire alcuni di questi momenti significativi nell’evoluzione postglaciale della Pianura Padana e di analizzare anche situazioni in cui entrambe le cause si sovrappongono e si mascherano reciprocamente. Changes of fluvial dynamics in a plain are due to many causes. It is so difficult to evaluate one as the main cause of the environmental changes in a fluvial plain and in its hydrographic network. Rivers, in fact, can suffer rapid and significant changes in their behavior as consequence also of moderate but extended variations of hydrological parameters that can be recognized only by instrumental measures. Perhaps fluvial system such as many natural systems can maintain, between characteristic thresholds, a certain energetic inertia in its behavior. When a threshold is exceeded fluvial processes change quickly and fluvial landforms may be strongly modeled.In the fluvial system events that produce more rapid and disturbing transformations are those that induce erosion rather than sedimentation. Historically in fact, exaggerated sedimentation problems have been impossible to manage during several decades when man constrains river in a fixed tracks between narrow embankments. Before systematic human management of the fluvial system, aggradation phases spread out into large areas while erosion phases are all the time concentrated along riverbed. Incision or aggradation depends by ratio solid/water discharge in a riverbed. More the ratio is unbalanced towards sediment availability, higher sedimentation rate is; on the contrary, scarceness sediment availability induces tendency to erosion. Obviously, total discharge and velocity play an important role. In fact a river inclined to erosion processes but characterized by scarce total discharge and velocity is not able to evacuate large gravels or large amount of sediment in a short time.The present day generalized erosion phases in northern Italy are considered the consequence of the growing human impact after the unity of Italy. On the contrary in the past, when human impact was less important, fluvial dynamic was principally controlled by natural causes. Among them, climatic changes have been the most remarkable cause of fluvial modifications.In the Po Plain, the climate change at the end of the Last Glacial Maximum (LGM), that caused the changes in fluvial dynamics, was the last larger formative event.In the northern foothills, Late Pleistocene palaeochannels indicate several cases of underfit streams among the northern tributaries of the Po River. On the other hand, on the southern side of the Po Plain no geomorphological evidence of similar discharge reduction has been found. Here stratigraphic sections, together with archaeological remnants buried under the fluvial deposits, show a reduction in the grain-size of fluvial sediments after the 10th millennium B.C. During the Holocene, fluvial sedimentation became finer, and was characterised by minor fluctuation in the rate of deposition, probably related to shorter and less intense climatic fluctuations.Given the high rate of population growth and the development of human activities since the Neolithic Age, human influence on fluvial dynamics, especially since the Roman Age, prevailed over other factors (i.e. climate, tectonics, vegetation, etc.). During the Holocene, the most important changes in the Po Plain were not modifications in water discharge but in sediment supply. At present, abandonment of the mountainous region leading to reafforestation and artificial control in the mountain sector of the basins but also in-channel quarrying (now illegal but very intense in the 1960s and 1970s) are causing erosion along rivers and large sectors of the Adriatic coast. These changes are comparable to those occurring in basins of other Mediterranean rivers
Geografia al tempo di Google Map
No full textConsiderazioni sulla didattica della geografia nella scuola primarie e secondaria di primo grado. Riferimenti alla formazione degli insegnanti di geografia
The Great Diversity of Italian Landscapes and Landforms: Their Origin and Human Imprint
No full textAn outstanding variety of landscapes and landforms are present in Italy due to its complex geological history, repeated climate changes and increasing human impact through time. This chapter highlights the reasons for the geological and geomorphological diversity of the country by illustrating its geological evolution since the Mesozoic, outlining the paleogeographic changes that occurred as a consequence of Quaternary climate variations, and tracing the unique human civilization history that has so strongly influenced landscape evolution since the Neolithic . Special attention is devoted to the complex history of the country, where peoples coming from different geographical areas met each other contributing to make Italy a compendium of cultural diversity capable of attracting travellers from all over the world. Landscape conservation and protection are finally taken into account
Prospettive della reazione di idroformilazione nella sintesi di composti biologicamente attivi
Full text linkIl nostro gruppo sta conducendo uno studio su complessi di rodio con una nuova classe di
leganti idrosolubili di origine proteica, tali complessi impiegati nell’idroformilazione bifasica in
solvente acquoso di diversi substrati hanno fornito buoni risultati
I segreti della Terra – Corso di Geografia Fisica e Geomorfologia.
No full textTrattato di geografia fisica e geomorfologi
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