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Between 1993 and 1995 a system of six intensive monitoring stations in representative stands of Norway spruce (Picea abies), sessile oak (Quercus robur) and Scots pine (Pinus sylvestris) were installed in forests of Saxony (Germany), they are integrated in the European Level II - Programme. As a complementary system, and in addition to the annual nation-wide forest decline survey, 280 sites within the forest soil condition survey (European Level I - Programme) have been examined since 1992. The results of deposition monitoring show that until 1997 the acidity in precipitation and troughfall still was very high, despite of strong reductions in industrial emissions between 1989 and 1992. The annual fluxes (hydrological year 1996) of sulphur in throughfall ranged between 16 and 77 kg-ha-1, whereas the fluxes of total inorganic N varied between 17 and 46 kg-ha-1. The forest soils show high degrees of acidification with only low base saturation. In most cases the nutrient status of the soils has to be improved in the course of a regeneration programme in order to rebuild more natural forest ecosystems. 相似文献
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Raben J 《Science (New York, N.Y.)》1985,228(4698):434-438
The earliest and still most prevalent use of computers in the humanities is the compilation of concordances, rationalized vocabulary lists for literary works. The residue of these efforts has created the potential for extensive databases of natural-language text for a wide range of studies and for instruction. As yet, however, computer-aided instruction has focused on mechanical skills, like spelling and grammar. With rapid advances in storage (like videodisks) and in communications between computers, humanists are finding a challengingly altered environment in which to study and teach. 相似文献
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