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41.
42.
Recent transfers of potential marine wealth to coastal states, resulting from the Third United Nations Convention on the Law of the Sea, have enhanced our awareness that the marine sector might ultimately prove to be a new frontier. The objective of this paper is to initiate work toward the development of a systematic appraoch to the economics of this sector. To this end, the marine sector is assumed to be the fourth factor of production, taking its place with the traditional trio of land, capital and labor. The productivity of this sector is described and analyzed with the aid of a simple general equilibrium model. 相似文献
43.
44.
Trees may die in forest stands over relatively large areas for obvious reasons, such as fire, flooding, severe drought, strong
air pollution, and insect outbreaks. However, in many cases, stand-level dieback occurs without an obvious reason and then
its etiology becomes more complicated, involving a combination of factors. The dieback structure, its symptomatology, and
its spatial and temporal patterns may be used to identify these factors at least at the generic level. Moreover, observations
of the dieback-associated vegetation dynamics can be used to draw inferences about the dieback process. In addition to biotic
diseases and environmental changes or short-term recurring stresses, local site characteristics and the life history of the
stand must be considered in a more universally applicable theory for stand-level dieback. This is further explained by a simplified
model related to the decline disease concept of Houston. 相似文献
45.
Prof. Tianchi Li Dr. 《GeoJournal》1988,17(4):649-657
This paper examines the regional climatic and environmental changes from the late Pleistocene to middle Holocene in Central-East Asia. A review is made of the published literature that are specific to pelaeoclimate and physical environment in some geographical regions.It is shown that (1) during the late Pleistocene the annual mean temperature was 5°–6° C lower than present in Qinghai-Xizang (Tibet) plateau, 6° to 9° C lower than today in NE China, 6° C lower than today in E China, and 4° C lower than present in Taiwan island; (2) during the middle Holocene, the annual mean temperature was 4° C warmer than present in Qinghai-Xizang (Tibet) plateau, 3° to 4° C warmer than today in NE China, 2° to 3° C warmer than today in Shanghai area, and only 2° to 2.5° C warmer in Taiwan island. 相似文献
46.
47.
Doumenge JP 《GeoJournal》1988,16(2):143-156
Demographic, sociocultural, economic, and political trends in the French islands of the South Pacific are examined. Consideration is given to population distribution, internal and interisland migration, economical assets and weaknesses, political relationship with France, and cultural traditions unique to New Caledonia, French Polynesia, and Wallis and Futuna Islands. 相似文献
48.
Summary The crystal structure of the tetragonal fumarole mineral nabokoite, Cu7TeO4(SO4)5 · KCl (a=9.833 (1).Å,c=20.591(2) Å, space groupP 4/ncc, Z=4) was determined by single crystal X-ray methods on type material from Kamchatka. The structure contains complicated {[CU7TeO4(SO4)4]SO4} sheets that are intercalated by K and Cl ions. Nabokoite presents the first example of a Te(IV)O4 pyramid with exactly tetragonal symmetry. The K ions have a somewhat unusual, rather flat coordination.
With 2 Figures 相似文献
Die Kristallstruktur des Nabokoits, Cu7TeO4(SO4)5 · KCl: Das erste Beispiel für eine Te(IV)O4-Pyramide mit exakt tetragonaler Symmetrie
Zusammenfassung Die Kristallstruktur des tetragonalen Fumarolenminerals Nabokoit, Cu7TeO4(SO4)5 · KCl (a=9,833(1)Å,c=20,591(2)Å, RaumgruppeP 4/ncc, Z=4) wurde an Typ-Material von Kamtschatka mit Röntgen-Einkristallmethoden bestimmt. Die Struktur enthält komplizierte [Cu7TeO4(SO4)4]SO4-Schichten, die durch K- und Cl-Ionen verbunden werden. Nabokoit liefert das erste Beispiel für eine Te(IV)O4-Pyramide mit exakt tetragonaler Symmetrie. Die K-Ionen haben eine etwas ungewöhnliche, ziemlich flache Koordination.
With 2 Figures 相似文献
49.
On atmospheric vortex streets in the wake of large islands 总被引:1,自引:0,他引:1
Prof. Dr. D. Etling 《Meteorology and Atmospheric Physics》1989,41(3):157-164
Summary Results from laboratory experiments on stably stratified flows over three-dimensional obstacles are related to atmospheric vortex streets formed in the lee of large islands. A quasi horizontal flow around the island can be expected if stable stratification favours the formation of a so-called dividing streamline below the islands top. The subsequent shedding of vortices with vertical axis from islands may then be due to viscous boundary layer separation, but also other possible mechanisms of vortex shedding in stably stratified flows are discussed.With 6 Figures 相似文献
50.
After a short introduction into the field of the zeolites the use of the molecular sieve 4 A as builder in the washing process is treated. Structure and ion-exchange capacity are characterized, the mechanism of the elimination of calcium-ions is described and the environmental behaviour is examined. Finally, other potential applications of zeolitic ion exchangers are presented. 相似文献