全文获取类型
收费全文 | 5518篇 |
免费 | 6篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 19篇 |
大气科学 | 1010篇 |
地球物理 | 1267篇 |
地质学 | 3079篇 |
海洋学 | 42篇 |
天文学 | 60篇 |
综合类 | 3篇 |
自然地理 | 46篇 |
出版年
2013年 | 62篇 |
2006年 | 30篇 |
1997年 | 33篇 |
1996年 | 74篇 |
1995年 | 45篇 |
1994年 | 39篇 |
1993年 | 58篇 |
1992年 | 147篇 |
1991年 | 153篇 |
1990年 | 140篇 |
1989年 | 135篇 |
1988年 | 136篇 |
1987年 | 173篇 |
1986年 | 130篇 |
1985年 | 114篇 |
1984年 | 153篇 |
1983年 | 168篇 |
1982年 | 183篇 |
1981年 | 184篇 |
1980年 | 151篇 |
1979年 | 185篇 |
1978年 | 159篇 |
1977年 | 149篇 |
1976年 | 116篇 |
1975年 | 139篇 |
1974年 | 125篇 |
1973年 | 141篇 |
1972年 | 129篇 |
1971年 | 137篇 |
1970年 | 143篇 |
1969年 | 100篇 |
1968年 | 130篇 |
1967年 | 123篇 |
1966年 | 85篇 |
1965年 | 96篇 |
1964年 | 100篇 |
1963年 | 44篇 |
1962年 | 91篇 |
1960年 | 104篇 |
1959年 | 35篇 |
1957年 | 41篇 |
1956年 | 37篇 |
1955年 | 40篇 |
1954年 | 67篇 |
1953年 | 38篇 |
1952年 | 49篇 |
1951年 | 38篇 |
1950年 | 61篇 |
1949年 | 44篇 |
1948年 | 33篇 |
排序方式: 共有5526条查询结果,搜索用时 31 毫秒
51.
Summary A Mg-Al spinel from a xenolith found in the Sacrofano volcanic area (Latium, Italy) was investigated by X-ray single crystal diffraction and electron microprobe. Its main structural parameters were: a0 = 8.0922(3) Å and the oxygen coordinate u = 0.26213(4), which gave to tetrahedral and octahedral bond distances of 1.9220(6) Å and 1.9299(3) Å respectively. Cation distribution, obtained from structural and chemical data, showed a very high Mg-Al disorder, with an Al(T) content of 0.205 and an inversion parameter, i, of about 0.23. Comparison with the cation distribution of a spinel with similar chemical composition but occurring in chlorite schists (Shishimsk Mountains, Urals, Russia) with a0 = 8.1003(3) Å and u=0.26330(3), and with data from the literature concerning spinels from metamorphosed limestones (Kalkbro, Sweden) and websteritic dikes (Balmuccia, Italy), all characterized by much lower Mg-Al disorder (i about 0.13–0.12), suggests a completely different thermal history, with rapid cooling rates and consequent high closure temperature of intracrystalline exchange, consistent with the Sacrofano geological environment.
Kristallchemie eines stark ungeordneten, natürlichen Mg-Al-Spinells
Zusammenfassung Ein Mg-Al-Spinell aus einem Xenolith des Vulkangebiets von Sacrifano (Latium, Italien) wurde mit Röngten-Einkristallmethoden und der Elektronenmikrosonde untersucht. Die wichtigsten Strukturparameter sind ao = 8,0922(3) Å und die Sauerstoffkoordinate u = 0,26213(4), was zu den tetraedrischen und oktaedrischen Bindungsabständen von 1,9220(6) Å bzw. 1,9299(3) Å führt. Die aus den strukturellen und chemischen Daten erhaltene Kationenverteilung zeigt eine sehr starke Unordnung Mg-Al mit einem Al (T)-Gehalt von 0,205 und einem Inversionsparameteri von ca. 0,23. Der Vergleich mit der Kationenverteilung eines Spinells ähnlicher chemischer Zusammensetzung, aber aus Chloritschiefern (Schischimsk-Berge, Ural, Rußland) mit a0 = 8,1003(3) Å und u=0,26330(3), sowie mit Literaturdaten über Spinelle aus metamorphen Kalken (Kalkbro, Schweden) und websteritischen Gängen (Balmuccia, Italien), die alle durch eine viel geringere Mg-Al-Unordnung charakterisiert sind (i etwa 0,13–0,12), weist auf eine völlig andere thermische Geschichte hin, und zwar mit rascher Abkühlungsgeschwindigkeit und hoher Schließungstemperatur des intrakristallinen Austausches, was mit den geologischen Verhältnissen von Sacrofino in Übereinstimmung steht.相似文献
52.
Dr. W. R. Taylor R. W. Page G. Esslemont N. M. S. Rock D. I. Chalmers 《Mineralogy and Petrology》1995,52(3-4):209-230
Summary Rare-metals mineralization of the Brockman deposit (Halls Creek Mobile Zone, NW Australia) is hosted in a fluorite-bearing, rhyolitic volcaniclastic unit informally termed the Niobium Tuff. The Tuff, more correctly described as a tuffaceous volcaniclastic deposit, is the lowermost unit of a sequence of trachyte-to-rhyolite lavas, trachyandesite subvolcanic rocks, and volcaniclastic units of the Brockman volcanics located within the Halls Creek Group, a thick, early Proterozoic volcano-sedimentary sequence. High precision SHRIMP ion-microprobe zircon dating of the Niobium Tuff gives an eruption age of 1870 ± 4 Ma. Regional geochronological constraints indicate the Niobium Tuff was deposited about 15 Ma before major orogenic activity affected the area. Despite folding, faulting and low-grade metamorphism, the Brockman volcanics show excellent preservation of primary volcanological features, including pillow-lavas and pillow-breccias, that suggest a dominantly subaqueous, below-wave-base emplacement environment. The style of eruption products and magma volume constraints suggest the trachyte-dominated volcanics were erupted from a small shield volcanic complex probably in a rift-related basin in a shallow-marine setting. The tectonic setting was intraplate but differs from most Tertiary to recent trachyte volcanic complexes which are largely subaerial, are built on relatively thick continental crust, and show no post-eruptive orogenic history. Brockman-style rare-metal deposits are characterized by preservation of subaqueous volcanics beneath a thick sedimentary sequence, eruption of early incompatible-element enriched products followed by less differentiated magmas, and fine-grained mineralogy influenced by alteration processes. Prospects exist for discovery of analogous deposits, particularly in early Proterozoic mobile belts and Tertiary intraplate shield volcanic provinces.
With 5 Figures
Deceased 相似文献
Geologie der an Vulkanite gebundenen Seltene-Metalle-Lagerstätte Brockman, Halls Creek Mobile Zone, Nordwest-Australien. I. Vulkanologie, Geochronologie und Petrographie der Brockman-Vulkanite
Zusammenfassung Selten-Metall-Vererzung der Brockman-Lagerstätten (Halls Creek Mobile Zone, NW Australien) sitzt in einer Fluorit-führenden, rhyolitischen vulkanoklastischen Einheit auf, die informell als der Niob-Tuff bezeichnet wird. Es handelt sich hier um ein vulkanoklastisches Tuff-Sediment; dieses ist die unterste Einheit einer Abfolge vor Trachyt bis Rhyolit-Laven, trachyandesitischen Subvulkaniten and vulkanoklastischen Einheiten der Brockman Vulkanite innerhalb der Halls Creek Gruppe, einer mächtigen frühproterozoischen vulkanosedimentdren Abfolge. Prüzisionsdatierungen des Niob Tuffs mit der SHRIMP Ionen-Mikrosonde ergeben ein Eruptionsalter von 1870 +-4 Millionen Jahren. Regionale geochronologische Zusammenhänge zeigen, daß der Niob Tuff etwa 15 Millionen Jahre vor einer größeren Orogenese, die das Gebiet betroffen hat, abgelagert wurde. Trotz Faltung, Bruchtektonik and niedriggradiger Metamorphose zeigen die Brockman-Vulkanite einen hervorragenden Erhaltungszustand primärer vulkanologischer Erscheinungen. Diese urnfassen auch Kissenlaven und KissenBreckzien, die eine vorwiegend subaquatische Ablagerung in ruhigem Wasser erkennen lassen. Die Art der Eruptionsprodukte and das Magmavolumen zeigen, daß die Trachytdominierten Vulkanite von einem kleinen Schildvulkan stammer, wahrscheinlich in einem Becken in einer Rift-Situation im seichten marinen Milieu. Die tektonische Situation war intraplate, aber unterscheidet sich von den meisten tertiären bis rezenten trachytischen Vulkan-Komplexen, die hauptsächlich subaerisch sind, auf einer relativ mächtigen kontinentalen Kruste aufsitzen, and keine post-eruptive orogene Entwicklung zeigen. Seltene-Metalle-Lagerstatten des Brockman-Typs rind durch die Erhaltung subaquatischer-Vulkanite unterhalb einer machtigen sedimentdren Abfolge gekennzeichnet; welters durch frühe Eruptionsprodukte, die an inkompatiblen Elementen angereichert sind, auf die dann weniger differenzierte Magmen folgten, und schließlich durch einen feinkörnigen Mineralbestand, der vor Umwandlungsprozessen betroffen war. Es besteht die Möglichkeit der Entdeckung analoger Lagerstätten, besonders in frühproterozoischen mobilen Gürteln und in tertidren intraplate Schildvulkan Provinzen.
With 5 Figures
Deceased 相似文献
53.
Early miocene post-collisional calc-alkaline magmatism along the easternmost segment of the periadriatic fault system (Slovenia and Croatia) 总被引:1,自引:0,他引:1
Dr. R. Altherr Dr. B. Lugović Dr. H. -P. Meyer Dr. V. Majer 《Mineralogy and Petrology》1995,54(3-4):225-247
Summary Early Miocene calc-alkaline igneous rocks from the easternmost segment of the Periadriatic fault system can be subdivided into two series of different alkalinity: (1) Volcanics which occur in the vicinity of the Velenje-Rogatec Line range from high-alumina basalt via low-K and medium-K andesites to medium-K dacites. (2) In the Pohorje Mountains mafic rocks are lacking. A high-K tonalitic pluton crystallized at pressures of about 0.7 GPa as indicated by Al-in-hornblende barometry and accessory magmatic epidote. Rapid exhumation of the tonalite during dextral transtension along the Periadriatic fault system is indicated by tonalitic pebbles in Helvetian (?) clastic sediments. High-K andesitic to dacitic volcanics are interlayered with, and dikes cut, the clastic sediments.Compositional variations shown by the volcanics from the Velenje-Rogatec Line are consistent with fractionation of the observed phenocryst assemblages (olivine, plagioclase, clinopyroxene, orthopyroxene, titanomagnetite). Substantial fractionation of plagioclase is indicated by decreasing Sr/Nd and Sr/Y values and increasing negative Eu anomalies with increasing SiO2. All samples have chondrite-normalized HREE > 9.6 and low (Tb/Yb)n ratios (1.29–1.08). With increasing SiO2, the abundances of HREE and Y (18 to 39 ppm) increase and those of Sc (32.5 to 20.9 ppm) decrease slightly. These features, together with low Hf/Lu and Zr/Y values (10.1–5.7 and 5.7–3.6, respectively), rule out garnet as a major fractionating phase. Since (La/Yb)n values (3.24–6.59) do not increase with SiO2 and chondrite-normalized REE patterns do not show concave-upward shapes, fractionation of amphibole was probably insignificant. Although Rb/Cs values ( 18) are generally low, a significant contribution by continental crustal materials to the magmas by an AFC process is suggested by negative correlations of Nb/U(7.16 to 3.14) and Nb/Th(2.14 to 0.87) values with SiO2, as well as by low Hf/Ta(7.8–3.4), and in part also by K/Rb (340-71) and Zr/Rb (5.0–1.7) values.Rocks from the Pohorje Mountains have high abundances of U. Values of Nb/U and Nb/Th are low (3.55 to 1.85 and 1.27 to 0.64, respectively) and are negatively correlated with SiO2. These features, in combination with high values of Ba/Nb (56 to 93), Ba/La (23–30), and Rb/Cs (19–56), as well as with previously published 18O values ( 9) for the tonalite indicate a substantial contribution of the continental crust to these magmas. High Sr abundances (455 to 984 ppm) and moderate negative Eu anomalies suggest that fractionation of plagioclase was of minor importance. Although the rocks have relatively low Sc (9.3 to 3.8 ppm) and Y (21 to 14 ppm) contents, low (Tb/Yb)n values (1.67–1.14) indicate that garnet was not a major fractionating phase. Instead, fractionation of amphibole is a viable mechanism to explain the combination of high (La/Yb)n (21.8–13.1) and low (Tb/Yb)n.
With 9 Figures 相似文献
Untermiozäner, kalkalkaliner Post-Kollisions-Magmatismus entlang des östlichsten Segmentes des periadriatischen Störungssystems (Slowenien und Kroatien)
Zusammenfassung Untermiozäne Kalkalkali-Magmatite aus dem östlichen Bereich des Periadriatischen Lineaments gliedern sich in zwei Serien unterschiedlicher Alkalinität: (1) Entlang der Velenje-Rogatec-Linie treten High-Al-Basalte, Low-K- und Medium-K-Andesite und Medium-K-Dazite auf. (2) Im Pohorje-Gebirge, wo basische Magmatite fehlen, kristallisierte ein High-K-Tonalit bei Drücken von ca. 0.7 GPa (Al-in-Hornblende-Barometer, magmatischer Epidot). Gerölle dieses Tonalits in einer untermiozänen (Helvet?) klastischeu Abfolge belegen eine schnelle Heraushebung des Tonalits durch dextrale Transtension im östlichsten Bereich des periadriatischen Lineaments. Eingeschaltet in die klastischen Sedimente sind andesitische bis dazitische Pyroklastika und Laven sowie diskordante dazitische Gänge, die alle der High-K-Serie angehören.Die chemische Variation innerhalb der Vulkanitserie von der Velenje-Rogatec-Linie läßt sich durch Fraktionierung der Einsprenglingsminerale Olivin, Plagioklas, Klinopyroxen, Orthopyroxen und Titanomagnetit erklären. Abnehmende Sr/Nd- und Sr/Y-Werte und zunehmende negative Eu-Anomalien mit steigendem SiO2 weisen auf eine bedeutende Plagioklas-Fraktionierung hin. Alle Vulkanite besitzen hohe Gehalte an schweren Seltenen Erden (chondritnormiert > 9.6) und geringe (Tb/Yb)n-Werte (1.29–1.08). Mit zunehmendem SiO2 nehmen die Gehalte an Yb(2.02 bis 4.30 ppm) und Y(18 bis 39 ppm) zu, während die Sc-Gehalte (32.5 bis 20.9 ppm) nur geringfügig abnehmen. Diese Charakteristika, zusammen mit geringen Hf/Lu- und Zr/Y-Werten (10.1–5.87 bzw. 5.7–3.6), schließen Granat als wesentliche, fraktionierende Phase aus. Da die (La/Yb)n-Verhältnisse (3.24–6.59) nicht mit SiO2 korrelieren und die chondritnormierten SeltenenErden-Muster keine nach oben konkaven Formen aufweisen, spielte die Fraktionierung von Amphibol keine wesentliche Rolle. Trotz geringer Rb/Cs-Werte ( 18) wird eine beträchtliche krustale Kontamination der Magmen angenommen. Für einen AFC-Prozeß sprechen negative Korrelationen von Nb/U(7.16–3.14) und Nb/Th(2.14–0.87) mit SiO2 (bei steigenden Nb-, U- und Th-Gehalten), geringe Hf/Ta-Werte (7.8–4.3) und teilweise auch geringe K/Rb- (340-71) und Zr/Rb-Verhältnisse (5.0–1.7).Die Magmatite des Pohorje-Gebirges weisen hohe U-Gehalte sowie geringe Nb/U-und Nb/Th-Verhältnisse auf (3.55–1.85 bzw. 1.27–0.64), die eine schwache negative Korrelation mit SiO2 zeigen. Zusammen mit hohen Ba/Nb-(56–93), Ba/La-(23-30) und Rb/Cs-Verhältnissen (19–56) sowie bereits publizierten 8O-Werten ( 9) weisen diese Eigenschaften auf einen beträchtlichen Anteil assimilierten Krustenmaterials in den Magmen hin. Hohe Sr-Gehalte (455–984 ppm) und relativ geringe negative Eu-Anomalien machen es unwahrscheinlich, daß während des AFC-Prozesses in der Unterkruste wesentliche Mengen an Plagioklas fraktioniert wurden. Obwohl die Gehalte an Sc (9.3–3.8 ppm) und Y (21–14 ppm) relativ gering sind, scheidet Granat aufgrund der geringen (Tb/Yb)n- Verhältnisse (1.67–1.14) als dominierende Fraktionierungsphase aus. Die Kombination von hohen (La/Yb)n- Verhältnissen (21.8–13.1) und geringen (Tb/Yb)n-Verhältnissen deutet eher auf Amphibol als wichtige, fraktionierende Phase hin.
With 9 Figures 相似文献
54.
Dr. E. Libowitzky 《Mineralogy and Petrology》1995,52(1-2):107-111
Summary Five polished samples of zoned magnetites from skarn deposits showed optical anisotropy effects under the ore microscope, though X-ray powder diffraction investigations indicated cubic magnetite. Using high magnification ore microscopy (oil immersion lenses, monochromatic light), extremely fine zones with slightly different reflectivity were observed. Scanning electron microscopy (SEM) of etched samples confirmed zones with a thickness between a few m and 100 nm. EDX analyses showed differences in the composition of these zones, ranging from almost pure magnetite to contents of CaO, MgO, A12O3, SiO2 up to 4 wt.% in total. Thus, the extremely thin, parallel zones of magnetite, with slightly different compositions and different optical constants (reflectivity, absorption, refraction), obviously lead to optical anisotropy due to form birefringence.
Optische anisotropie zonarer Magnetite aufgrund von formdoppelbrechung
Zusammenfassung Fünf Anschliffe von zonar gebauten Magnetiten aus Skarn-Lagerstätten zeigten unter dem Erzmikroskop optische Anisotropie-Erscheinungen, obwohl Röntgen-Pulverauf-nahmen kubischen Magnetit ergaben. Mittels hochauflösender Erzmikroskopie (Öl-Immersion, monochromatisches Licht) wurden extrem feine Zonierungen mit etwas unterschiedlichem Reflexionsvermögen beobachtet. Rasterelektronenmikroskopie (SEM) von angeätzten Proben bestätigte eine Zonendicke zwischen einigen Yin und 100 nm. EDX Analysen zeigten Unterschiede in der Zusammensetzung dieser Zonen, die von fast reinem Magnetit bis zu CaO-, MgO-, A12O3-, SiO2-Gehalten von insgesamt 4 Gew.% reichen. Offensichtlich fiihren die extrem diinnen, parallelen Zonierungen mit unterschiedlicher Zusammensetzung, und folglich unterschiedlichen optischen Konstanten (Reflexion, Absorption, Lichtbrechung) zu optischer Anisotropie durch Formdoppelbrechung.相似文献
55.
Dr. H. Volkert Dipl.-Met. M. Kurz Dipl.-Met. D. Majewski Dr. T. Prenosil Dr. A. Tafferner 《Meteorology and Atmospheric Physics》1992,48(1-4):179-191
Summary The forntal passage of 8 October 1987, which was extensively sampled during the first intense observation period of the German Front Experiment, is simulated by aid of three mesoscale models. The results are intercompared and held against the manually and objectively analysed observations of the meso and meso- scales, respectively. The orographic impact is studied by comparing model runs with full and cut-off Alps. Implications regarding similar efforts in the future conclude the paper.With 11 Figures 相似文献
56.
Much wildlife habitat is being destroyed by extractive resource industries in mountain environments. This article illustrates how mountain wildlife habitat was restored in a devastated area. A strip mine for coal on the east slopes of the Alberta Rockies, occupied during its operations by Rocky Mountain bighorn sheep (Ovis canadensis canadensis, Shaw 1803), was reclaimed as bighorn habitat. By considering the behaviour and habitat requirements of bighorns in conjunction with an operating coal mine and reclamation process, a large coal mining company has been able to reconstruct the mine site restoration to benefit mountain sheep. Although bighorn habitat requirements are well known, it was not until the animal and its requirements were studied against the backdrop of an operating coal mine that obvious recommendations regarding the maintenance and placement of high steep excavated rock faces were made and accepted by the government regulatory agencies. An open pit mine is a devastated landscape; trees, soil and overburden are removed to retrieve coal that may be up to 215 m underground. Overburden and soil are returned, but the disturbance compares to the barren landscapes left behind by glaciers. Contouring of the land, grading of overburden and soil, seeding with grass and legume mixtures and extensive fertilization are designed to speed plant colonization and soil development. By examining the bighorn's biological needs with respect to specific mining operations, a unique opportunity arose to employ McHarg's design with nature concept. This approach incorporates environmental and societal values into every aspect of development, and promotes the evaluation of the constraints and opportunities arising. The sheep numbered about 200. Their seasonal movements were similar to those found on native ranges. They used the reclaimed areas as winter range and for the mineral licks exposed during mining; in summer, the sheep moved to nearby alpine areas. Two thirds of all sightings were confined to 1.3 km2 of reclaimed grassland; its average productivity (4190 kg/ha) exceeded native ranges (1700 kg/ha). The body mass of female sheep in autumn equalled that of the largest in Alberta, but the skull dimensions were not larger than those of adjacent ranges. Infestation with lungworms was moderate. Lamb production and survival were high. Design criteria should be: feeding areas should be dry and lie within 300 m of escape terrain, which should have a slope of 40% and contain at least three benches. Rock piles should be placed on grazing areas. Mineral licks, a vital welfare factor, already existed within the high walls created by strip mining. 相似文献
57.
Dr. L. C. Hsu 《Mineralogy and Petrology》1992,47(1):87-101
Summary Bastnaesites of Ce and La and their OH-analogs were synthesized and their stability relations were determined atPf = 1 kbar andT = 400 to 900°C in a part of the system (Ce,La)-F-H-C-0. The initial fluid compositions were such that
and HF/(HF + H2O) ratios were 0 to 0.172. XRD and IR studies indicate that bastnaesites equilibrated in initial fluids low in HF are all F-enriched. The hydroxylbastnaesite-(La) is stable up to 810°C and the fluorbastnaesite-(La) is stable up to 860°C. Their condensed breakdown products are La2O2CO3 and LaOF, respectively. The stability of Ce bastnaesites is slightly
dependent. The hydroxylbastnaesite-(Ce) is stable up to 660°C at the
defined by the IQF buffer and up to 640°C by the MH buffer. The fluorbastnaesite-(Ce) is stable up to 800°C at the
defined by the IQF and up to 760°C by the MH buffer. The condensed breakdown product for the hydroxyl end-member is simply CeO2 but for the fluorine one is a combination of CeO2, CeF3, and CeOF. Factors, such as OH vs F,
, and bulk composition, that affect the stability of individual species are discussed. Petrogenic implications resulting from the present study include that bastnaesites can be stable from hydrothermal to magmatic conditions, that F-enriched species can form in an environment relatively low in F content, and that OH-species are rare and occur only in low-temperature environments essentially devoid of F.
With 8 Figures 相似文献
Synthese und Stabilität von Bastndsil in einem Teil des Systems (Ce,La)-F-H-C-O
Zusammenfassung Ce- und La-Bastnäsite, sowie deren OH-Analoga wurden synthetisiert und ihre Stabilitätsbeziehunger beiP f = 1 kbar undT = 400 bis 900°C wurden im System (Ce,La)F-H-C-O bestimmt. Die anfänglichen Flüssigkeitszusammensetzungen waren so, daß und die HF/(HF + H2O)-Verhältnisse 0–0.172 waren. Röntgenpulver- und Ultrarot-Untersuchungen zeigten, daß Bastnäsite, die mit anfänglich HF-armen Flüssigkeiten equilibriert wurden, alle an F angereichert sind. Hydroxilbastndsit-(La) ist bis 810°C und Fluorbastnäsit-(La) bis 860°C stabil. Ihre festen Zersetzungsprodukte sind La2O2O3, bzw. LaOF. Die Stabilität der Ce-Bastnäsite hängt etwas von ab. Hydroxilbastnäsit-(Ce) ist bei des Eisen-Quarz-Fayalit-Puffers bis 660°C stabil und mit Magnetit-Hämatit-Puffer bis 640°C. Das feste Zerfallsprodukt ist für das Hydroxil-Glied nur CeO2, für das Fluor-Glied eine Mischung aus CeO2, CeF3 und CeOF. Faktoren, welche die Stabilität der einzelnen Spezies beeinflussen, werden diskutiert, wie das Verhältnis OH zu F, und die Gesamtzusammensetzung. Petrogenetische Folgerungen aus der vorliegenden Studie schließen ein, daß Bastnäsite von hydrothermalen bis zu magmatischen Bedingungen stabil sein können, daß sich an F angereicherte Glieder in relativ F-armer Umgebung bilden können, und daß OH-Glieder selten sind und nur unter Bildungsbedingungen niedriger Temperatur und weitgehender Abwesenheit von F auftreten.
With 8 Figures 相似文献
58.
Dr. Izhak Schnell 《GeoJournal》1992,28(4):465-473
It seems that beyond differences among the drawings several generalisations may be made, relating to the ethno-spatial relations in Israeli Palestinian adolescents' perceptions, two years after the emergence of the uprising.
相似文献
| - Israeli Palestinian adolescents tend to adopt a nationalistic identity that to a large extent denies its Israeli civilian component, and thus tends to deny any shared identity with the Jewish sector. This is a shift from the Israeli Palestinians' political consensus which stresses the struggle for civilian and social equality. |
| - The Israeli Palestinian adolescents fully identify themselves with the Palestinians in the Occupied Territories, perceiving the uprising there as the major source of stimulation for the formation of a Palestinian identity. |
| - The PLO is perceived as the only political leadership which supports the Palestinians, including Israeli Palestinians, and offer a tangible sense of control over their destiny. |
| - The Palestinian identity crises (incuding the Israeli Palestinians) will be solved through the PLO military struggle for independence and peaceful compromise with the Jewish state. |
| - The elder adolescents, who have developed more sophisticated spatial abilities and have crystalised their collective identity, tend to attribute Palestinians and Jews with separate territorial bases, while the younger ones tend to ignore the territorial aspects of identity and inter-group relations. |
| - The compromise will lead to coexistence between two separate political identities which split the territory west of the Jordan river equally. |
| - The adolescents at the age of 13–14 represent strong awareness of the Palestinian national struggle and they clearly identify with a tendency to separate themselves from the Israeli state and join a Palestinian identity led by the PLO. If this is the milieu in which they form their identity for the future, one may conclude that the uprising succeeded in increasing unity and solidarity at least between the Israeli Palestinians and the Palestinians of the Occupied Territories around a more crystalised and determined national identity. |
59.
Kenneth Hewitt Dr. 《GeoJournal》1992,27(1):47-60
The review examines mountain land risks, especially those that involve sudden, more or less localized bouts of damage and disasters. Geographers' studies to date have mainly dealt with natural hazards, emphasizing those like avalanches, large landslides or natural dams that are uniquely associated with mountain environments. Such work is briefly reviewed. Earthquake risks are then singled out to help define and discuss problems faced by this work. They are shown to depend strongly upon aspects of mountain environments other than seismicity. Human vulnerability appears to be mainly dependent upon socioeconomic and habitat conditions which, although they determine seismic impacts, may and usually do develop independent of it. Moreover, these ingredients of risk are most closely associated with, or definitive of, the mountain people and areas. They are most strongly influenced by human agency, both in deciding who and what are exposed to risk, and in actually increasing or decreasing unfavorable responses to earthquakes. Recent earthquake disasters in the mountains also record how rapid changes in these social and habitat conditions, rather than seismicity, are increasing the scale and altering the forms of damage. These changes in turn, however, are largely dependent upon developments, initiatives and penetration from outside the mountains, and responses of mountain people more or less enforced by them. The importance of so-called highland-lowland interactions, is even more obvious in the most destructive of human hazards discussed, those of war and other armed violence. Mountain lands and peoples are shown to have been subject to recurrent warring, and a disproportionate share of the deployment of state violence in this century. Most of the casualties are resident civilians. They have been usually threatened by other uses of armed violence, including insurgency and counter-insurgency warfare and genocidal actions by state forces. Refugees and expellees from war zones have included great numbers of mountain folk. Another fast growing hazard of the late twentieth century, not unrelated to war and militarism, the international trafficking in and addiction plagues of hard drugs, has a unique relation to mountains. The South American growers of the coca leaf, and Southwest and Southeast Asian growers of the opium poppy are mountain farmers. Their participation is bringing a range of severe risks to their high valleys, as well as benefits. Finally the paper addresses the conceptual problems brought about by the compounding of determinist assumptions in both mountain land and hazards research. These include not only environmental determinist notions, or related Neo-Malthusian and Social Darwinist ideas, but the various historicist ones of assumed technological, economic and political stages of development. It is argued that such social constructions of the problem of hazards and disaster are dubious, and have become a major impediment to understanding and risk mitigation. Alternative frameworks require more attention to the regional, state, and global patterns of influence shaping risk in mountain lands, but also to the human ecology of mountain societies taking account of matters to which the expediences of technocratic expertise have made us blind. 相似文献
60.
Z. Borovec Dr. 《GeoJournal》1992,27(4):371-378
The amounts of fractions with size 63 m in the bottom sediments of the Bohemian part of the Labe (Elbe) river is variable. The grain-size distribution is poorly to very poorly sorted with a mean particle size from 5.1 to 12.2 m.The crystalline phase of recent sediments of the Labe river draining various types of parent rocks has a simple mineral composition, with predominant mica/illite, quartz, kaolinite and chlorite (±vermiculite ±smectite). There are also very small amounts of interstratification of 10 Å and 14 Å sheet silicates (11–13.6 Å). Small amounts of Na-rich plagioclase, K-feldspar and calcite have also been found; accessory amounts of amphibole, authigenic gypsum and pyrite are also present. Opal in diatomic tests is an omnipresent constituent. In the amorphic inorganic phase, hydrated oxides predominate, where Si >Al >Fe >Mn in a ratio of 64:28:22:1. The greatest amount of amorphous inorganic and organic phases were found in the 4 m fraction.A considerable part of the detrital material originates from soils formed on various igneous, metamorphic and sedimentary rocks, transported to the Labe by other rivers or directly by erosion in the immediate vicinity of the Labe river. 相似文献