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排序方式: 共有105条查询结果,搜索用时 15 毫秒
1.
Stanislav Horník 《GeoJournal》1993,31(4):379-382
Some results of biogeographic research on meadows in the Dyje-Svratka basin in the Czech Republic. The paper shows one example of biogeographic inventory of natural ecosystems in an unflooded meadow in the Dyje-Svratka basin. It is part of the complex physio-geographic research of the Geographic Department of the Masaryk University in Brno aimed at gaining a basis for territorial interpretation of ecological regularities and territorial application of general ecological optimizing principles. A segment of biocenosis of Ulmi-fraxineta carpini has been analyzed (Zlatník 1956).The endeavour of Czech geographers to study geosystems of various dimensions completely gets in the limelight. In question is the understanding of mutual relationship of components of geosystems based on the exchange of mass and energy. There are two ways of studying them: spatial relations or approaches concentrated on processes. In contrast to the above unilateral concept, the endeavour to make the approaches compatible appears rarely. This complex view is made possible by geobiocenologically taken biogeography in papers of Zlatník and Rauer, their students and successors. This paper shows only one example of the results of biogeographic stock-taking of meadows in the Dyje-Svratka basin, indicating relations of eco- and geosystems which confirm the necessity of ecological orientation of the present biogeography and its potential contribution to ecology. 相似文献
2.
Stanislav V. Sinogeikin Jay D. Bass Bridget O'Neill Tibor Gasparik 《Physics and Chemistry of Minerals》1997,24(2):115-121
The adiabatic elastic moduli of polycrystalline En50Py50 and En80Py20 majorite-garnet solid solutions (where En=4MgSiO3, Py=Mg3Al2Si3O12) and the end-member En100 tetragonal majorite were determined at ambient conditions using Brillouin spectroscopy. The adiabatic bulk modulus, K, and
shear modulus, μ, of En50Py50 were found to be K=173.1 (20) and μ=92.3 (10) GPa, and are indistinguishable from those of the end-member pyrope, Py100. The moduli of the more majorite-rich samples are significantly lower and are virtually identical to each other (K=162.6(11)
and μ=85.7(7) for En80Py20; K=166(5) and μ=88(2) for En100). In combination with previously reported moduli for this system, we conclude that both K and μ are constant over the compositional
range from Py100 to a majorite content of about 70–80%, whereupon the moduli decrease substantially. For compositions ranging from En80Py20 to the end-member majorite, the moduli are also approximately independent of composition, but at a lower value. An alternative
model with a continuous decrease in moduli with increasing majorite content cannot be excluded, within the uncertainties of
existing measurements. The contrast in moduli between aluminous pyrope garnet and Al-free majorite are small compared with
the modulus changes accompanying the pyroxene – majorite phase transformation.
Received August 16, 1995 /Revised, accepted January 12, 1996 相似文献
3.
Stanislav Frančišković-Bilinski Mladen Juračić Darko Tibljaš 《Environmental Earth Sciences》2011,64(7):1755-1761
Surface sediments (fraction <63 μm) from the source to the mouth of the Rječina, short (18.3 km) karst allogenic river in
Croatia, which is an important source of drinking water, were studied to investigate their mineral (by XRD) and chemical (by
ICP-MS) composition to check possible anthropogenic influence at the lower course due to paper industry and mills, and in
the prodelta area from untreated municipal sewage and the large harbor of Rijeka town. In all analyzed sediment samples and
in the sandstone source, rock quartz is a major mineral, while feldspar and mica group minerals are less abundant. Chlorite
is a minor or trace mineral in all samples. Calcite and dolomite are abundant in the river prodelta, reflecting changes in
bedrock lithology from flysch to carbonates. In river sediments, Fe is the most abundantly analyzed element, while Ca is the
most abundant in prodelta sediments. Concentrations of Al, Mn, Ni, Cr, Co, La and Nd decrease downstream, while Mg, S, Na,
B, Pb, Zn, As, Sn, U, Mo, Hg and Ag have relatively higher concentration in prodelta sediments. The results are compared with
sediments of other rivers in the area: Raša, Rižana and Dragonja, as well as with those of the Rosandra Creek (Italy). Sediments
in the Raša River showed similar behavior as those in the Rječina, as the highest concentration of metals was found in the
restricted upper part of the estuary, characterized by rapid deposition of clay particles and terrestrial sedimentary organic
matter. The comparison also showed that the most contaminated were the sediments from the Rižana, followed by those from the
Rječina and Rosandra Creek, which had similar results. Among the studied elements, As was present in all sediment samples
at concentrations >6 ppm that might have the lowest toxic effects. At the lower Rječina and in prodelta sediments, Pb was
also present at slightly elevated concentrations (>31 ppm) that could cause such effects. Concentrations of Zn in the prodelta
correspond to those occurring in moderately polluted sediments (90–200 ppm). In the prodelta sediments, Hg is slightly below
toxicity threshold (1 ppm), while Ag is present at toxicity threshold (0.5 ppm) or close to it. Rječina River could act as
a good illustrative example for behavior of toxic metals in allogenic karstic rivers, in which accumulation of anthropogenically
introduced pollutants usually occurs in their estuaries, as a result of transport and deposition of fine particles. 相似文献
4.
Stanislav FRANCISKOVIC-BILINSKI Halka BILINSKI Delko BARISIC Nada HORVATINCIC Institute Ruder BoSkovi POB HR- Zagre Croati E-mail: francis@rudjer.irb.hrand YUAN Daoxian Institute of Karst Geology Guilin Guangxi China 《《地质学报》英文版》2003,77(2):267-275
The paper presents an analysis of characteristic karst tufa from Guangxi, China, which has not been studied before. A comparison with tufa from Dinaric Karst of Croatia is discussed in view of the C-type climate. The major mineral is calcite. Minor minerals are quartz and dolomite, depending on location. The content of calcium carbonate varies from 65% to 92%, and that of magnesium carbonate from 0.03% to 1.77%. Among other elements, the most abundant are Fe, from 0.02% to 1.50%, and Ti, from 0.15% to 0.27%. Many other trace elements (V, Cr, Mn, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Y, Zr, Hg and Pb) are also present. Specific activity of radionuclides 40K, 232Th, 137Cs, 226Ra and 238U varies from sample to sample. Concentration of U in tufa is close to that reported for sedimentary carbonate. Low concentration of 137Cs indicates that this part of the world was not exposed to nuclear explosions. The concentration of 226Ra is the highest in Mashan County. The ratio 238U/226Ra (0.21-0.71) in tufa from Mashan Co 相似文献
5.
The evolution of the Martian atmosphere and the potential existence of a past hydrosphere is a scientific issue of great interest in planetary research. Although the first missions to Mars had a focus on surface features and atmospheric properties, some of the missions (e.g., The Soviet Mars 2, 3 and 5) also carried instruments addressing the solar wind interaction with the Martian atmosphere and ionosphere and the potential existence of an intrinsic magnetic field on Mars. However, it took until 1989 before a spacecraft, Phobos-2, was able to carry out a more detailed investigation of the solar wind interaction with Mars. Phobos-2 gave valuable data on the Solar wind interaction with Mars during about 2 months of operations, leading to a better understanding of the solar wind impact on a weakly magnetized planet. However, Phobos-2 also raised a number of critical issues that has left science without adequate data since 1989.Investigations planned for Mars Express will cast new light on important aspects of the solar wind interaction with Mars. ASPERA-3 (Analyzer of Space Plasma and Energetic Atoms) on Mars Express will focus on the overall plasma outflow and monitor remotely the outflow and inflow of energetic neutral atoms produced by charge exchange processes. This report will discuss some of the unsolved issues about the solar wind interaction with Mars and how we plan to address these issues with Mars Express. 相似文献
6.
7.
This work tested the preferential use of fine (<63 μm) or bulk sediment (<2 mm) in environmental research of marine sediments in the Eastern Adriatic. Fine fraction sediment containing silt and clay (<63 μm), predominating in the studied area, was examined to evaluate past and present anthropogenic inputs and to test our hypothesis that investigation of bulk sediment should be preferred. Following aqua regia digestion, chemical analyses of 58 elements were performed by ICP/OES, ICP-MS and cold vapor AAS, and statistical analysis was performed. The concentrations of the majority of the analyzed elements increased with age of the sediment, except for Ag and Sn, which had higher concentrations in recent sediments. The previous main sources of metal contamination in Rijeka harbor were now abandoned municipal-sewage outflow and oil refinery, and continuing harbor activities and antifouling paint use. All activities except of antifouling paint use have been decreasing significantly. Anomalies of selected elements were determined by the box-plot method. More anomalies were found in the bulk sediment than in the fine fraction. Results of Q-modality clustering and factor analysis in the fine fraction almost correlate with that applied on bulk sediments. Thus, it can be said that the differences between the element distribution in the bulk and fine fraction are not statistically significant. Our conclusion is that analysis of bulk marine sediment gives a better insight into the state of pollution and supports previous recommendations to use bulk sediment as a chosen media for environmental studies. 相似文献
8.
Stanislav Brandejs 《Studia Geophysica et Geodaetica》1958,2(4):402-405
Резюме Нумерические прогнозы абсолютной топографии изобарической поверхности 500 мб, вычисленные по баротропному уравнению вихря
при помощи геострофического приближения, бывают, как правило, загрузены довольно значительными ошибками, вызванными с одной
стороны некоторыми недостатками модели, с другой стороны краевыми и начальными условиями решения. Очень неприятной и системтической
физической ошибкой является т. наз. ложныь антициклогенез, возникающий вследствие непоследовательного соблюдения бездивергентного
характера тока в эквивалентном баротропном уровне [4]. Этот ложный антициклогенез можно устранить тем, что при прогнозе абсолютной
топографии 500 мб применяем уравнения (16) или (22), в которые вместо
подставляем значенчия их из соотношению (17), (18) и (19), или из соотношения (23).
Anschrift: Praha II., Ke Karlovu 3. 相似文献
Anschrift: Praha II., Ke Karlovu 3. 相似文献
9.
10.
Grigory I. Dolgikh Mstislav N. Dubrov Stanislav G. Dolgikh Sergei N. Kovalev Vladimir V. Ovcharenko Egor A. Savvin Vladimir A. Chupin Vyacheslav A. Shvets Sergei V. Yakovenko 《Acta Geophysica》2006,54(2):187-197
The paper considers possibilities of applying laser strainmeters for the study of earthquake physics. One of laser strainmeters
is described. A high efficiency of using the laser strainmeters for the study of earthquakes and their precursors is shown.
In records of the spaced laser strainmeters, anomalous deformations propagating from the east to the west with the speed comparable
with that of migration of earthquakes were found. 相似文献