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991.
The effect of distance upon agricultural production should be as apparent among primitive subsistence agriculturalists as in market-oriented societies. This analysis of yield variations among the Basotho of southern Africa attempts to determine the frictional effect of distance. The results show that distance does not explain variations in yield even when other physical factors are held constant. Perhaps such variables as household characteristics, not included in the analysis, would provide a better explanation. 相似文献
992.
Richard J. Pike 《Icarus》1976,27(4):577-583
Inadvisable departures from tradition in naming newly mapped features on Mars, Mercury, and the Moon have been implemented and proposed since 1970. Functional need for place names also has become confused with cartographic convenience. Much of the resulting new nomenclature is neither unique, efficient, nor imaginative. The longstanding classical orientation in Solar System geography needs to be firmly reasserted. The Mädler scheme for designating smaller craters on the Moon should be retained and extended to the farside. Names of surface features on other bodies might best reflect the traditional connotations of planet and satellite names: for example, most crates on Mars would be named for mythical heroes and military personalities in ancient history, craters on Mercury might commemorate explorers or commercial luminaries, and features on Venus would bear the names of famous women. 相似文献
993.
Richard V. Tyson 《Marine and Petroleum Geology》1984,1(1):3-13
During the extension of Deep Sea Drilling Project (DSDP) Leg 76 a new and previously unpenetrated lithological unit composed mainly of claystones was cored above basalt basement at Site 534 in the Blake-Bahama Basin. The Callovian part of the new unit contains interbedded ‘black shales’ which were hitherto unexpected in this part of the section. This Paper presents a brief palynological examination of lithofacies-kerogen relationships in these sediments and shows that their organic content is almost entirely a function of the re-deposition of terrestial and marine organic matter versus the ambient redox conditions of the depositional environment. Allochthonous organic matter inputs are highest in the interbedded turbidites and decline progressively toward the pelagic black shales in which marine organic matter is comparatively well preserved. The significance of various kerogen and palynomorph indices are discussed. The study emphasizes the absolute necessity for sedimentologically-aware sampling in all palynological and geochemical work on lithologically heterogeneous sequences. 相似文献
994.
995.
Rigorous equations in compact symbolic matrix notation are introduced to transform coordinates and velocities between ITRF
frames and modern GPS-based geocentric geodetic datums. The theory is general but, after neglecting higher than second-order
terms, it is shown that the equations revert to the formulation currently applied in most major continental datums. We discuss
several examples: the North American Datum of 1983 (NAD83), the European Terrestrial Reference System of 1989 (ETRS89), the Geodetic Datum of Australia of 1994 (GDA94), and the South American Geocentric Reference System (SIRGAS).
Electronic Publication 相似文献
996.
997.
A multiple linear statistical model for estimating the mean maximum urban heat island 总被引:4,自引:0,他引:4
Summary ¶This study examines the spatial and quantitative influence of urban factors on the surface air temperature field of the medium-sized of Szeged, Hungary, using mobile measurements under different weather conditions in the periods of March 1999–February 2000 and April–October 2002. Efforts have been concentrated on the development of the urban heat island (UHI) in its peak development during the diurnal cycle. Tasks included: (1) determination of spatial distribution of mean maximum UHI intensity and some urban surface parameters (built-up and water surface ratios, sky view factor, building height) using the standard Kriging procedure, as well as (2) development of a statistical model in the so-called heating and non-heating seasons using the above mentioned parameters and their areal extensions. In both seasons the spatial distribution of the mean maximum UHI intensity fields had a concentric shape with some local irregularities. The intensity reaches more than 2.1°C (heating season) and 3.1°C (non-heating season) in the centre of the city. For both seasons statistical model equations were determined by means of stepwise multiple linear regression analysis. As the measured and calculated mean maximum UHI intensity patterns show, there is a clear connection between the spatial distribution of the urban thermal excess and the examined land-use parameters, so these parameters play an important role in the evolution of the strong UHI intensity field. From the above mentioned parameters the sky-view factor and the building height were the most determining factors which are in line with the urban surface energy balance. Therefore in the future, using our model it will be possible to predict mean maximum UHI intensity in other cities, which have land-use features similar to Szeged.Received September 26, 2002; revised February 25, 2003; accepted March 22, 2003
Published online July 30, 2003 相似文献
998.
Studia Geophysica et Geodaetica - 相似文献
999.
The solar eclipse on August 11, 1999, observed in the region covered by many geomagnetic observatories, has offered a unique opportunity to look for an effect of the eclipse on geomagnetic pulsations. The pulsation activity digital data have been taken from Budkov Observatory in the Czech Republic (in the X component only), from observatories in Germany (Niemegk, Fürstenfeldbruck, Bad Bergzabern), in Hungary (Nagycenk), and for comparison in South Africa (Hermanus, conjugate-point station), and in Finland (Sodankylä, far from the eclipse zone). At all these stations the field in all three component has been recorded. The pulsation amplitudes in the X component exhibit a long-term minimum near the time of the eclipse. Spectral analysis of selected short intervals confirmed this decrease and also revealed a decrease of the average pulsation period during the eclipse. Such a change in the amplitude or in the period was not observed outside of the eclipse interval or in other days. Investigation in some narrower frequency bands showed that the maximal decrease occurred in the 15–20 s band. All these changes can be found in records from all the stations near the eclipse totality belt, also in records at the conjugate-point station, where no eclipse occurred. No signature has been found in records at the station situated far from the eclipse zone. 相似文献
1000.
Studia Geophysica et Geodaetica - 相似文献