[Without Title]     

Anne Marie de Grosbois 《Environmental Geology》2006,50(6):935-939

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Rapid colorimetric determination of phosphorus in geochemical survey samples     

D. Peachey  J.L. Roberts  Jane Scot-Baker 《Journal of Geochemical Exploration》1973,2(2):115-120

A colorimetric method for the determination of phosphorus in batches of geochemical survey samples is described. The powdered material is digested with a nitric-perchloric acid mixture, excess of acid is evaporated off and the residue is leached with water. Aliquots of the leachate are treated with vanadomolybdate reagent and the yellow phosphorus complex is extracted into isobutyl methyl ketone. The colour in the organic phase, which is stable for many days, is matched against a series of similarly prepared standards. Iron, other coloured ions, and titanium do not interfere. Standard deviations of ±0.02% about a mean value of 0.20% P₂ O₅ and ±0.4% about a mean of 11.6% P₂ O₅ were obtained. At least 40 powdered samples may be analysed per working day per person.  相似文献   

Reviews     

Daniel F. Merriam  R. A. Reyment  John W. Harbaugh  Eric C. Dahlberg  Marie Morisawa 《Mathematical Geology》1975,7(5-6):485-492

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Blocky craters: Implications about the lunar megaregolith     

T. W. Thompson  W. J. Roberts  W. K. Hartmann  R. W. Shorthill  S. H. Zisk 《Earth, Moon, and Planets》1979,21(3):319-342

Radar, infrared, and photogeologic properties of lunar craters have been studied to determine whether there is a systematic difference in blocky craters between the maria and terrae and whether this difference may be due to a deep megaregolith of pulverized material forming the terra surface, as opposed to a layer of semi-coherent basalt flows forming the mare surface. Some 1310 craters from about 4 to 100 km diameter have been catalogued as radar and/or infrared anomalies. In addition, a study of Apollo Orbital Photography confirmed that the radar and infrared anomalies are correlated with blocky rubble around the crater.Analysis of the radar and infrared data indicated systematic terra—mare differences. Fresh terra craters smaller than 12 km were less likely to be infrared and radar anomalies than comparable mare craters: but terra and mare craters larger than 12 km had similar infrared and radar signatures. Also, there are many terra craters which are radar bright but not infrared anomalies.Our interpretation of these data is that while the maria are rock layers (basaltic flow units) where craters eject boulder fields, the terrae are covered by relatively pulverized megaregolith at least 2 km deep, where craters eject less rocky rubble. Blocky rubble, either in the form of actual rocks or partly consolidated blocks, contributes to the radar and infrared signatures of the crater. However, aging by impacts rapidly destroys these effects, possibly through burial by secondary debris or by disintegration of the blocks themselves, especially in terra regions.PSI Contribution No. 110.  相似文献   

Clairaut's theory - integral form in terms of Hansen-Tisserand polynomials     

M. Marie  M. B. El-Shaarawy 《Earth, Moon, and Planets》1993,61(1):47-56

The fourth-order integral form of Clairaut theory have been derived in terms of Hansen-Tisserand (H-T) polynomials.  相似文献   

Western extension of the Iberian-European plate boundary during the Early Cenozoic (Pyrenean) convergence: A new model — Reply     

S. Grimaud  G. Boillot  B.J. Collette  A. Mauffret  P.R. Miles  D.B. Roberts 《Marine Geology》1983,53(3):238-239

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Use of the frozen flux approximation in the interpretation of archaeomagnetic and palaeomagnetic data     

David Gubbins  Neil Roberts 《Geophysical Journal International》1983,73(3):675-687

Summary. The frozen flux approximation of Roberts & Scott is a constraint on the core field that can be used to aid interpretation of the very sparse datasets that palaeomagnetism and archaeomagnetism provide. It gives bounds on the size of the components of the magnetic field at a point, of the Gauss coefficients, and, if valid over such long time periods, limits the shape of the field during transitions between normal and reversed polarities. The maximum intensity at a point, consistent with the present flux, is 281 μT or 4 times the maximum field observed today. The present dipole is about 50 per cent of its upper bound. Polarity reversal is impossible if the transition field is purely axisymmetric. None of the measurements we consider violate the frozen flux approximation.  相似文献   

Forest ecosystems: Concepts and management. Richard H. Waring and William H. Schlesinger. Academic Press,London, 340pp. ISBN 0-12-735441-7. Price: £21 (Soft Cover)     

J. Roberts 《水文研究》1987,1(2):221-224

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The long-period electromagnetic response of the Earth   总被引：1，自引：0，他引：1  

R. G. Roberts 《Geophysical Journal International》1984,78(2):547-572

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Wave propagation in a magnetic cylinder     

P. M. Edwin  B. Roberts 《Solar physics》1983,88(1-2):179-191

The nature of oscillations in a magnetic cylinder embedded in a magnetic environment is investigated. It is shown that the standard slender flux tube analysis of a kink mode in a cylinder excludes the possibility of a second mode, which arises under photospheric conditions. Under coronal conditions, two widely separated classes of oscillation can be freely sustained, one on an acoustic time-scale and the other on an Alfvénic time-scale. The acoustic-type oscillations are always present, but the much shorter period, Alfvénic-type, oscillations arise only in high density (strictly, low Alfvén velocity) loops. An application to waves in fibrils is also given, and suggests (following Wentzel, 1979) that they are fast kink waves propagating in a density enhancement.  相似文献