Amino acid diagenesis in the marine bivalve Arctica islandica Linné from northwest European sites: Only time and temperature?     

Hans Petter Sejrup  John-Erik Haugen 《第四纪科学杂志》1994,9(4):301-309

Collections of the molluscan species Arctica islandica from seven sites in Norway, Scotland and the North Sea, ranging in age from recent to Early Pleistocene, have been sampled for amino acid analyses. The shells were sampled in profiles through the valves at different distances from the umbo. In the fossil material a general trend of increasing degree of isoleucine (lle) epimerisation and decreasing amino acid concentrations were found going from the inner part of the valve to the outer. Although less pronounced, there is a similar trend from the central part of the valve to the margin. As the concentration of alloisoleucine (alle) remains nearly constant, the observed changes in alle/lle ratios are a result of variations in the amount of isoleucine. The amino acid composition is fairly uniform in recent shells and the observed gradients are established in mid-Holocene samples. Therefore, it is suggested that the gradients are established during rapid early degradation of the protein, possibly due to microbiological activity. Differences in alle/lle ratios observed in molluscs from sites of the same age and same thermal history could be explained by differences in the exposure to amino-acid-consuming microorganisms during the very early stage of diagenesis.  相似文献   

Kristallisationsschieferung oder Abbildungskristalloblastese?     

Hans Peter 《Mineralogy and Petrology》1948,1(2):188-190

Ohne Zusammenfassung  相似文献   

From Local Star Formation to Global Star Formation     

Hans Zinnecker 《Astrophysics and Space Science》2002,281(1-2):147-157

In this brief report we summarise the most important points raised in the course of a two-hour evening discussion session on the above topic, organised by the author. Major questions that were debated included the universality of the IMF, the history of the star formation rate in the solar neighorhood, the star formation efficiency in molecular clouds, and the role of triggered star formation. The issue of a threshold gas surface density for star formation to occur was also critically discussed. This revised version was published online in September 2006 with corrections to the Cover Date.  相似文献   

The introduction of radio nuclides over the atmosphere into the North Sea     

Dr. Hans Kautsky 《Ocean Dynamics》1983,36(4):145-155

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Observations and experiments on the population dynamics of epipelic diatoms from an estuarine mudflat     

Wim Admiraal  Harry Peletier  Hans Zomer 《Estuarine, Coastal and Shelf Science》1982,14(5):471-487

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Historical Climatology In Europe – The State Of The Art     

Rudolf?BráZdilEmail author  Christian?Pfister  Heinz?Wanner  Hans?Von?Storch  JüRg?Luterbacher 《Climatic change》2005,70(3):363-430

This paper discusses the state of European research in historical climatology. This field of science and an overview of its development are described in detail. Special attention is given to the documentary evidence used for data sources, including its drawbacks and advantages. Further, methods and significant results of historical-climatological research, mainly achieved since 1990, are presented. The main focus concentrates on data, methods, definitions of the “Medieval Warm Period” and the “Little Ice Age”, synoptic interpretation of past climates, climatic anomalies and natural disasters, and the vulnerability of economies and societies to climate as well as images and social representations of past weather and climate. The potential of historical climatology for climate modelling research is discussed briefly. Research perspectives in historical climatology are formulated with reference to data, methods, interdisciplinarity and impacts.  相似文献   

Association of spherical and ellipsoidal gravity coefficients of the Earth's potential     

Hans G. Walter 《Celestial Mechanics and Dynamical Astronomy》1970,2(3):389-397

A comparison is drawn between the expansion of the potential in spherical harmonics on the one hand and in ellipsoidal harmonics on the other, with the objective of associating the spherical and ellipsoidal gravity coefficients of the Earth's potential.For this purpose the properties of orthogonality of the Lamé functions of the first kind have been tailored to this subject of investigation and become instrumental in establishing the mathematical expressions which relate the two classes of gravity coefficients to each other. In deriving the elements of the transition matrices elliptic integrals have been encountered whose reduction to the three kinds of canonical elliptic integrals is discussed.Presented at the Conference on Celestial Mechanics, Oberwolfach, Germany, August 17–23, 1969.  相似文献   

A possibly direct measurement of coronal magnetic field strengths     

Hans Rosenberg 《Solar physics》1972,25(1):188-196

During a unique solar radio event on March 2, 1970, among very diverse features, a very regular pattern was observed in the solar radio spectrographic record between 220 and 320 MHz. The proposed explanation is emission by slightly relativistic electrons at the sum frequency of the plasma frequency ( 160 MHz) and the lower harmonics of the local gyrofrequency (n from 3 to 10), rather than emission at pure harmonics of the gyrofrequency (n from 15 to 20). The derived magnetic field strengths range from 3 to 8 G, and can be determined very accurately. From the simultaneously occurring pulsating structure in the type IV emission and the deduced magnetic field strength a typical size of the emitting region of 2–300 km is derived.  相似文献   

Sedimentary, tectonic, and sea-level controls on submarine fan and slope-apron turbidite systems     

Dorrik A. V. Stow  David G. Howell  C. Hans Nelson 《Geo-Marine Letters》1984,3(2-4):57-64

To help understand factors that influence submarine fan deposition, we outline some of the principal sedimentary, tectonic, and sea-level controls involved in deep-water sedimentation, give some data on the rates at which they operate, and evaluate their probable effects. Three depositional end-member systems, two submarine fan types (elongate and radial), and a third nonfan, slope-apron system result primarily from variations in sediment type and supply. Tectonic setting and local and global sea-level changes further modify the nature of fan growth, the distribution of facies, and the resulting vertical stratigraphic sequences. Margin setting represents fan and/or source area  相似文献   

The radiosonde intercomparison SONDEX spring 1981, Payerne     

Hans Richner  Peter D. Phillips 《Pure and Applied Geophysics》1982,120(5-6):852-1198

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