A method for the analysis of the δ18O of inorganic phosphate extracted from soils with HCl     

F. Tamburini  S. M. Bernasconi  A. Angert  T. Weiner  E. Frossard 《European Journal of Soil Science》2010,61(6):1025-1032

The oxygen isotope composition of phosphate (δ¹⁸O‐PO₄) has successfully been used to study the biological cycling of phosphorus (P) in seawater and marine sediments. However, only a few studies have used this approach in soils. In order to analyse δ¹⁸O‐PO₄, phosphate must be extracted from the soil, purified and converted to silver phosphate (Ag₃PO₄). The published extraction methods, successfully applied to marine waters and sediments, lead to the precipitation of impure Ag₃PO₄when used with soils or organic‐rich samples. Here we present an improved purification protocol, designed for soils and other organic‐rich samples. After extraction with HCl, phosphate is purified with multiple mineral precipitations that do not require extreme pH adjustments of the solutions. We show that contaminant‐free Ag₃PO₄ can be produced from fertilizers and various soils with different chemical and physical characteristics. Our first isotopic results confirm that differences in P status and availability in soils are expressed in the δ¹⁸O‐PO₄ signal, indicating the potential of this isotopic tracer to understand P dynamics in soil systems.  相似文献   

The Hemostatic Activity of Amniotic Fluid     

Weiner AE  Reid DE  Roby CC 《Science (New York, N.Y.)》1949,110(2851):190-191

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J05Introduction of the concept of the 'Qualified Person' in the context of on-farm production and application of medicated feed in Switzerland     

S. HERRLI  B. GASSNER  O. FLECHTNER  X. SIDLER  A. LUGINBÜHL  W. KOCH  & R. ZWAHLEN 《Journal of veterinary pharmacology and therapeutics》2006,29(S1):309-309

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Environmental and chemical control of growth and flowering of Chamelaucium uncinatum Schauer     

Ruth Shillo  Amram Weiner  Abraham H. Halevy 《Scientia Horticulturae》1985,25(3):287-297

The main factor affecting floral initiation of Geraldton Wax-Flower (Chamelaucium uncinatum) is the photoperiod, while temperature is the major factor affecting flower development. Four weeks of short days (SD) are generally required for obtaining full flowering. The number of flowers produced per plant increases with increasing the number of SD. Under mild temperatures of $\text{20}\text{14°}\text{C}$ (day/night), plants initiated flowers even in long days (LD). However, fewer flowers were produced and on higher nodes as compared to SD plants. Chlormequat promoted flowering under prevailing summer conditions of high temperatures and LD. Under prevailing autumn conditions favourable for flower initiation, LD treatment or weekly sprays with gibberellic acid (GA) reduced the number of flowers per plant. Combined treatment of LD and GA reduced both the flowering percentage and the number of flowers per plant. Discontinuing the LD or the GA treatments caused a resumption of full flower initiation.  相似文献   

Pattern-oriented modeling of agent-based complex systems: lessons from ecology   总被引：6，自引：0，他引：6  

Grimm V  Revilla E  Berger U  Jeltsch F  Mooij WM  Railsback SF  Thulke HH  Weiner J  Wiegand T  DeAngelis DL 《Science (New York, N.Y.)》2005,310(5750):987-991

Agent-based complex systems are dynamic networks of many interacting agents; examples include ecosystems, financial markets, and cities. The search for general principles underlying the internal organization of such systems often uses bottom-up simulation models such as cellular automata and agent-based models. No general framework for designing, testing, and analyzing bottom-up models has yet been established, but recent advances in ecological modeling have come together in a general strategy we call pattern-oriented modeling. This strategy provides a unifying framework for decoding the internal organization of agent-based complex systems and may lead toward unifying algorithmic theories of the relation between adaptive behavior and system complexity.  相似文献   

Intercalation of sea urchin proteins in calcite: study of a crystalline composite material     

Berman A  Addadi L  Kvick A  Leiserowitz L  Nelson M  Weiner S 《Science (New York, N.Y.)》1990,250(4981):664-667

Sea urchin skeletal elements are composed of single crystals of calcite. Unlike their synthetic counterparts, these crystals do not have well-developed cleavage and are consequently much more resistant to fracture. This phenomenon is due in part to the presence of acidic glycoproteins occluded within the crystals. By means of x-ray diffraction with synchrotron radiation, it is shown that the presence of the protein in synthetic calcite only slightly decreases the coherence length but significantly increases the angular spread of perfect domains of the crystals. In biogenic calcite, the coherence length is 1/3 to 1/4 as much as that in synthetic calcite and the angular spread is 20 to 50 times as wide. It is proposed that the presence of macromolecules concentrated at mosaic boundaries that are oblique to deavage planes is responsible for the change in fracture properties. These results may be important in the material sciences, because of the unusual nature of this material, namely, a composite based on the controlled intercalation of macromolecules inside single-crystal lattices.  相似文献   

Japan's Nuclear Bomb Project     

Weiner C 《Science (New York, N.Y.)》1978,199(4330):730

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Global seminar held in new delhi     

Weiner D 《Science (New York, N.Y.)》1981,211(4482):568-569

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On the pathogenesis of duckling hepatitis     

P Kapp  F Karsai  I Weiner 《Acta veterinaria Academiae Scientiarum Hungaricae》1969,19(3):217-227

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From research evidence to context: the challenge of individualising care     

Weiner SJ 《Equine veterinary journal》2006,38(3):195-196

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