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A definition and classification of lectins (carbohydrate-binding (glyco)proteins) is given on the basis of new data and experimental results. Especially the biological role of bacterial, vertebrate and sponge lectins is discussed. The lectin-toxin combination offers an excellent model not only for studying adhesion to and penetration through the cell membrane, but also for hybridization with antibody fragments showing anti-tumor specificity.  相似文献   

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The eutrophication status of rivers is changed to a large degree by discharge of waste waters containing high amounts of phosphates from use of detergents. Sediments from the river Elbe in the port of Hamburg, and upstream from this town, and from some parts of the rivers Trave, Eider, and Schwentine are highly enriched with phosphorus. The phosphorus contents of up to 8300 ppm are about five to tenfold higher than the phosphorus contents of intensively fertilized soils. Phosphates accumulated in sediments are mainly bound as iron phosphates of different composition in a relatively labile binding form from which considerable amounts may be released to the water by various mobilization processes.  相似文献   

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This field is of special interest within the organometallic chemistry, which was and still is one of the most developing areas of chemistry for twenty years. The electronic structure around the atoms of germanium, tin, and lead favors both polar and radical reactions, and a plentiful coordination chemistry, too. Modern quantum chemistry arrived at these heavy atoms and allows better understanding also of low valent species, R2M. Chiral compounds with asymmetric Sn atoms, an object aimed at since 1905, have been prepared now, and dynamic stereochemistry has been studied. Industrial use of organotins has grown quickly and includes stabilization of plastics and plant and material protection as well. Biomethylation and environmental problems open this field both to biochemists and ecologists.  相似文献   

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