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Andreas Mayer Stephan Neuenhofer 《Angewandte Chemie (International ed. in English)》1994,33(10):1044-1072
Chemical, chromatographic, or spectrometric methods are generally unsuitable for the detection of molecules in the nano and subnanogram region because of their low sensitivity. The radioimmunoassay (RIA) developed by Yalow and Berson in 1959 combined the high sensitivity of radioactively labeled substances with the high specificity of immunological reactions for the first time. In this way it was possible to detect quantitatively the tiniest traces of substances in the presence of an excess of other, in some cases, similar foreign substances without prior enrichment. Immunoassays have certainly developed to become the most valuable analytical tool of in vitro diagnostics and are today routinely employed for the detection of endogenous and exogenous substances (e.g. hormones, tumor-associated proteins, bacteria, viruses, toxins, drugs, etc). The many disadvantages of radioactivity such as the required handling licenses, disposal costs, precautions necessary to prevent risks to health, short shelf-life, and limited sensitivity soon led to the search for other nonradioactive labeling methods. Encouraged by the development of light measuring techniques and the commercial availability of highly sensitive apparatus, radioactive isotopes as labels are today being replaced increasingly by enzymes, fluorophores, or luminophores. Some of the new luminescent labels have, however, not only facilitated replacement of radioisotopes, but also a breakthrough into what has until now been unattainable levels of sensitivity. The following article reviews the methods of luminescent labeling and their applications mainly in the area of immunoassays. 相似文献
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Stephan H. Irsen Peter Kroll Richard Dronskowski Thomas E. Weirich Matthias Epple 《无机化学与普通化学杂志》2003,629(10):1751-1759
Tetrasulfur tetranitride, S4N4, reacts with elemental Cu within inert solvents to a black‐blue material of approximate composition Cu7S4N4 which is totally amorphous to X‐rays and which cannot be made crystalline by either thermal treatment or electron radiation. Cu7S4N4 explodes if heated above 234 °C or when subjected to mechanical shock to eventually yield copper(I) sulfide; this together with the characteristic infrared spectrum of Cu7S4N4 indicates the presence of molecular S4N4 units inside the amorphous phase. The metastable nature of Cu7S4N4 is also mirrored by electron microscopy which furthermore allows the structural characterization of its degradation products. Based on experimental EXAFS data offering characteristic Cu—N and Cu—S distances, a theoretical crystalline approximant of Cu7S4N4 was suggested and structurally optimized by density‐functional total‐energy calculations including periodic boundary conditions. This model incorporates a central S4N4 unit bonded to three shells of Cu atoms of different functionalities; in addition, a partial rupture of the S4N4 unit is likely to allow for a lowering of the total energy of the metastable phase. The latter observation supports the impossibility to make Cu7S4N4 crystallize using 4N4 crystallize using whatever kind of measures. 相似文献
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Ludwig Moser und Wilhelm Reif 《Mikrochimica acta》1930,8(1):215-218
Ohne Zusammenfassung 相似文献
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Ludwig Bieberbach 《Acta Mathematica》1926,48(3-4):319-327
Ohne Zusammenfassung 相似文献
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Ohne Zusammenfassung 相似文献
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Ludwig Bröcker 《manuscripta mathematica》1988,60(4):497-508
In this paper we show that two disjoint basic closed semialgebraic sets, defined over a real closed field R, can be separated by a polynomial, if one of them has dimension 2. Counterexamples are given in all higher dimensions. 相似文献
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