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Pavle I. Premović 《Die Naturwissenschaften》1982,69(10):479-482
The Middle Precambrian chert of Gunflint formation contains an exceptionally high amount of bitumen free radicals. The Gunflint chert appears to be the oldest formation in which the presence of these radicals has been found. Their presence in this deposit constitutes evidence for the existence of primitive protovascular plants in the early Proterozoic environment of the Lake Superior Region of Canada. 相似文献
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Jeffrey I. Zink 《Die Naturwissenschaften》1981,68(10):507-512
Triboluminescence is the light emitted when mechanical energy is applied to a crystal. Many common substances such as sugar and copper sulfate are triboluminescent. The origin of the light and the mechanical, chemical, and crystallographic requirements of the phenomenon are described in this paper. 相似文献
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HLA typing of amniotic fluid cells has been used for the prenatal diagnosis of the HLA linked diseases congenital adrenal hyperplasia (21-OH-deficiency (21-OH-def) type) and complement C4 deficiency and it has also been used for the prenatal de termination of paternity. There are, however, technical difficulties in this test associated with the weak expression of some B locus antigens on amniotic fluid cells, and theoretical difficulties related to associations between particular HLA antigens and the 21-OH-def allele. Since certain HLA-B locus antigens are found in significantly increased frequencies among patients with 21-OH-def, there is a relatively high incidence of HLA-B homozygosity among the patients and over 40 percent of the parents of these patients share one or more HLA-B locus antigens. Results of some prenatal HLA typing tests may thus be difficult to interpret, and supplementary tests should be used whenever possible. HLA typing of amniotic cells is, however, the only available procedure for prenatal diagnosis of C4 deficiency and it is the best available procedure for prenatal determination of paternity. A modification of our original procedure allows HLA typing to be performed with increased numbers of HLA typing sera, and sera with optimum reactivity for amniotic fluid cells have now been selected for the definition of most of the more commonly expressed HLA antigens. Although amniotic fluid cells do not express DR antigens, amniotic fluid cells can be typed for the HLA-linked marker glyoxalase I (GLO) and this may be the informative for prenatal diagnosis in some cases. 相似文献
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