摘要:

AbstractIn classical times, black‐ and red‐figured vases were an important Greek export article, balancing payments resulting from grain import. This was especially true in Athens. The red pigment was always Fe2O3, and the black Fe3O4. A carefully chosen clay containing iron, which could be formed by hand with a simple potter's wheel, was used for thr vessel. The fired ceramic usually provided the red of the vessels. For the black painting, and for the occasionally used red painting (Intentional Red), a layer of finely elutriated clay was painted on. The vessel was fired between 800 and 900 °C, first under oxidizing conditions, then under reducing, and finally again under oxidizing conditions. From the reproductions of Adam Winter it may be concluded that an illitic clay was used for the black figure painting. During the reductive firing, the painted layer became impervious by sintering owing to the K2O content of the clay. A kaolinitic clay, poorer in K2O, served for the red painting. This clay remained porous on reduction and was reoxidized, like the ceramic of the vessel, in the second oxidation. For the terra sigillata of the Romans, the entire surface of the vessel was covered with a clay slip, which on firing under oxidizing conditions at higher temperatures, gave a hard surface, so that the vessel; could be used as table uten

ISSN:0570-0833    

DOI:10.1002/anie.196203411

出版商:Hüthig&Wepf Verlag    

年代:1962

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.196203511

出版商:Hüthig&Wepf Verlag    

年代:1962

数据来源: WILEY

摘要:

AbstractPrephenic acid is an intermediate in the biosynthesis of aromatic compounds. Its synthesis is made difficult by the fact that it is a cyclohexadienol which is easily aromatized by acids and bases. Experiments aimed at its synthesis have led to an as yet inseparable mixture of a little prephenic acid, epiprephenic acid and dihydroprephenic acid (as‐Ba‐salt). Comparison with model compounds indicated that the tertiary carboxyl group and the hydroxyl group are in cis relations

ISSN:0570-0833    

DOI:10.1002/anie.196203671

出版商:Hüthig&Wepf Verlag    

年代:1962

数据来源: WILEY

摘要:

AbstractTetracyclines are antibiotics used most freequently in the chemotherapy of infectious diseases. Numerous degradation and transformation products of natural teracyclines have been prepared and their biological properties tested. Furthermore, workers in several laboratories have been engaged in synthetizing tetracyclines or their biologically active degradation products. Some investigations carried out by the author and collaborators in this connection will be reported.

ISSN:0570-0833    

DOI:10.1002/anie.196203721

出版商:Hüthig&Wepf Verlag    

年代:1962

数据来源: WILEY

摘要:

AbstractThe results obtained in recent years from investigations into the mechanisms of electrophilic substitution reaction at sp3‐hybridized carbon atoms are reviewe

ISSN:0570-0833    

DOI:10.1002/anie.196203821

出版商:Hüthig&Wepf Verlag    

年代:1962

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.196203941

出版商:Hüthig&Wepf Verlag    

年代:1962

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.196203992

出版商:Hüthig&Wepf Verlag    

年代:1962

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.196204003

出版商:Hüthig&Wepf Verlag    

年代:1962

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.196204012

出版商:Hüthig&Wepf Verlag    

年代:1962

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.196204022

出版商:Hüthig&Wepf Verlag    

年代:1962

数据来源: WILEY