摘要:

AbstractDerivative spectrophotometry has gained increasing importance in the past two years and is currently experiencing vigorous development. Following and introduction the present article provides a review of this extremely effective method. In particular, the advantages ofhigher‐order derivative spectrophotometry (HODS method,n>2) are discussed on the basis of practical examples from a wide range of analytical fields. The results are achieved with the aid of a newly developed analog computer unit, whereby for the first time readily reproducible, low‐noise, on‐line spectra can be obtained up to the 7th order and even, in favorable cases, up to the 9th order. In practice it has proved valuable to work with spectra of the 3rd to 5th order; but even higher derivations could be profitable for the separation of strongly superposed signals or for “fingerpr

ISSN:0570-0833    

DOI:10.1002/anie.197807853

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

摘要:

AbstractIn recent years, aliphatic diazo compounds have proved to be more and more versatile as reagents in the preparative chemistry of organometallic complexes. As readily accessible compounds, they are not only suitable for the synthesis of known kinds of metal complexes but also open fresh routes to novel complex systems. The comparatively new field of diazoalkane complex chemistry exhibits numerous unexpected and novel reactions, and introduces interesting and promising aspects into the chemistry of carbonylmetal compounds.

ISSN:0570-0833    

DOI:10.1002/anie.197808001

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

摘要:

AbstractElectrostatic models of the chemical bond are based on the Virial Theorem and hold promise for providing a reliable and accurate method for predicting heats of formation of molecules and free radicals. The Principle of Alternating Polarity which states that those compounds are most stable in which atoms of opposite polarity are bonded is shown to be quantitatively described by electrostatic models. Current fixed partial‐charge models account for ΔH f0of hydrocarbon molecules and radicals. With inclusion of polarization effects, whose energies are small, they also account for the dipole moments in hydrocarbons. A brief account is given of a more general model with significant polarization interaction which is under development and which appears to be able to account for both ΔH f0and dipole moments of polar mo

ISSN:0570-0833    

DOI:10.1002/anie.197808121

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

摘要:

AbstractPolyethylene fibrids are small fibers having lengths of up to some millimeters, which are highly oriented and which have a morphology similar to that of cellulose fibers. The preparation of polyethylene fibrids is based on shear‐induced crystallization, a process in which the polyethylene crystallizes from solution under the influence of an elongated flow in the form of so‐called shish‐kebabs. Polymerization under shear conditions and the flash spinning of polyethylene solutions are the main processes for the preparation of PE fibrids. They may be hydrophilized by an additional process step.—Because of their cellulose‐like morphology, (hydrophilized) polyethylene fibrids have interesting properties,e.g.high adsorption capacity and the ability to form hydrogen bonds. In addition, the possibility of undertaking chemical reactions on the surface of the fibrids should be

ISSN:0570-0833    

DOI:10.1002/anie.197808201

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

摘要:

AbstractCooperation between the three scientistsLise Meitner, Otto Hahn, andFritz Strassmannin the study of the “transuranics” (1934—1938) prepared the way for the chemical identification of a first fission product of uranium byOtto HahnandFritz Strassmannat the end of 1938. Together with her nephewOtto Robert Frisch, she also gave the first theoretical interpretation of that experimental finding (barium instead of the expected radium) and suggested the inert gas krypton to be the second fission products, whichHahnandStrassmannsubsequently identified (besides xenon) among the products. But she was kept from direct participation in the experiments conducted at the Kaiser Wilhelm Institute for Chemistry at Berlin—and therefore from the unrestricted claim to being co‐discoverer of uranium fission—because she was an Austrian “Jewess”. Thus after the “annexation” of Austria by the German Reich, the Nazi racial laws also applied to her and precluded her continuing to work in Germany. She therefore emigrated illegallyviaHolland to Sweden in the middle of 1938. There she continued to work on problems of nuclear physics under less favorable conditions untill 1960. Work on radioactivity already started at Vienna had also brought her together withHahnat Berlin in 1907, and she continued the work at the Kaiser Wilhelm Institute studying α‐, β‐, and γ‐radiation and related nuclear processes. Not only because of her descent, but also because of her status of a woman in science, her fate was molded by the circumstances prevailing in Germany prior to World War II. On November 7, 1978Lise Meitnerwould have celebrated her hundredth birthday, reason enough for recalling her lot as a woman scientist in Germany against the background of her times, which should stand as a warning to us. To that end contemporary documents could be quoted which t

ISSN:0570-0833    

DOI:10.1002/anie.197808261

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197808421

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197808431

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197808441

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197808451

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197808461

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY