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11.
12.
Johannes Ueberberg 《manuscripta mathematica》1988,61(4):459-475
Zusammenfassung Die Hörmander-Klassen
1,
0
(0<1) von Pseudodifferentialoperatoren sind -Algebren. Insbesondere ist die Inverse eines inL(L
p
(
n
)) invertierbaren Pseudodifferentialoperators der Klasse
1,
0
selbst wieder ein Pseudodifferential-operator derselben Klasse.Der Beweis beruht auf den von R. Beals, R. R. Coifman, Y. Meyer und H. O. Cordes entwickelten Methoden zur Charakterisierung von Algebren von Pseudodifferentialoperatoren. 相似文献
13.
A new class of chiral dienophiles, 5-alkoxy-2(5H)-furanones, has been developed. Both enantiomers of 5-menthyloxy-2(5H)-ftiranone are readily available in enantiomerically pure form, starting from furfural and d- or l-menthol. Excellent diastereoselectivities (d.e. β99%) are obtained in thermal Diels-Alder reactions with several cyclic and acyclic dienes. The use of silyl dienol ethers has resulted in new routes to enantiomerically pure cyclohexanones in a highly regioselective manner. 相似文献
14.
15.
Gerhard Laus Johannes Schütz Herwig Schottenberger Max Andre Klaus Wurst Mariana Spetea Karl‐Hans Ongania AdrianG. Müller Helmut Schmidhammer 《Helvetica chimica acta》2003,86(10):3274-3280
The two diastereoisomeric ferrocenyl‐substituted orvinols 2 and 3 were prepared. The modified alkaloids are still able to interact with opioid receptors (see Table). The ferrocene moiety allows highly selective and sensitive electrochemical detection. The X‐ray crystal structure of the major isomer 2 was determined. The combination of a metallocene and a morphinan alkaloid holds promise for useful antitumor activity. 相似文献
16.
17.
The products of pyrolysis, at 400°C in vacuo (1 Pa), of poly(ethyleneterephthalate) (PET) and poly(butyleneterephthalate) (PBT) were studied. The products were identified by gas chromatography/mass spectrometry technique. The highly volatile products of PET contained acetaldehyde, benzene, toluene, styrene and ethylbenzene and in the case of PBT, butadiene, tetrahydrofuran, vinylcyclohexene and ethylbenzene were the major products. A qualitative analysis of the products of low volatility revealed that the main components were benzoic acid, terephthalic acid, monovinyl esters of terephthalic acid and higher oligomers in the case of PET, whereas benzoic acid, monobutenyl esters of terephthalic acid and higher oligomers were the main products from PBT. The results obtained were in good agreement with those obtained from pyrolysis experiments, carried out directly in the mass spectrometer. Mechanisms to explain the occurrence of the different products are proposed. 相似文献
18.
One-dimensional magnetism and crystal structure ofcatena-di-bromobis(3,5-dimethylpyridine)copper(II)
Johannes A. C. van Ooijen Jan Reedijk Eduard J. Sonneveld Jan W. Visser 《Transition Metal Chemistry》1979,4(5):305-307
Summary Crystals ofcatena-di--bromobis(3,5-dimethylpyridine)copper(II) are monoclinic, space group P21/a. The unit cell constants area=13.900(2),b=14.416(2),c=4.097(1) Å,=93.49(2)°, V=819.4 Å3 and Z=2. The structure was determined from powder data using a Guinier-Johansson focussing powder camera. The structure was solved using a simplex method for function minimization to a conventional R-value of 0.13.The structure consists of infinite linear chains parallel toc in which the copper coordination is distorted elongated octahedral. Cu-Br distances were found to be 2.449(7) and 3.286(7) Å, whereas the Cu-N bond length is 2.02(2) Å. All distances are in the range usually observed for this type of compounds.The antiferromagnetic superexchange interactions between adjacent CuII ions (J = –21 cm–1) has been compared with those observed in structural similar CuBr2L2 compounds. The differences in observed J-values are discussed briefly, in relation to the structural variations. It appears that very small changes in structural parameters strongly affect the magnetic exchange. 相似文献
19.
Zusammenfassung In Vorstehendem wurde zunächst die Ausführung der von einem von uns ausgearbeiteten Schwefelsäuretitration mittelst Benzidinchlorhydrats nochmals genau beschrieben, sodann wurden die Bedingungen festgestellt, unter denen verschiedene Schwefelsäuremengen am genauesten zu bestimmen waren. Es hat sich dabei herausgestellt, dass die Schwefelsäure bis zu 0,01g H2SO4 herunter nach der beshriebenen Methode auf 1–2 genau bestimmt werden kann. Die Anwendung der Methode auf verschiedene Fälle (Ammoniumsulfat, Alaun, Zinksulfat-heptahydrat, Mohr'sches Salz, Mangansulfat-tetrahydrat), wobei die Metalle in einigen Fällen vorher ausgefällt wurden, bestätigten die zuvor festgestellten Regeln; ausserdem wurde gezeigt, dass beim Ausfällen von Zink, Eisen und Mangan nach dem angegebenen Verfahren Schwefelsäure nicht mitgerissen wird. Die Zeit, welche eine derartige Bestimmung, auch wenn die beschriebenen Ausfällungen vorgenommen werden müssen, bei einiger Uebung erfordert, ist sehr kurz, weil alles Auswaschen und so weiter in Fortfall kommt, so dass auch hier ein Vortheil gegenüber dem gewichtsanalytischen Verfahren vorhanden ist. 相似文献
20.
Green Bis-(2-iminoisopropyl-thiophenolato)nickel(II) and other Similar NiII Complexes The compounds [NiII(iitp)2] 1 (iitp = 2-iminoisopropyl-thiophenolate), [Ni(imptp)2] · 2 CH3OH 2 , a dinuclear compound with an Ni? Ni distance of 276 pm, and [PPh4] · [NiII(imptp)(SCN)] 3 (imptp = 2-(2-iminopentane-4-on)-thiophenolate) have been prepared by the reaction of nickel(II)-acetate-tetrahydrate with 2-iminoisopropyl-thiophenole and 2-(2-iminopentane-4-on)-thiophenole in methanol, respectively. They have been characterized by single-crystal X-ray structure analysis and other physical methods. The redox behaviour of 1–3 has been studied in detail (chemically as well as by cyclovoltammetry and ESR spectroscopy). Particularly interesting are the electronic properties of 1 and its reduction with NaBH4 and the following reaction of the product with O2. The complexes are model compounds for some Ni-containing enzymes. For details of the crystal structure determination see “Inhaltsübersicht”. 相似文献