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11.
The analytical performance of a glow discharge quadrupole mass spectrometer is demonstrated using sintered tungsten as an example. The inherent problem of molecular interferences in glow discharge mass Spectrometry has been considerably reduced using neon as a complementing discharge gas. Particular attention has been paid to time dependences. Analytical figures of merit are presented. 相似文献
12.
Dietmar Seyferth 《Journal of organometallic chemistry》1974,80(1):C18-C20
The preparation of dihapto {8-methylene)-1-naphthyl}bis(triphenyl-phosphine)platinum(II), involving an internal metallation reaction, is described. 相似文献
13.
The Diels—Alder reactions of α-pyrone with Me3SiCCSiMe3, Me3SiCCSiMe2H, Me2HSiCCSiMe2H, Me3GeCCGeMe3, Me3SiCCGeMe3, Me3SiCCSnMe3 and EtCCEt were examined. All except the first two acetylenes gave the expected 1,2-disubstituted benzene product, in line with results obtained previously with Me3SnCCSnMe3. The first two acetylenes, Me3SiCCSiMe3 and Me3SiCCSiMe2H, also yielded benzene products containing substantial amounts of the 1,3-disubstituted benzenes, as well as minor amounts of the 1,4-isomers. This formation of unexpected isomers during these reactions was shown to result from acid-catalyzed rearrangement of the initially formed 1,2-disubstituted products, 1,2-(Me3Si)2C6H4 and 1-Me3Si-2-Me2HSiC6H4. The acidic impurities arose from pyrolysis of the bromobenzene solvent used or were introduced as contaminants of the α-pyrone. Such isomerizations were inhibited by addition of small amounts of triethylamine. The fact that no rearrangement took place with the other acetylenes is due to the scavenging of acidic impurities which might cause isomerization by the starting acetylene and the benzene product via metal—carbon bond cleavage processes. 相似文献
14.
Mercuration of η5-cyclopentadienyl-η4-tetraphenylcyclobutadienecobalt, followed by transmetalation with n-butyllithium and reaction of the lithium derivative with benzophenone gave η4-Ph4C4Coη5-C5H4CPh2OH. Treatment of this alcohol produced the [η4-Ph4C4CoC5H4CP2]+ cation. This species reacted as a carbon electrophile with methanol, monomethylamine and N-methylpyrrole, as a cobalt electrophile with N,N-dimethylaniline and anisole. In the latter process the C5H4CPh2 ligand was displaced and the η6-arene-η4-tetraphenylcyclobutadienecobalt complexes were formed. Similar reactions with benzene, toluene and mesitylene proceeded only in the presence of aluminum chloride. The bonding in the cation is discussed on the basis of this chemistry and 13C NMR studies. 相似文献
15.
Dietmar Rahner Stefan Machill Heike Schlörb Kerstin Siury Matthias Kloss Waldfried Plieth 《Journal of Solid State Electrochemistry》1998,2(2):78-84
An overview is given of intercalation materials for both the negative and the positive electrodes of lithium batteries, including
the results of our own research. As well as lithium metal as a negative electrode, we consider insertion materials based on
aluminium alloys. In the case of the positive electrode metal-oxides based on manganese, nickel and cobalt are discussed.
Received: 27 May 1997 / Accepted: 30 July 1997 相似文献
16.
Scaffold based tissue engineering strategies use cells, biomolecules and a scaffold to promote the repair and regeneration of tissues. Although scaffold-based tissue engineering approaches are being actively developed, most are still experimental, and it is not yet clear what defines an ideal scaffold/cell construct. Solid free form fabrication (SFF) techniques can precisely control matrix architecture (size, shape, interconnectivity, branching, geometry and orientation). The SFF methods enable the fabrication of scaffolds with various designs and material compositions, thus providing a control of mechanical properties, biological effects and degradation kinetics. This paper reviews the application of micro-robotics and MEMS-based fabrication techniques for scaffold design and fabrication. It also presents a novel robotic technique to fabricate scaffold/cell constructs for tissue engineering by the assembly of microscopic building blocks. 相似文献
17.
Karsten Krohn Ishtiaq Ahmed Dietmar Gehle Mohammed Al Sahli 《Journal of carbohydrate chemistry》2013,32(2):64-77
Chiral building blocks for macrolides and related natural products are obtained from 1,6-anhydrosugars by conversion of the bicyclic acetals 2 or 12 into the open chain chiral 1,3-dithianes 6 and 13. Branched precursors can be obtained by opening of the ?erný epoxide 1 with the 1,3-dithiane anion to yield 7, followed by ring opening with 1,3-propanedithiol to the bis-1,3-dithiane 8. 相似文献
18.
19.
Dietmar K. Kennepohl Ronald G. Cavell 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):359-362
Abstract A series of neutral hexacoordinate λ6 phosphorus compounds of the general formula X4-n(CF3)nPN(R)C(C1)N(R) (n = 0, 1, 2, 3; R = cyclohexyl, isopropyl) has been prepared. The parent compounds are obtained by “insertion” of carbodiimide into the P-C1 bond of λ5-chlorophosphorane. Substituted pyridines also react readily with λ5 chloro and fluoro phosphoranes to form 2-methylamino, thio and oxopyridine chelates of the form X4P(Epy) (E = 0, NMe and S; X = F, Cl) in which the phosphorus achieves six coordination through acceptance of the pyridine nitrogen. Selected reactions and the fluxional behavior of the λ6 systems are discussed. 相似文献
20.