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991.
992.
Helmut Fischer David Reindl Carsten Troll 《Journal of organometallic chemistry》1994,480(1-2):221-225
The successive reaction of chromium and tungsten hexacarbonyl, (CO)6M (M = Cr, W), with [N=C(Ph)R]− and [Et3O]BF4 yields the alkylideneamino(ethoxy)carbene complexes (CO)5M[C(OEt)N=C(Ph)R] (M = Cr (1), W (2); R = NMe2 (a), tBu (b)). Ethoxide abstraction from 1 and 2 affords 2-azoniaallenylidene complexes, {(CO)5M[CNC(Ph)R]}+BF4− (3/4). The complexes 3 and 4 are best described as resonance hybrids of several limiting structures. On the basis of the spectroscopic data of the complexes 3a and 4a the limiting structure of an iminium-substituted isocyanide complex dominates. 相似文献
993.
(R)-Malic, (S)-malic, (R)citramalic, (S)-citramalic, (2R,3S)-2-hydroxy-3-methyl-succinic and (2R,3S)-2,3-dimethyl-2-hydroxysuccinic acid were prepared on scales up to 25 mmol by stereospecific addition of water to different 2-butene-1,4-dioic acid derivatives catalyzed by resting cells of Clostridium formicoaceticum (Scheme 1). The (3R)-monodeuterio (R)- and (S)-malic acid as well as (R)- and (S)-citramalic acid were prepared using freeze-dried cells in 2H2O-buffer. The stereochemical purity of the products was in most cases ≥ 99%. 相似文献
994.
Wagner Y Sickmann A Meyer HE Daum G 《Journal of the American Society for Mass Spectrometry》2003,14(9):1003-1011
The analysis of macromolecular protein complexes is an important factor in understanding most cellular processes, e.g., protein transport into cell organells, signal transduction via biological membranes, apoptosis, energy metabolism, directed motion of cells, and cell division. These complexes are not only built of various numbers of different proteins but also of prosthetic groups and RNA molecules. To understand the role each protein plays in a complex, a complete analysis of all protein compounds is necessary. Therefore, several separation steps have to be coupled to mass spectrometry to identify the proteins. In this work, we describe the application of multidimensional liquid chromatography, SCX-RP-LC as well as SAX-RP-LC, coupled to electrospray ion trap mass spectrometry. Tryptic digested ribosomes were separated by ion exchange chromatography manually collected and prepared for reversed phase chromatography to analyze the peptides via nano-ESI mass spectrometry. The total numbers of identified proteins are compared in consideration of the separation method (SCX-RP versus SAX-RP). 相似文献
995.
996.
We investigated to what an extent mixed crystals of phosphates (arsenates) of Mn and Cd, [M5(HPO4)2(PO4)2 · 4 H2O], with Fe(II), Co, Ni, Zn and Cu can be formed. 相似文献
997.
998.
Stefan Peterli Regina Stumpf Marc Schweizer Urs Squin Helmut Mett Peter Traxler 《Helvetica chimica acta》1992,75(3):696-706
The syntheses and biological activities of some nitrostyrene derivatives of adenosine 5′-glutarates, a novel class of selective, bi-substrate-type inhibitors of the EGF receptor protein tyrosine kinase with IC50 values around 1 μM . Only marginal inhibition of the tyrosine kinases v-able and c-src and of the serine/threonine kinase PKC was observed. Compounds 8, 9, 11 , and 12 – lacking the adenosine moiety – were ten times less active than the most potent derivatives, whereas 17 – lacking the nitrostyryl part – showed no inhibitory activity at all. Most of the compounds showed potent antiproliferative activity against an EGF-dependent mouse keratinocyte cell line. 相似文献
999.
B3N3Me6Cr(CO)3 reacts with [AsPh4] [SnCl3] and [AsPh4] [GeCl3] in tetrahydrofuran to give [AsPh4]3[Cr(CO)3(SnCl3)3] and [AsPh4]3[Cr(CO)3(GeCl3)3], respectively. According to IR. and 13C-NMR.-data, the tricarbonylate anions possess a meridional configuration. The donor-acceptor properties of SnCl3? and GeCl3? in the anions [Cr(CO)3(ECl3)3]3? (E = Sn, Ge) are very similar. A similar synthesis of [AsPh4]3[Cr(CO)3(SnF3)3] was not successful. 相似文献
1000.
Helmut Spreitzer Petra Müller Gerhard Buchbauer 《Monatshefte für Chemie / Chemical Monthly》1990,121(11):963-970
Summary Some derivatives of 5,6-dihydro-2H-pyran-3-carboxaldehyde (7) and of its oxidation product 5,6-dihydro-2H-pyran-3-carboxylic acid (8) have been prepared. The aldehyde derivatives as well as the amides and esters of8 have been tested in an insecticidal/fungicidal/acaricidal screening programme. The methylester35 shows a distinct knock down effect against the fruit flyDrosophila melanogaster. 相似文献