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81.
A systematic study for the optimization and implementation of high-performance capillary electrophoresis (HPCE) in conjunction with negative ion electrospray ionization-quadrupole time of flight-tandem mass spectrometry (ESI-QTOF-MS/MS) for the analysis of complex glycolipids is described. The performance of the capillary electrophoresis (CE) and off-line CE/ESI-QTOF-MS approach has been explored for screening a complex ganglioside mixture from bovine brain. All instrumental and solution parameters demonstrated to require special adjustment and to have the most substantial effect on the CE separation, abundance of product ions produced in a low-energy collision-induced dissociation (CID) process and their detection by MS/MS, when attempting to identify and sequence single ganglioside molecular species from CE eluted fractions. Upon optimization of the experimental parameters, an efficient methodology emerged providing the general basic requirements for combined CE/ESI-MS analysis of this type of complex glycoconjugate. 相似文献
82.
Summary From studies of aqueous solutions of dodecylammoniumnitrate an association mechanism has been proposed involving multiequilibrium. In the concentration range considered we can differentiate between two aspects: ranges of marked qualitative and quantitative changes and formation of differently structured surfactant species.
Zusammenfassung Aus der Untersuchung wäßriger Lösungen von Dodecylammoniumnitrat würde ein Assoziationsmechanismus abgeleitet, welcher ein Multiequilibrium beinhaltet. Im untersuchten Konzentrationsbereich können zwei Bereiche unterschieden werden: Bereiche mit ausgeprägten qualitativen und quantitativen Änderungen und Bereiche mit der Bildung von verschieden strukturierten oberflächenaktiven Spezies.相似文献
83.
Rudovsky J Hermann P Botta M Aime S Lukes I 《Chemical communications (Cambridge, England)》2005,(18):2390-2392
A marked increase of relaxivity has been observed upon rigidifying the internal frame of Gd-containing PAMAM dendrimers: the effect has been attained by either protonation of the dendrimer or by forming supramolecular adducts with cationic polyaminoacids. 相似文献
84.
Zusammenfassung Die Temperaturabhängigkeit der Viskosität im System LiNO3–H2O und im Temperaturbereich 20–70°C wird in der Gleichung =A expB/T=T
0 zusammengefaßt; aus der so erhaltenen Beziehung werden Rückschlüsse auf die Struktur der Lösungen gezogen.
Temperature dependence of the viscosity in the system LiNO3–H2O is expressed by =A expB/T-T 0 in the temperature range 20–70°C. Possible relations to structural changes in the solutions are considered.相似文献
85.
Reaction of [Nb(NMe(2))(5)] with 10 equiv of 2,6-Me(2)C(6)H(3)SH in toluene results in the formation of red crystals of [Nb(SC(6)H(3)Me(2)-2,6)(5)]. Crystal structure analysis of [Nb(SC(6)H(3)Me(2)-2,6)(5)] showed that the niobium center adopts a distorted trigonal bipyramidal geometry. Niobium disulfide, NbS(2), has been successfully prepared via a thio "sol-gel" process using [Nb(SC(6)H(3)Me(2)-2,6)(5)] as the metal source. In contrast, vapor phase thin-film studies revealed that [Nb(SC(6)H(3)Me(2)-2,6)(5)] functions as a single-source precursor to NbS films. 相似文献
86.
Summary Typical precipitation curves of various metal phosphates have been obtained using the turbidimetric technique. The following
systems have been investigated: Al(NO3)3-K3PO4, Al(NO3)3-KH2PO4, Al(NO3)3NaH2PO4, FeCl3-K3PO4, FeCl3-(NH4)2HPO4, FeCl3K2HPO4, FeCl3-KH2PO4, FeCl3-NaH2PO4, La(NO3)3K3PO4,La(NO3)3-K2HPO4,La(NO3)3-KH2PO4,La(NO3)3NaH2PO4 and Th(NO3)4-K2HPO4. Typical precipitation curves indicated concentration ranges of phosphate precipitation and of complex solubility.
Supported in part by the U.S. Army Research Office, Contract No. DA-ORD-10. 相似文献
Zusammenfassung Typische F?llungskurven verschiedener Metallphosphate, die mittels Trübungsmessungen erhalten wurden, wurden graphisch dargestellt. Die folgenden Systeme wurden untersucht: Al(NO3)3-K3PO4,Al(NO3)3KH2PO4, Al(NO3)3-NaH2PO4, FeCl3-K3PO4, FeCl3(NH4)2HPO4, FeCl3-K2HPO4, FeCl3-KH2PO4, FeCl3NaH2PO4, La(NO3)3-K3PO4, La(NO3)3-K2HPO4, La(NO3)3-KH2PO4, La(NO3)3-NaH2PO4 und Th(NO3)4K2HPO4. Typische F?llungskurven zeigten Konzentrationsgebiete, in welchen die Metallphosphate gef?llt werden, sowie Konzentrationen, die zur Komplexbildung führten.
Supported in part by the U.S. Army Research Office, Contract No. DA-ORD-10. 相似文献
87.
Graph theory is applied to the study of the dependence of total π-electron energy, π-electron charge distribution and free valency indices of conjugated hydrocarbons on molecular topology. It is shown that the number of loops in the molecular graph determines these quantities. 相似文献
88.
Tomislav Došlić 《Journal of mathematical chemistry》2007,41(3):217-229
A global forcing set in a simple connected graph G with a perfect matching is any subset S of E(G) such that the restriction of the characteristic function of perfect matchings of G on S is an injection. The number of edges in a global forcing set of the smallest cardinality is called the global forcing number
of G. In this paper we prove several results concerning global forcing sets and numbers of benzenoid graphs. In particular, we
prove that all catacondensed benzenoids and catafused coronoids with n hexagons have the global forcing number equal to n, and that for pericondensed benzenoids the global forcing number is always strictly smaller than the number of hexagons. 相似文献
89.
90.
Inspired by the concept of multivalency and in pursuit of ever more intricate artificial molecular machines, we investigated the strict self-assembly of a triply threaded two-component superbundle, starting from a tritopic receptor in which three benzo[24]crown-8 macrorings are fused onto a triphenylene core and a trifurcated trication wherein three bipyridinium units are linked 1,3,5 to a central benzenoid core. The result of the investigation was quite unexpected and surprising. It transpired that the rapid formation of a doubly threaded two-component complex was followed by an extremely slow conversion (a week at 253 K in CD3COCD3 to reach equilibrium) of this kinetically controlled product into a thermodynamically controlled one, namely a triply threaded two-component superbundle. This intriguing observation begs the question: are there instances in nature where multivalency is expressed as a kinetically controlled process, prior to an equilibrium state being reached, and if so, what are the biological implications, if any? 相似文献