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91.
Machuca F de León SG Centeno A Fierro JL 《Journal of colloid and interface science》2001,237(2):290-293
The equilibrium parameters for the adsorption of Mo(VI) on gamma-Al(2)O(3) and of Co(II) and Pt(IV) on MoO(3)/gamma-Al(2)O(3) were determined. The adsorption isotherms were performed from aqueous solutions of the corresponding precursors on two different alumina supports. According to the classification given by Giles, L-type-shaped, subgroup 2, adsorption curves were found for the system Mo on gamma-Al(2)O(3), L-type, subgroup 1, for the Pt on MoO(3)/gamma-Al(2)O(3), and S-type for Co on the MoO(3)/gamma-Al(2)O(3) system. Numerical calculations were carried out for all the isotherms to find the equilibrium parameters. These constants are being used to model the development of Pt, Co, and Mo profiles on MoO(3)/gamma-Al(2)O(3) or gamma-Al(2)O(3) extrudates, respectively, which belong to the new generation of noble-metal-MoO(3)/gamma-Al(2)O(3)-supported catalysts to be used in oil-refining processes. Copyright 2001 Academic Press. 相似文献
92.
The cellular mechanism based on P-glycoprotein (PGP) for its drug pump function has become very important in multidrug resistance (MDR) research. A method has been established to characterize PGP on single K562 cell by coupling capillary electrophoresis with laser induced fluorescence detection. A permeable intact cell after the immunoassay binding with fluorescence labeling antibody was injected into the capillary and directly separated without lysis. It was found that once 5-10 optional cells were detected in batch, the PGP amount on this cell line could be outlined and calculated clearly. The PGP amount on K562 MDR cell line is 3.88 times higher than that on K562 sensitive cell line. These two cell lines with immunoassay binding were also analyzed by injection of multi-cells in order to improve the throughput. A resistance factor so called multidrug resistance multiple (MRM) was introduced to evaluate the MDR difference between cell lines. The MRM values of the cell line K562 measured by single cell analysis are well correlated with those by flow cytometry, which also prove the validity of our method in single cell analysis for the possibility of cancer diagnosis, pharmacokinetics and drug screening in future. 相似文献
93.
The association of a C3v-symmetrical calix[6]tris-amine with different concave tris-carboxylic acids of various degrees of flexibility has been explored by 1H NMR spectroscopy. In all cases, self-assembled structures directed by the selective inclusion of a neutral guest molecule were obtained, the more preorganized being stable in protic solvents. With a rigid C3-symmetrical cap, chiral guest recognition in the calixarene cavity resulted. A large tris-acidic partner gave a unique molecular ditopic receptor that is able to simultaneously accommodate two neutral molecules in two distinct hydrophobic cavities with different binding processes. 相似文献
94.
Perfluoromethyl Element Ligands. XXIX. Preparation and Spectroscopic Investigation of M(CO)4L2 Complexes (M ? Cr, Mo, W; L ? Me2PSMe, Me2PSeMe, (CF3)2PSMe, (CF3)2PSMe) The complexes M(CO)4L2 (see Inhaltsübersicht) have been prepared by the reaction of tetracarbonyl norbornadiene metal compounds M(CO)4NBD with L at room temperature or 35°C, respectively. The cis-complexes formed in the first step undergo rearrangement to trans-isomers at higher temperatures. New compounds have been characterized by analytical and spectroscopic (IR, NMR, MS) methods. 相似文献
95.
This review covers our extensive research activities in the area of fluorine containing phospha- and arsaalkenes as well as selenocarbonyls, which differ considerably in their properties and reactivities from their alkyl and aryl counterparts and thus contribute in a gratifying manner to the still growing field of unsaturated element-carbon compounds of 3rd and 4th row main group elements E. Of particular interest is the influence of the fluorine substituents and other small groups (OR, NR2) with either inductive and/or mesomeric effects on the polarity and reactivity of the EC bond. Addition reactions of proton acidic and hydridic polar HX reactants as well as [2+2], [3+2] and [4+2] cycloadditions have been thoroughly studied. The results obtained allow a classification of the EC systems within five different types, A to E, and prove a change from “normal” to “inverse” heteroalkenes in this sequence. The ligand properties of some derivatives have also been investigated in some detail. 相似文献
96.
R. Georges A. Delon F. Bylicki R. Jost A. Campargue A. Charvat M. Chenevier F. Stoeckel 《Chemical physics》1995,190(2-3):207-229
We have combined the high sensitivity of the ICLAS technique with the rotational cooling effect of a slit jet expansion in order to observe and to understand the visible and near infrared NO2 spectrum. By this way, an equivalent absorption pathlength of several kilometers through rotationally cooled molecules has been achieved. Due to the vibronic interaction between the two lowest electronic states,
2A1 and à 2B2, this spectrum is vibronically dense and complex. Moreover, the dense room temperature rotational structure is perturbed by additional rovibronic interactions. In contrast, the rotational analysis of our jet cooled spectrum is straightforward. The NO2 absorption spectrum is vanishing to the IR but, owing to the high sensitivity of the ICLAS technique, we have been able to record the NO2 spectrum down to 11200 cm−1 with a new Ti:sapphire ICLAS spectrometer. As a result 249 2B2 vibronic bands have been observed (175 cold bands and 74 hot bands) in the 11200–16150 cm−1 energy range. Due to the cooling effect of the slit jet we have reduced the rotational temperature down to about 12 K and at this temperature the K = 0 subbands are dominant. Consequently, we have analysed only the K = 0 manifold for N 7 of each vibronic band. The dynamical range of the band intensities is about one thousand. Due to the strong vibronic interaction between the
2A1 and à 2B2 electronic states, we observed not only the a1 vibrational levels of the à 2B2 state but also the b2 vibrational levels of the
2A1 state interacting with the previous ones. By comparison with the calculated density of states, we conclude that we have observed about 65% of the total number of 2B2 vibronic levels located in the studied range. However, there are more missing levels in the IR because of the weakness of the spectrum in this range. The correlation properties of this set of vibronic levels have been analysed calculating the power spectrum of the absorption stick spectrum which displays periodic motions: the dominant period, at 714 ± 20 cm−1, corresponds to the bending motion of the à 2B2 state. The other observed periods remain unassigned. In contrast the next neighbor spacing distribution (NNSD) shows a strong level repulsion, i.e. a manifestation of quantum chaos. These two observations, apparently contradictory, can be rationalized as follows: the short time dynamics, for t < 10−12 s, is “regular” while for longer times the dynamics becomes “chaotic”. We suggest that this behavior may be observed directly with a pump and probe fs laser experiment. 相似文献
97.
98.
Serum estradiol measurement by solid-phase chemiluminescence immunoassay and direct radioimmunoassay
Jozef de Boever Fortuna Kohen Marc Dhont Dirk Vandekerchkhove Georges van Maele 《Analytica chimica acta》1985
Estradiol017β is determined in serum extracts by solid-phase chemiluminescence immunoassay. The results are compared with those obtained from unextracted serum in routine conditions with a commercial radioimmunoassay (r.i.a.) kit. For the chemiluminescence procedure, a purified monoclonal antibody to estradiol-6-carboxymethyloxime/bovine serum albumin and the homologous chemiluminescent marker conjugate estradiol-6-carboxymethyloxime aminobutylethylisoluminol are used. Bound and free ligand are separated by washing and simple centrifugation. Results obtained by the chemiluminescence assay (y) and by r.i.a. (x) on 170 serum specimens from women during ovulation induction showed good correlation (y = 1.01x ? 16 with r = 0.95). The methods are similar in selectivity, detection limit (ca. 10 ng l?1) and precision (interassay relative standard deviation, 8–13%). 相似文献
99.
Jean BourguignonUlf Bremberg Georges DupasKristina Hallman Lars HagbergLaurent Hortala Vincent LevacherSerghey Lutsenko Emmanuel MacedoChristina Moberg Guy QuéguinerFredrik Rahm 《Tetrahedron》2003,59(48):9583-9589
Chiral pyridinooxazoline, quinolinooxazoline, bis(oxazolino)pyridine (pybox), and bisoxazoline (box) derivatives containing crown ether residues were prepared. Some of the ligands were assessed in substrate binding studies and in palladium catalyzed allylic alkylations. 相似文献
100.
Thierry Le Borgne Pierre Thury Michel Ephritikhine 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(1):m8-m9
The ligand 1,2,3,4‐tetramethyl‐5‐(2‐pyridyl)cyclopentadiene (cp*py) forms a dinuclear complex with UIV, i.e. di‐μ‐oxo‐bis{chloro(diethyl ether‐κO)[(η5,κN)‐1,2,3,4‐tetramethyl‐5‐(2‐pyridyl)cyclopentadienyl]uranium(IV)}, [U2Cl2O2(C14H16N)2(C4H10O)2], in which cp*py acts as a chelating ligand, being bound to the metal atom by the cyclopentadienyl unit and also by the N atom of the pyridyl ring. 相似文献