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排序方式: 共有371条查询结果,搜索用时 484 毫秒
1.
2.
Trace analysis of rapamycin in human blood by micellar electrokinetic chromatography 总被引:1,自引:0,他引:1
A capillary electrophoretic method with UV detection at 278 nm has been developed for analysis of the immunosuppressant rapamycin (sirolimus) in human blood at low microgram per liter levels. Separation has been achieved in an acidic carrier electrolyte containing sodium dodecylsulfate and 30% (v/v) acetonitrile. For sample clean-up and preconcentration, an off-line solid-phase extraction step using a silica-based reversed-phase material and an on-capillary focussing technique were employed. The latter allows the injection of increased sample volumes without excessive band broadening. Although this new method is less sensitive than existing liquid chromatographic procedures combined with mass spectrometry, it is fully suited to routine analysis of rapamycin in blood from patients treated with this drug. Last but not least the low costs make it an attractive alternative to established methods. 相似文献
3.
Urs P. Wild Hans J. Griesser Vo Dinh Tuan Jean F.M. Oth 《Chemical physics letters》1976,41(3):450-455
The emission spectra of the second excited singlet state of [18] annulene and of monofluoro [18] annulene (in a 3-methylpentane glass at 4 K) are reported. The large energy gap between the first and second excited singlet states inhibits fast internal conversion and favours the appearance of S2 → S0 emission. In addition, fluorescence from the S1 state can be observed in monofluoro [13] annulene by exciting into the S2 or directly into the S1 absorption. 相似文献
4.
U. Wannagat F. Vielberg H. Voß K. Hensen W. Sarholz 《Monatshefte für Chemie / Chemical Monthly》1969,100(4):1127-1132
The enthalpies of formation of the addition compounds F4Si(py)2, Cl4Si(py)2, Br4Si(py)2 and I4Si(py)4 have been measured calorimetrically by two different ways (see table 1). It was not possible to confirm enthalpy data published in7, 8. The sequence SiF44~SiBr4>SiI4(?) is proposed for the acceptor power of the silicon tetrahalides towards pyridine. 相似文献
5.
An application of a new standardization method for rapid activation mass analysis with registration of the strongly absorbed low-energy gamma radiation is described. This method makes it possible to avoid the use of the time-consuming and laborious method of Internal Standard. 相似文献
6.
Bhattacharyya S Fan L Vo L Labadie J 《Combinatorial chemistry & high throughput screening》2000,3(2):117-124
Amine libraries and their derivatives are important targets for high throughput synthesis because of their versatility as medicinal agents and agrochemicals. As a part of our efforts towards automated chemical library synthesis, a titanium(IV) isopropoxide mediated solution phase reductive amination protocol was successfully translated to automation on the Trident(TM) library synthesizer of Argonaut Technologies. An array of 24 secondary amines was prepared in high yield and purity from 4 primary amines and 6 carbonyl compounds. These secondary amines were further utilized in a split synthesis to generate libraries of ureas, amides and sulfonamides in solution phase on the Trident(TM). The automated runs included 192 reactions to synthesize 96 ureas in duplicate and 96 reactions to synthesize 48 amides and 48 sulfonamides. A number of polymer-assisted solution phase protocols were employed for parallel work-up and purification of the products in each step. 相似文献
7.
V. N. Michailidou B. Loppinet D. C. Vo O. Prucker J. Rühe G. Fytas 《Journal of polymer science. Part A, Polymer chemistry》2006,44(24):3590-3597
The dynamics of the concentration fluctuations in end-grafted polystyrene brushes in a theta solvent (cyclohexane) are probed by evanescent wave dynamic light scattering at different wavevectors q and temperatures. When the solvent quality changes from marginal to poor, the relaxation function C(q, t) exhibits strong effects as compared with the smooth variation of the brush density profile. From a single exponential above 50 °C, C(q, t) becomes a two-step decay function. The fast decay is still assigned to the cooperative diffusion albeit slower than in the good solvent regime whereas the slow nonexponential and nondiffusive process might relate to microsegragated and/or chain dynamics in the present polydisperse brush. The relaxation function of the present three brushes with different grafting density reveals similarities and disparities between wet brushes and semidilute polymer solutions. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3590–3597, 2006 相似文献
8.
Mildred M. Maguire Huang Do Son Kim Nguyen Chau Vo Douglas Smith Grant Koher Gregg Doutt Martyn C.R. Symons 《Journal of organometallic chemistry》1984,269(2):183-189
Exposure of (C5H5)2MO(CH3)2 and (C5H5)2W(CH3)2, prepared from the corresponding dichlorides, to 20Co γ-rays at 77 K gave H2C.CML3 carbene species characterised by their ESR spectra, together with a central feature possibly due to the parent cations. Dilute solutions in CD3OD gave features assigned to the parent anions which were converted on bleaching with visible light into methyl radicals, and H2C.ML3 radicals. From the magnitude of the 1H and 183W hyperfine coupling constants, it is deduced that the SOMO for H2C.WL3 radicals is strongly localised on carbon.Dilute solutions in aqueous sulphuric acid also gave species with A(2H) = 20 G, identified as the carbene derivatives, H2C.Ml3. These were formed on annealing, as signals assigned to HSO4 · radicals were lost. 相似文献
9.
A dynamic mathematical model is developed for production of Cerenol polyether from 1,3‐propanediol in a batch reactor system. The model accounts for polycondensation reactions and side reactions in the liquid phase and for mass transfer of volatile species to the vapor. Parameters are estimated using measured liquid‐phase concentrations of monomer, oligomers, water, and end groups as well as the mass and composition of condensate collected from the overhead condenser system. The proposed model uses novel probability factors to keep the model equations relatively simple while accounting for the complex influence of superacid catalyst on reaction rates. The model is a significant advance over previous Cerenol models because it better accounts for mass‐transfer rates and for the dynamic behavior of the condenser. In addition, the proposed model accounts for the inhibitory influence of water on polycondensation kinetics due to hydration of hydroxyl ends. The model equations and parameter estimates provide a substantial improvement in fit to the data, especially for long reaction times and high catalyst levels, resulting in a 97% reduction in the value of the weighted least squared objective function compared to equations and parameters from a previous model. 相似文献
10.
Oncogenic MicroRNAs Biogenesis as a Drug Target: Structure–Activity Relationship Studies on New Aminoglycoside Conjugates 下载免费PDF全文