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排序方式: 共有214条查询结果,搜索用时 31 毫秒
121.
Björn C. Dollmann Dr. Andrei L. Kleschyov Dr. Vasily Sen Dr. Valery Golubev Prof. Dr. Laura M. Schreiber Prof. Dr. Hans W. Spiess Dr. Kerstin Münnemann Dr. Dariush Hinderberger 《Chemphyschem》2010,11(17):3656-3663
A potentially biocompatible class of spin‐labeled macromolecules, spin‐labeled (SL) heparins, and their use as nuclear magnetic resonance (NMR) signal enhancers are introduced. The signal enhancement is achieved through Overhauser‐type dynamic nuclear polarization (DNP). All presented SL‐heparins show high 1H DNP enhancement factors up to E=?110, which validates that effectively more than one hyperfine line can be saturated even for spin‐labeled polarizing agents. The parameters for the Overhauser‐type DNP are determined and discussed. A striking result is that for spin‐labeled heparins, the off‐resonant electron paramagnetic resonance (EPR) hyperfine lines contribute a non‐negligible part to the total saturation, even in the absence of Heisenberg spin exchange (HSE) and electron spin‐nuclear spin relaxation (T1ne). As a result, we conclude that one can optimize the use of, for example, biomacromolecules for DNP, for which only small sample amounts are available, by using heterogeneously distributed radicals attached to the molecule. 相似文献
122.
A novel one-pot isocyanide-based cascade four-component reaction between primary alkylamines, acetylenic esters, and alkyl isocyanides led to tetraalkyl 1-alkyl(aryl)-4-alkylamino-1,2-dihydropyridine-2,3,5,6-tetracarbxylates in good yields. 相似文献
123.
Issa Yavari Mehdi Sirouspour Sanaz Souri 《Monatshefte für Chemie / Chemical Monthly》2010,61(10):49-52
Abstract
A simple synthesis of N-alkylthiazoline-2-thiones by reaction of primary amines, carbon disulfide, and 2-chloro-1,3-dicarbonyl compounds in water is described. Proceeding without catalyst under one-pot conditions in high yields and with broad scope, this method high synthetic utility. 相似文献124.
Glycolurils insert as spacer elements in a capsule to create a new space with enhanced dimensions. 相似文献
125.
A zero-crossing first-derivative spectrophotometric method is applied for the simultaneous determination of naphazoline hydrochloride and antazoline phosphate in eye drops. The measurements were carried out at wavelengths of 225 and 252 nm for naphazoline hydrochloride and antazoline phosphate, respectively. The method was found to be linear (r2>0.999) in the range of 0.2-1 microg/ml for naphazoline hydrochloride in the presence of 5 microg/ml antazoline phosphate at 225 nm. The same linear correlation (r2>0.999) was obtained in the range of 1-10 microg/ml of antazoline phosphate in the presence of 0.5 microg/ml of naphazoline hydrochloride at 252 nm. The limit of determination was 0.2 microg/ml and 1 microg/ml for naphazoline hydrochloride and antazoline phosphate, respectively. The method was successfully used for simultaneous analysis of naphazoline hydrochloride and antazoline phosphate in eye drops without any interference from excipients and prior separation before analysis. 相似文献
126.
127.
Souri E Jalalizadeh H Kebriaee-Zadeh A Shekarchi M Dalvandi A 《Biomedical chromatography : BMC》2006,20(12):1309-1314
A new, simple, and reproducible method for determination of carboxylic acid metabolite of clopidogrel in human plasma has been developed. After liquid-liquid extraction in acidic medium with chloroform, samples were quantified on a Nova-pak C(8), 5 microm column using a mixture of 30 mM K(2)HPO(4)-THF-acetonitrile (pH = 3, 79:2:19, v/v/v) as mobile phase with UV detection at 220 nm. The flow rate was set at 0.9 mL/min. Ticlopidine was used as internal standard and the total run time of analysis was about 12 min. The method was linear over the range of 0.2-10 microg/mL of clopidogrel metabolite in plasma (r(2) > 0.999). The within-day and between-day precision values were in the range 1.0-4.8%. The limit of quantification of the method was 0.2 microg/mL. The method was successfully used to study the pharmacokinetics of clopidogrel in healthy volunteers. 相似文献
128.
Summary Protonation of the reactive intermediates produced in the reaction between alkyl(aryl) isocyanides and dialkyl acetylenedicarboxylates
by indan-1,3-dione leads to vinylnitrilium cations, which undergo carbon centered Michael type addition with the conjugate
base of the CH-acid to produce functionalized 5-oxo-4,5-dihydroindeno[1,2-b]pyrans. 相似文献
129.
Dariush Souri Ali Reza Khezripour Mehdi Molaei Masoud Karimipour 《Current Applied Physics》2017,17(1):41-46
The using of a reliable and accurate new method (called in literature as derivation of absorption spectrum fitting (DASF)) for evaluation of the optical band gap (Eg) and also the exact nature of charge carriers optical transitions, is investigated in ZnSe and ZnSe:Cu nanocrystals (NCs) synthesized by rapid microwave irradiation. This method can be performed by using the output of UV–Visible spectroscopy. The obtained Eg values are within the range of 2.985–3.261 eV, depending to the microwave irradiation time and Cu dopant percentage (decreasing trend with increasing of irradiation time and Cu content). The DASF-based obtained results for ZnSe and ZnSe:Cu nanoparticles, showed the more precise values of band gap, with the same trend of previously qualitative reported data on the same samples. Also, the direct gap nature of their optical transitions was justified. To perform the method, there is no any need to the concentration of solutions and merely one need the direct absorption or transmission spectra. In other word, DASF technique was employed on ZnSe NCs to confirm its validity and to avoid non-precise reports on optical band gap which can affect on the device optimizations based on these samples. Moreover, using the values of Eg, refractive index and dielectric constant of each sample were obtained at the absorption edge. Also, the width of the tailing states in the gap (Urbach energy: ETail) was estimated and were within the range of 0.049–0.122 eV, which their very small values in compare with Eg imply to the sharp valence and conduction band edges; it means the good crystallinity nature of the produced samples. 相似文献
130.