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101.
The antitumor agent (-)-rhazinilam was synthesized in three major steps, namely the pyrrole synthesis, selective C[bond]H bond activation, and direct macrolactam formation. The key step involved asymmetric C[bond]H bond functionalization (dehydrogenation) of the diethyl group segment in intermediate 6. This was achieved by the attachment of chiral platinum complexes to the proximal nitrogen atom. A high degree of selectivity (60-75% ee) was achieved via the use of oxazolinyl ketone chiral auxiliaries. 相似文献
102.
Merunka D Rakvin B 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,69(5):1331-1336
We consider the coupled dipole-proton system of hydrogen-bonded ferroelectric crystal with one defect dipole that is coupled more strongly with the protons than the original dipole. This defect dipole simulates the symmetry-breaking defects that are often introduced in the crystals as probes in the electron paramagnetic resonance (EPR) experiments. A particular attention is paid to the explanation of strong isotope effects that have been detected in the measurements of static and dynamic properties of the pure crystals and the symmetry-breaking defects. We suppose that the isotope effects are caused by the isotope-dependent tunneling energy and we analyze behavior of the system with and without the defect in two adiabatic approximations that correspond to the case when the protons tunnel faster than the dipoles oscillate and to the opposite case. These two approximations lead to the two models which predict different properties the pure crystals and the symmetry-breaking defects. 相似文献
103.
Supalkova V Beklova M Baloun J Singer C Sures B Adam V Huska D Pikula J Rauscherova L Havel L Zehnalek J Kizek R 《Bioelectrochemistry (Amsterdam, Netherlands)》2008,72(1):59-65
Within the context of application of platinum derivates based effective cytostatics, we can suppose that these risk metals can get into aquatic ecosystems where they can show biologic availability for food chain. In the present work we report on investigation of affecting of duckweed (Lemna minor) by various doses of cisplatin (0, 5, 10, 20, 40, 80 and 160 microM) for 4 days. The toxic influence of cisplatin was evaluated on the basis of growth inhibition expressed as number of leaves, growth rate, and total amount of biomass. The result value of 96hEC50, calculated from growth inhibition with comparison of growth rates, was 6.93 microM. Moreover we aimed on determination of cisplatin content using differential pulse voltammetry. The highest content of cisplatin (320 ng g(-1) of fresh weight) was determined in plants treated by 80 microM at the second day of treatment. Plants protect themselves against heavy metals by means of synthesis of cysteine-rich peptides such as glutathione and phytochelatins. Thus thiol determination in the treated plants by means of Brdicka reaction followed. The marked increase in thiol concentration detected is associated with defence reaction of the plant against stress caused by cisplatin. 相似文献
104.
Petr Chocholouš Kateřina Matoušová Dalibor Šatínský Lenka Kujovská Krčmová Hana Sklenářová 《Journal of separation science》2023,46(18):2300448
At the turn of the millennium, the monolithic columns invoked new chances in HPLC. Even more than their organic polymer-based siblings, the inorganic silica-based monoliths targeted the territory of classical fully porous particle-packed columns, promising many benefits. Based on the number of published articles, the monoliths attracted academics just in the first few years after their introduction to the market. Lately, as superficially porous particles and sub-2-micron fully porous particles dominated the market, they stayed in the focus of routine laboratories and those who really appreciated the high porosity of the monolithic bed. The monoliths' practical benefits cannot be easily traced in the literature when they gradually lose academics' interest. Nevertheless, after more than 20 years of our experience, we still favor silica monoliths for their low back pressure and longevity when analyzing samples of clinical, pharmaceutical, and environmental origin. At the same time, the high permeability of monoliths enabled the birth of sequential injection chromatography, the medium-pressure separation technique based on the flexible flow manifold. This minireview aims to check, discuss, and summarize the practical aspects of monolithic silica columns in HPLC and medium-pressure sequential injection chromatography (SIC) that may not be visible at first sight but are evident retrospectively. 相似文献
105.
We review high-performance liquid chromatography (HPLC) methods for the determination of two major statins used in clinical treatment – simvastatin and atorvastatin – in various fields of application, including bio-analytical assays, pharmaceutical assays and environmental applications.
Statin molecules are known to be susceptible to interconversion of the lactone and acidic forms, so it is necessary to consider this phenomenon during method development. We highlight liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) methods, as they have become a method of choice in bio-analytical and environmental applications. We compare the methods from the point of view of sensitivity. We discuss selection of the precursor ion for performing selected reaction monitoring (SRM) in MS detection and sample preparation. 相似文献
106.
Bell TD Jacob J Angeles-Izquierdo M Fron E Nolde F Hofkens J Müllen K De Schryver FC 《Chemical communications (Cambridge, England)》2005,(39):4973-4975
Two new peryleneimide end-capped polyphenylenes are shown to be deterministic single photon sources in PMMA films due to efficient annihilation between charge transfer states. 相似文献
107.
108.
Babić Sandra Horvat Alka J. M. Mutavdžić Dragana Čavić Dalibor Kaštelan-Macan Marija 《平面色谱法杂志一现代薄层色谱法》2007,20(2):95-99
JPC – Journal of Planar Chromatography – Modern TLC - Optimization of microwave-assisted extraction (MAE) as a method of sample preparation in thin-layer chromatographic (TLC) analysis... 相似文献
109.
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