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101.
102.
103.
Jayaprakash KN Peng CG Butler D Varghese JP Maier MA Rajeev KG Manoharan M 《Organic letters》2010,12(23):5410-5413
Novel non-nucleoside alkyne monomers compatible with oligonucleotide synthesis were designed, synthesized, and efficiently incorporated into RNA and RNA analogues during solid-phase synthesis. These modifications allowed site-specific conjugation of ligands to the RNA oligonucleotides through copper-assisted (CuAAC) and copper-free strain-promoted azide-alkyne cycloaddition (SPAAC) reactions. The SPAAC click reactions of cyclooctyne-oligonucleotides with various classes of azido-functionalized ligands in solution phase and on solid phase were efficient and quantitative and occurred under mild reaction conditions. The SPAAC reaction provides a method for the synthesis of oligonucleotide-ligand conjugates uncontaminated with copper ions. 相似文献
104.
105.
Kateřina Vítková Markéta Pechová Jan Petr Joanna Znaleziona Václav Ranc Vítězslav Maier Juraj Ševčík 《Central European Journal of Chemistry》2010,8(2):273-277
A method for the fast determination of yohimbine, a potent adrenoreceptor antagonist used for the treatment of sexual dysfunctions,
is proposed in this article. MEKC under basic and acidic conditions (sodium borate, pH 9.5 and sodium phosphate, pH 2.5) with
SDS was developed. The effect of the experimental parameters, e.g. pH, SDS concentration and injection time, on yohimbine
migration was also studied. Both methods were validated in terms of linearity, limits of detection and quantification, accuracy,
and precision using caffeine as an internal standard. The application for the determination of yohimbine in hand-made medicaments
is also investigated in this study.
相似文献
106.
Anke Schmauder Dipl.‐Chem. L. David Sibley Prof. Martin E. Maier Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(14):4328-4336
The first total synthesis of the cyclodepsipeptide chondramide A ( 2 b ) is described. This depsipeptide is composed of four subunits, namely L ‐alanine, N‐Me‐D ‐tryptophan, 3‐amino‐2‐methoxy‐propionic acid (β‐tyrosine derivative), and a 7‐hydroxy‐alkenoic acid. While the configuration of the stereogenic centers in the 7‐hydroxy‐alkenoic acid were known, the configuration of the tyrosine derivative required clarification and turned out to be (2S,3R) or (2L ,3L ), respectively. The synthesis of the 3‐amino‐2‐methoxy‐3‐arylpropanoic ester 20 b relied on an asymmetric dihydroxylation yielding diol ent‐ 15 a followed by a regioselective Mitsunobu substitution leading to 3‐azido‐2‐hydroxypropanoate 18 b . We could also show that the ester bond in the seco compound 26 b can be fashioned by a Mitsunobu esterification by using hydroxy ester (7S)‐ 7 and the tripeptide acid 25 b . This synthesis should allow for the preparation of various analogues. 相似文献
107.
Andrea Retzbach Joachim Marschall Marion Rahnke Lukas Otto Michaela Maier 《Journal of nanoparticle research》2011,13(12):6231-6244
In this article, we report data from an online questionnaire study with 587 respondents, representative for the adult U.S.
population in terms of age, gender, and level of education. The aim of this study was to assess how interest in science and
knowledge as well as beliefs about science are associated with risk and benefit perceptions of nanotechnology. The findings
suggest that the U.S. public is still rather unfamiliar with nanotechnology. Those who have some knowledge mainly have gotten
it from TV and the Internet. The content of current media reports is perceived as fairly positive. Knowledge of scientific
methods is unrelated to benefit and risk perceptions, at least when other predictors are controlled. In contrast, positive
beliefs about science (e.g., its impact on economy or health) and more sophisticated epistemological beliefs about the nature
of scientific knowledge are moderately linked to more positive perceptions of nanotechnology. The only exception is the perception
of scientific uncertainty: This is associated with less positive evaluations. Finally, higher engagement with science is associated
with higher risk perceptions. These findings show that laypersons who are engaged with science and who are aware of the inherent
uncertainty of scientific evidence might perceive nanotechnology in a somewhat more differentiated way, contrary to how it
is portrayed in the media today. 相似文献
108.
Takeshi Yoshizako Akihiko WadaKoji Uchida Shinji HaraMikio Igawa Hajime KitagakiStephan E. Maier 《Magnetic resonance imaging》2011,29(1):106-110
Purpose
This retrospective study was designed to evaluate the apparent diffusion coefficient (ADC) of line scan diffusion images (LSDI) in normal prostate and prostate cancer. Single-shot echo planner images (SS-EPI) were used for comparison.Materials and Methods
Twenty prostate tumors were examined by conventional MRI in 14 patients prior to radical prostatectomy. All patients were examined with a 1.5-T MR imager (Signa CV/i ver. 9.1 GE Medical System Milwaukee, WI, USA). Diffusion-weighted MR imaging (DWI) using LSDI was performed with a pelvic phased-array coil, with b values of 5 and 800 s/mm2. DWI using SS-EPI was performed with a body coil, with b values of 0 and 800 s/mm2. The ADCs of each sequence for 14 normal prostate and 20 prostate cancers were histopathologically assessed. Signal-to-noise ratio (SNR) on DWI was estimated and compared for each sequence.Results
The mean ADCs (±S.D.) of normal peripheral zones (PZ), transition zones (TZ) and cancer (in 10−3 mm2/s) that used LSDI were 1.42±0.12, 1.23±0.10 and 0.79±0.19, respectively. Those that used SS-EPI were 1.76±0.26, 1.38±0.20 and 1.05±0.27, respectively. Using unpaired t test (P<.05), we found a significant difference in each sequence between normal tissue (both PZ and TZ) and the cancer. Paired t test (P<.05) also registered a significant difference between LSDI and SS-EPI. Mean SNR for DWI using LSDI was 16.49±5.03, while the DWI using SS-EPI was 18.85±9.26. The difference between the SNR of each sequence was not statistically significant by paired t test.Conclusion
We found that ADCs using LSDI and SS-EPI showed similar tendencies in the same patients. However, in all regions, LSDI ADCs had smaller standard deviations than SS-EPI ADCs. 相似文献109.
M. V. Alfimov V. G. Plotnikov V. A. Smirnov V. Ya. Artyukhov G. V. Maier 《High Energy Chemistry》2014,48(3):174-179
A mechanism of energy transfer from highly excited triplet aromatic molecules has been developed, which involves a stage of formation of an exciplex between a highly excited energy-donor molecule and an unexcited energy-acceptor molecule. Interpretation of the experimental data on the shape and the intensity of triplet-triplet absorption bands and the energy transfer probability is presented. In this interpretation, the results of quantum-chemical calculations of the energies of highly excited triplet states of toluene and benzene molecules are used. 相似文献
110.
KM Varier AM Vinodkumar NVSV Prasad PV Madhusudhana Rao DL Sastry Lagy T Baby MC Radhakrishna NG Puttaswamy JJ Das P Sugathan N Madhavan AK Sinha DO Kataria 《Pramana》1999,53(3):529-533
Large enhancements have been observed in the sub-barrier fusion cross sections for Ti+Ni systems in our previous studies.
Coupled channel calculations incorporating couplings to 2+ and 3− states failed to explain these enhancements completely. A possibilty of transfer channels contributing to the residual enhancements
had been suggested. In order to investigate the role of relevant transfer channels, measurements of one- and two-nucleon transfer
were carried out for 46,48Ti+61Ni systems. The present paper gives the results of these studies. 相似文献