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排序方式: 共有1607条查询结果,搜索用时 31 毫秒
1.
Masamura Shinnosuke Iwamoto Tetsu Sugitani Yoshiki Konishi Keiji Hara Naoyuki 《Nonlinear dynamics》2020,99(4):3155-3168
Nonlinear Dynamics - The present study experimentally investigates amplitude death in delay-coupled double-scroll circuits with a time-varying network topology that randomly changes at a regular... 相似文献
2.
A simple high‐performance liquid chromatography for the determination of linezolid in human plasma and saliva 下载免费PDF全文
Shuuji Hara Masanobu Uchiyama Masami Yoshinari Taichi Matsumoto Shiro Jimi Atsushi Togawa Tohru Takata Yasushi Takamatsu 《Biomedical chromatography : BMC》2015,29(9):1428-1431
Linezolid is an antimicrobial agent for the treatment of multiresistant Gram‐positive infections. A practical high‐performance liquid chromatography method was developed for the determination of linezolid in human plasma and saliva. Linezolid and an internal standard (o‐ethoxybenzamide) were extracted from plasma and saliva with ethyl acetate and analyzed on a Capcell Pak C18 MG column with UV detection at 254 nm. The calibration curve was linear through the range 0.5–50 µg/mL using a 200 μL sample volume. The intra‐ and interday precisions were all <6.44% for plasma and 5.60% for saliva. The accuracies ranged from 98.8 to 110% for both matrices. The mean recoveries of linezolid were 80.8% for plasma and 79.0% for saliva. This method was used to determine the plasma and saliva concentrations of linezolid in healthy volunteers who were orally administered a 600 mg dose of linezolid. Our liquid–liquid extraction procedure is easy and requires a small volume of plasma or saliva (200 μL). This small volume can be advantageous in clinical pharmacokinetic studies, especially if children participate. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
3.
Nobuyuki Otozawa Rio Hamajima Masataka Yoshioka Raito Kato Arisa Tanaka Hiroto Fukuma Toshiki Terao Kei Manabe Syuji Fujii Yoshinobu Nakamura Atsushi Takahara Tomoyasu Hirai 《Journal of polymer science. Part A, Polymer chemistry》2020,58(14):1960-1964
This study investigates the effect of ionic liquids (ILs) on the anionic polymerization of methyl methacrylate (MMA). Polymethyl methacrylate (PMMA), an isotactic polymer, is prepared by anionic polymerization at a high reaction temperature with an IL that acts as both solvent and additive. The most plausible reaction mechanism is determined using 1H NMR and Fourier-transform infrared spectroscopy. The electrostatic interaction between MMA and the IL increases the apparent steric hindrance in MMA, resulting in the isotactic PMMA. 相似文献
4.
Mohammad Nasir Uddin Zainul Abedin Siddique Nobuyuki Mase Monir Uzzaman Wahhida Shumi 《应用有机金属化学》2019,33(6)
A number of oxotitanium(IV) complexes of the type TiOL with bis‐unsymmetric dibasic tetradentate Schiff base (LH2) containing ONNO donor atoms have been synthesized. Mono‐Schiff base (OPD‐HNP) was prepared by the condensation of 1:3 molar ratio of 2‐hydroxy‐1‐naphthaldehyde (HNP) with o‐phenylenediamine (OPD). Dibasic unsymmetric tetradentate diamine Schiff bases were prepared by the reaction of OPD‐HNP with 2‐hydroxyacetophenone, 2‐hydroxypropeophenone, benzoylacetone, acetylacetone and ethylacetoacetate. Further, titanylacetylacetonate was reacted with these ligands to obtain their metal complexes. On the basis of analytical and physiochemical data, the formation of complexes as TiOL was suggested having square pyramidal geometry. Quantum mechanical approach also confirmed this geometry. The assessment of the synthesized ligands and their complexes showed that some behave as good inhibitors of mycelial growth against selected phytopathogic fungi but weak inhibitors against some selected bacteria. A few of them also showed antioxidant properties. 相似文献
5.
Namita Panda Mieon Kim Nobuyuki Aoki Zeyi Zhou Takuya Shimosaka Youngdoo Kim Sangil Lee Dalho Kim 《Accreditation and quality assurance》2016,21(4):295-304
A validation study for primary formaldehyde gas standards was performed at three National Metrology Institutes: the Korea Research Institute of Standards and Science (KRISS), the National Metrology Institute of Japan (NMIJ) and the National Institute of Metrology of China (NIM). The studied materials had a nominal amount fraction of 2 μmol/mol formaldehyde in nitrogen balance and were prepared in 10-L aluminum cylinders by KRISS. The impurities in the materials were analyzed using a gas chromatograph/atomic emission detector and a Fourier-transform infrared spectrometer (FTIR). The stability of the materials was assessed for 1 year by KRISS using paraformaldehyde as a source for the primary standard gas and a cavity ring-down spectrometer (CRDS) instrument as the measurement method. The amount fraction of formaldehyde in the materials decreased linearly by 0.74 % each month. The studied materials that exhibited similar linear rates of decline were distributed to the participants. After the measurement was completed by the participants, the materials were returned to KRISS and the stability analysis based on the primary standard maintained at KRISS was repeated. NMIJ analyzed the materials using paraformaldehyde as the source of the primary standard of formaldehyde and FTIR analysis, whereas NIM used trioxane as the primary standard gas source and CRDS analysis. The results of the comparison revealed good agreement between the results and were within the expanded uncertainty of 2 % although each of them used different combinations of methods in the generation of primary gas standards and measurements. 相似文献
6.
Crystal Structure of the Isopropylzinc Alkoxide of Pyrimidyl Alkanol: Mechanistic Insights for Asymmetric Autocatalysis with Amplification of Enantiomeric Excess 下载免费PDF全文
Dr. Arimasa Matsumoto Takaaki Abe Atsushi Hara Takayuki Tobita Taisuke Sasagawa Prof. Dr. Tsuneomi Kawasaki Prof. Dr. Kenso Soai 《Angewandte Chemie (International ed. in English)》2015,54(50):15218-15221
Asymmetric amplification during self‐replication is a key feature that is used to explain the origin of homochirality. Asymmetric autocatalysis of pyrimidyl alkanol in the asymmetric addition of diisopropylzinc to pyrimidine‐5‐carbaldehyde is a unique example of this phenomenon. Crystallization of zinc alkoxides of this 5‐pyrimidyl alkanol and single‐crystal X‐ray diffraction analysis of the alkoxide crystals reveal the existence of tetramer or higher oligomer structures in this asymmetric autocatalytic system. 相似文献
7.
Hironao Nakayama Masako Nakahara Erina Matsugi Midori Soda Tomoka Hattori Koki Hara Ayuki Usami Chiaki Kusumoto Shigeki Higashiyama Kiyoyuki Kitaichi 《Molecules (Basel, Switzerland)》2021,26(1)
Ferulic Acid (FA) is a highly abundant phenolic phytochemical which is present in plant tissues. FA has biological effects on physiological and pathological processes due to its anti-apoptotic and anti-oxidative properties, however, the detailed mechanism(s) of function is poorly understood. We have identified FA as a molecule that inhibits apoptosis induced by hydrogen peroxide (H2O2) or actinomycin D (ActD) in rat pheochromocytoma, PC12 cell. We also found that FA reduces H2O2-induced reactive oxygen species (ROS) production in PC12 cell, thereby acting as an anti-oxidant. Then, we analyzed FA-mediated signaling responses in rat pheochromocytoma, PC12 cells using antibody arrays for phosphokinase and apoptosis related proteins. This FA signaling pathway in PC12 cells includes inactivation of pro-apoptotic proteins, SMAC/Diablo and Bad. In addition, FA attenuates the cell injury by H2O2 through the inhibition of phosphorylation of the extracellular signal-regulated kinase (ERK). Importantly, we find that FA restores expression levels of brain-derived neurotrophic factor (BDNF), a key neuroprotective effector, in H2O2-treated PC12 cells. As a possible mechanism, FA increases BDNF by regulating microRNA-10b expression following H2O2 stimulation. Taken together, FA has broad biological effects as a neuroprotective modulator to regulate the expression of phosphokinases, apoptosis-related proteins and microRNAs against oxidative stress in PC12 cells. 相似文献
8.
Phosphorescent Ruthenium Complexes with a Nitroimidazole Unit that Image Oxygen Fluctuation in Tumor Tissue 下载免费PDF全文
Dr. Aoi Son Atsushi Kawasaki Daiki Hara Dr. Takeo Ito Dr. Kazuhito Tanabe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(6):2527-2536
Understanding oxygen fluctuation in a cancerous tumor is important for effective treatment, especially during radiotherapy. In this paper, ruthenium complexes bearing a nitroimidazole group are shown to report the oxygen status in tumor tissue directly. The nitroimidazole group was known to be accumulated in hypoxic tumor tissues. On the other hand, the ruthenium complex showed strong phosphorescence around 600 nm. The emission of ruthenium is quenched instantaneously by molecular oxygen due to energy transfer between triplet states of oxygen and ruthenium complex, but the emission is then recovered by the removal of oxygen. Thus, we could observe oxygen fluctuation in tumor tissue in a real‐time manner by monitoring the phosphorescence of the ruthenium complex. The versatility of the probe is demonstrated by monitoring oxygen fluctuation in living cells and tumor tissue planted in mice. The ruthenium complex promptly penetrated plasma membrane and accumulated in cells to emit its oxygen‐dependent phosphorescence. In vivo experiments revealed that the oxygen level in tumor tissue seems to fluctuate at the sub‐minute timescale. 相似文献
9.
Ruthenium‐Immobilized Periodic Mesoporous Organosilica: Synthesis,Characterization, and Catalytic Application for Selective Oxidation of Alkanes 下载免费PDF全文
Nobuhiro Ishito Dr. Hirokazu Kobayashi Dr. Kiyotaka Nakajima Yoshifumi Maegawa Dr. Shinji Inagaki Dr. Kenji Hara Prof. Dr. Atsushi Fukuoka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(44):15564-15569
Periodic mesoporous organosilica (PMO) is a unique material that has a crystal‐like wall structure with coordination sites for metal complexes. A Ru complex, [RuCl2(CO)3]2, is successfully immobilized onto 2,2’‐bipyridine (BPy) units of PMO to form a single‐site catalyst, which has been confirmed by various physicochemical analyses. Using NaClO as an oxidant, the Ru‐immobilized PMO oxidizes the tertiary C?H bonds of adamantane to the corresponding alcohols at 57 times faster than the secondary C?H bonds, thereby exhibiting remarkably high regioselectivity. Moreover, the catalyst converts cis‐decalin to cis‐9‐decalol in a 63 % yield with complete retention of the substrate stereochemistry. The Ru catalyst can be separated by simple filtration and reused without loss of the original activity and selectivity for the oxidation reactions. 相似文献
10.
This paper proposes a delayed feedback control (DFC) based on the act-and-wait concept, which reduces the dynamics of DFC
systems to that of discrete-time systems. Based on this concept, a delayed feedback controller is designed for a prototype
two-dimensional oscillator using a simple systematic procedure. This control has two advantages: the feedback delay time can
be large and it can obtain deadbeat behavior. A numerical example using a double-scroll circuit model demonstrates these theoretical
results. 相似文献