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排序方式: 共有1300条查询结果,搜索用时 15 毫秒
1.
Recently, we developed a convenient microfluidic droplet generation device based on vacuum‐driven fluid manipulation with a piezoelectric diaphragm micropump. In the present study built on our previous work, we investigate the influence of settings applied to the piezoelectric pump, such as peak‐to‐peak drive voltage (Vp‐p) and wave frequency, on droplet generation characteristics. Stepwise adjustments to the drive voltage in ±10‐Vp‐p increments over the range of 200?250 Vp‐p during droplet creation revealed that the droplet generation rate could be reproducibly controlled at a specific drive voltage. The droplet generation rate switched within <0.5 s after the input of a new voltage. Although the droplet generation rate depended on the drive voltage, this setting had almost no influence on droplet size. The frequency over the selected range (50?60 Hz) did not markedly influence the droplet generation rate or droplet size. We show that the current fluid manipulation system can be conveniently used for both droplet generation and for rapid droplet reading, which is required in many microfluidic‐based applications. 相似文献
2.
Mitsuki Yamashita Yuna Kawasumi Yuki Tachibana Dr. Shinnosuke Horiuchi Dr. Koji Yamamoto Prof. Tetsuro Murahashi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(5):1212-1216
Although small cyclic- and open-chain unsaturated hydrocarbon anions such as cyclopentadienide and open-chain pentadienide are used as the strongly electron-donating auxiliary ligands for metal complexes, more extended π-conjugated unsaturated hydrocarbon anions have rarely been used in coordination chemistry, despite their potential ability to serve as the multiply bridging π-ligands for metal clusters. This work reports isolation of metal chain clusters bearing the multi-dentate, open-chain extended unsaturated hydrocarbon anion ligands. The extended open-chain π-conjugated polyenyl ligands could effectively stabilize oxidized palladium chains, including an unprecedented [Pd4]4+ chain. 相似文献
3.
Joji Ohshita Ryosuke Taketsugu Yuki Nakahara Atsutaka Kunai 《Journal of organometallic chemistry》2004,689(20):3258-3264
Selective dehydrogenative coupling of di- and trihydrosilanes with alcohols catalyzed by PdCl2 or NiCl2 afforded alkoxyhydro- and dialkoxyhydrosilanes in good yield. Further treatment of the resulting alkoxyhydrosilanes with carbon tetrachloride or allyl bromide in the presence of the same catalyst led to the formation of alkoxychloro- and alkoxybromosilanes, respectively. Similar reactions of dialkoxyhydrosilanes with carbon tetrachloride afforded dialkoxychlorosilanes in good yield, although contamination of small amounts of trialkoxysilanes and alkoxydichlorosilanes was detected in the products. Selective substitution of the alkoxyhalosilanes with nucleophiles is also reported. 相似文献
4.
Hideyuki Yoshida Yuki Ohno Kenichiro Yoshikuni Kenichiro Todoroki Hitoshi Nohta Masatoshi Yamaguchi 《Analytical sciences》2003,19(2):317-319
A simple and sensitive fluorometric high-performance liquid chromatographic method was developed for the determination of midodrine in human plasma. After liquid-liquid extraction from plasma, the drug and 2-phenylglycinol (internal standard) were convened into the corresponding fluorescent derivatives by reaction with 3,4-dihydro-6,7-dimethoxy-4-methyl-3-oxoquinoxaline-2-carbonyl chloride, a fluorescence derivatization reagent for amines. The derivatives were separated within 30 min on a reversed-phase column using isocratic elution with acetonitrile-methanol-water (10:30:60, v/v) and were detected spectrofluorometrically at 485 nm with excitation at 400 nm. The detection limit for midodrine was 0.3 pmol (76 pg) per mL plasma at a signal-to-noise ratio of 3. 相似文献
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Akiko Saito Mana Emoto Akira Tanaka Yuki Doi Kazuaki Shoji Yoshiyuki Mizushina Hiroshi Ikawa Hiromi Yoshida Nobuyasu Matsuura Noriyuki Nakajima 《Tetrahedron》2004,60(52):12043-12049
A simple method for the synthesis of procyanidin B3 substituted with a galloyl group at the 3 and 3″ position is described. Condensation of a benzylated catechin-3-O-gallate electrophile with a nucleophile, catechin and catechin-3-O-gallate, proceeded smoothly and stereoselectively to afford the corresponding dimer gallates, procyanidin B3-3-O-gallate and procyanidin B3-3,3″-di-O-gallate, in good yields. Further, their antioxidant activities on UV-induced lipid peroxide formation, DPPH radical scavenging activity and inhibitory activity of DNA polymerase were also investigated. Among three procyanidin B3 congeners (procyanidin B3, 3-O-gallate and 3,3″-di-O-gallate), the 3,3″-di-O-gallate derivative showed the strongest antioxidant and radical scavenging activity. Interestingly, the 3-O-gallate derivative was the strongest inhibitor of mammalian DNA polymerase with IC50 value of 0.26 μM, although it showed the weakest antioxidant and radical scavenging activity. It became apparent that the presence of a galloyl group at the C-3 position in the proanthocyanidin oligomer was very important for biological activity, however, the antioxidant activity of these compounds was not parallel to the DNA polymerase inhibitory activity. 相似文献
8.
Mohri K Yokoyama K Komiya H Watanabe Y Yoshida Y Isobe K Tsuda Y 《Chemical & pharmaceutical bulletin》2003,51(5):502-507
Two new dioxopyrrolines (1-aryl-4-methoxycarbonyl-1H-pyrrole-2,3-dione 6 and the 5-methoxycarbonyl isomer 8) behaved as good dienophiles to some kind of 1,3-dienes examined. In most cases, the products were explained by the reaction where the largest lobe of HOMO of dienes reacted to the larger LUMO of dienophiles in an expected cis-endo manner. However, in the reactions of 8 with alkylbutadienes, piperylene and isoprene, abnormality in the reaction was observed, which was well explained by taking account of steric factors. 相似文献
9.
Phase diagram of a water/sucrose monododecanoate (SE)/hexanol system was determined at 30°C. Aqueous micellar, reverse micellar, normal hexagonal liquid crystalline, and lamellar liquid crystalline phases appear in the phase diagram. The change in interlayer spacing and interfacial section area of surfactant in the liquid crystalline phases was investigated by small-angle x-ray scattering. Upon addition of water, the section area and the radius of cylindrical aggregates are almost constant in a hexagonal liquid crystal, whereas the distance between each cylinder is separated on the water-SE axis. The interlayer spacing slightly decreases or is almost unchanged on the surfactant-hexanol axis, because alcohol molecules penetrate into the palisade of bilayers. Although the average section area decreases with increasing alcohol content, each section area of SE and alcohol molecules are kept constant. Since the interfacial section area of alcohol is less than the section area of hydrocarbon chain, the phase transition from lamellar liquid crystal to reverse micelle occurs in an alcohol-rich region. 相似文献
10.
An optical oxygen-sensing material based on the fluorescence intensity changes of pyrene-1-butyric acid (PBA) chemisorption film has been developed and characterised. The fluorescence intensity of PBA film decreased with increase of oxygen concentration. The I0/I100 value of PBA film is estimated to be 6.14±0.15 and large Stern-Volmer constant (KSV=0.028±0.13 Torr−1) is obtained. After irradiation for 24 h with 150 W tungsten lamp, little changes of oxygen-sensing properties were observed. These results indicate that PBA film is highly oxygen-sensitive and photostability device. The response times of the PBA chemisorption film were 10.0 s for switching from argon to oxygen, and 53.0 s for switching from oxygen to argon. Moreover, the optical sensor based on the PBA chemisorption film was applied to the measurement of oxygen concentration in aqueous solution. 相似文献