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排序方式: 共有1321条查询结果,搜索用时 15 毫秒
931.
Arakawa R Yamaguchi M Hotta H Osakai T Kimoto T 《Journal of the American Society for Mass Spectrometry》2004,15(8):1228-1236
On-line electrochemistry/electrospray ionization mass spectrometry (EC/ESI-MS) was developed using a microflow electrolytic cell. This technique was applied to electrochemical oxidation of caffeic acid (CAF) which is known to be a highly antioxidative agent. Effects of electrolytic potentials on ion intensities of product ions and on electrolytic currents were examined at different pHs. Dimer products were detected at electrolytic potentials of E = 0.7 V (vs. Ag/AgCl) and trimer products at 1.0 V at pH 9. Dimer products were distinguished from hydrogen-bonded complexes by MS/MS experiments. Hydrogen/deuterium exchange experiments determined the number of hydroxyl and carboxyl groups in the Dimers formed by electrolysis. The mechanism of oxidative polymerization of CAF is discussed with speculation as to the structure of the dimer product. 相似文献
932.
Kenta Itahashi Georg P. A. Berg Hiroyuki Fujioka Hans Geissel Ryugo S. Hayano Satoru Hirenzaki Natsumi Ikeno Naohito Inabe Satoshi Itoh Daisuke Kameda Toshiyuki Kubo Hiroaki Matsubara Shinichiro Michimasa Kenjiro Miki Hiroyuki Miya Masaki Nakamura Takahiro Nishi Shumpei Noji Shinsuke Ota Ken Suzuki Hiroyuki Takeda Koichi Todoroki Kyo Tsukada Tomohiro Uesaka Helmut Weick Koichi Yoshida 《Few-Body Systems》2013,54(7-10):1569-1572
We conducted an inclusive missing-mass spectroscopy of 122Sn (d, 3He) reaction near the π¯ emission threshold at an incident energy of T d = 250 MeV/nucleon. The experiment sets its goals to the research and development of the high precision spectroscopy of pionic atoms at the RI beam factory (RIBF) of RIKEN, which precedes a new project, pionic atom factory project (piAF), to observe pionic atoms systematically. Here, we report the preliminary results of the pilot experiment. 相似文献
933.
Yuri Matsuo Toshiyuki Oie Raita Goseki Takashi Ishizone Kenji Sugiyama Akira Hirao 《Macromolecular Symposia》2013,323(1):26-36
Five A-B-A′, A-C-A′, B-A-B′, C-A-C′, and C-B-C′ triblock terpolymers with block orders difficult to synthesize by sequential polymerization have been successfully synthesized by a new methodology combining living anionic polymers with a specially designed linking reaction using α-phenylacrylate as the reaction site. Here, A(A′), B(B′), and C(C′) represent groups of polymers (having chain-end anions with different nucleophilicities), which are only polymerizable from A(A′) to B(B′) to C(C′) via sequential polymerization. The corresponding polymers are polystyrene (A) and poly(α-methylstyrene) (A′), poly(2-vinylpyridine) (B) and poly(4-vinylpyridine) (B′) and polymers from methacrylate type monomers like poly(methyl methacrylate) (C), poly(tert-butyl methacrylate) (C′), poly(2-hydroxyethyl methacrylate) (C′), poly(2,3-dihydroxypropyl methacrylate) (C′), and poly(ferrocenylmethyl methacrylate) (C′). Furthermore, three synthetically difficult B-A-B, C-A-C, and C-B-C triblock copolymers with molecular asymmetry in both side blocks have also been synthesized by the developed methodology. All of the polymers thus synthesized are quite new triblock terpolymers and copolymers with well-defined structures, i.e., precisely controlled molecular weights, compositions and narrow molecular weight distributions (Mw/Mn ≤ 1.05). 相似文献
934.
Masaru Watanabe Takashi Matsushita Toshiyuki Miyake 《Polymer Degradation and Stability》2009,94(12):2157-2162
Polycarbonate (PC) could be completely decomposed into its monomer, bisphenol A (BPA) with high pressure (not atmospheric pressure) high temperature steam (573 K) in 5 min reaction time. The maximum yield of BPA was about 80 mol% based on the starting PC. PC decomposition at 573 K in liquid water phase near the saturated pressure for the comparison. For 30 min in reaction in liquid water at 573 K residual PC still remained and the BPA yield was about 50% as maximum. 相似文献
935.
Toshiyuki Itoh Manabu Kanbara Shino Nakajima Yusuke Sakuta Shuichi Hayase Motoi Kawatsura Takashi Kato Kazutoshi Miyazawa Hidemitsu Uno 《Journal of fluorine chemistry》2009,130(12):1157-1163
The synthesis of a novel spiro type gem-difluorocyclopropane building block, 1,1,7,7-tetrafluoro-2,8-bis(hydroxymethyl)dispiro[2.2.2.2]decane (1), has been accomplished in optically pure form using chemo-enzymatic reaction protocol. Various types of diesters or dialkyl ether were prepared from diol (+)-1 or (−)-1 in optically active form and their helical twisting power (HTP) was evaluated by addition of 1.0 wt% to a non-chiral nematic liquid crystal host. Although their HTP values were not significant, all compounds showed liquid crystal property with SmC* phase when they were dissolved (20 wt%) in achiral nematic host liquid crystal. 相似文献
936.
937.
Corporate scandals such as those at Tyco, Enron, and WorldCom have caused the decline of public trust in accounting and reporting practices. In response, US passed the Sarbanes Oxley Law (Sarbanes) in 2002, the most important corporate governance law since securities laws in 1930s. Section 302 of Sarbanes mandates corporations to ensure accurate financial disclosure and to take greater financial reporting and control responsibilities. Management is required to make an annual assertion regarding the design and effectiveness of company’s internal controls. Consequently, many internal auditing resources are stretched. The objective of this case study is to develop a multi-criteria decision making aid that can identify the most critical businesses units within a corporation. Using the aid, we can use efficiently and effectively the internal auditing resources. Internal audits determine if the accounting processes and systems are working as intended. It focuses on the reliability of the accounting data and evaluates business through financial, operational, and compliance review. It assesses the risk of asset loss, studies business processes, and identifies opportunities to improve efficiency and effectiveness. This study explores the potential of applying data envelopment analysis (DEA) and analytic hierarchy process (AHP) to determine the business units that need audit. Compared with conventional methods, the proposed combined model incorporates a much wider range of quantitative and qualitative criteria, and provides a more detailed and thorough study. The proposed evaluation framework is comprehensive and flexible and it shows great potential for internal audit prioritization and resource allocation. 相似文献
938.
I.M. Premachandra Gurmeet Singh Bhabra Toshiyuki Sueyoshi 《European Journal of Operational Research》2009
This paper proposes data envelopment analysis (DEA) as a quick-and-easy tool for assessing corporate bankruptcy. DEA is a non-parametric method that measures weight estimates (not parameter estimates) of a classification function for separating default and non-default firms. Using a recent sample of large corporate failures in the United States, we examine the capability of DEA in assessing corporate bankruptcy by comparing it with logistic regression (LR). We find that DEA outperforms LR in evaluating bankruptcy out-of-sample. This feature of DEA is appealing and has practical relevance for investors. Another advantage of DEA over LR is that it does not have assumptions associated with statistical and econometric methods. Furthermore, DEA does not need a large sample size for bankruptcy evaluation, usually required by such statistical and econometric approaches. The need for such a large sample size is a significant disadvantage to practitioners when investment decisions are made using small samples. DEA can bypass such a difficulty related to a sample size. Thus, DEA is a practically appealing method for bankruptcy assessment. 相似文献
939.
Salem Ben Saïd Toshiyuki Kobayashi Bent Ørsted 《Comptes Rendus Mathematique》2009,347(19-20):1119-1124
940.