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1.
Ikuko Mori Miyuki Ukachi Kimiyo Nagano Hiroyasu Ito Jun Yoshinaga Masataka Nishikawa 《Analytical and bioanalytical chemistry》2010,397(2):463-470
A candidate environmental certified reference material (CRM) for the determination of multielements in tea leaves and materials
of similar matrix, NIES CRM No. 23 Tea Leaves II, has been developed and characterized by the National Institute for Environmental
Studies (NIES), Japan. The origin of the material was tea leaves, which were ground, sieved through a 106-μm mesh, homogenized,
and then subdivided into amber glass bottles. The results of homogeneity and stability tests indicated that the material was
sufficiently homogeneous and stable for use as a reference material. The property values of the material were statistically
determined based on chemical analyses by a network of laboratories using a wide range of methods. Sixteen laboratories participated
in the characterization, and nine certified values and five reference values were obtained. These property values of the candidate
CRM, which are expressed as mass fractions, were close to the median and/or mean values of the mass fractions of elements
in various tea products. The candidate CRM is appropriate for use in analytical quality control and in the evaluation of methods
used in the analysis of tea and materials of similar matrix. 相似文献
2.
When a mixture of o-alkynylaryl isocyanides and organic dichalcogenides such as diselenides or ditellurides was irradiated with light of wavelength over 300 or 400 nm, the intramolecular cyclization of the isocyanides took place to afford the corresponding 2,4-bischalcogenated quinolines selectively. The photochemical cyclization of 2-(phenylethynyl)phenyl isocyanide could also proceed in the presence of hydrogen transfer reagents such as tris(trimethylsilyl)silane, tributylgermyl hydride, alkanethiols, and benzeneselenol, providing the corresponding 3-phenylquinoline as the result of 2,4-dihydrogenation. 相似文献
3.
Harada T Hiraoka Y Kusukawa T Marutani Y Matsui S Nakatsugawa M Kanda K 《Organic letters》2003,5(26):5059-5062
Bis-BINOLs 7a-c in which two BINOL units are tethered by phenylenebis(ethynyl) groups react with titanium tetraisopropoxide (2 equiv) to form intramolecular dimeric titanium(IV) aggregates 2a-c. Of these, 2a,b with an o-phenylenebis(ethynyl) tether are stable in the presence of excess titanium tetraisopropoxide. Complex 2a exhibits a relatively high enantioselectivity in asymmetric addition of diethylzinc to an aldehyde. [structure: see text] 相似文献
4.
Iwao Ojima Mitsuru Nihonyanagi Tetsuo Kogure Miyoko Kumagai Shuji Horiuchi Kimiyo Nakatsugawa Yoichiro Nagai 《Journal of organometallic chemistry》1975,94(3):449-461
The hydrosilylation of various carbonyl compounds such as simple aldehydes, simple ketones, α,β-unsaturated carbonyl compounds, α-diketones, acyl cyanides and ketones having an electron-withdrawing group on the α-carbon using tris(triphenylphosphine)chlororhodium as a catalyst is described. Solvolysis of these silyl ethers and silyl enol ethers afforded the corresponding reduced products. The hydrosilylation of α,β-unsaturated carbonyl compounds was found to proceed by 1,4-addition. An oxidative adduct of triethylsilane to the rhodium-(I) complex was obtained as a reaction intermediate. The structure of the adduct was discussed on the basis of its IR and far-IR spectra. 相似文献
5.
6.
Hwang SH Hicks K Ahn JK Nakano T Ahn DS Chang WC Chen JY Daté S Ejiri H Fujimura H Fujiwara M Fukui S Gohn W Hotta T Imai K Ishikawa T Joo K Kato Y Kohri H Kon Y Lee HS Maeda Y Miyabe M Mibe T Morino Y Muramatsu N Nakatsugawa Y Niiyama M Noumi H Oh Y Ohashi Y Ohta T Oka M Parker J Rangacharyulu C Ryu SY Sawada T Sugaya Y Sumihama M Tsunemi T Uchida M Ungaro M Yosoi M;LEPS Collaboration 《Physical review letters》2012,108(9):092001
The exclusive reaction γp→K(+)π(-)Σ(+) was measured for the first time using linearly polarized photons at beam energies from 1.85 to 2.96 GeV. Angular distributions in the rest frame of the K(+)π(-) system were fitted to extract spin-density matrix elements of the K(*0) decay. The measured parity spin asymmetry shows that natural-parity exchange is dominant in this reaction. This result clearly indicates the need for t-channel exchange of the κ(800) scalar meson. 相似文献
7.
Salvileucalin B, a novel diterpenoid with an unprecedented rearranged neoclerodane skeleton from Salvia leucantha Cav 总被引:1,自引:0,他引:1
Aoyagi Y Yamazaki A Nakatsugawa C Fukaya H Takeya K Kawauchi S Izumi H 《Organic letters》2008,10(20):4429-4432
Salvileucalin B (2), having an unprecedented rearranged neoclerodane skeleton, was isolated from the aerial parts of Salvia leucantha Cav. (Labiatae) along with salvileucalin A (1). The absolute structures were elucidated by spectroscopic analysis, X-ray crystallographic analysis, and vibrational circular dichroism. Compound 2 represents a novel neoclerodane, characterized by a tricyclo[3.2.1.0 (2,7)]octane substructure incorporating the exocyclic C-20 methylene of 1. This molecule exerted cytotoxic activity against A549 and HT-29 cells with IC50 values of 5.23 and 1.88 microg/mL, respectively. 相似文献
8.
Yohei Nakatsugawa 《Few-Body Systems》2013,54(7-10):1179-1181
The missing mass spectra of ${\gamma p \rightarrow K^{+}X}$ for ${\gamma p \rightarrow K^{+} n \pi^{+}\pi^{-}}$ reaction were measured to obtain the spectrum of Λ(1405). The spectra were measured for two charged decay modes of Λ(1405) separately and they were combined to cancel the effect of interference between the isospin 0 and 1 terms of the Σπ scattering amplitudes. Our goal is to obtain the differential cross section of Λ(1405) and Σ0(1385) photoproduction. The preliminary results are presented here. 相似文献
9.
Photoinduced reaction of o-ethenylaryl isocyanides with organic disulfides in the presence of diphenyl ditellurides affords the corresponding bisthiolated indole derivatives via a radical cyclization process. The cyclization can proceed at room temperature upon visible-light irradiation and exhibits good tolerance to functional groups. Several organic disulfides also can be employed for this cyclization, and the corresponding bisthiolated indole derivatives are obtained selectively. In addition, the photoinduced reaction of o-ethenylaryl isocyanides with bis(2-aminophenyl) disulfide affords tetracyclic compounds in one portion. 相似文献
10.
Toshiro Harada Kousou Kanda Yuuki Hiraoka Yasuhisa Marutani Masashi Nakatsugawa 《Tetrahedron: Asymmetry》2004,15(24):3879-3883
Bis-BINOLs 1a,b in which two BINOL units are tethered by o- and m-phenylenebis(ethynyl) groups form stable dinuclear bis-BINOLate titanium(IV) complexes 2a,b by treatment with titanium tetraisopropoxide. In the presence of excess titanium tetraisopropoxide, 2a and 2b (2–20 mol %) catalyze diethylzinc addition to aromatic and aliphatic aldehydes in an efficient manner to give the ethylation products with high enantioselectivities. While more than 1 equiv of titanium tetraisopropoxide (with respect to a substrate aldehyde) is generally employed for obtaining high turnover frequency and selectivity in reactions catalyzed by a parent (BINOLate)Ti(OiPr)2, the amount can be reduced as low as 0.2 equiv in the reactions catalyzed by 2a,b. 相似文献