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排序方式: 共有202条查询结果,搜索用时 15 毫秒
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Tohru Takahashi Masatoshi Yoshimura Hiroyasu Suzuka Tomohiro Maegawa Yoshinari Sawama Yasunari Monguchi Hironao Sajiki 《Tetrahedron》2012,68(39):8293-8299
Palladium catalysts embedded on molecular sieves (MS3A and MS5A) were prepared by the adsorption of Pd(OAc)2 onto molecular sieves with its in situ reduction to Pd0 by MeOH as a reducing agent and solvent. 0.5% Pd/MS3A and 0.5% Pd/MS5A catalyzed the hydrogenation of alkynes, alkenes, and azides with a variety of coexisting reducible functionalities, such as nitro group, intact. It is noteworthy that terminal alkenes of styrene derivatives possessing electron-donating functionalities on the benzene nucleus were never hydrogenated under 0.5% Pd/MS5A-catalyzed conditions, while internal alkenes of 1-propenylbenzene derivatives were readily reduced to the corresponding alkanes. 相似文献
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An in-water dehydrative alkylation with a novel heterobimetallic polymeric catalyst is described. Thus, a boron-iridium heterobimetallic polymeric catalyst was prepared by ionic convolution of a poly(catechol borate) and an iridium complex. The alkylation of ammonia and amines with alcohols, alkylating agents, was performed with 1 mol % Ir of the heterogeneous catalyst in water without the use of organic solvents under aerobic conditions to give the corresponding alkylated amines. 相似文献
77.
The reaction of tetrabutoxyoctadehydrodibenzo[12]annulene 2f with iodine under aerobic conditions was reexamined. Contrary to previous reports, the present results revealed the formation of both anti-diiodoindenofluorenedione and its syn isomer through the oxidation of the respective tetraiodoindenofluorenes, indicating the occurrence of two modes of iodine-induced transannular cyclization. This was supported by the reaction of 2f with bromine, which gave anti- and syn-hexabromodihydroindenofluorenes through interception of indenofluorene intermediates by bromine. The hexabromides were transformed into the corresponding dibromodiones by hydrolysis. 相似文献
78.
Yoshinari Abe Izumi Nakai Kazumitsu Takahashi Nozomu Kawai Sakuji Yoshimura 《Analytical and bioanalytical chemistry》2009,395(7):1987-1996
Blue-painted pottery was produced in the New Kingdom, Egypt, and decorated with blue, red, and black pigment. In this study,
two newly developed portable instruments, a portable X-ray fluorescence spectrometer and a portable X-ray powder diffractometer,
were brought to the site on the outcrop at Northwest Saqqara, an archaeological site in Egypt, to verify their performance
in on-site analysis of excavated artifacts at the site. Pigments used for the blue-painted pottery and plasters in the New
Kingdom were analyzed by these instruments on the basis of both their chemical compositions and crystal-structural information.
The blue pigments were identified as two different pigments, Egyptian blue and cobalt blue. The diffraction pattern of the
blue pigment of the painted pottery exhibited that of spinel structure. The XRF spectrum of the blue pigment obtained by the
same instrument from the same position indicates the presence of Mn, Co, Fe, Ni, and Zn. The possibility of compositional
transitions of the cobalt blue pigment with time was revealed on by detailed analysis of the XRF data. The reason for the
transitions is considered together with the archaeological background of the New Kingdom, Egypt. 相似文献
79.
Investigation of cadmium accumulation mechanism in hepatopancreas of Patinopecten yessoensis by synchrotron radiation X‐ray absorption fine structure and synchrotron radiation X‐ray fluorescence analyses 下载免费PDF全文
Kenji Terada Yoshinari Abe Izumi Nakai Shingo Maruhashi Shigetoshi Miura Kotaro Honda Yasuhiro Tomooka 《X射线光谱测定》2018,47(2):137-143
Chemical state of cadmium in a hepatopancreas of a scallop (Patinopecten yessoensis) was studied by means of synchrotron radiation‐based X‐ray analytical techniques. X‐ray absorption fine structure (XAFS) and X‐ray fluorescence (XRF) imaging were used to identify the chemical state and the distribution of cadmium in the hepatopancreas, respectively. The results of in vivo Cd K‐edge XAFS suggested that the neighboring atoms of the cadmium in the hepatopancreas are of sulfur. Therefore, we propose that cadmium was accumulated by a metalloprotein with sulfur. Micro XRF imaging of thin sections of the hepatopancreas showed that cadmium is distributed on the surface of intestinal epithelia and concentrated in the internal tissue of the hepatopancreas. These results indicated that scallops accumulate cadmium inside the hepatopancreas through the intestinal epithelium. 相似文献
80.
Fukuchi M Inukai M Takeda K Takegoshi K 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2008,194(2):300-302
We propose a new data-acquisition scheme for 2D separation experiments to save the spectrometer time by 1/2. This scheme, referred to as a double-acquisition scheme, is applicable to most of separation experiments with the hypercomplex time-domain data-acquisition scheme (the States method) for data collection. 相似文献