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991.
T. Chen C. Li X. Y. Liu L. H. Wang Z. Zheng X. Y. Wang C. L. Liu 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(1):219-225
The fate and migration behavior of radionuclides in environment are influenced by a series of physical and chemical processes such as advection, hydrodynamic dispersion (including mechanical dispersion and molecular diffusion), retention, chemical reaction and so on. In this study, the migration of 125I? in Beishan granite and the potential retention of iodine by silver halide additives were investigated by a pulse injection column method. All breakthrough curves were analyzed according to the analytical solution of transport equation and the dispersion coefficient (D), and first-order sorption constant (k) were obtained. For conservative nuclide, the dispersion behavior is only related to the dispersion medium. Silver halides were proved having sorption ability for 125I? in the order of AgCl > AgBr > AgI. The transport of iodine in the crushed granite column can be adequately described by the advection–dispersion equation with a first-order, irreversible sorption term. The pulse injection column method can be used as a fast method to evaluate the sorption or retention ability of solid phase. 相似文献
992.
993.
Under solid-liquid PTC conditions, treatment of 1-nitro-4-(4-nitrophenylsulfonyl-methyl)benzene(1) with α,β -unsaturated esters (2a-h) at 35–75°C gave tandem addition-rearrangement products(3a-h). While at higher temperature(75°C), addition-rearrangement-addition products (4a-b) were obtained when acrylates were used. Finally a possible mechanism is proposed. 相似文献
994.
The Vilsmeier reaction of nickel(II) chlorin P6 trimethyl ester with 3-dimethyl-aminoacrolein yielded nickel(II) chlorin P6 20-(2-formylvinyl) trimethyl ester and nickel(II) chlorin P6 3-(1-hydroxyethyl)-3-devinyl-20-(2-formylvinyl) trimethyl ester. Also, the outgrowths of nickel(II) chlorin P6 20-(2-formyl) trimethyl ester and nickel(II) chlorin P6 3-(2-formylvinyl)-3-devinyl-20-(2-formyl) trimethyl ester were obtained by Vilsmeier reaction with dimethylformamide. By treating the derivatives of nickel(II) 20-(2-formyl)-chlorin and nickel(II) 3-(2-formylvinyl)-20-(2-formyl)-chlorin with trifluoracetic acid, the removal of the central nickel(II) ion was accomplished. The derivatives of 20-(2-formyl)-chlorin and 3-(2-formylvinyl)-20-(2-formyl)-chlorin demonstrated considerable bathochromic shift of the major absorption band in the red region of the optical spectrum. 相似文献
995.
Abstract Cefpirome was synthesized in 37.7% overall yield from 3-chloromethyl-7-phenylacetylamino cephalosporanic acid p-methoxybenzyl ester (GCLE) by sequential substitution of C-3 chloride with iodide and 2,3-cyclopentenopyridine, followed by a one-pot procedure including deprotection of carboxyl group, hydrolysis of 7-phenylacetamido, and reaction with 2-mercaptobenzothiazolyl-(Z)-2-(2-aminothiazol-4-yl)-2-methoxyiminoacetate (MAEM). The reaction conditions were as follows: obtained from GCLE at low temperature (?5 to 0 °C) and absence of light, 3-iodomethyl-7-phenylacetylamino cephalosporanic acid p-methoxybenzyl ester (GILE) without purification was reacted directly with 2,3-cyclopentenopyridine, in which the molar ratio of GCLE, NaI, and 2,3-cyclopentenopyridine was 1:2:4, and the molar ratio of the resulting compound p-methoxybenzyl 7-phenylacetylamido-3-(2,3-cyclopenteno-1-pyridinio)methyl-3-cephem-4-carboxylate iodide and MAEM was 1:1.1. The structure of the intermediate and the target compound obtained were determined by nuclear magnetic resonance spectra and mass spectroscopy. 相似文献
996.
PdCl2(PCy3)2-catalyzed cyclocarbonylative coupling of ortho-chloro arylketimines with CO has been investigated to develop an efficient method for the synthesis of isoindolin-1-ones. The developed synthetic method has the advantages of having easily available starting materials, high atom-economy, and high selectivity. 相似文献
997.
Biao Yang Guang-Ying Chen Xiao-Ping Song Liu-Qing Yang Chang-Ri Han Xiang-Yang Wu Cai-Juan Zheng Xu Ran Ri-Feng Tang 《Tetrahedron letters》2013
Phytochemical study of the twigs of Trigonostemon xyphophylloides led to the isolation of six new heterodimers, trigoxyphins O (1) and R–T (4–6) comprising of two different degraded diterpenoids, and trigoxyphins P (2) and Q (3) comprising a degraded diterpenoid and a phenylpropanoid, together with a known homodimer, neoboutomannin (7). The structures and relative configurations were elucidated on the basis of extensive spectroscopic analysis, including 1D and 2D NMR experiments. Compounds 1–6 were evaluated for their cytotoxicity against four human tumour cell lines by MTT assay. 相似文献
998.
Xiao‐Ying Cheng Ming‐Fang Wang Zheng‐Yin Yang Yong Li Zeng‐Chen Liu Qiao‐Xia Zhou 《无机化学与普通化学杂志》2013,639(5):832-841
The Schiff base ligand, 1‐phenyl‐3‐methyl‐5‐hydroxypyrazole‐4‐methylene‐8′‐quinolineimine, and its CuII, ZnII, and NiII complexes were synthesized and characterized. The crystal structure of the ZnII complex was determined by single‐crystal X‐ray diffraction, indicating that the metal ions and Schiff base ligand can form mononuclear six‐coordination complexes with 1:1 metal‐to‐ligand stoichiometry at the metal ions as centers. The binding mechanism and affinity of the ligand and its metal complexes to calf thymus DNA (CT DNA) were investigated by UV/Vis spectroscopy, fluorescence titration spectroscopy, EB displacement experiments, and viscosity measurements, indicating that the free ligand and its metal complexes can bind to DNA via an intercalation mode with the binding constants at the order of magnitude of 105–106 M –1, and the metal complexes can bind to DNA more strongly than the free ligand alone. In addition, antioxidant activities of the ligand and its metal complexes were investigated through scavenging effects for hydroxyl radical in vitro, indicating that the compounds show stronger antioxidant activities than some standard antioxidants, such as mannitol. The ligand and its metal complexes were subjected to cytotoxic tests, and experimental results indicated that the metal complexes show significant cytotoxic activity against lung cancer A 549 cells. 相似文献
999.
The applications of a new supported tribromide reagent based on poly(vinylbenzyltrimethylammonium hydroxide) resin (Amberlite 717) were reported. This supported tribromide resin was used directly in α-bromination and α-bromoacetalization of acetophenones without any other catalyst under mild conditions. The effects of solvents and the amount of the supported tribromide resin on the reactions were investigated. Under the optimal conditions, most of α-bromo and α-bromoacetal of acetophenones were selectively obtained in excellent yields. 相似文献
1000.
The condensation of indene or 2-nitrofluorene with aromatic aldehydes catalyzed by bis-(p-methoxyphenyl)telluroxide (BMPTO) under ultrasonic wave irradiation gave corresponding fulvenes in fair to good yield. 相似文献