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991.
营养学家们已经确定了锰、钻、镍、铜、锌、砷、钼和锶等10多种人体所必需的痕量元素,它们对于维持人体的健康和长寿起着重要的生理作用。本文首次应用等离子炬-质谱技术测定了白菜、萝卜、大豆和土壤中这八种痕量元素的含量,并报告了它们的测定结果和标准偏差,其中土壤样品的测定值与参考值相比较,经 T 检验,两者之间在统计学上,没有显著性差异。实验证明该方法可对多种痕量元素同时定性、定量分析。操作简便、快速,灵敏度高;方法准确可靠,重现性好。为开展食品卫生学、营养学的研究,提供了更为先进的测试技术。 相似文献
992.
993.
994.
CO和H2与Ni基催化剂的相互作用研究 总被引:3,自引:0,他引:3
用活性测试和程序升温动态红外光谱方法研究了CO和H2在Ni/Al2O3催化剂上的行为,并用量子化学从头算方法进行了模拟表征。结果表明,在较低温度下,CO在Ni/Al2O3上的线式吸附态和桥式吸附态相比,桥式对CO压力更敏感,而线式则对温度更敏感。 相似文献
995.
同时萃取-火焰原子吸收光度法测定锂盐及某些盐中锰、铬、铜、锌、镉、铁、钴、镍和铅 总被引:1,自引:0,他引:1
本文系用二乙基二硫代氨基甲酸二乙铵(DEDTC)/甲基异丁基甲酮(MIBK)pH5.7萃取体系,预浓缩以后,用原子吸收法在RbCl、 CsCl、 Sr(NO_3)_2、H_3BO_3、NH_4NO_3、NaBr、KI、Li_2CO_3、NaCl、KCl、CaCl_2、MgO、BaCl_2、KH_2pO_4、KNaC_4H_4O_6、C_6H_6O_7等盐类中测定痕量的锰、铬、铜、锌、镉、铁、钴、镍、铅等九个元素,其中应用于前面七个样品是我们提出的。检出限为1×10~(-4)%,九个元素的回收率在93~106%之间,相对标准偏差(n=7)为2.7%。 相似文献
996.
Constantinos G. Efthymiou Constantina Papatriantafyllopoulou Nadia I. Alexopoulou Catherine P. Raptopoulou Roman Boča Jerzy Mrozinski Evangelos G. Bakalbassis Spyros P. Perlepes 《Polyhedron》2009
The reactions of 2-(hydromethyl)pyridine, hmpH, with Ni(O2CMe)2·4H2O in H2O, in the absence of counterions, have been investigated. The synthetic study has led to the two new complexes [Ni(O2CMe)2(hmpH)2] (1) and [Ni4(O2CMe)4(hmp)4(H2O)2] (2). Complex 1 can also be transformed into 2 by reacting with an excess of NaOH in H2O. The structures of 1 and 2·2.25H2O·0.5(1,4-dioxane) have been solved by single-crystal, X-ray crystallography. The octahedral NiII center in centrosymmetric 1 is coordinated by two 1.10 (Harris notation) MeCO2− groups and two N,O-chelating (1.11) hpmH ligands. The tetranuclear cluster molecule of 2·2.25H2O·0.5(1,4-dioxane) possesses a distorted cubane {Ni4(μ3-OR′)4}4+ core [R′ = (2-pyridyl)CH2–] with the NiII ions and the oxygen atoms from the 3.31 hmp− ligands occupying alternate vertices of the cube. Two 2.11 MeCO2− groups cap two opposite faces of the cube, while two 1.10 MeCO2− ions and two aqua ligands complete the octahedral coordination sphere of the metal centers. Characteristic IR bands for the two complexes are discussed in terms of the nature of bonding and the structures of the two complexes. The variable-temperature magnetic properties of 2 have been modeled with two J values, and reveal antiferromagnetic exchange interactions between the four NiII ions to give a diamagnetic ground state. 相似文献
997.
Matthew J. Fuchter Sven M. Baum Efstathia G. Sakellariou Todd Miller Andrew J.P. White Anthony G.M. Barrett Brian M. Hoffman 《Tetrahedron》2005,61(25):6115-6130
The syntheses of a variety of substituted diaminomaleonitriles, with variable nitrogen substituents, were undertaken. Linstead macrocyclization of the resulting diaminomaleonitriles gave access to a wide range of functionalized porphyrazine-octaamines and hexamines and norphthalocyaninediamines. Conversion of these macrocycles into metallic derivatives and studies of their electronic absorption, solubility and electrochemistry are described. These flexible tetraazaporphyrins show potential in a range of applications including biomedical agents, novel charge-transfer complexes, chemical sensors, novel electronic materials and non-linear optics. 相似文献
998.
Dong-heng Zhang Su-yun Jie Hai-jian Yang Fei Chang Wen-hua Sun Key Laboratory of Engineering Plastics Institute of Chemistry Chinese Academy of Sciences Beijing China 《高分子科学》2005,23(6)
A series of salicylaldimines,synthesized in high yield via microwave-assisted condensation of salicylaldehyde and 2-alkoxyaniline were allowed to react with nickel chloride to form six-coordinated nickel complexes.These nickel complexes were carefully characterized,and the solid structure of la was elucidated by X-Ray diffraction.Activated with MAO,the nickel complexes showed good activity for homopolymerization of norbornene.Reaction parameters,such as the ratio of nickel precursor to MAO,monomer concentration,reaction time and the reaction temperature,as well as the nature of the ligands were found to have significant effects on the catalytic activity and some properties of the resulting polynorbornene. 相似文献
999.
Phosphoraneiminato Complexes of Manganese(II) and Nickel(II) with Heterocubane Structure. Crystal Structures of [MCl(NPEt3)]4 with M = Mn and Ni The phosphoraneiminato complexes [MCl(NPEt3)]4 with M = manganese and nickel as well as [MnBr(NPEt3)]4 are formed from the anhydrous halides MX2 and excess phosphoraneimine Me3SiNPEt3 by fusion reaction. They form paramagnetic, moisture-sensitive, orange (M = Mn) and turquoisegreen (M = Ni) crystals, respectively, which are characterized by i.r. spectroscopy and by crystal structure determinations. [MnCl(NPEt3)]4 ( 1 ): Space group C2/c, Z = 4, structure solution with 3 591 unique reflections, (2 811 > 2σ(I)) R = 0.036. Lattice dimensions at -50°C: a = 2104.3, b = 1100.6, c = 1966.5 pm, β = 115.87°. [NiCl(NPEt3)]4 ( 2 ): Space group C2/c, Z = 4, structure solution with 2 711 unique reflections, (1611 > 2σ(I)) R = 0.056. Lattice dimensions at ?50°C: a = 2051.6, b = 1099.2, c = 1954.6 pm, β = 115.80°. 1 and 2 are isostructural with one another. They form heterocubane structures in which the metal atoms are linked via μ3-N-bridges of the phosphoraneiminato groups with M4N4 bridge-type bond angles close to 90°. 相似文献
1000.
G.?Perentzis E.?Horopanitis I.?Samaras S.?Kokkou L.?PapadimitriouEmail author 《Journal of Solid State Electrochemistry》2003,8(1):51-54
Cathode powders of the Li–Mn–Ni–O system have been prepared at a Mn/(Mn+Ni) ratio varying from 0 to 1. The solid state reaction method was used to obtain the cathode materials by mixing MnO2, LiCO3 and NiO. A 20% excess of lithium was used in the precursors. The materials produced were examined by X-rays to identify their structure. Batteries were assembled by using these materials as cathode with a liquid electrolyte consisting of EC/DC 1:1, 1 LiPF6 and Li anode. Their capacity, cycle fading and charge-discharge conditions were evaluated.Presented at the 3rd International Meeting "Advanced Batteries and Accumulators", June 16th–June 20th 2002, Brno, Czech Republic 相似文献