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Based on the knowledge characteristics of the chapter on nitrogen group elements, and combined with the teaching experience of our excellent video open course, this paper has probed the teaching reform of inorganic elements chemistry from the following aspects:using the principle of chemistry to explain the structure and properties of substances, designing problems to guide students to think and cultivate their learning ability, instructing students to be good at inducing the changing laws of material properties, paying attention to the relationship between the elements and compounds and practices of production and life. It aims to guide students to learn, memorize and master the knowledge of element chemistry effectively, and improve the quality of classroom teaching. 相似文献
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黄光 《广东微量元素科学》2005,12(3):17-17
郑州市第一人民医院对185例分娩前健康孕妇与足月正常新生儿作发锌、铜测定,其中85人作血清锌、铜测定,10月后随访62例母婴发锌、铜含量.以探讨微量元素锌、铜与优生优育的关系。 相似文献
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铜族金属与完整及氮掺杂石墨烯的相互作用 总被引:1,自引:0,他引:1
基于广义梯度密度泛函理论和周期平板模型,研究了铜族金属单原子和双原子簇与完整及氮掺杂石墨烯的结合情况.结果表明,氮掺杂后石墨烯的电子结构特性由半金属性变为金属性;铜族金属在完整及石墨型氮掺杂石墨烯上的吸附较弱,结合能约为0.5eV,而在吡啶型氮掺杂和吡咯型氮掺杂石墨烯上有较强的化学吸附,结合能一般大于1eV;吡咯型氮掺杂后的构型不稳定,金属原子及簇与包含该结构的石墨烯衬底作用时会使其向吡啶型氮掺杂转变,并最终得到基于吡啶型氮掺杂的稳定吸附构型.Mulliken电荷布居分析显示,吸附在吡啶型氮掺杂石墨烯上的金属单原子与金属双原子簇带电性质相反.态密度及轨道分析表明,Cu与吡啶型氮掺杂石墨烯空位处留有悬挂键的三个原子成键,而Au与其中两个C原子成键. 相似文献
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与科学知识相比,科学方法具有更大的稳定性和更普遍的适用性.特别是进行个人决策时,恰当地运用科学方法是一个人具有良好科学素养的重要标志之一.从这个意义上讲,掌握方法要比掌握知识更为重要. 相似文献
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Angelika S. D. Stahlich Dr. Volker Huch Alexander Grandjean Kevin Rohe Dr. Kinga I. Leszczyńska Prof. Dr. David Scheschkewitz Dr. André Schäfer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(1):173-176
Permethylated disila[2]metallocenophanes of silicon, germanium, tin, lead, 2 a – d , (tetrelocenophanes) and antimony, 3 a , b , (pnictogenocenophanes) are described. In the case of antimony, a chloro-substituted stibonocenophane, 3 a , as well as cationic stibonocenophanium tetrachloroaluminate and tetraphenylborate salts, 3 b [X] (X=[AlCl4], [BPh4]), were synthesized. These represent the first examples of metallocenophanes of any Group 15 element. All compounds were studied in solution and in the solid state. Without exception the ansa-bridge exerts a strong influence on the bending angle of the two Cp-ligands. For disila[2]plumbocenophane, 2 d , its reactivity towards Group 15 halides was probed. Treatment of disila[2]plumbocenophane, 2 d , with two equivalents of phosphorus(III) chloride or arsenic(III) chloride, results in a ring-opening reaction and gives the bis(dihalopnictogenyl)-substituted products, 4 a , b . 相似文献
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Clusters of main group elements are not rare. On the contrary, it is becoming difficult to avoid the discovery of new substances of this type. Clusters are the natural intermediate stages between an element and its isolated atoms or ions. In the form of polycations and polyanions they offer models for the stepwise oxidation and reduction of an element and represent a bridge between the elements. The great majority of homonuclear bonded structures are already present in the solid phases of simple systems. Mobilization of these clusters as molecules represents a great challenge. 相似文献
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《Analytical letters》2012,45(18):3343-3359
Abstract Platinum (Pt), palladium (Pd), rhodium (Rh) and iridium (Ir), the platinum group elements (PGEs), have been reported to induce hypersensitive reactions. The purpose of this research was to assess: (i) the PGEs level in indoor air and in biological samples (blood, urine and hair) of workers involved in the assembly of catalysers and recycling metals; (ii) the prevalence and the clinical characteristics of hypersensitivity to PGEs; (iii) the association between the environmental exposure and the levels of the xenobiotics in biological samples and the presence of PGE allergies. Airborne particles were collected by means of fixed area samplers equipped with a PM10 sampling head and by means of personal devices worn by the workers. Analyses of all the samples were performed by a sector field and a quadrupole inductively coupled plasma mass spectrometry. The highest mean level in PM10 airborne and soluble Pt percentage was found in coating department, while the highest concentrations of total Pd were found in the recycling and in the catalyst chemical departments, also confirmed by the biological data. Positive prick test reactions to PGEs were found in 17 out of the 103 workers who performed skin prick or patch tests. All of the 17 were positive to H2PtCl6, three out 17 also had a positive reaction to IrCl3 and RhCl3 and 1 also had a positive reaction to PdCl2. No differences were observed between subjects with positive or negative skin test to PGEs on mean concentration of the metals in blood, urine and hair. The results show that Pt‐salts are important allergens in the catalyst industry and that the clinical manifestations involve the respiratory system, ocular symptoms and the skin. The concentration of PGEs in biological samples are not correlated with hypersensitivity, but the sensitivity is present only in subjects involved in production processes. 相似文献
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María García‐Castro Dr. Avelino Martín Dr. Miguel Mena Dr. Carlos Yélamos Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(29):7180-7191
Several heterometallic nitrido complexes were prepared by reaction of the imido–nitrido titanium complex [{Ti(η5‐C5Me5)(μ‐NH)}3(μ3‐N)] ( 1 ) with amido derivatives of Group 13–15 elements. Treatment of 1 with bis(trimethylsilyl)amido [M{N(SiMe3)2}3] derivatives of aluminum, gallium, or indium in toluene at 150–190 °C affords the single‐cube amidoaluminum complex [{(Me3Si)2N}Al{(μ3‐N)2(μ3‐NH)Ti3(η5‐C5Me5)3(μ3‐N)}] ( 2 ) or the corner‐shared double‐cube compounds [M(μ3‐N)3(μ3‐NH)3{Ti3(η5‐C5Me5)3(μ3‐N)}2] [M=Ga ( 3 ), In ( 4 )]. Complexes 3 and 4 were also obtained by treatment of 1 with the trialkyl derivatives [M(CH2SiMe3)3] (M=Ga, In) at high temperatures. The analogous reaction of 1 with [{Ga(NMe2)3}2] at 110 °C leads to [{Ga(μ3‐N)2(μ3‐NH)Ti3(η5‐C5Me5)3(μ3‐N)}2] ( 5 ), in which two [GaTi3N4] cube‐type moieties are linked through a gallium–gallium bond. Complex 1 reacts with one equivalent of germanium, tin, or lead bis(trimethylsilyl)amido derivatives [M{N(SiMe3)2}2] in toluene at room temperature to give cube‐type complexes [M{(μ3‐N)2(μ3‐NH)Ti3(η5‐C5Me5)3(μ3‐N)}] [M=Ge ( 6 ), Sn ( 7 ), Pb ( 8 )]. Monitoring the reaction of 1 with [Sn{N(SiMe3)2}2] and [Sn(C5H5)2] by NMR spectroscopy allows the identification of intermediates [RSn{(μ3‐N)(μ3‐NH)2Ti3(η5‐C5Me5)3(μ3‐N)}] [R=N(SiMe3)2 ( 9 ), C5H5 ( 10 )] in the formation of 7 . Addition of one equivalent of the metalloligand 1 to a solution of lead derivative 8 or the treatment of 1 with a half equivalent of [Pb{N(SiMe3)2}2] afford the corner‐shared double‐cube compound [Pb(μ3‐N)2(μ3‐NH)4{Ti3(η5‐C5Me5)3(μ3‐N)}2] ( 11 ). Analogous antimony and bismuth derivatives [M(μ3‐N)3(μ3‐NH)3{Ti3(η5‐C5Me5)3(μ3‐N)}2] [M=Sb ( 12 ), Bi ( 13 )] were obtained through the reaction of 1 with the tris(dimethylamido) reagents [M(NMe2)3]. Treatment of 1 with [AlCl2{N(SiMe3)2}(OEt2)] affords the precipitation of the singular aluminum–titanium square‐pyramidal aggregate [{{(Me3Si)2N}Cl3Al2}(μ3‐N)(μ3‐NH)2{Ti3(η5‐C5Me5)3(μ‐Cl)(μ3‐N)}] ( 14 ). The X‐ray crystal structures of 5 , 11 , 13 , 14 , and [AlCl{N(SiMe3)2}2] were determined. 相似文献
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Formazanate Complexes of Hypervalent Group 14 Elements as Precursors to Electronically Stabilized Radicals 下载免费PDF全文
Ryan R. Maar Sara D. Catingan Prof. Dr. Viktor N. Staroverov Prof. Dr. Joe B. Gilroy 《Angewandte Chemie (International ed. in English)》2018,57(31):9870-9874
The stability of molecular radicals containing main‐group elements usually hinges on the presence of bulky substituents that shield the reactive radical center. We describe a family of Group 14 formazanate complexes whose chemical reduction allows access to radicals that are stabilized instead by geometric and electron‐delocalization effects, specifically by the square‐pyramidal coordination geometry adopted by the Group 14 atom (Si, Ge, Sn) within the framework of the heteroatom‐rich formazanate ligands. The reduction potentials of the Si, Ge, and Sn complexes as determined by cyclic voltammetry become more negative in that order. Examination of the solid‐state structures of these complexes suggested that their electron‐accepting ability decreases with increasing size of the Group 14 atom because a larger central atom increases the nonplanarity of the ligand‐based conjugated π‐electron system of the complex. The experimental findings were supported by density‐functional calculations on the parent complexes and the corresponding radical anions. 相似文献