排序方式: 共有21条查询结果,搜索用时 562 毫秒
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Anthony W. Coleman C. Mitchell Means Simon G. Bott Jerry L. Atwood 《Journal of chemical crystallography》1990,20(2):199-201
[NBu4][Br3] interacts with C6H6 to form an air-stable liquid clathrate. The tribromide anion reacts with phenol to give para-bromophenol in>95% yield. The HBr which is generated in the reaction combines with the Br– anion to form [Br-H-Br]–. The latter forms the basis for a new liquid clathrate, [NBu4][Br-H-Br]·n C6H6. The parent salt, [NBu4][Br3], crystallizes in the monoclinic space group C2/c witha=12.983(5),b=10.380(7),c=16.222(6) Å,=93.93(3)°, andD
c
=1.47 g cm–3 forZ=4. The final R value is 0.068 based on 787 observed reflections. 相似文献
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Hongming Zhang C. Mitchell Means N. Carlene Means Jerry L. Atwood 《Journal of chemical crystallography》1985,15(5):445-452
The title compound was prepared by the addition of A1Me3 to a suspension of 18-crown-6 inp-xylene. The large, colorless, air-sensitive crystals belong to the monoclinic space group P21/n witha=14.822(6),b=7.894(4),c=18.805(6) Å,=105.40(4)°, andD
calc=1.03 g cm–3 forZ=2. The finalR value based on 1758 observed reflections is 0.043. The molecule lies on a crystallographic inversion center and exhibits four strong Al-O bonds. The two independent Al-O distances are 1.978(3) and 2.000(3) Å. The oxygen atoms deviate from the mean plane of the crown, alternating above and below, by 0.13, 0.15, and 0.20 Å, respectively. Thep-xylene molecule is also positioned about a center of inversion. 相似文献
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Experimental evidence of trapped electrons in ions acoustic nonlinear waves and solitons propagating in a stable plasma is reported. Agreement between theory and experiment was found for the dependency of the energy of the trapped electrons versus wave amplitude. 相似文献
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Means JC Olsen PD Schoffers E 《Journal of the American Society for Mass Spectrometry》2003,14(9):1057-1066
Polycyclic aromatic amines (arylamines) are a class of chemical carcinogens that are prevalent in environmental and industrial settings. They are metabolically activated to covalently bond to DNA, forming mutagenic adducts. In order to study the mechanisms of their toxicity, sensitive and selective quantitative LC/MS/MS detection methods were developed to measure the N-(adenin-8-yl)-benzidine adduct and N-(adenin-8-yl)-2-aminofluorene in total DNA extract samples. A novel synthetic method using a palladium catalyst was previously developed to prepare authentic and deuterated arylamine-adenine adducts to serve as standards. These standards were then used to develop an HPLC electrospray ionization tandem mass spectrometry, isotope dilution method. Sample detection limits in DNA samples were 22 pg on-column and 51 pg on-column for the N-(adenin-8-yl)-benzidine- and N-(adenin-8-yl)-2-aminofluorene-adenine adducts, respectively. This method has applications for the study of DNA adduct formation as a biological marker of exposure to carcinogens and for environmental and workplace monitoring of these aromatic amines. 相似文献
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Schaak RE Sra AK Leonard BM Cable RE Bauer JC Han YF Means J Teizer W Vasquez Y Funck ES 《Journal of the American Chemical Society》2005,127(10):3506-3515
Intermetallic compounds and alloys are traditionally synthesized by heating mixtures of metal powders to high temperatures for long periods of time. A low-temperature solution-based alternative has been developed, and this strategy exploits the enhanced reactivity of nanoparticles and the nanometer diffusion distances afforded by binary nanocomposite precursors. Prereduced metal nanoparticles are combined in known ratios, and they form nanomodulated composites that rapidly transform into intermetallics and alloys upon heating at low temperatures. The approach is general in terms of accessible compositions, structures, and morphologies. Multiple compounds in the same binary system can be readily accessed; e.g., AuCu, AuCu3, Au3Cu, and the AuCu-II superlattice are all accessible in the Au-Cu system. This concept can be extended to other binary systems, including the intermetallics FePt3, CoPt, CuPt, and Cu3Pt and the alloys Ag-Pt, Au-Pd, and Ni-Pt. The ternary intermetallic Ag2Pd3S can also be rapidly synthesized at low temperatures from a nanocomposite precursor comprised of Ag2S and Pd nanoparticles. Using this low-temperature solution-based approach, a variety of morphologically diverse nanomaterials are accessible: surface-confined thin films (planar and nonplanar supports), free-standing monoliths, nanomesh materials, inverse opals, and dense gram-scale nanocrystalline powders of intermetallic AuCu. Importantly, the multimetallic materials synthesized using this approach are functional, yielding a room-temperature Fe-Pt ferromagnet, a superconducting sample of Ag2Pd3S (Tc = 1.10 K), and a AuPd4 alloy that selectively catalyzes the formation of H2O2 from H2 and O2. Such flexibility in the synthesis and processing of functional intermetallic and alloy materials is unprecedented. 相似文献