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排序方式: 共有221条查询结果,搜索用时 406 毫秒
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Alexopoulos T Allen C Anderson EW Areti H Banerjee S Beery PD Biswas NN Bujak A Carmony DD Carter T Cole P Choi Y De Bonte RJ Erwin AR Findeisen C Goshaw AT Gutay LJ Hirsch AS Hojvat C Kenney VP Lindsey CS LoSecco JM McMahon T McManus AP Morgan N Nelson KS Oh SH Piekarz J Porile NT Reeves D Scharenberg RP Stampke SR Stringfellow BC Thompson MA Turkot F Walker WD Wang CH Wesson DK 《Physical review letters》1990,64(9):991-994
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Kate J. Graham Chris P. Schaller Brian J. Johnson John B. Klassen 《The Chemical Educator》2002,7(6):376-378
The incorporation of research projects into undergraduate chemistry courses provides a perspective that is fundamentally unavailable in most laboratory experiences. While independent, multistep synthesis projects in organic chemistry have been reported previously, most efforts have been directed at relatively restricted, closely guided research plans with modest student participation in the experimental design. We have implemented a more open-ended synthesis project, limited principally by cost, safety and availability of materials. In the second semester of the sophomore organic sequence, students develop multiple drafts of a plan for a three-to-four-step synthesis. Subsequently, students obtain their own literature protocols for the individual steps. The synthesis is performed over three four-hour laboratory periods. The students conclude this project with a poster presentation of the results at the end of the semester. Evaluation of the students work focuses not only on the successful synthesis of the target but also on planning, troubleshooting, purification, and spectral analysis. 相似文献
4.
Lazarus EA Navratil GA Greenfield CM Strait EJ Austin ME Burrell KH Casper TA Baker DR DeBoo JC Doyle EJ Durst R Ferron JR Forest CB Gohil P Groebner RJ Heidbrink WW Hong R Houlberg WA Howald AW Hsieh C Hyatt AW Jackson GL Kim J Lao LL Lasnier CJ Leonard AW Lohr J La Haye RJ Maingi R Miller RL Murakami M Osborne TH Perkins LJ Petty CC Rettig CL Rhodes TL Rice BW Sabbagh SA Schissel DP Scoville JT Snider RT Staebler GM Stallard BW Stambaugh RD St John HE Stockdale RE Taylor PL Thomas DM 《Physical review letters》1996,77(13):2714-2717
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Lee LF Adronov A Schaller RD Fréchet JM Saykally RJ 《Journal of the American Chemical Society》2003,125(2):536-540
Near-field scanning optical microscopy (NSOM) has been used to investigate the photophysical characteristics of first- to fourth-generation (G1 to G4) light-harvesting dendrimer thin films containing coumarin-343 and coumarin-2 as the core and peripheral chromophores, respectively. Thin film photoluminescence (PL) spectra exhibit a significant red shift in the lower generations (G1, G2, and G3) as compared to their respective solution PL spectra, implying the formation of excimers. Spatially resolved PL NSOM images exhibit pronounced nanoscopic domains in G1, which become more homogeneous in higher generations due to site-isolation of the core chromophore. G4 exhibits complete site-isolation for these light-harvesting dendrimer films. 相似文献
8.
F. Schaller W. Schwarz H.-D. Hausen K. W. Klinkhammer J. Weidlein 《无机化学与普通化学杂志》1997,623(9):1455-1466
Base-free Tris(trimethylsilyl)methyl Derivatives of Lithium, Aluminium, Gallium, and Indium Base-free LiR* (R*=-C(SiMe3)3) has been prepared from R*Cl and Li-metal in toluene at 85?90°C and used to synthesize the metallanes R*MMe2 with M = Al, Ga and In, respectively. The NMR (1H, 13C, 29Si) and the vibrational spectra of these trisyl compounds have been discussed. AlCl3 and LiR*(ratio 1 : 1) forms the metallate metallate Li[R*AlCl3]. The triclinic unit cell (space group P1 ) consists of a centrosymmetric assoziate, formed by four Li[R*AlCl3]- units with Al? Cl…?Li bridges, two pairs of Li-atoms differing in their chlorine-coordination and two disordered toluene molecules, inserted in the crystal lattice (R1wR2 =0,0444/0,1072). The reaction of GaCl3 with LiR* (I :1) gives the unusual sesquichloride (R*Ga(Cl1,33)Me0,67)3 in moderate yield. The X-ray structure determination shows a Ga3Cl3-skeleton with chairconformation and disordered, terminal gallium ligands (R1/wR2= 0,0646/0,2270). 相似文献
9.
H. Budzikiewicz U. Schaller H. Korth G. Pulverer 《Monatshefte für Chemie / Chemical Monthly》1979,110(4):947-953
Alkyl and alkenyl quinolines (so-called Pyo-substances) and theirN-oxides were isolated fromPseudomonas aeruginosa. Structures proposed earlier could be confirmed; a new representative (Pyo V) is described.
IV. Mitt.:A. Römer, H. Budzikiewicz, H. Korth undG. Pulverer, Tetrahedron Letters1979, 509. 相似文献
10.
Dr. Patricia Latza Dr. Patrick Gilles Dr. Torsten Schaller Prof. Dr. Thomas Schrader 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(36):11479-11487
Rational design in combination with a screening process was used to develop affinity polymers for a specific binding site on the surface of immunoglobulin G (IgG) proteins. The concept starts with the identification of critical amino acid residues on the protein interface and their topological arrangement. Appropriate binding monomers were subsequently synthesized. Together with a sugar monomer (2–5 equiv) for water solubility and a dansyl monomer (0.5 equiv) as a fluorescent label, they were subjected in aqueous solution to linear radical copolymerization in various compositions (e.g., azobisisobutyronitrile (AIBN), homogeneous water/DMF mixtures). After ultrafiltration and lyophilization, colorless dry water‐soluble powders were obtained. NMR spectroscopic and gel permeation chromatography (GPC) characterization indicated molecular weights between 30 and 500 kD and confirmed retention of monomer composition as well as the absence of monomers. In a competitive enzyme‐linked immunosorbent assay (ELISA) screen of the polymer libraries (20–50 members), few copolymers qualified as strong and selective binders for the protein A binding site on the Fc fragment of the antibody. Their monomer composition precisely reflected the critical amino acids found at the interface. The simple combination of a charged and a nonpolar binding monomer sufficed for selective submicromolar IgG recognition by the synthetic polymer. Affinities were confirmed by fluorescence titrations; they increased with decreasing salt load but remained largely unaltered at lowered pH. Other proteins, including those of similar size and isoelectric point (pI), were bound 10–1000 times less tightly. This example indicates that interaction domains in other proteins may also be targeted by synthetic polymers if their comonomer composition reflects the nature and arrangement of amino acid residues on the protein surface. 相似文献