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31.
Eric G. Bryan Brian F.G. Johnson Jack Lewis 《Journal of organometallic chemistry》1976,122(2):249-252
Treatment of H2Os3(CO)10 with cyclonona-l,2-diene produced HOs3(CO)9C9H13 and Os2(CO)6(C9H4)2. Single crystal X ray analysis has shown that the latter is not isostructural with Fe2(CO)6(C9H14)2. 相似文献
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33.
Mei Y Wu T Xu C Langenbach KJ Elliott JT Vogt BD Beers KL Amis EJ Washburn NR 《Langmuir : the ACS journal of surfaces and colloids》2005,21(26):12309-12314
A simple yet versatile method was developed to prepare a low-density polymerization initiator gradient, which was combined with surface-initiated atom transfer radical polymerization (ATRP) to produce a well-defined poly(2-hydroxyethyl methacrylate) (HEMA) gradient substrate. A smooth variation in film thickness was measured across the gradient, ranging from 20 A to over 80 A, but we observed a nonmonotonic variation in water contact angle. Fits of X-ray reflectivity profiles suggested that at the low graft density end, the polymer chain structure was in a "mushroom" regime, while the polymer chains at high graft density were in a "brush" regime. It was found that the "mushroom" region of the gradient could be made adhesive to cells by adsorbing adhesion proteins, and cell adhesion could be tuned by controlling the density of the polymer grafts. Fibroblasts were seeded on gradients precoated with fibronectin to test cellular responses to this novel substrate, but it was found that cell adhesion did not follow the expected trend; instead, saturated cell adhesion and spreading was found at the low grafting density region. 相似文献
34.
The trans reduction of all types of alkynes to give (E)-olefins is achieved through a two-stage trans hydrosilylation and protodesilylation. Reaction of an alkyne and a silane with the ruthenium catalyst [Cp*Ru(MeCN)3]PF6 results in clean hydrosilylation to give only the (Z)-trans addition product at ambient temperature with catalyst loadings of 1-5 mol %. The crude vinylsilane products are then protodesilylated by the action of cuprous iodide and TBAF at rt-35 degrees C. The reaction is compatible with many sensitive functional groups and provides a general trans-alkyne reduction not possible by other means. 相似文献
35.
Measurements of dipole strengths of chlorophylls in solution are reviewed and correlated. The refractive index dependence is found to be expressible in a simple empirical fashion that does not rely on the concept of vacuum dipole strength. The index dependence in some respects contradicts the dependence expected on the basis of effective field theories. 相似文献
36.
Quantitative comparisons of the product ratios of the mechanistically similar diazomethane and Tiffeneau-Demjanov homologations of 17β-hydroxy-5α-androstan-3-one and 5α-cholestan-3-one have shown that equatorial approach of diazomethane to the C-3 CO group predominates to the extent of 70–79%. The data for both the C-17β-OH and -C8H17 substituted steroids are in close agreement thereby confirming that the C-17 substituents do not exert any significant long range effect on the reactions studied. 相似文献
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38.
Cinabro D Henderson S Liu T Saulnier M Wilson R Yamamoto H Bergfeld T Eisenstein BI Gollin G Ong B Palmer M Selen M Thaler JJ Sadoff AJ Ammar R Ball S Baringer P Bean A Besson D Coppage D Copty N Davis R Hancock N Kelly M Kwak N Lam H Kubota Y Lattery M Nelson JK Patton S Perticone D Poling R Savinov V Schrenk S Wang R Alam MS Kim IJ Nemati B O'Neill JJ Severini H Sun CR Zoeller MM Crawford G Daubenmier CM Fulton R Fujino D Gan KK Honscheid K Kagan H Kass R Lee J Malchow R Morrow F Skovpen Y 《Physical review letters》1994,72(10):1406-1410
39.
Ammar R Ball S Baringer P Bean A Besson D Coppage D Copty N Davis R Hancock N Kelly M Kwak N Lam H Kubota Y Lattery M Nelson JK Patton S Perticone D Poling R Savinov V Schrenk S Wang R Alam MS Kim IJ Nemati B O'Neill JJ Severini H Sun CR Zoeller MM Crawford G Daubenmier CM Fulton R Fujino D Gan KK Honscheid K Kagan H Kass R Lee J Malchow R Morrow F Skovpen Y Sung M White C Butler F Fu X Kalbfleisch G Ross WR Skubic P Snow J Wang PL Wood M Brown DN Fast J McIlwain RL Miao T Miller DH Modesitt M 《Physical review D: Particles and fields》1994,49(11):5701-5704
40.
Thermal and mechanical coupling between successive pulses in KrF-excimer-laser ablation of polyimide
Z. Ball T. Feurer D. L. Callahan R. Sauerbrey 《Applied Physics A: Materials Science & Processing》1996,62(3):203-211
Multiple-shot effects in laser processing and ablation of polyimide are examined and are found to be the dominant phenomena for processes involving several hundreds or thousands of pulses. For fluences less than 260 mJ/cm2, it was found that it is impossible to cut through 75 m polyimide foils for an arbitrarily large number of excimer pulses even though this fluence is more than ten times the single-shot ablation threshold. The halt in etching is due to the formation, over a number of shots, of a robust carbon matrix with a deep surface roughness which is also responsible for laser-induced electrical conductivity. The effect of thermal coupling between successive shots is shown to be a dominant factor in determining the electrical properties of the carbon layer. Differences in electrical conductivity of up to 12 orders of magnitude were found for only small differences in repetition rate. Transmission electron microscopy revealed the changes in microstructure responsible for the dramatic differences in electrical properties. 相似文献