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排序方式: 共有207条查询结果,搜索用时 46 毫秒
101.
H. Backe Th. Blönnigen M. Dahlinger U. Doppler P. Graffé D. Habs M. Hies Ch. Illgner H. Kunz W. Lauth H. Schöpe P. Schwamb W. Theobald R. Zahn 《Hyperfine Interactions》1992,74(1-4):47-57
The feasibility of a hyperfine spectroscopy on242mAm fission isomers has been demonstrated at the low target production rate of 10/s. The experimental method employed is based
on resonance ionization spectroscopy in a buffer gas cell with detection of the ionization process by means of the fission
decay of the isomers. The resonance ionization has been performed in two steps, utilizing an excimer dye laser combination
with a repetition rate of 300 Hz. The first resonant step proceeds through theJ=7/2 term at 21440.35 cm−1, which has been excited with the tuncable dye laser beam of a wavelength of 466.28 nm, the second non-resonant step is achieved
with the 351 nm radiation of the excimer laser itself, running with XeF. The frequency scan of the tuneable dye laser exhibits
a broad resonance ionization signal, the width of which is most likely explained by the magnetic hyperfine interaction. 相似文献
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Jacques Laleve Mohamad‐Ali Tehfe Frdric Dumur Didier Gigmes Bernadette Graff Fabrice Morlet‐Savary Jean‐Pierre Fouassier 《Macromolecular rapid communications》2013,34(3):239-245
Two new photoinitiators with unprecedented light absorption properties are proposed on the basis of a suitable truxene skeleton where several UV photoinitiators PI units such as benzophenone and thioxanthone are introduced at the periphery and whose molecular orbitals MO can be coupled with those of the PI units: a red‐shifted absorption and a strong increase of the molecular extinction coefficients (by a ≈ 20–1000 fold factor) are found. These compounds are highly efficient light‐harvesting photoinitiators. The scope and practicality of these photoinitiators of polymerization can be dramatically expanded, that is, both radical and cationic polymerization processes are accessible upon very soft irradiation conditions (halogen lamp, LED…︁) thanks to the unique light absorption properties of the new proposed structures. 相似文献
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Novel panchromatic photopolymerizable matrices: N,N'‐dibutylquinacridone as an efficient and versatile photoinitiator 下载免费PDF全文
Jing Zhang Frédéric Dumur Mariem Bouzrati Pu Xiao Céline Dietlin Fabrice Morlet‐Savary Bernadette Graff Didier Gigmes Jean Pierre Fouassier Jacques Lalevée 《Journal of polymer science. Part A, Polymer chemistry》2015,53(14):1719-1727
N,N'‐dibutylquinacridone (DBQA) is utilized here for the first time as a high‐performance panchromatic photoinitiator for the cationic polymerization (CP) of epoxides, the free radical polymerization (FRP) of acrylates, the thiol‐ene polymerization and the synthesis of interpenetrated polymer networks (epoxide/acrylate) under violet, blue, green and yellow lights (emitted from LED at 405 nm, 470 nm, 520 nm, or 594 nm, or laser diode at 532 nm). It confers a panchromatic character to the photopolymerizable matrices. Remarkably, the proposed DBQA based photoinitiating systems exhibit quite excellent efficiency (the final monomer conversion for multifunctional monomers at room temperature can reach 62% and 50% in CP and FRP, respectively) and appear as much more powerful than the camphorquinone or Eosin‐Y containing reference systems for visible light. For green light, DBQA is much more reactive than the literature reference (Eosin‐Y) and for blue light, a good reactivity is found compared with camphorquinone. The photochemical mechanisms are studied by molecular orbital calculations, steady state photolysis, fluorescence, cyclic voltammetry, laser flash photolysis, and electron spin resonance spin trapping techniques. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1719–1727 相似文献
107.
Aurélien Coelho Mahasoa-Salina Souvenir Zafindrajaona Alexis Vallée Prof. Dr. Jean-Bernard Behr Dr. Jean-Luc Vasse 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(3):e202103789
The diastereoselective access to cyclopentanols and N,O-dimethylcyclopentylhydroxylamines from 4-pentenoic acid-derived Weinreb amides is described. Based on the concomitant generation of both the nucleophilic and the electrophilic poles by hydrozirconation of the amide and the C=C double bond, the cyclisation may be tuned towards cyclopentanols or N,O-dimethylcyclopentylhydroxylamines depending on the ring-closure promotor. An extension to cis 3-substituted N,O-dimethylcyclohexylhydroxylamines is also presented. 相似文献
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K.F. Graff 《Ultrasonics》1975,13(3):103-109
Ultrasonics has been used in cutting processes for many years. Slurry drilling is one area, for example, that has attained an accepted, though limited, status in manufacturing technology. Ultrasonic twist drilling is a more recent process aimed at achieving faster cutting speeds. Numerous other metal cutting configurations have been studied with varying success. Certain non-manufacturing applications, such as rock cutting and surgical and dental cutting tasks have emerged. This paper reviews these various areas, including the degree of commercial usage. 相似文献
110.