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991.
In this paper we characterize the family of external lines to a hyperbolic quadric of PG
(3, q). 相似文献
992.
Osellame R Chiodo N della Valle G Taccheo S Ramponi R Cerullo G Killi A Morgner U Lederer M Kopf D 《Optics letters》2004,29(16):1900-1902
Optical waveguide writing is demonstrated by means of a diode-pumped cavity-dumped Yb:glass femtosecond laser oscillator with a pulse energy of 270 nJ at a 166-kHz repetition rate. Waveguides realized on an Er:Yb-doped phosphate glass are almost perfectly mode matched to standard single-mode fibers at 1.55 microm and show a 1.2-dB net gain in a standard telecommunications amplifier setup. Waveguide writing with a compact femtosecond laser oscillator is an important step toward introducing this technique into an industrial context. 相似文献
993.
Heidorn CJ Rasmussen K Hansen BG Nørager O Allanou R Seynaeve R Scheer S Kappes D Bernasconi R 《Journal of chemical information and computer sciences》2003,43(3):779-786
Because of the large number of chemicals to be risk assessed within the European Union, an electronic data reporting and management tool, IUCLID, was developed supporting all three steps of the risk assessment process, namely data collection, priority-setting, and risk assessment. This paper gives an overview of the IUCLID software, which has been updated and adapted to also be used for the notification phase of the Biocides Program of the European Commission. 相似文献
994.
The bis-barium complex of a butterfly crown ether as a phototunable supramolecular catalyst 总被引:1,自引:0,他引:1
Cacciapaglia R Di Stefano S Mandolini L 《Journal of the American Chemical Society》2003,125(8):2224-2227
Reversible phototuning of the catalytic efficiency of the bis-barium complex of azobis(benzo-18-crown-6) in the basic ethanolysis of anilide derivatives has been achieved by light-induced cis right arrow over left arrow trans interconversion of the azobenzene spacer unit of the catalyst. The geometry of the productive catalyst-substrate complex is more favorable when the concave cis form of the catalyst is involved. Continuous photoregulation of the catalytic activity at any intermediate value between the "HIGH" and "LOW" levels was achieved by proper adjustment of the excitation wavelength or the irradiation time. The complete and relatively fast interconvertibility of photostationary states allowed the activity of the catalyst to be repeatedly photoswitched "HIGH" and "LOW" in the course of the same run. 相似文献
995.
996.
Giuseppe DAscenzo Roberta Curini Aldo Marino Giorgio De Angelis Vincenzo Carunchio 《Thermochimica Acta》1980,39(3):181-185
An analytical method for the quantitative determination of some aminoacids is proposed. The analysis is carried out in two steps. The first is based on a thin layer chromatographic separation (TLC) which is realized on alumina and allows the aminoacids to be separated. The second is based on an application of differential scanning calorimetry (DSC), by which it is possible to characterize and determine the amount of the compound contained in each spot, after having removed from the plate the layer corresponding to the spot. This is put in the sample capsule of the differential scanning calorimeter, while the reference capsule is filled with an identical weight of the sample-free aluminium oxide from the same TLC plate. The DSC signal is proportional to the quantity of the sample present in the spot. 相似文献
997.
998.
999.
1000.
Ingrid Rodrigues Angelita M. Barcellos Andrei L. Belladona Juliano A. Roehrs Roberta Cargnelutti Diego Alves Gelson Perin Ricardo F. Schumacher 《Tetrahedron》2018,74(31):4242-4246
Oxone mediated reaction of imidazo[2,1-b]thiazole, imidazo[1,2-a]pyridine and 1H-pyrazole derivatives with diaryl diselenides is presented here. The methodology represents an efficient and simple protocol for carrying out the selective synthesis of 5-arylselanyl-imidazo[2,1-b]thiazoles, 3-arylselanyl-imidazo[1,2-a]pyridines and 4-arylselanyl-1H-pyrazoles in high yields using a stable, nontoxic and cheap oxidant. The reactions were conducted at 60?°C in air using acetonitrile as solvent. Alternatively, the use of ultrasound irradiation is presented as a tool for fast and efficient energy transfer that significantly reduced the reaction time. 相似文献