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JM Pakarinen H Moisio S Holopainen P Vainiotalo 《Rapid communications in mass spectrometry : RCM》1999,13(14):1485-1490
2-Methoxyethanol chemical ionization of amines, carboxylic acids and amino acids has been found to produce numerous adduct ions. The most intense adduct ions for amines are [M + H](+) and [M + 77](+), for carboxylic acids [M + 27](+), [M + 59](+) and [M + 77](+), and for amino acids [M + H](+), [M + 13](+), [M + 27](+) and [M + 77](+). Either the adduct ion [M + H](+) or [M + 77](+) was the most abundant ion found for amino acids. The proton affinities of amino acids are noticed to control the formation of the [M + H](+) and [M + 77](+) ions. The relative abundance of [M + 13](+) and [M + 27](+) ions varied for different amino acids being most intense for phenylalanine and aspartic acid. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
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本文报导了采用氩离子激光器来泵浦Rr ̄(3+):YLF晶体,应用声光调制器实现了主动锁模;同时应用振动─高反射平面镜也实现了被动锁模,两种锁模均得到了ps光脉冲。据作者了解这是这种晶体材料的第一次锁模运转。 相似文献
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Alves GA Amato S Anjos JC Appel JA Astorga J Bracker SB Cremaldi LM Dagenhart WD Darling CL Dixon RL Errede D Fenker HC Gay C Green DR Jedicke R Karchin PE Kennedy C Kwan S Lueking LH de Mello Neto JR Metheny J Milburn RH de Miranda JM da Motta Filho H Napier A Passmore D Rafatian A dos Reis AC Ross WR Santoro AF Sheaff M Souza MH Spalding WJ Stoughton C Streetman ME Summers DJ Takach SF Wallace A Wu Z 《Physical review letters》1996,77(12):2392-2395
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LL Handley R Azcón Ruiz Lozano JM CM Scrimgeour 《Rapid communications in mass spectrometry : RCM》1999,13(13):1320-1324
It has long been evident that plant (15)N chiefly reflects the processes which fractionate (15)N/(14)N rather than the (15)N of plant N source(s). It has emerged recently that one of the most important fractionating processes contributing to the whole plant (15)N is the presence/absence, type or species of mycorrhiza, especially when interacting with nutrient deficiency. Ecto- and ericoid mycorrhizas are frequently associated with (15)N-depleted foliar (15)N, commonly as low as -12 per thousand. As shown by the present study, plants having no mycorrhiza, or those infected with various species of arbuscular mycorrhiza (AM)-forming fungi, interact with varying concentrations of soil nitrogen [N] and moisture to enrich plant (15)N by as much as 3.5 per thousand. Hence the lack of a mycorrhiza, or variation in the species of AM-forming fungal associations, can account for about 25% of the usually reported variations of foliar (15)N found in field situations and do so by (15)N enrichment rather than depletion. Copyright 1999 John Wiley & Sons, Ltd. 相似文献