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LIGHT REQUIREMENTS FOR THE ENHANCED SYNTHESIS OF A PLASTID mRNA DURING SPIRODELA GREENING 总被引:1,自引:0,他引:1
A plastid mRNA (5 × 105 mol wt) appears as a burst 3 h after white light greening of steady state dark grown plants of Spirodela oligorrhiza. In this species, chlorophyll synthesis begins after 12 h. The light requirement is different from the pulse of far-red reversible red light required to abolish the lag of chlorophyll synthesis in many species, including Spirodela. Continuous high energy far-red is not stimulatory. When the illumination is not continued throughout the time of incorporation, the stimulation is minimal. Low energy blue and red light are stimulatory, and green and far-red light are ineffectual. Blue light was > 5 times as effective as red light at many dose levels. Illumination with 3 × 1017 quanta/m2/s (50pEm/cm2/s) blue light at 476 nm gave about half maximum stimulation. 相似文献
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VARIATION IN THE RATES OF SYNTHESIS AND DEGRADATION OF PHYTOCHROME IN COTYLEDONS OF CUCURBITA PEPO L. DURING SEEDLING DEVELOPMENT 总被引:3,自引:0,他引:3
E. Schäfer 《Photochemistry and photobiology》1978,27(6):775-780
Abstract— The time courses for Pr appearance, Pr disappearance and Pfr destruction have been analysed in cotyledons of Cucurbita pepo L. after different preirradiation programs. In etiolated seedlings the rate of Pr appearance is low in young seedlings reaching a maximum in 3.5–5 day old seedlings then decreasing rapidly with increasing age. The rate of Pfr destruction is very low in young seedlings, increases rapidly up to the 4th day and then remains almost constant. The disappearance of Pr becomes significant for seedlings older than 45 days. These reactions seem not to be influenced by short preirradiations. However, after prolonged preirradiation, a degree of control of P, appearance and/or disappearance by the "internal clock appears to be operative. 相似文献
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硅藻土-莫来石复合陶瓷膜支承体的制备及表征 总被引:9,自引:1,他引:8
利用硅藻土微粒骨架孔作为孔道,以莫来石为硅藻土微粒的粘连剂,采用溶剂-胶胶-烧结技术制得了硅藻土-莫来石复合陶 膜支承体,这种膜支承体孔径集中于2μm左右,孔隙率约为0.4,耐中度大于4.5MPa,是一种品质优良的膜支承体材料,在综合考察基制造工艺过程和条件的基础上,提出了一个新的复合陶瓷膜支承体烧制模型。 相似文献
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本文合成了Keggin结构的[GeW11O39(Ru·OH2)]5-和[BW11O39(Ru·OH2)]6-杂多阴离子的四丁基铵盐。通过紫外-可见、红外光谱、核磁共振、顺磁共振和循环伏安法对上述化合物进行了表征。结果表明Ru(Ⅲ)处于一个八面体弱场中,Ru(Ⅲ)的顺磁性和核四级矩对 183W的化学位移和强度有明显的影响,其电化学还原与W(Ⅳ→Ⅴ)相关。Ru(Ⅲ)填充了缺位杂多阴离子的空位,但仍然保持Keggin结构。 相似文献
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FLUORESCENCE AND THE STRUCTURE OF PROTEIN—XX. FLUORESCENCE OF 3-AMINOTYROSINE AND OTHER AMINOPHENOLS
ROBERT W. COWGILL 《Photochemistry and photobiology》1971,13(3):183-194
Abstract— –The fluorescence of 3-NH2 tyrosine and of simpler isomeric aminophenols was observed in aqueous solution at room temperature. Marked changes in both emission spectrum and fluorescence efficiency were observed upon change of pH and solvent composition. An explanation for the observed behavior is offered on the basis of two effects. First, peculiarities in the emission spectra were accountable in terms of proton dissociation from the cationic amino group in the excited singlet state so that emission characteristic of the free base was observed even in acidic solutions. Second, the unexpectedly low fluorescence efficiency from the free base was shown to result from quenching by the aqueous solvent. The relevance of these studies for the fluorescence of 3-NH2 tyrosyl groups in proteins is discussed briefly. 相似文献
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本文合成了单硫代二苯甲酰甲烷(HTDBM)和三价希土离子及路易斯碱(Q)的Ln(TDBM)_4QH型配合物(Ln=除Ce外的La~Lu,Q=二乙基胺)。测定了它们的摩尔电导值、红外光谱,可见—紫外光谱,核磁共振谱.观察到配合物是通过硫原子、氧原子同时与Ln~(3+)离子配位.Ln-O键强于Ln-S键。在Nd~(3+)、Pr~(3+)、Ho~(3+)、Er~(3+)离子的该类配合物的可见吸收光谱中发现超灵敏跃迁现象。讨论了题述配合物作为核磁共振化学位移试剂的可能性. 相似文献
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Kuo Chu Hwang David Mauzerall Richard W. Wagner Jonathan S. Lindsey 《Photochemistry and photobiology》1994,59(2):145-151
A one flask synthesis of cis -substituted amphipathic porphyrins is reported. These porphyrins were used to study electrostatic effects on photoinduced electron transfer across the lipid bilayer-water interface. A neutral porphyrin undergoes only dynamic interfacial electron transfer reactions irrespective of charge of the acceptor, although ionic strength effects indicate a negative charge on the porphyrin donor species. A dianionic porphyrin forms an interfacial static complex with a dicationic electron acceptor, methyl viologen, at low ionic strength. The electron transfer rate within the complex is slow, 105 ∼ 106 s-1 , which is attributed to a near orthogonal orientation between the donor and the acceptor ∼ orbitals. 相似文献
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Abstract— The daily changes in spectral energy distribution of natural daylight, with special reference to the red and far-red wayelength bands, are outlined. The effects of solar elevation and sky condition are described. The changes in the proportions of red and far-red radiation in daylight which occur at sunrise and sunset are discussed in relation to the possible function of phytochrome in photoperiodic timing. 相似文献
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可溶性共轭聚席夫碱的合成、表征及电性能 总被引:7,自引:0,他引:7
本文以对苯二胺分别与乙二醛、丁二酮、3,4-己二酮和4,5-辛二酮缩聚合成了四种主链结构相同而侧基各异的新颖共轭性聚席夫碱.采用红外光谱和元素分析等方法对聚合物进行了表征.发现带有侧烷基的共轭性聚席夫碱能溶于一般有机溶剂;不同侧基的聚席夫碱溶解性是:两基聚席夫碱>乙基聚席夫碱>甲基聚度夫碱.测定了四种共轭聚席夫碱的本征导电率及其与温度的关系,结果表明,聚合物具有半导体性质.当聚合物以碘掺杂后,导电率可从10-11-10-12S/cm增加到10-3-10-4S/cm.探讨了共轭聚合物的侧基取代对掺杂后导电性的影响. 相似文献
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合成了新的十一个2-(N-十六烷基氨基甲酰基)-8-羟基喹啉(C26H39N2O2,简写为HL)的配合物[ML2],(M=Mn(Ⅱ)、Co(Ⅱ)、Ni(Ⅱ)、Zn(Ⅱ)、Cd(Ⅱ)、Pd(Ⅱ)、Mg(Ⅱ)和Ca(Ⅱ))、[ML2Cl(H2O)4](M=La(Ⅲ)、Ga(Ⅲ))和[CuLCl],并经元素分析、摩尔电导、磁性和红外光谱所表征。红外光谱表明:配合物是以三齿形式与金属离子配位。配合物中C-O键伸缩振动频率与中心金属离子的相对原子质量或中心离子的电离势呈双线性关系。 相似文献
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J. P. Reyftmann E. Kohen P. Morliere R. Santus C. Kohen W. F. Mangel L. Dubertret J. G. Hirschberg 《Photochemistry and photobiology》1986,44(4):461-469
Microspectrofluorometry on single living cells reveals that the primary effects of porphyrin-photosensitization on membranes results in the production of fluorescent lipofuscin-like pigments implying important lipid photoperoxidation. These fluorescent products (max 450 nm) can also be formed in the dark after the irradiation of the cell. Their formation is abolished not only by crocetin and Tigason, two long-chain polyenes, but also by chloroquine. The latter, although a lysosomotropic drug, cannot inhibit the photosensitized permeation of lysosomal membranes which occurs at the beginning of the irradiation as shown by the splitting of fluorogenic substrates by lysosomal proteinases or by β-galactosidase when added before or after irradiation. 相似文献