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991.
We used an immunofluorescence technique to investigate the effects of varying light regimes on ribulose 1,5-bisphosphate
carboxylase/oxygenase (Rubisco) in individual cells of the chlorophyte Dunaliella tertiolecta Butcher. These studies were carried out between September 1995 and February 1996. The population was heterogeneous with respect
to Rubisco localization in the pyrenoid, i.e. in some cells Rubisco staining was highly concentrated in the pyrenoid while
in others it was evenly distributed throughout the chloroplast stroma. When light intensity was varied sevenfold, the fraction
of the cell population that displayed distinct Rubisco staining in the pyrenoid (PR-index) was correlated with light intensity,
although the average Rubisco abundance per cell or per total cellular protein appeared fairly constant. In darkness, or when
treated with 3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU), the PR-index decreased markedly during the first 4 and 3 h,
respectively, and then remained at low levels, while the cell division cycle progression remained unaffected. We conclude
that D. tertiolecta probably possesses an adaptive mechanism, i.e. the redistribution of Rubisco between the pyrenoid (probably the active site
of Rubisco activation and CO2 fixation) and the stroma (probably a reservoir of deactivated Rubisco that is readily available for transport to the pyrenoid
and activation), to respond to variations in irradiance or photosynthetic inhibition. Our results also suggest that this mechanism
is insensitive to slight variations in growth irradiance and to seasonal changes in photoperiod and temperature.
Received: 19 August 1996 / Accepted: 12 September 1996 相似文献
992.
993.
994.
以由地洛试剂为氧化剂,用分光光度法测定染料废水中对氨基酚的含量,进行了波长,贝特洛试剂用量及显色时间等分析条件的选择。精密度和准确度实验结果表明,该准确,快速,可用于染料废水中对氨基酚的测定。 相似文献
995.
996.
农业作为国民经济的基础,是生态文明的重要内容,其文明程度直接体现生态文明程度.生态文明建设给农业经营提出了更高的要求,也为农业生产的发展指明了方向.充分认识生态文明建设与农业生产的关系,加强农业相关人员的生态文明教育和农业环保法制建设,实施更加科学、文明的农业经营方式将对促进农业的可持续发展和生态文明建设发挥积极的作用. 相似文献
997.
998.
Improvements of nano-SiO2 on sludge/fly ash mortar 总被引:1,自引:0,他引:1
Sewage sludge ash has been widely applied to cementitious materials. In this study, in order to determine effects of nano-SiO(2) additives on properties of sludge/fly ash mortar, different amounts of nano-SiO(2) were added to sludge/fly ash mortar specimens to investigate their physical properties and micro-structures. A water-binding ratio of 0.7 was assigned to the mix. Substitution amounts of 0%, 10%, 20%, and 30% of sludge/fly ash (1:1 ratio) were proposed. Moreover, 0%, 1%, 2%, and 3% of nano-SiO(2) was added to the mix. Tests, including SEM and compressive strength, were carried out on mortar specimens cured at 3, 7, and 28 days. Results showed that sludge/fly ash can make the crystals of cement hydration product finer. Moreover, crystals increased after nano-SiO(2) was added. Hence, nano-SiO(2) can improve the effects of sludge/fly ash on the hydration of mortar. Further, due to the low pozzolanic reaction active index of sludge ash, early compressive strengths of sludge/fly ash mortar were decreased. Yet, nano-SiO(2) could help produce hydration crystals, which implies that the addition of nano-SiO(2) to mortar can improve the influence of sludge/fly ash on the development of the early strength of the mortar. 相似文献
999.
1000.
退化土地评价及其生态重建方法研究 总被引:4,自引:0,他引:4
本文系统分析了退化土地评价研究的历史和方法,总结了退化土地的主要类型、分布和形成机理,最后概述了退化土地重建领域的研究进展。 相似文献