森林认证与系统思想

森林认证是缓解全球森林退化、实现可持续发展战略的重要手段之一。它包括森林经营认证和森林产品认证。森林认证将影响到世界森林资源、各国林业发展以及生态、经济和社会。森林认证是一项复杂的系统工程,涉及国家政策和国民经济的方方面面。只有利用系统理论,才能更好分析论证在中国特定条件下的森林认证系统;在系统思想指导下,找出我国森林认证的关键要素、主要子系统和最优结构,才能发挥森林认证体系的最佳功能。

Effects of aniracetam on extracellular levels of transmitter amino acids in the hippocampus of the conscious gerbils: an intracranial microdialysis study

The effects of aniracetam on extracellular amino acid levels in the hippocampus of conscious gerbils, with or without transient cerebral ischemia/reperfusion, were measured by microdialysis and reverse phase-high performance liquid chromatography. Increased extracellular levels of aspartate and glutamate that were observed in the hippocampus of conscious gerbils during transient global forebrain ischemia were reversed by aniracetam. In contrast, the level of extracellular gamma-aminobutyric acid was increased, while taurine was maintained at a higher level than other amino acids by administration of aniracetam (100 mg/kg, p.o.) 60 min before ischemia. Further, in contrast to ischemic animals, administration of aniracetam (100 mg/kg, p.o.) enhanced the release of glutamate and aspartate in the normal gerbil hippocampus. The results suggest that these effects might be due to a partial calcium agonist activity of aniracetam, and that the effects of aniracetam on amino acid levels might be a mechanism of protection against delayed neuronal death in the ischemic hippocampus, thereby improving memory dysfunction induced by ischemia/reperfusion. (C) 2003 Elsevier Science Ireland Ltd. All rights reserved.

6种常用渔药对厚颌鲂鱼苗的急性毒性试验

在水温29~30℃条件下,用硫酸铜与硫酸亚铁合剂(比例5:2)、高锰酸钾、晶体敌百虫、强氯精、溴氯菊脂、甲醛共6种药物对厚颌鲂(Megalobrama pellegrini)鱼苗进行急性毒性试验。试验结果显示,6种药物48h的半致死浓度分别为5.78、6.50、4.90、2.55、0.042、120mg/L,安全浓度分别为0.445、0.528、0.268、0.190、0.003、7.500mg/L,厚颌鲂鱼苗对药物敏感性比一般鱼类高,实际用药时应根据具体情况确定用药时间和用药量,溴氯菊脂不宜作为治疗药物