低氧低二氧化碳对大鼠脑血流的调节作用

低氧下脑血流与急性高原病有关,许多研究已证明,低氧不适应者的ＣＢＦ明显高于低氧适应者,而高原世居者则低于海平正常值。低氧下低动脉血二氧化碳分压有对抗低氧扩血管及降低ＣＢＦ的作用。因此研究低氧下低ＰａＣＯ２对ＣＢＦ的调节作用对于研究急性高原病的防治及其机理分析具有重要意义。本项研究目的：（１）揭示低氧下低ＰａＣＯ２与ＣＢＦ之间的关系;（２）通过增加通气量使ＰａＣＯ２下降至合适水平,以保护脑血流维持在     

Diatom communities of acidic mountain streams in Poland

A comparison has been made of the species composition of diatom communities developing in acidic Polish mountain streams which flow over calcium-poor substrates: sandstones in the Silesian Beskid (section of the Western Carpathians), the witokrzyskie Mts, and over granite in the Karkonosze range (in the Sudetic Mts). The number of taxa and diversity of the diatom assemblages decreased along a decreasing pH gradient. The correlation between pH and the number of taxa was positive and significant (r ² = 0.69, p < 0.005). A small number of species (< 20) and low diversity were found in the communities developing in strongly acidic streams such as in the witokrzyskie Mts with pH 4.1–5.2, and in the Silesian Beskid with pH 3.5–4.0. In the stream of the Karkonosze Mts, with pH 5.2–6.0, the communities were characterized by their greater number of species and higher diversity.Acidobiontic and acidophilous diatoms were generally dominant. The pH-indiferent forms were less abundant, and their proportion increased above pH 5.0. Eunotia exigua, E. paludosa var. trinacria, E. tenella and Pinnularia subcapitata dominated in streams with the lowest pH, while E. exigua, E. sudetica and Achnanthes kryophila predominated in a stream with water pH above 5.2. Eunotia exigua, a common acidobiontic species was present in all the examined communities, and was a strong dominant in waters of pH 5.0. A corresponding decrease in abundance of E. exigua was observed with an increase in pH.     

Short-term effects of a large dam decommissioning on biofilm structure and functioning

Aging dams and the rising efforts to restore stream ecosystems are increasing the number of dam decommissioning programs. Although dam decommissioning aims at improving in-stream habitat, biodiversity, and ecosystem functioning in the long term, it might also cause ecological impacts in the short term due to the mobilization of the sediment accumulated in the reservoir. Benthic biofilm in particular can be impaired by episodes of high turbidity and scouring. We conducted a multiple before-after/control-impact experiment to assess the effects of the drawdown of a large dam (42 m tall), a first step to its decommissioning, on biofilm structure (biomass and chlorophyll-a) and functioning (metabolism, nutrient uptake, and organic matter breakdown). Our results show that the reservoir drawdown reduced the autotrophic biofilm biomass (chlorophyll-a) downstream from the dam, which in turn lowered metabolism. However, nitrogen and phosphorus uptake by the biofilm was not affected. Organic matter breakdown was slower below the dam than in nearby undammed reaches before and during drawdown. All drawdown effects quickly disappeared and reaches downstream from the dam approached values found in nearby undammed reaches. Thus, our results indicate that the effects of reservoir drawdown on stream biofilms exist but may be small and disappear rapidly.     

庐山野生观赏植物资源多样性及持续利用对策

庐山是我国著名的风景旅游和避暑胜地,也是我国中亚热带北缘植物多样性的宝库．本文在广泛调查、收集、整理的基础上,研究了庐山野生观赏植物资源多样性特征、分布、类型及其配置．本区分布有野生观赏植物５２８种,隶属于１１５科２９０属,其中乔木类１３８种,灌木类１４０种,藤木类５２种,草本类１９８种．并根据开发与保护现状对庐山野生观赏植物资源多样性的持续利用提出了切实可行的对策．     

一种模拟高原低氧复合冷冻的简易动物实验舱

以氮稀释法使舱内氧含量维持实验模拟高度,以普通冰箱制冷系统维持舱内恒温,以多功能低温浴槽作为致冻装置。该舱可于２０ｍｉｎ内升至模拟６０００ｍ高度,每次可供１６只大鼠作高原冻伤实验。实验期间高度恒定于６０００±２００ｍ,舱温２１±１℃。相对湿度５５％±１５％,冷冻液－２５．０±０．５℃。该舱结构简单、使用方便,可在实验室中模拟高原条件进行冷冻实验研究。由于不使用人体减压舱,不仅避免了减压缺氧对实验人员的不利影响,也减少了实验消耗。     

贺兰山不同生境旱生灌木的解剖学研究

贺兰山荒漠地带三种不同基质生境的２０种旱生灌木的营养器官的比较解剖学研究表明：其共同特点是叶片的表面积／体积的比值小,叶表具厚的角质层、表皮毛,气孔下陷、并具孔下室,叶向中栅栏组织发达;轴器官中木栓层细胞层数多,皮层较厚,机械组织发达,木薄壁组织及髓部细胞的细胞壁术化加厚,根内都具周皮、木质部的导管分子大小不一、频率较高。此外,根、茎、叶中普遍存在粘液细胞和草酸钙结晶,部分植物的根和茎内有异常维管组织。这些结构特征都与早生环境相关,而不同基质生境中生长的植物尚存在一定差异。     

湖北、河南、安徽三省大别山区地理新分布植物

湖北、河南、安徽三省大别山区地理新分布植物何家庆（安徽大学生物系合肥２３００３９）关键词大别山区,种子植物,地理新分布ＴＨＥＮＥＷＧＥＯＧＲＡＰＨＩＣＡＬＤＩＳＴＲＩＢＵＴＩＯＮＯＦＳＰＥＲＭＡＴＯＰＨＹＴＥＩＮＤＡＢＩＥＳＨＡＮＴＨＥＲＥＧＩＯＮＳ...     

Resistenzphysiologische Grundlagen der evolutiven Kälteakklimatisation von Sproßpflanzen

Gradations in cold resistance of plants with different latitudinal and altitudinal distribution, and the various categories of chilling and freezing resistance are hypothesized to be evolutionary steps of adaptive responses to increasing low temperature stress and annual seasonality. The gradual lowering of the critical phase transition temperature of biomembrane lipids, the capacity of persistent supercooling of tissues, and the development of a dormancy linked freezing-tolerance are considered to be essential mechanisms resulting in improved acclimatation to low temperature climates.