Lethal Effects of Elevated pH and Ammonia on Early Life Stages of Hybrid Striped Bass

Hybrid striped bass larvae (striped bass, Morone saxatilis, ♀ x white bass, M. chrysops, ♂) are often stocked into fertile culture ponds. High rates of photosynthesis may result in elevated pH which can be lethal to fry and can affect the toxicity of ammonia. Six-hour static toxicity tests were performed on hybrid larvae of various ages to determine the toxicity of elevated pH and the effects of elevated pH on ammonia toxicity. Six-hour mortality threshold pH's with no measurable ammonia were estimated for various age larvae and found to be between pH's 9.8 and 10.2 for D2 (Dl is day of hatch), between 9.0 and 9.4 for D4, between 8.8 and 9.2 for D13, and between 9.2 and 9.4 for D20 fish. The addition of 0.7% NaCl had no effect on the toxicity of elevated pH to D2 or D4 fish but caused a significant reduction in the mortality of Dl3 and D20 fish exposed to high pH. The tolerance to elevated pH decreased as ammonia concentration increased. Sub-lethal un-ionized ammonia concentrations increased the toxicity of elevated pH, suggesting an interaction of pH and un-ionized ammonia toxicity.     

谷氨酸铜对罗非鱼和草鱼生长性能血清生化指标和体组成的影响

为研究谷氨酸铜制剂对罗非鱼、草鱼的生长性能、血清生化指标和鱼体组成的影响，选用180尾罗非鱼、135尾草鱼，分别随机分为3个处理组，每组3个重复，每个重复20或15尾。在基础饲料中添加五水硫酸铜作为对照组（10 mg/kg），试验组添加谷氨酸铜（高、低剂量组分别为10、5 mg/kg，按铜离子计），饲养8周。结果表明：与对照组相比，谷氨酸铜高、低剂量组罗非鱼的增重率分别提高3.9%和5.8%，草鱼的增重率分别提高4.0%和5.9%；罗非鱼特定生长率分别提高1.9%和3.3%，草鱼分别提高2.5%和3.5%；罗非鱼和草鱼的平均饵料系数分别降低7.6%和3.7%。两种鱼的血清生化指标及体组成各试验组间均无显著差别（P＞0.05）。由此可见，日粮中添加适量谷氨酸铜可提高鱼体的生长性能，且效果优于五水硫酸铜。     

不同阶段饲养法对肉鸡生产性能的影响

为研究阶段饲养法对肉鸡生产性能的影响，试验选择1日龄罗斯308肉鸡135只，随机分为3组，每组3个重复，每个重复15只。Ⅰ～Ⅲ组分别采用两阶段、三阶段、六阶段饲养法。饲养42 d，测定各生产性能指标。结果表明：试验全期，Ⅱ组日增重较Ⅰ组显著提高（P＜0.05），料重比显著降低（P＜0.05）。由此可见，三阶段饲养法效果最好。     

独立院校大学生学风监管机制研究

建立养成大学生优良学习习惯的学风监管机制,是高校学风建设的重要方法之一。马克思主义＂质量互变规律＂是建立大学生学风监管机制的理论基石,思想政治教育调控理论是建立大学生学风监管机制的实践运作原理。     

Histopathology of Hematopoietic Tissue in Channel Catfish,Ictalurus punctatus,with Anemia

Outbreaks of anemia (CCA) in channel catfish, Ictalurirs punctatus, in Mississippi occur predominantly during spring and fall. Between October, 1990 and May, 1991, twenty-seven cases of CCA were submitted to the Mississippi Cooperative Extension Service-College of Veterinary Medicine Fish Diagnostic Laboratories. Histologic lesions were identified in the head and trunk kidneys of all affected fish. The head kidney contained less than 25% immature hematopoietic tissue in 3 of 22 cases (14%). 25-50% immature hematopoietic tissue in 7 of 22 cases (32%), and greater than 50% immature hematopoietic tissue in 12 of 22 cases (54%). The trunk kidney contained less than 25% immature hematopoietic tissue in 5 of 27 cases (18%), 25-50% immature hematopoietic tissue in 15 of 27 cases (56%), and greater than 50% immature hematopoietic tissue in 7 of 27 cases (26%). The histopathologic findings noted in cases of CCA from Mississippi affect primarily the hematopietic tissues of the head and trunk kidneys.     

重庆市万州区1年生尾巨桉生长情况调查

通过对重庆市万州区营造尾巨桉(3229品系)的调查结果表明,该树种在该区域的适应性和速生性较强,可进一步扩大种植范围,在万州区乃至三峡库区具有一定的发展前景。     

道德思维的逻辑结构与形态演进：规范、语言与共识

道德思维是人类思维活动中的重要方式和特殊样式，人的道德行为方式在很大程度上受道德思维水平支配和制约。道德思维作为伦理学研究的主要内容，随着伦理学理论形态范式的演进和嬗变，相应地发生着历时性的范式转向和共时性的理论融合。探究道德思维的逻辑关系考察、结构要素分析和理论形态演进，可以廓清道德思维从本体论到认识论再到实践论的理论主题的转换和研究方法的更新。道德思维从综合性思维到分析性思维再到反思性思维的演进历程，有助于深刻理解道德规范、道德语言和道德共识之于人类生活和社会发展的理论价值和实践意义。     

AM真菌对油茶生长和抗旱性的影响

AM（Arbuscular mycorrhiza）真菌能够促进植物生长，提高植物的抗逆性。AM真菌对油茶生长和抗旱性的影响的研究表明：接种AM真菌促进了油茶生长，改善了油茶叶片水分状况，增强了叶片细胞质膜的稳定性，使可溶性糖含量增加。     

小花忍冬硬枝扦插影响因素分析

小花忍冬是观赏性和抗逆性兼具的优良树种之一。为了解决其种子繁殖子代分化变异大的问题,结合小花忍冬特性,通过不同基质、激素及不同浓度的处理,对其进行了硬枝扦插试验。结果表明：基质种类、激素种类、激素浓度都直接影响其扦插成活率,激素种类直接影响地下根系的生长量。其中,使用珍珠岩︰沙子=1︰2、NAA、100 mg/L组合,...     

高寒草地西北针茅生长发育特征及与气象因子的关系

利用1999～2009年连续11年的定位观测数据,研究了高寒草地西北针茅的生长发育特征与气象因子的关系。结果表明,在3月中旬,如果气温升高,返青日会推迟,这主要因为高温促使土壤水分蒸发,而土壤干旱阻碍返青;返青后,如果≥0℃的积温不足或累计日照时数不足,针茅的抽穗期会推迟;开花期的当日平均气温在10～20℃,如果抽穗-...