激素与营养液配施对平菇产量及品质的影响

植物激素与营养液配合施用可促进平菇菌丝生长和子实体发育，提高产量，改善商品性状，但却不能增加干物质的积累。对营养成分含量的影响随激素与营养液配方的不同而异。     

The role of ectomycorrhizal fungi in alleviating pine decline in semiarid sandy soil of northern China: an experimental approach

The decline of Mongolian pine (Pinus sylvestris var. mongolica) trees on sandy land in northern China has caused serious ecological concerns. Mongolian pine is an ectomycorrhizal fungus (ECM)-dependent species. Three ECM species (Boletus sp., Lactarius deliciosus and L.sp.) were collected from Mongolian pine plantation stands to test their beneficial effects on Mongolian pine seedlings and their responses to environmental factors such as pH, drought stress and temperature. The results indicated that ECM inoculation significantly increased the rate of ECM colonization and the length of seedling shoots. The three ECM could grow in a pH range from 4 to 7, but did not grow under heavy drought stress (?1.53 MPa). High temperatures (over 37 °C) caused death of ECM. When related to soil pH, soil water content and temperature in the Mongolian pine plantations, water conditions and temperature were unfavorable for ECM growth in surface soil, but suitable in deeper soil. Therefore, it was concluded that the failure of natural regeneration in Mongolian pine plantations might be influenced by the lack of ECM in the surface soil because of high temperatures causing ECM death. Moreover, the majority of the root area is distributed in deeper soil, which alleviates the stresses on ECM development and arrests pine decline; this is beneficial for tree growth.     

白牦牛早期胚胎发育条件的初步研究

研究了卵母细胞质量和体外受精卵培养温度对白牦牛早期胚胎发育的影响。结果表明:白牦牛体外受精时要选择A级质量的卵母细胞,体外受精胚胎发育的最适温度为38℃。为完善白牦牛胚胎的体外生产体系提供了实验依据。     

小麦条锈病的电算模拟研究初报——春季流行的一个简要模型

以日传染率和显症率为主要子模型,组建了一个小麦条锈病田间流行的模拟模型。由第 i 天的露时、露温和病叶上病斑平均面积予测日传染率(Ri)的回归式,和由日平均气温予测显症率(Pji,第 i 天侵入的位点至第 j 天显症的概率)的回归式都是根据田间监测值导出的。品种的相对抗病性也根据试验结果给定参数,通过这些参数对 R 和 P 的修正而组入模型。用未用于组建本模型的田间监测值对模型进行了可靠性检验。在不同品种和气象条件下模拟出的流行曲线大多数与实测曲线大体相符。以气象条件——初始菌量——品种相对抗性病的多种不同的参数组合进行了模拟试验。对这一模拟模型的改进途径和可能的用途也进行了讨论。     

基于键合图理论的动力稳定装置轮轨间动态特性分析

考虑动力稳定装置的轮轨非线性接触、轮轨间的间隙传动、夹钳油缸和水平油缸的等效刚度建立了动力稳定装置动态特性键合图模型.使用分段函数表达式实现了轮轨间的间隙传动.针对不同夹持力对于能量的传递效率与作业效果进行了深入分析与探究,确定了所需最小的水平油缸的推力.     

动物骨粉的应用研究

动物骨头是肉类加工的副产品，由于富含蛋白质，钙、磷等微量元素以及多种维生素等营养成分，具有较高的营养价值，其对动物生产性能的促进作用早已被人们所认知，将其加工为骨粉后用于畜牧养殖已在生产实践中大量利用。了解骨粉的营养特性，掌握骨粉的加工及应用方法，将有助于充分发挥骨粉的营养功效，提高骨粉的利用价值。     

Field evaluation of insect-resistant transgenic Populus nigra trees

The performance of insect-resistant transgenic poplar trees (Populusnigra) expressing a Cry1Ac gene from Bacillus thuringiensis subsp. Kurstaki HD-1 against poplar defoliators was evaluated in the field at the Manas Forest Station in Xinjiang Uygur Autonomous Region during1994–1997. The results showed that the average percentage of highly damaged leaves on the transgenic trees was 10% while that on the control trees in nearby plantations reached 80–90%. The average number of pupae per m² of soil at 20cm depth in transgenic poplar plantation was 18 which was only 20% of that found in the non-transgenic control field. The number of pupae and the leaf-damage on transgenic trees described above are all far below the threshold set for chemical protection measures. The non-transformed poplar trees grown in the same plantation with the transgenic trees were also protected indicating that cross protection occurred between these two kinds of trees. Insect-resistant transgenic poplar trees have a potential application value in afforestation. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effect of stachyose supplementation on growth performance, nutrient digestibility and caecal fermentation characteristics in broilers

1. The objective of this study was to evaluate whether the oligosaccharide stachyose enhances gastrointestinal tract health by fermentation and proliferation of desirable bacteria species and thus affects growth performance and nutrient digestibility in broilers. 2. A total of 432 1-d-old male Arbor Acres (AA) broilers were randomly allocated to one of 6 treatments, with 12 replicate pens per treatment and 6 birds per pen. Chicks were fed a maize-hamlet protein 300 (HP300) basal diet with 0, 4.0, 8.0, 12.0 or 16.0 g/kg stachyose. A sixth diet contained no HP300 but soybean meal (SBM) and provided 8.7 g/kg stachyose and 3.1 g/kg raffinose. The duration of the study was 42 d. 3. Stachyose contents above 12.0 g/kg depressed group body weights, average daily gain and feed/gain but not feed intake during the whole experimental period. Broiler growth decreased linearly and quadratically with increasing stachyose content. No differences were detected between diets supplemented with 12.0 g/kg stachyose and SBM. 4. Nutrient digestibility tended to decrease but not significantly with increasing stachyose. 5. Stachyose content had no significant positive effects on caecal pH, microflora population and the resulting short-chain fatty acid (SCFA) metabolites during the 42 d experiment, with only butyrate differing significantly in the initial period.     

高等农林院校数学建模教育研究与实践

结合1994～1998年甘肃农业大学大学生数学协会数学建模讨论班的实践经验,提出了：高等农林院校数学素质教育内容应包括数学基础教育、数学建模教育、数学建模实践3方面;数学建模教育的形式是“讨论班”;数学建模能力巩固、提高的方式是数学建模竞赛;要培养真正合格的素质型建设人才必须在大学期间参加适当的数学建模实践。并指出只有更多的专家、教授、学者参与到数学素质教育中来,使专业与数学教育真正相结合,数学建模教育乃至数学素质教育的口的才能真正实现。