高校图书馆新管理模式影响因子初探

通过对图书馆新管理模式影响因子的研究,分清这些影响因子有哪些,并揭示它们和新管理模式之间的内在联系,对现实工作具有积极的指导意义。     

夏大豆植株干物质积累数学模拟研究

对夏大豆濉科8号、中黄13两个品种从出苗至成熟共15次测定了植株质量,建立了数学模型。结果表明:植株、茎叶质量呈"慢—快—慢—降"的单峰变化趋势,而籽粒质量呈"慢—快—慢"的S形曲线变化趋势,单株粒重、百粒重则随生育时期呈直线增长趋势。y=ef(t)真实的反映了出苗、始花、终花至成熟期植株、茎叶质量变化。     

Application of the Cropping System Model (CSM)‐CROPGRO‐Soybean for Determining Optimum Management Strategies for Soybean in Tropical Environments

The determination of optimum crop management practices for increasing soybean production can provide valuable information for strategic planning in the tropics. However, this process is time consuming and expensive. The use of a dynamic crop simulation model can be an alternative option to help estimate yield levels under various growing conditions. The objectives of this study were to evaluate the performance of the Cropping System Model (CSM)‐CROPGRO‐Soybean and to determine optimum management practices for soybean for growing conditions in the Phu Pha Man district, Thailand. Data from two soybean experiments that were conducted in 1991 at Chiang Mai University and in 2003 at Khon Kaen University were used to determine the cultivar coefficients for the cultivars CM 60 and SJ 5. The CSM‐CROPGRO‐Soybean model was evaluated with data from two experiments that were conducted at Chiang Mai University. The observed data sets from farmers’ fields located in the Phu Pha Man district were also used for model evaluation. Simulations for different management scenarios were conducted with soil property information for seven different soil series and historical weather data for the period 1972–2003 to predict the optimum crop management practices for soybean production in the Phu Pha Man district. The results of this study indicated that the cultivar coefficients of the two soybean cultivars resulted in simulated growth and development parameters that were in good agreement with almost all observed parameters. Model evaluation showed a good agreement between simulated and observed data for phenology and growth of soybean, and demonstrated the potential of the CSM‐CROPGRO‐Soybean model to simulate growth and yield for local environments, including farmers’ fields, in Thailand. The CSM‐CROPGRO‐Soybean simulations indicated that the optimum planting dates from June 15 to July 15 produced maximum soybean yield in a rainfed environment. However, the planting date December 15 produced the highest yield under quality irrigation. Soybean yield was slightly improved by applying nitrogen at a rate of 30 kg N ha^?1 at planting. Soybean yield also improved when the plant density was increased from 20 to 40 plants m^?2. The results from this study suggest that the CSM‐CROPGRO‐Soybean model can be a valuable tool in assisting with determining optimum management practices for soybean cropping systems in the Phu Pha Man district and might be applicable to other agricultural production areas in Thailand and southeast Asia.     

Coarse woody debris in late-successional Picea abies forests in northern Europe: Variability in quantities and models of decay class dynamics

Coarse woody debris pools and their decay class dynamics were studied in three areas of unmanaged boreal forest in northern Finland, and in the Murmansk and Arkhangelsk provinces in northwestern Russia. The study areas had varying climatic and edaphic conditions, and disturbance histories. Living and dead trees (diameter at 1.3 m height ≥10 cm) were measured in five late-successional Picea abies-dominated stands in each of the three areas. Wood density and time since death were determined from randomly sampled dead P. abies, and their decay class dynamics were modeled using stage-based matrix models.     

不同季节、不同出栏日龄对樱桃谷鸭蛋氨酸需要量的影响

本研究结合生产实践，采用大群生产试验方法，对标准化饲养的2847栋鸭舍，同源樱桃谷商品肉鸭2925万只，按统一饲养方式和管理程序进行生产试验。试验日粮分为前期（1～19d）、中期（20～29d）和后期（30d～出栏）3个阶段，记录各饲养阶段肉鸭的采食量、增重、死亡率。结果表明：春、夏、秋、冬肉鸭氨基酸需要量的析因模型分别为：春季：METR=0．0050BGW＋0．1818W0．75；夏李：METR：O．0055BGW＋0．1554W0．75；秋季：METR=0．0050BGW＋0．1945W0．75；冬李：METR=0．0038BGW＋0．2651W0．75。春、夏、秋、冬四个季节肉鸭的蛋氨酸维持需要分别为每千克代谢体重0．1818、0．1554、0．1945、0．265lg；肉鸭每增重lg体重需要蛋氨酸为0．005、0．0055、0．005、0．0038g。冬季肉鸭摄入的蛋氨酸用于维持需要的量高于其它季节，以夏季最少，春季与秋季肉鸭用于维持需要的蛋氨酸量相当。而肉鸭冬季用于单位增重所需的蛋氨酸最少，其他季节相近。研究同时表明，不同的出栏日龄肉鸭增重lg所需的蛋氨酸量不同，随着肉鸭出栏日龄的延长，肉鸭每增重1g所需的蛋氨酸的需要量逐渐提高。     

杉木人工林南北坡向树高-胸径生长曲线研究

以SPSS为统计工具,将坡向分成南面坡和北面坡,对桃源县杉木人工林的胸径及树高曲线进行了拟合。Compound模型表明:同一胸径下,生长于南面坡的杉木,其树高和生长速度高于北坡;长势好的树木,具有更强的竞争力,生长速度更好。理论分析与实际情况相符,为杉木林的经营与管理提供了科学依据。     

Models for predicting height and diameter of individual trees in young Picea abies (L) karst. stands

Models for predicting height and diameter of individual trees in young Picea abies (L.) Karst. stands were developed. Data collected in a large survey of young forest stands in Sweden (the HUGIN young stand survey) were used in the construction of the models. Models were developed both with and without competition indices included. When constructing the competition indices trees within three metres from the subject tree were regarded as competitors. Functions with competition indices included (distance dependent) will be useful in analyses of the development of stands with different stand structure, whereas functions without competition indices (distance independent) will be useful in systems for long‐term forecasts of yield.     

用突变模型研究森林蓄积的稳定性(英文)

模型构造的方法是以Logistic方程描述生长量 ,假设采伐量为常量且等于生长量时 ,推导出折迭突变模型 .此模型有助于管理层制定管理决策 ,防止森林消亡 .该文又通过曲线采伐模型及Logistic生长模型推导出尖角突变模型 ,这个模型给出了采伐将导致突变发生的敏感区域 ,而且通过模型的滞后性使人们清楚地意识到森林一旦遭受破坏 ,再想恢复需入更大的力量     

松嫩平原玉米带农业生态系统的研究(Ⅱ)——能流模型的建立与可持续性分析

在测试并确定农业生态系统各项参数和状态变量的基础上， 应用数学模型方法建立了松嫩平原玉米带农业生态系统的能流型， 进行了结构与功能的分析， 探讨了不同农业技术模式、土壤有机质和农田产量之间消长的关系。结果认为， 实现农业的持续发展， 应采取有机无机相结合的农业技术体系。