东北梅花鹿优化育种规划中育种目标的确定

讨论了东北梅花鹿依据经济指标确定育种目标的问题 ,以及在东北梅花鹿育种规划中 ,应如何挑选在综合育种目标中的生产性状及其对应的选择性状。并着重介绍了应用综合育种值作为数量化育种目标的方法。指出在确定以茸用为主的东北梅花鹿育种目标时 ,除了主要考虑茸用性状外 ,还应适当地考虑繁殖和使用寿命等性状 ,同时对于直接影响茸鹿生产效益的直接性状和次级性状不容忽视。     

区域畜禽环境承载力核算方法研究与应用

针对畜禽养殖区域布局不合理,科学、实用的环境承载力核算方法欠缺的问题,本研究在畜禽土地承载力核算方法的基础上,综合考虑水环境容量和经济社会发展等因素,构建了基于作物养分需求及水土环境多要素的畜禽环境承载力核算模型,确定了模型参数取值,形成了畜禽环境承载力核算方法。以湖南省为例对核算方法进行应用验证,核算出湖南省畜禽环境承载力为6 113.16万头当量生猪。经与相关研究成果比对分析,认为该核算方法优于我国当前广泛采用的土地承载力核算方法,表明该核算方法具有较强的科学性与实用性,对各地科学合理的测算畜禽养殖环境承载力,确保畜牧业与环境协调发展具有指导意义。     

新中国以来我国学校体育目标的衍变与存在问题

为了使我国学校体育目标与时代发展相适应、反映时代的要求、对学校体育课程与教学实践起到引领作用,采用文献资料、专家问卷调查以及思辨等方法,对新中国成立以来我国各个时期学校体育目标的发展过程进行研究,历史地、辩证地分析60年来我国学校体育目标的发展、衍变脉络;总结出不同时期我国学校体育目标的特点、对我国学校体育实践的影响;通过科学分析提出了我国学校体育目标存在的问题和思考。     

Spatial prediction of soil nutrient in a hilly area using artificial neural network model combined with kriging

It is widely recognized that using correlated environmental factors as auxiliary variables can improve the prediction accuracy of soil properties. In this study, a radial basis function neural network (RBFNN) model combined with ordinary kriging (OK) was proposed to predict spatial distribution of four soil nutrients based on the same framework used by regression kriging (RK). In RBFNN_OK, RBFNN model was used to explain the spatial variability caused by the selected auxiliary factors, while OK was used to express the spatial autocorrelation in RBFNN prediction residuals. The results showed that both RBFNN_OK and RK presented prediction maps with more details. However, RK does not always obtain mean errors (MEs) which were closer to 0 and lower root mean square errors (RMSEs) and mean relative errors (MREs) than OK. Conversely, MREs of RBFNN_OK were much closer to 0 and its RMSEs and MREs were relatively lower than OK and RK. The results suggest that RBFNN_OK is a more unbiased method with more stable prediction performance as well as improvement of prediction accuracy, which also indicates that artificial neural network model is more appropriate than regression model to capture relationships between soil variables and environmental factors. Therefore, RBFNN_OK may provide a useful framework for predicting soil properties.     

氮素形态对植物生长影响的研究进展

铵态氮和硝态氮作为植物从土壤中吸收的主要无机态氮素,对植物的形态学特征以及生理过程具有不同的影响。从植物对不同形态氮素的吸收利用机制,氮素形态调控植物养分吸收、根系发育、光合生理、产量与品质形成及氮转运蛋白基因表达等方面进行了综述,阐述了氮素形态调控植物生长的机理,并提出了氮素形态研究中需要进一步阐明的问题。     

三河牛目标性状边际效益研究

【目的】三河牛是1983年验收的中国自主培育的乳肉兼用牛品种,因起源于内蒙古呼伦贝尔市三河地区而得名,具有耐粗饲、宜牧、抗寒、适应性强的特点。研究旨在估计三河牛目标性状的边际效益,为制定三河牛育种规划提供基础。【方法】依据内蒙古谢尔塔拉种牛场三河牛中心产区2011年的生产和育种数据,参照奶牛和肉牛营养需要获得三河牛的生产性能、市场经济、营养学方面的参数,根据三河牛生产和育种体系,确定三河牛育种目标性状,以效益方程法建立三河牛的生物经济利润模型,计算三河牛乳用性状、肉用性状、功能性状的边际效益,并对影响经济效益的各个因素进行了敏感性分析。【结果】（1）确定了三河牛10个育种目标性状,包括3个乳用性状（产奶量,乳蛋白率和乳脂率）,3个肉用性状（初生重,育肥期日增重和屠宰率）和4个功能性状（首次产犊日龄,产犊间隔,体细胞数和母牛使用年限）：（2）牛群规模固定时,三河牛的总效益为4 808.26元。对收益进行分类,产奶和淘汰母牛的收益分别占总收益的67.08%和7.8%,育肥牛的收益占总收益的20.58%。成本方面,可变成本占总成本的96.89%,其中饲养费用是影响可变成本的主要因素,青年母牛、泌乳母牛和育肥公牛的饲养成本分别占总成本的45.69%、20.46%和13.15%;（3）以乳成分和质量（乳脂率、乳蛋白率、体细胞数）定价时,三河牛10个目标性状的边际效益为：产奶量（kg）2.26元、乳脂率（%）40.48元、乳蛋白率（%）61.39元、体细胞数-231.52元、初生重（kg）6.19元、育肥期日增重（g•d-1）1.39元、屠宰率（%）76.70元、使用寿命（天）0.25元、首次产犊日龄（天）-1.62元、产犊间隔（天）-2.71元;（4）乳用性状、肉用性状、功能性状的相对经济权重比例为62﹕14﹕22,近似于3﹕1﹕1的比例。（5）牛奶价格提高10%,产奶量和产犊间隔的边际效益分别增加0.29元和0.17元;牛肉价格提高10%,初生重、育肥期日增重、屠宰率、产犊间隔的边际效益分别增加0.81元、0.15元、7.86元,使用年限的边际效益降低0.03元;饲料价格提高10%,产奶量、乳脂率、乳蛋白率、初生重、首次产犊日龄、育肥期日增重的边际效益分别降低0.05元、0.58元、0.34元、0.21元、0.16元、0.01元,产犊间隔和生产寿命的边际效益分别增加0.88元、0.06元。【结论】市场价格的变动对三河牛乳用性状和肉用性状的边际效益影响较大。研究构建的生物经济利润模型可为在中国实施兼用牛选育提供参考,为制定三河牛育种体系的育种目标提供依据。     

Numerical analysis on the performance of spiral antennas

The surfaces of the Planar Spiral Antennas and Conical Spiral Antennas are analyzed with planar triangle. The surface currents of the antennas are solved by using the Method of Moment (MoM) based on the RWG basis function. The input impedance, directivity, gain, radiated power and radiation field of the antenna can be found. The results indicate that, in very wide frequency band, the value of the input impedance equals to the theoretical value of Self-Compensated antennas (in agreement with Babinet-booker' principle), which is,188.5 ohm , the half of the wave impedance of free space, while the directivity, gain and radiated power are stable within the frequency band. When the antenna is driven by the signal of derivative Gaussian pulse, the radiating electric field waveform is obtained by the Fourier transform. When the spiral antenna is used as the pulse radiation antenna, the waveform of the radiation electric field shows the characteristics of the Gaussian quadratic differential.     

森林覆盖率计算标准的变化对云南省宏观规划目标的影响

森林覆盖率是宏观规划的重要指标之一,国家林业局在2003年颁布了新的森林覆盖率计算方法,由于标准的变化,导致森林覆盖率宏观规划目标值的变化．文章阐述了新旧森林覆盖率标准的变化和关系,以云南为例,计算不同时期森林覆盖率的同标准指标,分析云南省森林覆盖率的规划目标,2015年宜为53％,2020年宜为57％,极限目标为63％．     

A Land Use Model for Urban Rail Station Area Planning Based on TOD Strategy

Transit oriented development (TOD) presents a sustainable urban development strategy by creating an efficient integration of land use and public transit. A TOD planning model for the land use of urban rail station area was explored by means of a multiple objective mathematical programming model. Three objectives were considered: encouraging transit system volume, promoting livable communities, and balancing land use. The model can easily be solved by transforming it into a linear multi programming problem. The Xujiahui rail rapid transit station area in Shanghai is chosen as case study to illustrate the model application and planning results. The result indicates that the model would be efficient in practice.     

农林类院校培养全日制农民大学生的方式探讨

从农民大学生培养目的出发,分析了农林类院校培养农民大学生的优势,在培养方式上提出应重视农民大学生政治素养培养;基础课程实施实例式授课;注重专业实践能力培养,设置开放式的专业教学;加强中国农村现状与发展模式的教育;注重培养农民大学生控制农业产业链末端的能力;引导农民大学生积极参与校园文化活动,发挥农林类院校在培养农民大学生方面的优势,通过全日制农民大学生的培养为社会主义新农村建设输送更多的高素质建设者。