产前和产后香味剂印迹训练对仔猪断奶后采食偏好的影响及其机理

仔猪断奶后受到心理、营养、环境等多方面的刺激,导致应激反应,影响仔猪的采食量。固体饲粮代替母乳是最大的应激源,通过在母猪饲粮中添加香味剂对仔猪产前和产后进行香味剂印迹训练,使仔猪逐渐喜欢这种气味,降低其对添加相同香味剂饲粮的应激反应,并对有相同气味的饲粮有采食偏好,从而提高仔猪的采食量。本文对产前和产后香味剂印迹训练对仔猪断奶后采食偏好的影响及其机理进行综述,为养猪业相关试验研究提供理论依据。     

特色农产品集群品牌与企业品牌互动机制理论基础述评

该文通过对现有文献的梳理,阐释了特色农产品集群品牌与企业品牌之间互动关系的4大基础理论,即原产地效应、信号理论、品牌理论和生态系统理论,并指出原产地效应和品牌相关理论对特色农产品领域的相关研究具有重要意义。     

三峡大学校园垃圾分类回收现状及回收机制的建立探讨

指出了垃圾分类回收具有重要的意义，有利于资源节约型和环境友好型社会的建设，有利于循环经济的可持续发展。分析了校园垃圾分类回收现状，对建立校园分类回收机制进行了探讨。     

某8V150型柴油机平衡轴优化设计

文章以某8V150柴油机为例,对其平衡轴进行了优化设计,使得双轴平衡机构不但能够100％的平衡二级往复惯性力,而且所设计的平衡轴尺寸小,质量轻,能够有效地消减机体的倾覆力矩,改善了发动机的振动特性,满足了设计要求.     

玉米茎秆抗倒伏遗传的研究进展

茎秆倒伏严重影响玉米产量、品质和机械化收获,是当前玉米生产和育种亟待解决的主要问题之一。加强对玉米茎秆抗倒伏性的研究,对提高品种抗倒伏能力具有重要意义。本文综述了玉米茎秆倒伏的主要影响因素及其遗传特征。茎秆倒伏与茎秆自身的强度密切相关。茎秆强度越高,抗倒伏性越强。茎秆强度受茎秆所处的发育阶段、茎秆内部结构和外部形态,及其细胞壁成分等影响。处于分生组织的茎秆细胞分裂旺盛,较易折断,而进入生殖生长后,茎秆表皮、厚壁组织增厚,维管束发育成熟,对茎秆的支撑作用增强。茎秆细胞壁的主要成分——纤维素、半纤维素、木质素、可溶性糖、无机物等均可提升茎秆强度。目前,研究者借助高通量表型平台,利用玉米连锁群体和自交系群体,采用各种定位方法,鉴定到一系列影响茎秆形态、强度、细胞壁成分的相关QTL和候选基因。研究表明,基于单倍型的QTL定位方法比基于单个SNP的定位效果好。一致性QTL分析将不同遗传群体的研究整合到一起,能够提高QTL结果的通用性。茎秆强度的遗传基础复杂,受微效多基因控制,位点间具有加性效应。茎秆成分QTL中的候选基因涉及细胞壁代谢、转录因子、蛋白激酶等。MAIZEWALL是玉米细胞壁相关基因的重要数据库。目前该数据库包含1 156个玉米细胞壁生物学相关的候选基因,为该领域的深入研究提供强大的资源。已鉴定到一系列影响玉米茎秆细胞壁成分、茎秆形态和强度的基因,其功能涉及纤维素合成路径,如纤维素合成酶类、Cobra类、糖基转移酶和核糖转运蛋白类;苯丙烷路径基因,如控制bm1—bm5的相关基因;植物激素类,如赤霉素、生长素、油菜素甾醇相关基因;转录因子如NAC、MYB;miRNA（ZmmiR528）以及F-box基因（stiff1）等。今后应积极探索不同发育时期玉米茎秆倒伏的力学机制;广泛发展自然群体或育种群体进行遗传分析;采取多种定位策略,提高抗倒伏相关基因鉴定的功效;针对优良等位基因,开发各类分子标记,加强抗倒伏分子标记辅助选择。本文将为玉米茎秆抗倒伏遗传机制解析及抗倒伏玉米品种的分子育种提供参考。     

农业社会化服务体系框架构建与机制研究

农业社会化服务体系是一个多层次、全方位的复杂系统。基于对相关文献的梳理和对我国服务体系发展状况的研究,构建了新时期下农业社会化服务体系运行框架,并对其运行机制进行了分析,提出了新时期下农业社会化服务体系的基本运行机制主要包括监督机制、竞争机制、激励机制、创新机制和利益分配机制。这对我国农业社会化服务体系的完善和顺利发展具有重要的理论意义。     

Practical use of response surface methodology for optimization of veterinary antibiotic removal using UV/H2O2 process

Three of the most commonly used veterinary antibiotics—enrofloxacin (ENR), sulfamethoxazole (SMX), and oxytetracycline (OTC)—were chosen as representative antibiotics for UV/H₂O₂ treatments. The objective was to determine the optimization of UV/H₂O₂ to remove antibiotics from aquaculture discharge water using response surface methodology. The degradation of the antibiotics was investigated under varying UV/H₂O₂ conditions in environments with different levels of pH, water matrices, humic acid, and constituent ions. The degradation results demonstrated that increasing the H₂O₂ dosage facilitated ENR degradation at a neutral pH while facilitating degradation of SMX and OTC at a slightly acidic pH. The optimum removal conditions for ENR, which was used in all influential effect experiments and the contact tank experiments, was obtained at 10 mM H₂O₂, a pretreated COD of 87.51 mg L⁻¹, and an initial pH of 6.15. Among the tested anions, only the presence of Cl^- showed slight positive effects on ENR degradation, due to the generation of secondary active radicals. During the reaction, the hydroxyl radical (OH) was present at a higher pH while singlet oxygen (¹O₂) was slightly present at a lower pH. The experimental results from H₂O₂ sequential addition indicated that freshly added H₂O₂ could quench the recently generated OH and therefore a high H₂O₂ concentration with frequent adding was not necessary. Our contact system reduced the ENR concentration in both the effluent reservoir and in the UV irradiation zone. The overall results supported the use of the UV/H₂O₂ system to treat remnant antibiotics in the discharge water.     

经络穴位给药系统在兽医临床上的应用

经络穴位给药系统以中医经络理论为基础,具有经穴效应和药物效应的双重治疗特性,已广泛应用于兽医临床.目前,兽医临床上常用穴位给药方式是穴位埋植和穴位注射,而常用穴位主要是后海穴、百会穴、肺龠穴.随着经络穴位给药系统的广泛应用,新型经络穴位给药制剂和经络穴位给药作用机理已成为经络穴位给药系统研究的重点.     

分娩应激对围产期奶牛免疫机能的影响

本文分析了围产期奶牛的分娩应激对其免疫机能的影响,并从宏观和微观上进行了详细的阐述,为围产期奶牛的饲养管理提供了理论依据。     

Estimation of litchi (Litchi chinensis Sonn.) leaf nitrogen content at different growth stages using canopy reflectance spectra

The estimation of crop nitrogen status in fresh vegetation leaf using field spectroscopy is challenging due to the weak responses on leaf/canopy reflectance and the overlapping with the absorption features of other compounds. Although the spectral indices were proposed in the literature to predict leaf nitrogen content (LNC), the performance of selected spectral indices to estimate the LNC is often inconsistent. Moreover, the models for nitrogen content estimation changed with the growth stage. The goal of this study was to evaluate the performance of published indices, ratio of data difference index (RDDI) and ratio of data index (RDI) developed by band iterative-optimization algorithm in LNC estimation. The correlation analysis, linear regression and cross validation were used to analyze the relationship between spectral data and LNC and construct the best performed estimation model. The study was conducted by the data of five growing seasons of litchi from the orchards in Guangdong Province of China. Results showed that the relationship between chlorophyll (Chl) related spectral indices and LNC varied with the growth stage. Even in flower bud morphological differentiation stage and autumn shoot maturation stage, there were not significant correlations between the proposed spectral indices and LNC. Besides it is difficult to estimate the LNC by the general model across the growth stages due to the integrated effects of cultivar, biochemical, canopy structure, etc. The band iterative-optimization algorithm can improve the sensitivity of spectral data to LNC to some extent. The optimal RDDI performed better than other indices for the synthetic dataset and the dataset in each growth stage. And the sensitive bands selected in the optimal indices at each growth stage are not consistent, which are not only related to the Chl absorption but also other biochemical components, such as starch, lignin, cellulose, protein, etc. In general, the LNC can be estimated by the optimized CR-based RDDI indices in autumn shoot maturation stage, flower spike stage, fruit maturation stage, and flowering stage with the R² > 0.50 and RMSE < 0.14. Although there were the significant relationship between RDIs and RDDIs in flower bud morphological differentiation stage, the highest R²s of the model developed by RDDIs and RDIs were less than 0.50 in cross validation. This study indicated that the applicability of canopy reflectance to estimate litchi LNC was closely related to the growth stage of litchi. Growth stage-specific models will be preferred for estimating litchi LNC estimation.