繁昌县城市森林建设浅析

指出了由城镇化的发展带来的环境压力,使得建设城市森林势在必行,进而分析了城市森林的碳汇功能和低碳排放,以城市森林的内涵指出其建设中实现三个转变:从注重视觉效果向视觉与生态功能兼顾的转变;从注重绿化建设用地面积的增加向提高土地空间利用效率的转变;从集中在建成区的内部绿化美化向建立城乡一体的城市森林生态系统的转变,由此及彼探讨了繁昌县城市森林建设存在的优劣势,既往遗留的问题,梳理了原因。最后提出了全面建设森林县城必须要采取的应对措施。     

Development of site index curves for Pinus kesiya in the Philippines

This study was conducted to develop a height–age growth model and site index curves for site quality evaluation of old secondary-growth stands of Pinus kesiya in the northern Philippines. The Chapman-Richards growth function was used in the guide curve method to generate anamorphic site index curves for this species. In order to evaluate the developed model, coefficient of determination (R ² ), root mean square error (RMSE), bias (ē), absolute mean difference (AMD) and mean percent bias (MPB) were used as statistical criteria. The Chapman-Richards model explained about 96.84% of the total variation of the dominant height. The value of ē was ?0.004 m, AMD was 2.566 m, MPB was 3.88% and RMSE was 3.331. The site index curves developed as a result of this study are significant for forest managers in predicting the growth patterns and classification of site productivities for Pinus kesiya stands.     

乳酸菌的生理功能及其在食品工业中的应用

乳酸菌赋予发酵食品较佳的营养价值和保健功能,因此在发酵食品工业中的应用较为广泛。对乳酸菌的生理功能及其在食品工业中的应用进行综述,为乳酸菌发酵食品的研究和开发提供一定的理论依据,并对乳酸菌在食品工业中的应用前景进行展望。     

Current experimental models,assessment and dietary modulations of intestinal permeability in broiler chickens

Maintaining and optimising the intestinal barrier (IB) function in poultry has important implications for the health and performance of the birds. As a key aspect of the IB, intestinal permeability (IP) is mainly controlled by complex junctional proteins called tight junction proteins (TJ) that link enterocytes together. The disruption of TJ is associated with increased gut leakage with possible subsequent implications for bacterial translocation, intestinal inflammation, compromised health and performance of the birds. Despite considerable data being available for other species, research on IP in broiler chickens and in general avian species is still an understudied topic. This paper reviews the available literature with a specific focus on IP in broiler chickens with consideration given to practical factors affecting the IP, current assessment methods, markers and nutritional modulation of IP. Several experimental models to induce gut leakage are discussed including pathogens, rye-based diets, feed deprivation and stress-inducing agents such as exogenous glucocorticoids and heat stress. Although various markers including fluorescein isothiocyanate dextran, expression of TJ and bacterial translocation have been widely utilized to study IP, recent studies have identified a number of excreta biomarkers to evaluate intestinal integrity, in particular non-invasive IP. Although the research on various nutrients and feed additives to potentially modulate IP is still at an early stage, the most promising outcomes are anticipated for probiotics, prebiotics, amino acids and those feed ingredients, nutrients and additives with anti-inflammatory properties. Considerable research gaps are identified for the mechanistic mode of action of various nutrients to influence IP under different experimental models. The modulation of IP through various strategies (i.e. nutritional manipulation of diet) may be regarded as a new frontier for disease prevention and improving the health and performance of poultry particularly in an antibiotic-free production system.     

基于“3414”的三七氮磷钾施肥量研究

通过研究氮磷钾肥对三七[Panax notoginseng（Burk）F.H.Chen]产量及主要有效成分产量的影响,为三七种植生产推荐合理的施肥量,试验采用"3414"随机区组设计,进行连续2年的田间小区试验,测定三七植株农艺性状、产量、总皂苷产量等指标,通过肥料效应函数方程拟合氮磷钾施肥量。结果表明,施肥不同程度促进了三七株高、茎粗、叶长、叶宽等农艺性状,且以适当施氮和磷的效果为最佳;二年七（二年生三七）对钾的依赖性较氮磷强,而三年七（三年生三七）对氮的依赖性最强;施氮能显著提高三七单位面积总皂苷产量,在低氮水平即可获得最高总皂苷产量,而磷、钾肥对皂苷含量及总皂苷产量的影响不明显;氮磷钾对三七产量的影响有互作效应,低磷、中钾水平利于氮肥肥效发挥,低氮、中钾水平利于磷肥肥效发挥,而低氮、中磷水平利于钾肥肥效发挥。根据三七总皂苷产量的三元二次回归方程,最大化三七总皂苷产量的施肥量：二年七为N 157~164 kg·hm^-2、P₂O₅ 179~187 kg·hm^-2、K₂O 337~356 kg·hm^-2;三年七为N 192~200 kg·hm^-2,P₂O₅ 179~187 kg·hm^-2,K₂O 412~435 kg·hm^-2。因此,分别针对二年七和三年七,适当控制施氮量和施钾量,增加施磷量,将三者进行合理配比,对提高单位面积三七总皂苷产量有重要意义。     

CRISPR/Cas9技术发展及其应用进展

概括了CRISPR/Cas9系统的结构及作用原理,分析了该系统的不足,重点阐述了该技术在林木基因组编辑中的应用,并对CRISPR/Cas9系统的未来研究趋势进行了展望。     

中长期径流预报模型优选研究

【目的】对中长期径流预报模型进行比较和优选,为中长期径流预报模型的应用及提高预报精度提供参考。【方法】以黄河流域黑石关、龙门、民和水文站年径流为研究对象,利用灰色预测进行趋势分析、逐步回归进行周期分析,两者耦合建立灰色-逐步回归周期模型;利用逐步回归分析确定均生函数的周期性基函数,耦合建立均生函数-逐步回归模型;利用灰色-逐步回归中的趋势项和周期项作为预报因子,建立投影寻踪回归模型;利用前4年的实测径流数据预报当年径流,建立BP神经网络模型,并通过信息熵原理进行站点模型的综合评价和优选。【结果】建模期除黑石关水文站BP神经网络模型外,各站点拟合预报的平均相对误差均小于11.0%,合格率均大于90%。验证期除民和水文站灰色-逐步回归周期模型外,各站点平均相对误差均小于20%,合格率等于或大于80%,满足精度要求。【结论】均生函数-逐步回归径流预报模型可作为黑石关水文站的优选模型,BP神经网络径流预报模型可作为龙门和民和水文站的优选模型。     

借贷牧户偿债能力分析

【目的】国家对牧区金融发展的支持,以及牧户对资金周转的需求使得牧区贷款较为普遍。贷款 意味着牧户需要有还本付息的能力,因此,评价牧户的偿债能力,能为国家改善牧区发展提供一定的依据。【方法】 运用文献综述法和描述性统计法对当前牧户借贷情况以及锡林郭勒盟整体的生产生活情况进行理论和现状分析。 基于实地调研数据,通过演绎推理牧户的现金流和收益函数来评价牧户的偿债能力。【结果】牧区的还本能力 较低,其付息能力相对较高。现金流入与流出的不对等,降低了牧户的偿债能力。2015—2017 年实际牲畜出栏 数量均小于收支均衡时的出栏量,牧户产生的利润为零,牧户处于亏损状态,牧户的偿债能力比较弱。【结论】 对养畜规模或出栏规模较大的牧户可以适度增加借贷额度,反之,应减少借贷额度;金融机构放贷期限应该灵 活变动;建议政府对牧户有外部的资金支持,适时补贴,缓解牧户的借贷压力,增强其偿债能力。     

中草药复方制剂对青脚麻鸡法氏囊免疫功能、抗氧化性及增殖凋亡基因表达的影响

试验旨在研究由金银花、黄连、蒲公英等药材组成的中草药复方制剂,对青脚麻鸡法氏囊组织结构、抗氧化功能、细胞因子和抗体分泌及增殖凋亡相关基因(PCNA和Caspase-3)表达的影响。采用单因子试验设计,将400羽青脚麻鸡按照体重相近原则分为对照组(基础日粮)和试验Ⅰ-Ⅲ组(分别添加0.5%、1.0%和1.5%中草药复方制剂),每组5个重复(n=20),试验期56 d。结果表明,28日龄时,添加1.0%中草药复方制剂可增加青脚麻鸡法氏囊细胞因子(IL-2和IFN-γ)、IBDV抗体和GSH-Px含量及PCNA mRNA和蛋白表达量(P0.05),降低Caspase-3 mRNA和蛋白表达量(P0.05)。56日龄时,添加1.0%中草药复方制剂可增加青脚麻鸡法氏囊IFN-γ、IBDV抗体和GSH-Px含量(P0.05),降低MDA含量及Caspase-3蛋白表达量(P0.05)。显微观察可见,28和56日龄时,添加1.0%中草药复方制剂可显著增加法氏囊小叶和淋巴小结面积(P0.05),降低法氏囊Caspas-3阳性细胞数量,说明日粮中添加1.0%中草药复方制剂对法氏囊组织结构及免疫抗氧化功能均有明显改善,对法氏囊增殖和凋亡相关基因表达有明显调控作用。文章分别从分子和组织水平揭示中草药复方制剂对青脚麻鸡法氏囊生长发育和免疫功能的影响及可能机制,为新型中草药复方制剂研发及其在青脚麻鸡生产中的应用提供科学依据。