嗜线虫致病杆菌抗菌代谢产物Xcn1的研究进展

Xenocoumacin1（Xcn1）是嗜线虫致病杆菌产生的一种水溶性小肽类抗菌化合物，对真菌和细菌具有广谱的抑菌活性，在农业病害防治中具有良好的开发和应用前景。本文综述了Xcn1化合物的合成和降解机制、合成调控机制、抗菌作用机制以及防控植物疫病的研究进展，并展望了高产Xcn1生产菌株的改良和产业化应用前景。     

中国林产工业集聚水平测度及演进趋势与产业经济增长——基于2003—2016年数据的实证分析

利用产业集聚指数和产业区域集中度测算2003—2016年中国林产工业两位数产业集聚水平，并实证分析林产工业两位数产业集聚与其经济增长的关系。研究表明:1）木材加工业和家具制造业处于中度集聚状态，而造纸与纸制品制造业处于低度集聚状态；2）木材加工业集聚度呈上升趋势，而家具制造业和造纸与纸制品制造业集聚度呈下降趋势；3）中国林产工业主要集聚在经济发达的江苏、广东、山东和浙江等沿海省份，但木材加工业和家具制造业分别在广西和四川有较快增长趋势；4）木材加工业集聚水平与其产业经济增长呈正相关，而家具制造业和造纸与纸制品制造业集聚与其产业经济增长呈负相关。     

Orange peel fragment improves antioxidant capacity and haematological profile of Nile tilapia subjected to heat/dissolved oxygen‐induced stress

This study evaluated the ability of orange peel fragment (OPF) to act as a functional feedstuff, influencing growth, haematological profile, and antioxidant enzyme activity of Nile tilapia subjected heat/dissolved oxygen‐induced stress (HDOIS). A group of 440 male Nile tilapia (31.7 g ± 0.34) was randomly distributed in 40 250‐L aquaria (11 fish/tank) and fed five practical diets with graded levels of OPF at 0%, 0.2%, 0.4%, 0.6%, and 0.8% for 70 days. The diets were formulated to contain 30% crude protein and 18 MJ/kg crude energy. After the feeding period, growth performance was evaluated and six fish per treatment were sampled for haematological profile and antioxidant enzyme activity, before and after HDOIS. Then, fish were subjected to HDOIS (32°C/2.3 mg/L dissolved oxygen) for three days and the same haematological profile and antioxidant enzyme activity were determined. There was no effect of OPF on the haematological profile, either before or after HDOIS. The polynomial regression model was used to express the relationship between antioxidant enzymes activity and OPF supplementation level. The maximum activity of superoxide dismutase, catalase, and glutathione peroxidase was reached at 0.66%, 0.63%, and 0.68% of OPF respectively. Results of the present study suggest that a dietary supplementation level of 0.63%–0.68% of orange peel fragment was appropriate to maintain Nile tilapia haematological profile and improve its antioxidant capacity under HDOIS.     

Assessment of short-term mortality of granary weevil,Sitophilus granarius (Coleoptera: Curculionidae) triggered by different microwave irradiation powers

Abstract

The insecticidal efficacy of microwave irradiation against the at 12, 24, 48 and 72?h following exposure to microwave irradiations (100, 300?W) and the progeny production was assessed 45?days later. Linearly increasing irradiation power range (100, 200 and 300?W) was set up for determining mortality tendency. An increase of insect mortality caused by higher irradiation period and times elapsed after treatment has become evident commencing from 12?h after the treatment, which has significantly decreased at later elapsed time after treatment. The irradiation periods inducing the highest mortality at the examined powers were at 10?min and at 100?W power (72?h: 64.93%) and at 4.5?min. and at 300?W power (12?h: 87.01). In addition, a complete suppression of progeny production was achieved by 4.5?min treatment at 300?W power. Lognormal-type mortality process was caused by the linearly increased irradiation range. The properly chosen microwave irradiation can be used for management of Sitophilus granarius larval and adult developmental stages. This treatment could provide an effective and friendly environmental treatment technique in Integrated Pest Management (IPM) program.     

基于体验经济的乡村花卉旅游产品提升策略研究

旅游从诞生之初就具备了体验经济的属性，而创造独特的、难忘的、新奇的旅游体验，让旅游 者在旅行过程中获得多层次需求的满足成为旅游企业努力的方向。在体验经济时代背景下，针对乡 村花卉旅游市场，了解游客市场需求，发挥资源优势，转变运营思路，对原有的花卉旅游产品进行提升 和创新是目前值得思考研究的课题。根据模型提出乡村花卉旅游产品的提升策略，主要是针对存在 的问题提出相应的解决方案，结合理论给出系统的产品建议，同时也提出了政府、企业、乡村、人才培 养等方面保障建议以促进花卉旅游的可持续发展。     

乳业产业系统发展状态测度研究——基于协同论的实证分析

科学测度乳业产业系统发展状态,是提升乳业竞争力和实现乳业可持续发展的内在要求。乳业产业系统具有复杂性和内部交互性,可划分为原料乳供应、乳制品加工、乳制品销售和乳制品消费4个子系统。基于协同理论,采用驰豫系数法,利用2006—2015年中国乳业数据,分析乳业产业系统发展状况和各子系统的有序发展状况,探讨其协调发展水平。结果表明,乳业产业系统协同度最高值仅为0.024,尚未形成良好的发展状态;各子系统有序度水平均处于较低水平,最高值为0.244,其中乳制品加工子系统有序度水平相对较高,但上升缓慢。乳业产业各子系统之间存在着相互作用,乳制品加工与乳制品消费子系统的相互影响最强,而原料乳供应与乳制品销售子系统的相互影响最弱。研究表明,要实现乳业产业系统高效协同发展,需要乳业产业所有子系统的运营状态都提高。因此,提出加强优质奶源基地和优质饲草体系建设;继续实行乳企兼并重组战略、丰富产品结构以深入开发国内外市场、加强乳企品牌建设;加强行业发展成就展示和消费引导等促进乳业可持续发展的政策建议。     

Effects of length of ensiling and maturity group on chemical composition and in vitro ruminal degradability of whole‐crop maize

Nine hybrids (three maturity groups, dry matter 343 ± 5.6 g/kg) of whole‐crop maize were ensiled in eight replicates in laboratory‐scale silos. Each hybrid was sampled at harvest and after 30, 60, 90 and 120 days (d) of ensiling. Samples were analysed for chemical composition (proximate constituents, fermentation products and pH), starch, non‐protein N (NPN) and NH₃‐N. Each sample and its neutral detergent fibre (NDF) fraction were incubated in the Hohenheim gas test system. In vitro gas production was measured after 0, 2, 4, 8, 12, 16, 24, 36, 48, 72 and 96 hr of incubation. Gas production of the neutral detergent soluble (NDS) fraction (mainly starch) was calculated using a curve subtraction method. Gas production dynamics over time were estimated using a nonlinear regression equation; afterwards, a two‐factorial analysis of variance (storage length, maturity group and their interaction) using the general linear models procedure was conducted. After 30 d, all silages were well fermented. Most fermentation products and proximate constituents only changed until 30 or maximum 60 d of ensiling. Only few changes in in vitro nutrient degradability were detected after the first 30 d or as influenced by maturity group. Ensiling per se increased the ruminal degradability of the NDS, but there was no further increase caused by a prolonged duration of storage. However, extensive changes in crude protein fractions occurred with a linear increase in NPN and NH₃‐N compounds from 0 to 120 d of storage, indicating continual protein and amino acid degradation.     

基于品牌效应的在线评论对稻米销量影响的实证研究

为探索品牌、在线评论与农产品销量之间的关系以及二者如何对农产品销量产生影响。利用网络爬虫技术和统计方法,基于品牌效应视角,扩展了采纳信息模型,并依据网络中采集的真实在线评论内容,从产品特征和评论特征两个角度出发对稻米农产品进行研究,构建了稻米销量的影响因素模型并运用实际数据分析得到验证。结果表明:评论数量与稻米销量显著相关,品牌强度、评论效价和评论时效度对于稻米销售具有显著的正向影响。此外,评论效价和评论时效度能够削弱品牌强度的作用,对弱势品牌稻米销量具有更为显著的影响。     

中国与亚太地区主要国家木质林产品贸易竞争性与互补性分析

亚太地区拥有丰富的森林资源，中国与亚太地区主要国家林业经贸合作前景十分广阔。文中运用显性比较优势指数、贸易互补性指数和产业内贸易指数分别对2006—2015年中国与亚太主要国家木质林产品贸易的竞争性与互补性进行分析，结果表明:与亚太主要国家相比，中国木质林产品竞争力较弱，但与其贸易互补性很强。中国应积极加快木质林产品结构转型，提升产品质量以增强竞争力，并利用贸易互补性扩大与亚太主要国家的林产品贸易规模，实现区域互利共赢。     

基于格网的石漠化地区生态系统服务与经济空间耦合

[目的]分析石漠化地区生态系统服务价值与经济的空间耦合关系,为石漠化地区生态环境保护与社会经济协调发展提供依据。[方法]以贵州省盘州市为例,基于格网尺度,计算了研究区生态服务价值(ESV)与国内生产总值GDP,并利用耦合协调模型,对两者间的耦合协调发展程度进行定量评估。[结果]①盘州市ESV热点区主要分布在东北部的几个少数民族乡镇,冷点区主要分布在经济发展较快且城市化率较高的区域;②盘州市GDP在空间上呈现出局部高的特点,高值区主要集中在石桥镇、亦资街道、翰林街道等工业镇和政治、经济、文化中心;③盘州市ESV与GDP耦合协调度值较低,空间上存在明显的自相关性,耦合协调度较低的区域主要分布在盘州市东南部、北部以及中部;④盘州市ESV与GDP耦合协调度类型以严重失调衰退经济损益型为主,占区域总面积的79.95%。[结论]盘州市ESV与GDP在空间上存在一定矛盾,耦合协调度较低,兼顾生态环境保护与经济发展有助于提升协调度。