图书采购招标的实践与思考——浙江同济科技职业学院图书采购招标体验

随着《中华人民共和国政府采购法》正式颁布实施,采购管理的不断规范化,图书采购招标势在必行。本文全面介绍浙江同济科技职业学院图书馆实行采购招标过程、招标结果等情况。分析了采购招标实践成功原因,总结招标过程中应注意问题,并提出相应对策。     

东北农业大学图书馆图书采购资金分配问题初探

通过利用层次分析法对东北农业大学图书馆图书采购资金分配到各类图书建立模型并进行分析,从而判断现有馆藏是否合理,为今后的资金分配走向开辟新思路。     

中国农产品补贴的经济效应及政策调整

用经济学的方法,对开放型的贸易小国两种农产品补贴产生的经济效应和对生产者行为影响进行介绍,并同中国多数农产品补贴效应进行比较．然后简单描述了中国农产品的生产和贸易情况,在此基础上分析了中国大多数农产品两种补贴对双重角色下的农民和一般消费者产生的经济效应及生产者行为偏好的变化,得出简短的结论和建议。     

用户信息需求在线调查与研究

根据用户对馆藏信息资源需求的调查、分析,结合现有馆藏信息资源和上一年度文献信息的入藏情况做进一步的阐述。     

中国南方地区植保无人机补贴体系的政策效应及优化策略

为探讨政府补贴对中国南方地区中小农田、丘陵山区无人机植保普及率的政策效应,选择小块农田与坡地,通过3种主流无人机型的植保服务作业试验,分析政府补贴对作业成本、专业服务团队收益等因素的影响。结果表明:政府补贴对无人机植保普及率的提升有明显的促进效应,购置补贴对降低无人机植保作业成本的作用有限,但作业补贴能够显著促进专业服务团队更好地为中小农田、丘陵山区服务。本研究进一步提出补贴体系的优化策略:购置补贴需要增加新的标准,作业补贴需要分类细化为基础作业补贴、飞防药剂补贴、丘陵山区作业补贴、偏远地区运输补贴、特种作物作业补贴5种类型。     

临时收储政策退出对玉米期货和现货价格发现功能的影响

借助改进的蛛网模型,分析了临时收储政策退出对我国玉米期货和现货市场价格发现功能的影响机理;并综合运用滚动协整、VECM、BEKK-GARCH与IS模型,系统探究了2009-2019年我国临储政策及其改革对玉米期货和现货市场价格发现功能的影响.研究发现:1)我国玉米期货和现货价格存在相互引导关系.2)BEKK-GARCH...     

基于电子商务O2O模式的利弊研究——以糯米网为例

随着电子商务行业的迅猛发展,国内渐渐形成了一种电子商务新模式,即:O2O模式。O2O模式的兴起,冲击着当今经济格局,越来越发展为不可小觑的一股力量。本文以糯米网为研究对象,通过对糯米网与O2O模式融合的研究,找出糯米网在发展过程中的不足,并提出对策。通过对糯米网的完善,找出020模式发展过程中存在的问题,促进O2O模式的完善。     

实施森林分类经营几个问题的探讨

实施森林分类经营是推进林业五个历史性转变的基础。2001年江西省按照国家林业局的有关规定要求，完成了全省森林分类经营区划(规划)工作。本文就实施分类经营中对公益林生态补偿金的标准、分美经营管理模式、生态环境建设目标责任制等问题提出了初步意见。     

Impaired littoral energy pathways cause a shift to pelagic resources by fish in recovering lake food webs

Fish communities may increase in biomass and productivity due to energy subsidies from the littoral invertebrate community. In lakes recovering from acidification and metal contamination, such as those in Sudbury, Ontario, Canada, impaired benthic invertebrate communities (i.e., low diversity with higher abundance of small‐bodied taxa) allowed a critical test of the role of these littoral pathways on fish diet. We compared fish abundance, diversity, diet and biomass in eight recovering and eight reference lakes and related availability of the main littoral and pelagic invertebrate groups to fish diet regime using stable isotope analysis. A Bayesian mixing model (MixSIR) was used to estimate diet likelihood, and convex hull analysis was used to estimate trophic niche space of fish communities. Fish biomass did not differ between impaired and reference lakes despite substantial differences in potential diet. Fish depended strongly on littoral benthos in the reference lakes but consumed more pelagic food in the impaired lakes. The trophic niche of the focal, most common fish species (i.e., yellow perch, smallmouth bass, pumpkinseed and brown bullhead) was larger in the impaired lakes. We attributed these differences to low diversity at the highest trophic levels of fish communities in the impaired lakes as well as to depauperate benthic invertebrate communities. In contrast to the food webs of most temperate lakes, fish in impaired lakes preyed less on littoral invertebrates yet still managed to maintain a reference lake level of biomass standing crop by relying more on pelagic resources – macro zooplankton such as Chaoborus.     

Non‐native rainbow trout (Oncorhynchus mykiss) occupy a different trophic niche to native Breede River redfin (Pseudobarbus burchelli) which they replace in South African headwater streams

Recent research has revealed that non‐native rainbow trout Oncorhynchus mykiss have largely replaced a native cyprinid, the Breede River redfin Pseudobarbus burchelli, as the dominant species of fish in many headwater streams in the Cape Floristic Region (CFR) of South Africa. Moreover, differences in the composition of benthic communities in CFR headwater streams with and without trout suggest that trout do not functionally compensate for the native redfin which they have replaced in these food webs. In this study, we used gut content and stable isotope analyses to characterise and compare the trophic niches and diet compositions of allopatric populations of trout and redfin in six CFR headwater streams (three containing trout, three containing redfin). Results indicate that native redfin exploit a broader trophic niche, and a more omnivorous diet, than do trout. Gut content analyses showed terrestrial invertebrates to be an important prey source for trout, which could potentially offset predation pressure on aquatic invertebrates and explain why benthic invertebrate density in streams with trout is higher than that in streams with no trout. Contrastingly, redfin diet appeared to be dominated by aquatic invertebrates, with terrestrial prey a less important food item in the guts of redfin. That redfin and trout exploit nonequivalent trophic niches may have consequences for benthic community composition in CFR headwater streams, and this study highlights the importance of quantifying how the functional role of predators changes following a predator replacement for understanding and managing the consequences of non‐native predator invasions.