排序方式: 共有39条查询结果,搜索用时 78 毫秒
1.
Optimising mineral nitrogen (N) use in crop production is inevitable target as mineral fertilisers reflect one of the highest inputs both in terms of economy and energy. The aim of the study was to compare the relationship between the rate of N fertiliser application and different measures of energy parameters exemplary data for spring-wheat in boreal climate condition in Estonia in 2006–2010. The effect of mineral N with rates 0, 40, 80, 120 and 160 kg N ha−1 was studied on the background of composted cow manure and without organic fertilisers. Univalent parameters, energy gain (EG) (energy output − energy input) and energy ratio (ER) (energy output/energy input) were calculated. To aggregate parameters with different units (ER and EG) we proposed two standardisation approaches for combined indices. ER maximisation gave both organic fertilisation background optimum N norms significantly lower than EG (p < 0.05) optimisation. Both the new combined indices gave optimum N norms in between the rate of ER an EG. Composted cow manure background did not affect mineral N optimisation significantly. We suggest optimisation of mineral N according to bi-dimensional parameters as they capture important features of production efficiency and are more objective using as advisory tool for sustainable production systems. 相似文献
2.
以苎麻品种为材料,研究了苎麻RAPD分析过程中的影响因素,包括10×PCRBuffer、模板浓度、Mg2 、dNTP、引物、Taq酶、循环次数、退火温度等,建立了适于苎麻RAPD分析的PCR反应体系:即在25μl反应体系中,引物浓度为0.4uM;模板DNA的用量为60~100ng;Mg2 浓度为1.8mM;dNTP浓度为0.2mM;Taq酶用量为1U。适宜的扩增程序为先94℃变性4min,再94℃变性45s、38℃复性45s、72℃延伸2min共36个循环,最后72℃延伸5min,4℃保存。 相似文献
3.
Zhu Jizhong Xu Guoyu 《保鲜与加工》1991,(1):12-18
Analyses the characteristics of convex network flow programming of the economic power dispatch with security and presents a rapid algorithm. The numerical examples are given to demonstrate the effectiveness of the algorithm. 相似文献
4.
Should I fight or should I flight? How studying insect aggression can help integrated pest management
下载免费PDF全文
![点击此处可从《Pest management science》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Giovanni Benelli 《Pest management science》2015,71(7):885-892
Aggression plays a key role all across the animal kingdom, as it allows the acquisition and/or defence of limited resources (food, mates and territories) in a huge number of species. A large part of our knowledge on aggressive behaviour has been developed on insects of economic importance. How can this knowledge be exploited to enhance integrated pest management? Here, I highlight how knowledge on intraspecific aggression can help IPM both in terms of insect pests (with a focus on the enhancement of the sterile insect technique) and in terms of biological control agents (with a focus on mass‐rearing optimisation). Then, I examine what implications for IPM can be outlined from knowledge about interspecific aggressive behaviour. Besides predator–pest aggressive interactions predicted by classic biological control, I focus on what IPM can learn from (i) interspecific aggression among pest species (with special reference to competitive displacement), (ii) defensive behaviour exhibited by prey against predaceous insects and (iii) conflicts among predaceous arthropods sharing the same trophic niche (with special reference to learning/sensitisation practices and artificial manipulation of chemically mediated interactions). © 2015 Society of Chemical Industry 相似文献
5.
Abstract Techniques for assessing the impact of structural barriers on fish passage and for prioritising restoration actions are reviewed. Current survey methodologies are biased towards specific structures, primarily culverts and economically significant fish. Assessment criteria are often based on swimming capabilities of upstream migrating adult salmonids, while ignoring other life‐stages, non‐salmonid species, downstream migration and behaviour. The development of comprehensive and centrally owned geospatial inventories of barriers is essential. The collection, maintenance and dissemination of pertinent structural and environmental data can be technically, logistically and financially challenging. Standardised procedures are needed to rapidly and cost‐effectively survey large numbers of barriers over wide geographic areas. The prioritisation of barrier repair and removal projects is most often based on simple cost‐benefit analysis, whereby individual barriers are scored based on a set of assessment criteria and then ranked in order of priority. The benefits of using scoring‐and‐ranking systems, however, are unacceptably low because they consider barriers independently, thereby ignoring the cumulative, non‐additive impacts produced by multiple, spatially interconnected structures. Optimisation modelling offers a more robust approach for efficiently prioritising decision making in river restoration planning, allowing decision makers to account for key uncertainties and effectively balance multiple, possibly competing, environmental and socioeconomic goals and constraints. 相似文献
6.
Green extraction was applied to Argentinean shortfin squid (Illex argentinus) viscera, consisting of a wet pressing method including a drying step, mechanic pressing, centrifugation of the resulting slurry, and oil collection. To maximise the oil yield and ω3 fatty acid content and to minimise the oil damage degree, a response surface methodology (RSM) design was developed focused on the drying temperature (45–85 °C) and time (30–90 min). In general, an increase of the drying time and temperature provided an increase in the lipid yield recovery from the viscera. The strongest drying conditions showed a higher recovery than 50% when compared with the traditional chemical method. The docosahexaenoic and eicosapentaenoic acid contents in the extracted oil revealed scarce dependence on drying conditions, showing valuable ranges (149.2–166.5 and 88.7–102.4 g·kg−1 oil, respectively). Furthermore, the values of free fatty acids, peroxides, conjugated dienes, and ω3/ω6 ratio did not show extensive differences by comparing oils obtained from the different drying conditions. Contrary, a polyene index (PI) decrease was detected with increasing drying time and temperature. The RSM analysis indicated that optimised drying time (41.3 min) and temperature (85 °C) conditions would lead to 74.73 g·kg−1 (oil yield), 1.87 (PI), and 6.72 (peroxide value) scores, with a 0.67 desirability value. 相似文献
7.
渗透坡面林地地表径流运动的有效糙率研究 总被引:15,自引:0,他引:15
在流域水文学研究与应用领域中,坡面水流占有十分重要的地位,但如何获取坡面水流的有效糙率是至关重要的一步。本文针对林地地表径流运动的形成过程和运动特点,建立了林地渗透坡面地表径流运动基本方程,通过讨论土壤水分运动和地表径流运动参数,将土壤水分运动简化为一维Smith-Parlange模型,地表径流简化为运动波模型,采用一步Lax-Wendroff有限差分格式进行数值模拟,以最小离差平方和为目标函数,通过叠代计算获取林地地表径流的有效糙率。根据人工模拟降雨地表径流过程实测资料计算了油松林、刺槐林、蒙古栎林3种林分的有效糙率,计算结果表明,22a生刺槐林地的最大,在0.1931~0.2131之间;其次为30a生蒙古栎林地,为0.1701;20a生油松林地为0.1423。从参数寻优的结果来看,m值在2.76~3.090 相似文献
8.
9.
Past,current and future drivers for the development of decision support systems in forest management
The potential for development in decision support for forest management is set by decision theory, available technology and methods. Demands for decision support are emerging from contemporary challenges and problems of forest management which act as stimuli for the science community. Objectives and approaches in forest management as well as technologies have been changing throughout history. Accordingly, the demand for tools to support planning and decision-making has evolved. In this contribution, the authors review the historic development of decision support systems (DSS) for forest management and discuss past, current and future drivers. Based on evidence from scientific literature, case studies in the frame of the Forest Management Decision Support Systems (FORSYS) action, as well as experiences of the authors some hypotheses about the future of DSS are drawn. It is shown that in the past, the drivers evolving from forest management as well as decision support technologies have influenced the way of how models and methods have been applied as well as how DSS architectures have been designed. It is concluded that in the future, the challenges for DSS development will increase, as the complexity of decision-making processes and the related models will compete with the user demands which ask for simplicity. 相似文献
10.
ISSR分子标记是在SSR标记基础上发展起来的一种新技术,ISSR标记成孟德尔式遗传,在多数物种中是显性的,目前已经广泛应用于植物品种鉴定、遗传作图、基因定位、遗传多样性、进化及分子生态学当中。笔者以苎麻自交系品种为材料,研究了苎麻ISSR分析过程中的影响因素,包括10×PCRBuffer、模板浓度、Mg2 、dNTP、引物、Taq酶、循环次数、退火温度等,建立了适于苎麻ISSR分析的PCR反应体系:即在20ul反应体系中,引物浓度为1.0umol/L;模板DNA的用量为60~100ng;Mg2 浓度为2.0mmol/L;dNTP浓度为0.2mmol/L;Taq酶用量为1U。适宜的扩增程序为先94℃变性5min,再94℃变性30sec、56℃复性45sec、72℃延伸90sec共34个循环,最后72℃延伸7min,4℃保存。 相似文献