培养创新能力的学科竞赛体系构建     

李晖  吴学文  袁莹  朱晓铃 《测绘科学》2017,42(2)

空间信息与数字技术是一门创新性、实践性都很强的专业,涵盖了地理、测绘和计算机等的相关知识;学科竞赛有常规教学不可及的创新教育功能,对培养学生创新实践能力有举足轻重的作用。针对近年来学科竞赛中显现的问题,该文以厦门理工学院空间信息与数字技术专业为例,提出了以创新能力培养为导向的多层次学科竞赛保障体系。结合培养方案和专业建设,面向不同学习阶段学生的知识结构,具体给出了不同参赛层次。将学科竞赛贯穿大学教育始终,反馈并丰富实践教学,切实培养大学生的创新精神和实践能力。  相似文献   

Absence of interactions between perennial bunchgrasses in a semi-arid temperate savanna: a 5-year field experiment     

Guy R McPherson 《Journal of Arid Environments》1997,36(4):565-570

There is widespread recognition of the importance of long-term experimental studies of plant interactions, but such experiments are rarely conducted. Pairwise interactions between three species of perennial grasses were assessed and described over a 5-year period. Experimental treatments in which some or all neighbors were removed were maintained and plant basal area was monitored throughout the experiment. In addition, above-ground biomass was collected over a 3-year period. Repeated-measures analysis of variance revealed no evidence of interactions between plants.  相似文献   

中国的地区企业进入与退出关联研究   总被引：2，自引：1，他引：1  

李蕴雄  任永欢  贺灿飞 《地理科学进展》2016,35(3):349-357

企业的进入退出存在显著的前后关联,关联机制可以分解为竞争效应与乘数效应。本文探讨了1998-2013年间中国制造业企业的空间格局演化过程,发现地级市尺度的企业动态存在明显的时空关联。16年间,企业动态空间格局发生了剧烈演变,逐渐表现出同类型地区集聚现象。利用差分GMM的动态面板模型验证了企业动态在时间上的前后依赖关系。前期的进入与退出对本期企业动态有不同的影响,竞争效应决定企业的进入,乘数效应决定企业的退出。前期企业动态对后期进入的影响会立即显现出来并随时间衰减,而对退出的影响则存在明显滞后效应,在两年之后达到峰值。同时,产业动态关联机制存在显著的空间差异,其中东部地区显示出更强的竞争效应。不同发展水平的地区应采取差别化的政策来指导地区的产业发展,实现产业更新、结构升级和区域经济的可持续发展。东部地区应建立企业准入门槛,降低低效企业退出壁垒;西部地区应该积极吸引新企业进入,并保护在位企业,防止企业退出导致的连锁性萧条。  相似文献   

Predator-Prey Interaction between two Competing Sea Star Species of the Genus Astropecten     

Paul H.  Schmid Rolf  Schaerer 《Marine Ecology》1981,2(3):207-214

Abstract. The predator-prey interaction between two sea star species of the genus Astropecten known to be competitors was investigated at Costa Colostrai, Sardinia, Italy by means of SCUBA-Diving. It was estimated that predation of A. aranciacus would eliminate about 1 % of the prey population of A. bispinosus daily. Because densities of A. bispinosus were observed to be unaltered during the summer months, a considerable immigration of A. bispinosus into the area has to be postulated. A. bispinosus represents 40% of the dry organic matter consumed by A. aranciacus , and is one of the most important food items of this species.
A. aranciacus is not more efficient in preying upon A. bispinosus than in preying upon other food items; but efficiency is greater upon buried sea stars than upon walking ones.
Consequences for stability of the local ecosystem are discussed.  相似文献   

Habitat Selection and Space Partitioning among two Mediterranean Blenniid Species   总被引：4，自引：0，他引：4  

Veronika H.  Koppel 《Marine Ecology》1988,9(4):329-346

Abstract. The utilization of the spatial resources of two syntopic blenniid species - Blennius cunevue and Blennius incognitas - has been investigated in silu and under laboratory conditions. Both species occupy bore holes of the mussel Lithophugu in the sublittoral zone. B. cunevue dominates the more shallow zone (= 0.68 m) and prefers smaller (= 12.76 mm diameter) and horizontal bore holes. B. incognitus inhabits the same depth range as B. cunevue but occupies larger bore holes (= 14.57 mm) in a deeper zone (= 0.86 m). Individuals of B. incognitus do not prefer a special inclination angle. The two blenniid species defend territories with different intraspecific sizes: the mean territory radius of B. cunevue is 6.87 mm, of B. incognitus = 10.95. Mechanisms to reduce competition include different activity rhythm, interspecific social dominance, and differences in territoriality. B. cunevue is the dominant species; its territories arc defended against conspecifics and against B. incognitus.  相似文献   

Polymorphic Zooids in Deitaic Species Populations of Conopeum seurati (CANU, 1928) (Bryozoa, Cheilostomata)     

Angelo  Poluzzi Bruno  Sabelli 《Marine Ecology》1985,6(3):265-284

Abstract. Deltaic populations of Conopeum seurati from diverse environmental settings have variable phenotypes related to strong competitive regimes and to dissolved oxygen minima. Under extremely stressful conditions, the poorly canalized phenotype of C. seurati displays new additional features such as kleistozooids ( kleistós = closed) and chaotic celleporoid layers. Kleistozooids are clearly distinguishable polymorphs characterized by the presence of a compact, imperforate frontal membrane and by a strongly reduced lumen of the "opesium". They commonly aggregate in clusters of regularly-arranged individuals that store a large quantity of proteic material. The inferred function of these cell-like structures is to supply nutrients for basic colony activities. Celleporoid layers are, possibly, a developmental relaxation of the colony of C. seurati for a more efficient use of space in competitive interactions.
Both celleporoid layers and kleistozooids reveal the magnitude of intracolony variability of a widespread opportunistic bryozoan species.  相似文献   

Resource Competition and Selective Grazing of Plankton in a Multispecies Pelagic Food Web Model*     

Roel Riegman  Bouwe R. Kuipers 《Marine Ecology》1994,15(2):153-164

Abstract. An idealized mathematical, multispecies model of the pelagic foodweb was used to explore the impact of resource competition, selective grazing, and species composition within each trophic level on the structure and functioning of a foodweb at a variety of light irradiance and nutrient levels. This concept is based on the general assumption that poorly edible species are poor competitors. The concept demonstrates that with increasing eutrophication, specialists in competition will be replaced by generalists and subsequently by poorly edible primary producers. Controlling factors not only determine the growth rate of primary producers but also select predators according to their ability to utilize the energy fixation of the system. Plankton community structure seems to adapt in such a way that the energy fixation rate of the system is optimized at a given set of nutrients and light. Red tides, dense algal blooms in shallow lakes and the varying results of biomanipulation in shallow lakes, can be explained by the concept of selective grazing. If this assumption is correct, the same ecosystem concept may be applicable for terrestrial ecosystems.  相似文献   

Cultured Atlantic salmon in nature: a review of their ecology and interaction with wild fish   总被引：4，自引：0，他引：4  

Jonsson  Bror; Jonsson  Nina 《ICES Journal of Marine Science》2006,63(7):1162-1181

  相似文献   

Complementary (secondary) metabolites in a soft coral: sex-specific variability, inter-clonal variability, and competition   总被引：2，自引：0，他引：2  

Beatriz Fleury  John Coll  & Paul Sammarco 《Marine Ecology》2006,27(3):204-218

Sex‐specific interactions involving competition for space between the dioecious alcyonacean soft coral Sarcophyton glaucum and the scleractinian coral Acropora robusta were assessed experimentally on Bald Rock, central region of the Great Barrier Reef. To examine this, plus inter‐clonal responses, one male colony of S. glaucum, known to produce sarcophytoxide as its predominant complementary (secondary) metabolite, was sectioned, producing 10 clones. The same was done for a female colony. These two sets of clones were then relocated to grids and placed in contact with Acropora clones. Relocated and non‐relocated controls were also monitored. High levels of tissue necrosis were observed in the hard coral under contact conditions with both the male and female clones after 20 days. The development of a protective polysaccharide layer in the alcyonacean was also observed. Differences observed in the concentrations of complementary metabolites within the two different S. glaucum colonies were related to sex. Both under competition and non‐competition conditions, females exhibited significantly higher concentrations of sarcophytoxide than males, and this increased with time. Fatty ester concentration was also higher in females than males, varying significantly through time, and falling dramatically just after spawning. Fatty ester concentrations decreased linearly through time in the male clones. When involved in competition for space, females possessed higher concentrations of fatty esters than males, both at the site of contact and in non‐contact sites, again, decreasing after spawning. No significant changes in sarcophytoxide levels were noted in the parental colonies, but such changes were observed in fatty esters, with the female producing higher concentrations until after spawning. The use of these two variates in the form of a ratio (sarcophytoxide concentration:fatty ester concentration) yielded a variable Rho (ρ) which was a more sensitive indicator of biochemical change than either of its components alone. These two sets of compounds appeared to have a negative association through time and varied highly significantly between sexes. The diterpene sarcophytoxide may be considered an allelopathic or stress metabolite, while the lipids act as energy storage metabolites.  相似文献   

不同起始浓度对塔玛亚历山大藻和赤潮异弯藻种群竞争的影响   总被引：16，自引：0，他引：16  

董云伟  董双林  刘相义 《中国海洋大学学报(自然科学版)》2004,34(6):964-968

初步分析了起始浓度对塔玛亚历山大藻 (AlexandriumtamarenseBalech)和赤潮异弯藻 (HeterosigmaakashiwoHa da)种群增长的影响。在单种培养的情况下 ,A .tamarense与H .akashiwo的生长曲线可用逻辑斯谛增长模型拟合。不同起始浓度 ( 0 .2× 10 4,0 .5× 10 4,0 .8× 10 4cell/mL)对A .tamarense环境容纳量 (K)有明显的影响 ,随起始浓度的增加K有减小的趋势。H .akashiwo种群瞬时增长率 (r)随起始浓度增加而增加。按不同接种比例进行混合培养 ,不同起始浓度对 2种藻竞争的结果具有明显影响。当接种比例为A .tamarense∶H .akashiwo(A∶H) =1∶4时 ,H .akashiwo在竞争中占优势 ,而当A∶H =1∶1及A∶H =4∶1时 ,A .tamarense在竞争中占优势。竞争结果不仅受营养盐限制 ,克生物质对竞争结果亦具有重要影响。  相似文献