نتایج جستجو برای: trophic evaluation

تعداد نتایج: 839178  

2013
Shawn A. Steffan Yoshito Chikaraishi David R. Horton Naohiko Ohkouchi Merritt E. Singleton Eugene Miliczky David B. Hogg Vincent P. Jones

Food web ecologists have long sought to characterize the trophic niches of animals using stable isotopic analysis. However, distilling trophic position from isotopic composition has been difficult, largely because of the variability associated with trophic discrimination factors (inter-trophic isotopic fractionation and routing). We circumvented much of this variability using compound-specific ...

Journal: :Journal of cell science 1970
H C Macgregor H Stebbings

The telotrophic ovary of Notonecta glauca glauca consists of 7 ovarioles. Each ovanole comprises, from front to rear, a terminal filament, a trophic region, a prefolhcular region, and a series of 10-15 follicles of progressively increasing size The trophic region is largely syncytial and is made up of polyploid trophic nuclei packed around a central trophic core The cytoplasm of the trophic cor...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه فردوسی مشهد - دانشکده ادبیات و علوم انسانی دکتر علی شریعتی 1391

the major aim of this study was to investigate the relationship between social and cultural capital and efl students’ critical thinking skills. this study takes this relationship in to account to see if people with different sociocultural status are different regarding their critical thinking skills. to this end, 160 university students majoring in english language and literature, english trans...

Journal: :Environmental pollution 2013
Stephanie L Wright Richard C Thompson Tamara S Galloway

Plastic debris at the micro-, and potentially also the nano-scale, are widespread in the environment. Microplastics have accumulated in oceans and sediments worldwide in recent years, with maximum concentrations reaching 100 000 particles m(3). Due to their small size, microplastics may be ingested by low trophic fauna, with uncertain consequences for the health of the organism. This review foc...

Journal: :international journal of aquatic biology 0
amir hossein hamidian mansoureh hassanzadeh

eutrophication is known as the most common problem in water bodies, caused by high concentrations of different nutrients leading to unbalanced growth of aquatic plants, among other symptoms. hence, the possibility of eutrophication prediction can be beneficial to the sustainable management of these natural resources and create an opportunity to control their trophic conditions over time. a soft...

2002
Simon Jennings John K. Pinnegar Nicholas V. C. Polunin Karema J. Warr

Models of biomass size spectra assume that organisms with higher body mass feed at higher trophic levels, but explicit empirical tests of this pattern are rare. We used nitrogen stable isotopes (δ15N) as an index of the trophic level in a benthic fish and invertebrate size-spectrum, and demonstrated that body mass was positively and significantly related to trophic level. This pattern was consi...

2014
Yoshito Chikaraishi Shawn A Steffan Nanako O Ogawa Naoto F Ishikawa Yoko Sasaki Masashi Tsuchiya Naohiko Ohkouchi

Food webs are known to have myriad trophic links between resource and consumer species. While herbivores have well-understood trophic tendencies, the difficulties associated with characterizing the trophic positions of higher-order consumers have remained a major problem in food web ecology. To better understand trophic linkages in food webs, analysis of the stable nitrogen isotopic composition...

Journal: :Prague medical report 2008
J Barcal J Cendelín F Vozeh

Possible effect of trophic factors from embryonic cerebellar graft transplanted in adult Lurcher mutant mice on LTP as electrophysiological marker of learning and memory process was studied. Also the combination of the transplantation and long-term forced motor training was investigated. An evaluation of LTP ability in four animal groups (transplanted, sham-operated, with and without forced mot...

Journal: :Proceedings. Biological sciences 2009
K H Andersen J E Beyer P Lundberg

Individual and trophic efficiencies of size-structured communities are derived from mechanistically based principles at the individual level. The derivations are relevant for communities with a size-based trophic structure, i.e. where trophic level is strongly correlated with individual size as in many aquatic systems. The derivations are used to link Lindeman's trophic theory and trophic theor...

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