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排序方式: 共有113条查询结果,搜索用时 31 毫秒
61.
RG Lockie AB Schultz SJ Callaghan CA Jordan TM Luczo MD Jeffriess 《Biology of sport / Institute of Sport》2015,32(1):41-51
There is little research investigating relationships between the Functional Movement Screen (FMS) and athletic performance in female athletes. This study analyzed the relationships between FMS (deep squat; hurdle step [HS]; in-line lunge [ILL]; shoulder mobility; active straight-leg raise [ASLR]; trunk stability push-up; rotary stability) scores, and performance tests (bilateral and unilateral sit-and-reach [flexibility]; 20-m sprint [linear speed]; 505 with turns from each leg; modified T-test with movement to left and right [change-of-direction speed]; bilateral and unilateral vertical and standing broad jumps; lateral jumps [leg power]). Nine healthy female recreational team sport athletes (age = 22.67 ± 5.12 years; height = 1.66 ± 0.05 m; body mass = 64.22 ± 4.44 kilograms) were screened in the FMS and completed the afore-mentioned tests. Percentage between-leg differences in unilateral sit-and-reach, 505 turns and the jumps, and difference between the T-test conditions, were also calculated. Spearman''s correlations (p ≤ 0.05) examined relationships between the FMS and performance tests. Stepwise multiple regressions (p ≤ 0.05) were conducted for the performance tests to determine FMS predictors. Unilateral sit-and-reach positive correlated with the left-leg ASLR (r = 0.704-0.725). However, higher-scoring HS, ILL, and ASLR related to poorer 505 and T-test performance (r = 0.722-0.829). A higher-scored left-leg ASLR related to a poorer unilateral vertical and standing broad jump, which were the only significant relationships for jump performance. Predictive data tended to confirm the correlations. The results suggest limitations in using the FMS to identify movement deficiencies that could negatively impact athletic performance in female team sport athletes. 相似文献
62.
JÖRG MALETZ MICHAEL STEINER OLDRICH FATKA 《Lethaia: An International Journal of Palaeontology and Stratigraphy》2005,38(1):73-85
The presence of distinct fusellar structure is taken as evidence to include a number of fossils from the Middle Cambrian to the Lower Ordovician of North America and Europe with the Pterobranchia. The dome of the pterobranchs and the prosicula of the planktic graptolites are contrasted and evidence is given for the re‐assignment of a number of well known dendroid graptolites to the pterobranchs. A non‐destructive method is described to reveal fusellar development of delicate hemichordate exoskeletons from shales. Rhabdotubus robustus n. sp. from the Czech Republic and ? Cephalodiscus sp. from the Wheeler Shale of North America are described as new Middle Cambrian pterobranchs. 相似文献
63.
ALEXANDER GALLÉ SILKE LAUTNER JAUME FLEXAS MIQUEL RIBAS‐CARBO DAVID HANSON JOHN ROESGEN JÖRG FROMM 《Plant, cell & environment》2013,36(3):542-552
In recent years, the effect of heat‐induced electrical signalling on plant photosynthetic activity has been demonstrated for many plant species. However, the underlying triggers of the resulting transient inhibition of photosynthesis still remain unknown. To further investigate on this phenomenon, we focused in our present study on soybean (Glycine max L.) on the direct effect of signal transmission in the leaf mesophyll on conductance for CO2 diffusion in the mesophyll (gm) and detected a drastic decline in gm following the electrical signal, whereas the photosynthetic electron transport rate (ETR) was only marginally affected. In accordance with the drop in net photosynthesis (AN), energy dispersive X‐ray analysis (EDXA) revealed a shift of K, Mg, O and P on leaf chloroplasts. Control experiments under elevated CO2 conditions proved the transient reduction of AN, ETR, the chloroplast CO2 concentration (Cc) and gm to be independent of the external CO2 regime, whereas the effect of the electrical signal on stomatal conductance for CO2 (gs) turned out much less distinctive. We therefore conclude that the effect of electrical signalling on photosynthesis in soybean is triggered by its immediate effects on gm. 相似文献
64.
JÜRG FUHRER 《Plant, cell & environment》1982,5(4):263-270
Abstract. Seedlings of Phaseolus vulgaris were exposed to solutions containing Cd2+ in the range 0 to 1 molm−3 . Ethylene formation started following 3 h of exposure to 10−2 , 10−1 and 1 mol m−3 Cd2+ , peaked at 18 h and returned to a relatively low rate after 24 h. Cadmium-induced ethylene formation depended on the formation of 1-aminocyclopropane-1-carboxylic acid (ACC). Aminoethoxyvinylglycine (AVG, 0.1 mol m−3 ) inhibited ACC accumulation and ethylene production during exposure to 0.2 mol m−3 Cd2+ .
Activity of soluble and ionically-bound peroxidase increased after 18 h of exposure to Cd2+ concentrations above 10−3 mol m−3 due to an increase in activity of cathodic isoperoxidases. Stimulation of soluble and ionically-bound peroxidase by 0.2 mol m−3 Cd2+ was reduced in the presence of 0.1 mol m−3 AVG.
Accumulation of soluble and insoluble ('ligninlike') phenolics was found in plants exposed to Cd2+ (10−2 mol m−3 or above) in the presence or absence of AVG. Deposition of insoluble (autofluorescing) material occurred in cell walls around vessels and was associated with reduced expansion and water content of leaves. 相似文献
Activity of soluble and ionically-bound peroxidase increased after 18 h of exposure to Cd
Accumulation of soluble and insoluble ('ligninlike') phenolics was found in plants exposed to Cd
65.
Further Evidence for the Relationship between Light-Induced Changes of Plasmalemma Transport and Transthylakoid Proton Uptake 总被引:1,自引:0,他引:1
VANSELOW KLAUS HEINRICH; KOLBOWSKI J?RG; HANSEN ULF-PETER 《Journal of experimental botany》1989,40(2):239-245
The simultaneous measurement of the induction curves of chlorophyllfluorescence, its responses to saturating flashes, light-scatteringat 532 nm, and plasmalemma voltage supports previous findings(Hansen, Kolbowski, and Dau, 1987), that light-induced uptakeof protons into the inner thylakoid space causes the rapid (5to 20 s) light-induced depolarization at the plasmalemma viasubstrate depletion of the electrogenic H+-pump. These conclusionsare based on kinetic studies which enable the separation ofindividual components in complex signals by means of their assignmentto different time-constants. In contrast to the previous investigation,binary noise was used for modulation of the actinic light. Thenew input signal not only increased the reliability of the previousresults obtained by sine-waves, but also led to the detectionof three additional time-constants. One of these is probablyrelated to the action of light on the potassium channel of theplasmalemma. The others are assigned to the quencher Q and toa still unknown process. Key words: Chlorophyll fluorescence, plasmalemma potential, proton fluxes, noise, scattering, spinach, state-transitions, thylakoid membrane 相似文献
66.
J
RG U. GANZHORN 《Ethology : formerly Zeitschrift fur Tierpsychologie》1987,74(2):146-154
Soil consumption of two Malagasy lemurs, Lemur catta and Lemur fulvus was observed in an enclosure simulating a natural habitat at Duke University Primate Center (Durham, USA). Soil eaten by L. catta contained more Na than random soil samples. Concentrations of the four major minerals in soil eaten by L. fulvus did not differ from random samples. L. fulvus stopped soil ingestion in summer when they ate large amounts of foliage rich in K and Mg, also in winters after being fed with MgCl2. It is suggested that, in this study, soil was consumed in relation to its mineral content and not for physical properties related to its structure. Some non physiological factors that might influence food selection are discussed. 相似文献
67.
THORSTEN E. E. GRAMS SILKE LAUTNER HUBERT H. FELLE RAINER MATYSSEK & JÖRG FROMM 《Plant, cell & environment》2009,32(4):319-326
Combining measurements of electric potential and pH with such of chlorophyll fluorescence and leaf gas exchange showed heat stimulation to evoke an electrical signal (propagation speed: 3–5 mm s−1 ) that travelled through the leaf while reducing the net CO2 uptake rate and the photochemical quantum yield of both photosystems (PS). Two-dimensional imaging analysis of the chlorophyll fluorescence signal of PS II revealed that the yield reduction spread basipetally via the veins through the leaf at a speed of 1.6 ± 0.3 mm s−1 while the propagation speed in the intervein region was c. 50 times slower. Propagation of the signal through the veins was confirmed because PS I, which is present in the bundle sheath cells around the leaf vessels, was affected first. Hence, spreading of the signal along the veins represents a path with higher travelling speed than within the intervein region of the leaf lamina. Upon the electrical signal, cytoplasmic pH decreased transiently from 7.0 to 6.4, while apoplastic pH increased transiently from 4.5 to 5.2. Moreover, photochemical quantum yield of isolated chloroplasts was strongly affected by pH changes in the surrounding medium, indicating a putative direct influence of electrical signalling via changes of cytosolic pH on leaf photosynthesis. 相似文献
68.
ALESSANDRA FIDELIS GERHARD E. OVERBECK VALÉRIO D. PILLAR JÖRG PFADENHAUER 《Austral ecology》2009,34(5):558-566
The role of facilitation in the structuring of plant communities has been often demonstrated in environments under high abiotic stress, especially in semi‐arid and arid ecosystems and high elevations. Few studies, however, analysed facilitation in systems that are highly productive and rich in species, which are thought to be theoretically unlikely to demonstrate strong effects of facilitation. Here, we investigate the importance of Eryngium horridum, a rosette species, on the maintenance of plant diversity in subtropical grasslands in southern Brazil. We evaluated facilitation in areas under two different types of management: abandonment and grazing. Plots were established in areas with and without individuals of E. horridum and all species were identified and had their cover estimated. The Relative Neighbour Effect index was calculated in order to verify the presence of competition or facilitation. Our results indicated facilitation in both abandoned and in grazed grasslands, but apparently through different mechanisms. In the first case, the plant's architecture opens the canopy and allows more light to reach small forbs in the grass matrix. In the second case, E. horridum appears to protect more palatable species from herbivores. Otherwise considered an obnoxious species, E. horridum plays an important ecological role in subtropical grasslands in southern Brazil by facilitating other species and consequently, increasing local richness. Areas with this rosette species are important sources of diaspores, which are able to colonize new open sites and thus, maintain biodiversity. 相似文献
69.
VANSELOW KLAUS HEINRICH; KOLBOWSKI J?RG; HANSEN ULF-PETER 《Journal of experimental botany》1989,40(2):247-256
Linearization is an efficient means of detecting individualcomponents in complex fluorescence induction curves. In a previousinvestigation based on sine-waves (Hansen, Kolbowski, and Dau,1987) the components related to the plastoquinone pool, thehigh-energy state of the thylakoid membrane and the state 1-state2 transition controller could be identified. In this paper,binary noise is used as an alternative input signal which canalso allow linearization by mathematical tools. Comparison withexperiments using sine-waves shows that curve-fitting of thenoise experiments yields the same data as the sine-wave analysis.Further, some additional components were revealed as labelledby the related time-constants whose values depended on lightintensity (e.g. 5, 15, 20, 70, 85, 550 s for spinach at 2.5W m2). The advantages of noise analysis are a shorter measuring time and the availability ofan on-line criterion which indicates when a sufficient signal-to-noiseratio is reached. Key words: Chlorophyll fluorescence, correlation functions, linearization, noise, spinach, time-constants 相似文献