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61.
周延清  贾敬芬 《广西植物》2004,24(5):466-470
该文旨在研究通风在不同好好吧无性系芽增殖阶段对它们增殖体的叶面积、地上部分总面积和失水能力的作用,筛选抗旱性好的好好吧无性系。研究结果表明,在13个好好吧无性系中,通风使他们的叶面积、总面积和抗失水力均有增加。其叶面积分别增加了72.2%到470.5%,其总面积分别增加了39.0%到145.8%,其抗失水力分别增加了(失水分别减少了)22.2%到138.0%。从中选择了一个叶面积和总面积都增加最多(分别为470.5%与145.8%)和失球减少次多(86.7%)的耐旱好好吧无性系CQ63,可供沙漠和旱地种植。  相似文献   
62.
Thermo-osmotic gas supply not detected in Avicennia marina seedlings   总被引:2,自引:0,他引:2  
Ethane was used as tracer gas to assess the likelihood of thermo-osmotically induced mass-flow in the aerenchyma of Avicennia marina seedlings without pneumatophores. Ethane movement was measured in darkness and with illumination at approximately 600 µ mol m–2s–1 provided to the leaves and stem, with the expectation that leaf warming under illumination would provide for thermo-osmotic flow. In some seedlings the flow increased with illumination, and in others it either decreased or remained unchanged. Overall, there was no statistically significant difference in the conductance to ethane between darkened illuminated plants, and the rates of ethane movement were consistent with an average diffusive conductance to oxygen down the stem of 0.22 × 10–19m3 s–1. it was concluded that there was no evidence for thermo-osmotically induced in this case.  相似文献   
63.
64.
Summary A technical approach, in terms of air quality, implies the review of all components within the air conditioning system and the check of their characteristics, as far as contamination sources are concerned. The contribution introduces the parameters to be examined and specifies the importance of validation.  相似文献   
65.
66.
《Journal of morphology》2017,278(8):1075-1090
Musculo‐skeletal morphology is an indispensable source for understanding functional adaptations. Analysis of morphology of the branchial apparatus of Hexanchiform sharks can provide insight into aspects of their respiration that are difficult to observe directly. In this study, I compare the structure of the musculo‐skeletal system of the gill apparatus of Heptranchias perlo and Squalus acanthias in respect to their adaptation for one of two respiratory mechanisms known in sharks, namely, the active two‐pump (oropharyngeal and parabranchial) ventilation and the ram‐jet ventilation. In both species, the oropharyngeal pump possesses two sets of muscles, one for compression and the other for expansion. The parabranchial pump only has constrictors. Expansion of this pump occurs only due to passive elastic recoil of the extrabranchial cartilages. In Squalus acanthias the parabranchial chambers are large and equipped by powerful superficial constrictors. These muscles and the outer walls of the parabranchial chambers are much reduced in Heptranchias perlo , and thus it likely cannot use this pump. However, this reduction allows for vertical elongation of outer gill slits which, along with greater number of gill pouches, likely decreases branchial resistance and, at the same time, increases the gill surface area, and can be regarded as an adaptation for ram ventilation at lower speeds.  相似文献   
67.
The examples and clinical cases presented in this section are not intended to be considered as absolute models in terms of image quality or device parameter settings. They must initiate an individual analysis according to CT parameters and image quality. Nevertheless, they present practically different CT levels, which can be used according to the clinical context and the type of device.  相似文献   
68.
The relative timing between operculum and pectoral fin motion was examined in swimming bluegill Lepomis macrochirus to determine if respiratory fluid flows from the operculum might have an effect on flow over the pectoral fin. Five bluegill were filmed swimming at speeds from 0·5 to 1·5 body (total) lengths s−1. The timing of opercular pumping and pectoral fin beating was noted and analysed using circular statistics. Fish tended to ventilate their gills every second or third pectoral fin beat. While locomotion and ventilation had different frequencies, however, they were synchronized: fish maintained a consistent phase relationship between them. Thus, within pectoral fin beats when the operculum pumps, the jet consistently occurred during pectoral fin abduction, ending just after the fin was fully abducted and beginning adduction. Based on the distance between the opercular slit and the pectoral fin base, the jet was estimated to reach the fin during maximum abduction. Dye flow visualization confirmed this estimate, revealing that the opercular flow wraps around the base of the fin during peak abduction, when it is likely to have little hydrodynamic effect.  相似文献   
69.
Zusammenfassung Das respiratorische Epithel der Tracheenkiemen ist durch ein hochgeordnetes Tracheolengerüst charakterisiert. Die Tracheolen liegen parallel zur Längsachse der fadenförmigen Tracheenkiemen dicht unter der Cuticula in statistisch gleichmäßigem Abstand zueinander. Die Regelmäßigkeit dieses subcuticularen Tracheolengerüsts weist auf ein physiologisch optimal arbeitendes System hin. Der Abstand zwischen zwei Tracheolen ist sehr wahrscheinlich gleich dem doppelten Radius der tracheolaren Einzugsgebiete. Auf diese Weise wird bei einem Minimum an Tracheolenmaterial der gesamte diffundierende Sauerstoff der respiratorischen Oberfläche von den Tracheolen erfaßt. Die Morphogenese dieser Strukturregelmäßigkeit wird während der larvalen Entwicklung verfolgt. Dabei zeigt sich, daß mit jeder Häutung zahlreiche neue Tracheolen in das respiratorische Epithel geordnet eingebaut werden und die Abstände zwischen den Tracheolen in Korrelation zum Radius der Tracheolen von Larvenstadium zu Larvenstadium geregelt abnehmen.
Morphogenesis of the respiratory epithelium in the tracheal gills of larval Limnephilini KOL. (Insecta, Trichoptera)
Summary The respiratory epithelium of the tracheal gills of the larval Limnephilini KOL. (Insecta, Trichoptera) is characterized by a highly organized tracheolar framework. The tracheoles are found parallel to the longitudinal axis of the thread-like tracheal gills and lie closely underneath the cuticle at statistically uniform distances. The regular distribution of the subcuticular tracheoles represents an optimum physiological system with the tracheolar interspace probably corresponding to twice the radius of the tracheolar catchment area. This arrangement ensures that all oxygen diffusing across the respiratory gill surface is taken up by the tracheoles with a minimum of tracheolar material. The morphogenesis of this regular distribution was studied during the larval development. With each moult numerous new tracheoles are added to the regular distribution. The distances between the tracheoles decrease regularly in correlation to the decreasing radius of the tracheoles from one larval stage to the next.
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70.
The involvement of ethylene in the vitro development of shoots from nodal segments of two cultivars of carnation (Dianthus caryophyllus L.) was studied. Shoots of cv. Barbaret Antares showed low hyperhydricity in contrast with the high levels showed by cv. Barbaret Tanga when both were cultured in airtight culture vessels. Longer shoots were produced, in both cases, when the rate of gas exchange in the culture vessel was increased by using vented closures, which also prevented hyperhydricity and increased the multiplication coefficient in cultures of Barbaret Tanga.The two cultivars produced ethylene throughout the culture period but, a higher amount was produced during the first, second and fourth weeks in culture by the cultivar more sensitive to ventilation (Barbaret Tanga). Trapping ethylene did not produce any effect on cv. Barbaret Antares but improved the quality of cv. Barbaret Tanga explants, decreasing hyperhydricity and increasing the number of shoots, the length of the main shoot and the multiplication coefficient. These effects were more marked when ethylene was trapped during the first two weeks in culture.  相似文献   
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