共查询到20条相似文献,搜索用时 15 毫秒
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《Reports of Practical Oncology and Radiotherapy》2002,7(2):53-60
PurposeTo improve the reproducibility of patient positioning in fractionated irradiation and to achieve uniform irradiation of the patient, within 12–15Gy, excluding the lungs.MethodTwo special body frames were manufactured, one for treatment planning and the other for the treatment itself. Special tin markers were inserted in the walls to make it possible for a patient to maintain the same position during each fraction of irradiation. Patient treatment was carried out in six fractions (four lateral and two AP/PA fields), twice a day, over three consecutive days. The lungs were shielded during AP/PA fractions and during one lateral fraction. The shape of the shields for AP/PA fields was determined with the use of computer tomography scans, and for lateral fields on the basis of radiographic pictures taken by a simulator. The doses calculated at some selected anatomical points for every patient were checked by in vivo measurements which were carried out by means of MOSFET detectors.Results and conclusionsReproducibility of patient positioning during consecutive treatments and a uniform total dose distribution over the range of 12 – 15 Gy (except in the lungs) have been achieved. This has been confirmed by in vivo measurements. 相似文献
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Herbert William Allingham 《BMJ (Clinical research ed.)》1889,1(1480):1086-1087
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The objective of the studies was to analyse the process of oogenesis in vimba from a non-migratory population living in the waters of Drawieński National Park in north-west Poland. The character of spawning of this species is an obstacle in determining the right moment to catch spawners or developing artificial spawning biotechniques. Previtellogenesis of vimba begins about six months after hatching and lasts three years. The trophoplasmatic growth of oocytes (October-March/April) begins when carbohydrate vesicles appear near the nuclei oocytes of sexually mature females (aged 4+). Just before spawning, granulated, lipoprotein-like substances are cumulated. The resorption of pre-ovulation corpora lutea (non-ejected oocytes) and post-ovulation corpora lutea (ruptured theca folds and follicles) begins in the ovary of vimba in the middle of June. These were observed in histological cross sections for about two to three months. Describing the process of oogenesis can provide a foundation for developing practical applications in aquaculture aimed at preserving the biodiversity of the park's waters and this critically endangered species of the Polish ichthyofauna. 相似文献
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Marcin Rapacz 《Acta Physiologiae Plantarum》1998,20(1):73-78
Experiments performed under controlled conditions showed that level of PPFD (photosynthetic photon flux density) during early
seedlings growth (preceding cold acclimation at +2 °C) was not the key factor for the development of frost resistance. It
did not modify the beneficial effects of prehardening (Rapacz 1997, in this issue) at moderately low (+12 °C) day temperature.
Now I have shown that the increase of PPFD may replace to some extent prehardening in the development of frost resistance.
It was particularly seen in non-prehardened plants, which had been grown under warm-day (+20 °C) conditions.
Prehardening performed under controlled conditions, as well as seedlings growth under natural autumn conditions in the field,
allowed to maintain a high net-photosynthesis rate at chilling temperatures. A net-photosynthesis rate during cold acclimation
at +2 °C corresponded well with higher frost resistance. As a result, seedlings non subjected to prehardening and grown before
cold acclimation under low PPFD acclimated better, if the cold treatment was applied only at nights (+20/2 °C day/night).
Only under such conditions the photosynthetic rate was sufficiently high to allow plants to reach a higher level of frost
resistance. All other plants acclimated better when they were exposed to the hardening temperature continuously during days
and nights (+2/2 °C day/night). 相似文献
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《Medizinische Genetik》2012,24(1):48-51
Personalia
Ein Portr?t von Prof. Dr. Dr. h. c. Wolfgang Engel 相似文献19.
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In this paper we present the effects of environmental factors and zooplankton food pressure on phytoplankton in the restored man-made Maltański Reservoir (MR). Two methods of restoration: biomanipulation and phosphorus inactivation have been applied in the reservoir. Nine taxonomical groups of phytoplankton represented in total by 183 taxa were stated there. The richest groups in respect of taxa number were green algae, cyanobacteria and diatoms. The diatoms, cryptophytes, chrysophytes, cyanobacteria, green algae and euglenophytes dominated in terms of abundance and/or biomass. There were significant changes among environmental parameters resulting from restoration measures which influenced the phytoplankton populations in the reservoir. These measures led to a decrease of phosphorus concentration due to its chemical inactivation and enhanced zooplankton grazing as a result of planktivorous fish stocking. The aim of the study is to analyse the reaction of phytoplankton to the restoration measures and, most importantly, to determine the extent to which the qualitative and quantitative composition of phytoplankton depends on variables changing under the influence of restoration in comparison with other environmental variables. We stated that application of restoration methods did cause significant changes in phytoplankton community structure. The abundance of most phytoplankton taxa was negatively correlated with large zooplankton filter feeders, and positively with zooplankton predators and concentrations of ammonium nitrogen and partly of phosphates. However, restoration was insufficient in the case of decreasing phytoplankton abundance. The effects of restoration treatments were of less importance for the abundance of phytoplankton than parameters that were independent of the restoration. This was due to the continuous inflow of large loads of nutrients from the area of the river catchment. 相似文献