排序方式： 共有7条查询结果，搜索用时 31 毫秒
1
1.
Gianna Giachi Chiara Capretti Nicola Macchioni Benedetto Pizzo Ines Dorina Donato 《Journal of Cultural Heritage》2010,11(1):91-101
The aim of the work is to set up a methodological approach to verify the effectiveness of the treatments of decayed waterlogged archaeological wood and to point out the proper thermo-hygrometric conditions for its preservation after treatment. The treatments were performed on wood samples of maritime pine (Pinus pinaster Aiton), oak (Quercus sp. caducifolia), elm (Ulmus cf. minor) and strawberry tree (Arbutus unedo L.), obtained from stems pertaining to the original vegetation found in the excavation site of the Ancient Ships in Pisa (Italy), and dated from seventh century BC to second century AD The utilised products were: Polyethylene Glycols (PEG) of various molecular weights, a Polypropylene Glycol (PPG 425), Trehalose (α-D-glucopyranosyl-α-D-glucopyranoside), and their mixtures, and also a Hydroxypropylcellulose (Klucel). The main objective to be pursued by the treatments was considered the stabilisation of the original size and shape of samples. The various steps of this approach were: the execution of a preliminary diagnostic survey on untreated samples; the characterisation of treatment solutions ‘as such’ to establish the property to be monitored during the treatment; the evaluation of the main physical characteristics of wood after the treatment were determined. Among the latter, the coefficient of dimensional stability during the exposure to a series of selected thermo-hygrometric conditions and the retention of consolidants after the treatment. These two measurements allowed the definition of the ‘efficacy of a treatment’, φT, a new parameter firstly utilised in this work. It measures the stabilisation capability of the percent unit of retained product, and its value permits to put in evidence the consolidants that stabilise wood with the lowest amount of product. Conversely, it was not possible to measure the Anti-Shrink Efficiency (ASE), one of the most utilised parameters for the evaluation of treatments, because of the serious distortions and fractures observed in all the heavily degraded untreated samples. 相似文献
2.
Consumer demand for eSport and the growth of organized video game competitions has generated considerable attention from the sport, event, and entertainment industries. eSport therefore represents a novel and popular area for sport management academics to conduct research, educate students, and service industry. However, despite growth and acceptance by consumers and practitioners, academics debate eSport’s position within the domain of sport management, their debates largely concentrated around the question of whether eSport can be classified as sport. In this article, the authors argue for the inclusion of organized eSport events and competitions within sport management vis-à-vis eSport’s meeting certain defining criteria of sport in general. eSport’s connection to traditional sport and defining characteristics are addressed to support eSport’s role as a sport entertainment product recognized by industry as representing a substantial growth opportunity for sport and related organizations. As eSport continues to evolve, practitioners face managerial challenges that are similar to those in traditional sport, particularly in areas of governance and diversity. Sport management academics should embrace the potential of eSport in order to examine this evolution and provide guidance to industry through education and research. 相似文献
3.
The objective was to determine whether rats could learn to time a 48-h interval. Rats (n = 6) were continuously housed in operant chambers in constant darkness. The feeding cycle consisted of unlimited access to
food for 6 h, followed by 42 h without access to food (i.e., meals were available on alternate days, contingent on breaking
a photobeam in the food trough). Head entries into the trough increased as a function of time prior to the meal; this increase
was higher, relative to the increase that occurred at the same time of day on alternate (i.e., nonfood) days. These data suggest
that rats discriminated alternate days. Next, two meals were omitted to dissociate mechanisms of a self-sustained endogenous
rhythm, interval timing, and alternation. Response rate increased periodically every 24 h, which suggests that the rats anticipated
alternate days by discriminating the status of the previous day as a meal or a nonmeal day. 相似文献
4.
5.
本文是一篇有关斯坦福大学医学院及其教学医院发展与改革的案例研究.本文论述了导致改革的背景因素和问题,改革的设想和实施过程,改革的现状和面临的挑战,以及某些经验教训.虽然现行模式正在运行中,为了对内部和外部的力量与领导改革作出响应,未来的改革也许是需要的. 相似文献
6.
7.
The conditions under which circadian and interval-timing mechanisms are used in time-place discrimination were investigated.
Rats earned the first daily meal by pressing a lever beginning 3.5 h after the start of the session and a second daily meal
by pressing another lever. The second meal started 3.5 or 7 h (Experiment 1) or 0.75 or 1.75 h (Experiment 2) after the start
of the first meal, using independent groups. In Experiment 1, approximately half of the rats used an interval-timing mechanism,
and the other half used a circadian mechanism. In Experiment 2, the rats timed two intervals, one from the start of the session
until the first meal and the other from the first to the second meal. A circadian mechanism is relevant to timing intervals
in the range of 1.75–3.5 h, and an interval-timing mechanism can be used to time intervals from 0.75–7 h. 相似文献
1