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具有硬实时上限的离散事件系统的建模 被引量:1
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作者 李惠峰 卫军胡 +1 位作者 陈浩勋 孙国基 《西安交通大学学报》 EI CAS CSCD 北大核心 1998年第7期27-31,共5页
实时离散事件系统中有两种具有硬实时上限的离散事件———有界事件和有效期事件,它们比基本实时离散事件———无界事件和强迫事件具有更强的时间约束,对包含这两类事件的系统进行研究就变得十分复杂.文中给出了基于基本实时离散事... 实时离散事件系统中有两种具有硬实时上限的离散事件———有界事件和有效期事件,它们比基本实时离散事件———无界事件和强迫事件具有更强的时间约束,对包含这两类事件的系统进行研究就变得十分复杂.文中给出了基于基本实时离散事件的Petri网模型,并为有界事件和有效期事件找到了由基本实时离散事件构成的Petri网模型,从而使文中的模型能够描述更广泛的离散事件系统. 展开更多
关键词 实时离散事件系统 有界事件 有效期事件 tick事件 PETRI网模型 硬实时上限
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Anti-tick activity of some methanol plant extracts indigenous in Saudi Arabia
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作者 KhaledB.Al-HARBI IbrahimM.El-ASHMAWY HusseinM.OMAR 《中国药理学与毒理学杂志》 CAS CSCD 北大核心 2015年第S1期112-113,共2页
OBJECTIVE Ticks are economically important parasites all over the world.They are vectors of different animal and human infectious diseases.Tick control is globally based on chemical acaricides,but the developing tick ... OBJECTIVE Ticks are economically important parasites all over the world.They are vectors of different animal and human infectious diseases.Tick control is globally based on chemical acaricides,but the developing tick resistance to most of the currently used synthetic acaricides encouraged to look for alternative ways to control ticks,especially natural products that are relatively environment friendly.METHODS An in vitro screening of the effects of some indigenous plants was carried out.Twenty-one plant species were extracted and tried to have effects on the most prevalent tick species;Hyalomma drommederi of camels.Fully engorged female ticks of the same weight,were immersed in the different extracts for 5,15,30 and 60min.RESULTS Treated ticks were revived and incubated with the control groups for daily observation of their activity and egg production.While some plant extracts have killing effects after 30-60 min exposure(Rhanterium epapposum,Achillea fragrantissima and Eragrostis poaeodes)others have stopped oviposition(Artemisia herba alba,Haloxylon salicornicum,Plantago coronopus,Moltkiopsis ciliate and Lasiurus hirsutus).Most of the extracts have reducing effect on the egg mass.Marked reduction of the egg masses associated with delayed oviposition was recorded on exposure to Lepidium sativum seeds extract.CONCLUSION The phytoconstituents were determined by a standard methods and further studies are on going to determine the bioactive components that may have the above mentioned acaricidal effects. 展开更多
关键词 ticks Hyalomma drommederi PLANT EXTRACTS ovipositi
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