简介:摘要地面塌陷是采空区最主要的地质灾害,具有突发性、多发性、隐蔽性等特点,危害大且难以治理。本文通过阐述某矿区地面塌陷的特征,探讨其形成机理,并对塌陷危险性做出评价,从而提出相应的防治措施。通过对地面塌陷危险性研究,在立足塌陷本质的基础上,采取科学合理的防治措施可保证人类工程活动和建筑物的安全。
简介:需要长期避孕妇女;生殖道畸形不宜放置宫内节育器者。应用宫内节育器反复脱落或带器妊娠者;对服用含雌激素避孕药有禁忌证者;应用口服避孕药难以坚持者;己生育子女,需要长期避孕而不适宜绝育术有顾虑者。
简介:Dysmenorrheareferstoperiodiclowerabdominalpainoccurringduringoraroundmenstruation.Itoftenhappensbeforeorduringperiod,occasionallyafterperiod,andmanifestslowerabdominalpain,crampyordistending,whichmayradiatetolumbosacralregion,innerthighandperianalregion.Co-occurringsymptomsmayincludepalecomplexion,nausea,vomiting,diarrhea,andaversiontocoldinthewholebodyorconcentratedinlowerabdomen.Severepaincancauseprostrationorevenfainting.Menstrualpaincommonlylastsforseveralhoursor1-2d,andrelieveswhenmenstrualbloodflowssmoothly.