简介:1.抱腿拱膝法女子被迫倒地以后,一般来讲,都比较紧张。但这时应冷静,除了大声呼救以外,还可利用力学原理,根据具体情况选择一些防身自救方法。歹徒如图1那样将我拖倒在地。我在倒地挣扎的过程中抱住歹徒离我身体最近的一只脚(图2),利用身体下倒的惯性猛地向前一顶,双手同时向后一拉,将十分容易地把歹待撞倒在地(图3)。2.夹腿翻滚法我被歹徒拖倒,位于其正前方(图4)。此时可趁其趋步上前欲按我之际,以左臂反挽歹徒离我最近的右腿(图5),手臂使劲夹住歹徒的小腿,身体向左方猛地翻滚一周,使其被迫向后摔倒(图6)。这种方法,实际上就是利用了“迫使重心和底基朝着相反的方向移动,使重心移出底基”的力学原理。3.剪腿法当歹徒用暴力将我推倒时,我尽可能采取侧姿对敌(图7)。当歹徒向前扑来的瞬间,可突然收腿呈剪刀式,左腿勾住其左脚外侧,右腿收起,别住其右侧髋关节(图8)。左腿向前,右腿向后,猛地剪动,使歹徒重心向左移,底基向右移而被迫向侧后摔倒(图9)。4.挫蹬腿倒地时若是仰面对敌也勿须惊慌,须冷静观察其行(图10)。待歹徒俯身前扑的瞬间,身体突然向左翻转,以右掌挥击其耳门(图11)。不管打中与否,翻转的左脚都要立即...
简介:1994年2月4日,日本成功地发射了第一枚H—Ⅱ运载火箭。这次发射成功预示着日本的宇航事业美好的发展前景。H—Ⅱ运载火箭将做为日本九十年代到下世纪初的主要空间运载系统。它最显著的技术特点主要体现在它的第一级发动机LE—7和第二级发动机LE—5A。这两种发动机均以液氢为燃料,液氧为氧化剂。独特的发动机设计特点,使得H—Ⅱ运载火箭跻身于世界航天技术行列中并成为其中的佼佼者。LE—7和LE—5A是以LE—5发动机的技术为基础发展起来的。LE—5发动机是完全依靠日本技术研制出的第一种低温发动机,并成功地应用在H—Ⅰ运载火箭的第二级上。本文着重介绍日本低温发动机研制的历史,展示这些发动机独特的设计以及研制中所遇到的技术问题。
简介:AbstractObjective:The prevalence of midline birth defects, such as gastroschisis, has increased worldwide, over the last few decades. This study aims to explore the prevalence, maternal epidemiological characteristics, and natural history of neonates affected by gastroschisis at the University Hospital of León city, Nicaragua.Methods:Data were collected from the birth defect surveillance system of the Hospital Oscar Danilo Rosales (HEODRA). The analysis included all pregnancies that had gastroschisis complications between January 1 and December 31, 2020. The prevalence of gastroschisis was calculated according to maternal age. The mothers were interviewed, and the clinical records of the newborns were reviewed.Results:Among the 4,460 deliveries included in this study, four cases of gastroschisis were identified, including three live births and one stillbirth. The gastroschisis rate was 8.9 per 10,000 live births (95% confidence interval [CI]: 0.18-17.8). The prevalence among mothers younger than 20 years and those older than 20 years was 26.4 (95% CI: -3.43 to 56.25) and 3.01 (95% CI: 2.89-8.90)/10,000 births, respectively. Mothers of gastroschisis-affected fetuses were of rural origin (n = 3), had normal body mass indexes (n = 3), were exposed to tobacco and wood smoke (n = 2), and one was exposed to pesticides during the periconceptional period. Primary closure of the gastroschisis was performed on one patient, and complex gastroschisis for intestinal perforation was observed in another patient. The mean hospitalization duration was 33 days, and two patients were discharged alive.Conclusions:Gastroschisis was a significant birth defect among children delivered at HEODRA in 2020. Its prevalence in Nicaragua was higher than that in other countries in the region. All complicated pregnancies were young women with unplanned pregnancies, from rural areas, with exposure to secondhand smoke, and without vitamin supplements before or during the first trimester of pregnancy. Only 67% of infants survived after hospital discharge.