题干

近年来在疫苗家族中增加了第三代疫苗﹣﹣DNA疫苗,它们由病原微生物中的一段表达抗原的基因制成,这段基因编码的产物仅是引起机体的免疫反应.以下关于DNA疫苗的叙述正确的是(    )

A:能引起特异性免疫反应是因为DNA疫苗是抗原

B:DNA疫苗引起免疫反应前必须经过转录和翻译的过程

C:DNA疫苗导入人体后,浆细胞分化为记忆细胞

D:接种后若感染此病原微生物,则体内记忆细胞会产生大量抗体

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答案(点此获取答案解析)

B

同类题3

阅读理解

     An Iowa elementary school principal was taped onto a gym wall by his students on Friday,November 5th,2014.Principal Ryan Castle of Colorado Elementary School in Iowa,America let 27 students in his school tape him to a gym wall.He stayed up there,with his both feet suspended(悬浮) above the floor,from the morning until lunch time.

     Ryan Castle earlier promised to the students that if they sold 10,000 fall festival tickets,he agreed to be taped onto a gym wall at his school.Unexpectedly,the students had sold 11,000 fall festival tickets by October the 31st.He kept his promise and he let the students tape him onto a gym wall.

     Twenty-seven top-selling students were allowed to tape Ryan Castle up.Ryan Castle was photographed wearing a fake mustache because it was Mustache Day for the school.It was not the first time that principals were taped onto a wall in America.Ryan Castle's case comes after at least three other recent cases of school principals being taped up on the wall for a good cause.

     On last Wednesday,Jay Woller of La Crescent Elementary School in Minnesota America was taped onto a wall after $21,000 was collected by his students through fundraising.And last month,Randy Ten Pas of Hull Christian School in Iowa America was taped onto a wall with duct tape.He was taped on a 300-feet-tall building wall in his school—as a symbolic reward for students' fundraising efforts coming to $3,300.Randy Ten Pas was photographed wearing a green cap and with a drawing of the Denver Broncos logo(商标) next to him.At St.Mary Catholic School in Orange,Texas,principal Donna Darby offered a similar ticket-selling challenge to students in September.He was also taped onto the wall in the end.They kept their word and set good examples to their students.

同类题4

阅读材料,完成下列要求。

材料一:“开窗见河,出门过桥”的江南水乡双林镇,元明以来,史载“吴丝衣天下,聚于双林。吴、越、闽、番至于海岛,皆来市焉。五月载银而至,委积如瓦砾。”“吾镇之乡村无不栽桑”,“近镇数村,以织绢为业,男子或从事绞线,常出市买丝卖绢”。外来商人形成规模,出现了泾县会馆、宁绍会馆等。随着外来定居的商人通过家族繁衍和科举考试成为本地的缙绅,地缘关系和血缘关系都较前大为减淡。士绅并不像某种“经纪”或者“代理人”,他们似乎在这个官府不在场的地方扮演着官府的角色。崇善堂等地方慈善组织逐渐向地方自治组织转化,基于共同利害的社区认同

开始形成

——据赵世瑜《市镇权力关系与江南社会变迁》等

材料二:中世纪晚期以来,几乎所有威尼斯人都是商人,他们的活动使得地中海的商业网络扩大,甚至进入中亚、印度和中国去寻找商业机遇。威尼斯货币是当时欧洲普遍流通的货币。银行家们向从事远距离贸易的商人发放信贷凭证,商人们发明了分散商业投资的新方法,有限责任促进了商业合伙关系的形成。关于债务、破产等的商业习惯法得到推广。威尼斯还成立了城市共和国,他们自己管理城市事务。每一种公共设施都可在威尼斯找到典范:退休公务人员的年金制,对孤寡的照顾,医院的医疗福利制度等等。威尼斯作为“自由的长女,闪烁着自由之光的童贞城市”,堪称世界上早期第一个近代化(城市)国家

——据【美】本特利《新全球史》等