单选题下列哪个是人体非必需氨基酸

单选题成熟hDL中含量最多的物质是

单选题根据F.Crick中心法则，遗传信息的传递方式是

单选题 下列哪项不是连接矩阵法表示网络的优点（ ）。 A、表示直观 B、易于表示有向网络 C、易于表示边的权重 D、计算机存储空间小

单选题下列辅酶中含有维生素B2的是

单选题下述物质哪一个是细胞色素氧化酶

单选题Low levels of literacy and numeracy have a damaging impact on almost every aspect of adults, according to a survey published yesterday, which offers (1) of a developing underclass. Tests and (2) with hundreds of people born in a week in 1958 graphically illustrated the (3) of educational underachievement. The effects can be seen in unemployment, family (4) , low incomes, depression and social inactivity. Those who left school at 16 with poor basic skills had been employed for up to four years less than good readers (5) they reached 37. Professor John Bynner, of City University, who carried the research, said that today’s (6) teenagers would even encounter greater problems because the supply of (7) jobs had shrunk. Almost one fifth of the 1,700 people interviewed for yesterday’s report had poor literacy and almost half (8) with innumeracy, a proportion (9) other surveys for the Basic Skills Agency. Some could not read a child’s book, and most found difficult (10) written instruction. Poor readers were twice as likely to be a low wage and four times likely to live in a household where partners worked. Women in this (11) were five times as likely to be (12) depressed, (13) both tended to feel they had no control over their lives, and to trust others (14) . Those who had low literacy and numeracy were seldom (15) in any community organization and less likely than others to (16) in a general election. There had been no (17) in the literary level of (18) reporting problems. Alan Wells, the agency’s director, said: “ The results emphasize the dangers of developing an underclass people, who were out of work, (19) depressed and often labeled themselves as (20) . There is a circle of marginalization, with the dice against these people and their families.”

单选题下述哪项决定基因表达的时间性和空间性

单选题A．DNA复制或转录时模板链的方向B．DNA复制时前导链的方向C．DNA复制叉的前进方向D．DNA复制时冈崎片段的方向E．DNA或RNA合成时核酸链的延伸方向

单选题将血清蛋白质置于pH 8．6缓冲液中进行醋酸纤维薄膜电泳时，可从正极到负极出现下列五条区带，其中排列顺序恰当的是

单选题只能在线粒体进行的代谢途径是

单选题肝内调节糖分解或糖异生反应方向的主要信号是

单选题下列哪种碱基，只存在于RNA而不存在于DNA中?( )

单选题下列各项中，不属于真核生物基因表达转录前水平调节的过程是______。 A．RNA编辑 B．染色质丢失 C．染色体DNA的修饰和异染色质化 D．基因重排

单选题脂肪合成的场所是

单选题胰岛素分子A链和B链的交联是靠

单选题胆固醇来源于磷酸戊糖途径的合成原料是

单选题氮杂丝氨酸能干扰或阻断核苷酸合成是因为其化学结构类似于

单选题 对于涉及50万SNP的基因组范围关联研究，使用Bonferroni方法进行多重检验校正一般将阈值定为（ ）。 A、0.05 B、0.01 C、 D、

单选题6-磷酸果糖激酶-1的最强别构激活剂是