单选题下列关于嵌合体的说法，不正确的是( )。

单选题最不稳定的RNA是( )。

单选题脂酸p-氧化过程中脂酰CoA所脱下的氢由下列哪些辅助因子接受

单选题以下哪种修复机制不需要DNA聚合酶活性：

单选题A．己糖激酶B．磷酸化酶C．6-磷酸葡萄糖脱氢酶D．丙酮酸羧化酶E．异柠檬酸脱氢酶

单选题The objective of the migrant health program of the United States government is to provide grants for the development and enhancement of high quality health care services in rural areas for migrant and seasonal farm workers and their families so as to raise the status of health care for these people to that of the general population. This amelioration can be achieved by providing comprehensive heahh services, which are made aeeessible to people who move frequently, and by improving the physical environment so as to assure healthful living and working conditions wherever workers are located. Grants are available to state and local health departmenls and other nonprofit agencies, organizations, and institutions. These funds can he used for the following purposes: to establish and operate general family health service facilities and clinics; to provide heahh education, training, and sanitation services to upgrade health conditions; and to initiate preventive health services. Preventive care in the form of immunization programs is the oldest aspect of the program. The program further attempts to promote flexibility in locating health services where they will be accessible at times and places convenient to migrant workers and their families. The family heahh care clinic, with additional outreach services by field nurses and aides who visit migrant families in camps and at their homes for counseling and follow-up, constitutes the newest and most significant innovation in the initiate preventive health services. However, despite the introduction of innovative approaches, heahh care services for migrant workers are still limited and highly inadequate. Although the migrant health program has no fixed matctling ratio, a grantee is required to pay part of the cost, which varies from project to project. Many rural counties do not have enough money to cover matching payments, nor do many states consider migran! workers' health a budget priority. The costsharing requirement limits the potential effectiveness of the program, and literally hundreds of communities with a yearly influx of nngrant workers still lack organized local programs to provide the needed services. A major problem for local or state health agencies is their inability to develop case histories and ongoing communication with migrant workers. Lack of knowledge regarding migrant workers' health needs is another reason for the dearth of services. There has been little communication about health problems among communities, health professionals, and migrant workers themselves. Ignorance of a group's special needs often leads to exclusion and rejection of that group and its prohlems. This is often the case with migrant workers, as evidenced by the enforcement of state residency requirement. It is, of course, impossible for most migrant workers to meet these requirements and become eligible fro" existing state and local heahh and welfare aid.

单选题调节氧化磷酸化的最主要的因素是 A.氰化物 B.解偶联剂 C.Cyt aa3 D.[ADP]/[ATP] E.甲状腺素

单选题多胺是由哪一种氨基酸脱羧基生成的

单选题A．透析与超滤法 B．盐析C．超速离心 D．凝胶过滤E．电泳

单选题在细菌中，一种RNA聚合酶负责______的合成。

单选题与RNA聚合酶相识别和结合的DNA片段是______ A.增强子 B.衰减子 C.沉默子 D.操纵子 E.启动子

单选题维生素C对含巯基酶的保护作用是

单选题切口平移是指在( )作用下，使( )带上放射性标记。

单选题RNA聚合酶的结合位点是( )。

单选题下列化合物中哪个不含环状结构?______

单选题能与原核生物操纵序列结合介导负性调节的蛋白质是

单选题酶活性测定的反应体系的叙述正确的是 (　　　)

单选题关于超氧化物歧化酶的捕述，不正确的是 A.可催化产生超氧离子 B.可消除超氧离子 C.含金属离子辅基 D.可催化产生过氧化氢 E.存在于细胞质和线粒体中

单选题经脱羧基作用后生成γ一氨基丁酸的是

单选题可被Ca 2+ 激活的是