Rubidium, potassium and carbon are
three common elements used to date the history of Earth. The rates of
radioactive decay of these elements are absolutely regular when averaged out
over a period of time; nothing is known to change them. To be useful as clocks,
the elements have to be fairly common in natural minerals, unstable but decay
slowly over millions of years to form recognizable "daughter" products which are
preserved minerals. For example, an atom of radioactive rubidium decays to form an atom of strontium (another element) by converting a neutron in its nucleus to a proton and releasing an electron, generating energy in the process. The radiogenic daughter products of the decay-in this case strontium atoms--diffuse away and are lost above a certain very high temperature. So by measuring the exact proportions of rubidium and strontium atoms t A. the number of the mineral pores B. the number of missing argon atoms C. external temperature D. mineral temperature [单选题]引起血浆凝血酶原时间延长的疾病是( )
A.心肌梗死 B.多发性骨髓瘤 C.严重肝病 D.脑血栓形成 E.深静脉血栓形成 [单项选择]流行性脑脊髓膜炎的病理变化有()。
A. 筛状软化灶 B. 血管周围淋巴细胞套袖状浸润 C. 蛛网膜下腔大量炎细胞渗出 D. 脑底部病变最显著 E. 脑实质受累 [多选题]压盖机组成( )
A.A.套盖头 B.B.套盖机座 C.C.传动齿轮 D.D.盖滑道 E.E.电眼等清洁无污垢 [单项选择]在Windows98中,若不使用鼠标,按( )键可以打开“开始”菜单。
A. Ctrl + Esc B. Ctrl+Tab C. Esc D. Tab [多项选择]价值规律的内容和要求是( )。
A. 价值量由社会必要劳动时间决定 B. 价值量由耗费的劳动时间决定 C. 商品按等价原则进行交换 D. 价格围绕价值上下波动 [简答题]动机强度越高,越有利于取得成功。
[单选题]治疗缺铁性贫血的最后目标是
A.血红蛋白正常及补足骨髓贮存铁 B.血红蛋白及血清铁恢复正常 C.红细胞形态回复正常 D.血清铁及血清铁总结合力恢复正常 [简答题]国库的同城票据应通过何科目反映,需要挂账时使用何科目、何账户进行账务处理?
[判断题]党员如果没有正当理由,连续5个月不交纳党费,就被认为是自行脱党。
A.正确 B.错误 [简答题]简述氩馏分对氧氮产品纯度的影响。
[不定项选择]下面关于股利政策的阐述正确的是()。
A. 股利政策是指股份公司对公司经营获得的盈余公积和应付利润采取现金分红或派息、发放红股等方式回馈股东的制度与政策 B. 分红派息是股票投资者经常性收入的主要来源 C. 送股实质上是留存利润的凝固化和资本化,表面上看,送股后,股东持有的股份数量因此而增长,其实股东在公司里占有的权益份额和价值均无变化 D. 在我国,投资者获上市公司送股时也需缴纳所得税,目前为20% 我来回答: 提交
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