半衰期

Internal dosimetry is an uneasy task in nuclear medicine due to the variation of biokinetics in individual patients despite of the short half-life of radiopharmaceuticals and known physical and chemical characteristics.

核子医学之放射性药物的半衰期虽然都很短，而且其进入体内时之活度、物理形态、化学形态等均系已知，但因个别病患之新陈代谢数据的差异仍大，因此评估体内剂量也不甚容易。

The half-life and detection limit of abundance allows cosmogenic 129I dating within range of 80Ma.

半衰期和丰度探测下限水平允许宇生129I可测年的时间尺度为80Ma。

Accelerator mass spectrometry has ultra-high sensitivity and can be used to detect extremely low impurity contents in samples. 10Be is a cosmogenic nuclide. As a tracker, it has been widely applied to earth, environmental and cosmographic sciences.

加速器质谱计具有很高的灵敏度，能测量样品中含量极微的杂质同位素。10Be是一种宇宙成因核，在地学、环境科学和宇宙学等领域有广泛的应用，它为纯β衰变核，端点能量低且半衰期很长。

Ca is widely abundant in nature and its rodioisotope 41 Ca is a cosmogenic nuclide with a half\|life of 10 5 years. However, the 41 Ca/ 40 Ca ratio in natural samples is very low and can only be measure d by accelerator mass spectrometry. The application of 41 Ca is ve ry i mportant not only in the life science but also in geological dating, global envi ronment change studies and astrophysics.

1 引言Ca在自然界中广泛存在，它不仅是人体中含量最丰富的元素之一[1] ，也是众多其他物质的组成部分。41Ca(半衰期为 1.0 3× 10 5a)属于Ca的放射性同位素中的一种，其衰变方式为轨道电子俘获，只发射3.3keV的X射线，天然样品中41Ca 40 Ca的值很小。

The activation energies were highly pH-depended and decreased very sharply as the pH went up from 6. 0 to 11. 0 or down from 6. 0 to 2. 0.The stability of Gln residues in peptides or corn protein was the most at pH6. 0.At pH 6. 0, the rate constants of deamidation were the lowest, and their half-life and Arrhenius activation energies were the highest.

过酸或过碱都将增加脱酰胺反应的速率，动力学结果表明，pH6.0时最为稳定，表现为pH6.0时的脱酰胺反应速率常数最小、半衰期最长、活化能最大。

But NO is a hardly dissolvable gas, it's half-time in tissue is only about 10 seconds.

但NO是一种极难溶于水的气体，其在组织中的半衰期仅有10-60s，其反应活性取决于它被去除或破坏的速度。

The lowest was in the heart. The eliminative speed also had difference in different tissues. T1\2b was the highest in the spleen, then in the liver and kidney.

稀土进入组织后消除速度也因组织不同而有所差异，消除半衰期以脾最高、其次是肝和肾。

However, after two months, should stimulate reaction to cross half-life gradually, intermediary focusing also is met gallop decline, survival people day feeling loneliness and Bei are bitter, psychological crisis because this is fascicular break out, so that lead to 2 degrees of tragedy.

然而，两个月之后，应激反应渐过半衰期，媒介的聚焦也会驰衰，幸存者们日感孤独与悲苦，心理危机因此丛生突发，以至于酿成二度悲剧。

A series of P-T tests in field and model bin were carried out,through controlling initial pressure upper limit P and gastight degree,The results showed that gastightness not only relates to airtight degree,structure material and technological quality,but also relate to pressure upper limit,temperature and so on.

文章通过控制初始压力上限P和气密程度，进行了一系列P -T试验，对室内模拟仓和实仓进行测试，通过试验和对实验结果数据的处理分析，发现气密性不仅与环境密闭程度、结构材料及工艺质量有关，而且与测压上限及温度等环境条件有关；并且，在相同气密条件下，容器不同初始压力下的半衰期之间存在很好的线性相关性。

Glutin could accelerate the mice on the absorption of C. chinensis total alkaloids, to extend the elimination half-life, increase the blood concentration and bioavailability.

明胶可以加快小鼠对黄连总生物碱的吸收，延长消除半衰期，增加血药浓度和生物利用度。

But we don't care about Battlegrounds.

但我们并不在乎沙场中的显露。

Ah! don't mention it, the butcher's shop is a horror.

啊！不用提了。提到肉，真是糟透了。