本底

The background survey and tracking survey of artificial reef area in Chenghai Laiwu were carried out before and after reefing in 2003 and 2007, respectively. The results indicated that after the deployment of artificial reefs, the biomass density of fishery resources increased by 25.63 times, which were much higher than before. The resources species was much more abundant; total number increased from 23 to 41, which increased by 0.78 times. The crab resources sharply increased by 1.75 times after artificial reef were deployed. Harpodon nehereus and Portunus sanguinolentus , which did not appeared in background survey, now became the dominant species in tracking survey. There were high diversity indexes in artificial reefs area and control area in tracking survey. In conclusion, the results indicated that the fish-aggregating effect of artificial reef site has improved a lot, and the community structure and the habitat environment have been significantly improved.

摘 要：2003和2007年分别对澄海莱芜人工鱼礁区进行了投礁前的本底调查和投礁后的跟踪调查，结果表明，投礁后礁区海域游泳生物的资源密度明显比投礁前高，增加了25.63倍；礁区海域各类资源种类均比投礁前丰富，总种数由投礁前的23种增加至41种，比投礁前增加了0.78倍，其中，蟹类种数增加最多，增加了1.75倍；在本底调查中没有出现的经济种类龙头鱼 Harpodon nehereus 和红星梭子蟹 Portunus sanguinolentus 在跟踪调查中已成为主要优势种；Shannon-Wienver多样性指数在礁区和对比区均比投礁前有所增加。

Based on the data of aerosol chemical compositions obtained at WMO GAW (World Meteorological Organization Global Atmospheric Watch) station in eastern China－Lin'An regional background air pollution monitoring station, two methods (referred as Malm method and Stelson method) that were described by Malm (Malm et al.,1994) and Stelson (Stelson and Seinfeld, 1981) were used to study the mass closure of sampled aerosols.

本文通过在WMO GAW 区域大气本底污染监测站－临安大气本底污染监测站采集的气溶胶样品的化学成分的分析结果，分别用Malm（1994）和Stelson（1981）提出的方法（分别记为Malm方法和Stelson方法）重建气溶胶质量浓度，并与称重获得的质量浓度进行对比，发现虽然Stelson和Malm方法所考虑的物质组成及所使用的化学成分个数并不相同，其计算结果略有差异，但总的来说两种方法都能较好的反映绝大部分的气溶胶质量，在实际应用中可以根据所分析的化学成分数据情况和研究的目的采用不同的质量重建方法。

Based on the data of aerosol chemical compositions obtained at WMO GAW (World Meteorological Organization Global Atmospheric Watch) station in eastern China-Lin' an regional background air pollution monitoring station, two methods (referred as Malm method and Stelson method) that were described by Malm and Stelson were used to study the mass closure of sampled aerosols.

通过在WMO GAW区域大气本底污染监测站－临安大气本底污染监测站采集的气溶胶样品的化学成分的分析结果，分别用Malm(1994)和Stelson(1981)提出的方法（分别记为Malm方法和Stelson方法）重建气溶胶质量浓度，并与称重获得的质量浓度进行对比，发现虽然Stelson方法和Malm方法所考虑的物质组成及所使用的化学成分个数并不相同，其计算结果略有差异，但总的来说2种方法都能较好的反映绝大部分的气溶胶质量，在实际应用中可以根据所分析的化学成分数据情况和研究的目的采用不同的质量重建方法。

Based on the data of aerosol chemical compositions obtained at WMO GAW(World Meteorological Organization Global Atmospheric Watch) station in eastern China——Lin'an regional background air pollution monitoring station,two methods(referred as Malm method and Stelson method) that were described by Malm and Stelson were used to study the mass closure of sampled aerosols.The inter-comparison of reconstructed aerosol masses with the gravimetric masses showed good agreements,although the tw...

通过在WMO GAW区域大气本底污染监测站——临安大气本底污染监测站采集的气溶胶样品的化学成分的分析结果，分别用Malm(1994)和Stelson(1981)提出的方法(分别记为Malm方法和Stelson方法)重建气溶胶质量浓度，并与称重获得的质量浓度进行对比，发现虽然Stelson方法和Malm方法所考虑的物质组成及所使用的化学成分个数并不相同，其计算结果略有差异，但总的来说2种方法都能较好的反映绝大部分的气溶胶质量，在实际应用中可以根据所分析的化学成分数据情况和研究的目的采用不同的质量重建方法。

Main contents and conclusions are: 1 The ionization current was measured continuously by a charge-integration method with a computer after the introduction of radon into the chamber.

主要内容及结论：1充氡后利用计算机连续进行电离电流累积测量，得到了精细的电流随时间的变化曲线，可清楚看出氡及其子体的生成衰变造成的电离电流的生长—稳定—衰减过程，与理论计算值进行了比较，由电离电流衰减速度的变化得出氡吸附作用的影响，并测量到电离室冲洗后氡的反扩散现象；2由已知活度的标准源定出相对测量的刻度系数K值，K=24.62 Bq／pA，对同一个监测源以半年为周期进行多次测量后得出稳定性符合要求；3通过测量电离电流和气压的关系曲线以及不同气压下的饱和曲线，确定了常规的工作条件；4测量了盐酸清洗电离室内表面降低本底的效果；5不确定度分析表明相对测氡的扩展不确定度(k=2)小于5％，由本底涨落得出探测下限为0.5 Bq；6理论上对壁损失修正进行了计算，实验上保持电离室工作在饱和区的情况下，测量了不同气压下电离电流的变化，从中得出了壁损失随气压变化的规律，可以看出，电离电流的实测值和计算值随气压变化规律基本一致；当气压大于125 kPa时，端效应等其它因素造成的影响不大于2％，因而在此工作条件下，测量电离电流后通过计算修正壁损失可以实现近似的绝对测氡，提出了进一步提高绝对测量准确度的方法。

A new method, by which we use single gas-flow multi-wire proportional counter for αβ simultaneous measurements, is recommended.

修正系数；标准源；低本底；本底计数率；同时测量；正比计数管；反符合电路；电荷灵敏放大器

This study investigated rangeland resource basal actuality.

本项研究旨在对天山北坡中段的草地资源本底现状做新的、深入地研究，为草地的综合开发与利用提供科学依据。

It was also proved that the tac promoter had high basal level expression.

本研究也再次验证了tac启动子有较高的本底表达。

So, the radiation backgrounds of DAMA set-up have been studied in the thesis, and the simulated values are in coincidence with the ones of DAMA experiments.

为此，我对DAMA实验的本底问题进行了模拟研究，在低能区获得了同DAMA实验本底计数相符的结果。

Base molecules can be labeled because of specific interactions between the fluorescent dye molecules and base molecules.

利用荧光染料分子与本底分子之间特定的相互作用可以对本底分子进行标记。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。