杭州湾中部实测波浪特性分析

利用杭州湾中部一年实测波浪资料,分析该地区的波参数统计变化特性,采用最小二乘法拟合得出相关参数之间的关系式,并统计分析了频谱特性。结果表明:杭州湾中部以小浪和轻浪为主,在各月分布较为均匀,年平均周期为2.97 s;最大一次波浪过程为冷空气影响所致,影响强度大于台风莫拉克;常浪向分布在东北至东南向,其中又以小浪出现较多,对应的波周期以2~4 s为主;强浪向主要分布在西北和东北方向,对应的波周期主要分布在3~5 s;多数特征波参数之间相关关系较好;由谱分析得知风浪占多数,且以单峰为主。研究结果可为相关工程和理论研究提供基础资料。     

PRELIMINARY STUDY ON THE FLOODING AND DROUGHT CLAMITY DURING PAST 1500 YEARS IN THE HAI′AN REGION，JIANGSU PROVINCE

Collection and arrangement of the historical records of climatic changes and environment evolution,espectial-lyin the aspect of calamities,are made on the history documents of past 1500 years about Haiˊan region,Jiangsu Province.There existed two obvious flooding-drought frequently-occurring periods:one was from 1550 AD to 1850 AD and another was 100 AD to 1200AD.The period of 1550 AD to1850 AD is interrupted by two relatively arid and cold climatic periods:one was from 1630 AD to 1700 AD and another was 1750 AD to 1820 AD.The main characteristic of the calamity periods is that they occurred by turns,and sometimes,both drought and flooding occurred in the same year.The instability of the climatic changes in the Little Ice Age may be the main reason of the frequently-occurring flooding and drought in Haiˊan region.Research results also show that the frequently-occurring periods of flooding and drought is in close relationship with the solar activity,and therefore,occurrence of the flooding and drought may be in relation with the intensity of the solar activity.This hypothesis may need further study in the future.     

上海天文台激光测距站的时频系统

本叙述了上海天台人卫激光测距站的时频系统。随着测距精度的提高，时频系统也要不断地加以改进，包括频率标准和时间同步技术。     

干旱威胁乌干达经济增长和渔业出口

近期,一场罕见的持续干旱袭击了乌干达,它导致乌境内各主要水电站水位均偏低,水电供应紧张。由于干旱与接踵而至的电力能源危机,该国本财政年度国家经济增长指数将可能受到影响。专家警告说,由于接二连三的恶劣天气条件,乌干达2005～2006财政年度的GDP增长率有可能将创下十几年     

Influence of Ultrasonic Treatment on the Allergenic Properties of Shrimp （Penaeus vannamei ） Allergen

The present study was undertaken to determine whether high intensity ultrasound could reduce the allergic properties of shrimp allergens. Reducing the allergenic properties of these allergens will be beneficial to allergic individuals. Samples of shrimp protein extract and shrimp muscle were treated by high-intensity ultrasound with water bathing at 0 ℃ or 50 ℃ for different time periods. The treated and untreated samples were then analyzed by SDS-PAGE, Western blots and competitive inhibition ELISA （Ci-ELISA） to determine the shrimp allergenicity. The results show that high-intensity ultrasound has no effect on allergenicity when the extracts were treated at 0℃. However, a significant decrease was observed in the level of the major shrimp allergen, Pen a 1, when the samples were treated at 50 ℃. In the determination of allergenicity with CiELISA, a reduction in IgE binding was also observed.     

流动VLBI站氢原子钟的研制与性能测试

氢脉泽是射电天文所必需的频率标准.文中对为流动vLBI站研制的新一代氢脉泽的物理结构特点进行了讨论，包括对腔泡结构、磁屏蔽、原子束光学系统等.同时性能测试表明在80秒到1天之间频率稳定度优于1×10     

BPM载频产生器的研制

介绍ＢＰＭ短波授时台新的载频产生器的设计与实现，该ＢＰＭ载频产生器以原子频标的５ＭＨｚ标频信号为参考，利用频率合成技术，产生出供发射机使用的２．５ＭＨｚ、５ＭＨｚ，１０ＭＨｚ、１５ＭＨｚ和２０ＭＨｚ五种高准确度的载频信号。这些信号既能单独输出，也可利用面板控制或遥控选择输出。为了保证系统的可靠性，采用了两冗余结构，并设置了必要的报警与指示。     

SOHM-4与MHM-2010氢原子频标的特点比较

基于对已投入国家授时中心守时运转的SOHM-4型与MHM-2010型氢原子频标的长期关注,对这两种氢原子频标的性能作了较详细的比较和分析。讨论了它们共同的优点、各自的特长和不足之处,还给出了稳定度的测试结果。