The melatonin rhythm: both a clock and a calendar

The paper briefly reviews the data which shows that the circadian production and secretion of melatonin by the pineal gland can impart both daily, i.e., clock, and seasonal, i.e., calendar, information to the organism. The paper summarizes the 3 patterns of nocturnal melatonin production that have been described. Clearly, regardless of the pattern of nocturnal melatonin production a particular species normally displays, the duration of nightime elevated melatonin is proportional to the duration of the night length. Since daylength under natural conditions changes daily the melatonin rhythm, which adjusts to the photoperiod sends time of year information to the organism. The melatonin receptors which subserve the clock message sent by the pineal gland in the form of a melatonin cycle may reside in the biological clock itself, namely, the suprachiasmatic nuclei (SCN). The melatonin receptors that mediate seasonal changes in reproductive physiology are presumably those that are located on the pars tuberalis cells of the anterior pituitary gland. Besides these receptors which likely mediate clock and calendar information, melatonin receptors have been described in other organs. Interestingly, the distribution of melatonin receptors is highly species-specific. Whereas the clock and calendar information that the melatonin cycle imparts to the organism relies on cell membrane receptors, a fact that is of some interest considering the high lipophilicity of melatonin, recent studies indicate that other functions of melatonin may require no receptor whatsoever.     

广西玉林市黑斑蛙春季感染曼氏迭宫绦虫裂头蚴情况调查

对玉林市黑宽蛙春季感染曼氏迭宫绦虫裂头蚴情况进行了调查，结果是：总感染率达71．4％，阳性蛙平均感染虫体数为5．8条，以25．1-35克这一重量段感染率为最高，达84．62％，雌性感染率略高于雄性。     

人工干预压采条件下东风湖泉域地下水环境响应研究

为掌握我国北方典型岩溶泉域在人工干预条件下地下水的动态响应规律,以涉县东风湖泉域为研究对象,结合区内地质、水文地质、2011-2021年地下水位动态监测和地下水压采资料,在分析该地区地下水动态变化特征的基础上,运用GMS软件构建了在人工压采干预作用下的地下水流数值模拟模型,对地下水位变化趋势进行了预测。结果表明：①研究区地下水动态变化明显,具有周期性、滞后性,具体表现为4个变化阶段;②研究区内岩溶地下水整体呈现回升的状态,但是空间分布特征不同,上升区主要分布于下游地区;;③地下水类型为降水入渗-开采型,低水位期基本在5-6月,高水位期在1-2月;④在干预条件下,区内地下水位有着不同程度的回升,南部(下游)浅层水位响应特征值超过15m,中游地下水位响应特征值达到了5-10m,北部(上游)地下水位响应特征值为3-5m;上游和中游地下水位影响整体小于下游,下游水位响应尤为突出。该研究对于泉域内泉的保护以及地下水开发利用和保护具有重要的理论和实际意义。     

Leakage of mantle helium from the Liaodong Peninsula, China

The isotopic cumpositions of helium have been investigated in hot spring gases sampled from the Liaodong Peninsula. China. The³He/⁴He ratios range from 0.14 Ra (0.14 times the atmospheric³He/⁴He ratio of 1.40 × 10^-6 to 0.72 Ra.³He/⁴He versus⁴He/²⁰Ne ratios and He contents suggest that a small amount of mantle-derived helium reaches the earth’s surface. Helium iwtope ratios of the hot spring gases show a distribution pattern similar to the regional heat flow values, indicating that the positive thermal anomaly occurring in the rtrea is closely associated with the presence of mantle-derived helium. The observations described above provide some significant evidence that the molten magma originating from partial melting of the upper mantle may have intruded into the continental crust along the activity fault. The coupling of the presence of mantle He and heat flow anomalies to seismic activity in studied region seem to imply that there is an internal relationship between mantle degassing and seismic activity.     

我国优秀女排运动员弹跳力发展及其训练的分析研究

本文通过对我国优秀女排运动员及其后备人材不同年龄阶段弹跳力素质发展的分析研究,探讨女排运动员弹跳力素质发展变化的规律,及其不同年龄阶段主要训练手段的选择．为女排运动员科学选材、科学训练、制定多年训练计划等方面提供理论依据．     

单片机系统中的实时日历时钟

本文详细讨论了美国ＤＡＬＬＡＳ半导体公司新近生产的实时日历时钟芯片ＤＳ１２８８７在单片机应用系统中的使用方法,包括与８０５１单片机的硬件接口电路、编程和使用注意事项．     

喜树的种子休眠及更新

对喜树种子的休眠与更新进行了研究．结果表明,喜树种子成熟后有约４个月的休眠期．种子内部生物钟节律与所处环境的气候年变化节律相似,使种子处于周期性休眠状态．喜树种子的天然寿命约２年．大树和中树种子的天然更新能力优于小树和枯梢树．天然环境通过抑制已萌发种子的成苗和幼苗的生长发育而限制喜树利用种子进行自然更新,适当的人为干扰可大大促进自然更新．     

青海高原春小麦籽粒蛋白质积累规律研究

分析了阿勃,青春５３３,青农４６９、青农４５２等四个春小麦品种（品系）在青海西宁地区籽粒蛋白质相对含量的变化规律和蛋白质绝对含量的积累进程,结果表明,从开花至成熟,籽粒蛋白质相对含量的变化呈“Ｕ”型曲线,并以花后籽粒发育初期含量最花,花后３１天左右是该地区春小麦籽粒中蛋白质相对含量最低的时期。不同品种在花后不同时期蛋白质相对含量各不相同;籽粒蛋白质绝对含量的积累过程呈“Ｓ”形曲线,可用概率转换方程     

论温泉旅游的创新开发

近年来，温泉旅游发展迅速，但温泉旅游开发模式和活动项目的雷同化现象十分严重，从社会需求、温泉产品形象、温泉设计理念、温泉经营管理等方面都要求对温泉进行创新开发，温泉旅游开发的创新途径是主题创新、表现形式创新、内容创新和管理创新，只有这样温泉旅游才能可持续发展。     

SDH网的定时结构设计

传输网络定时是SDH网同步设计中的一个重要层面.首先介绍了定时保护倒换规则,然后分析了在设计过程中可能遇到的由于时钟倒换快慢引起的假定时环路问题,提出了科学规划的解决方法,最后得出了简单易行的传输网络定时环状结构.该结构解决了假定时环路问题,可应用于工程实际.