BIOCHEMICAL CHANGES DURING DEVELOPMENT OF EGGS AND YOLK-SAC LARVAE OF HERRING AND PLAICE

Changes in quantities of water, sodium, potassium, lipid and protein were compared in developing eggs and yolk-sac larvae of herring dupes harengus L., a species with demersal eggs, and plaice Pleuroncctcs platessa L., a species with pelagic eggs. The principal difference between the two species was the occurrence in herring, but not in plaice of considerable increases in water content and in one or both of the above ions at three distinct stages: at fertilization,during the middle stage of egg development, and in the days immediately after hatching. Newly hatched larvae of the two species differed greatly in water content because of the difference in mass and water content of the yolk, not in the water content of the rest of the body. In herring, there were increases in sodium and potassium which coincided broadly with the increase in water content. These differences are related to the gradual acquisition of buoyancy by herring during this period, comparable with the buoyancy conferred on plaice eggs a     

旅游区域研究方法

一.平均中心 1.概述平均中心可由一组特定的数据确定,也可由几组不同的数据来确定,然后进行比较。例如,确定某一景点在有代表意义的某一天每一小时的游客分布平均中心,可能揭示出这些游客行为的有价值的信息。平均中心也可以通过比较不同的旅游设施——饭店、汽车旅馆、餐厅、旅行社等——的相对位置而在图上求出。这样,通过这些综合信息,就可以更好地理解影响各类旅游业务的区位与经营状态的作用力。     

元素迁移的分维结构,级序路径及共轭地球化学异常存在的理论依据

微量元素在矿源岩中迁移遵循严格的级序路径，并且存在两种迁移倾向。迁移的结果图象是一分维结构，两种共轭地球化学异常出现的有利环境是温度高度反差地区和大断裂系及其其附近。     

流体包裹体的挥发组分——黑色页岩中石英脉型金矿床的勘查标志

本文对英国北威尔士多尔盖莱金矿带石英脉中的流体包裹体进行了研究,结果表明,流体包裹体中的挥发组分可用来区分含金流体和不含金流体,从而可作为黑色页岩中石英脉型金矿床的勘查标志。     

环北太平洋构造地层地体图

新近编制的一幅五百万分之一的环北太平洋构造地层地体图首次详尽描述了该区的地质与大地构造。该图的近岸部分表示了前苏联远东、阿拉斯加、加拿大科迪勒拉及其与美国西北部交界处的主要地体、地缝合线、年轻的叠加组合及继生盆地。该图的远岸部分表述鄂霍茨克海、太平洋、白令海及北冰洋区的大洋板块、洋中脊、俯冲带、主要中洋脊磁