Investigations in the U.S.S.R. of non-linear phenomena in the ionosphere

Investigations of non-linear ionospheric phenomena in the U.S.S.R. are reviewed. The facilities available and some non-linear phenomena first observed with these facilities are described. Among these are strong heating and non-linear absorption in lower parts of the ionosphere, self-modulation caused by intense Langmuir oscillations, the modulation of the auroral electrojet at VLF, stimulated ionization in the F-region, self-focusing effects at oblique incidence as well as many theoretical investigations of non-linear phenomena.     

Greek sightseers in the fayum in the third century B.C.

An attempt is made to determine the context and scope of Thuc. 11,45,2 on the assumption that the addressees are widows specifically. Current interpretations of the meaning of the passage and the connection between the two parts of the exhortation are criticized and modified. The message of Pericles is seen in the light of other funeral orations and placed within the perspective of widowhood in Athenian society.     

美国城市旅游

美国城市旅游对我国发展都市旅游有借鉴意义。本介绍了美国在散客旅游方式、旅游交通、城市旅游资源开发、旅游宣传资料以及旅馆业经营方式方面的一些做法。     

Laying the Foundation of U.S. Power in the Pacific

Book reviewed in this article:
David M. Pletcher, The Diplomacy of Involvement: American Economic Expansion across the Pacific, 1784–1900     

建国初期的冀朝鼎

新中国诞生后,百废待兴。冀朝鼎在帝国主义实施禁运和经济封锁的困难面前,积极探索中国外经贸的新体制,加强外汇管理,以灵活的外交,与11个国家签定了外贸协定,还成功地与日本、英国等未建交国家进行“民间贸易”．打破西方列强的孤立政策．开创了中国对外交往与贸易的新局面。     

伊格尔斯在《二十世纪的历史学》中对后现代史学理论的认知

近一百多年以来,各个学科包括历史学都发生了巨大变化,历史学家伊格尔斯的《二十世纪的历史学——从科学的客观性到后现代的挑战》＾①一书就是对史学思想变化的叙述和分析。