首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   48篇
  免费   5篇
  2023年   1篇
  2022年   1篇
  2021年   1篇
  2020年   2篇
  2018年   5篇
  2017年   3篇
  2016年   3篇
  2015年   4篇
  2013年   12篇
  2012年   2篇
  2011年   2篇
  2010年   2篇
  2009年   2篇
  2008年   2篇
  2006年   1篇
  2003年   1篇
  1995年   2篇
  1994年   2篇
  1990年   1篇
  1989年   1篇
  1986年   1篇
  1978年   1篇
  1972年   1篇
排序方式: 共有53条查询结果,搜索用时 15 毫秒
31.
This article traces the beginnings of metallurgy in the eastern half of the African continent, focusing on three regions: (1) Egypt and Nubia; (2) the Great Lakes region of Central and East Africa; and (3) southern Africa. Metallurgy was not practiced much beyond the Nile valley until the first millennium BC, when copper, bronze and iron metallurgy began in Ethiopia and Eritrea, and iron metallurgy in the Great Lakes region. The expansion of agricultural societies carried iron metallurgy south, reaching its southern limit in South Africa by c. 300 cal AD. Copper was also smelted in southern Africa, but its use was restricted to pendants, bracelets, wire and other items of jewelry. In stark contrast to the metallurgical sequence in the Nile Valley, there was no production of tin, lead, gold or silver in central or southern Africa before these regions were linked to the Islamic world system after c. 800 AD.  相似文献   
32.
33.
34.
35.
36.
37.
38.
Many technologies have both vital legitimate uses and potent military applications. An international regulatory regime has been devised for the purpose of monitoring the use of the most dangerous of these technologies, namely chemical, biological and nuclear weapons. Multiple examples of the use of chemical and biological weapons against members of the public, and evidence of prohibited state weapons development programs, demonstrate the vital need for a more effective enforcement regime. The authors discuss the concept and threat of dual‐use technology, the existing regulatory regime and its shortcomings, and propose enhancing this regime with powerful international judicial authorities to enable the prosecution of any state, group or individual who attempts to misuse dual‐use technology.  相似文献   
39.
40.
The origins of the copper, tin and lead for China's rich Bronze Age cultures are a major topic in archaeological research, with significant contributions being made by archaeological fieldwork, archaeometallurgical investigations and geochemical considerations. Here, we investigate a recent claim that the greater part of the Shang‐period metalwork was made using metals from Africa, imported together with the necessary know‐how to produce tin bronze. A brief review of the current status of lead isotopic study on Shang‐period bronze artefacts is provided first, clarifying a few key issues involved in this discussion. It is then shown that there is no archaeological or isotopic basis for bulk metal transfer between Africa and China during the Shang period, and that the copper and lead in Shang bronze with a strongly radiogenic signature is not likely to be from Africa. We call for collaborative interdisciplinary research to address the vexing question of the Shang period's metal sources, focusing on smelting sites in geologically defined potential source regions and casting workshops identified at a number of Shang settlements.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号