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   7828篇
  免费   435篇
  2023年   53篇
  2020年   136篇
  2019年   203篇
  2018年   298篇
  2017年   262篇
  2016年   332篇
  2015年   216篇
  2014年   205篇
  2013年   2067篇
  2012年   242篇
  2011年   265篇
  2010年   251篇
  2009年   244篇
  2008年   209篇
  2007年   212篇
  2006年   176篇
  2005年   116篇
  2004年   105篇
  2003年   102篇
  2002年   120篇
  2001年   148篇
  2000年   108篇
  1999年   117篇
  1998年   92篇
  1997年   83篇
  1996年   92篇
  1995年   73篇
  1994年   61篇
  1993年   75篇
  1992年   72篇
  1991年   61篇
  1990年   60篇
  1989年   56篇
  1988年   53篇
  1987年   62篇
  1986年   61篇
  1985年   69篇
  1984年   80篇
  1983年   85篇
  1982年   68篇
  1981年   67篇
  1980年   66篇
  1979年   62篇
  1978年   67篇
  1977年   68篇
  1976年   61篇
  1975年   71篇
  1974年   42篇
  1973年   38篇
  1972年   41篇
排序方式: 共有8263条查询结果,搜索用时 31 毫秒
111.
112.
113.
In this paper, I investigate some of the causes of city formation in spatial economies. A model is proposed in which an intermediate differentiated input shared by more than one industry is the cause of the formation of diversified cities. The desire of both the traded-good and the local-good industries to employ a variety of inputs from the intermediate industry provides the reason for the agglomeration of the three industries. In addition, the paper contains a comparative-statics analysis of the model in an open and a closed-city framework. It is demonstrated that the larger the city, the more variety of intermediate inputs the city can provide and the more specialized it is in the production of the traded-good. Moreover, the model suggests that different industrial structures will result in different city Sizes.  相似文献   
114.
115.
116.
117.
118.
The chemical and mineralogical characterization of seven ceramic fragments produced within Tiwanaku state (c.500–1000 ce ) is reported. The instrumental techniques used included X‐ray elemental and mineralogical chemical analysis, Raman spectroscopy, and scanning and light microscopy. The results indicate there are several clay types, although they show similarities, such as the use of a plant‐based temper. The red colour of the decoration is hematite, and manganese oxides such as jacobsite are present in the black. The white colour is a mixture of gypsum and clay, and the orange is a mixture of hematite and clay. The use of colours, the quality of the clays and the temperatures reached during pottery firing point to expertise in ceramic production and to complex decision‐making processes. The multi‐elemental archaeometric approach documented here could become an important tool to shed a light on ancient ceramic technology and the internal variance of Tiwanaku pottery.  相似文献   
119.
The reasons why the Western Mediterranean, especially Carthage and Rome, resisted monetization relative to the Eastern Mediterranean are still unclear. We address this question by combining lead (Pb) and silver (Ag) isotope abundances in silver coinage from the Aegean, Magna Graecia, Carthage and Roman Republic. The clear relationships observed between 109Ag/107Ag and 208Pb/206Pb reflect the mixing of silver ores or silver objects with Pb metal used for cupellation. The combined analysis of Ag and Pb isotopes reveals important information about the technology of smelting. The Greek world extracted Ag and Pb from associated ores, whereas, on the Iberian Peninsula, Carthaginians and Republican‐era Romans applied Phoenician cupellation techniques and added exotic Pb to Pb‐poor Ag ores. Massive Ag recupellation is observed in Rome during the Second Punic War. After defeating the Carthaginians and the Macedonians in the late second century bce , the Romans brought together the efficient, millennium‐old techniques of silver extraction of the Phoenicians, who considered this metal a simple commodity, with the monetization of the economy introduced by the Greeks.  相似文献   
120.
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