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   3850篇
  免费   153篇
  2020年   61篇
  2019年   68篇
  2018年   104篇
  2017年   101篇
  2016年   127篇
  2015年   90篇
  2014年   83篇
  2013年   1182篇
  2012年   94篇
  2011年   102篇
  2010年   97篇
  2009年   89篇
  2008年   96篇
  2007年   81篇
  2006年   67篇
  2005年   63篇
  2004年   55篇
  2003年   40篇
  2002年   56篇
  2001年   59篇
  2000年   32篇
  1999年   52篇
  1998年   24篇
  1997年   34篇
  1996年   27篇
  1995年   23篇
  1994年   39篇
  1993年   33篇
  1992年   35篇
  1990年   32篇
  1989年   29篇
  1988年   32篇
  1987年   33篇
  1986年   32篇
  1985年   36篇
  1984年   52篇
  1983年   55篇
  1982年   48篇
  1981年   39篇
  1980年   34篇
  1979年   42篇
  1978年   42篇
  1977年   32篇
  1976年   32篇
  1975年   35篇
  1973年   28篇
  1972年   35篇
  1971年   21篇
  1970年   32篇
  1969年   21篇
排序方式: 共有4003条查询结果,搜索用时 31 毫秒
91.
By 1980, the Brasilian steel industry had grown to be the eighth largest among the market economies. It is a largely state-owned industry, much of the expansion of which has been funded by international capital. The pattern of development has not been externally imposed, however, but rather reflects the changing balance of class forces within Brasil as policies oscillate between nationalist, populist limits on foreign investment and open, pro-development strategies that rely on foreign investment. Both policies develop their own contradictions, that are reflected in frequent military interventions.  相似文献   
92.
"A classic case where out-migration interacted with many other geographical phenomena is provided by rural Ireland in the nineteenth century. The apparent turning point was the Great Famine of the 1840s, but the areas with the greatest suffering from starvation did not necessarily show the greatest population decline, suggesting that other forces were active. Considerable economic and social changes were already taking place before the Famine: fertility was being reduced, later marriage was becoming established and considerable emigration was already taking place. Immediately after the Famine those areas which had been hardest hit often reverted to pre-Famine conditions and did not show strong population decline until the 1870s. The Famine was a most serious event, but the modernization of Irish rural life, which linked emigration with changes in family structure, agriculture and population numbers, was more important in bringing about geographical change."  相似文献   
93.
94.
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   
95.
96.
"The spread of HIV-1 in the United Kingdom is simulated by a model which integrates behavioural and epidemiological processes within a multi-regional population projection framework and represents the spatial heterogeneities in the distribution of HIV which have significant effects on transmission patterns. Analyses determine the significance of different parameters in contributing to prediction uncertainty and highlight the importance of behavioural change and international population movements."  相似文献   
97.
Current federal hazardous and low-level radioactive waste management policies (under conjoint federalism) fail to balance national concerns for consistency with state concerns for equity, discretion, and adequate resources. Congress should expand conjoint federalism to permit states to charge differential fees on imported hazardous waste as it does for low-level radioactive waste. For low-level radioactive waste, clarification of the "take title" issue makes the present framework for state discretion implementable, given sufficient time.  相似文献   
98.
99.
100.
The paper examines the ancestry of Europeans in Sydney and that of the two largest non European groups. Spatial divergence occurs between the English, Scottish and Irish, and divergence from those of Australian ancestry. Residential persistence across generations occurs with persons of Greek, Italian, Maltese and Dutch origins, but not spatial segmentation. While there is greater language persistence in Greek and Italian second and third settlement concentrations, few third generation persons speak their ancestral language at home. The Chinese and Lebanese are compared with Greek and Italian ancestry in their areas of strongest representation. First generation Chinese are evident in areas of both low and high socioeconomic status, but without third generation language persistence. An evolving ethnic mix in Sydney is indicated.  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