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   2559篇
  免费   143篇
  2023年   32篇
  2021年   10篇
  2020年   62篇
  2019年   69篇
  2018年   160篇
  2017年   123篇
  2016年   136篇
  2015年   100篇
  2014年   79篇
  2013年   785篇
  2012年   96篇
  2011年   91篇
  2010年   98篇
  2009年   83篇
  2008年   55篇
  2007年   94篇
  2006年   74篇
  2005年   25篇
  2004年   34篇
  2003年   27篇
  2002年   26篇
  2001年   27篇
  2000年   14篇
  1999年   23篇
  1998年   21篇
  1997年   11篇
  1996年   13篇
  1995年   27篇
  1994年   13篇
  1993年   11篇
  1992年   17篇
  1991年   11篇
  1990年   8篇
  1989年   12篇
  1988年   13篇
  1987年   17篇
  1986年   13篇
  1985年   16篇
  1984年   13篇
  1983年   12篇
  1982年   11篇
  1981年   12篇
  1980年   15篇
  1979年   9篇
  1978年   10篇
  1977年   7篇
  1976年   12篇
  1975年   9篇
  1972年   10篇
  1970年   9篇
排序方式: 共有2702条查询结果,搜索用时 15 毫秒
1.
This paper explores the role of Hispania in the Atlantic route in Roman times. We analyse the different Atlantic Iberian territories along this route, based on recent archaeological advances and discoveries related to trade as well as the shipping infrastructure. The aim is to explain the origin and evolution of a new maritime area that was completely integrated with the political and commercial structure of the Empire, with trade routes that followed the coastal areas of the Iberian Peninsula all the way to the Mediterranean.  相似文献   
2.
Palace lanterns were important and highly visible decorations in the imperial palace in Beijing, China, during the Qing dynasty (1636–1912). Most lanterns had colourful tassels made of fibres. The study performed a comprehensive investigation of the materials and dyes used for palace lantern tassels preserved in The Palace Museum, Beijing. Eight samples with different colours, including yellow, green and red, from five palace lanterns were analysed. By using ultra-performance liquid chromatography combined with time-of-flight mass spectrometry, the compositions of the dyes were identified quickly, and thus the dyes' origins were explored. A X-ray fluorescence spectrometer assisted in the detection of whether a mordant was used during the dyeing process. As a result, the tassels were all made of silk, discovered through the use of microscopic observation and micro-Fourier transform infrared spectrometry analysis. Different dyeing techniques were found in these tassels: yellow tassels were dyed by cork tree or turmeric by a direct dyeing method; greens were dyed by pagoda bud with an iron mordant, or by the combination of cork tree and indigo using multi-dyeing method; and red tassels were coloured with different acid red industrial dyes. These results provide valuable data for the conservation of ancient textile tassels and contribute to the investigation of other hanging tags.  相似文献   
3.
ABSTRACT. This paper examines the RAS, Mc Menamin and Haring, and Lagrange-multiplier update methods in the context of the dual accounting system of the rectangular input-output model. The motivation was to determine if the additional information contained in the dual system is exploitable, while maintaining the integrity of the rectangular structure with all its advantages. Tests were conducted on the performance of the various algorithms for a derivative Leontief model relative to their performance on the rectangular structure. The results obtained for rectangular tables were generally better than those obtained for the more conventional Leontief ones.  相似文献   
4.
5.
Results of a combined archaeological and analytical project of Late Neolithic/Early Bronze Age copper, bronze and lead artefacts from four distinct areas of mainland Greece are presented. The aim of the study is to understand better the stages of technological development of each region, their possible ore sources and also to assess any external contribution to or internal evolution of their metallurgy. Interesting results which could challenge the established view of Late Neolithic/Early Bronze Age metallurgy in the Greek mainland are presented.  相似文献   
6.
"This paper presents a two-sector dynamic model of regional population change. The model contains a migration equation, an earnings equation, and an amenity equation for each region. In the context of this model, migration is seen as a disequilibrium process through which the regional populations move towards equilibrium positions. Migration occurs when one region is perceived to be superior to the other on the basis of its earnings and amenity levels. Equilibrium is achieved when population movements between the regions eliminate any differences in their relative attractiveness. A comparative-static analysis of the model is presented to analyze the effects of policy changes and exogenous shocks on the distribution of population among the regions." The geographical focus is on the United States.  相似文献   
7.
8.
Aztecs: An Interpretation. By INGA CLENDINNEN. New York: Cambridge University Press, 1991. Pp. xiii, 398.

The Slippery Earth: Nahua‐christian Moral Dialogue in Sixteenth‐century Mexico. By LOUISE M. BURKHART. Tucson: The University of Arizona Press, 1989. Pp. xii, 242.  相似文献   

9.
10.
In the past decade Tobler has provided an innovative cartographic presentation of migration flows. The central theme of this research has been to utilize detailed migration data to reveal the underlying structures of migration flows. Even though the analyses are not explanatory models of migration exchanges, the application of these techniques to migration flows over time and across different spatial scales provides a visual generalization of often extremely complex flows. The application of his techniques at two spatial scales for the Netherlands illustrates both the strengths and weaknesses of migration force fields for the analysis of migration.  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