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   5610篇
  免费   182篇
  2020年   61篇
  2019年   93篇
  2018年   114篇
  2017年   131篇
  2016年   164篇
  2015年   123篇
  2014年   116篇
  2013年   1769篇
  2012年   125篇
  2011年   154篇
  2010年   155篇
  2009年   131篇
  2008年   134篇
  2007年   100篇
  2006年   92篇
  2005年   81篇
  2004年   79篇
  2003年   56篇
  2002年   57篇
  2001年   83篇
  2000年   75篇
  1999年   75篇
  1998年   55篇
  1997年   62篇
  1996年   52篇
  1995年   46篇
  1994年   47篇
  1993年   59篇
  1992年   58篇
  1991年   47篇
  1990年   43篇
  1989年   53篇
  1988年   51篇
  1987年   65篇
  1986年   54篇
  1985年   71篇
  1984年   52篇
  1983年   95篇
  1982年   66篇
  1981年   67篇
  1980年   67篇
  1979年   59篇
  1978年   52篇
  1977年   70篇
  1976年   55篇
  1975年   55篇
  1974年   42篇
  1973年   38篇
  1972年   37篇
  1971年   40篇
排序方式: 共有5792条查询结果,搜索用时 31 毫秒
71.
The upper Mersey Valley was glaciated on three occasions during the Pleistocene. The youngest, Rowallan Claciation, probably commenced after 28000 years B.P. The maximum ice limit was attained before 13500 years B.P., and retreat occurred before 10000years B.P. Deposits associated with Rowallan Glaciation are weakly weathered chemically. They overlie moderately weathered deposits that were formed during the Arm Glaciation, which is inferred from relative dating data to have occurred before the Last Interglacial Stage. North of the deposits and ice limits of the Arm Glaciation extremely weathered tills and rhythmites occur. They were formed by ice of the Croesus Glaciation which is inferred to be of Early Pleistocene age or older.  相似文献   
72.
This paper considers the development of linked small-area spatial econometric models in which income flows between the areas constitute an important part of model specification. The attributes of income diffusion processes are considered in detail. Both static models and temporal income diffusion models are discussed. The spatial and spatial-temporal autocorrelation functions are derived which provide a measure of the spatial distribution of income. The Green function is also derived as a measure of income impulses through the system of regions. An important aspect of the paper is to relate properties of these functions to key economic parameters in particular propensities to spend locally and to spend nonlocally.  相似文献   
73.
74.
75.
76.
Lois Bryson and Faith Thompson, An Australian Newtown. Life and Leadership in a Working‐class Suburb, Penguin, Melbourne, 1972, pp. 380, $2.25. Bernard Barrett, The Inner Suburbs. The Evolution of an Industrial Era, Melbourne University Press, Melbourne, 1971, pp. 181 + xv, $9.00. Theo W. Brown with Keith Willey, Crown of Thorns. The Death of the Great Barrier Reef?, Angus and Robertson, Sydney, 1972, pp. 128 + xiii, $2.95.  相似文献   
77.
This paper is a statistical and geological study of the results of analysis of flint from British and West European flint mines, carried out by emission and atomic absorption spectroscopy. Groups of flint specimens were studied from each geographically separate flint mining area. Flints were analysed for a group of easily measured trace elements shown by previous work to be generally present. The ratios between the trace elements form a consistent pattern for each flint mine and statistically valid differences of pattern can be recognized between different flint mines. A geological investigation shows that the measured trace elements may be derived from clay minerals and explains geographical and statistical variation in the composition of flint in terms of its mode of origin in the chalk. An advanced statistical technique allows individual flint specimens of unknown origin to be attributed by their composition to one or other of the identified flint sources. The archaeological implications of this study are discussed.  相似文献   
78.
79.
80.
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