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   41356篇
  免费   1560篇
  42916篇
  2020年   522篇
  2019年   819篇
  2018年   922篇
  2017年   1127篇
  2016年   1222篇
  2015年   931篇
  2014年   905篇
  2013年   14062篇
  2012年   1042篇
  2011年   1072篇
  2010年   1072篇
  2009年   1068篇
  2008年   1010篇
  2007年   943篇
  2006年   836篇
  2005年   572篇
  2004年   571篇
  2003年   524篇
  2002年   504篇
  2001年   484篇
  2000年   432篇
  1999年   491篇
  1998年   452篇
  1997年   416篇
  1996年   398篇
  1995年   410篇
  1994年   354篇
  1993年   400篇
  1992年   381篇
  1991年   292篇
  1990年   284篇
  1989年   296篇
  1988年   298篇
  1987年   318篇
  1986年   291篇
  1985年   407篇
  1984年   439篇
  1983年   439篇
  1982年   382篇
  1981年   374篇
  1980年   416篇
  1979年   406篇
  1978年   395篇
  1977年   420篇
  1976年   375篇
  1975年   380篇
  1974年   283篇
  1973年   262篇
  1972年   240篇
  1970年   219篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
Pompeiian-style (hourglass) grain mills are common at many Roman sites within the circum-Mediterranean countries. Three examples are known from Corfe Mullen, London and Hamworthy in southern Britain. Petrographic examination, chemical and microprobe analyses indicate that the Corfe Mullen millstone and the London donkey mill were imported from central France into southern Britain. The Hamworthy mill should be designated a ‘flat donkey mill’, and represents a recent (post-Roman) import from a volcanic source in Sardinia. There is no evidence of importation of Roman donkey mills from Germany or for transportation of such mills (or stylistic derivatives) north of London.  相似文献   
72.
73.
This article reports a generalised and systematic approach to the thermoluminescence (TL) dating of samples which suffer from anomalous fading. We hypothesise that the TL signal from each mineral phase is composed of a stable and an unstable portion. The decay of the unstable TL is accelerated thermally, until only stable TL remains. The dating is then carried out on this stable signal. The results, on four known-age, coeval samples, exhibiting gross anomalous fading (25-50% loss over a few days), indicate that many, if not all, samples may successfully be dated with this approach.  相似文献   
74.
75.
WORDSWORTH and LAKE DISTRICT TOURISM: ROMANTIC RESHAPING OF LANDSCAPE   总被引:1,自引:0,他引:1  
Creative literature colours popular perception of landscape and place. An analysis of English romanticism, Wordsworth's poetry in particular, illustrates how the transformation of an actual landscape into a literary landscape helped change attitudes toward wilderness and natural beauty. The romantic ideology fostered impressions of an idyllic, untamed eden. In response to public fascination with this mythologized and emotional portrait of place, a tourist landscape emerged. Thus even those unfamiliar with romantic literature are encouraged to see particular landscapes from a literary perspective.
Dans la formation d'une perception envers un paysage ou un endroit, un élément important est souvent la littérature imaginaire. Une analyse du romantisme anglais, en particulier la poésie de Wordsworth, démontre comment la transformation d'un paysage actuel sous une forme littéraire contribua fortement à un changement d'attitude envers la nature. Cette idéologie romantique encouragea la notion d'un jardin d'Eden encore sau-vage. la fascination entretenue par ce portrait mythique créa finalement un environnement touristique. Même ceux qui n'ont guère connaissance en littérature romantique ont une vision d'un paysage particulier qui dérive dune perception littéraire.  相似文献   
76.
77.
ABSTRACT. The distribution of above-median income groups can be described accurately by OLS regression of the Pareto distribution. The excellent fit of log-linear regression has led some researchers to conclude that extrapolated income measures in the open end of the distribution are reliable. The analysis of income distribution data for metropolitan areas reveals: (1) that OLS tends to consistently overestimate the number of families in the tail, and (2) that the overestimation can have serious implications for hypothesis testing.  相似文献   
78.
ABSTRACT This paper investigates the implication of production-technology uncertainty for the exclusion theorem. The paper presents the result that the risk-averse firm facing production technology uncertainty prefers an intermediate location to avoid risk under certain conditions. The firm chooses an intermediate location (over a corner location) particularly if its degree of risk aversion overwhelms the inherent convexity of profit with respect to location. The latter depends, in turn, on the structure of production technology characterized by the elasticity of substitution and returns to scale parameters.  相似文献   
79.
ABSTRACT. This paper incorporates an exogenous taxing and service-providing public sector into a dynamic residential land-use model in order to examine how local-government fiscal policies alter the pace and pattern of residential development. The model is used to derive the comparative-dynamic responses to variations in the income, sales, and property taxes and public-service time paths. The results show how tax and expenditure effects systematically depend upon the anticipated relative growth rates in rents to alternative uses and vary across locations within a given urban area as well as across urban areas themselves.  相似文献   
80.
ABSTRACT. This paper introduces the household interactive variable input-output (HIVIO) model to measure the effect of cost variation on industrial outputs. The model produces a variety of cost elasticities that separate out impacts on industrial prices, imports, and outputs, with “own” and “cross” elasticity components. Like the conventional input-output multipliers, these cost elasticities can be useful parameters to evaluate the substituting behavior of firms and consumers. By using the 1980 Korean input-output transactions table, we find the wage and import price effects on industrial prices, outputs, and import demands.  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