全文获取类型
收费全文 | 6679篇 |
免费 | 259篇 |
出版年
2020年 | 70篇 |
2019年 | 105篇 |
2018年 | 164篇 |
2017年 | 153篇 |
2016年 | 226篇 |
2015年 | 135篇 |
2014年 | 137篇 |
2013年 | 1784篇 |
2012年 | 182篇 |
2011年 | 232篇 |
2010年 | 195篇 |
2009年 | 178篇 |
2008年 | 158篇 |
2007年 | 140篇 |
2006年 | 136篇 |
2005年 | 97篇 |
2004年 | 90篇 |
2003年 | 77篇 |
2002年 | 67篇 |
2001年 | 120篇 |
2000年 | 93篇 |
1999年 | 108篇 |
1998年 | 81篇 |
1997年 | 81篇 |
1996年 | 72篇 |
1995年 | 58篇 |
1994年 | 57篇 |
1993年 | 85篇 |
1992年 | 74篇 |
1991年 | 56篇 |
1990年 | 59篇 |
1989年 | 68篇 |
1988年 | 56篇 |
1987年 | 79篇 |
1986年 | 55篇 |
1985年 | 79篇 |
1984年 | 60篇 |
1983年 | 110篇 |
1982年 | 79篇 |
1981年 | 80篇 |
1980年 | 85篇 |
1979年 | 62篇 |
1978年 | 72篇 |
1977年 | 89篇 |
1976年 | 71篇 |
1975年 | 73篇 |
1974年 | 57篇 |
1973年 | 51篇 |
1972年 | 50篇 |
1971年 | 56篇 |
排序方式: 共有6938条查询结果,搜索用时 15 毫秒
41.
42.
Charcot-Marie-Tooth disease is a hereditary motor and sensory neuropathy first described in 1886. Our increasing knowledge of this disease correlates well with the development of methods used in neurology over the past 100 years. Although its physiopathology and treatment is still not fully understood, current developments in techniques are opening the way to future discoveries. We have divided its history into three theoretical periods: the first from 1886 to 1956, which was devoted to clinical and pathological study of the disease; the second from 1956 to 1982, which saw the development of electromyography in the investigation of neuromuscular diseases; and the last and current period based upon genetic research, using the methods of molecular biology. 相似文献
43.
ABSTRACT. We determine the location equilibria in a duopoly model under a novel solution concept. Typically, spatial equilibrium is described as either a simultaneous price and location game, or else as a two-stage location-then-price game. We introduce a new alternative, a two-stage price-then-location game. It is well known that no (pure strategy) equilibrium usually exists under the two standard solution concepts when products are homogeneous. We show this is also true for the new concept. We then provide numerical results for a specific functional form (the logit model) which introduces product heterogeneity into the standard framework, restoring equilibrium when the degree of substitutability between products is not too small. 相似文献
44.
James G. Strathman 《Journal of regional science》1992,32(4):501-509
ABSTRACT. This paper examines the impacts of JRS articles in the areas of theory, methods and empirical analysis, as represented by subsequent citations reported in the Social Sciences Citation Index. A model relating the mix of theoretical, methodological and empirical research published in the JRS to subsequent citations is estimated. The time distribution of theoretical and empirical citations also indicates that the knowledge diffusion process in these two areas may be segmented. 相似文献
45.
Günter Grönbold 《Indo-Iranian Journal》1992,35(4):273-297
Summary At the end of the second chapter of the Buddhist Klacakra-Tantra (dated c. 10th century) we find a group of verses in which several doctrines are characterized and criticized: Brahmanism, Vaisnavism, aivism, materialism, Islam and Jainism. Moreover the text refers to Buddhism itself as well as the so-called heterodox Buddhist schools. It is the only old Sanskrit text known until now in which the Islam is mentioned and recognized as a doctrine. 相似文献
46.
47.
This paper is concerned with the products of a number of Neolithic quarries in highland Britain. It investigates the claim that the scale of axe distribution was partly the result of social factors which resulted in these artefacts gaining an added value in areas remote from their sources. One case study considers the sequence of production in Cumbria, in relation to the tensile strength of the rock quarried in different parts of the region. It shows that these considerations had only a limited influence over the choice of stone source and the scale on which it was worked. A second study compares the tensile strength of the main raw materials used for making non-flint axes with the extent to which these sources were actually exploited. Again there is only a limited relationship between the two, suggesting that social factors may indeed have been important. 相似文献
48.
Carl G. Amrhein 《Geographical analysis》1986,18(1):1-18
A simulation model of a multiregional labor migration process is developed. Information about employment conditions in alternative regions is transmitted in a combination of three channels. The adopted emission policies directly control the amount of information available to potential migrants which, in turn, determines the potential migrant's perception of the level of welfare in the other regions. The effect of several different advertising policies on migration streams is examined. Employers can pursue a number of policies designed to maximize their return. Other agencies adopt policies that facilitate the matching process between unemployed workers and vacant jobs. Results are presented for a number of simulation experiments. 相似文献
49.
50.