全文获取类型
收费全文 | 1856篇 |
免费 | 79篇 |
出版年
2023年 | 8篇 |
2020年 | 26篇 |
2019年 | 44篇 |
2018年 | 53篇 |
2017年 | 72篇 |
2016年 | 78篇 |
2015年 | 43篇 |
2014年 | 45篇 |
2013年 | 520篇 |
2012年 | 49篇 |
2011年 | 55篇 |
2010年 | 53篇 |
2009年 | 55篇 |
2008年 | 49篇 |
2007年 | 28篇 |
2006年 | 37篇 |
2005年 | 40篇 |
2004年 | 37篇 |
2003年 | 38篇 |
2002年 | 34篇 |
2001年 | 31篇 |
2000年 | 29篇 |
1999年 | 18篇 |
1998年 | 31篇 |
1997年 | 27篇 |
1996年 | 19篇 |
1995年 | 16篇 |
1994年 | 23篇 |
1993年 | 17篇 |
1992年 | 13篇 |
1991年 | 15篇 |
1990年 | 15篇 |
1988年 | 12篇 |
1987年 | 18篇 |
1986年 | 19篇 |
1985年 | 21篇 |
1984年 | 25篇 |
1983年 | 21篇 |
1982年 | 24篇 |
1981年 | 11篇 |
1980年 | 15篇 |
1979年 | 17篇 |
1978年 | 8篇 |
1977年 | 21篇 |
1976年 | 15篇 |
1975年 | 13篇 |
1974年 | 13篇 |
1973年 | 8篇 |
1972年 | 9篇 |
1968年 | 7篇 |
排序方式: 共有1935条查询结果,搜索用时 15 毫秒
1.
2.
3.
Jennifer G. Kahn John Sinton Peter R. Mills Steven P. Lundblad 《Journal of archaeological science》2013,40(2):1194-1202
We apply X-ray fluorescence (XRF) geochemical analysis to a collection of 'Opunohu Valley lithic artifacts from Mo'orea island to investigate the local scale of raw material procurement, adze production, use, and exchange within the Society Island archipelago. We use these data to document the distribution of non-local versus local volcanic artifacts in 'Opunohu Valley house sites, ritual sites, and specialized sites, as a means for establishing intra-site production and consumption patterns, and access to exotic, possibly superior, stone resources, and how these two themes correlate with site function or household wealth and status. Overall, 30% of the artifacts analyzed via WDXRF derive from non-local sources, notably two other islands in the archipelago outside of the political boundaries of Moorean chiefdoms. Our case study thus provides the first direct material evidence of intra-archipelago trade and exchange in the Society Islands. Intra-archipelago trade in adzes was certainly in place by as early as A.D. 1350, if not earlier, and continued up until the time of European contact. In addition, our analyses have identified a local adze production locale in the Afareaitu district of Mo'orea island. The patterns of local versus non-local adze production and exchange strongly suggest that dual interaction spheres were involved. The correlation between adzes and adze-related debris produced from off-island sources and sites with specialized use, which were often reserved for the social, ritual, and political elites in Ma'ohi society suggests that some of the exotic adzes derived from gift exchange between Mo'orea and ruling elites in Tahiti and the Leeward Islands. These adzes from afar would have solidified socio-political and ideological alliances between elites in the Windward and Leeward sectors of the archipelago. 相似文献
4.
ABSTRACT. In this paper the impact of spatial and nonspatial variables on the innovation potential and innovativeness of (small) industrial firms in The Netherlands will be analyzed. Innovation potential and innovativeness will be conceived as latent variables which will be measured by a partial least squares approach. The variables reflecting innovation potential are notably input variables such as internal and external R&D, while innovativeness will be based on output indicators such as the number of product and process innovations. The regional dimension enters our analysis essentially at two levels. First, we will investigate whether more innovative firms are to some extent spatially biased (i.e., on the basis of intrafirm characteristics). Secondly, we will analyze the relevance of an indigenous regional impact, per se. In other words, we will examine whether firms with an equal innovation capacity will differ in actual (i.e., realized) innovativeness as a consequence of different regional conditions. For the first issue, our results indicate that not all regions are equally well-endowed with potentially innovative (small) firms. Our analysis even demonstrates that these firms are underrepresented in regions which are generally considered to offer the most favorable production environment. After compensating for these differences in the composition of the regional set of firms, we demonstrate that an indigenous regional impact per se cannot be identified in The Netherlands. 相似文献
5.
6.
The technology of Roman harbours 总被引:2,自引:0,他引:2
John Peter Oleson 《International Journal of Nautical Archaeology》1988,17(2):147-157
7.
8.
Development of more sophisticated techniques for modeling longitudinal data has implications for improving our understanding of migration. This paper uses longitudinal data from the British Social Change and Economic Life initiative to disentangle the effects of population heterogeneity, progress through the life cycle and secular change on observed migration differentials. The data consist of retrospective life histories from people sampled in several contrasting localities in Great Britain, in which residential moves can be linked to changes in occupation and household structure. We present a framework for analysis of data of this type using a generalized linear modeling approach, together with results concerning variations in the probability of migration with age, gender, and changes in household and occupational circumstances. Of particular note is the evidence of substantial duration-of-residence effects and an unexpected later-career increase in migration propensity. 相似文献
9.
This paper will provide an introduction to a new field of research, viz. the sensitivity of the solution trajectory of a dynamic logit model (belonging to the class of discrete choice models) in the light of a multiperiod lag structure. It is well known from recent advances in the area of chaos and turbulence theory that the stability of a dynamic system is critically dependent on various factors, such as threshold values of parameters, initial conditions, and also the lag structure. This paper aims to identify the consequences of different lag structures in dynamic logit models (including also dynamic spatial interaction models). Various simulation experiments will be used to show that the onset of instability of the solution trajectory tends to decrease as the number of time lags increases (depending also on the growth rate of the system). 相似文献
10.