全文获取类型
收费全文 | 4768篇 |
免费 | 204篇 |
出版年
2020年 | 71篇 |
2019年 | 90篇 |
2018年 | 123篇 |
2017年 | 134篇 |
2016年 | 155篇 |
2015年 | 113篇 |
2014年 | 115篇 |
2013年 | 1426篇 |
2012年 | 141篇 |
2011年 | 170篇 |
2010年 | 164篇 |
2009年 | 131篇 |
2008年 | 107篇 |
2007年 | 111篇 |
2006年 | 117篇 |
2005年 | 70篇 |
2004年 | 55篇 |
2003年 | 63篇 |
2002年 | 66篇 |
2001年 | 72篇 |
2000年 | 65篇 |
1999年 | 78篇 |
1998年 | 56篇 |
1997年 | 47篇 |
1996年 | 33篇 |
1995年 | 51篇 |
1994年 | 33篇 |
1993年 | 46篇 |
1992年 | 29篇 |
1991年 | 39篇 |
1990年 | 45篇 |
1989年 | 43篇 |
1988年 | 30篇 |
1987年 | 46篇 |
1986年 | 48篇 |
1985年 | 50篇 |
1984年 | 55篇 |
1983年 | 52篇 |
1982年 | 45篇 |
1981年 | 49篇 |
1980年 | 51篇 |
1979年 | 44篇 |
1978年 | 39篇 |
1977年 | 44篇 |
1976年 | 31篇 |
1975年 | 30篇 |
1974年 | 27篇 |
1973年 | 31篇 |
1972年 | 30篇 |
1970年 | 32篇 |
排序方式: 共有4972条查询结果,搜索用时 15 毫秒
991.
ABSTRACT. In problems of spatial choice, the choice set is typically more aggregated than the one considered by decision-makers, often because choice data are available only at the aggregate level. These aggregate choice units will exhibit heterogeneity in utility and in size. To be consistent with utility maximization, a choice model must estimate choice probabilities on the basis of the maximum utility within heterogeneous aggregates. The ordinary multinomial logit model applied to aggregate choice units fails this criterion as it is estimated on the basis of average utility. In this paper, we derive and discuss a model which utilizes the theory underlying the nested logit model to estimate the appropriate maximum utilities of aggregates. We also demonstrate that the aggregate alternative error terms are asymptotically Gumbel, thereby relaxing the assumption of extreme value distributed error terms. This is accomplished with help from the asymptotic theory of extremes. 相似文献
992.
993.
S. BLAU 《Arabian Archaeology and Epigraphy》1996,7(2):143-176
This paper reviews attempts by osteologists to identify activities in the past through examination of particular alterations to skeletal remains. Following an outline of the history of interest in occupational pathology, the physiology of bone is briefly summarised in order better to understand the potential of investigating occupation in the past. A history of archaeological research and interpretations in this field is then provided, followed by a discussion of a particular case study in which the human skeletal remains and material culture from the site of Tell Abraq were examined by the author in an attempt to identify bone alterations which may be attributed to certain activities. 相似文献
994.
Karl S. Kropf 《European Planning Studies》1996,4(6):717-737
The paper describes an approach to development control taken in France, bringing together the zoning system of planning and geographical and architectural studies of urban form. The approach addresses a number of issues, in particular the maintenance of the historical and regional character of towns, often eroded under systems of land‐use zoning. The principles and methods of the approach are set out and its application is illustrated by an example, illuminating both the approach and the context in which it was realized. 相似文献
995.
Ian D. Lunt 《Geographical Research》1997,35(3):342-348
Tree densities in the mid 1800s were calculated for 16 areas on the lowland Gippsland plain, Victoria, using data on historical maps. The plotless, closest individual method was used on map data, which listed the distance and compass bearings of trees from allotment corners. Densities ranged from 2 to 59 trees per hectare, with most estimates below 30 trees per hectare. Sparsest trees were in and near areas mapped as ‘open plains’ and the densest tree cover was on seasonally flooded river flats. Whilst it seems prudent to treat such figures as indicative rather than precise, this simple method holds considerable promise for obtaining quantitative estimates of tree densities before widespread clearing. 相似文献
996.
Archaeological artefacts identified as jet are often assumed to have originated from the principal British source, which is at Whitby in Yorkshire. Geological samples of jet have also been found within the Kimmeridge Blackstone in Dorset—a seam of oil shale which has been worked since prehistoric times to produce artefacts similar to those made from jet. This paper discusses the geology and geochemistry of jet samples from both Whitby and Kimmeridge, and shows that the geological samples can be discriminated by differences in their organic components, as elucidated by Fourier transform infrared spectroscopy and pyrolysis-gas chromatography/mass spectrometry. 相似文献
997.
S. MANDAL 《Archaeometry》1997,39(2):289-308
There has been a long but sporadic history of research on stone axes in Ireland, leading to the formation of the Irish Stone Axe Project (ISAP) in 1990. The purpose of this paper is to outline the research strategy of the project and to indicate the petrological techniques that are being applied in parallel with archaeological and archival studies to classify and identify potential sources for Irish stone axes. These include macroscopic studies, transmitted and reflected light microscopy on polished thin sections and X-ray fluorescence analyses. The results of the macroscopic examination of 15916 axes indicate that one rock type, porcellanite, was the dominant source, but that a wide range of other lithologies was also exploited. Several avenues for more detailed research are highlighted. A case study of gabbro axes demonstrates the value of this systematic approach to stone axe studies, and the results of this study suggest that some of these axes are petrographically consistent with British Group I, presumed to originate from sources in Cornwall, south-west England. 相似文献
998.
Nikolai S. Rozov 《History and theory》1997,36(3):336-352
Karl Popper's critique of theoretical history remains formidable but contains serious flaws. Popper held erroneous views about the practice of the natural sciences and created overly severe strictures for theoretical statements in the social sciences. General theory and general theoretical statements play a legitimate role in the social sciences. Merton has promoted middle-range theories and models and Lakatos multiple ontologies. One can answer Popper's criticisms of either the impossibility or triviality of long-term historical laws by searching for stable constellations of local or middle-range laws rather than a universal law. Moreover, the successful use in the social sciences of various types of scales of measurement rather than an absolute scale shows that quantitative analysis is possible in history. Investigators need to find the boundaries, the frameworks of feasibility, in which historical trends and laws operate. Popper's maximalism plays into the irrationalist trends that he himself deplored. If historical investigators and theoreticians set appropriate goals for theoretical history, they can practice their discipline responsibly and find meanings, if not a single meaning, in history. 相似文献
999.
Ian A Simpson David Parsisson Nick Hanley Craig H Bullock 《Transactions (Institute of British Geographers : 1965)》1997,22(3):307-320
Environmentally Sensitive Areas (ESAs) designated under EC Structure Regulation 797/85 now cover 1.4 million ha of the Scottish countryside and are likely to make a substantial contribution to the regulation of landscape change. Visual changes to landscapes with (policy on) and without (policy off) the ESA programme in two Scottish ESA areas, Breadalbane and the Machair, are predicted through impact-assessment procedures and computer manipulation of photographic images. The methodological requirements for such predictions are outlined and substantial differences in landscape characteristics under policy on/off scenarios are revealed. Such approaches to landscape change are an essential foundation for the development of environmental cost-benefit analyses and will contribute to public consultation processes. 相似文献
1000.
Ian McIntosh 《Oceania; a journal devoted to the study of the native peoples of Australia, New Guinea, and the Islands of the Pacific》1997,67(4):273-288
Over the past forty years the Aboriginal people of Galiwin'ku (Elcho Island) in north-east Arnhem Land have successfully incorporated Christianity into their world view. However, a Uniting Church report characterises members of this same Yolngu (Aboriginal) community as being overwhelmed with feelings of inferiority and powerlessness and unable to function within structures established by Balanda (non-Aborigines). This paper contrasts the ways in which Christianity has helped break down the separation between cultural groups with its function as a structure for explicit discourse on Aboriginal/non-Aboriginal relations and inequality. While some Elcho Islanders see anthropologists as people who listen in order to work for Aborigines, Aboriginal Christians see them and other ‘scientists’ as attempting to undermine Aboriginal belief in the Christian God. They are seen as degrading a spiritual movement which has its foundation in the Dreaming and as posing a potential threat to the momentum of Aboriginal directed change in the community. 相似文献