全文获取类型
收费全文 | 4777篇 |
免费 | 201篇 |
出版年
2020年 | 81篇 |
2019年 | 100篇 |
2018年 | 138篇 |
2017年 | 141篇 |
2016年 | 173篇 |
2015年 | 109篇 |
2014年 | 129篇 |
2013年 | 1428篇 |
2012年 | 147篇 |
2011年 | 181篇 |
2010年 | 174篇 |
2009年 | 133篇 |
2008年 | 113篇 |
2007年 | 120篇 |
2006年 | 113篇 |
2005年 | 74篇 |
2004年 | 61篇 |
2003年 | 56篇 |
2002年 | 64篇 |
2001年 | 68篇 |
2000年 | 63篇 |
1999年 | 78篇 |
1998年 | 59篇 |
1997年 | 42篇 |
1996年 | 34篇 |
1995年 | 44篇 |
1994年 | 33篇 |
1993年 | 41篇 |
1992年 | 28篇 |
1991年 | 36篇 |
1990年 | 40篇 |
1989年 | 39篇 |
1988年 | 29篇 |
1987年 | 40篇 |
1986年 | 41篇 |
1985年 | 46篇 |
1984年 | 53篇 |
1983年 | 47篇 |
1982年 | 38篇 |
1981年 | 45篇 |
1980年 | 42篇 |
1979年 | 39篇 |
1978年 | 36篇 |
1977年 | 36篇 |
1976年 | 27篇 |
1975年 | 28篇 |
1974年 | 27篇 |
1973年 | 31篇 |
1972年 | 30篇 |
1970年 | 27篇 |
排序方式: 共有4978条查询结果,搜索用时 15 毫秒
991.
Prehistoric Settlement,Mobility and Societal Structure in the Peak District National Park: New Evidence from Ceramic Compositional Analysis
下载免费PDF全文
![点击此处可从《Archaeometry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Detailed compositional and technological analysis of a large assemblage of prehistoric ceramics from numerous sites situated within the Peak District National Park has been used to explore the settlement patterns, societal structure, mobility and interaction of the populations that inhabited this area during the Early Bronze Age to Early Iron Age. A surprising pattern emerges of the widespread dominance of a single, geographically restricted temper type, which appears to have been transported and mixed with locally procured clay and used to produce pottery at numerous different sites. The distribution of this and several other compositional groups are defined via thin‐section petrography and compared to raw material field samples. The resulting patterns are used to assess the validity of previous theories about prehistoric life in this region during the third to first millennia bc . 相似文献
992.
Lead Isotope Analysis of Tooth Enamel from a Viking Age Mass Grave in Southern Britain and the Constraints it Places on the Origin of the Individuals
下载免费PDF全文
![点击此处可从《Archaeometry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Lead analysis of tooth enamel from individuals recovered from a Viking Age burial pit in southern England provides further evidence for their childhood origins outside Britain. All except one of the men have very low Pb concentrations that exclude anthropogenic Pb exposure. Strontium and oxygen isotope compositions identify a core group of men who have Pb isotope compositions of 208Pb/206Pb = 2.065 ± 0.021 (n = 20, 2SD) that, when compared with data from European soils, appear to exclude a childhood in the Scandinavian countries of Norway, Sweden and Finland, whereas areas of Northern continental Europe cannot be excluded. 相似文献
993.
Evidence for Birch Bark Tar Use as an Adhesive and Decorative Element in Early Iron Age Central Italy: Technological and Socio‐Economic Implications
下载免费PDF全文
![点击此处可从《Archaeometry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Archaeological excavations carried out in Early Iron Age Vetulonia (northern Tuscany, Italy) brought to light a funerary urn particularly noteworthy for the presence of an unusual decoration obtained by plastering the vase surface with an organic dark grey substance, on which metal strips were originally fixed. In order to reveal the origin of such coating, it was chemically studied by gas chromatography coupled with mass spectrometry (GC/MS). Chemical analysis not only revealed that birch bark tar was used as coating/adhesive material for the manufacture of the urn, but also allowed us to discuss the significance of the vessel in terms of eco‐technological knowledge and possible cultural connections on a large geographical scale. 相似文献
994.
Entry into working life: Internal migration and the job match quality of higher‐educated graduates
下载免费PDF全文
![点击此处可从《Journal of regional science》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We estimate the impact of internal migration on job‐match quality for recent Dutch university and college graduates. We find positive yet modest wage returns. After controlling for the self‐selection of migrants with an IV approach, this effect is no longer significant for university graduates and all graduates from peripheral areas. We also find that, for our alternative job‐match measures, where there is evidence of migrant self‐selection, controlling for self‐selection strongly reduces the effect of internal migration on job‐match quality. In some cases, the returns on internal migration are found to be negative, which may signal forced migration. 相似文献
995.
996.
997.
An analysis of Forest Service-related legislative activity found that increasingly Congress is becoming involved in agency activities and decisionmaking. Congress's growing scrutiny and management of the Forest Service is indicated by rising trends in requests for agency testimony at congressional hearings, in the number of Forest Service-related bills and amendments introduced in Congress, and in the amount of Forest Service-related legislation enacted. Anecdotal evidence of direct political pressure imposed upon agency personnel by congressional members also indicates that much congressional influence occurs outside of these legislative activities. An examination of activities such as these and directives attached to annual appropriation bills also shows that not all congressional actions are productive in fostering positive agency change. The results of this study indicate the likelihood that Congress has been playing a major role in instigating change within the agency. 相似文献
998.
Interest groups involved in the Forest Service's 1990 Resources Planning Act (RPA) forest planning process and representatives from accredited forestry schools were surveyed via a written questionnaire on their perceptions of change within the Forest Service since 1976. Respondents felt that the agency had changed, particularly during the late 1980s and early 1990s. Consumptive users perceived the change to be negative, while non-consumptive user groups and forestry schools felt it was somewhat positive, although they still felt the Forest Service had much further to go in this direction before achieving these groups' desired priorities for National Forest management. These results indicate that the agency is undergoing a net shift in direction towards increased emphasis on non-commodity forest uses. In general, external forces, such as Congress and the courts, were seen as having a greater impact on agency change than were sources of change within the agency itself. Forestry schools agreed most often with non-consumptive users, indicating that these programs may be undergoing a change away from their traditional focus on timber production. In addition to providing valuable insights on the subject of change in the Forest Service, these survey results locate areas of agreement and disagreement, and provide valuable feedback to the agency regarding its constituent groups' views about its performance in managing the National Forests. 相似文献
999.
Lipid residues from two Late Saxon/early medieval ceramic vessels recovered from excavations at West Cotton, Raunds, Northamptonshire, U.K., have been investigated by high-temperature gas chromatography (GC) and GC/mass spectrometry (GC/MS). The solvent extracts of sherds sampled from different points on each vessel (i.e., base, body and rim) were analysed quantitatively and qualitatively and compounds were identified which were characteristic of beeswax and animal fat. Furthermore, by determining the sites of accumulation of the specific lipid types and their concentrations in different parts of the vessels it can be inferred that the beeswax was added to the vessels prior to the addition of the fat. It was concluded that the two vessels performed different functions in antiquity. 相似文献
1000.
The expression 'Information is power' is widely used, particularly with reference to the imminent 'Information Age'. Yet women must ask, 'Whose information?' and 'Whose power?' if, as a large body of scholarly literature has suggested, women's relationship to information technologies is somehow problematic. In this article, I argue that electronic networks, bulletin boards, online conferences and other computer-mediated communications emphasizing women's issues can recast traditional notions of the computer and its relationship with women. While historically, the dominant groups in many societies have used their command of communications technologies as a means to consolidate their power, new communications technologies escaping centralised political or legal control can diversify information and offer alternative courses of action. Computer-mediated communications on the Internet currently offer these options, yet their future is uncertain. Women who engage with information technologies as the technology and the regulatory framework develop have the opportunity to influence the deployment of this medium, which in turn may have consequences for their sociopolitical status. 相似文献