全文获取类型
收费全文 | 2583篇 |
免费 | 421篇 |
出版年
2024年 | 4篇 |
2023年 | 7篇 |
2022年 | 23篇 |
2021年 | 49篇 |
2020年 | 65篇 |
2019年 | 192篇 |
2018年 | 181篇 |
2017年 | 160篇 |
2016年 | 192篇 |
2015年 | 152篇 |
2014年 | 134篇 |
2013年 | 331篇 |
2012年 | 187篇 |
2011年 | 179篇 |
2010年 | 149篇 |
2009年 | 98篇 |
2008年 | 147篇 |
2007年 | 140篇 |
2006年 | 104篇 |
2005年 | 108篇 |
2004年 | 74篇 |
2003年 | 86篇 |
2002年 | 60篇 |
2001年 | 65篇 |
2000年 | 55篇 |
1999年 | 21篇 |
1998年 | 8篇 |
1997年 | 12篇 |
1996年 | 9篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
排序方式: 共有3004条查询结果,搜索用时 15 毫秒
101.
This paper describes the archaeometric research conducted at the SLOWPOKE Reactor Facility of the University of Toronto (SLOWPOKE‐Toronto) during its existence from 1971 to 1998. The contributions to student teaching and research are described, and the total contribution of the facility to studies of an eclectic assortment of ancient and historic materials is addressed. 相似文献
102.
Archaeological bones, found close to Mexico City (Tlatelcomila), with alterations due to probable thermal exposure attributed to a possible case of cannibalism, have been characterized by XRD, SAXS and SEM. It is shown how these non‐destructive techniques, which are not conventionally used in archaeological research, may provide useful information. The deterioration degree of the bone structure is quantified through parameters such as gyration radius or fractal dimension. As some of the reported modifications could be attributed to diagenesis, a discussion is presented in terms of bone crystallinity and ionic exchange. Furthermore, the hydroxyapatite crystallite size increased depending on colour: this feature is not explained by diagenesis—it can only be attributed to temperature. We conclude that the samples were thermally treated. Indeed, thermal treatment alters the structure and morphology of bone at a very fine level (microscopic and nanometric), while morphology follows the structural modifications. It is determined that the studied human bones were treated at three different temperatures close to 100, 250 and 600°C. Therefore, they were either boiled (barbacoa) or grilled. 相似文献
103.
The calcareous skeletal remains of various microscopic organisms such as foraminifera and ostracods are a striking feature of thin sections of many archaeological ceramics from the Aegean Bronze Age. While the presence of these calcareous microfossils in pottery has been noted for some time, attempts to utilize them to further the aims of ceramic compositional analysis have been few in number. In the following paper, we take a first detailed look at the occurrence and utility of calcareous microfossils in archaeological ceramics. By presenting selected case studies from the Bronze Age of Crete, we demonstrate the potential of calcareous microfossils, especially the extremely small ‘nannofossils’ and the highly contextual geological information that they contain, in terms of the characterization and grouping of ceramics, the determination of their provenance and the reconstruction of ancient technology. 相似文献
104.
I. K. BAILIFF 《Archaeometry》2007,49(4):827-851
Fired clay brick samples, obtained from a group of seven high‐status late‐medieval and post‐medieval buildings in England ranging in age from c. ad 1390 to 1740, were dated by the luminescence method using an optically stimulated luminescence (OSL) technique. The results obtained indicate that, when applied to quartz extracted from brick, the technique is capable of producing dates that are in consistently good agreement with independent dating evidence for the buildings. For six samples taken from a group of four dating ‘control’ buildings the mean difference between the central values of luminescence and assigned ages was 5 ± 10 years (SD, n = 6). The methodology used is appropriate for application to other standing buildings in other temporal and geographic regions, and may be used with confidence where conventional dating methods are less certain. The study also examines the luminescence characteristics of quartz and the characteristics of the lithogenic radionuclides in brick samples and identifies various aspects related to the assessment of experimental uncertainty in testing the reliability of the method. 相似文献
105.
Dinah A. Koehler 《政策研究杂志》2007,35(4):689-722
Voluntary environmental programs (VEPs) have been used as a policy tool in the United States since the early 1990s and come in many forms. Early assessments of VEPs targeting changes in production processes showed that industrial participants improved their environmental performance and VEPs were celebrated as a viable alternative to more traditional regulation. Recent analyses using more sophisticated techniques, however, paint a less favorable picture. On the one hand, firms appear willing to sign up to VEPs, and in some cases, participants may be able to create a shield against future losses in shareholder value. On the other hand, these VEPs targeting production processes appear not to generate significant pollution abatement. The latter finding is particularly disturbing and this article discusses various explanations, including institutional failure and participant motivations. Future research needs to focus on understanding the firm motivation to invest in production‐related pollution abatement under a VEP. For policymakers, the research offers a warning on the limited impact to date of VEPs targeting production processes. However, the multitude of other VEPs, such as those which target new product development and changing market demands, merit a closer look to determine the overall potential of VEPs to engender positive environmental change. 相似文献
106.
Martina Heßler 《Berichte zur Wissenschaftsgeschichte》2007,30(2):145-160
Science Cities: What the Concept of the Creative City Means for Knowledge Production. – The article aims to show that the relationship of science and the city has changed since the 1970s in the context of the knowledgeable society. While cities have principally been regarded as the typical space of science, of new ideas and innovation for centuries, since the 1960s and 1970s universities, research institutes as well as industrial research institutes have relocated to the periphery of cities. There, however, these sites of knowledge have been organized in an ‘urban mode’. That means that the concept of the city as a place of science and innovation has determined the architectural, spatial, and social organization of these sites on the periphery of cities. Certain features of the city have been copied, such as social infrastructures, places of communication, restaurants, cafes etc., while others have been left out – housing, cinema, theatre etc. An ‘urban mode of knowledge production’ in the sense of a very stylized model of the city has become a tool to enhance the production of scientific and technological knowledge. – The article exemplifies this by focusing on a case study, namely of the so‐called ‘Science City’ of the Siemens Company in Munich‐Neuperlach. 相似文献
107.
Annett Steinführer Annegret Haase 《Geografiska annaler. Series B, Human geography》2007,89(2):183-195
Contemporary cities in East Central Europe (ECE) represent a hybrid type of urban development which is still generally considered to be a special case and is only exceptionally referred to in the recently intensified debate over the European city. Our paper argues that such exclusion is short‐sighted because ECE cities face structural problems similar to those of their Western pendants. Therefore, the contextual frame of urban research needs to be widened and can no longer be restricted to post‐socialist transition. In this regard, one of the main challenges for future urban development will be the consequences of demographic change. Ageing, new patterns of fertility behaviour and more diversified household structures in line with the Second Demographic Transition (SDT) will have significant implications for urban structures and housing markets, as already known for Western Europe. The purpose of this paper is to work out new questions and hypotheses for future urban research with special respect to Polish and Czech cities. Besides West European experience, recent developments in eastern Germany are taken as a frame of reference, assuming that this specific transition case may, in many respects, be regarded as a forerunner for similar developments in its neighbouring countries. 相似文献
108.
109.
论产业集群在提升城市竞争力中的综合功效 总被引:1,自引:0,他引:1
本文通过对产业集群在提升城市竞争力中的功效分析,指出政府在培育和发展产业集群中应发挥重要作用。 相似文献
110.