全文获取类型
收费全文 | 3074篇 |
免费 | 138篇 |
出版年
2020年 | 54篇 |
2019年 | 53篇 |
2018年 | 101篇 |
2017年 | 101篇 |
2016年 | 94篇 |
2015年 | 63篇 |
2014年 | 84篇 |
2013年 | 1060篇 |
2012年 | 84篇 |
2011年 | 84篇 |
2010年 | 78篇 |
2009年 | 66篇 |
2008年 | 72篇 |
2007年 | 61篇 |
2006年 | 52篇 |
2005年 | 35篇 |
2004年 | 50篇 |
2003年 | 41篇 |
2002年 | 32篇 |
2001年 | 30篇 |
2000年 | 24篇 |
1999年 | 29篇 |
1998年 | 27篇 |
1997年 | 23篇 |
1996年 | 19篇 |
1995年 | 23篇 |
1994年 | 27篇 |
1993年 | 19篇 |
1992年 | 24篇 |
1989年 | 23篇 |
1988年 | 18篇 |
1987年 | 19篇 |
1986年 | 20篇 |
1985年 | 24篇 |
1984年 | 30篇 |
1983年 | 31篇 |
1982年 | 23篇 |
1981年 | 24篇 |
1980年 | 25篇 |
1979年 | 29篇 |
1978年 | 29篇 |
1977年 | 28篇 |
1976年 | 24篇 |
1975年 | 25篇 |
1974年 | 18篇 |
1973年 | 26篇 |
1972年 | 18篇 |
1971年 | 22篇 |
1970年 | 17篇 |
1969年 | 23篇 |
排序方式: 共有3212条查询结果,搜索用时 203 毫秒
191.
192.
Within Iran, there is little archaeological evidence for relationships between newly arrived Early Trans-Caucasian (ETC) or Kura-Araxes settlers and earlier inhabitants and contact with neighbouring cultures, or for their apparently abrupt end. Based on the evidence, the Iranian Kura-Araxes was not a simple ‘copy' of the Caucasian Kura-Araxes package. Ceramic traditions show local peculiarities, and all are elements suggesting that the Kura-Araxes traditions went through processes of adaptation, change and re-elaboration according to local tastes and technologies. In this study, an archaeometric approach to ceramics in the Kolyaei Plain of central Zagros contributes to the discussion of contact and exchange between indigenous communities and several cultural spheres of influence on the Early Bronze Age (beginning in the fourth millennium bce ). Morphological data, as well as the mineralogical and chemical composition of ceramics, were applied to determine the major and trace elements of the pottery shards. Based on the trace element profiles, it can be suggested that all the pottery shards are in the same group and they strongly are local products. The ceramic provenance indicates the same patterns of material interactions during the ETC or Kura-Araxes in all the sites within the Kolyaei Plain. 相似文献
193.
G. A. De La Fuente V. G. Josa G. Castellano S. Limandri S. D. Vera J. F. Días S. Suárez G. Bernardi S. Bertolino 《Archaeometry》2020,62(2):247-266
Particle-induced X-ray emission (PIXE), X-ray diffraction (XRD), electron microprobe analysis (EDS) and scanning electron microscopy (SEM) analytical techniques were used to characterize surface paints in pre- and post-fired Aguada Portezuelo decorated pottery. Surface paintings in black, white, red, brown, burgundy and ochre were analysed. Major, minor and trace elements were detected by PIXE, whereas XRD and SEM-EDS gave information on the main mineral phases and the characteristic morphology for each analysed pigment. The results obtained indicate that the main colour groups can be easily discriminated by PIXE, and they are characterized by only one pigment for each colour: hematite (red) and manganese mineral oxides (black), respectively, whereas white pigments are characterized by calcite, ghelenite and gypsum. 相似文献
194.
Since Marshall (1890), it has been widely held in urban economic theory that cities insure workers against the risk of unemployment by offering a larger pool of potential jobs. Using a large administrative panel data set on workers displaced as a result of plant closures, we examine whether positive effects from a higher urban job density are offset by more intense competition between workers. When controlling for the sorting of workers between regions, we find robust evidence that the effect of job competition on unemployment duration exceeds that of job opportunities in absolute value. Our results put the idea of urban risk-sharing into perspective and provide an explanation for observed longer unemployment durations in cities. 相似文献
195.
196.
Stephen F. Poropat Jay P. Nair Caitlin E. Syme Philip D. Mannion Paul Upchurch Scott A. Hocknull 《Alcheringa: An Australasian Journal of Paleontology》2017,41(4):543-580
Poropat, S.F., Nair, J.P., Syme, C.E., Mannion, P.D., Upchurch, P., Hocknull, S.A., Cook, A.G., Tischler, T.R. &; Holland, T. XX.XXXX. 2017. Reappraisal of Austrosaurus mckillopi Longman, 1933 from the Allaru Mudstone of Queensland, Australia’s first named Cretaceous sauropod dinosaur. Alcheringa 41, 543–580. ISSN 0311-5518Austrosaurus mckillopi was the first Cretaceous sauropod reported from Australia, and the first Cretaceous dinosaur reported from Queensland (northeast Australia). This sauropod taxon was established on the basis of several fragmentary presacral vertebrae (QM F2316) derived from the uppermost Lower Cretaceous (upper Albian) Allaru Mudstone, at a locality situated 77 km west-northwest of Richmond, Queensland. Prior to its rediscovery in 2014, the type site was considered lost after failed attempts to relocate it in the 1970s. Excavations at the site in 2014 and 2015 led to the recovery of several partial dorsal ribs and fragments of presacral vertebrae, all of which clearly pertained to a single sauropod dinosaur. The discovery of new material of the type individual of Austrosaurus mckillopi, in tandem with a reassessment of the material collected in the 1930s, has facilitated the rearticulation of the specimen. The resultant vertebral series comprises six presacral vertebrae—the posteriormost cervical and five anteriormost dorsals—in association with five left dorsal ribs and one right one. The fragmentary nature of the type specimen has historically hindered assessments of the phylogenetic affinities of Austrosaurus, as has the fact that these evaluations were often based on a subset of the type material. The reappraisal of the type series of Austrosaurus presented herein, on the basis of both external morphology and internal morphology visualized through CT data, validates it as a diagnostic titanosauriform taxon, tentatively placed in Somphospondyli, and characterized by the possession of an accessory lateral pneumatic foramen on dorsal vertebra I (a feature that appears to be autapomorphic) and by the presence of a robust ventral mid-line ridge on the centra of dorsal vertebrae I and II. The interpretation of the anteriormost preserved vertebra in Austrosaurus as a posterior cervical has also prompted the re-evaluation of an isolated, partial, posterior cervical vertebra (QM F6142, the ‘Hughenden sauropod’) from the upper Albian Toolebuc Formation (which underlies the Allaru Mudstone). Although this vertebra preserves an apparent unique character of its own (a spinopostzygapophyseal lamina fossa), it is not able to be referred unequivocally to Austrosaurus and is retained as Titanosauriformes indet. Austrosaurus mckillopi is one of the oldest known sauropods from the Australian Cretaceous based on skeletal remains and potentially provides phylogenetic and/or palaeobiogeographic context for later taxa such as Wintonotitan wattsi, Diamantinasaurus matildae and Savannasaurus elliottorum.Stephen F. Poropat* [sporopat@swin. edu. au; stephenfporopat@gmail. com] Department of Chemistry and Biotechnology, Swinburne University of Technology, John St, Hawthorn, Victoria 3122, Australia; Jay P. Nair [j. nair@uq. edu. au; jayraptor@gmail. com] School of Biological Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia; Caitlin E. Syme [caitlin. syme@uqconnect. edu. au] School of Biological Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia; Philip D. Mannion [philipdmannion@gmail. com] Department of Earth Science and Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK; Paul Upchurch [p. upchurch@ucl. ac. uk] Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, UK; Scott A. Hocknull [scott. hocknull@qm. qld. gov. au] Geosciences, Queensland Museum, 122 Gerler Rd, Hendra, Queensland 4011, Australia; Alex G. Cook [alex. cook@y7mail. com] School of Earth Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia; Travis R. Tischler [travisr. tischler@outlook. com] Australian Age of Dinosaurs Museum of Natural History, Lot 1 Dinosaur Drive, PO Box 408, Winton, Queensland 4735, Australia; Timothy Holland [drtimothyholland@gmail. com] Kronosaurus Korner, 91 Goldring St, Richmond, Queensland 4822, Australia. *Also affiliated with: Australian Age of Dinosaurs Museum of Natural History, Lot 1 Dinosaur Drive, PO Box 408, Winton, Queensland 4735, Australia. 相似文献
197.
Stephanie Döpper 《Arabian Archaeology and Epigraphy》2017,28(2):190-208
A third‐millennium BC tomb was subject to a rescue excavation in connection with the construction of a new road near the village of Al‐Khubayb in the Sultanate of Oman. It yielded a small number of finds, especially small metal objects that belonged to a later reuse of the tomb in the Samad period. As all diagnostic finds from the tomb date to the reuse, its architectural elements were the only indicator for the construction date of the tomb. Besides its small size and large wall thickness, which might suggest that the tomb is a transitional type between the Hafit and the Umm an‐Nar periods, its separation into two chambers and its facade made of white, dressed stones, can be seen as a clue for a construction date of the tomb in the Umm an‐Nar period. 相似文献
198.
ABSTRACTRecent scholarly work has enhanced our understanding of how new path development activities are enabled or constrained by ‘regional environments’, made up of pre-existing industrial structures, knowledge organizations, support structures and institutional configurations. This paper moves beyond overly static views on regional environments. We develop a dynamic perspective by analysing conceptually and empirically how a constraining environment can be transformed into one that enables the development of new growth paths. The paper offers a typology of various modes of change, including layering, adaptation and novel application that are used by key actors to ‘manipulate’ the regional support structures to facilitate new regional industrial path development. The conceptual framework is applied to a case study of the digital games industry in the region of Scania, southern Sweden. Our findings suggest that the creation of a more enabling environment for the growth of the digital games industry has been the outcome of multi-scalar processes and combinations of various modes of change employed by a few key individuals operating in the newly emerging path. 相似文献
199.
Methods to record shipwreck sites have evolved considerably in the past two decades. Digital technology and marine robotics regularly present faster and more precise ways to excavate, clean, tag, and record ship remains, while computers simplify many of the steps involved in the reconstruction of ships from their archaeological remains. At the same time, the internet is creating opportunities to share primary data in real time and on a wide scale. This paper presents a methodology used by the authors to record and reconstruct the wooden structures of a 19th-century shipwreck in southern Brazil (Lagoa do Peixe site) and of a 16th-century shipwreck in Croatia (the Gnali? shipwreck). 相似文献
200.