全文获取类型
| 收费全文 | 11046篇 |
| 免费 | 198篇 |
专业分类
| 11244篇 |
出版年
| 2021年 | 79篇 |
| 2020年 | 186篇 |
| 2019年 | 229篇 |
| 2018年 | 229篇 |
| 2017年 | 293篇 |
| 2016年 | 356篇 |
| 2015年 | 250篇 |
| 2014年 | 248篇 |
| 2013年 | 2270篇 |
| 2012年 | 299篇 |
| 2011年 | 337篇 |
| 2010年 | 360篇 |
| 2009年 | 314篇 |
| 2008年 | 337篇 |
| 2007年 | 300篇 |
| 2006年 | 266篇 |
| 2005年 | 249篇 |
| 2004年 | 210篇 |
| 2003年 | 159篇 |
| 2002年 | 182篇 |
| 2001年 | 180篇 |
| 2000年 | 173篇 |
| 1999年 | 187篇 |
| 1998年 | 123篇 |
| 1997年 | 85篇 |
| 1996年 | 92篇 |
| 1995年 | 97篇 |
| 1994年 | 95篇 |
| 1993年 | 100篇 |
| 1992年 | 103篇 |
| 1991年 | 79篇 |
| 1990年 | 86篇 |
| 1989年 | 84篇 |
| 1988年 | 96篇 |
| 1987年 | 101篇 |
| 1986年 | 105篇 |
| 1985年 | 132篇 |
| 1984年 | 134篇 |
| 1983年 | 138篇 |
| 1982年 | 105篇 |
| 1981年 | 116篇 |
| 1980年 | 122篇 |
| 1979年 | 109篇 |
| 1978年 | 96篇 |
| 1977年 | 120篇 |
| 1976年 | 91篇 |
| 1975年 | 101篇 |
| 1974年 | 100篇 |
| 1973年 | 86篇 |
| 1971年 | 77篇 |
排序方式： 共有10000条查询结果，搜索用时 0 毫秒
911.
A. DURAN M. C. JIMENEZ DE HARO J. L. PEREZ‐RODRIGUEZ M. L. FRANQUELO L. K. HERRERA A. JUSTO 《Archaeometry》2010,52(2):286-307
The employment of synchrotron techniques complemented by conventional laboratory systems has allowed us to deepen and improve our knowledge of Roman wall painting procedures. The palette identified in wall paintings from Pompeii and Herculaneum from the second century bc includes goethite, hematite, cinnabar, glauconite, Egyptian blue, and other components such as calcite and aragonite. Proof of the use of organic binders is provided by FTIR and PY–GC/MS. Therefore, the possibility of the use of ‘a secco’ techniques cannot be ruled out. Pigments in wall paintings are usually found in small percentages and conventional X‐ray diffractometers do not detect them. Synchrotron radiation – high‐resolution X‐ray powder diffraction has allowed identification with only a few micrograms of sample. 相似文献
912.
Using Raman spectroscopy, energy-dispersive X-ray fluorescence and X-ray diffraction, the Pb–Sn–Sb triple oxide yellow and lead–tin yellow have been identified on two pieces of cloisonné enamel (Falangcai) porcelains. Lead–tin yellow and lead antimonate yellow have been identified on famille rose porcelains manufactured before and after 1911, respectively. The replacement of the Pb–Sn–Sb triple oxide yellow by lead–tin yellow and that of the lead–tin yellow by lead antimonate yellow are discussed. 相似文献
913.
This paper presents material characteristics and raw material provenance of the stone moulds for bronze slender daggers from Galdong. This type of bronze dagger is uniquely distributed in the Korean Peninsula and these stone moulds were the first to be found by excavation. The stone moulds were made of igneous hornblendite with course-grained holocrystalline textures. Based on petrological, mineralogical and geochemical characteristics, the original rock materials of the moulds were inferred to be derived from the Jangsu or Namwon areas which are about 50 km away from the excavation site. It is a notable achievement that this provenance study confirmed the domestic production of Korean-styled daggers. 相似文献
914.
A. E. Van der Merwe G. J. R. Maat M. Steyn 《International Journal of Osteoarchaeology》2010,20(2):227-239
Examination of the histological structure of bone not only helps investigators to estimate age at death but can also aid in the diagnosis of palaeopathological lesions. The purpose of this paper is to assess whether histological features as described in the literature can confirm the macroscopic diagnoses of ossified subperiosteal haematomas associated with healed scurvy and syphilitic bone changes observed on the anterior tibiae of individuals from a 19th century mining community from Kimberley South Africa. The frequent occurrence of these two diseases amongst the deceased was well established in related hospital documents and governmental documents. A section of bone was removed from lesions on the tibiae of 14 individuals. These bone changes were macroscopically diagnosed as being indicative of either treponematosis ossified subperiosteal haematomas or non‐specific periostitis. Cross‐sections were prepared for microscopic investigation using a manual ground section technique. Ossified haematomas were histologically identified in seven individuals. These sections were characterised by normal cortical bone an intact original periosteal surface and newly formed radiating trabecular bone apposing it. Three phases of ossified subperiosteal haematoma formation and remodelling could be distinguished. Infectious bone changes most likely associated with treponematosis were observed in one individual. These were characterised by lysis and numerous resorption holes/channels. No clear distinction could be made between the internal spongy cortical or newly formed bone. Histological features described by some authors as characteristic of this condition could not be identified. In addition three individuals presented with microscopic features indicative of both the aforementioned bone affections and three did not show any pathological changes on microscopic level. It was concluded that although specific pathological conditions can most likely not be diagnosed purely on the basis of histomorphological observations broad distinctions could be made between lesions caused by the ossification of subperiosteal haematomas and bone changes due to infectious diseases. Copyright © 2009 John Wiley & Sons Ltd. 相似文献
915.
Cranioplasty is a well‐known procedure in modern neurosurgery. Although some authors have claimed it was also performed by prehistoric trepanners in various parts of the world, there is little hard evidence to support this. Here we review various claims of cranioplasty in Peru, where trepanation was widely practised in Prehispanic times. We find little support for assertions that cranioplasty was common. One recently discovered burial from the Cuzco region, however, provides the first documented case of the reinsertion of a bone plug into a trepanation opening. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
916.
The presence of the osseous remains of at least four mules in a garbage dump at the Roman fort of Biriciana near the town of Weißenburg, Upper Bavaria, dating to c. 160 AD, raised the question as to whether mule breeding was already performed to the north of the Alps during the Middle Roman Empire, or whether these animals still had to be imported from the Mediterranean. Serial analyses of the dental enamel and dentine of a lower fourth premolar and the surrounding alveolar bone of a mandible of a mule in terms of stable strontium isotopic ratios of the apatite, and stable carbon and oxygen isotope ratios of the structural carbonate, were carried out to test whether this individual moved long distances during its lifetime. Since isotopic ratios obtained by serial analysis can be correlated with consecutive ontogenetic stages, it can be assumed that this particular individual experienced significant changes in terms of diet and environmental parameters after its eighth year of life. These changes included a period of residence in a region of high altitude, most likely the Alps considering the location of the Roman fort where the mule was found. The isotopic data obtained do not contradict the assumption that this animal was bred and raised in northern Italy, to frequent later in its adult life the Alps and finally perish at Biriciana/Weißenburg. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
917.
The study of ancient DNA (aDNA) using molecular methods is an increasingly valuable tactic in bioarchaeology. While this method must be carefully undertaken to ensure that the molecules detected are representative of the ancient sample and not modern contaminates, there is a danger that a ‘one size fits all’ approach to validation will lead to misinterpretation and/or missed opportunities of valuable findings. When comparing human and pathogen aDNA, there are many shared technical means that can ensure best practice. However, there are a number of assumptions that should not be used for both scenarios. We discuss these aspects in reference to a recent article published by this journal and highlight some of the latest advances in molecular detection of ancient pathogen DNA that can further improve this endeavour. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
918.
919.
J.M. POWELL 《Geographical Research》2010,48(3):249-264
James Arthur Prescott was a prominent soil scientist whose career responded to an increasingly complex, recognisably Australian web of interpenetrating spatial scales, served to promote revolutionary global advances in his chosen field, and in the process negotiated the blurred boundaries between ‘pure’ and ‘applied’ research. Encounters with this instructive life suggest that, while resolutions of pivotal anxieties might turn on ineluctably personal qualities, they also reflect a dynamic interplay between international, imperial, national and state contexts. Prescott's innovative contributions to soil science, fruits of a tenaciously consolidated career, influenced resource appraisal and environmental management across a prodigious continental expanse. A sustained focus on local and regional development brought him into contact with a wide range of contemporaries, including pioneering geographers, and culminated in his election to a Fellowship of the Royal Society. 相似文献
920.
Over the past decade social exclusion has increasingly been positioned at the forefront of political, academic and lay discourse as the cause of disadvantage. While the definition, measurement and solutions to social exclusion remain open to debate, housing has progressively been positioned as a central variable creating neighbourhoods of exclusion. Much of this debate has positioned areas of public housing as being the most disadvantaged and socially excluded neighbourhoods. However, the multidimensionality of social exclusion brings into question the simple identification of areas of public housing as being the most excluded. By exploring six dimensions of exclusion (neighbourhood, social and civic engagement, access, crime and security, community identity and economic disadvantage) we explore the differences between areas dominated by public housing and those characterised by private market housing in terms of their scores on each of these individual dimensions of exclusion. We find that it is the experience of households with multiple dimensions of exclusion, especially locational and economic disadvantage, that differentiate areas of public housing from private housing locations. 相似文献