首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1359篇
  免费   3篇
  2023年   5篇
  2020年   8篇
  2019年   3篇
  2018年   274篇
  2017年   196篇
  2016年   237篇
  2015年   8篇
  2014年   9篇
  2013年   17篇
  2012年   28篇
  2011年   157篇
  2010年   173篇
  2009年   37篇
  2008年   71篇
  2007年   72篇
  2005年   29篇
  2004年   8篇
  2003年   3篇
  2000年   1篇
  1999年   2篇
  1988年   1篇
  1987年   7篇
  1986年   5篇
  1985年   3篇
  1984年   4篇
  1983年   3篇
  1980年   1篇
排序方式: 共有1362条查询结果,搜索用时 18 毫秒
41.
A reference sample of dental and oral nonmetric traits should represent its biological population from which it stems. The presence of individuals born at different times, different regions, and separate countries in the Coimbra-identified cranial collections provides the test of whether this sample reflects the biological continuity of this Portuguese sample among the late modern (early industrialization, nineteenth century) to early contemporary (early demographic transition, first half of the twentieth century) population of this region of central Portugal. The Coimbra collections were scored for 61 traits using methodology by Hauser and De Stefano (1989), Turner et al. (1991), Scott and Turner (1997), Irish (1998), and Marado and Silva (2016). The 600 individuals in the sample were divided by generation, region, and nationality. Their phenetic diversity was tested with principal component analysis and with the mean measure of divergence statistic. The proximity between the subsamples was generalized, and it mimicked previous genetic marker results. Some small subsamples hindered conclusions; nevertheless, this Coimbra sample is considered a reliable dental reference sample for the Portuguese late modern/early contemporary population.  相似文献   
42.
Elemental analyses and microstructural studies of historical metal artifacts provide researchers with invaluable and priceless information about metal extraction technology and the procedure of creating artifacts. In addition, the information is helpful for knowing about the metallurgical processes of the artifacts. This study was conducted by a microscopic examination and elemental analyses of seven Sasanian silver coins preserved in the Sistan Anthropology Museum, Iran. For the purpose of this study, three methods were employed: first, the proton induced X-ray emission microanalysis (micro-PIXE), to determine the main and trace elements of the coins; second, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), to perform elemental analysis to identify impurities of the metal; and third, microstructural analysis of the coins which was carried out with an optical microscope (OM). The elemental analyses identified Ca, Cu, Ag, Au, and Pb in the coins. The high quantity of Ag in samples validated the application of advanced and accurate cupellation technology for refining silver and separating impurities from raw ore. The gold concentration in the coins indicated the use of non-galena ore for silver extraction. Additionally, the microstructural analyses of samples pointed to the application of thermo-mechanical processes on coins.  相似文献   
43.
44.
The aim of this work is to characterize the original concrete from Roman buildings for public spectacles, theatre and amphitheatre, from Emerita Augusta, Mérida, Spain. An advanced knowledge of the Roman concrete composition is required for a reliable restoration and preservation of these ancient monuments. The concrete was studied through mineralogical (optical polarized microscopy and X-ray diffraction) and petrophysical (bulk and real density, open porosity to water and Hg, mechanical strength and ultrasonic velocity) analyses. With this work, it is possible to fill the gap that exists in this field and the characterization of the materials used in the Roman concrete from these two buildings, never previously studied, despite the significance of this archaeological ensemble, declared a World Heritage Site by UNESCO in 1993. The results allowed us to determine the composition of the Roman concrete and to infer the provenance of the aggregates used in these monuments.  相似文献   
45.
Sex estimation of skeletal remains is one of the major components of forensic identification of unknown individuals. Teeth are a potential source of information on sex and are often recovered in archaeological or forensic contexts due to their post-mortem longevity. Currently, there is limited data on dental sexual dimorphism of archaeological populations from Iran. This paper represents the first study to provide a dental sex estimation method for Iron Age populations. The current study was conducted on the skeletal remains of 143 adults from two Iron Age populations in close temporal and geographic proximity in the Solduz Valley (West Azerbaijan Province of Iran). Mesiodistal and buccolingual cervical measurements of 1334 maxillary and mandibular teeth were used to investigate the degree of sexual dimorphism in permanent dentition and to assess their applicability in sex estimation. Data was analysed using discriminant function analysis (SPSS 23), and posterior probabilities were calculated for all produced formulae. The results showed that incisors and canines were the most sexually dimorphic teeth, providing percentages of correct sex classification between 86.4 and 100 % depending on the measurement used. The combination of canines and other teeth improved significantly the level of correct sex classification. The highest percentages of sex classification were obtained by the combination of canines and incisors (100 %) and canines and molars (92.3 %). The present study provided the first reference standards for sex estimation using odontometric data in an Iranian archaeological population. Cervical measurements were found to be of value for sex assessment, and the method presented here can be a useful tool for establishing accurate demographic data from skeletal remains of the Iron Age from Iran.  相似文献   
46.
Determining hand laterality during human evolution is important in order to identify brain hemispheric lateralization for motor tasks and, indirectly, to gain information on the complex cognitive functions of the human brain. In this paper, we present a new method for inferring handedness from lithic evidence. The study is based on an analysis of the scatter patterns of lithic remains from stone-knapping episodes. An experimental programme was carried out by 14 knappers (eight right-handed and six left-handed), ranging from individuals that had never even struck two pebbles together to individuals who were quite familiar with prehistoric tools and had some degree of practice. The results of the experiment show that the material scatter patterns of right- and left-handed knappers at group level are different, but they do overlap at certain intervals. At the individual level, the probability of falsely ascribing left- and right-handedness has also been estimated. In addition, we have adapted this method to be applied to the archaeological record. In this case, only well-preserved knapping events with no post-depositional alterations can be used to assign left- or right-handed knappers, with the former being more reliably detected than the latter.  相似文献   
47.
Cleantech has emerged in the last decade as a major new investment sector at the forefront of the green economy. It responds to the need for innovative technologies to combat the impact of global environmental, climate and resource trends. Focusing on the cleantech sector, this article explores the central importance of relationality within the financial domain of the green economy. The central aim of this article is to deepen understandings of the operation of cleantech investment by examining the decision‐making processes of cleantech actors, how these are influenced by (and influence) cleantech investment networks, and the relationships between these factors and the macro‐level drivers and discourses focused on the cleantech sector. A relational economic geography approach is used in conjunction with other frameworks (spanning the cultural, structural and actor‐network dimensions of cleantech investment) to investigate: how cleantech investors define the sector; the macro‐ and micro‐level drivers of cleantech investment; and how cleantech networks form and operate to create and disseminate cleantech discourses and to generate the mutual trust and information sharing needed to secure cleantech investments. In so doing, the article seeks to shed greater light on the micro‐level processes contributing to the creation and growth of cleantech investment markets as an essential catalyst and component of the green economy.  相似文献   
48.
49.
Federico Ferretti 《对极》2016,48(3):563-583
This paper addresses the work of early critics of colonialism and Eurocentrism within Italian geography in the Age of Empire. At that time, a minority but rather influential group of Italian scholars, influenced by the international debates promoted by the anarchist geographers Reclus, Kropotkin and Me?nikov, fumed publicly at Italy's colonial ambitions in Africa. Their positions assumed, at least in the case of Arcangelo Ghisleri, the character of a radical critique of both political and cultural European hegemony. These approaches were linked to a similar critique of “internal colonialism”, both Austrian in the Italian‐speaking regions of Trento and Trieste, and Piedmontese in southern Italy. Based on primary sources, and drawing on the international literature on imperial geography and colonial and postcolonial sciences, this paper conjures up the Italian example to discuss how some European geographers of the Age of Empire were also early critics of racism, colonialism and chauvinism, and how these historical experiences can serve current debates on critical, radical and anarchist geographies.  相似文献   
50.
In 1665, Robert Hooke published his major work in microscopy, Micrographia, a defense of experimental philosophy. The following year, Margaret Cavendish, Duchess of Newcastle, published at her own expense a treatise and a novel that undermined the basis of this new science. The dispute broke out at the initiative of the Duchess, in the context of a vast controversy about the legitimacy and the efficiency of optical instruments in natural philosophy. All the figures of the dual are used, except one: the counterattack. Cavendish, indeed, was alone on the battlefield. Is it possible to call a dual a battle with only one combatant? This particular case of dispute that stops owing to the shortage of combatants is the subject of this article.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号