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   2292篇
  免费   91篇
  2024年   3篇
  2023年   34篇
  2022年   7篇
  2021年   11篇
  2020年   49篇
  2019年   62篇
  2018年   377篇
  2017年   289篇
  2016年   320篇
  2015年   76篇
  2014年   72篇
  2013年   215篇
  2012年   79篇
  2011年   192篇
  2010年   205篇
  2009年   67篇
  2008年   95篇
  2007年   85篇
  2006年   6篇
  2005年   42篇
  2004年   14篇
  2003年   7篇
  2002年   11篇
  2001年   15篇
  2000年   4篇
  1999年   3篇
  1998年   2篇
  1997年   4篇
  1996年   6篇
  1995年   11篇
  1994年   3篇
  1993年   4篇
  1992年   4篇
  1988年   1篇
  1985年   2篇
  1984年   1篇
  1982年   2篇
  1981年   1篇
  1979年   1篇
  1973年   1篇
排序方式: 共有2383条查询结果,搜索用时 250 毫秒
81.
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   
82.
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   
83.
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   
84.
85.
This article aims at presenting and discussing the strategies for updating the finite element numerical modeling of stone masonry arch bridges using operational modal analysis. The study comprehended three bridges: two old ones, the St. Lázaro and the Lagoncinha bridges, and a recently constructed bridge in Vila Fria, Portugal. Updating of the bridge models is performed by comparing the numerical and experimental modal parameters. Three-dimensional detailed numerical models are used to perform modal analysis of the bridges. Experimental modal identification of the bridges is based on the measurement of their acceleration responses during normal operation. The assigned material properties are also based on available results obtained from in situ and laboratory tests and on the results of visual inspection and historical research carried out for both old bridges.  相似文献   
86.
In this article, I explore the parallel responses of two groups of colonial subjects who were confronted with the institutional changes that occurred in the context of Enlightenment ideas in eighteenth-century Mexico: creole clerics headed by the Jesuit Francisco Javier Clavijero; and native religious men who petitioned to colonial authorities and the Crown for additional spaces for the education of indigenous men. I explore some of the interactions between creole clerics—often referred to as creole patriots—and native elites in the schools of central Mexico, and efforts by indigenous noble men to broaden the opportunities for natives to join the ranks of the Church and to receive a higher education. To this end, I build on the scholarship that has made evident how the hegemonic program of Bourbon reforms, which was inspired by the Enlightenment, was not a top-down plan implemented successfully and equally across the continent but rather a series of contested interpretations. This article contributes to the recent shift in the scholarship on the Enlightenment that acknowledges cross-cultural global exchanges by arguing that certain groups of natives in central Mexico, and a particular group of American-born clerics, participated actively in building a pragmatic version of the Enlightenment that responded to their local realities and contributed to a globalized understanding of enlightened ideas.  相似文献   
87.
88.
Territorial capital has gained considerable attention in the past few years. The aim with this work is to throw light on some underlying aspects of territorial capital research. The study focuses on the theoretical and empirical issues of territorial capital and highlights some critical remarks related to the topic. On the one hand, the focus of the study is on the comparison of concepts and approaches in connection with territorial capital; then an in-depth look is taken at “capital frameworks” related to the research field. On the other hand, a comprehensive overview is presented of empirical investigations by comparing the applied methods, dimensions and variables of territorial capital. An argument is also made for a critical assessment concerning the topic with regard to the sense and function of territorial capital in regional economics and local economic development and highlights some further dilemmas concerning the “properties of capital” and “territorial capital paradigm”. Finally, some suggestions are provided for the future of territorial capital analysis. The main result of the study is an own belief in the concept of territorial capital.  相似文献   
89.
The objective of this paper is to assess an approach to statistical modeling of point referenced establishment data that permit inclusion of “environmental” or establishment‐specific covariates and specific forms of interestablishment interaction. Gibbs models are used to decompose the conditional intensity of the spatial point process into trend and interaction components. The trend is composed of access measures (primarily different classes of roads) and three different interaction processes are tested: Geyer, area interaction, and Strauss hard core. While the models used have proved to be useful in ecology, we are unaware of any applications to establishment or firm data. In empirical application, the models yield intuitively appealing results for the trend component, and the ability to specify the interaction component gives deeper insights into interestablishment spatial dynamics than any previously published methods.  相似文献   
90.
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