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   75篇
  免费   2篇
  2023年   3篇
  2022年   1篇
  2020年   7篇
  2019年   5篇
  2018年   3篇
  2017年   5篇
  2016年   4篇
  2015年   6篇
  2013年   15篇
  2012年   4篇
  2011年   3篇
  2010年   1篇
  2009年   5篇
  2008年   4篇
  2007年   2篇
  2006年   3篇
  2005年   1篇
  2004年   2篇
  2002年   1篇
  1999年   1篇
  1996年   1篇
排序方式: 共有77条查询结果,搜索用时 31 毫秒
1.
The Hui-style residence is an important architectural heritage of China. The hollow wall structures are widely used to build its exterior wall system. However, the thermal performance of the hollow wall is no longer able to meet the new energy-saving and environmental requirement. This article describes a laboratory study of the development of foamed mortar (FM), with the potential for use in thermal upgrading of the Hui-style hollow wall system without dramatically changing its traditional structure. The key early age, physical, mechanical and thermal properties were systematically measured. Two extended models were respectively developed to calculate compressive strength and thermal conductivity, as a function of porosity. Environment chamber test was also employed to investigate the effectiveness of this novel thermal upgrading approach and the results show that filling the voids with FM can effectively improve the overall thermal resistance of the hollow wall system by 44%, which is almost equal to the overall thermal resistance when using the more expensive commercial inorganic stucco system. In addition, the combination of these two methods yielded an overall thermal resistance of 0.701 m2·K/W, which is even higher than 0.67 m2·K/W for the code required in the hot summer/cold winter climate zone.  相似文献   
2.
The insights of feminist science and technology studies (STS) into the constructed and situated nature of knowledge have proved crucial to informing feminist geography. Since the rise of emotional geographies, feminist methodologies no longer simply reflect on questions of positionality, partiality, and power relations, but also on the role of emotions in the field. In this article, we argue that a feminist STS perspective has much to offer when thinking about the way emotions are engineered, controlled, and negotiated in research processes. Our engagement with what we call ‘social laboratories’ – i.e., spaces in everyday life where (experimental) research is conducted with human beings – advances debates in feminist geography, as these laboratories crystallize the emotional entanglements feminists encounter in the field. Looking at economic experiments in Ghana and fertility clinics in Mexico, we discuss the difficulties of doing feminist fieldwork in these experimental research spaces. We argue that the constant negotiation of emotions and ethics is crucial to access, assess, and do fieldwork in research settings that do not adhere to feminist ideals, but nevertheless have gendered effects on women's and men's lives. Rethinking ‘the place of emotions in research’ (Bondi 2005, in Emotional Geographies, edited by Joyce Davidson, Liz Bondi, and Mick Smith, 231–246, Aldershot: Ashgate) through social laboratories forges instructive links across feminist/emotional geographies and social studies of science.  相似文献   
3.
Indigenous women continue to experience a disproportionately higher burden of cervical cancer than non‐Indigenous women in Australia. The National Indigenous Cervical Screening Project used probabilistic record linkage to combine population‐based administrative databases and identify Indigenous women on Pap Smear Registers. This study aimed to quantify the spatial variation by local government areas (LGAs) for Indigenous and non‐Indigenous women in Queensland in cervical screening participation rates and related outcomes. Empirical Bayes local geostatistical smoothing was performed to reduce the likelihood of spurious variation between small areas. The cohort included 1,091,260 women (2 per cent Indigenous) aged 20 to 69 with 2,393,708 Pap smears between 2006 and 2011. Indigenous women had smoothed LGA‐specific 5‐year participation rates (interquartile range (IQR) 38.9–53.3 per 100 eligible women) consistently lower than non‐Indigenous women (IQR 80.7–85.3). The non‐overlapping confidence intervals of these rates suggest that the Indigenous differential was significant. Compared with Indigenous women, non‐Indigenous women had consistently lower and more stable prevalence rates of histologically confirmed high grade abnormalities (IQR 8.0–10.1 versus 15.0–21.3 per 1,000 screened women). Although the LGA‐specific rates also suggest that a higher proportion of non‐Indigenous women were followed‐up within two months of an abnormal screening result, the wide confidence intervals for these estimates limit our ability to draw definitive conclusions about spatial patterns for this outcome. These findings highlight the importance of continued monitoring and ongoing efforts to identify drivers of these patterns and develop effective strategies to improve participation and potentially reduce the cervical cancer burden among Indigenous women.  相似文献   
4.
The late Stone Age Pitted Ware site at Ajvide, Gotland, in the Baltic Sea, Sweden, has revealed a large deposit of fishbone and approximately 400 bone fishhooks, complete and incomplete. Cod (Gadus morhua), which is one of the most abundant fish species in the bone assemblage, was probably caught with hook and line fishing. To investigate the fishhooks' field of application, a morphological and morphometric study was performed on 384 available hooks. Two sets of replicas made of four selected original fishhooks were submitted to a strength test. A breakage study of the incomplete hooks in comparison with the strength-tested hooks was carried out in order to distinguish fresh breaks from dry breaks. It seems that a certain morphology for fishhooks was preferred at Ajvide, indicating they were produced by skilled craftsmen for special usage. The strength test showed that the hooks had a weight bearing capacity more than the average size of cod caught at Ajvide. Using results of these tests, we predicted that the mean breaking strength of 46 intact Ajvide hooks was 96.6 ± 26.1 (s.d.) Newtons (equivalent to 9.85 ± 2.7 kg). The design of fishhooks changed somewhat over time, being slightly larger in the oldest layers of the site. The breakage patterns of the hooks show that the bow was the most common area of breakage. The design and weight bearing capacity of the hooks point to a specialized cod fishery from boats in deep water.  相似文献   
5.
In the investigation of the dispersal of maize (Zea mays ssp. mays) from south-central Mexico to the northern and southern limits of agriculture in the Western Hemisphere archaeologists and paleoethnobotanists are increasingly turning to the microbotanical record. Recent analysis of phytolith assemblages from charred cooking residues on pottery sherds in central New York recovered using 209 rondel phytolith variables has identified maize as early as 2270 ± 35 B.P. In this article we use discriminant analysis to re-classify these rondel phytolith assemblages resulting in only seven variables. The results are consistent with those achieved earlier using many more variables and a less formal statistical approach in terms of classification and in similarity of the original and reduced data matrix as seen by the Mantel test and cluster analyses.  相似文献   
6.
芮田生  阎洪 《旅游科学》2011,25(3):14-23
对一个地区的旅游竞争力进行评价有助于客观地了解该地区旅游业的发展状况,而科学合理的评价依赖于评价指标和评价方法的选择。本文提出了合理选择指标的原则,并在所构建的旅游竞争力评价指标体系中引入了"软"指标。由于单一评价模型的评价结果各不相同,本文引入组合评价模型对西部十二省、自治区、直辖市的旅游竞争力进行评价,然后采用斯皮尔曼等级相关系数对组合评价结果进行检验,结果显示本文采用的组合评价方法与其它评价方法的一致性最高,说明该方法能比较客观综合地反映旅游竞争力状况。最后,通过聚类分析,进一步验证了本文方法的有效性。  相似文献   
7.
鉴于目前我国在构建价值转移模型中存在的限制因素,本文采用基于Meta分析的价值转移方法并尝试利用国外游憩活动价值评价的实证研究结果,构建基于Meta分析的国际间价值函数转移模型,估算了我国10种游憩活动的日平均消费者剩余.通过将价值转移模型估算的游憩活动价值“转移值”与国内97个游憩价值评价的“真实值”做比较,对价值转移模型的有效性和可靠性进行统计检验,平均转移误差为18.74%.最后,总结了提高我国Meta回归价值转移模型的具体、可操作性方法及途径.  相似文献   
8.
This study shows how control over delicately balanced supply chains from raw material to the final product shifted from one national industry to another. By 1920, Dutch cinchona producers and quinine manufacturers dominated the international cartel that controlled the worldwide production and distribution of quinine (an antimalarial), quinine sulphate (a semi-finished product) and cinchona (the raw material). Twenty years earlier, however, this cartel had been controlled by the German pharmaceutical industry. How can we understand the shift of power in the world’s first pharmaceutical cartel? We argue that the internal shift of power was largely the result of the following three factors: a global industrial laboratory revolution; the vertical integration of a transoceanic network of cinchona producers, quinine manufacturers, (colonial) scientists and state officials across the Dutch Empire; and Germany’s economic isolation during the First World War.  相似文献   
9.
Chuaria is widespread in Late Precambrian deposits throughout the world. In China it has been found in the Jingeryu Formation of Jixian County, Tianjin, and in its equivalents in eastern China including the Nanfen Formation of Liaoning and Jilin Provinces, and the Liulaobei Formation of Anhui Province. In the latter, Chuaria is associated with the genus Tawuia which Hofmann (in Hofmann & Aitken, 1979) described as algae of undertermined affinity and which is based on material from Canada. The glauconitic sandstone directly resting upon Chuaria-bearing greyish-green shale of the Jingeryu Formation in Jixian County has a K-Ar age of 0.899 Ga. This paper describes C. circularis Walcott, T. dalensis Hofmann and T. sinensis n. sp., and discusses the morphology, biological and taxonomic affinities, and age and geographic distribution of Chuaria. Because of the association of Chuaria and Tawuia in the Mackenzie Mountains, Canada, and also in the area of Shouxian County, Anhui Province, China, it is considered that Chuaria and Tawuia probably have close affinities. According to their general morphology and occurrence, both may be marine planktonic multicellular algae.  相似文献   
10.
An experimental study on half-scale brick-masonry models with different strengthening and retrofitting measures has been studied under cyclic loading in a quasi-static test facility. The strengthening measures undertaken for the studies axe the horizontal bond beam at the lintel and sill level with a combination of vertical reinforcement at corners and openings. The retrofitting measures studied are grouting with epoxy-sand-mortar and cement-grout-injection with welded wire mesh in the cracked region. The tests reveal that the horizontal bond beam at lintel level with vertical reinforcement is effective in reducing the cracking above the lintel level. The insertion of an additional sill-band signi-ficantly reduces the cracking in walls. The epoxy-sand-mortar techniques for retrofitting of cracked regions prove to be effective enough to restore the initial strength, stiffness and deformation capacity. Although specimen retrofitted with cement-grout-injection with welded wire mesh is effective to regain the ultimate strength yet the brittle failure is observed as the specimen is stressed beyond the elastic limit.  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