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   736篇
  免费   22篇
  2024年   4篇
  2023年   13篇
  2022年   9篇
  2021年   14篇
  2020年   22篇
  2019年   36篇
  2018年   19篇
  2017年   31篇
  2016年   34篇
  2015年   24篇
  2014年   27篇
  2013年   93篇
  2012年   37篇
  2011年   37篇
  2010年   27篇
  2009年   26篇
  2008年   31篇
  2007年   45篇
  2006年   43篇
  2005年   36篇
  2004年   21篇
  2003年   31篇
  2002年   24篇
  2001年   20篇
  2000年   21篇
  1999年   5篇
  1998年   4篇
  1997年   1篇
  1996年   3篇
  1995年   1篇
  1994年   4篇
  1993年   3篇
  1991年   2篇
  1989年   1篇
  1988年   1篇
  1984年   1篇
  1983年   4篇
  1982年   2篇
  1978年   1篇
排序方式: 共有758条查询结果,搜索用时 0 毫秒
101.
南阳春秋彭射墓出土兵器中包括有铁援铜戈、铜铍、铜殳、锥形铜镞等少见器物,在同期墓葬中并不常见。其中铁援铜戈的制作工艺与前期同类器物有着一脉相承的工艺技术。出土的铜殳和铜铍皆为春秋时期同类器物中的较早类型,又有所区别,有着地域性特征。圆锥头形铜镞镂空的装饰手法在同类镞中也较为罕见。这些青铜兵器含有较多楚文化风格,但也不乏淮河上游地区文化因素。  相似文献   
102.
浙江瓯海出土一件西周青铜器腐蚀成因研究   总被引:4,自引:3,他引:1  
为研究浙江温州瓯海M24墓出土的一件青铜器的腐蚀成因,采用扫描电镜(SEM)、X射线荧光光谱仪(XRF)、X射线衍射仪(XRD)、离子色谱分析仪(HPIC)等,对青铜剑腐蚀产物及其埋藏土壤进行了分析。结果表明,青铜剑已严重腐蚀,铜元素大量流失形成以锡元素为主的腐蚀产物。通过测量模拟瓯海土壤环境下的自腐蚀电位并参照CuH2O体系的电位-pH图,推导出了浙江瓯海出土一件西周青铜器腐蚀反应历程。研究结果对类似出土文物有参考价值。  相似文献   
103.
ABSTRACT Despite the enormous efforts made to civilize the Hawaiian, the Maori, the Samoan, and Fijian, Islanders have not forgotten all of their stories and in fact many Pacific peoples are in a position to recover much of the knowledge that sustained communities for thousands of years. There is hope in what we have done to reclaim our heritages—finding our voices in our languages, stories, and songs, our perspectives in our arts and literatures, our muscle and will in our own political advocacy and pursuit of our rights in courts and international arenas. There is need, however, for a new vision that reunites human beings with all of their relations in the world, a vision necessary to sustain a very difficult struggle.  相似文献   
104.
Becky Mansfield 《对极》2011,43(2):413-434
Abstract: This paper contributes to scholarship on health and environment by focusing on connections between human health and political economy of seafood. The contemporary rise of aquaculture is an effort on the part of the seafood industry to escape the contradictions of capital that create crisis in capture fisheries. Yet intensive aquaculture may also create human health problems that contribute to new crises. Aquaculture practices not only increase production of healthful fish, but also lead to fish burdened with chemical pollutants about which there are a variety of health concerns. These health concerns pose problems for producers who may not be able to sell contaminated seafood. By examining the intertwined biochemical and social processes that produce multiple natures (fish bodies, human bodies and the aquatic environment), the paper shows that concerns about health are not only an outcome of political economic processes, but are also an explanatory factor in these processes.  相似文献   
105.
文物古迹是过去文化的载体,文化既是不同人们共同体在特定时空中适应环境与社会的结晶,也是人类曾经的生存可能性的记录,因此,文化遗产是发展的智慧资源而非包袱。改革开放以来我们对文物与文化遗产及其价值的认识有一个不断拓展和提高的过程,经历了由古玩、文物到全民性的文化遗产自觉的演变。正确认识和处理不同文化及历史文化遗产,既是作为文明古国的中国发展过程中无法避开的选择,也是全球化、信息化时代古今中外文化大会面时代人类和谐共处、共同繁荣的前提性要求。  相似文献   
106.
The past three decades have seen the resurgence of China's civil society through the blossoming of NGOs that campaign for various marginalised interests, including environmental protection. Many studies have examined the co-evolution of the Internet and China's civil society. This paper examines the role of the Internet in strengthening grassroots environmental activism, taking into consideration the corporatised character of Chinese NGOs. Through a detailed ethnographic case study of a leading grassroots environmental group, the Global Village of Beijing (GVB), I argue that Internet technologies effectively empower resource-poor activists in their self-representation, information brokering, network building, public mobilisation and construction of discourse communities. The Net therefore contributes to the nascent formation of a green public sphere in China by fostering a discourse that counterbalances rapid economic development. Also discussed here are issues that hamper this process, including resource limitations, the fragmentation of online discourse communities, and the marginalisation and “caging” of environmental discourse.  相似文献   
107.
108.
S. L. POTTER  M. A. CHAN 《Geofluids》2011,11(2):184-198
The Jurassic Navajo Sandstone of Grand Staircase Escalante National Monument (GSENM), Utah, exhibits a broad range of iron oxide/oxyhydroxide concretionary geometries that record a complex paragenetic history of the reservoir. The concretionary geometries are as follows: (i) common macroconcretions (>5 mm in diameter), (ii) ubiquitous microconcretions (<5 mm in diameter), (iii) localized iron oxide/oxyhydroxide‐lined northeast‐striking joints, and (iv) loopy asymmetrical mineralization and banded precipitation patterns (Liesegang bands) associated with the joints. Spheroidal concretion geometries typically indicate diffusive mass transfer, whereas asymmetrical mineralization represents advective directional flow. Liesegang bands parallel to asymmetrical mineralization denote a diffusive mass transfer component perpendicular to the principal flow direction. Careful study of concretionary geometries and their cross‐cutting relationships establishes a relative timing of precipitation and mobilization events. Macroconcretions formed post‐Laramide (<55 Ma), prior to and independent of the Miocene joints. The joints provided conduits for later oxidizing fluids that precipitated iron oxide/oxyhydroxide lining on the joint faces. Advective mass transfer overprinted the area with preferentially cemented flow lines (asymmetrical mineralization) less than 10 Ma, coincident with development of a hydraulic low to the southeast of the region (Colorado River downcutting). Certain trace elements are genetically tied to concretion formation, and evaluation of trace elements establishes precursor mineral phases. Enriched uranium concentrations in concretions (relative to the host rock) and low/undetectable sulfur concentrations in both host rock and concretions suggest that iron oxyhydroxide was a primary precipitate rather than a reduced iron mineral (i.e., pyrite or siderite) that later oxidized. Enrichment of Ni and As in concretions functions as fingerprints for diagenetic concretion formation when determining genesis of ambiguous iron oxide/oxyhydroxide spherules such as the remotely sensed ‘blueberries’ on Mars. Similarities between Mars and Utah spherules such as geometry, in situ spacing and volumetric density suggest that Mars spherules precipitated via a geochemically self‐organized nucleation pattern in diffusive chemical reaction fronts.  相似文献   
109.
ABSTRACT. Discussions of globalisation and identity have focused on the renewed relevance of various post‐national frameworks of belonging, including the Muslim umma. This article argues against the idea that the umma has come to constitute a primary referent in contemporary Muslim debates about identity or a form of globalised political consciousness. Furthermore, the advent of ‘post‐Islamism’ means that Islamic political mobilisation rarely seeks to establish alternative political orders within the container of the nation‐state. However, this does not mean that we are seeing a reaffirmation of the nation in Muslim contexts today. Rather, transnational Muslim solidarities represent an intermediate space of affiliation and socio‐political mobilisation that exists alongside and in an ambivalent relationship with the nation‐state. I point to two different socio‐religious movements that, without positing the primacy or exclusivity of the umma/Islamic identity, express discrepant visions of the relationship between Islam and the nation: (1) the Fethullah Gülen movement, which serves simultaneously as the vehicle for a particular vision of neo‐Ottoman Turkish nationalism and a critique of the Kemalist national order; and (2) the neo‐Salafist movement, read here as an effort to embed conceptions of public morality and accountability within the discursive tradition of orthodox Islam rather than the institutional framework of modern polity.  相似文献   
110.
The present paper explores the potentials of trace elements in human dental enamel to indicate mobility and to detect the presence of individuals who had migrated into a community after childhood. Three Pre-Hispanic samples of infants from the Yucatán peninsula were chosen, one from the northern coast (Xcambó), one from the coast of the Gulf of Mexico (Campeche) and the last one from the tropical inland rain forest (Calakmul). Infants’ first permanent molars are the term of reference because infants were very likely born in the same place where they died and therefore are supposed to represent the local geo-chemical environment. Their chemical signature was then compared to the one of the adults from the site of Xcambó. The elemental composition was recorded by means of laser ablation-time of flight-ICP-MS. Sr and Ba (and secondly Mg and I) discriminate well the three infant samples. All the Early Classic adults from Xcambó fall within the range of variation of the site’s infants, while 25% of the Late Classic adults fall outside the range in agreement with archaeological, bioarcheological, and isotopic evidence. LA-ICP-Ms analyses of trace elements in archaeological samples can be an important analytical tool to detect foreigners in local populations. The selection of infants as reference values helps reduce the limits faced by trace element analyses in past human populations studies.  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