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   2899篇
  免费   145篇
  2023年   18篇
  2021年   12篇
  2020年   46篇
  2019年   77篇
  2018年   95篇
  2017年   135篇
  2016年   110篇
  2015年   85篇
  2014年   79篇
  2013年   902篇
  2012年   68篇
  2011年   64篇
  2010年   96篇
  2009年   84篇
  2008年   69篇
  2007年   54篇
  2006年   54篇
  2005年   46篇
  2004年   47篇
  2003年   55篇
  2002年   54篇
  2001年   46篇
  2000年   45篇
  1999年   32篇
  1998年   36篇
  1997年   43篇
  1996年   22篇
  1995年   27篇
  1994年   27篇
  1993年   23篇
  1992年   29篇
  1991年   27篇
  1990年   19篇
  1989年   11篇
  1988年   24篇
  1987年   19篇
  1986年   16篇
  1985年   33篇
  1984年   26篇
  1983年   37篇
  1982年   27篇
  1981年   28篇
  1980年   19篇
  1979年   27篇
  1978年   24篇
  1977年   18篇
  1976年   23篇
  1975年   15篇
  1974年   20篇
  1973年   9篇
排序方式: 共有3044条查询结果,搜索用时 15 毫秒
991.
I would hope that the nations of the world might say that we had built a lasting peace, based not on weapons of war but on international policies which reflect our own most precious values. These are not just my goals, and they will not be my accomplishments, but the affirmation of our nation's continuing moral strength and our belief in an undiminished, ever-expanding American dream. 1
President Jimmy Carter, Inaugural Address, 20 January 20, 1977  相似文献   
992.
Innovation is currently seen as a process which results from various interactions among different actors. Recent theories of innovation emphasize clusters and geographical proximity as loci of knowledge, development and exchange, critical to higher levels of innovation and regional growth. As a consequence, there is a territorial dimension to innovation. This article investigates the innovation activities and networking of 53 small and medium sized enterprises (SMEs) in Ottawa, Canada. Taking its point of departure from the proliferating literature on the localized nature of innovation processes, the article sets out to answer three empirical questions: How intensively are SMEs engaging in innovation activities? To what extent do they interact during innovation process activities? What is the relevance of spatial proximity in networking, and what is the relative importance of localized cooperation as compared to non‐localized cooperation. The results revealed SMEs rely as much on external networks of customers and suppliers, as they do on ones based in their own region, and that these are considerably more important, than other potential sources of ideas, to the innovation process within the firm.  相似文献   
993.
994.
995.
By offering an apology of Japan's closed country policy, Engelbert Kaempfer (1651–1716) was contributing not so much to the literature of exotic journey record, but rather to the field of European political and moral theory, and importantly to the debate over the relative merits of ancient and modern societies and effects of international commerce. There is a marked lack of scholarly attention given to Kaempfer as a modestly interesting political theorist, compared to a substantial body of research praising his record as a scientifically minded observer of remote cultures. As a deceptively straightforward specimen of the genre of travelogue, and also because it has tended to be treated mostly as a pioneering attempt in western Japanese studies, Kaempfer's work has not generally been considered in its relation to the debate on Europe's own moral and political predicament. When it has, the emphasis tended to be on the influence his work exercised on the enlightened European mind and its awareness of alien cultures, rather than on the extent to which the moral and political questions he sought to answer regarding Japan's situation were in fact standard questions formulated within the wider European debate on commerce and government. This paper hopes to correct the imbalance by placing Kaempfer's argument into the context of such contrasting contemporaneous positions as those represented, respectively, by Joseph Addison's view of global commerce in The Spectator and by François Fénelon's vision of the ideal commonwealth of Salente in his Aventures de Télemaque.  相似文献   
996.
I argue that despite the various ways in which Fichte separates right from morality in his 1796/97 Foundations of Natural Right, he nevertheless suggests in the writings from the period of his professorship at the University of Jena that there is a reciprocal relation between them. This requires, however, reading the Foundations of Natural Right in the light of The System of Ethics, which was published in 1798, especially the account of the ethical duties deriving from a person's membership of a profession that Fichte gives in this work. Although this approach allows us to attribute to Fichte a different conception of the state to the amoral one found in the Foundations of Natural Right, I argue that the separation of right from morality developed in this work remains valid and amounts to one of Fichte's main achievements, namely, his identification of the different dispositions that may characterize an individual's relation to the society in which he or she lives. This point is developed by comparing Fichte's amoral conception of the state to Hegel's account of civil society as the ‘state of necessity’. This does not involve an attempt to turn Fichte into Hegel but to show how the insights contained in Fichte's distinction between right and morality can be illuminated with reference to Hegel's theory of civil society and can be retained in the face of a powerful criticism that Hegel makes of the kind of contract theory of the state offered by Fichte.  相似文献   
997.
998.
By examining the case of James MacQueen (1778–1870), this paper initiates a research agenda that contributes to what David N. Livingstone has argued remains the most pressing task for historians of geography: to write ‘the historical geography of geography’. Born in Scotland in 1778, MacQueen was one of the many ‘arm-chair’ geographers whose efforts at synthesising contemporary and historical sources were a significant feature of the encounter between Europe and the rest of the world. Indeed, although he never visited Africa, his speculations about the course and termination of the River Niger turned out to be broadly correct. What makes MacQueen a particularly significant figure was the original source of his theory: enslaved Africans in a Caribbean plantation-colony. In this light, a remark that MacQueen's imagination was ‘taken captive by the mystery of the Great River’ carries a dark double-meaning, because ‘captive’ knowledge was the very source of MacQueen's interest in African geography. Beginning with MacQueen's time in Grenada, the paper explores a series of personal relations, textual traces and West African ethno-histories to reveal how his geographical knowledge and expertise were bound up with Atlantic slavery. This shows not only how the colonial economy, centred on the Caribbean, underwrote the production of geographical knowledge about Africa, but also how British geographical discourse and practice might be probed for traces of Atlantic slavery and enslaved African lives. More generally, the case of James MacQueen illuminates a broader field of relationships between Atlantic slavery, West African exploration, and the development of modern British geography in the late eighteenth and first half of the nineteenth centuries. Examining these relationships is key to writing a ‘historical geography of British geography and Atlantic slavery’ and contributes to postcolonial histories of the discipline by revealing the tangled relationships that bound geography and slavery, knowledge and subjugation, that which ‘captivates’ and those held ‘captive’.  相似文献   
999.
Tikal, a major lowland Maya civic-ceremonial center in the heart of the Petén region of Central America, relied heavily on the adjacent lowland rainforest as a resource base for fuel and construction materials. In this study, we analyzed 135 wood samples from timbers used in the construction of all six of the city's major temples as well as two major palaces to determine which tree species were being exploited and to better understand ancient Maya agroforestry practices during the Late Classic period. We found evidence for a change in preference from the large-growing, upland forest species, Manilkara zapota, to a seasonal wetland species Haematoxylon campechianum in A.D. 741 as well as a decrease in lintel beam widths over time. Though M. zapota later returned as the wood species of choice in A.D. 810, beam widths were found to be significantly smaller. These findings concur with models that hypothesize widespread deforestation during the Late Classic period and indicate a declining forest resource base by the 9th century A.D. Because of the many large timbers available for temple construction in the 8th century, some system of forest conservation is indicated for the ancient Maya prior to the Late Classic period.  相似文献   
1000.
Natural, technical and social factors led to the use of a wide range of rocks for the production of macrolithic artifacts during the later prehistory. In the case of some artifact types, such as the grinding stones, rocks with very different petrographic qualities appear. Analysis of the material behavior, as developed by material sciences, provides a tool which allows the translation of these petrographic characteristics into mechanical properties. Experiments with a group of rocks subjected to different forms of abrasion in industrial machines allow an evaluation of the adjustment between the mechanical properties of the rock and the functions for which they were chosen by prehistoric societies. Finally, the understanding of the mechanical properties of the raw materials together with their forms of exploitation, distribution and use allows the designation of social and economic meaning to the production systems linked to the macrolithic tools.  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