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   1260篇
  免费   298篇
  2021年   15篇
  2020年   13篇
  2019年   100篇
  2018年   69篇
  2017年   67篇
  2016年   122篇
  2015年   82篇
  2014年   83篇
  2013年   261篇
  2012年   85篇
  2011年   93篇
  2010年   70篇
  2009年   48篇
  2008年   66篇
  2007年   65篇
  2006年   44篇
  2005年   19篇
  2004年   35篇
  2003年   29篇
  2002年   20篇
  2001年   21篇
  2000年   29篇
  1999年   3篇
  1998年   14篇
  1997年   17篇
  1996年   12篇
  1995年   14篇
  1994年   11篇
  1993年   3篇
  1992年   4篇
  1991年   2篇
  1990年   2篇
  1989年   2篇
  1987年   5篇
  1986年   2篇
  1985年   3篇
  1984年   1篇
  1983年   1篇
  1982年   4篇
  1980年   3篇
  1979年   2篇
  1978年   1篇
  1977年   6篇
  1976年   2篇
  1975年   1篇
  1974年   2篇
  1971年   1篇
  1969年   1篇
  1968年   1篇
  1951年   1篇
排序方式: 共有1558条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
995.
996.
The transatlantic partnership needs to be reassessed. Since the end of the Cold War, Europe has chosen to bandwagon with the United States and to outsource its security to Washington. Bandwagoning has serious consequences when the use of force is at stake: it may lead to entrapment, where weaker allies may be involuntarily dragged into a conflict. It may also lead to abandonment, where the dominant ally may choose to discard their vital security concerns. With the evolution of the international system towards a multipolar configuration, this strategy of bandwagoning is becoming increasingly costly for Europe while the dominant power, the United States, is progressively confronted by other competitors at the systemic level. These classic dilemmas attached to an asymmetric partnership are exacerbated in a multipolar configuration. In particular, the abandonment scenario may become more and more frequent precisely because there is competition—and thus potential costs—at the international level: the United States may leave Europe alone, not by choice but by necessity. The current crisis in Ukraine illustrates this shift: while some American leaders were keen to escalate the conflict by arming Ukraine, the Obama administration's commitment to the defence of Europe has been minimal and it has largely delegated the management of the crisis to the Europeans themselves. Washington had other and more important priorities. Strategic autonomy is not an option for Europe; it has become a reality, a Gaullist moment where Europeans will have to learn to think and act strategically for themselves.  相似文献   
997.
Between 1952 and 1970, Gamal Abdel Nasser and Egypt's Free Officers Movement established the paradigmatic pan‐Arabist revolution from above. Yet it has become something of a cliché to maintain that the Free Officers had no blueprint of action before seizing power and that they later instrumentalised pan‐Arabism in their foreign policy, thinly veiling their actual commitments to Egyptian nationalism and imperialism. By contrast, this contribution underlines the impact of the British colonial context on the Free Officers' political formation and their early identification with pan‐Arabism in turn. Drawing on pamphlets, speeches, media output and memoirs, it shows that the Free Officers developed a distinctive form of anticolonial nationalism that emphasised social justice and invoked overlapping Egyptian and Arab identities. Their aspirations for liberation thus entailed a connected foreign policy and nation building programme in which pan‐Arabism was a prime – and early – component.  相似文献   
998.
999.
It has long been recognized that ships built according to the Nordic clinker tradition during the Viking Age were conceived and constructed simultaneously by eye, in a shell‐first manner, and using rules‐of‐thumb to control both the longitudinal and transversal shape of the hull. While a lot of attention has been paid to the conceptual definition of the keel and stems, far less research has explored how such rules would have worked while planking the hull. Two cargo‐ships, Skuldelev 3 and Skuldelev 1, are used to argue for pre‐design and the use of mental templates. This highlights a cognitive dimension of practical knowledge, in particular how it was accumulated, stored and transmitted.  相似文献   
1000.
Intensively used and managed remnants of native vegetation in cities can have characteristics that result as much from ecological gardening as processes independent of humans. We test the degree to which the changes in vegetation of the Bayside Reserve, Melbourne, are consistent with the outcome we would expect from an ecologically gardened nature and to what degree they reflect ongoing processes of exotic invasion and synthetic vegetation dynamics. We compared species lists from 1911, 1971 and 2013 and sample area data from 1971 and 2013. The flora became richer and more exotic, although some native plant species lost in 1971 had been reintroduced to the reserve in 2013. Between 1971 and 2013, the vegetation increased in cover, shrub and tree density, sample areas species richness, and nativeness, the latter two results being inconsistent with the usual patterns of increasing exoticness and decline in species richness with shrub and tree encroachment. These variations from normality were likely to have resulted from the impacts of planting of natives and weeding of exotics, activity that has created combinations of species that probably never occurred in pre‐European vegetation. Although it might not be possible to return to pre‐European ecosystems within this vegetation remnant, the gardened approximation helps some locally uncommon species survive and may make people more sympathetic to nature conservation as a whole.  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