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   4619篇
  免费   208篇
  2023年   27篇
  2021年   20篇
  2020年   60篇
  2019年   103篇
  2018年   137篇
  2017年   170篇
  2016年   168篇
  2015年   116篇
  2014年   112篇
  2013年   1409篇
  2012年   134篇
  2011年   131篇
  2010年   152篇
  2009年   146篇
  2008年   110篇
  2007年   110篇
  2006年   105篇
  2005年   69篇
  2004年   63篇
  2003年   70篇
  2002年   68篇
  2001年   66篇
  2000年   60篇
  1999年   58篇
  1998年   46篇
  1997年   57篇
  1996年   37篇
  1995年   43篇
  1994年   38篇
  1993年   42篇
  1992年   44篇
  1991年   47篇
  1990年   26篇
  1989年   21篇
  1988年   38篇
  1987年   37篇
  1986年   38篇
  1985年   49篇
  1984年   42篇
  1983年   56篇
  1982年   48篇
  1981年   45篇
  1980年   33篇
  1979年   42篇
  1978年   38篇
  1977年   31篇
  1976年   37篇
  1975年   30篇
  1974年   25篇
  1973年   20篇
排序方式: 共有4827条查询结果,搜索用时 62 毫秒
71.
72.
73.
Many parts of the world are threatened with environmental damage and degradation, affecting both the natural resources and the economy of the area. This article analyses the factors affecting the likelihood of different environmental policy reforms in Latin America, with particular emphasis on: the strengths and weaknesses of different groups which promote such reforms; the degree to which the reforms are compatible with the region's current economic policies; and how the type of political regime affects these issues. It reaches the conclusion that, although there has been progress in recent years, the possibility of carrying out far-reaching reforms which could substantially reduce pollution and resource depletion has been limited by: 1) the difficulties involved in linking environmental issues with concerns for social justice; 2) economic policies which promote the exploitation of natural resources and labour and weaken the public sector; and 3) the great influence over regional governments of groups with vested interests in continuing environmentally destructive activities.  相似文献   
74.
75.
This study examined landcover change during 1940–1988 in two contiguous landscapes of approximately 12,400 hectares in central Ohio, USA: an inertial till plain area and a more dynamic moraine area. Agriculture dominated both landscapes throughout, however, the cover of natural vegetation and urban-suburban development increased over time on the moraine while natural vegetation decreased and agriculture increased on the till plain. Markov process models for landcover change were constructed for three 14–17-year time intervals and for the entire forty-eight-year study period. Probabilities of self-replacement for agricultural lands (0.91–0.97) were higher and those for forests (0.54–0.65) lower than those reported for other landscapes. Predictions of landcover percentages for fifty years in the future were made using Markov process models derived from actual cover changes in 1940–1957, 1971–1988, and 1940–1988. All three models produced similar predictions for the inertial till plain area. In contrast, the three models' predictions differed considerably for the moraine area. Only the 1971–1988 transition matrix was sensitive to increases in urbanization and reforestation which began on the moraine in the 1970s. These results indicate that reliance on lengthy study intervals and net rates of change can obscure spatial and temporal patterns of landcover change that are caused by natural and socioeconomic factors operating on shorter time scales.  相似文献   
76.
The concept of sustainability has become a significant consideration in planning in Europe and the US. At both the international and the national level, urban planners and policymakers have developed a package of policies designed to produce sustainable growth and development. In transport, this has been interpreted to mean that we need to increase accessibility while we reduce mobility by shifting trips from automobile to walking, bicycle or public transport modes. Using this criteria, the latest Dublin transport plan has been found to be only partially effective. Similar to many American transport plans, the DTI has opted for the infrastructure‐related sustainability policies and avoided the less popular economic disincentives.  相似文献   
77.
Book Reviews     
Ken Booth and Steve Smith (eds), International Relations Theory Today, Cambridge: Polity Press, 1995. xii + 367pp. $39.95 (paper).

Christine Sylvester, Feminist Theory and International Relations in a Postmodern Era. Cambridge: Cambridge University Press, 1994. xi + 265pp. $47.50 (paper).

Stephanie Lawson (ed.), The New Agenda for Global Security: Cooperating for Peace and Beyond. St. Leonards: Allen & Unwin/Department of International Relations, RSPAS, Australian National University, 1995. xi + 217pp. $24.95.

Anne O. Krueger, Economic Policies at Cross‐Purposes: The United States and Developing Countries. Washington, DC: Brookings Institution, 1993. xii + 253pp. $US36.95 (cloth).

Robert L. Paarlberg, Leadership Abroad Begins at Home: U.S. Foreign Economic Policy After the Cold War. Washington, DC: Brookings Institution, 1995. xxv + 115pp. $US28.95 (cloth); $US10.95 (paper).

Tony Brenton, The Greening of Machiavelli: The Evolution of International Environmental Politics. London: Royal Institute of International Affairs/Earthscan, 1994. xvii + 282pp. $UK14.95 (paper).

John Charmley, Churchill's Grand Alliance: The Anglo‐American Special Relationship, 1940–1957. London: Hodder & Stoughton, 1995. xv + 427pp. $55.00 (cloth).

Victor A. Kremenyuk, Conflicts In and Around Russia. Nation‐Building in Difficult Times. Westport: Greenwood Press, 1994. xiv + 159pp. $US49.95 (cloth).

Alexander Johnston, Sipho Shezi and Gavin Bradshaw (eds), Constitution‐making in the New South Africa. London and New York: Leicester University Press, 1993. viii + 272pp. $UK 39.50.

Ramesh Thakur, The Politics and Economics of India's Foreign Policy. London: Hurst and Company; New York: St. Martin's Press, 1994. xi + 306pp. No price given.

Francis Seow, To Catch a Tartar: A Dissident in Lee Kuan Yew's Prison (with a foreword by C.V. Devan Nair). Yale Southeast Asia Studies Monograph 42, New Haven: Yale Centre for International and Area Studies, 1994. xxxiii + 293pp. $50.00 (paper).

Brij Lal, Robert Kiste and Kerry Howe (eds), The Tides of History: The Pacific Islands in the 20th Century. St Leonards: Allen & Unwin, 1994. xviii + 475pp. $34.95 (paper).

LaMond Tullis, Unintended Consequences—Illegal Drugs and Drug Policies in Nine Countries. Boulder, CO: Lynne Rienner, 1995. ix + 229pp. $US42.00 (cloth).

The United Nations and Cambodia 1991–1995, The United Nations Blue Books Series, Vol. II. New York: Department of Public Information, United Nations, 1995. 352pp. $US29.95 (paper).

‘Atu Emberson‐Bain (ed.), Sustainable Development or Malignant Growth? Perspectives of Pacific Island Women. Suva, Fiji: Marama Publications, 1994. 290pp. No price given.

Payam Akhavan and Robert Howse (eds), Yugoslavia, the Former and Future: Reflections by Scholars front the Region. Washington, DC and Geneva: The Brookings Institution and The United Nations Research Institute for Social Development, 1995. xxviii + 188pp. $US32.95 (cloth) $US 12.95 (paper).

David Camroux, ‘Looking East’ . . . and Inwards: Internal Factors in Malaysian Foreign Relations during the Mahathir Era 1981–1994. Australia‐Asia Papers No. 72. Griffith University: Centre for the Study of Australia‐Asia Relations, 1994. iii + 62pp. $10.00.  相似文献   

78.
The ecologically sustainable development (ESD) process represented a significant attempt by the Commonwealth Government to involve pro-environment and pro-development protagonists in a major environmental consultative forum. The government's inclusion of peak interest organisations into an exclusive consultation process resembles a neo-corporatist approach to interest intermediation. However, neo-corporatist theory has been applied almost exclusively to economic policy areas and interest organisations representing capital, labour and the state. Analysing the involvement of select environmental organisations in the ESD process, this paper argues that neo-corporatist theory can be extended to include non-production-based interest organisations. The implications of environmental organisation participation in a neo-corporatist structure are examined, including a discussion of the tension between neo-corporatist and new social movement theories.  相似文献   
79.
Some 630 Roman silver coins excavated at Augusta Raurica (Switzerland) have been analysed by non-destructive X-ray fluorescence and X-ray diffraction. Furthermore, the density and the weight have been determined. The measured average density of plated and massive depletion-silvered coins is lower than the density calculated from the chemical composition, whereas massive coins display equal values for both of the densities. Based on experimental X-ray investigations of modern silver (tempering, acid treatment, production of corrosion layers), the nature of corrosion products on silver, their impact on surface analysis, and aspects of wearing-off by circulation are briefly discussed.  相似文献   
80.
SPATIAL DEPENDENCY OF SEGREGATION INDICES   总被引:3,自引:0,他引:3  
A few researchers have mentioned the scale sensitivity of segregation index, D. In this paper, I discuss analytically and empirically why using large enumeration areal units usually results in low segregation measures, and using small areal units produces relatively high segregation measures. The discussion is also applicable to the multi-group variant of D. A major finding is that if people of the same ethnic groups are positively spatially auto-correlated, increasing the size of areal units of analysis may not lower D initially, because only people of the same group are added. But enlarging the areal units subsequently may include population of other ethnic groups, and therefore could lower D. However, if the boundaries of the larger enumeration units are drawn to include only population of the same group, then D will not change significantly. Both the spatial autocorrelation of ethnic group population and zonal pattern are critical factors in determining the scale sensitivity of D.  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