全文获取类型
收费全文 | 4497篇 |
免费 | 176篇 |
出版年
2020年 | 62篇 |
2019年 | 89篇 |
2018年 | 124篇 |
2017年 | 135篇 |
2016年 | 140篇 |
2015年 | 90篇 |
2014年 | 107篇 |
2013年 | 1393篇 |
2012年 | 102篇 |
2011年 | 135篇 |
2010年 | 105篇 |
2009年 | 107篇 |
2008年 | 97篇 |
2007年 | 78篇 |
2006年 | 73篇 |
2005年 | 65篇 |
2004年 | 64篇 |
2003年 | 57篇 |
2002年 | 60篇 |
2001年 | 59篇 |
2000年 | 73篇 |
1999年 | 54篇 |
1998年 | 58篇 |
1997年 | 52篇 |
1996年 | 49篇 |
1995年 | 45篇 |
1994年 | 40篇 |
1993年 | 36篇 |
1992年 | 30篇 |
1991年 | 41篇 |
1990年 | 33篇 |
1989年 | 37篇 |
1988年 | 35篇 |
1987年 | 39篇 |
1986年 | 48篇 |
1985年 | 55篇 |
1984年 | 52篇 |
1983年 | 54篇 |
1982年 | 46篇 |
1981年 | 48篇 |
1980年 | 50篇 |
1979年 | 51篇 |
1978年 | 44篇 |
1977年 | 44篇 |
1976年 | 45篇 |
1975年 | 34篇 |
1974年 | 30篇 |
1973年 | 34篇 |
1972年 | 30篇 |
1969年 | 26篇 |
排序方式: 共有4673条查询结果,搜索用时 31 毫秒
71.
72.
73.
74.
75.
76.
Geological processes are fundamental to the understanding of Global Change and the geological record provides a baseline against which to assess the nature and significance of contemporary global change (Price 1986) 相似文献
77.
78.
Peter H. Sand 《政策研究杂志》1991,19(2):93-102
On March 11, 1989, twenty-four governments called for the development, within the framework of the United Nations, of
new institutional authority, either by strengthening existing institutions or by creating a new institution which, in the context of the preservation of the earth's atmosphere, shall be responsible for combating any further global warming of the atmosphere. (Declaration of The Hague, 1989. p. 1308) 相似文献
new institutional authority, either by strengthening existing institutions or by creating a new institution which, in the context of the preservation of the earth's atmosphere, shall be responsible for combating any further global warming of the atmosphere. (Declaration of The Hague, 1989. p. 1308) 相似文献
79.
80.
Peter Gould 《The Canadian geographer》1991,35(4):324-332
Compared to the geographic wasteland south of your border, geography appears to have fared well in Canada, both as a formal discipline extending our understanding by illuminating the human and physical worlds, and as a subject taught at all levels to create informed and aware citizens. I known you think much remains to be done, and perhaps things always look a bit greener on the other side of the hill, but I hope you will not mind my somewhat envious gaze. In fact, when I received the five volumes of the 'curriculum guideline' for geography, issued by the Ontario Ministry of Education for the intermediate and senior divisions of your high schools (ome 1988), my feelings were not so much envy as panic, a panic that rapidly induced something close to intellectual paralysis. Because in a moment I can only describe now as utterly weak and foolish, I started to read them, only to learn that your senior students 'analyze, interpret … explain … design and develop networks, systems and simulations that involve six or more variables' (ome 1988, A12).
In retrospect, I still think my panic was justified. After 30 years of hard post-doctoral work I have reached the point where I can think about the interactions of maybe three variables, but hardly the combinatorial possibilities of six. Such ineptness would mean that I might just squeeze into your tenth grade and from there slowly work my way over the next two years towards those Olympian heights of analytical thought where dwell Ontario's high school graduates. 相似文献
In retrospect, I still think my panic was justified. After 30 years of hard post-doctoral work I have reached the point where I can think about the interactions of maybe three variables, but hardly the combinatorial possibilities of six. Such ineptness would mean that I might just squeeze into your tenth grade and from there slowly work my way over the next two years towards those Olympian heights of analytical thought where dwell Ontario's high school graduates. 相似文献