全文获取类型
| 收费全文 | 134篇 |
| 免费 | 10篇 |
| 国内免费 | 2篇 |
专业分类
| 测绘学 | 5篇 |
| 地球物理 | 87篇 |
| 地质学 | 22篇 |
| 海洋学 | 15篇 |
| 天文学 | 4篇 |
| 自然地理 | 13篇 |
出版年
| 2022年 | 1篇 |
| 2018年 | 1篇 |
| 2013年 | 1篇 |
| 2012年 | 8篇 |
| 2011年 | 7篇 |
| 2010年 | 3篇 |
| 2009年 | 1篇 |
| 2008年 | 10篇 |
| 2007年 | 6篇 |
| 2006年 | 9篇 |
| 2005年 | 9篇 |
| 2004年 | 1篇 |
| 2003年 | 11篇 |
| 2002年 | 4篇 |
| 2001年 | 6篇 |
| 2000年 | 12篇 |
| 1999年 | 3篇 |
| 1998年 | 6篇 |
| 1997年 | 3篇 |
| 1996年 | 6篇 |
| 1995年 | 6篇 |
| 1994年 | 4篇 |
| 1993年 | 2篇 |
| 1992年 | 4篇 |
| 1991年 | 9篇 |
| 1990年 | 8篇 |
| 1989年 | 3篇 |
| 1981年 | 1篇 |
| 1977年 | 1篇 |
排序方式： 共有146条查询结果，搜索用时 109 毫秒
1.
"While 'closed-door' immigration policies are adopted by most countries, 'exceptionalist' legislation is often made to permit entry of special immigrant groups. An example is the British Nationality (Hong Kong) Act 1990, which was passed in the run-up to the change in sovereignty of Hong Kong in 1997. Britain's increasingly restrictive immigration policies prior to 1990 [have] resulted in the majority of Hong Kong citizens having British nationality (as British Dependent Territories citizens) but without the right of abode in the U.K. The 1990 Act conferred full British citizenship status on 50,000 heads of households in Hong Kong." The authors conclude that "in a world of marked global inequalities, immigration pressure will become even more extreme and is likely to produce an increasing number of cases of exceptionalist immigration legislation in countries with both ?open' and 'closed'-door policies.' 相似文献
2.
4.
5.
7.
长江三角洲南部“大城市圈振兴”理论的质疑 总被引：3，自引：0，他引：3
工业发展和城市化的传统理论，对亚洲的某些具有较高生产力水平，且还在发展中的“大城市圈”不能充分地解释，本文对长江三角洲南部空间经济转为的“大城市圈振兴”理论进行了批判地评论，根据最新的现场调查结果，从根本上对“转为过程”的假说提出质疑，并且提出了更适当的的区域发展战略，此外还证明，关于亚洲大城市带的一般结论，必须建立在对地方性经济变革认识的基础之上。 相似文献
9.
10.
Many invaluable underwater buildings of archaeological interest in Alexandria were discovered in 1996 at different sites in the Eastern Harbour of Alexandria. There is a belief that the best way to protect these invaluable heritages is to transfer them to an underwater park or museum. Obviously, the execution of such a project depends essentially upon the water quality (including water transparency) improving in the future. The harbour is presently polluted by discharge of wastewater effluents from different sources. It has recently been decided to restore this important coastal area through: (1) stopping the direct discharge of wastewater effluents into this semi-enclosed harbour in 1993 and (2) gradually reducing the discharge of the municipal wastewater through marine outfalls at two sites lying at the outer sides of the harbour. Zero discharge is expected to be effective by the end of the year 2001. The present work, therefore, is a follow up of the study of water quality in the harbour after 1993: in 1996 and 1999-2000. The water quality of an open sea reference station was also studied for comparison. The results reveal occurrence of an improvement of the environmental conditions in the harbour. The water has turned from being eutrophic to mesotrophic. The harbour is expected to become meso/oligotrophic as soon as the complete cessation of the discharge from the two outside sources is attained. 相似文献