全文获取类型
收费全文 | 5889篇 |
免费 | 229篇 |
国内免费 | 90篇 |
专业分类
测绘学 | 171篇 |
大气科学 | 554篇 |
地球物理 | 1465篇 |
地质学 | 2046篇 |
海洋学 | 564篇 |
天文学 | 759篇 |
综合类 | 22篇 |
自然地理 | 627篇 |
出版年
2021年 | 63篇 |
2020年 | 66篇 |
2019年 | 87篇 |
2018年 | 127篇 |
2017年 | 118篇 |
2016年 | 157篇 |
2015年 | 146篇 |
2014年 | 204篇 |
2013年 | 328篇 |
2012年 | 242篇 |
2011年 | 269篇 |
2010年 | 198篇 |
2009年 | 308篇 |
2008年 | 289篇 |
2007年 | 264篇 |
2006年 | 220篇 |
2005年 | 192篇 |
2004年 | 199篇 |
2003年 | 194篇 |
2002年 | 185篇 |
2001年 | 134篇 |
2000年 | 137篇 |
1999年 | 116篇 |
1998年 | 107篇 |
1997年 | 94篇 |
1996年 | 85篇 |
1995年 | 86篇 |
1994年 | 77篇 |
1993年 | 63篇 |
1992年 | 66篇 |
1991年 | 70篇 |
1990年 | 67篇 |
1989年 | 59篇 |
1988年 | 58篇 |
1987年 | 68篇 |
1986年 | 47篇 |
1985年 | 74篇 |
1984年 | 84篇 |
1983年 | 73篇 |
1982年 | 66篇 |
1981年 | 77篇 |
1980年 | 65篇 |
1979年 | 59篇 |
1978年 | 43篇 |
1977年 | 55篇 |
1976年 | 63篇 |
1975年 | 50篇 |
1974年 | 58篇 |
1973年 | 50篇 |
1972年 | 26篇 |
排序方式: 共有6208条查询结果,搜索用时 15 毫秒
951.
952.
953.
954.
955.
Hans Peter Cornelius 《International Journal of Earth Sciences》1952,40(2):257-261
Ohne Zusammenfassung 相似文献
956.
The records of two large stock and station agents, Loan & Mercantile Agency in Dunedin and Wright Stephenson in Invercargill, allowed us to track the timing, nature, magnitude and rate of landscape change in southern New Zealand between 1896 and 1920. This period extends from the final years of subdivision of large estates, and includes closer settlement, the shift from pastoral farming to intensive agriculture, growth of dairying, and increasing mechanisation of agriculture. These changes are reflected in clients’ annual expenditures on capital items such as fencing and building materials, tools and implements, materials for drains. 相似文献
957.
958.
959.
Johanna?Engstr?mEmail authorView authors OrcID profile Peter?Waylen 《Theoretical and Applied Climatology》2018,131(3-4):1133-1146
The hydroclimatology of the southeastern USA (AL, GA, NC, SC, and TN) is analyzed from a holistic perspective, including multiple climate drivers. Monthly precipitation modeled by the PRISM group and runoff data (1952–2011) from 18 basins are analyzed using a single-field based principal component’s analysis. Results indicate that the Atlantic Multidecadal Oscillation and El Niño-Southern Oscillation are the main atmospheric drivers of hydroclimate variability in the region, sometimes operating at several months’ lag. Their influence is the strongest in the fall through spring, which corresponds with the dry season in the southern parts of the study area thereby increasing pressure on already limited water resources. The Arctic Oscillation, North Atlantic Oscillation, and Pacific-North American patterns vary on shorter-term bases, and also show a significant, but temporally more sporadic influence. Insight is also brought to the ongoing discussion, confirming the disassociation of the Arctic and North Atlantic Oscillation. Findings can be used in water resources forecasting, giving an indication of expected water volumes several months ahead. 相似文献
960.
Avoiding dangerous climate change will require a rapid transition away from fossil fuels. By some estimates, global consumption and production of fossil fuels—particularly coal and oil—will need to end almost entirely within 50 years. Given the scale of such a transition, nations may need to consider policies that constrain growth in fossil fuel supplies in addition to those that reduce demand. Here, we examine the emissions implications of a supply-constraining measure that was rapidly gaining momentum in the United States (US) under the Obama administration: ceasing the issuance of new leases for fossil fuel extraction on federal lands and waters. Such a measure could reduce global carbon dioxide emissions by an estimated 280 million tons annually by 2030, comparable to that of other major climate policies adopted or considered by the Obama administration. Our findings suggest that measures to constrain fossil fuel supply—though not currently viable in a US Trump administration—deserve further consideration at subnational levels in the US or by other countries now, and by future US administrations. 相似文献