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821.
中国北方有大面积的土地被沙漠和黄土覆盖,是现代沉积和侵蚀比较活跃的地区。强烈的地表过程不仅影响着区域的生产生活活动,还通过粉尘传输影响北半球甚至于更大范围的气候和环境。长期以来,由于综合研究不够,对沙漠-黄土体系的沉积和侵蚀规律以及未来趋向的认识有限。结合对沙漠沙地-黄土沉积的高密度光释光年代测试结果,基于地统计法和遥感分析的黄土堆积量估算以及现代降尘、地表侵蚀的观察研究,认为沙漠沙地-黄土堆积区的沉积和侵蚀过程受气候变化控制,这里既是堆积区,又是侵蚀区,处于动态变化过程中;黄土比沙地沉积保存着更完整的过去气候变化信息。黄土高原水蚀和风蚀在地质历史时期就存在,人类活动加强了侵蚀过程,但可能还没有实质性地改变这一趋向。通过对地质记录和古气候模拟结果的分析,在未来全球变暖的背景下,沙地地区可能由于有效湿度减少变干而使风尘活动加强,黄土高原地区的粉尘沉积速率也将随之加快。 相似文献
822.
从GIS数据的模糊可靠性分析、GIS软件模糊可靠性分析、GIS硬件模糊可靠性分析和GIS人员模糊可靠性分析等4方面阐述GIS的模糊可靠性分析中的关键问题,论述各个关键问题所研究的现状以及面临的困难,提出了解决的方法。 相似文献
823.
824.
The change of annual stream flow in the Shiyang river basin, a typical arid‐inland basin in north‐west China, was investigated using hydrological, meteorological and water‐related human activities' data of the past 50 years. The long‐term trends of the hydrological time series were examined by non‐parametric techniques, including the Pettitt and Mann–Kendall tests. Double cumulative curves and multi‐regression methods were used to separate and quantify the effects of climate changes and human activities on the stream flows. The results show that the study area has been experiencing a significant upward warming trend since 1986 and precipitation shows a decreasing trend in the mountainous region but an increasing trend in the plains region. All stream flows in the upper reach and lower reaches of the Shiyang river exhibit decreasing tendencies. Since 1970, human activities, such as irrigation, have had a significant effect on the upstream flow, and account for 60% of total flow decreases in the 1970s. However, climate changes are the main reason for the observed flow decreases in the 1980s and 1990s, with contributions to total flow decrease of 68% and 63%, respectively. Before 1975, flow decreases in the upper reaches were the main factor causing reduced flows in the lower reaches of the Shiyang river. After 1975, the effect of human activities became more pronounced, with contributions of 63%, 68% and 56% to total flow decreases in the lower reaches of the Shiyang river in the periods 1975 to 1980, 1980s and 1990s, respectively. As a result, climate change is responsible for a large proportion of the flow decreases in the upstream section of the catchment during the 1980s and 1990s, while human activities have caused flow decreases downstream during the same period. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
825.
本文以苏州市吴江区为例,利用1971—2016年吴江区常规气象观测资料、2004—2016年吴江区自动气象观测数据、2016年吴江区各镇人口和面积数据、2016年ASTER GDEM 高程数据和Landsat 8 OLI_TIRS卫星遥感数据,将湖陆风指数引入人居自然环境适宜性评价体系,建立缓冲区后,分别计算气候适宜性指数、地被指数、水文指数、湖陆风指数和人居环境自然适宜性综合指数,在此基础上,分区分级评价了吴江区人居环境的自然适宜性。研究结果表明:(1)吴江区人居环境自然适宜度从西部往东部逐渐递减。(2)一般适宜区主要位于吴江区的东北部和东南局地,中度适宜区分布在中北部和南部,较高适宜区位于中部以西太湖沿岸,高度适宜区位于紧临太湖的西南地区,极高适宜区位于西南角局部地区。(3)引入湖陆风指数后,评价结果能更好地反映临湖平原的湖陆风环流对局地气候所起的关键作用。(4)建立缓冲区后的水文指数分布能够更客观地反映吴江区不同尺度水体分布对人居环境自然选择的影响。 相似文献
826.
宋正海 《广东海洋大学学报》2006,26(5):14-19
对地理环境决定论是“资产阶级地理思想”提出质疑。并对人与自然关系进行系统梳理和反思:(1)地理环境决定论产生并发展于东西方两个伟大时代;(2)地理环境决定论在近代受到的批判是误解所致;(3)地理环境决定论大大丰富了历史唯物主义。提出地理环境决定论是人类优秀文化遗产。 相似文献
827.
C. S. COCKELL 《Earth, Moon, and Planets》2004,94(3-4):233-243
Regardless of the discovery of life on Mars, or of “no apparent life” on Mars, the questions that follow will provide a rich future for biological exploration. Extraordinary pattern recognition skills, decadal assimilation of data and experience, and rapid sample acquisition are just three of the characteristics that make humans the best means we have to explore the biological potential of Mars and other planetary surfaces. I make the case that instead of seeing robots as in conflict, or even in support, of human exploration activity, from the point of view of scientific data gathering and analysis, we should view humans as the most powerful robots we have, thus removing the separation that dogs discussions on the exploration of space. The narrow environmental requirements of humans, although imposing constraints on the life support systems required, is more than compensated for by their capabilities in biological exploration. I support this view with an example of the “Christmas present effect,” a simple demonstration of human data and pattern recognition capabilities. 相似文献
828.
C. S. M. Turney A. P. Kershaw P. Moss M. I. Bird L. K. Fifield R. G. Cresswell G. M. Santos M. L. Di Tada P. A. Hausladen Y. Zhou 《第四纪科学杂志》2001,16(8):767-771
Lynch's Crater preserves a continuous, high‐resolution record of environmental changes in north Queensland. This record suggests a marked increase in burning that appears to be independent of any known major climatic boundaries. This increase is accompanied, or closely followed, by the virtually complete replacement of rainforest by sclerophyll vegetation. The absence of any major climatic shift associated with this increase in fire frequency therefore has been interpreted as a result of early human impact in the area. The age for this increase in burning, on the basis of conventional radiocarbon dating, was previously thought to be approximately 38 000 14C yr BP, supporting the traditional model for human arrival in Australia at 40 000 14C yr BP Here we have applied a more rigorous pre‐treatment and graphitisation procedure for radiocarbon dating samples from the Lynch's Crater sequence. These new dates suggest that the increase in fire frequency occurred at 45 000 14C yr BP, supporting the alternative view that human occupation of Australia occurred by at least 45 000–55 000 cal. yr BP. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
829.
Ecological and social constraints are key for voluntary investments into renewable natural resources
Encouraging pro-environmental behavior is an urgent global challenge. An interdisciplinary framework covering governance, economic, social, ecological, and psychological dimensions is required to understand the salient features that encourage pro-environmental outcomes within and across contexts. We apply the Ostrom social-ecological systems framework to model voluntary investments by members of civil society into the aquatic environment. Using a data set of 1,809 angling clubs managing water bodies for fish stocking and habitat management in Germany and France, we show that a small set of factors, most crucially social-ecological and governance context as well as social norms and other bottom-up social pressures, drive environmental investments. These factors appear to override behavioral influences from psychological variables of the decision-maker. By contrast, the contextual setting related to property rights, size of the resource system, and social expectations were found to be strongly related to behavioral decisions, highlighting that the social-ecological context as well as incentives may be more important than knowledge and cognitions in driving certain pro-environmental actions. 相似文献
830.