全文获取类型
收费全文 | 4437篇 |
免费 | 880篇 |
国内免费 | 713篇 |
专业分类
测绘学 | 85篇 |
大气科学 | 86篇 |
地球物理 | 1336篇 |
地质学 | 3517篇 |
海洋学 | 151篇 |
天文学 | 6篇 |
综合类 | 230篇 |
自然地理 | 619篇 |
出版年
2024年 | 22篇 |
2023年 | 29篇 |
2022年 | 127篇 |
2021年 | 199篇 |
2020年 | 183篇 |
2019年 | 186篇 |
2018年 | 198篇 |
2017年 | 174篇 |
2016年 | 203篇 |
2015年 | 209篇 |
2014年 | 284篇 |
2013年 | 402篇 |
2012年 | 264篇 |
2011年 | 258篇 |
2010年 | 268篇 |
2009年 | 272篇 |
2008年 | 304篇 |
2007年 | 328篇 |
2006年 | 348篇 |
2005年 | 290篇 |
2004年 | 215篇 |
2003年 | 204篇 |
2002年 | 148篇 |
2001年 | 144篇 |
2000年 | 123篇 |
1999年 | 151篇 |
1998年 | 114篇 |
1997年 | 74篇 |
1996年 | 72篇 |
1995年 | 65篇 |
1994年 | 27篇 |
1993年 | 37篇 |
1992年 | 25篇 |
1991年 | 16篇 |
1990年 | 13篇 |
1989年 | 8篇 |
1988年 | 16篇 |
1987年 | 8篇 |
1986年 | 4篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1976年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有6030条查询结果,搜索用时 15 毫秒
111.
Linda J. Anderson-Berry 《Natural Hazards》2003,30(2):209-232
This paper is a partial discussion of a four-year study that investigated the vulnerability of the people living in the Cairns region to the tropical cyclone hazard. The longitudinal case study, focussing on the Cairns Northern Beaches area, was unique in that it included a social and societal `pre-cyclone impact' evaluation of various resident communities within the region, and then two consecutive `post-cyclone impact' studies. The primary research method supported an inductive qualitative approach to the collection and analysis of survey data. Some quantitative methods were invoked to support qualitative research findings. Survey data was collected in five separate questionnaire-based social surveys that were administered between 1996 and 2000. During the study, residents experiencedthe direct impact of two land-falling tropical cyclones. In addition to this, targeted andfocussed tropical cyclone awareness education was made increasingly available withinthe community. The social and demographic attributes that influence the individual'sperception of risk and contribute to our understanding of community vulnerability were examined and evaluated. Changes in the residents' attitudes, cyclone preparednessbehaviours and willingness to respond to cyclone warnings were monitored and measured. Analysis of early survey data indicated that community residents generally had some knowledge of cyclones but a limited understanding of cyclone processes and very little direct personal experience of the cyclone hazard. Individually and collectively, residents frequently demonstrated a biased perception of the risks associated with cyclones. The resident community was shown to be fragmented, with limited support being available to individual households. Initially, residents were found to be poorly prepared for cyclones and unlikely to respond to warnings appropriately. It appeared that, in the event of a land-falling tropical cyclone impacting the area, the community was highly vulnerable to unnecessary loss of property, livelihood and – in extreme circumstances – life. By 2000, Cairns community residents were somewhat better informed about cyclones and certainly more experienced. This paper provides some insight into how cyclone experience and education may synergisticly have contributed to a change in risk perceptions and a reduction in the vulnerability of Cairns residents to the tropical cyclone and storm surge hazards. 相似文献
112.
随着郑州市城市化进程的飞速发展和规模的不断扩大,尤其是郑东新区的建设,需水量急剧增加。为缓解郑州市供水紧张状况,调整引黄水量与地下水开采量的比例,确保郑州供水安全,需在黄河岸边开采地下水,水源地开采后,地下水流场范围内水位将下降,地下水流场的改变对黄河堤防稳定性是否产生影响,对此进行了初步研究和探讨。研究结果表明,开采浅层地下水,不会对黄河大堤造成危害。 相似文献
113.
114.
目的 医学核磁共振与地面核磁共振找水是核磁共振技术应用的不同领域。本文通过对二者在方法原理、技术、应用等方面的对比研究,提出了地面核磁共振找水工作建议。 相似文献
115.
通过对昆明经济技术开发区的地质构造,场地工程地质环境,砂土液化判别以震害预测的综合研究,进行了区内的场地地震易损性分析。根据计算出的地震易损性指数,结果表明,可将研究区划分为两个震害程度不同的区域。 相似文献
116.
阐述了如何利用地下水宏观异常作强烈地震的临震预报,详细叙述了利用地下水宏观异常预报地震三要素的方法。 相似文献
117.
氮同位素比(^15N/^14N)在地下水氮污染研究中的应用基础 总被引:25,自引:1,他引:25
华北地下水中硝态氮浓度和δ^15N值如下:在自然状态下为4.4≤+5,来自下水道粪便污染者为20-70和+10-+20,受化肥污染者为30-60和-2-+5。因此,氮同位素可用来识别氮污染来源和氮的迁移。 相似文献
118.
L.L. Chyi 《International Journal of Coal Geology》1997,33(4):317-331
The Harlem coal is postulated to have been deposited in raised-bog settings. It was initially deposited as low-sulfur peat, but groundwater of a later origin altered portions of it to high-sulfur coal. The total sulfur content of 172 samples from 31 locations on a moisture- and ash-free basis have a quadrimodal distribution with two major modes at 0.75% S and 2.0%S. Multiple sampling and analyses at specific mine sites indicate that the addition of sulfur of a later origin occurred either laterally adjacent to sandstone channels or vertically adjacent to faults. Significant sulfur addition also occurred above clay partings at these sites. The original low-sulfur nature is preserved where the coal bed is isolated from descending groundwater by a thick impervious layer. Trace-element analyses show high concentrations of mobile elements such as Na and Mn in the high-sulfur coals. 相似文献
119.
地理信息系统(GIS)在地下水领域中的应用及最新进展 总被引:6,自引:0,他引:6
GIS是信息时代的产物,在地下水资源领域的研究日益广泛和深入。笔者着重阐述了GIS在地下水领域的应用及最新发展,同时对GIS在地下水应用中的优点和局限性提出了自己的观点。 相似文献
120.
浅层地下水氟的溶解/沉淀作用的定量研究 总被引:12,自引:0,他引:12
以河北邢台山前平原浅层高氟地下水为例,根据氟的化学热力学分析,确定了控制浅层地下水中氟迁移和富集的固相沉淀物,以及不同化学类型的浅层地下水中含氟固相沉淀物的溶解/沉淀条件;利用浅层地下水化学平衡反应模型和PHREEQE软件,确定了氟化的稳定区域,计算了氟化钙的饱和指数.研究结果表明,在浅层高氟地下水的整个形成过程中,都表现为氟由固相转入水相的趋势,有利于氟的迁移和富集 相似文献