全文获取类型
收费全文 | 868篇 |
免费 | 105篇 |
国内免费 | 91篇 |
专业分类
测绘学 | 18篇 |
大气科学 | 70篇 |
地球物理 | 248篇 |
地质学 | 409篇 |
海洋学 | 103篇 |
天文学 | 16篇 |
综合类 | 37篇 |
自然地理 | 163篇 |
出版年
2024年 | 3篇 |
2023年 | 8篇 |
2022年 | 27篇 |
2021年 | 25篇 |
2020年 | 32篇 |
2019年 | 24篇 |
2018年 | 19篇 |
2017年 | 47篇 |
2016年 | 41篇 |
2015年 | 35篇 |
2014年 | 35篇 |
2013年 | 46篇 |
2012年 | 27篇 |
2011年 | 51篇 |
2010年 | 40篇 |
2009年 | 42篇 |
2008年 | 74篇 |
2007年 | 59篇 |
2006年 | 48篇 |
2005年 | 35篇 |
2004年 | 34篇 |
2003年 | 30篇 |
2002年 | 36篇 |
2001年 | 28篇 |
2000年 | 20篇 |
1999年 | 21篇 |
1998年 | 46篇 |
1997年 | 23篇 |
1996年 | 25篇 |
1995年 | 19篇 |
1994年 | 12篇 |
1993年 | 11篇 |
1992年 | 13篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 6篇 |
1987年 | 1篇 |
1984年 | 2篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有1064条查询结果,搜索用时 0 毫秒
111.
112.
《China Geology》2020,3(1):124-136
Utilization of urban underground space has become a vital approach to alleviate the strain on urban land resources, and to optimize the structure and pattem of the city. It is also very important to improve the city environment, build livable city and increase the capacity of the city. Based on the analysis of existing evaluation methods and their problems, a method for evaluating underground space resources based on a negative list of adverse factors affecting underground space development is proposed, to be primarily used in urban planning stages. A list of the adverse factors is established, including limiting factors, constraining factors and influencing factors. Taking Xi’an as an example, using a geographical information system platform, a negative list of adverse factors for the underground space resources in Xi’ an City are evaluated, and preventive measures are proposed. Natural resources, exploitable resources, and the potential growth of exploitable underground space resources are evaluated. Underground space assessment in the different development stages of the city, collaborative utilization and safety evaluation for multiple subsurface resources, environmental impact and assessment, as well as evaluation methods based on big data and intelligent optimization algorithms are all discussed with the aim of serving city planning and construction. 相似文献
113.
石门台自然保护区水资源及其利用保护 总被引:2,自引:0,他引:2
介绍了广东英德市北部山区石门台自然保护区的自然地理条件、水文效应、水资源特点及其开发利用现状 ,提出对水资源的保护管理措施 ,促进自然环境良性循环 ,促进水资源可持续利用和社会经济发展。 相似文献
114.
115.
Jing Li Chang-ling Liu Neng-you Wu Xiao-qing Xu Gao-wei Hu Yan-long Li Qing-guo Meng 《China Geology》2022,5(2):285-292
Large amounts of gas hydrate are distributed in the northern slope of the South China Sea, which is a potential threat of methane leakage. Aerobic methane oxidation by methanotrophs, significant methane biotransformation that occurs in sediment surface and water column, can effectively reduce atmospheric emission of hydrate-decomposed methane. To identify active aerobic methanotrophs and their methane oxidation potential in sediments from the Shenhu Area in the South China Sea, multi-day enrichm... 相似文献
116.
117.
This study developed a finite element method with the effect of soil–fluid–structure interaction to calculate bridge natural frequencies. The finite element model includes bridge girders, piers, foundations, soil, and water. The effective mass above the soil surface was then used to find the first natural frequency in each direction. A field experiment was performed to validate that the natural frequencies calculated using the proposed finite element method had acceptable accuracy. The calculated natural frequencies with the fluid–structure interaction effect are always smaller than those without this effect. However, the frequency change due to the fluid effect is not obvious, so using the soil–structure interaction model is accurate enough in the bridge natural frequency analysis. The trend of the frequency decreases with the increase of the scour depth, but the curve is not smooth because of non-uniform foundation sections and layered soils. However, when the scour depth is such that pile cap is exposed, the changes in natural frequency with the scour depth are more obvious, and this is useful for measurement of the depth using bridge natural frequencies. 相似文献
118.
119.
Anke Fischer Vera PetersJan Vávra Mirjam NeebeBoldizsár Megyesi 《Global Environmental Change》2011,21(3):1025-1034
Citizens’ support for policies that aim to curb carbon emissions and energy use is often seen as informed by their values, attitudes and perceptions of the environmental problem in question. We argue that we also need to understand how people conceptualise policies and the governance approaches underpinning them to be able to judge the likely acceptance of policy change.In this study, we draw on qualitative interviews (n = 202) from five European countries to explore citizens’ views on governance approaches to stimulate behavioural change in the field of resource use, including regulations, price changes, collective action, technological change and education.We found that many of our interviewees referred to generalised characteristics of humankind and contemporary society to back up their arguments for or against specific governance approaches. In particular, many interviewees concurred that people in general were so self-centred, driven by habit and money- and consumption-oriented that only strict regulations, drastic price changes and technological innovation could possibly achieve widespread behavioural change. As a consequence, such ‘folk psychologies’ can have substantial impact not only on public acceptance, but also on the success of policy measures that aim to reduce citizens’ resource use. 相似文献
120.
Marleen Coetsiers Petra Blaser Kristine Martens Kristine Walraevens 《Environmental Geology》2009,57(5):1155-1168
Aquifers from the same typology can have strongly different groundwater chemistry. Deducing the groundwater quality of less
well-characterized aquifers from well-documented aquifers belonging to the same typology should be done with great reserve,
and can only be considered as a preliminary approach. In the EU’s 6th FP BRIDGE project “Background cRiteria for the IDentification
of Groundwater thrEsholds”, a methodology for the derivation of threshold values (TV) for groundwater bodies is proposed.
This methodology is tested on four aquifers in Flanders of the sand and gravel typology. The methodology works well for all
but the Ledo-Paniselian aquifer, where the subdivision into a fresh and saline part is disproved, as a gradual natural transition
from fresh to saline conditions in the aquifer is observed. The 90 percentile is proposed as natural background level (NBL)
for the unconfined Pleistocene deposits, ascribing the outliers to possible influence of pollution. For the Tertiary aquifers,
high values for different parameters have a natural origin and the 97.7 percentile is preferred as NBL. The methodology leads
to high TVs for parameters presenting low NBL, when compared to the standard used as a reference. This would allow for substantial
anthropogenic inputs of these parameters. 相似文献