全文获取类型
收费全文 | 754篇 |
免费 | 72篇 |
国内免费 | 96篇 |
专业分类
测绘学 | 20篇 |
大气科学 | 93篇 |
地球物理 | 50篇 |
地质学 | 180篇 |
海洋学 | 192篇 |
综合类 | 73篇 |
自然地理 | 314篇 |
出版年
2024年 | 2篇 |
2023年 | 11篇 |
2022年 | 25篇 |
2021年 | 37篇 |
2020年 | 28篇 |
2019年 | 34篇 |
2018年 | 30篇 |
2017年 | 39篇 |
2016年 | 44篇 |
2015年 | 36篇 |
2014年 | 46篇 |
2013年 | 66篇 |
2012年 | 46篇 |
2011年 | 64篇 |
2010年 | 38篇 |
2009年 | 45篇 |
2008年 | 45篇 |
2007年 | 33篇 |
2006年 | 34篇 |
2005年 | 36篇 |
2004年 | 22篇 |
2003年 | 15篇 |
2002年 | 24篇 |
2001年 | 12篇 |
2000年 | 16篇 |
1999年 | 14篇 |
1998年 | 18篇 |
1997年 | 20篇 |
1996年 | 9篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 5篇 |
1981年 | 2篇 |
排序方式: 共有922条查询结果,搜索用时 15 毫秒
211.
能源产业作为丝绸之路经济带建设的首推工程,影响丝绸之路经济带建设的整体进程。文章以能源消费结构为切入点,构建能源供应安全和使用安全的指标体系,运用回归方法对比分析了1992年~2013年中哈两国能源消费结构与能源安全的关联性。研究结果表明:两国传统的能源消费结构对能源安全的贡献呈现逐渐下降的趋势;两国能源安全均呈现"波动上升-波动下降"演进特征;两国能源安全形势都较为严峻,能源使用安全产生的环境负面效应凸显并逐渐放大。鉴于此,文章以两国能源合作为基础,从区域一体化层面审视并探究两国能源安全合作的深化路径。 相似文献
212.
The Urban Heat Island (UHI) is a well-documented phenomenon occurring in cities across the world resulting in city centres often being several degrees warmer than their surroundings. This local elevation in temperatures could potentially impact upon local energy consumption, with residents in the warmer central section of the city using more energy to cool their homes in summer and less energy to warm them in winter. This study uses a combination of Geographical Information System techniques and Remote Sensing data (MODIS LST and NDVI), as a preliminary investigation, to assess the spatial relationship between UHI, urban greenspace, household income and electricity consumption in Birmingham, UK. It provides simple and repeatable steps, based on freely available datasets, for urban planners, industry, human and physical geographers, and non-specialists to reproduce the analyses. The results show that, the present impact of the UHI is limited and instead highlights the dominance of household income over local climate in explaining consumption patterns across Birmingham. 相似文献
213.
随着社会研究的"空间转向"以及地理研究的"文化转向",城市消费空间成为城市社会研究与文化地理学研究的热点;然而在全球化推进过程中,地方化也在悄然兴起,玛吉阿米餐厅正是地方化催生的产物,并且自其开业以来就受到中外游客的青睐。基于这种背景,本文从经营者的空间建构和游客的感知两个角度,运用质性的研究方法对玛吉阿米进行研究,发现:经营者运用各种景观符号及名人轶事对空间进行建构与重构,使其成为一个极具民族风情与有故事的空间;而作为消费的游客,通过对实体空间、名人轶事的感知获得一种深刻的消费体验,而对餐厅的功能价值的感知程度较差,这也说明旅游消费也具有符号消费的倾向。 相似文献
214.
Many Mediterranean areas have recently witnessed a proliferation of new urban and tourist-related features following low-density residential patterns that contrast with the traditional high-density urban typologies of Mediterranean cities. The aim of this research is to investigate the links between residential tourism and water consumption through swimming pools, which constitute one key element of the new urban landscapes in the coast of Alicante (southeastern Spain). We have digitized pools in nine municipalities of coastal Alicante and calculated the average depth and estimated water losses due to evaporation. Results show that swimming pools are widely available in tourist residential enclaves but that they tend to display different characteristics according to factors such as the history of the urbanization process and relative wealth of the different areas. We have detected a clear contrast between the large individual pools of the richer northern municipalities and the smaller individual pools and community pools in the newly developed but less well-off urban enclaves of the southern coast. 相似文献
215.
216.
Isao Kudo Takeshi Yoshimura Choon-Weng Lee Mitsuru Yanada Yoshiaki Maita 《Journal of Oceanography》2007,63(5):791-801
Nutrient regeneration and oxygen consumption after a spring bloom in Funka Bay were studied on monthly survey cruises from
February to November 1998 and from March to December 1999. A high concentration of ammonium (more than 4 μmol l−1) was observed near the bottom (80–90 m) after April. Phosphate and silicate gradually accumulated and dissolved oxygen decreased
in the same layer. Salinity near the bottom did not change until summer, leading to the presumption that the system in this
layer is semi-closed, so regenerated nutrients were preserved until September. Nitrification due to the oxidation of ammonium
to nitrate was observed after June. Nitrite, an intermediate product, was detected at 4–7 μmol L−1 in June and July 1999. Assuming that decomposition is a first order reaction, the rate constant for decomposition of organic
nitrogen was determined to be 0.014 and 0.008 d−1 in 1998 and 1999, respectively. The ammonium oxidation rate increased rapidly when the ambient ammonium concentration exceeded
5 μmol L−1. We also performed a budget calculation for the regeneration process. The total amount of N regenerated in the whole water
column was 287.4 mmol N m−2 in 4 months, which is equal to 22.8 gC m−2, assuming the Redfield C to N ratio. This is 34% of the primary production during the spring bloom and is comparable to the
export production of 25 gC m−2 measured by a sediment trap at 60 m (Miyake et al., 1998). 相似文献
217.
盐度和pH值对鮸鱼幼鱼耗氧率和氨氮排泄率的影响 总被引:14,自引:0,他引:14
利用实验生态学的方法研究了不同盐度及pH值对鮸鱼幼鱼的呼吸、排泄的影响.结果表明,不同盐度对鮸鱼幼鱼耗氧率、氨氮排泄率有显著影响(P〈0.05),盐度11~26,鮸鱼幼鱼耗氧率逐步上升,26时达到峰值后呈下降趋势;pH值对耗氧率无显著影响(P〉0.05),pH6.5~9.0鮸鱼幼鱼耗氧率变化幅度很小,在此范围内pH值的变化对鮸鱼幼鱼氨氮排泄率有显著影响(P〈0.05).O:N比值也随着盐度升高而升高,26时达到峰值,随后下降;pH8.0时,O:N比值最低;不同盐度和pH下鮸鱼幼鱼平均O:N分别为24.258,22.378.鮸鱼幼鱼主要以蛋白质为能源,脂肪和碳水化合物其次. 相似文献
218.
219.
220.