全文获取类型
| 收费全文 | 75篇 |
| 免费 | 10篇 |
| 国内免费 | 22篇 |
专业分类
| 测绘学 | 8篇 |
| 大气科学 | 18篇 |
| 地球物理 | 26篇 |
| 地质学 | 21篇 |
| 海洋学 | 15篇 |
| 天文学 | 1篇 |
| 综合类 | 3篇 |
| 自然地理 | 15篇 |
出版年
| 2024年 | 1篇 |
| 2023年 | 1篇 |
| 2022年 | 6篇 |
| 2021年 | 5篇 |
| 2019年 | 5篇 |
| 2018年 | 6篇 |
| 2017年 | 5篇 |
| 2016年 | 4篇 |
| 2015年 | 4篇 |
| 2014年 | 4篇 |
| 2013年 | 5篇 |
| 2012年 | 4篇 |
| 2011年 | 5篇 |
| 2010年 | 3篇 |
| 2009年 | 9篇 |
| 2008年 | 6篇 |
| 2007年 | 6篇 |
| 2006年 | 5篇 |
| 2005年 | 4篇 |
| 2004年 | 4篇 |
| 2003年 | 3篇 |
| 2002年 | 4篇 |
| 2001年 | 3篇 |
| 2000年 | 1篇 |
| 1999年 | 2篇 |
| 1997年 | 1篇 |
| 1979年 | 1篇 |
排序方式： 共有107条查询结果，搜索用时 15 毫秒
81.
Methylmercury (MeHg) and inorganic mercury (Hginorg) were evaluated in the water of a Brazilian estuary, with two size classes of plankton and seven fish species of different feeding habits. Water partition coefficients (PCs) in microplankton were fourfold higher for MeHg than for Hginorg; and water PCs in mesoplankton were 26 times higher for MeHg than Hginorg. Difference between microplankton and mesoplankton MeHg bioaccumulation factor (BAF) was higher (0.60 log units) than Hginorg BAF (0.24 log units), indicating that trophic transfer of MeHg between planktonic organisms is more efficient than Hginorg transference. MeHg concentrations, proportion of mercury as MeHg and its biotransference factors (BTFs) in the microplankton, mesoplankton and fish increased with increasing trophic level while biotic concentrations of Hginorg and proportion of mercury as Hginorg decreased thus indicating that MeHg was indeed the biomagnified species of mercury. MeHg reflected the vertical trophic guilds distribution, due to the fact that the top predator fish presented the highest concentration (0.77 μg g−1 d.w.), followed by the less voracious species (0.43 μg g−1 d.w.); while planktivorous fish presented the lowest concentrations (0.044 μg g−1 d.w.). Hginorg did not present the same behavior. Results suggest that feeding habits and trophic guild are important parameters, influencing biotransference and biomagnification processes. 相似文献
82.
83.
84.
85.
86.
87.
88.
英国海上风电产业起步较晚,但发展迅猛,成为全球海上风电产业的领头羊。英国海上风电产业扶持政策依次经历过非化石燃料义务制度、可再生能源义务制度、差价合约制度等阶段。差价合约制度作为可再生能源义务制度的后继制度,在制度上有较多的创新之处,有效地推动了英国海上风电产业的发展。文章基于差价合约制度与可再生能源义务制度的分析和比较,结合英国海上风电2030年规划目标,深入分析发现差价合约制度对英国海上风电产业发展具有较大的推动力。研究表明,差价合约制度改进了可再生能源义务制度的不足之处,能够充分利用市场机制提高海上风电企业的投资热情,降低消费者的电力消费成本,并可减轻政府的财政压力,从而推动英国海上风电产业的快速发展,这对我国具有一定借鉴意义。 相似文献
89.
H.A. Kehrig E.F.A. Palermo T.G. Seixas C.W.C. Branco I. Moreira O. Malm 《Estuarine, Coastal and Shelf Science》2009
Methylmercury (MeHg) and trace elements (TE), mercury, selenium, cadmium, lead and copper, were determined in a microbial loop composed by three size classes of autotrophic and heterotrophic microorganism samples, 1.2–70 μm (seston, SPM), 70–290 μm (microplankton) and ≥290 μm (mesoplankton) from five sampling stations within a polluted eutrophic estuary in the Brazilian Southeast coast and one external point under the influence of the bay. TE concentrations were within the range reported for marine microorganisms from uncontaminated locations. Microplankton was primarily composed of proto-zooplankton and diatoms (>90%) while approximately 50% of mesoplankton was composed mainly of copepods. MeHg and TE in samples did not differ among the five sampling stations within the bay. Cd, Pb and Cu in seston were higher in the stations sampled inside Guanabara Bay (0.67 μg Cd g−1, 9.26 μg Pb g−1, 8.03 μg Cu g−1) than in the external one (0.17 μg Cd g−1, 3.98 μg Pb g−1 and 2.09 μg Cu g−1). Hg, MeHg and Se did not differ among the five points within the more eutrophic waters of the estuary and the external sampling station. The trophic transfer of MeHg and Se was observed between trophic levels from prey (seston and microplankton) to predator (mesoplankton). The successive amplification of the ratios of MeHg to Hg with increasing trophic levels from seston (43%), to microplankton (59%) and mesoplankton (77%) indicate that biomagnification may be occurring along the microbial food web. Selenium, that is efficiently accumulated by organisms through trophic transference, was biomagnified along the microbial food web, while Hg, Cd, Pb, Cu did not present the same behavior. Concentrations differed between the three size classes, indicating that MeHg and TE accumulation were size-dependent. MeHg and TE concentrations were not related to the taxonomic groups' composition of the planktonic microorganisms. Results suggest the importance of the role of the trophic level and microorganism size in regulating element transfers. Eutrophication dilution may provide a process-oriented explanation for lower MeHg and TE accumulation by the three size classes of microorganisms collected at the five sampling stations within the bay. 相似文献
90.