全文获取类型
收费全文 | 119篇 |
免费 | 4篇 |
国内免费 | 12篇 |
专业分类
测绘学 | 3篇 |
地球物理 | 40篇 |
地质学 | 19篇 |
海洋学 | 69篇 |
自然地理 | 4篇 |
出版年
2023年 | 1篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 5篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 5篇 |
2012年 | 5篇 |
2011年 | 7篇 |
2010年 | 6篇 |
2009年 | 8篇 |
2008年 | 9篇 |
2007年 | 8篇 |
2006年 | 5篇 |
2005年 | 5篇 |
2004年 | 8篇 |
2003年 | 7篇 |
2002年 | 1篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
排序方式: 共有135条查询结果,搜索用时 15 毫秒
1.
2.
3.
Using benthic macrofauna to assess environmental quality of four intertidal mudflats in Hong Kong and Shenzhen Coast 总被引:4,自引:0,他引:4
Cai Lizhe Nora F. Y. Tam Teresa W. Y. Wong Ma Li Gao Yang Yuk-Shan Wong 《海洋学报(英文版)》2003,22(2):309-319
Abstract-Intertidal zone is a significant wetland between land and ocean. It plays an important rolein maintaining local ecological balance. Both Mai Po and Futian intertidal mudflats are located in Shen-zhen Bay and are important "refueling" point along the East Asian/Australian flyway of migratory birds.The environmental quality of Mai Po and Futian mudflats have aroused great concern due to rapid eco-nomic developments in Hong Kong and Shenzhen in recent decades. Microinfauna of Mai Po and Futianmudflats was investigated in December 2000 and the faunal data were used to assess their environmentalquality. Two other mudflats, namely Ma Wan Typhoon Shelter (a more disturbed area) and Luk Kengintertidal mudflat (a place with relatively less human disturbance), were also sampled for macroinfaunaand used as reference mudflats. Shannon-Weaver species diversity index (I_(sd)), biotic coefficient (C_b)and macrofaunal pollution index (I_(mp)) of the macrofauna community on four intertidal mudflats wereused to 相似文献
4.
厦门潮间带表层沉积物天然放射系不平衡研究 总被引:5,自引:0,他引:5
用HPGeγ谱仪测定了厦门潮间带表层沉积物中的放射性核素,得到11种核素238U2、34Th2、26Ra2、22Rn2、10Pb2、28Ra2、28Ac2、28Th2、24Ra2、12Pb、40K的平均比活度分别为:40.2、82.7、32.4、28.9、94.2、69.3、57.1、71.6、64.0、71.4、692Bq/kg.结果表明潮间带沉积物中天然放射系不平衡,其中234Th相对于238U2、10Pb相对于226Ra过剩,222Rn相对于226Ra2、28Ac相对于228Ra2、24Ra相对于228Th亏损. 相似文献
5.
L.J. Hou M. Liu J.J. Lu S.Y. Xu D.N. Ou Y. Yang D.G. Zheng 《Environmental Geology》2006,49(7):937-945
The influences of exposure to the atmosphere on ammonium cycle in the intertidal surface sediments were in situ studied with
a geochemical approach at a typical station in the Yangtze Estuary during three tidal cycles in September 2003. During an
about 8-h emersion period of each diurnal tide, six high-resolution vertical profiles of adsorbed and dissolved ammonium were
measured. It was observed that both adsorbed and dissolved ammonium generally had an increasing trend in sediment cores during
the exposure. The rate of ammonium regeneration in sediments was estimated using the accumulation amount of ammonium including
adsorbed and soluble fractions during the daytime emersion. The calculation result showed that there was relatively high ammonification
rate (˜500 nmol N cm−3 day−1), which reflected that organic nitrogen in sediments was quickly decomposed with a residence time of ˜52.7 days. Due to the
dramatic temperature difference observed in sediment profiles, free convection was considered an important mechanism of regulating
the efflux of produced ammonium into overlying waters. The total estimated amount of regenerated ammonium was ˜1.35×105 t N year−1 in the intertidal flat of the Yangtze Estuary, which occupied 7.6% of the total inorganic nitrogen annually transported to
the estuarine ecosystem. 相似文献
6.
The stability of cohesive and non-cohesive sediments in a mixed intertidal habitat within the Ria Formosa tidal lagoon, Portugal, was examined during two field campaigns as part of the EU F-ECTS project. The cohesive strength meter Mk III was used to determine critical erosion shear stress (τc) within a variety of different intertidal habitats and substrata, including Spartina maritima fields and Zostera noltii beds. The best predictor(s) for τc were derived from a range of properties measured for the surface sediments (chlorophyll a, colloidal carbohydrate, water, organic content, % fraction <63 μm, and seabed elevation). Pigment biomarkers were used to identify the dominant algal groups within the surface phytobenthic assemblage.Strong, seasonally dependent relationships were found between τc and habitat type, chl a, colloidal carbohydrate and bed elevation. Typically, critical erosion thresholds decreased seawards, reflecting a change from biostabilisation by cyanobacteria in the upper intertidal areas, to biostabilisation by diatoms on the bare substrata of the channel edges. In the late summer/early autumn, cyanobacteria were the main sediment stabilisers, and colloidal carbohydrate was the best bio-dependent predictor of τc across the entire field area. In the late winter/early spring, cyanobacterial activity was lower, and sediment stabilisation by Enteromorpha clathrata was important; the best predictor of τc was bed elevation. The implications and use of proxies for sediment stability are discussed in terms of feedback and sedimentation processes operating across the intertidal area. 相似文献
7.
In order to determine time-dependent changes in estuarine pore-water chemistry and flux variations across the sediment-water interface, sediment cores of an intertidal mud flat in the Weser Estuary were taken monthly over a one-year period. Sediment temperature, pH, Eh, Cl–, O2, NO
3
–
, and SO
4
2–
pore-water concentrations were measured and showed variations that relate to the changes of surface temperature and estuarine water composition. Fick's first law was applied to quantify diffusive fluxes from concentration gradients in the diffusive boundary layer and in the pore water. Total nitrate fluxes were calculated from flux chamber experiments. Diffusive oxygen fluxes increased from 5 mmol m–2 d–1 in winter to 18 mmol m–2 d–1 in early summer, while nitrate fluxes into the sediment increased from 3 mmol m–2 d–1 in winter to 60 mmol m–2 d–1 in early summer. Oxygen and nitrate fluxes into the sediment correlated linearly to sediment temperature. Sulfate fluxes increased from 0.5 mmol m–2 d–1 in winter to 10 mmol m–2 d–1 in August and September. Converted into carbon fluxes, the sum of these oxidants ranged from 10 mmol m–2 d–1 in winter to 80 mmol m–2 d–1 in summer. An estimation of the upper limit of the annual nitrate flux into the sediment showed that about 10% of the 250,000 t of nitrate discharged annually by the river may be decomposed within the inner Weser Estuary. 相似文献
8.
Transformation of arsenic compounds in modern intertidal sediments of Iriomote Island, Japan 总被引:1,自引:0,他引:1
The arsenic accumulation process in intertidal sediments of Iriomote Island, Japan, is analyzed as a naturally balanced arsenic-fixation system. Major and minor element chemistry is analyzed by X-ray fluorescence photometry, mineralogy is investigated by X-ray diffractometry, and four arsenic compounds are characterized by hydrogen-generated atomic absorption photometry. It is found that arsenic is accumulated by iron hydroxides/oxides precipitated following the decomposition of humic acids in the shallower sediment, and is subsequently incorporated into iron sulfide minerals at depth. The arsenic is immobile during incorporation into arsenic-bearing phases, suggesting that arsenic is unlikely to be released into the porewater under natural conditions in early diagenesis. The formation and decomposition of arsenic-bearing organic compounds appear to be associated with the formation and decomposition of arsenic in oxyhydroxides/oxides, suggesting that microbial activity may play an important role in controlling the behavior of arsenic and arsenic-bearing phases in the sediment column. 相似文献
9.
荣成月湖是一个典型天然潟湖,潮间带沉积物中存在多种形态趋磁细菌。通过Roche454高通量测序平台,对沉积物样品(B_S)和磁收样品(B_M)进行16SrRNA基因高通量测序,认识荣成潮间带沉积物的细菌群落结构,并了解趋磁细菌多样性及系统进化地位。研究结果表明沉积物样品中主要的细菌类群为δ-变形菌纲,占总细菌数的26.4%,其次是γ-变形菌纲和α-变形菌纲;而磁收样品中细菌多样性和种类明显降低,以α-变形菌纲占绝对优势,相对比例达72.6%。在磁收样品和沉积物样品分别发现了1 612条和186条reads与趋磁细菌相关,分别占细菌总数的5.76%和0.85%,磁收样品中趋磁细菌数是沉积物样品的6.8倍。对两个样品中获得的趋磁细菌序列进行系统进化分析,发现这些序列多数属于变形菌门的α-变形菌纲,以趋磁球菌占绝对优势,少数属于δ-变形菌纲,与多细胞趋磁原核生物亲缘关系最近。海洋趋磁螺菌属仅在B_M样品中检出,趋磁弧菌属在B_M样品优势度高于B_S样品,而多细胞趋磁原核生物和趋磁螺菌属在B_S样品中优势度更高。通过分析样品间的差异OTUs,认为荣成潮间带沉积物中可能存在大量未知的趋磁细菌新类群。研究结果为下一步培养和开发趋磁细菌这一功能菌群,发现趋磁细菌新类群及趋磁细菌生态功能提供了基础资料。 相似文献
10.
为了验证设计的简易厌氧培养方法,作者以青岛潮间带沉积物为研究对象,采用5种培养基,从青岛潮间带沉积物共分离获得138株厌氧细菌。16S r DNA序列分析表明,这些细菌分属3个门15个属32个种,其中γ-变形菌纲64株18个种,在种类上处于优势地位;此外还包括δ-变形菌纲(δ-Proteobacteria)16株2个种,ε-变形菌纲4株1个种,拟杆菌门(Bacteroidetes)29株8个种,梭杆菌门(Fusobacteria)25株3个种。在属水平上,弧菌属(Vibrio)、Marinifilum属、泥杆菌属(Ilyobacter)、脱硫弧菌属(Desulfovibrio)、希瓦氏菌属(Shewanella)在数量上占优势。此外,有26株8种细菌(占总菌株数的18.84%)与已知菌的同源性介于89.38%~94.22%,为潜在的海洋细菌新科或新属,表明此简易厌氧菌培养方法在获得新菌方面具有较大优势。另外,研究结果还表明,不同培养基对特定的类群具有选择性:2216E培养基对γ-变形菌纲分离培养效率较高;SPG培养基在获得新菌方面具有优势(占新菌数62.5%),且这些新菌大多属于拟杆菌门和梭杆菌门,其中SPG-1培养基对于分离硫酸盐还原菌和难培养的ε-变形菌纲细菌具有优势,SPG-4培养基对分离硝酸盐还原菌具有优势。 相似文献