全文获取类型
收费全文 | 274篇 |
免费 | 10篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 19篇 |
地球物理 | 70篇 |
地质学 | 90篇 |
海洋学 | 32篇 |
天文学 | 38篇 |
自然地理 | 33篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2021年 | 7篇 |
2020年 | 13篇 |
2019年 | 11篇 |
2018年 | 12篇 |
2017年 | 20篇 |
2016年 | 15篇 |
2015年 | 5篇 |
2014年 | 14篇 |
2013年 | 16篇 |
2012年 | 8篇 |
2011年 | 18篇 |
2010年 | 19篇 |
2009年 | 17篇 |
2008年 | 18篇 |
2007年 | 11篇 |
2006年 | 14篇 |
2005年 | 14篇 |
2004年 | 9篇 |
2003年 | 8篇 |
2002年 | 10篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有284条查询结果,搜索用时 15 毫秒
71.
Ana Cecília Rizzatti de Albergaria-Barbosa Vinicius Faria Patire Satie Taniguchi Wellington Silva Fernandez June Ferraz Dias Márcia Caruso Bícego 《Marine pollution bulletin》2017,114(1):609-614
This work aimed to evaluate the use of Mugil curema as a biomonitor for polycyclic aromatic hydrocarbon (PAH) bioavailability. Fish biliary metabolites from low-contaminated (Cananéia) and contaminated (Santos) Brazilian estuaries were analysed using a high-performance liquid chromatography apparatus coupled to fluorescence detectors connected in a series. In the Cananéia and Santos estuaries, total metabolite levels ranged from 0.85 to 34.4 μg g? 1 of bile and from 4.06 to 528 μg g? 1 of bile, respectively. Metabolite levels were not influenced by feeding status or sexual hormones (p < 0.05), thus suggesting that M. curema is a good biomonitor for PAH bioavailability. In estuarine regions, it is possible to sample both the male and female genders of this species in any reproductive period. 相似文献
72.
Fires produce an aromatic particulate residue commonly referred to as pyrogenic carbon (PyC). Particulate PyC is low density, high porosity, and is predominantly deposited on the soil surface in post-fire landscapes. These characteristics create a material that is prone to mobility, both vertically down the soil profile and laterally across the landscape even in low-relief landforms. Because of its tendency for lateral mobilization, we argue here that PyC's first interaction with water determines its environmental fate and persistence, not its interactions with soil minerals or microbes. PyC's first interactions with water determine: the amount of PyC that will enter the soil profile and experience microbial and geochemical alterations, whether it will be buried in depositional environments and stored on the landscape, or if it will be transported to streams and eventually to the ocean. Here we posit that this crucial first interaction with the hydrologic cycle occurs on the timescale of days to weeks, and therefore supersedes microbial decomposition as the primary control on PyC's environmental persistence. © 2020 John Wiley & Sons, Ltd. 相似文献
73.
Laura Knoth Manfred Mittlbck Bernhard Vockner Michael Andorfer Caroline Atzl 《Transactions in GIS》2019,23(3):435-449
Digital building information is important during a building's lifecycle, it is needed from first design until demolition. The two domains that mainly contribute are AEC (architecture, engineering, and construction) during design, construction, and operation, and GIS as a supporting discipline for analysis and further integration of the building's environment. However, there is a challenge in information exchange between the two domains, resulting in the remodeling of digital building information in GIS. In this article, we identify three major data sources from the AEC domain and show transformation processes to enable the integration of such models into the geographical environment in the form of one transition model. Furthermore, we show that this model can either be used directly or exported in the form of de facto standards that allow for further analysis. 相似文献
74.
We review the current knowledge about Southeast Asian volcanoes and their eruption histories, and focus on identifying tephrochronologic markers representing major explosive eruptions in order to further future palaeoclimate and volcanological studies. Forty-one volcanic edifices in Southeast Asia have been classified as large calderas by Whelley et al. (2015) and thus have, or are likely to have, produced large explosive eruptions with a Volcanic Explosivity Index (VEI) of 6–8. Unfortunately, only 20 such eruptions have known ages, spanning from 1.2 Ma to 1991 ad , and fewer have geochemical data that can be used for tephrostratigraphic correlations. Volcanic products from different geodynamic regions and different sources can generally be distinguished on major element plots (e.g. K2O versus CaO) of matrix glass composition. However, the distinction of multiple eruptions from the same source often requires additional data such as trace element compositions of matrix glass and/or mineral compositions. Biotite, but also magnetite compositions (MgO and TiO2 content in particular) appear to be very discriminating. Up to nine tuffs in addition to the three to four Toba tuffs can be utilised as widespread tephrochronologic markers and span a range from 1.2 to 1.6 Ma to recent. As only a few Holocene major eruptions have been well characterised and dated, many large calderas are still unstudied, and many distal tephra layers are still lacking a source, more tephrochronologic markers can certainly be defined in the future. 相似文献
75.
Jérôme Harlay Caroline De Bodt Anja Engel Sandra Jansen Quentin d’Hoop Judith Piontek Nicolas Van Oostende Steve Groom Koen Sabbe Lei Chou 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(8):1251-1265
The distribution of transparent exopolymer particles (TEP) was investigated during a coccolithophorid bloom in the northern Bay of Biscay (North Atlantic Ocean) in early June 2006. MODIS chlorophyll-a (Chl-a) and reflectance images before and during the cruise were used to localize areas of important biological activity and high reflectance (HR). TEP profiles along the continental margin, determined using microscopic (TEPmicro) and colorimetric (TEPcolor) methods, showed abundant (6.1×106–4.4×107 L?1) and relatively small (0.5–20 μm) particles, leading to a low total volume fraction (0.05–2.2 ppm) of TEPmicro and similar vertical profiles of TEPcolor. Estimates of carbon content in TEP (TEP-C) derived from the microscopic approach yielded surface concentration of 1.50 μmol C L?1. The contribution of TEP-C to particulate organic carbon (POC) was estimated to be 12% (molar C ratio) during this survey. Our results suggest that TEP formation is a probable first step to rapid and efficient export of C during declining coccolithophorid blooms. 相似文献
76.
Harold C. Connolly Caroline Smith Gretchen Benedix Luigi Folco Kevin Righter Jutta Zipfel Akira Yamaguchi Hasnaa Chennaoui Aoudjehane 《Meteoritics & planetary science》2007,42(9):1647-1694
Abstract— In this edition of The Meteoritical Bulletin, 1394 recognized meteorites are reported, 27 from specific locations within Africa, 133 from Northwest Africa, 1227 from Antarctica (from ANSMET, PNRA, and PRIC expeditions), and 7 from Asia. The Meteoritical Bulletin announces the approval of four new names series by the Nomenclature Committee of the Meteoritical Society, two from Africa and one from Asia, including Al Haggounia, from Al Haggounia, Morocco, which is projected to be on the order of 3 metric tons of material related to enstatite chondrites and aubrites. Approved are two falls from Africa, Bassikounou (Mauritania) and Gashua (Nigeria). Approved from areas other than Antarctica are one lunar, two Martian, 32 other achondrites, three mesosiderites, two pallasites, one CM, two CK, one CR2, two CV3, one CR2, and four R chondrites. The Nomenclature Committee of the Meteoritical Society announces 48 newly approved relict meteorites from two new name series, Österplana and Gullhögen (both from Sweden). 相似文献
77.
Equilibration Scales in Silicic to Intermediate Magmas Implications for Experimental Studies 总被引:5,自引:0,他引:5
Pichavant Michel; Costa Fidel; Burgisser Alain; Scaillet Bruno; Martel Caroline; Poussineau Stephane 《Journal of Petrology》2007,48(10):1955-1972
Experimental phase equilibrium studies are increasingly beingused for the determination of intensive variables (P, T, fH2O,fO2 ) in silicic to intermediate magmas. In contrast, silicicigneous bodies are now perceived as open, periodically recharged,systems involving only limited chemical equilibration. Thus,the use of laboratory-determined crystal–liquid equilibriumdata needs clarification. Here we review the field, petrologicaland geochemical evidence concerning states and scales of chemicalequilibrium in silicic magma bodies. It is concluded that totalchemical equilibrium is generally not the rule. However, a subsystemin local equilibrium (the reactive magma) can be identified.Equilibration scales in silicic magmas are rate-limited eitherby diffusive flux in crystals (DICL regime) or by diffusiveflux in the melt (MD regime). The recognition that equilibriumin magmas is limited to a reactive subsystem requires phaseequilibrium studies to be chemically scaled. Experiments, eitherof total or partial equilibrium type, should aim at a closereproduction of equilibrium states specific to natural systems.The laboratory reconstruction of the natural equilibrium statesguarantees a precise determination of the pre-eruptive parametersand a reliable application of the experimental data to activevolcanic systems. KEY WORDS: silicic magmas; chemical equilibrium; timescales; experimental studies 相似文献
78.
Caroline von Bernuth 《Geoforum》2007,38(3):545-557
In recent literature, projects are mostly seen as an efficient form of organization which is particularly suited for mastering tasks of high complexity and creativity and adapting to changing economic and institutional conditions. This paper challenges the assumption that inter-firm projects are persistent organizational arrangements of production in the advertising industry and presents a novel argument about the potential threats to forms of project organization in crisis situations. By exploring the cases of Frankfurt/Main and Leipzig (East Germany), we show that the organization of production is substantially affected by periods of economic crisis or political transformation. We demonstrate that inter-firm projects might be replaced by more durable organizational configurations or might not be viewed as viable options in situations of severe rupture. This applies particularly to the cooperative arrangements in the creative process and leads to an organizational paradox. Although creativity is often a pivotal force to gain competitive advantage, the advertising agencies respond to the challenges of crises by reducing cooperation with external partners to a minimum and sometimes fully rely on in-house personnel. This threatens the potential of the respective firms to develop innovative and creative ideas which would enable the firms to acquire new customers and market segments. Instead of trying to overcome crises by focusing on their creative capabilities, many advertising agencies develop a cost-cutting strategy and rely on more durable network-forms of organization instead of inter-firm projects. 相似文献
79.
This paper presents new evidence from the Dhamar highlands, Yemen, of paleohydrologic response to fluctuations in Holocene climate. Stratigraphic, geochemical, and chronological analyses of highland peat and lacustrine deposits contribute to knowledge of the timing of early Holocene moisture changes on the Arabian Peninsula, providing a backdrop to understanding early cultural development in the Arabian highlands. The location of the Dhamar highlands, characterized by intermontane valleys surrounded by the highest mountains on the Arabian Peninsula and adjacent to the Indian Ocean is ideal for examining the influence of the Indian Ocean Monsoon (IOM) on the moisture history of this region. Fluctuations in the lacustrine and paleosol records of the Dhamar highlands reflect both local changes in paleohydrology and regional influences on the Holocene paleoclimatic conditions in southwest Arabia. In addition, a peat deposit with a radiocarbon age of 10,253 – 10,560 cal yr BP documents some of the earliest Holocene high moisture conditions on the Arabian Peninsula. 相似文献
80.