全文获取类型
收费全文 | 121篇 |
免费 | 5篇 |
国内免费 | 3篇 |
专业分类
测绘学 | 3篇 |
大气科学 | 52篇 |
地球物理 | 7篇 |
地质学 | 22篇 |
海洋学 | 5篇 |
天文学 | 37篇 |
自然地理 | 3篇 |
出版年
2020年 | 1篇 |
2019年 | 4篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 5篇 |
2015年 | 1篇 |
2014年 | 13篇 |
2013年 | 2篇 |
2012年 | 2篇 |
2011年 | 4篇 |
2010年 | 6篇 |
2009年 | 7篇 |
2008年 | 3篇 |
2007年 | 4篇 |
2006年 | 6篇 |
2005年 | 2篇 |
2004年 | 3篇 |
2003年 | 4篇 |
2002年 | 2篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1968年 | 2篇 |
1963年 | 1篇 |
1960年 | 1篇 |
1958年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有129条查询结果,搜索用时 15 毫秒
21.
Elmar Träbert 《Monthly notices of the Royal Astronomical Society》1998,297(2):399-404
A number of electric dipole transitions from low-lying long-lived levels in Si-, P- and S-like ions of Fe and neighbouring elements have been identified by their longevity in delayed EUV spectra after foil excitation of fast ion beams. Some of these new identifications pertain to previously unidentified lines in solar flare spectra. 相似文献
22.
23.
Martin SCHMIEDER Elmar BUCHNER Winfried H. SCHWARZ Mario TRIELOFF Philippe LAMBERT 《Meteoritics & planetary science》2010,45(8):1225-1242
Abstract– 40Ar/39Ar dating of potassium feldspar (primary spherulitic‐blocky and secondary idiomorphic K‐feldspar) separated from impact‐metamorphosed gneiss found near Videix in the western central part of the Rochechouart impact structure (NW Massif Central, France) yielded a Rhaetian combined age of 201 ± 2 Ma (2σ), indistinguishable within uncertainty from the age of the Triassic/Jurassic boundary. Ballen quartz intergrown with the primary K‐feldspar indicates post‐shock temperatures exceeding approximately 1000 °C that affected the precursor gneiss. Geochemically, both feldspar types represent essentially pure potassium end‐members. Apart from the approximately 15 km diameter impact deposit area, the youngest crystallization age known for basement rocks in this part of the Massif Central is approximately 300 Ma. No endogenic magmatic‐thermal events are known to have occurred later in this region. The K‐feldspar recrystallized from local feldspar melts and superimposed post‐shock hydrothermal crystallization, probably within some thousands of years after the impact. It is, therefore, suggested that the 40Ar/39Ar age for the Videix gneiss (as a potassic “impact metasomatite”) dates the Rochechouart impact, in consistence with evidence for K‐metasomatism in the Rochechouart impactites. The new age value is distinctly younger than the previously obtained Karnian–Norian age for Rochechouart and, thus, contradicts the Late Triassic multiple impact theory postulated some years ago. In agreement with the paleogeographic conditions in the western Tethys domain around the Triassic/Jurassic boundary, the near‐coastal to shallow marine Rochechouart impact is compatible with the formation of seismites and tsunami deposits in the latest Triassic of the British Isles and possible related deposits in other parts of Europe. 相似文献
24.
Elmar BUCHNER Winfried H. SCHWARZ Martin SCHMIEDER Mario TRIELOFF 《Meteoritics & planetary science》2010,45(4):662-674
Abstract– 40Ar/39Ar dating of recrystallized K‐feldspar melt particles separated from partially molten biotite granite in impact melt rocks from the approximately 24 km Nördlinger Ries crater (southern Germany) yielded a plateau age of 14.37 ± 0.30 (0.32) Ma (2σ). This new age for the Nördlinger Ries is the first age obtained from (1) monomineralic melt (2) separated from an impact‐metamorphosed target rock clast within (3) Ries melt rocks and therewith extends the extensive isotopic age data set for this long time studied impact structure. The new age goes very well with the 40Ar/39Ar step‐heating and laser probe dating results achieved from mixed‐glass samples (suevite glass and tektites) and is slightly younger than the previously obtained fission track and K/Ar and ages of about 15 Ma, as well as the K/Ar and 40Ar/39Ar age data obtained in the early 1990s. Taking all the 40Ar/39Ar age data obtained from Ries impact melt lithologies into account (data from the literature and this study), we suggest an age of 14.59 ± 0.20 Ma (2σ) as best value for the Ries impact event. 相似文献
25.
Based on a large number of energy-economic and integrated assessment models, the Energy Modeling Forum (EMF) 27 study systematically explores the implications of technology cost and availability for feasibility and macroeconomic costs of energy system transformations toward climate stabilization. At the highest level, the technology strategy articulated in all the scenarios in EMF27 includes three elements: decarbonization of energy supply, increasing the use of low-carbon energy carriers in end-use, and reduction of energy use. The way that the scenarios differ is in the degree to which these different elements of strategy are implemented, the timing of those implementations, and the associated macroeconomic costs. The study also discusses the value of individual technologies for achieving climate stabilization. A robust finding is that the unavailability of carbon capture and storage and limited availability of bioenergy have the largest impact on feasibility and macroeconomic costs for stabilizing atmospheric concentrations at low levels, mostly because of their combined ability to remove carbon from the atmosphere. Constraining options in the electric sector such as nuclear power, wind and solar energy in contrast has a much smaller impact on the cost of mitigation. 相似文献
26.
27.
Alexander Deutsch Christian Koeberl Joel D. Blum Bevan M. French Billy P. Glass Richard Grieve Peter Horn Elmar K. Jessberger Gero Kurat Wolf Uwe Reimold Jan Smit Dieter Stöffler Stuart Ross Taylor 《地学学报》1994,6(6):644-650
In a recent article in Terra Nova, Kristan-Tollmann and Tollmann (1994) suggested that the Biblical Flood can be explained by seven fragments of a comet that impacted the ocean at seven locations on Earth at 03.00h (C.E.T.) on 23 September, 9545 yr BP. We demonstrate that all the ‘geological proofs’ that allegedly support their conclusions are not supported by the available data on impact cratering. Their hypothesis is based on insufficient and ambiguous data, selective citation, and incomplete comprehension of previous research. 相似文献
28.
Elmar K. Jessberger 《Meteoritics & planetary science》1988,23(3):233-234
Abstract— 40Ar-39Ar dating of a strongly shocked, vesiculated gneiss clast in a breccia from the Haughton impact structure yields an isochron age of 23.4 ± 1.0 Ma. The sample contains excess 40Ar. 相似文献
29.
Sensitivity Analysis of Emissions Corridors for the 21st Century 总被引:1,自引:1,他引:0
We investigate the sensitivity of emissions corridors for the 21st century to various factors that are currently under debate in the climate change arena. Emissions corridors represent the range of admissible emissions futures that observe some predefined guardrails on the future development of the human-climate system. They are calculated on the conceptual and methodological basis of the tolerable windows approach. We assess the sensitivity of the corridors to the choice of time-resolved as well as intertemporally aggregated guardrails that exclude an intolerable amount of climate change on the one hand and unbearable mitigation burdens on the other. In addition, we investigate the influence of climate sensitivity on the corridors.Results show a large dependence of emissions corridors on the choice of guardrails and the value of climate sensitivity T
2CO
2. If the guardrail on climate change is specified in terms of a maximum admissible global mean temperature increase T
max to be observed at any time, the size of the corridors is predominantly determined by a climate impact resilience parameter =T
max/T
2CO
2. As is varied from values below 0.5 to values above 1.5, we move from cases where no emissions profile whatsoever can observe all guardrails, to cases where no significant emissions reduction seems necessary given the range of emissions scenarios for the 21st century. The limits on admissible mitigation efforts influence predominantly the timing and the economic viability of emissions reductions. A large mitigation flexibility allows for wait then run emissions paths, while low flexibility asks for a significantly more prudent approach. 相似文献
30.
Towards a better understanding of magnesium-isotope ratios from marine skeletal carbonates 总被引:2,自引:0,他引:2
Dorothee Hippler Dieter Buhl Detlev K. Richter 《Geochimica et cosmochimica acta》2009,73(20):6134-2836
This study presents magnesium stable-isotope compositions of various biogenic carbonates of several marine calcifying organisms and an algae species, seawater samples collected from the western Dutch Wadden Sea, and reference materials. The aim of this study is to explore the influence of mineralogy, taxonomy and environmental factors (e.g., seawater isotopic composition, temperature, salinity) on magnesium-isotopic (δ26Mg) ratios of skeletal carbonates. Using high-precision multi-collector inductively coupled plasma mass spectrometry, we observed that the magnesium-isotopic composition of seawater from the semi-enclosed Dutch Wadden Sea is identical to that of open marine seawater. We further found that a considerable component of the observed variability in δ26Mg values of marine skeletal carbonates can be attributed to differences in mineralogy. Furthermore, magnesium-isotope fractionation is species-dependent, with all skeletal carbonates being isotopically lighter than seawater. While δ26Mg values of skeletal aragonite and high-magnesium calcite of coralline red algae indicate the absence or negligibility of metabolic influences, the δ26Mg values of echinoids, brachiopods and bivalves likely result from a taxon-specific level of control on Mg-isotope incorporation during biocalcification. Moreover, no resolvable salinity and temperature effect were observed for coralline red algae and echinoids. In contrast, Mg-isotope data of bivalves yield ambiguous results, which require further validation. The data presented here, point to a limited use of Mg isotopes as temperature proxy, but highlight the method’s potential as tracer of seawater chemistry through Earth’s history. 相似文献