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311.
The period changes of six eclipsing binaries have been studied with focus on the light-time effect. With the least squares method we also calculated parameters of such an effect and properties of the unresolved body in these systems. With these results we discussed the probability of presence of such bodies in the systems with respect to possible confirmation by another method. In two systems we also suggested the hypothesis of fourth body or magnetic activity for explanation of the "second-order variability" after subtraction of the light-time effect of the third body. 相似文献
312.
Karin Mossberg Sonnek Tomas Mårtensson Ester Veibäck Peter Tunved Håkan Grahn Pontus von Schoenberg Niklas Brännström Anders Bucht 《Natural Hazards》2017,88(3):1565-1590
In this study, we analyse and discuss the possible impacts on the Swedish society of a volcanic eruption on Iceland, emitting ash particles and large quantities of sulphur dioxide. A scenario was developed, based on the historical Laki eruption of 1783–1784, to describe the content of a potential sulphur fog over time in Sweden. Due to its high complexity and the many uncertainties in the underpinning scientific data, the scenario was developed using a cross-disciplinary approach incorporating experts from different scientific fields. An analysis of the impacts of the hazard on human health, environment and technical equipment was then performed and, finally, representatives from national authorities assessed the overall societal challenges in responding to the consequences of a massive volcanic eruption. The analysis shows that it is the peak concentrations of sulphur dioxide and sulphuric acid rather than the longer periods of moderate concentrations that contribute most to the negative consequences for human health and environment. Altogether, three societal challenges were identified: the ability to compile and disseminate relevant information fast enough, to perform continuous measurements of concentrations of different substances in affected areas and to meet the large demand for medical care. 相似文献
313.
There is a rich empirical literature testing whether per capita carbon dioxide emissions tend to converge over time and across countries. This article provides a meta-analysis of the results from this research, and discusses how carbon emissions convergence may be understood in, for instance, the presence of international knowledge spillovers and policy convergence. The results display evidence of either divergence or persistent gaps at the global level, but convergence of per capita carbon dioxide emissions between richer industrialized countries. However, the results appear sensitive to the choice of data sample and choice of convergence concept, e.g. stochastic convergence versus β-convergence. Moreover, peer-reviewed studies have a higher likelihood of reporting convergence in carbon dioxide emissions compared to non-refereed work.
POLICY RELEVANCE
The empirical basis for an egalitarian rule of equal emissions per capita in the design of global climate agreements is not solid; this supports the need to move beyond single allocation rules, and increase knowledge about the impacts of combined scenarios. However, even in the context of the 2015 Paris Agreement with its emphasis on voluntary contributions and ‘national circumstances’, different equity-based principles could serve as useful points of reference for how the remaining carbon budget should be allocated. 相似文献
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316.
Trace element and isotopic composition of baddeleyite 总被引:3,自引:0,他引:3
Dr. T. Reischmann G. E. Brügmann K. P. Jochum W. A. Todt 《Mineralogy and Petrology》1995,53(1-3):155-164
Summary Baddeleyite from Palabora Igneous Complex, South Africa, is among the purest natural ZrO2 phases. This has been demonstrated by using various methods, i.e. microprobe, neutron activation, spark source and thermal ion mass spectrometry. HfO2 with 1.87% is the only other major component. The concentrations of other HFSE are also relatively high, compared to most other elements, that reach only a few ppm.The REE display a U-shaped pattern that is interpreted to be superimposed by a strongly LREE enriched source component. The high87Sr/86Sr initial of 0.713085 and the negative Ndt of –10.7 prove that this component was LILE enriched for a long time prior to the formation of the Palabora Igneous Complex. These data indicate that the baddeleyite crystallized from a magma which was derived from an enriched mantle reservoir, similar to that involved in the formation of group II kimberlites.
Spurenelemente und Isotopenzusammensetzung von Baddeleyit
Zusammenfassung Baddeleyit vom Palabora Igneous Complex, Südafrika, gehört zu den reinsten natürlichen Vorkommen von ZrO2. Dies wurde durch Analysen mit verschiedenen Methoden wie Mikrosonde, Neutronenaktivierung, Funken- und Thermionenmassenspektrometrie bestätigt. HfO2 ist mit 1.87 die einzige andere Hauptkomponente, auch die Konzentrationen der anderen HFSE sind relativ hoch im Vergleich zu den anderen Elementen, die nur wenige ppm erreichen.Die REE bilden ein U-förmiges Muster, das als Ausdruck einer stark LREE angereicherten Komponente im Ausgangsgestein gedeutet wird. Das hohe87Sr/86Sr-Initialverhältnis von 0.713085 und das negative Ndt von -10.7 belegen, daß diese Komponente über einen langen Zeitraum vor der Bildung des Palabora Igneous Complex angereichert gewesen war. Diese Daten deuten an, da der Baddeleyit aus einem Magma kristallisierte, das aus einem angereicherten Mantelreservoir stammte, ähnlich dem, das bei der Bildung der Gruppe 11 Kimberlite beteiligt war.相似文献
317.
Determination of the Tin Stable Isotopic Composition in Tin‐bearing Metals and Minerals by MC‐ICP‐MS
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Gerhard Brügmann Daniel Berger Ernst Pernicka 《Geostandards and Geoanalytical Research》2017,41(3):437-448
This study uses MC‐ICP‐MS for the precise analysis of the stable tin isotopic composition in ore minerals of tin (cassiterite, stannite), tin metal and tin bronze. The ultimate goal is to determine the provenance of tin in ancient metal objects. We document the isotope compositions of reference materials and compare the precision of different isotope ratios and the accuracy of different procedures of mass fractionation correction. These data represent a base with which isotopic data of future studies can be directly compared. The isotopic composition of cassiterite and stannite can be determined after reduction to tin metal and bronze, respectively. Both metals readily dissolve in HCl, but while the solutions of tin metal can be directly measured, the bronze solutions must be purified with an anion exchanger. The correction of the mass bias is best performed with an internal Sb standard and an empirical regression method. A series of Sn isotope determinations on commercially available mono‐element Sn solutions as well as reference bronze materials and tin minerals show fractionations ranging from about ?0.09‰ to 0.05‰/amu. The combined analytical uncertainty (2s) was determined by replicate dissolutions of reference materials of bronze (BAM 211, IARM‐91D) and averages at about 0.005‰/amu. 相似文献
318.
Rudolf Brázdil 《GeoJournal》1994,32(3):199-205
On the basis of documentary evidence, proxy-data and instrumental observations, the climatic fluctuation during the last millennium in the Czech Lands is analysed. According to narrative sources, the warmest period falls between the 1260s–1380s, documents for Lamb's (1984) Medieval Warm Epoch in 1150–1300 are missing. The prevalence of extremely cold and also rainy periods, as an expression of the Little Ice Age, is most conspicuous in the 15th century, in the 1590s and, with three interruptions, between the 1730s–1850s. Since the latter half of the 19th century a rising temperature trend has manifested itself. A regional climatic scenario for the model of global warming is discussed in relation to the observed trends in the Czech Lands. 相似文献