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81.
Niranjan D. Chatterjee Klaus Miller Walter Olbricht 《Physics and Chemistry of Minerals》1994,21(1-2):50-62
Internally consistent thermodynamic data, including their uncertainties and correlations, are reported for 22 phases of the quaternary system CaO-Al2O3-SiO2-H2O. These data have been derived by simultaneous evaluation of the appropriate phase properties (PP) and reaction properties (RP) by the novel technique of Bayes estimation (BE). The thermodynamic model used and the theory of BE was expounded in Part I of this paper. Part II is the follow-up study illustrating an application of BE. The input for BE comprised, among others, the a priori values for standard enthalpy of formation of the i-th phase, Δf H i 0 , and its standard entropy, S i 0 , in addition to the reaction reversal constraints for 33 equilibria involving the relevant phases. A total of 269 RP restrictions have been processed, of which 107 turned out to be non-redundant. The refined values for Δf H i 0 and S i 0 obtained by BE, including their 2σ-uncertainties, appear in Table 4; the Appendix reproduces the corresponding correlation matrix. These data permit generation of computed phase diagrams with 2σ-uncertainty envelopes based on conventional error propagation; Fig. 3 depicts such a phase diagram for the system CaO-Al2O3-SiO2. It shows that the refined dataset is capable of yielding phase diagrams with uncertainty envelopes narrow enough to be geologically useful. The results in Table 4 demonstrate that the uncertainties of the prior values for Δf H i Emphasis>0 , given in Table 1, have decreased by up to an order of magnitude, while those for S i 0 improved by a factor of up to two. For comparison, Table 4 also lists the refined Δf H i 0 and S i 0 data obtained by mathematical programming (MAP), minimizing a quadratic objective function used earlier by Berman (1988). Examples of calculated phase diagrams are given to demonstrate the advantages of BE for deriving internally consistent thermodynamic data. Although P-T curves generated from both MAP and BE databases will pass through the reversal restrictions, BE datasets appear to be better suited for extrapolations beyond the P-T range explored experimentally and for predicting equilibria not constrained by reversals. 相似文献
82.
Chemical degradations of coal resins, coal asphaltenes and coal residues have been performed with selective, non-oxidative reagents. The coal comprise samples a rank interval 0.30–1.21 %Rm. Degraded low-molecular-weight compounds were analyzed by GC-MS. The distributions of pentacyclic terpanes, isoprenoids, n-alkanes, acids and alcohols obtained as degradation products illustrate a considerable variability between the macromolecular coal fractions. A structural study on the molecular level of the degraded compounds from coal resins and coal asphaltenes show their potential to generate hydrocarbons during coalification process. 相似文献
83.
Walter Riesen Heinz Gamsjäger Paul W. Schindler 《Geochimica et cosmochimica acta》1977,41(9):1193-1200
The carbonato and hydrogencarbonato complexes of Mg2+ were investigated at 25 and 50° in solutions of the constant ClO4? molality (3 M) consisting preponderantly of NaClO4. The experimental data could be explained assuming the following equilibria: Mg2+ + CO2B + H2O ag MgHCO+3 + H+, , Mg2+ + 2 CO2g + 2 H2Oag Mg(HCO3)02 ± 2 H+, , ?15.37 ± 0.39 (50°), Mg2+ + CO2g + H2Oag MgCO03 + 2 H+, ,?15.23 ± 0.02 (50°), with the assumption γMgCO30 = γMg(HCO3)02, ΔG0(I = 0) for the reaction MgCO03 + CO2g + H2O = Mg(HCO3)02 was estimated to be ?3.91 ± 0.86 and 0.6 ± 2.4 kJ/mol at 25 and 50°C, respectively. The abundance of carbonate linked Mg(II) species in fresh water systems is discussed. 相似文献
84.
Walter E. Reed 《Geochimica et cosmochimica acta》1977,41(9):1231-1245
Modern sediments of Mono Lake show marked variation in lipid composition with depositional environment. Constituents derived from the drainage basin, characterized by high molecular weight alkane hydrocarbons (C25–C31), and the steroids β-sitosterol and brassicasterol, predominate in near-shore environments. In the deepest part of the lake, sediments exhibit a combination of externally-derived constituents, and lipids derived from the lake biota; the latter characterized by low molecular-weight alkanes and alkenes (C15–C17), phytane, and the steroids ergost-7-en-3β-ol and 24-ethylcholest-7-en-3-β-ol. Steranes, 4-methylsteranes, and the C18 and C19 isoprenoids appear to be forming in the intensely reducing bottom sediments at the present time.The compositions of samples from the Pleistocene succession of Mono Basin suggest that sample-to-sample variation within the same stratum is negligible so long as unweathered samples from the same depositional environment are compared. Sediments having equivalent lithologies may or may not have similar compositions, but sediments having similar fossil contents do show similar lipid compositions. Subaerial weathering of sediments causes a marked decrease in the amount of extractable organic material, as well as distinct changes in its hydrocarbon composition. Specifically, weathered sediments exhibit a decrease in relative content of low molecular weight hydrocarbons and a relative increase in nC22.Organic composition of sediments from the Pleistocene stratigraphie column cannot be correlated with depth of burial. Compositional changes with stratigraphie position are probably related to paleo-ecological factors such as population or productivity rather than depth of burial. Lithology and organic composition provide mutually-corroborating evidence regarding glacial advances in the adjacent Sierra Nevada Mountains. During glaciations, the lake sediments are rich in sandstones, and the organic composition shows a predominance of externally-derived debris, with no evidence for contributions from the lake biota. 相似文献
85.
86.
H. de Almeida Sampaio Filho G. P. Sighinolfi E. Galli 《Contributions to Mineralogy and Petrology》1973,38(4):279-290
Chemical analyses and crystallographic and some optical data have been obtained for 28 samples of beryl from Bahia State, Brazil. The larger range of variability in the chemical composition is shown by Mg, Fe and Li. Sodium is the more diffuse alkali element. Potassium is always very limited. Calcium appears in noticeable amounts only in three samples. The Ti, Cr, Rb, and Cs elements were also tested. The samples studied here can be defined as sodium-potassium beryls with low alkali content. Unit cell parameters show the following ranges: a=9.210–9.245 and c=9.190–9.220 Å. From a statistical analysis of these data it may be seen that: an increase of Fe and (Fe+Mn+Mg) percentage has a positive correlation with a, but no influence on c, which in turn has a close positive correlation with Li and is negatively correlated with Be. Less negative correlations also exist between the pairs {Be, Li}, {a,Al}, {Al, Fe} and {Al, (Fe+Mn+Mg)}. A positive correlation also exists between sodium and the parameter a. 相似文献
87.
Walter Müller 《Pure and Applied Geophysics》1967,66(1):169-182
Zusammenfassung Nach allgemeinen und quantitativen Angaben über die Ursachen der Zu-und Abnahmen der Kondensationskerndichte wird auf die natürliche und industrielle Kernproduktion verwiesen. Auf Grund einjähriger Morgen- und Mittagsbeobachtungen in Wien mit einem Pollak-Kondensationskernzähler wird besonders die Sedimentation, der Washout- und Rainouteffekt, der Einfluss von Austausch und Windadvektion sowie der Jahres- und Wochengang besprochen.
Summary General as well as quantitative details of reasons of the variations of the density of condensation nuclei is mentioned. Based on one year's records of observations in the morning and at noon in Vienna, executed by menas of a Pollak-condensation nucleus counter especially the effects of sedimentation, washout, rainout, exchange, wind advection, annual and weekly variation is discussed.相似文献
88.
Walter Weingart 《International Journal of Earth Sciences》1955,44(1):173-192
Zusammenfassung Stratigraphische und tektonische Untersuchungen im Gebiet zwischen Rheinbrohl/Brohl im NW und Leutesdorf/Namedy im SE erbrachten den Nachweis einer Großmulde aus Mittleren Siegener Schichten, deren Kern bei Oberhammerstein den Rhein quert. Die HENKE'sche Annahme eines Hönningen-Seifener Sattels im NW unseres Gebietes konnte bestätigt werden. Aus dem gegenseitigen Verhalten zwischen Faltung und Brüchen verschiedener Art ließ sich eine Altersfolge entwickeln, wobei die Einzelphasen sich einander zeitlich überschneidend ablösen. Diese zeitliche Folge wird von Falte zu Falte von den örtlichen Faktoren modifiziert, so durch die Verzopfung zweier Einzelfalten, wie an einem gut überschaubaren Beispiel gezeigt wird. 相似文献
89.
During the last two decades, there has been growing interest in the integration of existing ideas and data to produce new
synthetic models and hypotheses leading to discovery and advancement in estuarine and coastal science. This essay offers an
integrated definition of what is meant by synthesis research and discusses its importance for exploiting the rapid expansion
of information availability and for addressing increasingly complex environmental problems. Approaches and methods that have
been used in published synthetic coastal research are explored and a list of essential steps is developed to provide a foundation
for conducting synthetic research. Five categories of methods used widely in coastal synthesis studies are identified: (1)
comparative cross-system analysis, (2) analysis of time series data, (3) balance of cross-boundary fluxes, (4) system-specific
simulation modeling, and (5) general systems simulation modeling. In addition, diverse examples are used to illustrate how
these methods have been applied in previous studies. We discuss the urgent need for developing curricula for classroom and
experiential teaching of synthesis in coastal science to undergraduate and graduate students, and we consider the societal
importance of synthetic research to support coastal resource management and policy development. Finally, we briefly discuss
the crucial challenges for future growth and development of synthetic approaches to estuarine and coastal research. 相似文献
90.
Walter Stephan 《International Journal of Earth Sciences》1959,48(1):92-95
Zusammenfassung Auswirkungen der saalischen Phase sind nun auch im Stockheimer Becken erstmals festgestellt. In der Hauptsache ist in diesem Gebiet jedoch mit orogenetischen Bewegungen im Unterrotliegenden selbst zu rechnen. — Der Vulkanismus entwickelte sich im Becken bzw. an seinen Rändern vermutlich bereits im jüngsten Oberkarbon (1. Phase, am stärksten ausgebildet) und hält dann im Unterrotliegenden an (2. Phase, evtl. noch Gehrener Stufe). Aus dem mittleren Rotliegenden sind bisher nur Porphyr-Fanglomerate angeführt worden. Allerdings muß berücksichtigt werden, daß deren Neubearbeitung noch nicht abgeschlossen ist und das Stockheimer Becken ohnehin nur einen kleinen Ausschnitt aus der Gesamtentwicklung am Südwestrand des Frankenwaldes darstellt. Mit einem Vulkanismus im mittleren Rotliegenden (3. Phase, ? Goldlauterer Stufe) ist demnach auch hier noch zu rechnen. 相似文献