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61.
Reflectivities of uniform and broken layered clouds 总被引:2,自引:0,他引:2
62.
EUGSTER H. P.; ALBEE A. L.; BENCE A. E.; THOMPSON J. B. JR.; WALDBAUM D. R. 《Journal of Petrology》1972,13(1):147-179
The chemical compositions of synthetic paragonite-muscovitepairs were obtained by electron probe microanalysis of run productsprepared hydrothermally at 300, 400, 500, and 600 ?C and 2.07kbar. The microcrystalline run products were dispersed on polishedberyllium rods, and Na, K, and Si were determined simultaneously.Compositions were determined from K/Si and Na/Si ratios referredto standards. Tentative excess thermodynamic mixing properties of paragonite-muscovitecrystalline solutions, based on the two-phase composition dataand on X-ray diffraction data, are represented by the followingthird-order Margules formulation:
which leads to a critical temperature of 833 ?C and a criticalcomposition of 39.0 mole per cent Mu at 2.07 kbar (the criticalphase is probably metastable with respect to alkali feldsparand corundum). These results are quantitatively in agreementwith Iiyama's (1964) ion-exchange data. From relationships amongthe quantities (arctanh s)/s, In r2, and 1/T we obtain criticalconditions which are in good agreement with the above (Tc =829 ?C, N2c = 0.396). The critical curve obtained from the aboveMargules parameters is given by: Tc(?C) = 768.8 + 31.00P(kbar). The above results are complicated by polymorphism and by possiblelack of complete equilibrium between the two-mica synthesisproducts and possible substitution of hydronium for alkalies.We emphasize, therefore, that the phase diagrams and derivedmixing properties should be applied with caution to naturalmuscovite- and paragonite-bearing assemblages. 相似文献
63.
The Petrology of Grospydite Xenoliths from the Zagadochnaya Kimberlite Pipe in Yakutia 总被引:2,自引:1,他引:2
The xenoliths of garnetclinopyroxenedisthene rocks(grospydites and associated kyanite eclogites) from the Zagadochnayakimberlite pipe in Yakutia have been studied in detail. Contraryto previous data, the presence of a continuous range in thepyrope-grossular series of garnets is shown on the basis ofnumerous X-ray data and 17 chemical analyses of garnets. Thisconclusion is confirmed by the study of separate grains withkyanite intergrowths from the kimberlite heavy fraction, whichare present in the kimberlite as the result of destruction ofgrospydite xenoliths, and possible, of garnet-kyanite rocksalso. A close connection of the calcium content in the garnetwith the sodium content in the coexisting clinopyroxes is alsoshown. An increase in the chemical potential of sodium resultsin the stability of the pryoxene-kyanite assemblage insteadof a garnet of intermediate composition (50 percent of grossular).The interval of the miscibility gap between calcium-rich andcalcium-poor garnets is increased in this way. The data of chemicalanalyses of 14 pyroxenes from the xenoliths indicate that theydiffer in the high aluminium and sodium content from other pyroxenesof eclogite-facies rocks. Chromium-rich bands with a high chromiumcontent in coexisting garnet, pyroxene, and kyantic have beenoccasionally found in the xenoliths. A study has been made ofthe chrome-kyanite with 12.86 per Cr202. The presence of chromium-richminerals in the grospydite xenoliths confrms their connectionwith ultrabasic rocks. 相似文献
64.
Air photo interpretation along with limited field work is the basis of a compilation map of Tertiary structures in the Upper Paleozoic through Mesozoic platform cover strata of Nordenskiold Land. Permian Kapp Starostin Formation strata form a continuous marker horizon delineating both a large NE-verging fold complex, which involves the basement (Hecla Hoek sequence) through basal Tertiary strata, and somewhat smaller scale folds, some of which may have formed in association with detachments and thrusts within the platform cover sequence. The map pattern is both a function of local structural plunge and changes in fold geometry along strike. Regional considerations suggest that subsurface basement-involved thrusts exist. In S Nordenskiold Land, to the E of folded Kapp Starostin Formation strata, a 3.5 km wide zone of folding and thrusting in Triassic and Jurassic strata above a subhorizontal decollement is inferred to occur. Further E is the W limb of the central Tertiary basin syncline. 相似文献
65.
Detecting genotoxicity using the Comet assay following chronic exposure of Manila clam Tapes semidecussatus to polluted estuarine sediments 总被引:1,自引:0,他引:1
Coughlan BM Hartl MG O'Reilly SJ Sheehan D Morthersill C van Pelt FN O'Halloran J O'Brien NM 《Marine pollution bulletin》2002,44(12):1359-1365
Sediments frequently cause damage to biota due to the accumulation of toxic compounds and the bioavailability of sediment-bound contaminants. Damage can be assessed using biomarkers, such as the degree of genotoxic impact following in vivo exposure to pollutants. Genotoxic damage, expressed as single-strand DNA breaks, was measured in cells isolated from haemolymph, gill and digestive gland from the clam Tapes semidecussatus, using the single cell gel electrophoresis (Comet assay). Clams were exposed for three weeks to sediment samples collected from a polluted site and a ‘clean’ reference site.
The level of DNA damage was assessed using an image analysis package and expressed as Tail Moment. Throughout the study, significant differences in DNA damage were recorded for each tissue type between clams exposed to the two sediment samples. We conclude that the Comet assay is a useful tool for the detection of DNA damage in clams chronically exposed to polluted sediments. 相似文献
66.
67.
Improved surface-based geophysical technologies that are commercially available provide a new level of detail that can be used to guide ground water remediation. Surface-based multielectrode resistivity methods and tomographic seismic refraction techniques were used to image to a depth of approximately 30 m below the surface at the Natural and Accelerated Bioremediation Research Field Research Center. The U.S. Department of Energy (DOE) established the research center on the DOE Oak Ridge Reservation in Oak Ridge, Tennessee, to conduct in situ field-scale studies on bioremediation of metals and radionuclides. Bioremediation studies are being conducted on the saprolite, shale bedrock, and ground water at the site that have been contaminated with nitrate, uranium, technetium, tetrachloroethylene, and other contaminants (U.S. DOE 1997). Geophysical methods were effective in imaging the high-ionic strength plume and in defining the transition zone between saprolite and bedrock zones that appears to have a significant influence on contaminant transport. The geophysical data were used to help select the location and depth of investigation for field research plots. Drilling, borehole geophysics, and ground water sampling were used to verify the surface geophysical studies. 相似文献
68.
Kilemade M Hartl MG Sheehan D Mothersill C van Pelt FN O'Brien NM O'Halloran J 《Marine pollution bulletin》2004,49(11-12):1084-1096
Surface sediment from three polluted sites within Cork Harbour, Ireland, and from a relatively clean reference site were collected and analysed for polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), brominated flame retardants (BFRs), organotins (OTs), and heavy metals. PAHs were determined to be the most abundant class of contaminant. Concentrations of the sum (Sigma) of the 21 PAHs measured from the Harbour sites (2877.70 ng g(-1), 1000.7 ng g(-1) and 924.40 ng g(-1) dry weight respectively) were significantly higher than that of the sediment from the reference site (528.30 ng g(-1) dry weight). An inner harbour site, Douglas being the more contaminated of the three harbour sites. A similar pattern was observed with the other contaminants however, these compounds, with the exception of the heavy metals, all tended to be detected at concentrations on or below detection limits. 相似文献
69.
70.
Chemical analyses for the following amphibole pairs are presented:anthophyllitetremolite (or actinolite, or hornblende),cummingtonite (or grunerite)actinolite (or hornblende),cummingtonite (or grunerite)anthophyllite (or gedrite),and manganoan cummingtonitemagnesioriebeckite. Nineteen analyses of such pairs are quoted from the literature,and thirty-seven additional pairs have been newly analyzed byelectron probe techniques. Quantitative microprobe determinationsof Si, Al, Fe, Mn, Mg, Ca, and Na were made on polished thin-sections,using naturally occurring, analyzed, homogeneous amphibolesas standards. The literature analyses and the electron probeanalyses for metamorphic, two-amphibole assemblages are givenfor amphiboles in physical contact, which show no textural evidenceof one amphibole being a reaction or alteration product of theother. The chemical data for some of the volcanic, twoamphiboleassemblages were obtained from occurrences that probably donot represent equilibrium pairs. The chemical data are used to determine the extent of the miscibilitygaps between the various amphibole series and the fractionationof the major elements between the two amphiboles of a pair.Anthophyllite and members of the cummingtonite-grunerite seriesgenerally have a larger Fe(total)/Mg ratio than the coexistingcalcic amphibole. The maximum CaO, Al2O3and Na2O contents ofcummingtonite in metamorphic cummingtonitehornblendepairs are 19 and 32, 02 weight per cent, respectively. Themaximum CaO, A12O3, and Na2O contents of cummingtonite in metamorphiccummingtonite-hornblende pairs are 19, 32, and 02 weightper cent, respectively. Larger CaO and Al2O3 values reportedin the literature were found to be too high because of admixtureof actinolite or hornblende in the analyzed separates. Smallamounts of MnO tend to concentrate preferentially in anthophylliteor cummingtonite of anthophyllite-hornblende and cummingtonite-hornblendepairs. Anthophyllite-cummingtonite pairs may show very similarFe(total)/Mg ratios and differ slightly in Al2O3 content only. 相似文献