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A method for computing and displaying the temporal variation of rotary spectral estimates is described. The method is applied to time series measurements of highly nonstationary winds and currents. The results indicate approximately fortnightly modulation of diurnal wind energy and inertial current energy. 相似文献
44.
Watson and Nguyen (1985) and Watson (1987) consider the problem of plotting confidence regions in a ternary diagram, for a trinomial probability vector , based on Pearson's x2. Their results are extended to the power-divergence family of statistics resulting in confidence regions of diverse shapes and sizes. The members of the family with the most accurate coverage probabilities are =2/3 and =1/2. 相似文献
45.
Longxiang Ye Dayu Zhang Shiwei Wang Taofa Zhou Feng Yuan Noel C. White Wenjiao Xiao 《Resource Geology》2022,72(1):e12269
The Baishan molybdenum deposit is located in the central part of the Eastern Tianshan-Beishan tectonic belt, NW China. The deposit is hosted in early Carboniferous Gandun Formation biotite-rich hornfels and is genetically related to unexposed granodiorite porphyry beneath the orebodies. The molybdenite occurs in three different types from early to late stage: Molybdenite - Fe-Cu-sulfides - K-feldspar - quartz veins (Group 1); Molybdenite - Fe-Cu-sulfides - quartz veins (Group 2); and disseminated molybdenite in the wall rock (Group 3). Rhenium concentrations in the molybdenite grains range from 108 to 277 ppm in Group 1, 69–121 ppm in Group 2 and 46–135 ppm in Group 3. The Re concentrations of molybdenite in the Baishan Mo deposit decrease from early to late and from the center to periphery, and molybdenite types vary from the 2H1 poly-type in Groups 1 and 2 to the 2H1 + 3R2H1 poly-type in Group 3, based on X-ray diffraction results. The Re-enriched molybdenite probably formed from an oxidized magmatic fluid that separated from a highly oxidized and H2O- and volatile-enriched adakitic intrusion generated in the lower crust. 相似文献
46.
The Samgwang mine is located in the Cheongyang gold district (Cheonan Metallogenic Province) of the Republic of Korea. It
consists of eight massive, gold-bearing quartz veins that filled NE- and NW-striking fractures along fault zones in Precambrian
granitic gneiss of the Gyeonggi massif. Their mineralogy and paragenesis allow two separate vein-forming episodes to be recognized,
temporally separated by a major faulting event. The ore minerals occur in quartz and calcite of stage I, associated with fracturing
and healing of veins. Hydrothermal wall-rock alteration minerals of stage I include Fe-rich chlorite (Fe/(Fe+Mg) ratios 0.74-0.81),
muscovite, illite, K-feldspar, and minor arsenopyrite, pyrite, and carbonates. Sulfide minerals deposited along with electrum
during this stage include arsenopyrite, pyrite, pyrrhotite, sphalerite, marcasite, chalcopyrite, galena, argentite, pyrargyrite,
and argentian tetrahedrite. Only calcite was deposited during stage II. Fluid inclusions in quartz contain three main types
of C–O–H fluids: CO2-rich, CO2–H2O, and aqueous inclusions. Quartz veins related to early sulfides in stage I were deposited from H2O–NaCl–CO2 fluids (1,500–5,000 bar, average 3,200) with T
htotal values of 200°C to 383°C and salinities less than about 7 wt.% NaCl equiv. Late sulfide deposition was related to H2O–NaCl fluids (140–1,300 bar, average 700) with T
htotal values of 110°C to 385°C and salinities less than about 11 wt.% NaCl equiv. These fluids either evolved through immiscibility
of H2O–NaCl–CO2 fluids as a result of a decrease in fluid pressure, or through mixing with deeply circulated meteoric waters as a result
of uplift or unloading during mineralization, or both. Measured and calculated sulfur isotope compositions (δ34SH2S = 1.5 to 4.8‰) of hydrothermal fluids from the stage I quartz veins indicate that ore sulfur was derived mainly from a magmatic
source. The calculated and measured oxygen and hydrogen isotope compositions (δ18OH2O = −5.9‰ to 10.9‰, δD = −102‰ to −87‰) of the ore-forming fluids indicate that the fluids were derived from magmatic sources
and evolved by mixing with local meteoric water by limited water–rock exchange and by partly degassing in uplift zones during
mineralization. While most features of the Samgwang mine are consistent with classification as an orogenic gold deposit, isotopic
and fluid chemistry indicate that the veins were genetically related to intrusions emplaced during the Jurassic to Cretaceous
Daebo orogeny. 相似文献
47.
Climate impacts of recent multidecadal changes in Atlantic Ocean Sea Surface Temperature: a multimodel comparison 总被引:4,自引:4,他引:0
Daniel L. R. Hodson Rowan T. Sutton Christophe Cassou Noel Keenlyside Yuko Okumura Tianjun Zhou 《Climate Dynamics》2010,34(7-8):1041-1058
During the twentieth century sea surface temperatures in the Atlantic Ocean exhibited prominent multidecadal variations. The source of such variations has yet to be rigorously established—but the question of their impact on climate can be investigated. Here we report on a set of multimodel experiments to examine the impact of patterns of warming in the North Atlantic, and cooling in the South Atlantic, derived from observations, that is characteristic of the positive phase of the Atlantic Multidecadal Oscillation (AMO). The experiments were carried out with six atmospheric General Circulation Models (including two versions of one model), and a major goal was to assess the extent to which key climate impacts are consistent between the different models. The major climate impacts are found over North and South America, with the strongest impacts over land found over the United States and northern parts of South America. These responses appear to be driven by a combination of an off-equatorial Gill response to diabatic heating over the Caribbean due to increased rainfall within the region and a Northward shift in the Inter Tropical Convergence Zone (ITCZ) due to the anomalous cross-equatorial SST gradient. The majority of the models show warmer US land temperatures and reduced Mean Sea Level Pressure during summer (JJA) in response to a warmer North Atlantic and a cooler South Atlantic, in line with observations. However the majority of models show no significant impact on US rainfall during summer. Over northern South America, all models show reduced rainfall in southern hemisphere winter (JJA), whilst in Summer (DJF) there is a generally an increase in rainfall. However, there is a large spread amongst the models in the magnitude of the rainfall anomalies over land. Away from the Americas, there are no consistent significant modelled responses. In particular there are no significant changes in the North Atlantic Oscillation (NAO) over the North Atlantic and Europe in Winter (DJF). Additionally, the observed Sahel drying signal in African rainfall is not seen in the modelled responses. Suggesting that, in contrast to some studies, the Atlantic Multidecadal Oscillation was not the primary driver of recent reductions in Sahel rainfall. 相似文献
48.
Juan Argüelles Ricardo Tafur Anatolio Taipe Piero Villegas Friedeman Keyl Noel Dominguez Martín Salazar 《Progress in Oceanography》2008,79(2-4):308
Changes in population structure of the jumbo flying squid Dosidicus gigas in Peruvian waters were studied based on size-at-maturity from 1989 to 2004. From 1989 to 1999, mature squid belonging to the medium-sized group prevailed, but from 2001 on, mature squids were larger. This change is not related to the changes in sea surface temperature and we hypothesized that it was caused by the population increase of mesopelagic fishes as prey. 相似文献
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