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51.
塔里木地台北缘内生磷矿预测及资源远景评价 总被引:5,自引:4,他引:1
塔里木地台北缘深断裂两侧有多处碱性杂岩体分布。通过对其长约2000km范围内地质资料的搜集,实地地质调查,遥感资料解译,航、地磁异常资料的分析与实测工作、重点评价区工程验证等一系列成果的综合分析与研究,发现260km铁磷矿化带,控矿岩体具有“串珠状等距性特征,铁磷矿体主要赋存在辉石岩和黑云母辉石岩中。”在三个调查区中划分出9个找矿远景区。尉犁-兴地调查区中发现多处偏碱性超基性杂岩体,其中三处远景区经深部验证均发现铁磷矿体。是寻找内生磷矿颇具找矿前景的地区。温宿-拜城调查区是寻找Nb-Ta—P矿前景的最佳地段。巴楚-阿图什调查区应是寻找碳酸盐型磷-稀土矿的有利地区。经研究提出:“古老地台边缘受深大断裂控制的偏碱性-超基性杂岩成矿,碱幔分异-碱性偏碱性不混熔岩浆成矿-熔离作用形成层状铁磷矿体的成岩成矿模式”。 相似文献
52.
David W. Dyrssen 《Aquatic Geochemistry》1999,5(1):59-73
The following determinations in the Norwegian fjord Framvaren and the Black Sea have been compared: carbon-14, carbon-13, alkalinity, total dissolved inorganic carbon, sulfide, tritium (HTO), trace metals, silica, ammonium and phosphate. The historical development of the two anoxic basins is quite different. The carbon-14 age of the total inorganic dissolved carbonate in the deep water is 2000 years in the Black Sea, but only 1600 in Framvaren. The fresh water supply and composition are different. The rivers entering the Black Sea have a high alkalinity, but the river input and runoff to Framvaren has a very low alkalinity. The alkalinity, carbonate and sulfide concentrations in the anoxic waters below the chemoclines are much higher in Framvaren. This is mainly an effect of the different surface to volume ratios. The difference in carbon-13 (-8 for the Black Sea deep water, -19 in the Framvaren bottom water) is mainly due to the smaller imprint of the decomposition of organic matter on the Black Sea deep water.The concentration of trace metals in the particulate form are about the same in the deep water. About 76% of the molybdate in seawater is lost in the sulfidic water of Framvaren, and about 82–96% of the molybdate carried into the Black Sea by the Bosporus undercurrent is lost in the deep water. The relation between silica, ammonium and phosphate can be understood if part of the ammonium is being removed by denitrification, a process that most likely has been going on for thousands of years. 相似文献
53.
Scoates James S.; Weis Dominique; Franssens Matthias; Mattielli Nadine; Annell Heidi; Frey Frederick A.; Nicolaysen Kirsten; Giret Andre 《Journal of Petrology》2008,49(1):79-105
The age, petrology, major and trace element geochemistry, andSr–Nd–Hf–Pb isotopic geochemistry of basicand felsic rocks from the Val gabbro plutonic suite on the KerguelenArchipelago, Southern Indian Ocean, are used to constrain thetemporal and compositional relationships between sub-volcanicintrusions and flood basalt volcanism during the formation ofa major oceanic island. The 4 km2 Val gabbro plutonic suitewas emplaced at 24·25 ± 0·15 Ma (U–Pbzircon) into 25 Ma volcanic rocks of the Southeast Province,locally producing a large zone of overlying basaltic breccia.Cumulate basic–ultrabasic rocks are the dominant lithologyin the intrusion, with horizontally layered peridotites at thebase of the exposed part of the intrusion, overlain by verticallylayered, coarse-grained plagioclase-bearing peridotites, melagabbrosand equigranular gabbros. The intrusion was formed by repeatedinjections of relatively crystal-rich and crystal-poor magmasinto an open-system magma reservoir. Strong geochemical andisotopic similarities between the fine-grained marginal microgabbrosand cross-cutting felsic rocks and the hosting mildly alkalicbasalts and trachytes of the Southeast Province indicate thatthey were derived from similar alkalic basaltic parental magmas,which were dominated by the enriched component of the Kerguelenmantle plume source. At 25 Ma, the change from tholeiitic–transitionalto mildly alkalic basalts marks the terminal stage of floodbasalt volcanism on the Kerguelen Archipelago. This compositionalchange was associated with deeper melting within the Kerguelenplume source, lower extents of melting, a decrease in magmasupply, and the emplacement of high-level intrusions such asthe Val gabbro plutonic suite. KEY WORDS: Kerguelen Archipelago; Val gabbro plutonic suite; oceanic island; gabbros; sub-volcanic intrusion; alkalinity; Sr–Nd–Hf–Pb isotopes 相似文献
54.
Takashi Midorikawa Sonoki Iwano Kazuhiro Saito Hiroyuki Takano Hitomi Kamiya Masao Ishii Hisayuki Y. Inoue 《Journal of Oceanography》2003,59(6):871-882
We observed the partial pressure of oceanic CO2, pCO2
sea, and related surface properties in the westernmost region of the subarctic North Pacific, seasonally from 1998 to 2001. The
pCO2
sea in the Oyashio region showed a large decrease from winter to spring. In winter, pCO2
sea was higher than 400 μatm in the Oyashio region and this region was a source of atmospheric CO2. In spring, pCO2
sea decreased to extremely low values, less than 200 μatm (minimum, 139 μatm in 2001), around the Oyashio region with low surface
salinity and this region turned out to be a strong sink. The spatial variations of pCO2
sea were especially large in spring in this region. The typical Oyashio water with minimal mixing with subtropical warm water
was extracted based on the criterion of potential alkalinity. The contribution of main oceanic processes to the changes in
pCO2
sea from winter to spring was estimated from the changes in the concentrations of dissolved inorganic carbon and nutrients, total
alkalinity, temperature and salinity observed in surface waters in respective years. These quantifications indicated that
photosynthesis made the largest contribution to the observed pCO2
sea decreases in all years and its magnitude was variable year by year. These year-to-year differences in spring biological contribution
could be linked to those in the development of the density stratification due to the decrease in surface salinity. Thus, the
changes in the surface physical structure could induce those in pCO2
sea in the Oyashio region in spring. Furthermore, it is suggested that the direction and magnitude of the air-sea CO2 flux during this season could be controlled significantly by the onset time of the spring bloom.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
55.
56.
Summertime freshwater fractions in the surface water of the western Arctic Ocean evaluated from total alkalinity 总被引:2,自引:0,他引:2
As a quasi-conservative tracer, measures of total alkalinity (TA) can be utilized to trace the relative fractions of freshwater and seawater. In this study, based on the TA and related data collected during the third Chinese National Arctic Research Expedition (JulySeptember 2008, 3rd CHINARE-Arctic) and the fourth Chinese National Arctic Research Expedition (JulySeptember 2010, 4th CH1NARE-Arctic), fractions of sea-ice meltwater, river runoff, and seawater within the surface water of the western Arctic Ocean were determined using salinil~~ and TA relationships. The largest fraction of seeL-ice meltwater was found around 75~N within the Canada Basin during both surveys, which is located at the ice edge. Generally, it was found that the frac- tion of river runoff was less than that of sea-ice meltwater. The river runoff, composed mainly of contributions from the Yukon River carried by Bering inflow water and the Mackenzie River, was influenced by the currents, leading to two peak areas of its fraction. Our results show that the dilution effect of freshwater carried by Bering inflow water during the 3rd CH1NARE-Arctic in 2008 expedition period may be stronger than that during the 4th CH1NARE-Arctic in 2010 expedition period. The peak area of sea-ice meltwater fraction during the 4th CH1NARE-Arctic was different from that of the 3rd CHINAR-E-Arctic, corresponding to their sea-ice condition. 相似文献
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60.
对于高硅、高铝、高铁等类的酸性样品,在熔融制样时,通过加入碱性氧化物来提高熔融体的碱性,消除酸性熔融体的不熔物,提高熔融体的流动性,使熔融体混和均匀,提高了制样的重现性,使准确度得到了提高。 相似文献