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排序方式: 共有116条查询结果,搜索用时 46 毫秒
81.
Surface Acidity of Amorphous Aluminum Hydroxide 总被引:3,自引:0,他引:3
K. FUKUSHI K. TSUKIMURA H. YAMADA 《《地质学报》英文版》2006,80(2):206-211
The surface acidity of synthetic amorphous AI hydroxide was determined by acid/base titration with several complementary methods including solution analyses of the reacted solutions and XRD characterization of the reacted solids. The synthetic specimen was characterized to be the amorphous material showing four broad peaks in XRD pattern. XRD analyses of reacted solids after the titration experiments showed that amorphous AI hydroxide rapidly transformed to crystalline bayerite at the alkaline condition (pH〉10). The solution analyses after and during the titration Ksp=^aAl^3+/aH^+^3 ,was 10^10.3. The amount of consumption of added acid or base during the titration experiment was attributed to both the protonation/deprotonation of dissolved AI species and surface hydroxyl group. The surface acidity constants, surface hydroxyl density and specific surface area were estimated by FITEQL 4.0. 相似文献
82.
通过对锰氢化物、锰羰基化合物、锰羰基氢化物的形成条件和理化性质,现代火山气体化学成分,现代海底喷口热液流体成分,有关矿床矿物流体包裹体气相成分,有代表性锰矿物化学成分及铁锰结核的物质组构,菱锰矿的碳同位素组成、锰矿物的共生、伴生矿物组合的探究,认为锰氢化物、锰羰基化合物、锰羰基氢化物是原生锰矿的主要迁移形式.它们从地球深部强还原富H2、富CO高压环境通过断裂、裂隙随岩浆、热液迁移至地壳浅部,由于压力、温度骤降,氧逸度大增,H2和CO逃逸、氧化,锰氢化物、锰羰基化合物、锰羰基氢化物分解、氧化、硫化成原生锰矿,经氧化淋(浸)滤,形成锰的高价氧化矿物. 相似文献
83.
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86.
Brenda M. Miskimmin William F. Donahue Dainna Watson 《Aquatic Sciences - Research Across Boundaries》1995,57(1):20-30
Calcium hydroxide (Ca(OH)2), or hydrated lime, has recently been reintroduced in western Canada as a treatment to reduce macrophytes and algae in eutrophic waters. We examined the effects and recovery of aquatic invertebrates of the Ca(OH)2 treatment (250 mg L–1) of one half of a divided eutrophic pond compared to the untreated half. Nine weeks following treatment, total invertebrates on the untreated side were present at 1917 ± 555 individuals m–2, and on the treated side at 822 ± 186 individuals m–2. Notably, Chironomidae represented 13% of invertebrates on the untreated half, but dominated numerically with 72% on the treated half of the pond. The remaining five most abundant taxa in the untreated side were 88%–99% less abundant in the treated half of the pond. Diversity and evenness were twice as high for the untreated half as for the treated half of the pond. Because macrophytes were also extirpated with the Ca(OH)2 treatment, macrophyteassociated taxa were absent or at low numbers in the treated half. The death of organisms on the treated side of the pond may have been caused (directly or indirectly) by the pH shock associated with Ca(OH)2 treatments. Slow recolonization by most invertebrates during the year of treatment was probably due to the lack of heterogeneous macrophyte habitat. Follow-up sampling 3 years later indicated that the pond completely regained the abundance and biological diversity of flora and fauna. 相似文献
87.
A new phase of AlOOH (tentatively called δ-AlOOH) was synthesized at 21?GPa and 1000?°C and its crystal structure was identified by a powder X-ray diffraction method. Rietveld refinement revealed that this aluminum oxide hydroxide has an orthorhombic unit cell, a?=?4.7134(1) Å, b?=?4.2241(1) Å, c?=?2.83252(8) Å, V?=?56.395 (5) Å3, and Z?=?2 in the space group of P21?nm. A calculated density is 3.533?g?cm?3, which is about 4.48 and 15.04% denser than that of diaspore and boehmite, respectively. The δ-[Al0.86Mg0.07Si0.07]OOH is also stable at 21?GPa and 1000?°C, coexisting with majorite and phase egg, and its cell parameters are a?=?4.710(1) Å, b?=?4.215(1) Å, c?=?2.839(1) Å, and V?=?56.37(1) Å3. 相似文献
88.
Thermodynamic properties of high-pressure minerals that are not recoverable from synthesis experiments by conventional quenching
methods (“unquenchable” phases) usually are calculated from equation of state data and phase diagram topologies. The present
study shows that, with cryogenic methods of recovery and sample treatment, phases with a suitable decomposition rate can be
made accessible to direct thermodynamic measurements. A set of samples of Ca(OH)2-II has been synthesized in a multianvil device and subsequently recovered by cooling the high-pressure assembly with liquid
nitrogen. Upon heating from liquid nitrogen to room temperature, the material transformed back to Ca(OH)2-I. The heat effect of this backtransformation was measured by differential scanning calorimetry. A commercial differential
scanning calorimeter (Netzsch DSC 404), modified to allow sample loading at liquid nitrogen temperature was used to heat the
material from −150 to +200 °C at rates varying between 5 and 15 °C min−1. The transformation started around −50 °C very gradually, and peaked at about 0 °C. To obtain a baseline correction, each
sample was scanned under exactly the same conditions after the backtransformation was complete. Because of the relative sluggishness,
onset and offset temperatures were not well defined as compared to fast (e.g., melting) reactions. To aid in integration,
the resulting signals were successfully fitted using a generic asymmetric peak model. The enthalpy of backtransformation was
determined to be ΔH =−10.37 ± 0.50 kJ mol−1. From previous in situ X-ray diffraction experiments, the location of the direct transformation in P-T space has been constrained to 5.7 ± 0.4 GPa at 500 °C (Kunz et al. 1996). With the reaction volume known from the same study,
and assuming that ΔC
p
of the transformation remains negligible between the conditions of our measurements and 500 °C, our result gives an estimate
of the entropy of transition and the P-T slope of the reaction curve. To a first approximation, the values ΔS = −16.00 ± 0.65 J(mol · K)−1 and dP/dT = 0.0040 ± 0.0002 GPa/K have been determined. These results need to be refined by equation of state data for Ca(OH)2-II.
Received: 30 December 1999 / Accepted: 10 April 2000 相似文献
89.
不同类型氢氧化镁填充EVA复合材料性能研究 总被引:1,自引:0,他引:1
将氢氧化镁填充至EVA中,填充量分别为30%、50%,对合成的MH/EVA复合材料进行力学性能测定,比较不同水热条件对复合材料力学性能的影响;并研究了添加国产普通氢氧化镁、雅宝H-5以及通过实验制备得到的氢氧化镁对复合材料力学性能、热重分析、拉伸断面的影响。结果表明,与另外4种MH相比,160℃水热得到的MH分散性好,表面极性小,与EVA的相容性好,MH/EVA复合材料的初始分解温度高,更不易点燃,当材料承受外力时,界面层能承受较高的外力,表现出一定的韧性断裂,发生断裂时拉伸断面的拔丝现象更明显,具有较好的力学性能。因此,160℃水热合成的MH更适合做阻燃剂填充至EVA中。 相似文献
90.
研究了Fe-Al-Mg-混合金属氧化物(简称MMH)/金溪膨润土(简称MT)分散体系的触变性。实验表明,在不同的MMH/MT质量比(R)条件下,分散体系可分别呈现正触变性和负触变性。考察了pH值对纯金溪膨润土和Fe-Al-Mg-MMH/金溪膨润土分散体系触变性的影响。发现pH值能影响体系的触变性类型。当R值较小时(0~0.051),随着pH值增加,体系的触变性发生负触变性-复合触变性-正触变性的转化;而R较大的体系(0.091),在所研究的pH范围内(7.28~12.00),随着pH值增加,体系由复合触变性向负触变性转化。并对影响机理进行了初步探讨。 相似文献