围压对冻结粉土动力特性的影响   总被引：1，自引：4，他引：1  

沈忠言  张家懿 《冰川冻土》1997,19(3):245-251

通过恒应速率控制下等应变幅三轴动强度，对不同围压下的冻结粉土的应力－应变关系，动强度、破坏时间和破坏振次以及退荷回弹动弹模的讨论，认为围压效应有增强效应（提高动强度）和减强效应（降低动强度）两部分合成。在低围压时，围压效应中增强效应占主导、动强度随围压增加而提高；围压达到一定值之后，减强效应起主导作用，动强度随围压增加而下降，导致这一特点的主要机理是，围压作用下冰点下降引起冻土的未冻水含量增大和基  相似文献   

Accumulation of copper in the Permian Kupferschiefer: A result of post-depositional redox reactions     

W. Püttmann  H. Heppenheimer  R. Diedel   《Organic Geochemistry》1990,16(4-6)

Within the Central European Zechstein Basin the Permian Kupferschiefer has been deposited under anoxic conditions. In most parts of the basin, the metal content does not exceed values commonly observed in black shales. However, in areas near to the Zechstein sea-shore which are simultaneously related to rift zones a significant base metal enrichment is observed. Organic geochemical analyses of the copper-mineralized sections in the Kupferschiefer from Southwest Poland show that significant changes in the composition of organic matter are associated with the metal enrichment processes. Porphyrins, commonly abundant constituents of the shale, have been decomposed by oxidizing fluids. Additionally, aliphatic hydrocarbons have been largely removed from the bitumen and alkylated aromatic systems were affected by side-chain degradation. This particular type of alteration is explained by ascending oxidizing solutions which transported high amounts of base metals from Lower Permian red beds into the Kupferschiefer horizon acting as a geochemical trap. The metal precipitation is suggested to be a result of thermochemical sulphide production with organic matter acting as hydrogen source. In areas such as the Lower Rhine Basin in the bottom section of the Kupferschiefer the base metals lead and zinc as well as barium have been accumulated from basinal Carboniferous formation waters. Copper enrichment is not observed because potential source rocks are missing in this area. However, the observed compositional changes of the organic matter do not point towards thermochemical redox processes.  相似文献   

藻酸双酯钠对蛋白激酶A活性的影响     

肖殿模  张亚海  王小鲁  张俊宝  杨国栋  陈华粹 《中国海洋大学学报(自然科学版)》1992,(Z1)

大鼠肝脏经匀浆、硫酸铵盐析和DEAE-纤维素柱层析,得到部分纯化的Ⅰ型和Ⅱ型蛋白激酶A。将两型酶制剂在体外分别与藻酸双酯钠孵育,藻酸双酯钠对两型酶的活性均有剂量依赖性抑制作用。  相似文献   

硫酸铵对钝顶螺旋藻（spirulina platensis）生长的影响   总被引：2，自引：0，他引：2  

张成武  唐乐同 《海洋湖沼通报》1992,(2):35-39

本实验利用硫酸铵代替zarrouk培养基中的硝酸钠。在硫酸铵的最适用量范围内钝顶螺旋藻spirulina platensis生长良好。不同用量的硫酸铵,对钝顶螺旋藻的生长,以及叶绿素和脱镁叶绿素含量有明显影响。钝顶螺旋藻生长,最佳时硫酸铵用量为0.1g/l,粗蛋白含量为51.35％。  相似文献   

The relationship between seagrass (Posidonia oceanica) decline and sulfide porewater concentration in carbonate sediments   总被引：2，自引：0，他引：2  

Maria Ll. Calleja  Núria Marb  Carlos M. Duarte 《Estuarine, Coastal and Shelf Science》2007,73(3-4):583-588

In this study we test the hypothesized negative relationship between seagrass status and porewater hydrogen sulfide (H₂S) levels, through a comparative analysis within a range of seven Posidonia oceanica meadows growing over carbonate sediments in the NW Mediterranean Sea around Mallorca Island. The studied meadows range from meadows growing on sediments with very low sulfide porewater concentrations (4.6 μM) to those growing over higher sulfide conditions (33.5 μM). Organic matter content, sulfate reduction rates and sulfide porewater concentrations in the sediments were determined concurrently with the assessment of demographic plant dynamics (specific mortality and net population growth rates). Sulfide porewater concentration increased with increasing organic matter content in the sediment, while net population growth decreased significantly with low increases of sulfide concentrations. Our results confirm the previously suspected vulnerability of seagrass meadows growing on carbonate sediments to increased sulfide levels. An excess of 10 μmols H₂S L⁻¹ porewater is identified to already conduce P. oceanica meadows to decline, which this study identifies, particularly, as strongly sensitive to sulfides. The results reported here suggest that even moderate increases in organic carbon inputs may lead to enhancement of dissolved sulfides and may be an important factor for seagrass status in these iron-depleted carbonate sediments from the Mediterranean Sea.  相似文献   

藻酸双酯钠粘度的影响因素     

万忠良 《中国海洋大学学报(自然科学版)》1992,(Z1)

通过实验讨论影响藻酸双酯钠特性粘度[η]升降的几个因素。  相似文献   

The Robinson Forest environmental monitoring network: Long-term evaluation of streamflow and precipitation quantity and stream-water and bulk deposition chemistry in eastern Kentucky watersheds     

Kenton L. Sena  Tanja N. Williamson  Christopher D. Barton 《水文研究》2021,35(4):e14133

  相似文献   

Effect of widespread severely acidic soils on spatial features and abundance of trace elements in streams   总被引：1，自引：0，他引：1  

Mats strm 《Journal of Geochemical Exploration》2001,73(3)

In the coastal area of western Finland, a large number of streams are strongly acidic and contaminated with metals. The reason for this is not historical and present industrial, mining and urban activities, but a current high rate of weathering and leaching of widespread acid sulphate soils (pH 2.5–4.0) developed in artificially drained Holocene marine and lacustrine sulphide-bearing sediments. Evaluation of existing hydro- and geochemical field and experimental data revealed that: (1) cobalt, Ni and Zn are extensively leached from the acid sulphate soils and thus exist abundantly in streams affected by such soils, (2) copper and Tl are also leached abundantly from the acid sulphate soils, although not to the same extent as are Co, Ni and Zn, (3) vanadium is in general depleted and Cr only weakly enriched in streams draining ‘the average acid sulphate soil’, but they increase substantially in severely acidic streams in catchments underlain with particularly acidic soil, (4) arsenic and Pb are not leached more abundantly from the acid sulphate soils than from the common types of soils and sediments (till, glaciofluvial deposits, peat) resulting in aquatic abundance and distribution patterns unrelated to the acid sulphate soil occurrences.  相似文献   

新型硫木质素复合浆液的研制及其性质研究          下载免费PDF全文

阮文军 《地质与勘探》2001,37(3):75-77

在原硫木质素浆液的基础上，通过加入适量的无机物（D）可以得到一种新型硫木质素复合浆液，与以前的硫木质素液相比，硫木质素复合浆液强度更高，价格更低廉，浆液胶凝时间更易调控，这种性能优良的新型复合浆液在工程中将有良好的应用前景。  相似文献   

利用工业废镍催化剂制结晶硫酸镍的研究     

廖戎  万积秋 《矿物岩石》1995,15(3):87-89

本文扼要介绍利用工业废镍催化剂制结晶硫酸镍的实验研究。实验结果表明，其产品质量达到国家标准，回收率达８８％。  相似文献