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51.
长牡蛎碱性磷酸酶的分离纯化及部分性质研究 总被引:5,自引:1,他引:5
本文以长牡蛎为酶源提取材料,用正丁醇抽提,硫酸铵分级分离,DEAE-52和Sephadex G-100柱层析,得到一定纯度的碱性磷酸酶,提纯倍数为61.96,比活力达1.326U/mg.该酶的最适pH值9.6,最适温度38℃,初速度6.8μmol/(dm~3·min),米氏常数Km值为1.30mmol/dm~3.实验结果表明,Mg~(2+)对该酶有明显的激活作用;Zn~(2+)、Cu~(2+)、Hg~(2+)对该酶有明显的抑制作用. 相似文献
52.
赤点石斑鱼人工配合饵料中蛋白质最适含量的研究 总被引:11,自引:1,他引:11
本文探讨了不同蛋白质含量的配合饵料对赤点石斑鱼(Epinephelusakaara)生长的影响。通过60d度验得出:在各配合饵料组中,蛋白质含量为49.52%的试验的相对增重率(46.84%)体长相对增长率(15.96%)、蛋白质效率(60.35%)和饵料转化率(29.85%)等均为最佳。配合饵料组鱼体肌肉营养成分(蛋白质、脂肪、氨基酸和鲜味氨基酸)也均优于对照组,而更接近野生鱼。经回归方程分析,赤点石斑鱼人工配合饵料中蛋白质最适含量为48.37%~49.24%。 相似文献
53.
Ho Il Yoon Myung Woo Han Byong-Kwon Park Jae-Kyung Oh Soon-Keun Chang 《Marine Geology》1997,140(3-4):265-282
High-resolution (3.5 kHz and multi-channel) seismic profiles and piston cores were collected from Maxwell Bay and its tributary embayment, Marian Cove, in the South Shetland Islands, Antarctica, during the Korea Antarctic Research Program (1992/93 and 1995/96) to elucidate the glaciomarine sedimentation processes and recent glacial history of the area. Seismic data from Maxwell Bay reveal a rugged bay margin and flattened basin floor covered with well-stratified hemipelagic muds. On the base-of-slope, acoustically transparent debris flows occur, indicating downslope resedimentation of glaciomarine sediments. Despite the subpolar and ice-proximal settings of Marian Cove, the seafloor is highly rugged with a thin sediment drape, suggesting that much of the area has been recently eroded by glaciers. Sediment cores from the cove penetrated three distinct fining-upward lithofacies: (1) basal till in the lower part of the core, accumulated just seaward of the grounding line of the tidewater glacier; (2) interlaminated sand and mud in the middle part, deposited in ice-proximal zone by a combination of episodic subglacial meltwater inflow and iceberg dumping; and (3) pebbly mud in the upper part, deposited in ice-distal zone by both surface meltwater plume and ice-rafting from the glacier front. A reconstruction of the glacial history of these areas since the late glacial maximum shows an ice sheet filling Maxwell Bay in late Wisconsin time and grounding of the tidewater glacier in Marian Cove until about 1300 yr BP. 相似文献
54.
虾肤诱食剂改善南美白对虾植物蛋白日粮的作用 总被引:6,自引:0,他引:6
用900尾平均体质量为0.106 g/尾±0.012 g/尾的南美白对虾(Peneausvannamei)进行虾肽改善植物蛋白日粮试验,结果表明:(1)大豆粕、杂粕组南美白对虾的成活率显著高于鱼粉组(P<0.05);(2)大豆粕、鱼粉组南美白对虾相对生长率、饲料系数、虾体组成相似,杂粕组最差,且与大豆粕、鱼粉组有显著性差异(P<0.05)。结果表明,在南美白对虾日粮中虾肽作为营养性诱食剂可显著改善植物蛋白的适口性,提高南美白对虾对大豆蛋白的的消化吸收功能,达到与鱼粉组相同的养殖效果,从而明显降低南美白对虾日粮成本。 相似文献
55.
富含半胱氨酸肠蛋白是一种含双锌指结构的小分子蛋白,其在锌离子转运、个体发育、免疫防御以及肿瘤发生等多种生理过程中发挥重要作用。作者主要对富含半胱氨酸肠蛋白的结构特点及其在发育和免疫方面的研究进展进行系统概述,并指出其相关作用机制尚待深入研究。 相似文献
56.
57.
To study the time-varying influence of the Congo River and the Benguela Current on the deposition at the Angola Continental Margin, a high-resolution reflection seismic survey was carried out on the northern Congo Fan. Four seismostratigraphic units have been defined for the upper 800 m (1000 ms TWT) of the data. The units record different depositional environments, ranging from pre-establishment of the Congo River drainage system to the influence of the Benguela Current. An indication of a general change in the turbidite system is provided by a shift in channel distribution and a relocation of the depocentre of coarse material. The ascent of salt is recorded up to the Pliocene. Gas that has migrated out of Lower Cretaceous shales and that was produced from large quantities of organic matter in the younger sediments can be found on the flanks and on top of the salt domes. In a few places, this gas even ascends to the ocean floor along structural pathways through the topmost unit. 相似文献
58.
Nowadays there are some chronic serious environmental problems, such as eutrophication, blue tide and so on, in a complicated coastal zone or a semi-enclosed bay, because the water exchanges between an inner bay and an outer sea is weak compared with the supply of contaminant. Under this situation, a method to improve the water quality by 3-dimensional small unsymmetrical structures has been proposed by Komatsu et al. In this paper, several numerical simulations of the tidal current and concentration for various arrangements of bottom roughness in a semi-enclosed model bay are carfled out with a depth-averaged 2-D numerical model. The model is solved by the hybrid finite analytic method with nonstaggered grid. And the SIMPLES algorithm with Rhie and Chow' s momentum interpolation technique is used for the simulation. The effect of Komatsu' s method for water purification is examined by numerical simulation. The result of numerical experiment indicates that it is possible to generate a new tidal residual current and to activate a tidal exchange by bottom roughness arrangement only. 相似文献
59.
三角褐指藻(Phaeodactylum tricornutum)和翦股颖草属禾草(A-grostis capillaris)经过处理后再用液相层析法从中提取一种金属结合多肽,极谱分析表明不同的镉结合多肽具有不同的稳定性,金属结合与金属硫蛋白不同,在电位--1.7V附近未出现氧催化峰,金属硫蛋白以及从单胞藻和禾草中提取的多肽在极谱测定过程中都在电位-520mV和-930mV附近出现双峰,在-520mV处,半波电位显示了单个镉硫醇键的还原,在-930mV处的峰是由于镉和硫多齿螯合的还原,因此这通常可用以鉴定镉螯合物。在镉浓度为5umol/dm^3和10umol/dm^3时-930mV的峰高与镉浓度之间存在着对应关系。 相似文献
60.
Guanting Reservoir (GR) is one of the most important water sources for Beijing and neighboring regions. Due to water pollution, it was withdrawn from the system to supply Beijing drinking water; however, after a thorough treatment process, GR was made a reserve water source since 2007. To develop a comprehensive and quantitative analysis of water yield and purification services in the GR watershed, this study selected two time periods: the period when GR was withdrawn from the system supplying local drinking water and the period that it has been designated a reserve water source. The InVEST model was used to evaluate the quantities of water yields, and total nitrogen and total phosphorus outputs from 1995 to 2010 Additionally, the spatiotemporal variations of water yield services and water quality purification services in the GR watershed were analyzed. The results showed that water yield services in the GR watershed first weakened and then became stronger, but weakened overall during the years 1995 to 2010. Water yield capacity in the basin decreased from 1.89×109 m3 in 1995 to 1.43×109 m3 in 2010 (a drop of 24.0% in total). Water quality purification services also showed the same tendency. Total nitrogen output decreased from 4028.7 t in 1995 to 3611.4 t in 2010, while total phosphorus decreased from 379.7 t in 1995 to 354.0 t in 2010. Nitrogen and phosphorus purification services were enhanced by 10.4% and 6.8%, respectively. Changes in the climate and land use were the main factors which lead to the changes in the water yield service in the GR watershed. Policies intended to protect water resource have matched the varying trends of water quality purification services during different periods. On one hand, the research results provide a foundation to identify key fields for eco-compensation in the Guanting Reservoir basin. On another hand, the ecosystem service value will increase on the basis of eco-compensation criteria through setting the scenarios of returning farmland to forest and ecological protection. This method directly reflects increases in ecosystem service values that have occurred since measures to protect the ecological environment have been implemented. This method is more persuasive and feasible than using eco-compensation criteria based on regional ecosystem service values determined by land use/ coverage type. It can provide a new way to assess eco-compensation in the Guanting Reservoir basin and other regions. 相似文献