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951.
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953.
汞胁迫对拟穴青蟹(Scylla paramamosain) 主要消化和免疫因子的影响 总被引:1,自引:0,他引:1
采用实验生态学方法,开展了汞胁迫下拟穴青蟹(Scylla paramamosain)的消化和免疫因子变动的研究。在实验室条件下,测定了0.00、0.005、0.01、0.02、0.04、0.08mg/L浓度Hg2+在1d、3d、5d、7d、9d胁迫时间下的消化和免疫因子变化。结果表明,汞胁迫下拟穴青蟹AMS活性快速升高,但激活效应随胁迫时间延长而逐渐下降,后期表现为抑制效应。汞胁迫能激发Pepsin活性,短期内Pepsin活性和胁迫浓度、胁迫时间呈正相关;长期高浓度胁迫(0.04、0.08mg/L),则激发效应减弱。汞胁迫对LPS活性的影响主要表现为抑制作用。免疫因子的研究结果表明,汞胁迫对AKP有激发作用,可迅速刺激机体AKP活力上升。低浓度汞胁迫对AKP活性提升最显著(0.005、0.01、0.02mg/L),高浓度组AKP活性先升后降。汞胁迫对ACP活性有激发作用,且存在显著的时间效应和浓度效应。汞胁迫下SOD活性短期内即显著升高,且SOD活力随胁迫时间延长而持续升高。汞胁迫对LZM活性有激活作用,且激活效应存在时间效应和浓度效应。汞胁迫对PO活力快速产生抑制作用,抑制作用存在时间效应而无显著的浓度效应。汞胁迫对拟穴青蟹消化和免疫因子能产生胁迫效应,对Pepsin、AMS、AKP、ACP、SOD、LZM表现为激发,而对LPS、PO表现为抑制。 相似文献
954.
N. Vedachalam R. Ramesh V. Bala Naga Jyothi V. Doss Prakash G. A. Ramadass 《Marine Georesources & Geotechnology》2013,31(5):525-538
ABSTRACTReliable power supply, precise position determination and effective communication are the key requirements for strategic autonomous underwater vehicles (AUV) involved in long duration scientific missions, search operations and when operated as a swarm. The paper presents the challenging range of AUV developed for deep water, Polar and intervention applications; demanding technical requirements for strategic AUV; reliability modeling done on the lithium-ion batteries to identify the redundancy requirements for achieving near-zero failures; navigation model to estimate the achievable level of position accuracies using the state-of-the-art navigation system; limitations in underwater communication; and their importance in realizing vehicle autonomy and swarm intelligence. It is identified that a strategic grade Doppler velocity- aided inertial navigation system could provide position accuracies of about 0.5% of the distance travelled when navigated using sea bottom or ice reference, and a 38?kWh lithium-ion battery pack requires about 7% redundant battery capacity to achieve a failure probability of <?1% in a period of 1 year. 相似文献
955.
通过研究不同体质量仿刺参(Apostichopus japonicus)的免疫活性, 为仿刺参生长中免疫指标的建立提供依据。实验选取了50、100、150 g 左右的仿刺参各10 只, 测定其体腔细胞数量、各细胞类群比例及部分免疫酶活性。结果表明: 不同体质量的仿刺参, 其体腔细胞数量及各细胞类群、过氧化物酶(POD)、超氧化物歧化酶(SOD)具有显著性变化, 而体腔液中酚氧化酶(PO)活性极低。体质量150 g左右仿刺参的细胞数量和SOD活性较其他两组都明显升高, 细胞类群也有明显变化(P<0.017), 但POD活性显著降低(P<0.05)。不同体质量的仿刺参免疫活性具有显著性差别, 说明了仿刺参免疫组分在生长过程中不断变化, 免疫防御能力在各阶段有所差别。 相似文献
956.
采用瓯江口实测泥沙资料,对多个典型挟沙力公式进行了系统比较;对瓯江口同步的平均流速和平均含沙量进行分析,探讨适合该河口的挟沙力关系,并引入泥沙因子,考虑泥沙粒径对水流挟沙力的影响。结果认为:各挟沙力公式的计算结果过程曲线趋势一致,只是存在量级上的差别;结合实测泥沙资料进行分析,采用河口、海岸适用性较好的水流挟沙力公式,考虑泥沙粒径对挟沙力的影响,引入泥沙因子分析拟合瓯江口水流挟沙力公式。旨在揭示不同挟沙力公式之间的联系,以及河口海域水流挟沙力拟合过程,为进一步探讨河口海岸含沙量分布和悬浮泥沙输运提供思路。 相似文献
957.
This paper describes a new framework for object detection and tracking of AUV including underwater acoustic data interpolation, underwater acoustic images segmentation and underwater objects tracking. This framework is applied to the design of vision-based method for AUV based on the forward looking sonar sensor. First, the real-time data flow (underwater acoustic images) is pre-processed to form the whole underwater acoustic image, and the relevant position information of objects is extracted and determined. An improved method of double threshold segmentation is proposed to resolve the problem that the threshold cannot be adjusted adaptively in the traditional method. Second, a representation of region information is created in light of the Gaussian particle filter. The weighted integration strategy combining the area and invariant moment is proposed to perfect the weight of particles and to enhance the tracking robustness. Results obtained on the real acoustic vision platform of AUV during sea trials are displayed and discussed. They show that the proposed method can detect and track the moving objects underwater online, and it is effective and robust. 相似文献
958.
沿海水域火/核电厂冷却水水工布置的优化原则和实践 总被引:1,自引:0,他引:1
本文结合我国沿海水域电厂冷却水工程的工程特点,着重阐明了差位式工程布置原则,从理论上分析了差位式工程布置原则与常用的布置方法的区别,该工程布置原则在台山电厂的工程实例中得到了验证。 相似文献
959.
Size-fractionated seawater samples were collected from the Gulf of Maine to determine the fraction (fc/d) of total dissolved (< 1 μm) Cd, Cu, Ni and 234Th in the colloidal size range (1,000 nominal molecular weight, NMW, to 1 μm) using cross-flow filtration. Colloidal Cd, Cu and Ni represents < 1–7% of the total dissolved concentration in these shelf waters and increases with an increase in particle concentration. By comparison, results obtained for particle-reactive 234Th indicate that < 1–47% of total dissolved is associated with the colloidal size fraction. A revised relationship between the concentration of colloids (Cc) and suspended particles (Cp) is reported (log Cc = 0.66 log Cp −2.01 kg L−1) and used to examine the dependence of fc/d for these metals on the concentration of suspended particles for Cp = 0.01–100 mg L−1. Results indicate that a significant fraction (˜ 10–30%) of Cd, Cu, Ni and 234Th in the traditionally defined ‘dissolved’ fraction may exist in the colloidal size range in regions characterized by high particle concentrations (Cp > 1–10 mg L−1), such as in near-shore and estuarine waters. 相似文献
960.
C.A.Greated 《中国海洋工程》1997,(4)
-Force measurements of oscillatory flow acting on a single circular cylinder have been carriedout.The experiments were done by oscillating a circular cylinder in still water.Instantaneous forces and ve-locity fields around the cylinder were measured by Particle Image Velocimetry(PIV).The Keulegan-Car-penter number(KC)varied in the range from 5 to 20 and the viscous parameter β=Re/KC was set at500(Re is Reynolds number).It was found that the strength and frequency of the lift force increased withKC number,the main frequency of the lift force being three times the frequency of the oscillatory flow atKC=20.The movement and strength of the vortices around the cylinder are discussed for differentKC numbers. 相似文献