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841.
Acartia bifilosa (Copepoda: Calanoida) is a common species in offing of global waters and it often becomes dominant species in some estuaries. This species develops different strategy according to variation of environment. Despite its ecological role, Acartia bifilosa also has been concerned as live feeds in aquaculture, but study on egg production rate of this species in saturated diet in different temperature and different diet is so far not available. In order to interpret the importance of temperature and diet on natural population variation and also on aquaculture as foods of larval fish, the functional response of reproductive success of Acartia bifilosa was quantified in the laboratory using different temperatures and diets. Acartia bifilosa was captured in Jiaozhou Bay and acclimated to corresponding temperature for 3~4 days. In order to reduce the effect of large extent temperature range on organism, we captured Acartia bifilosa from March to June and acclimated them to temperature which is adjacent to natural temperature. Daily egg production rate (EPR, eggs female-1day-1) was detected for 11~15 days at 5 different temperatures ranged from 8.0 to 23 °C and all the females was feed on saturated diet all through the experiments. EPR on first day was not calculated in the mean EPR to eliminate the effect of different diets. This result showed that Acartia bifilosa spawned continuously during the experiment days and no obvious regulation was found. EPR was positively correlated with temperature from 8.0 to 23 °C. The highest mean EPR was observed at 23 °C (7.3 eggs female-1day-1), and the lowest value was found at 8 °C (3.8 eggs female-1day-1). The effect of diets on EPR was evaluated at two different temperatures (8.0 °C and 12.5 °C). Same trends were found at the two temperatures: mean EPR fed on Chaetoceros sp. was higher than that fed on Skeletonema costatum, and during the 14-day experiments, EPR was higher for females fed on Skeletonema costatum than chaetoceros sp. in the first few days (3~5 days), but it changed reversely in the subsequent days until the end of the experiments. Hatched eggs were observed in the two experiments at temperature 8°C and 12.5 °C and no diapause eggs were found. The hatching success rate was low at 8°C but reached 93.2% at 12.5 °C. According to the results in this paper, we detected the comfortable temperature range for EPR, and evaluated the effect of Skeletonema costatum which often brings out red tide in natural waters. These results are beneficial to ecological research for explaining population variation and population recruitment of this species, These data also can be used in Acartia bifilosa aquaculture.  相似文献   
842.
以海洋油气开发工程为实例,利用HYSYS和PIPEFLOW软件,分析了影响海底混输管网计算的若干因素,指出了HYSYS和PIPEFLOW的适用条件,最终确立了海底混输管网优化算法,提高计算效率。  相似文献   
843.
This paper deduces the expression of the Schottky contact capacitance of AlGaN/AlN/GaN high electron mobility transistors (HEMTs), which will help to understand the electron depleting process. Some material parameters related with capacitance--voltage profiling are given in the expression. Detailed analysis of the forward-biased capacitance has been carried on. The gate capacitance of undoped AlGaN/AlN/GaN HEMT will fall under forward bias. If a rising profile is obviously observed, the donor-like impurity or trap is possibly introduced in the barrier.  相似文献   
844.
The improvement on the calculation of anti-Stokes energy transfer rate is studied in the present work. The additional proportion coefficient between Stokes and anti-Stokes light intensities of quantum Raman scattering theory as compared with the classical Raman theory is introduced to successfully describe the anti-Stokes energy transfer. The theoretical formula for the improvement on the calculation of anti-Stokes energy transfer rate is derived for the first time in this study. The correctness of introducing coefficient exp{ΔE / kT} from well-known Raman scatter theory is demonstrated also. Moreover, the experimental lifetime measurement in Er0.01YbxY1 - 0.01 - xVO4 crystal is performed to justify the validity of our important improvement in the original phonon-assisted energy transfer theory for the first time.  相似文献   
845.
通过结构为ITO/NPB(60 nm)/ Alq3 ∶1 wt% rubrene(20 nm)/ Alq3(3 nm)/ Alq3 ∶1 wt% rubrene(20 nm)/ Alq3(20 nm)/LiF/Al的双量子阱的黄色有机电致发光器件,研究了不同磁场强度下的发光效率和电流变化特性. 研究结果表明该器件的电流是随着磁场强度的增加而单调下降的,显示了器件的电阻是随着磁场强度的增加而增加的. 同时也得到了该结构有  相似文献   
846.
This paper studies the average fidelity of teleportation and thermal entanglement for a two-qubit Heisenberg XYZ chain in the presence of both an inhomogeneous magnetic field and a Dzyaloshinski--Moriya interaction. It shows that for a fixed Dz, the increase of bz will broaden the critical temperature at the cost of decreasing the thermal entanglement. And it can modulate the inhomogeneous magnetic field and the Dzyaloshinski--Moriya interaction for the average fidelity of teleportation to be optimal.  相似文献   
847.
Wave-induced seabed instability, either momentary liquefaction or shear failure, is an important topic in ocean and coastal engineering. Many factors, such as seabed properties and wave parameters, affect the seabed instability. A non-dimensional parameter is proposed in this paper to evaluate the occurrence of momentary liquefaction. This parameter includes the properties of the soil and the wave. The determination of the wave-induced liquefaction depth is also suggested based on this non-dimensional parameter. As an example, a two-dimensional seabed with finite thickness is numerically treated with the EFGM meshless method developed early for wave-induced seabed responses. Parametric study is carried out to investigate the effect of wavelength, compressibility of pore fluid, permeability and stiffness of porous media, and variable stiffness with depth on the seabed response with three criteria for liquefaction. It is found that this non-dimensional parameter is a good index for identifying the momentary liquefaction qualitatively, and the criterion of liquefaction with seepage force can be used to predict the deepest liquefaction depth.  相似文献   
848.
生物制氢研究进展   总被引:1,自引:0,他引:1  
目前, 世界上利用的能源90%以上都是“化石能源”(如石油、煤炭和天然气等)。随着人类不断利用这些不可再生的“化石能源”, 它将会逐渐枯竭, 且其燃烧形成的产物(如CO2和SO2等)造成的严重环境污染(如温室效应和酸雨), 也有害于人类健康。因此, 人类正面临着能源紧缺和环境污染的双重压力。为满足能源需求量日益增长和环境保护的需要, 我们必须寻找环保型的可再生能源来替代“化石能源” 以满足人类对能源的需求。 在各种可再生能源中氢能将有可能替代“化石能源”,成为未来能源利用的主要形式。氢能具有许多优点:①氢能燃烧时只生成水, 不产生任何污染物, 甚至连CO2也不会产生, 实现真正的“零污染” 和“零排放”;②氢能的能量密度高, 放热高达122 kJ/g, 是焦炭放热的4.5倍, 汽油的2.68倍;③氢能可经济有效的输送和储存, 可以利用已有的天然气管道输送, 输送成本低, 甚至优于输电, 因为输送氢能不会产生如电能输送过程中所产生的能量损耗;氢能的存储也比较简便, 其中储氢合金材料就是一种非常理想的储氢方法, 该方法储氢能力强、运输方便、操作容易, 且安全可靠。在利用储氢合金进行储氢时, 还可用以进行制冷或采暖(Kulkova et al., 2006), 因为储氢材料在吸氢时放热, 在放氢时吸热。正因为氢能具有如此多的优点, 许多大的跨国公司开始对制氢技术高度关注, 如主要汽车制造商(通用、福特、戴姆勒-克莱斯勒等)对开发以氢能作为燃料的汽车投入大量的人力和物力;宝马公司从20世纪70年代就开始研制以氢能为能源的汽车, 宝马公司现在已拥有了时速达240km的氢能汽车(Munro,2003)。同时, 一些发达国家的科研院所的科学家们对氢能的制备方法、制氢机制以及提高产氢量等进行了大量的研究。  相似文献   
849.
INTRODUCTIONIntheseaareaofNanshaIslands,therearemanyshoalpatchandrapids.Themajorareaisclassifiedas"dangerouszone".Thereforeitisverydifficulttomakeanormalinvestigationonit.Consideringtheremotesensinginformationfeaturesreflectedbythecontrolfunctionoflocalgeographicstructureandthegrowthofcoralisletsandreefs,wefindthatthemostimportantfeatureofthegeographicsystemofNanshaIslandsisthatitsdistributionisregional.Thetrendsurfaceanalysissystembasedontheremotesensingcompositeinformationistoemulatet…  相似文献   
850.
INTRODUCTIONTheattentiontothestudyofmetalsinthemarineaerosolparticulatesisincreasingduetotheirenvironmentalecologicaleffectsandcontributiontothebiogeochemicalcycle.Intheaspectofenvironmentalecologicaleffects,first,onthesideofclimate,aerosolswithmetalscanactascloudcondensationoricenuclei,absorbandscattersolarradiation,andaffecttheradiationbudgetontheearth.Therelativelyhighironcontent(5%)ofthedustcanabsorbtheshortwavelengthradiationefficiently.Second,onthesideofecologicaleffects,di~lvedAlse…  相似文献   
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