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141.
两种海洋微藻硝酸还原酶活性测定方法的比较研究   总被引:1,自引:0,他引:1  
对6种常见海洋微藻的硝酸还原酶活性测定方法进行了初步研究。确立了离体法和活体法的提取(振荡)时间及酶促反应时间,分别为:5 min,30 min(离体法)和6 min,10 min(活体法),并对2种方法进行了对比。结果表明:在本文条件下,离体法较活体法更适于进行塔玛亚历山大藻(Alexandrium tamarense)、强壮前沟藻(Amphidinium carterae)、中肋骨条藻(Skeletonema costatum)、新月菱形藻(Nitzchia closterium)和旋链角毛藻(Chaetoceros curvisetus)的硝酸还原酶活性的测定;活体法更适于东海原甲藻(Prorocentrum donghainase)硝酸还原酶活性的测定。  相似文献   
142.
143.
长江口区风浪要素计算的探讨   总被引:2,自引:0,他引:2  
本文以长江口区波浪实测资料为依据,对目前国内外常用的风浪要素计算方法进行了比较分析,认为就目前资料条件下,最适用于长江口区的、能满足工程设计等要求的风浪要素计算方法为莆田试验站方法(莆田公式)。  相似文献   
144.
本文将分形作为一个新概念,应用到海洋化学的液-固界面作用的一系列的研究上。根据用SAXS法测定一些常见的粘土矿物(高岭石,蒙脱石)和水合氧化物(水锰矿、δ-MnO_2、氧化铁凝胶、针铁矿、无定形氧化铁)的分维结果,可将这些结果划分成三类:(1)小尺度模量下具有表面分形;大尺度模量下具有质量分形。(2)只有一种分维值的表面分形。(3)在小尺度模量下和大尺度模量下分别具有不同分维值的表面分形。  相似文献   
145.
V. Prabhakar  J. Pandurangan   《Ocean Engineering》2006,33(8-9):1044-1055
A polar method for obtaining wave resonating quadruplets {K1, K2, K3, K4} in the computation of nonlinear wave–wave interaction source term of the wave model is presented with results for both deep and finite water depths. The method first determines the end radial points of the locus equation for K2, for each set of input wave vectors (K1, K3) on the symmetry. The locus of K2 (and hence K4) is then traced in the anti-clockwise direction starting with the maximum radial point on the line of symmetry. It is shown that when k3>k1, the number of points on the locus varies when the orientations of the input wave vectors are changed and reduces when the difference in the magnitude of the input wave vectors is increased. A significant advantage in this method is that the angular increment on the locus for K2 can be kept constant.  相似文献   
146.
The numerical investigation of random wave slamming on superstructures of marine structures in the splash zone is presented in this paper. The impact pressures on the underside of the structure are computed based on the improved volume of fluid method (VOF). The governing equations are Reynolds time-averaged equations and the two equation k model. The third order upwind difference scheme is applied to the convection term to reduce the effect of numerical viscosity. The numerical wave flume with random wave-maker suitable for VOF is established. Appropriate moving contact-line boundary conditions are introduced to the model wave in contact with and separated from the underside of structure. Parametric studies have been carried out for different incident waves, structure dimensions and structure clearance. The numerical results are verified by the experimental results.  相似文献   
147.
Thirteen vertical profiles of 226Ra and 222Rn in the near-surface water were obtained in the western North Pacific in winter, and the gas transfer velocities across the air-sea interface were estimated. The transfer velocities found by applying a steady state model varied widely from 2.1 to 30.2 m day−1 with a mean of 9.4 m day−1. The mean value is almost 5 times higher than that in summer in other oceans, and the maximum value is a record high for world oceans. This is partly due to the inadequacy of the steady state model, which overestimates when stronger winds blow in more recent days than the 222Rn half-life of about 4 days. In fact, a strong low pressure zone passed through the station about 2 days earlier, which was one of the low pressure zones that with a period of develop once a week or so in the northwestern North Pacific in winter. Instead of steady-state removal, if half of the radon removal occurred sporadically every 7 days, and the last removal took place two days before the observation, the transfer velocity would be 26 m day−1. Our mean transfer velocity, which is less than 20% different from the steady state value including both overestimated and underestimated values, 9.4 ± 4.8 m day−1, seems to represent the mean state of this region in winter. This suggests that the gas exchange fluxes under extremely rough conditions in the open ocean are larger than those estimated by using a transfer velocity equation with a linear or quadratic relationship with wind speed. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
148.
鱼类生长激素的异源表达、应用及安全性评价   总被引:3,自引:0,他引:3  
鱼类生长激素对鱼的生长发育起着重要的调节作用,能促进鱼体快速生长,提高饵料转化率,在水产养殖业中具有重大应用价值。转生长激素基因鱼具有快速生长效应,可以缩短养殖周期,降低养殖成本和风险。鱼类生长激素基因异源表达体系的建立和发展,使获得大量廉价的鱼类生长激素产品成为可能,为鱼类养殖业新型饵料添加剂的研制开辟了新的途径。本文综述了转生长激素基因鱼和鱼类生长激素基因的异源表达两方面的研究及其安全性评价。  相似文献   
149.
A new method is presented to process and correct full-depth current velocity data obtained from a lowered acoustic Doppler current profiler (LADCP). The analysis shows that, except near the surface, the echo intensity of a reflected sound pulse is closely correlated with the magnitude of the difference in vertical shear of velocity between downcast and upcast, indicating an error in velocity shear. The present method features the use of echo intensity for the correction of velocity shear. The correction values are determined as to fit LADCP velocity to shipboard ADCP (SADCP) and LADCP bottom-tracked velocities. The method is as follows. Initially, a profile of velocity relative to the sea surface is obtained by integrating vertical shears of velocity after low-quality data are rejected. Second, the relative velocity is fitted to the velocity at 100–800 dbar measured by SADCP to obtain an “absolute” velocity profile. Third, the velocity shear is corrected using the relationship between the errors in velocity shears and echo intensity, in order to adjust the velocity at sea bottom to the bottom-tracked velocity measured by LADCP. Finally, the velocity profile is obtained from the SADCP-fitted velocity at depths less than 800 dbar and the corrected velocity shear at depths greater than 800 dbar. This method is valid for a full-depth LADCP cast throughout which the echo intensity is relatively high (greater than 75 dB in the present analysis). Although the processed velocity may include errors of 1–2 cm s−1, this method produced qualitatively good current structures in the Northeast Pacific Basin that were consistent with the deep current structures inferred from silicate distribution, and the averaged velocities were significantly different from those calculated by the Visbeck (2002) method.  相似文献   
150.
Mesoscale features in the eastward extension of the Kuroshio were investigated using assimilation of TOPEX/POSEIDON (T/P) data into a three-layer quasi-geostrophic model. The T/P data exhibited an elongated state of the southern recirculation gyre in 1993–95 and 1997, between whose two periods the gyre had a contracted state in 1995–96. A few stationary eddies were located in the southern gyre during the contracted state. The baroclinic instability, which was indicated by the phase shift from the uppermost-to the lowest-layer anomalies toward the downstream side, was evident near the Kuroshio Extension (KE) path. Since the instability never appeared in the artificial model without bottom topography, the topographic barrier for the eastward flow in the lowest layer was a necessary condition for the instability. The instability synchronized with the transition in the western region of the KE axis from the elongated to the contracted states. This evolution was interpreted as if the baroclinic instability played some part in the KE states and was a trigger for the transition from the elongated to the contracted states.  相似文献   
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