雌雄比对海带雌配子体发育的影响     

罗世菊  丛沂周  杨迎霞  张全胜  李晓捷  朱龙  张壮志 《海洋湖沼通报》2005,(1):33-36

本实验进行了不同雌雄比对海带雌配子体发育的影响。结果表明：雌雄比(鲜重)为1：1及2：1，实验组出现排卵时间最早，且发育率高，实验第20天，发育率超过70％，孢子体正常。5：1，10：1，20：1实验组随着雄性比例的减少，发育率逐渐降低，随着培养天数的增加，三个实验组均出现未受精卵及畸形孢子体，雌雄比越大，未受精卵数目越多。  相似文献   

Relationship between Shot-Induced Noise and Shot Interval in Seismic Refraction Experiments at Sea     

Herber  R.  Weigel  W.  Wong  H. K. 《Marine Geophysical Researches》1997,19(3):257-265

Seismic noise induced by the seismic source during continuous profiling reduces the signal-to-noise ratio and hence the data quality. This noise is largely dependent on the shot interval. In this paper, the noise amplitude of refraction seismic records from a special experiment is analysed as a function of the shot interval. An empirical exponential relationship between mean peak noise amplitude and shot interval is deduced. By increasing the shot interval, the induced noise can be minimized on all successive records. This results in an improvement of the data, predominantly the signal-to-noise ratio. Because the seismic signal and the shot-induced noise have nearly the same spectra, the chance of improving the signal-to-noise ratio by stacking is significantly reduced.  相似文献   

Variability in maturity and growth in a heavily exploited stock: cod (Gadus morhua L.) in the Irish Sea     

Armstrong  M.J; Gerritsen  H.D; Allen  M; McCurdy  W.J; Peel  J.A.D 《ICES Journal of Marine Science》2004,61(1):98-112

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Determination of the Critical Value of Deflection for Embedded Cylindrical Structures     

刘建起陈滨  王海艳 《中国海洋工程》2005,19(3):519-528

An embedded cylinder is a large-diameter cylinder embedded in a soil foundation. The state of failure of such an embedded cylindrical structure shows large deflection instead of slide and overturn of the traditional gravity type of structure placed on a rubble base or foundation base. The critical value of deflection of the embedded cylindrical structure, which is the maximum allowable deflection for stability calculation of the cylinder, is a vital control value. Through investigation on deflection and soil pressures on an embedded cylinder by model experiments, the variations of the angle of rotation θ of a cylinder with effective anti-overturning ratio η and moment MH of thrust are discussed. On the basis of experimental study, the critical value of deflection of the cylindrical structure is proposed in the paper. Meanwhile, the formulas for calculating deflection of cylinders are derived.  相似文献   

Biogeochemical Variation in Dimethylsulfide, Phytoplankton Pigments and Heterotrophic Bacterial Production in the Subarctic North Pacific during Summer     

Kazushi Aranami  Shuichi Watanabe  Shizuo Tsunogai  Masato Hayashi  Ken Furuya  Toshi Nagata 《Journal of Oceanography》2001,57(3):315-322

Dimethylsulfide (DMS), chlorophyll a (Chl-a), accessory pigments (fucoxanthin, peridinin and 19-hexanoyloxyfucoxanthin), and bacterial production (BP) were measured in the surface layer (0–100 m) of the subarctic North Pacific, including the Bering Sea, during summer (14 July–5 September, 1997). In surface sewater, the concentrations of DMS and Chl-a varied widely from 1.3 to 13.2 nM (5.1 ± 3.0 nM, mean ± S.D., n = 48) and from 0.1 to 2.4 µg L^–1 (0.6 ± 0.6 µg L^–1, n = 24), respectively. In the subarctic North Pacific, DMS to Chl-a ratios (DMS/Chl-a) were higher on the eastern side than the western side (p < 0.0001). Below the euphotic zone, DMS/Chl-a ratios were law and the correlation between DMS and Chl-a was relatively strong (r ² = 0.700, n = 27, p < 0.0001). In the euphotic zone, DMS/Chl-a ratios were higher and the correlation between DMS and Chl-a was weak (r ² = 0.128, n = 50, p = 0.01). The wide variation in DMS/Chl-a ratios would be at least partially explained by the geographic variation in the taxonomic composition of phytoplankton, because of the negative correlation between DMS/Chl-a and fucoxanthin-to-Chl-a ratios (Fuc/Chl-a) (r ² = 0.476, n = 26, p = 0.0001). Furthermore, there was a positive correlation between DMS and BP (r ² = 0.380, n = 19, p = 0.005). This suggests that BP did not represent DMS and dimethylsulfoniopropionate (DMSP) removal by bacterial consumption but rather DMSP degradation to DMS by bacterial enzyme.  相似文献   

Seasonal variations in faunal distribution and activity across the continental slope of the goban spur area (NE Atlantic)     

Els Flach  Carlo Heip 《Journal of Sea Research》1996,36(3-4)

Density, biomass and community structure of macrofauna were estimated together with several sediment characteristics at seven stations ranging from 208 m to 4460 m water depth along the OMEX transect in the Goban Spur area (NE Atlantic) during three seasons (October 1993, May 1994, and August 1995). Median grain size decreased with increasing water depth and showed no differences between the seasons. The percentages of organic carbon and total nitrogen were highest at mid-slope depths (1000 to 1500 m), and were significantly higher in August at the upper part of the slope to a depth of 1500 m. The C:N ratio in the surface layer amounted to 7 to 8 in May, 10 to 12 in August and 14 to 17 in October at all stations (except the deepest at 4460 m, where it was 11 in May and August), indicating arrival of fresh phytodetritus in May, and therefore seasonality in food input to the benthos. Densities of macrofauna decreased exponentially with increasing water depth. Significantly higher densities of macrofauna were found in May at the upper part of the slope to a depth of 1500 m. These differences were mainly due to high numbers of postlarvae of echinoids at the shallowest station and ophiuroids at the deeper stations. Biomass values also decreased with increasing water depth, but biomass was relatively high at the 1000 m station and low at 1500 m, due to relatively high and low mean weights of the individual macrofaunal specimens. No significant differences in biomass were found between the seasons. Respiration was high (15 to 20 mgC·m⁻²·d⁻¹) in May at the upper part of the slope to a depth of 1000 m and low (1–3 mg C·m⁻²·d⁻¹) at the deeper part. At the shallowest stations to a depth of 1000 m respiration was highest in May, at the mid-slope stations (1400–2200 m) it was highest in August, whereas the deepest stations (3600 to 4500 m) did not show any differences in respiration rates. In conclusion; seasonal variation in organic input is reflected in denstiy, community structure and activity of the macrofauna along the continental slope in the NE Atlantic.  相似文献   

沉积物镁铝含量比及其古气候意义   总被引：3，自引：2，他引：3  

张士三  陈承惠 《台湾海峡》1993,12(3):266-271

沉积物的镁铝含量比——m 值(m=100×MgO/Al_2O_3)与沉积水介质的盐度、pH 水温关系密切。当水温处在冰点以下时,沉积物的m 值随水温降低而增大。当水温处在冰点以上时,水介质的盐度、pH 和水温的增加,都有利于m 值增大。由于气候条件能直接或间接地影响沉积水介质的特征,因此,沉积物的m 值对古气候的变化具有一定的判别功能。通过对中国元古宙以来沉积物m 值的分析,发现古气候的热冷变化有1200Ma 的周期,其中还有次一级的热冷气候波动。第四纪的气候是处在热气候期后期的一个冷的气候波动阶段。  相似文献   

太平洋中部表层沉积物镁铝含量比的变化   总被引：4，自引：0，他引：4  

张士三 《台湾海峡》1990,9(3):244-250

本文根据中、日调查资料,研究了太平洋中部表层沉积物镁铝含量比的变化,并探讨其影响因素。  相似文献   

Rapport ARN/ADN et evaluation de l'etat nutritionnel et de la croissance des larves de poissons marins: un essai de mise au point experimentale chez la sole (Solea solea L.)     

Bergeron  Jean-Pierre; Boulhic  Michel 《ICES Journal of Marine Science》1994,51(2):181-190

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塔里木干旱区水稻田蒸发的实验研究     

王保栋 《干旱区地理》1992,15(4):54-59

根据中科院06—02—01研究计划任务,作者于1990年开始在阿克苏水平衡站进行观测实验,获得了宝贵的第一手资料,并应用EBBR法(能量平衡——包文比法)计算了稻田的蒸发量。通过分析评价表明,由于受“绿洲效应”的影响,结果明显偏大,不符合物理规律,因此该法在干旱区绿洲的应用尚需更多的探索,有待进一步完善。  相似文献