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111.
112.
O. V. Kopelevich S. V. Sheberstov O. Yunev O. Basturk Z. Z. Finenko S. Nikonov V. I. Vedernikov 《Journal of Marine Systems》2002,36(3-4)
Absolute values of chlorophyll a concentration and its spatial and seasonal variations in the Black Sea were assessed by using satellite CZCS and in situ data. Since the satellite CZCS had operated for the 1978–1986 period, CZCS data was used for assessing the past state of the Black Sea just before the onset of drastic changes observed in late 1980s. The approach used for the calculation of the absolute values of chlorophyll a concentration from CZCS data was based on the direct comparison of in situ chlorophyll a data and those of CZCS and by applying the algorithm developed for the transformation of CZCS data into chlorophyll a values. CZCS Level 2 data related with pigment concentration having a spatial resolution of 1 km at nadir were used. The daily Level 3 files were derived by binning Level 2 values into 4-km grid cells and the monthly and seasonal Level 3 files were created by averaging the daily Level 3 files over the corresponding period. In situ chlorophyll a data were obtained by spectrophotometric and fluorometric methods in 15 scientific cruises over the 1978–1986 period. Total number of ship-measured data used for the comparison with those CZCS values was 590.Chlorophyll a concentration (Chl) was derived from CZCS values (C) with regression equations Chl=kC; the coefficient of transformation k was calculated from six different data sets by taking into account distinctions between subregions and seasons. The reasons for difference in the k values have been analyzed.Statistical comparison of the chlorophyll a values measured in situ and those derived from CZCS data was based on log-transformed data and gave the following results: regression SLOPE=0.842, regression INTERCEPT=−0.081, coefficient of determination (R2)=0.806, root–mean–square ERROR=0.195. The mean monthly chlorophyll a distributions derived from CZCS data over 1978–1986 have been constructed and the mean seasonal chlorophyll a values in different regions have been calculated and analyzed. The significant difference in chlorophyll concentration between the western shelf regions and the open part of the Black Sea has been demonstrated, especially in warm season. At almost all seasons, the highest chlorophyll concentration is observed in the western interior shelf region which is under strong influence of Danube. The summer mean chlorophyll concentration in this region is 18 times higher than that in the open parts and about nine times higher than in the eastern shelf region. The greatest seasonal variations are observed in the open part of the Black Sea: chlorophyll concentration in cold season is four to six times higher than in summer and three to five times higher than in April and October. To the contrary, in the western interior shelf regions, the concentration is higher in May–October (about twice than that in November–March). Seasonal variations in the western outer shelf regions are smoothed out as compared with both the western interior shelf and the open regions. 相似文献
113.
A study of the response of chlorophyll-a biomass to a winter upwelling event off Western Iberia using SeaWiFS and in situ data 总被引:2,自引:0,他引:2
Observations of a winter upwelling event off Western Iberia shelf/slope in the area of influence of the Western Iberia Buoyant Plume (WIBP) were conducted in February 2000. Spatial patterns and time evolution of the chlorophyll-a (chl-a) biomass are analysed, based on in situ and satellite data. SeaWiFS-derived chl-a concentration L2 products were used to track the chlorophyll front and estimate its westward migration velocity (maximum up to 29 km day−1), as well as to characterize the frontal system and its evolution. A method associating the type of spectral signature of a pixel to the fraction of chlorophyll probed by SeaWiFS enabled the estimation of the chl-a biomass within error intervals. High chlorophyll concentrations (for wintertime) were observed over the shelf and slope, up to large distances to the coast. Due to the WIBP, a shallow Ekman layer developed, being nearly coincident with the stratified upper meters. The transport comprised westward advection and stretching of the plume, with little entrainment with the offshore deep mixed layer waters. The relative enlargement of the total area of the Inside-Front Zone (IFZ) during the upwelling event was roughly accompanied by the maintenance of the average biomass per unit of area, considering the water column up to depths of interest. This suggests that there was a net increase of chl-a biomass inside the water column associated with the IFZ, roughly proportional to the increase in the IFZ area. Retention of phytoplankton in the shallow stratified nutrient-rich waters of the WIBP was a key factor for this increase in chl-a biomass. 相似文献
114.
EFFECTOFCO-SUPPLEMENTATIONOFVITAMINEANDSELENIUMONNORMALANDMALIGNANTCELLPROLIFERATIONHuWenliang;LiuLihua;AnthonyTDiplock.(Depa... 相似文献
115.
TB880E型掘进机应用研究 总被引:1,自引:0,他引:1
刘孟山 《铁路工程造价管理》2007,22(3):4-7
由铁道部出资7.3亿元购置的2台TB880E型掘进机,先后完成了秦岭特长Ⅰ线隧道、磨沟岭隧道、桃花铺1号隧道的掘进任务,累计掘进长度22162m。这2台掘进机自2002年工程完工后,维修、保养、存放至今。TB880E型掘进机的正常使用寿命应在8000台班左右,可以完成35~40km隧道的掘进任务。此文结合秦岭特长隧道、乌鞘岭特长隧道施工方案,对掘进机与钻爆法的优缺点进行对比分析,探讨TBM剩余寿命期的利用问题,以期为今后选择合理的隧道建设方案提供参考。 相似文献
116.
高隆昌 《西南交通大学学报》1988,(2)
本文对一个n维Lotka-Volterra型捕食系统(1)用几何、代数及分析的方法给出了一般讨论,得到了系统(1)的一些性质和全局渐近稳定的一些充分条件。最后,作为例子,把这些结果用于n=4的情形,并作了适当的生态学解释。 相似文献
117.
维生素E对糖尿病大鼠高级糖基化终末产物及其受体和肾功的影响 总被引:2,自引:0,他引:2
目的观察维生素E对糖尿病大鼠高级糖基化终末产物(AGEs)及其受体(RAGE)和肾功能的影响。方法利用链脲佐菌素腹腔注射法诱导建立糖尿病大鼠模型。将实验用SD大鼠随机分为正常对照组(NC组)、糖尿病组(DM组)和维生素E治疗组(VE组),治疗8周。观察大鼠的一般状况,监测血糖(BGL)、糖化血红蛋白(HbA1C)、尿素氮(BUN)、血肌酐(Scr)、内生肌酐清除率(Ccr)、尿白蛋白排泄率(UAER)、肾重/体重比值;应用荧光显微镜观察肾脏组织AGEs,免疫组化方法检测RAGE含量。结果①与NC组比较,DM组大鼠体重、血糖、HbA1C、BUN、UAER、肾重/体重比值均明显增高(P<0.01),Ccr明显下降(P<0.01),肾脏AGEs及RAGE含量均明显增高(P<0.01);②与DM组相比,VE组UAER、肾重/体重比值明显降低(P<0.05),Ccr明显升高(P<0.01),肾脏AGEs及RAGE含量均明显降低(P<0.05)。结论维生素E无降糖作用,但可能通过减轻糖尿病大鼠肾组织的非酶糖基化过程,从而减轻AGEs与受体结合后导致的对肾脏组织的损伤,对糖尿病大鼠肾脏具有保护作用。 相似文献
118.
Seasonal SeaWiFS chlorophyll a concentrations cycles and annual changes of altimeter Sea Level Anomaly are derived for the subtropical North Atlantic near 35°N and along a Gulf Stream axis. Spatial structure of SeaWiFS, is defined in terms of deviations from a local seasonal cycle and examined in relation to altimeter eddy structure. In the subtropical region near 35°N, SeaWiFS structure is evident during the spring bloom period with a scale of 430 km, or about twice the eddy scale. A Gulf Stream axis has been selected as a region where the Sea Level Anomaly variance is a maximum. Eddy propagation speeds and scales are examined. Cold-core (cyclonic) rings correspond to areas of high SeaWiFS chlorophyll a. Warm-core (anticyclonic) rings relate to areas of low chlorophyll concentration. Both SeaWiFS structure and eddy structure have a spatial scale of 450 km or twice the ring scale along the Gulf Stream axis. SeaWiFS chlorophyll anomalies and Altimeter Sea Level Anomaly structure have an overall negative correlation coefficient of r = − 0.34. Swirl currents between eddies redistribute surface chlorophyll concentrations and can spatially bias maximum and minimum concentration levels off eddy centre. 相似文献
119.
从电子商务中商品信息及其评价获取的实际应用出发,在分析了搜索技术在电子商务中的作用和应用现状的基础上,设计了一个用于搜索商品信息和商品评价的Internet信息搜索系统;并从实现技术上,提出了开发这个系统的体系结构,分析了各组成模块的功能和特点,着重研究了Internet信息搜索系统中的网络蜘蛛相关技术。 相似文献
120.
随着世界经济的发展,世界海运货物周转量随之增加,国际海运业的碳排放量持续增长,航运业减排的任务十分艰巨。本文结合航运业碳排放的特点,研究分析了国际海事组织(IMO)、欧盟及航运企业采取的一系列减排措施和采取的行动,为我国航运业减少碳排放提供了借鉴和参考依据。 相似文献