广西合浦海草床生态系统服务功能价值评估

海草床生态系统是生物多样性丰富和生产力高的近岸海洋生态系统,本文以广西合浦海草床为例,结合实地调查、已有的研究成果和当地统计资料,综合运用生态经济学、资源经济学等基本理论和方法,对该地区海草生态系统的服务功能进行了价值评估。结果表明2005年该地区海草生态系统的服务功能价值为6．29×105元／a·ha,其中间接利用价值最大,为4．47×105元／a·ha,占总经济价值的70．97％;其次为非利用价值,为1．54x105元／a·ha,占总经济价值的24．52％;最少的是直接利用价值为2．84×104元／a·ha,仅占总经济价值的4．51％。     

圆柱型土元对高脂血症小鼠脂肪代谢的影响

土元是我国传统医学中常用的原料,圆柱型土元是苏土元在养殖过程中发现的变异品种.本研究分析了圆柱型土元的一般营养成分,并用圆柱型土元对高脂血症模型小鼠进行降血脂活性评价.Balb/c雄性小鼠分别喂食标准饲料、1%胆固醇饲料和含10%圆柱型土元粉末的1%胆固醇饲料3周,分析了圆柱型土元对小鼠空腹血脂和肝脏脂肪浓度的影响.结果显示,圆柱型土元可降低高血脂小鼠血液中总胆固醇(P<0.05)、甘油三酯浓度(P<0.001)、低密度脂蛋白胆固醇浓度(P<0.05),提高血液高密度脂蛋白胆固醇水平(P<0.05)、降低动脉硬化指数(P<0.001).同时,圆柱型土元可降低高血脂小鼠肝脏甘油三酯浓度(P<0.001).本研究结果提示,圆柱型土元可能会对由高血脂引发的动脉粥样硬化和高脂肪饮食造成的脂肪肝具有一定的预防和治疗作用.     

冬季北黄海表层海水pCO_2分布及其影响因素探讨

根据2006年12月在北黄海走航连续观测所得pCO2 数据,结合水文、化学和生物等要素的同步观测资料,对该海域pCO2分布及其影响因素进行了探讨.结果表明:冬季北黄海表层海水pCO2测值在203～683 μatm之间,平均值为408 μatm.辽南沿岸流及其影响区域是大气CO2汇区;山东半岛以北沿岸,122°E以西受渤海环流输送,黄河悬浮颗粒物影响的高浑浊度区域是大气CO2的一个强源区(最高值达到683 μatm);而占据北黄海大部的黄海混合水以及北黄海整体上是大气CO2的弱源.冬季北黄海表层海水pCO2分布主要受控于海水温度、碳酸盐体系平衡和生物活动,即温度越高pCO2越高、DIC 越高pCO2越高、叶绿素含量越高pCO2越低.其中辽南沿岸流及其影响区域生物活动的影响最为显著.而山东半岛以北沿岸的高浑浊度区域水体性质具有特殊性,较高的 pCO2受控于高的DIC浓度以及陆岸的影响.     

硬盘数据恢复技术在数字化测绘生产中的应用

目前数字化测绘生产中大量数据主要依赖于硬盘存储,由于各种原因导致硬盘数据丢失时有发生。介绍了硬盘数据恢复的基本原理与方法,该方法能有效地恢复硬盘丢失的数据,确保数字化测绘生产数据的安全。     

广东沿海牡蛎体Ni含量水平及其时空变化趋势

198 9～ 1997年间 ,为实施“南海贻贝观察”计划 ,对广东沿海 12个地点近江牡蛎体内的 Ni含量水平进行了连续监测 ,结果全部牡蛎样品均检出 Ni,含量范围为 0 .17～ 2 .37mg/kg(湿重 ) ,总平均值为0 .58mg/kg。污染评价结果显示 ,广东沿海 Ni含量总体上处于微污染—轻污染水平。牡蛎体 Ni平均含量呈珠江口海区 >粤西海区 >粤东海区的分布格局 ,其最高值出现在深圳湾、唐家湾和湛江港。 70年代后期至 1991年 ,牡蛎体的 Ni含量呈明显下降趋势 ,此后 Ni含量年际间虽有波动 ,但无显著差异     

基于空间杜宾模型的中国高学历人才时空分异研究

基于2001~2016年全国统计年鉴数据,采用集聚度分析和空间自相关分析等方法,描绘中国高学历人才的空间格局及变化,并采用空间杜宾模型,探究影响高学历人才空间分布的主要因素及空间溢出效应。结果表明：（1）中国人才分布表现出较大的非均衡性,集聚程度表现为东南高、西北低,且2000~2015年间,人才稀疏区面积下降而集聚区面积上升;（2）中国人才密度的全局莫兰指数为正,表明中国的高学历人才分布具有一定的空间集聚特征,而2000~2015年此指数有所下降,表明人才分布整体上有分散趋势。2000年热点区与次级热点区主要分布于京津冀和长三角地区,其中热点区为京、津、沪;而2015年,热点以及冷点区域均有所扩张,表明局部地区人才仍然有集中化的趋势;（3）工资水平、高校发展、公共服务水平是决定人才空间分布的主要因素,但没有证据表明生活支出比、失业率、房价有显著影响。人才分布具有明显的空间溢出效应,同时工资水平、高校发展、公共服务水平等影响因素也具有明显的空间溢出效应。     

Characterization of Turbot(Scophthalmus maximus) Skin and the Extracted Acid-Soluble Collagen

The biochemical composition of the turbot skin was investigated. The moisture level of the skin was found to be 51.4%. Based on dry matter content, there were relatively high protein(82.1%) and lipid(13.1%) concentrations in the turbot skin. Mineral element analysis revealed that the turbot skin had high Ca content(2069.0 mg kg^-1), and the concentrations of toxic heavy metals Hg and Pb were less than 0.005 mg kg^-1, which indicates that the turbot skin is a safe resource for collagen production. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE) analysis showed that acid-soluble collagen(ASC) extracted from the turbot skin was type-I collagen. The imino acid content of the ASC was 241.6 per 1000 amino acids, which suggests a relatively high denaturation temperature. The Fourier transform infrared(FTIR) spectra of ASC reflected a highly stable structure, and the measured denaturation temperature of ASC was 29.5℃, which is higher than those from many temperate fishes. ASC was the most soluble at pH 4.0, and when the pH values were below or above 4.0, the solubility decreased rapidly. The ASC exhibited a relatively high solubility when NaCl concentration was lower than 2%. These results show that turbo skin can be employed as a source for producing collagen with high quality.     

Base cation concentrations in forest litter and topsoil have different responses to climate and tree species along elevational gradients

The forest litter is an essential reservoir of nutrients in forests, supplying a large part of absorbable base cations(BC) to topsoil, and facilitating plant growth within litter-soil system. To characterize elevational patterns of base cation concentrations in the forest litter and topsoil, and explore the effects of climate and tree species, we measured microclimate and collected the forest litter and topsoil(0-10 cm) samples across an elevational range of more than 2000 m(1243 ～ 3316 m a.s.l.),and analyzed the concentrations of BC in laboratory. Results showed that: 1) litter Ca concentration displayed a hump-shaped pattern along the elevational gradients, but litter K and Mg showed saddle-shaped patterns. Soil Ca concentration increased with elevation, while soil K and Mg had no significant changes. 2) Ca concentration in the forest litter under aspen(Populus davidiana) was significantly higher than that in all other species, but in topsoil, Ca concentration was higher under coniferous larch and fir(Larix chinensis and Abies fargesii). Litter K and Mg concentrations was higher under coniferous larch and fir, whereas there were nosignificant differences among tree species in the concentrations of K and Mg in topsoil. 3) Climatic factors including mean annual temperature(MAT), growing season precipitation(GSP) and non-growing season precipitation(NGSP) determined BC concentrations in the forest litter and topsoil. Soil C/N and C/P also influenced BC cycling between litter and soil. Observation along elevations within different tree species implies that above-ground tree species can redistribute below-ground cations, and this process is profoundly impacted by climate. Litter and soil Ca, K and Mg with different responses to environmental variables depend on their soluble capacity and mobile ability.     

铣削斜楔形区域形成及其对流场负压区的影响规律

【目的】研究在内喷淋冷却高速铣孔加工中,铣削斜楔形区域的形成对流场负压区的影响。【方法】对高速湿式铣削加工区域建立三维流场模型,应用计算流体力学软件Fluent,采用非结构化四面体网格单元,利用滑移网格技术对高速铣削过程进行三维瞬态计算。【结果】得到不同刃数、不同转速的立铣刀对同一孔径工件进行切削时流场的压力分布情况。三刃立铣刀斜楔形对流场负压影响最大,当立铣刀刃数增加时,此斜楔形区缩小,负压减小,转速为10 000～20 000 r/min时增长速度逐渐降低,20 000～35 000 r/min时增长速度逐渐增高。【结论】从流场角度分析,流场中最大负压值与转速呈正相关,转速的提高增加了抑制空化的难度;增加铣刀刃数,可减小流场斜楔形区面积,减小空化可能。