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281.
Environmental Science and Pollution Research - Resource endowment and economic development of different provinces in China vary greatly, resulting in large amount of CO2 transfers. We need further...  相似文献   
282.
对栉孔扇贝Chlamysfarreri 的卵原细胞和卵母细胞发育过程的超微结构和细胞化学研究结果表明:卵原细胞的胞质中含大量的游离核糖体,细胞器不发达,蛋白质和RNA丰富而糖元贫乏;卵黄生成之前,卵母细胞中的核质膨大为生发泡;核仁发达,胞质中线粒体大为增多;卵黄体和皮层颗粒首先出现于核周,接近线粒体聚集处;卵黄生成盛期,卵母细胞的胞质内具平行片层粗面内质网和同心圆状粗面内质网,它们是生成卵黄体和皮层颗粒的主要细胞器,线粒体和高尔基器也参与了这两种内含物的生成;微胞饮作用也为细胞的发育提供某些物质;卵黄体含蛋白质和糖元,皮层颗粒富含多糖类;卵黄膜形成始于卵黄生成初期,先是细胞游离端的胞质出现一个富含多糖的突起,突起部的质膜微绒毛化,微绒毛分泌产生由中性多糖构成的卵黄膜,继而向四周扩展,并于卵母细胞成熟时覆盖整个细胞;RNA 合成贯穿于卵母细胞的整个发育期,延续至卵黄生成结束之后,成熟分裂临近之时.  相似文献   
283.
养殖海湾扇贝弧菌病的研究   总被引:11,自引:0,他引:11  
当大连近海的海湾扇贝(Argopecten irradians)养殖群体发生流行病时,从患病扇贝的血淋巴中分离出一个优势菌株,作纯培养;经肌肉注射感染,健康扇贝个体表现出与原发病相同症状,证明该菌株是病原菌,经形态、生理、生化测定,鉴定该种细菌为哈氏弧菌(Vibrio harveyi)。不同温度下注射不同密度细菌的感染试验证明,哈氏弧菌的致病性与感染强度及温度有密切关系,海区细菌数和弧菌数监测结果表明,扇贝养殖区的细菌数和弧菌数高于养殖区外,8~9月的细菌数和弧菌数高于其余月份。图3表4参20。  相似文献   
284.
生物表面活性剂对铜绿假单胞菌摄取烷烃的强化机制   总被引:3,自引:1,他引:3  
考察了2株铜绿假单胞菌(Pseudomonasaeruginosa)以正十六烷为底物生长的不同方式,并初步探讨了生物表面活性剂在烃类降解菌摄取烷烃过程中的作用机制.菌株O-2-2在正十六烷中的生长明显快于PS-1,生长过程中O-2-2分泌出鼠李糖脂生物表面活性剂,正十六烷被完全乳化.另外,O-2-2菌细胞表面疏水性高于PS-1,而加入鼠李糖脂使得菌体细胞中脂多糖含量减少,菌细胞表面疏水性明显提高.上述结果表明,鼠李糖脂主要通过乳化疏水性底物和提高降解菌表面疏水性两种机制强化铜绿假单胞菌(P.aeruginosa)对烷烃的摄取.图6表1参14  相似文献   
285.
Emissions from industrial activities pose a serious threat to human health and impose the need for monitoring both inorganic and organic pollutants in industrial areas.We selected Masson pine (Pinus massoniana L.) as potential biomonitor and collected the current (C) and previous year (C+1) needles from three industrial sites dominated by petrochemical,ceramics manufacturing,and iron and steel smelting plants and one remote site to determine heavy metals (Cu,Cd,Pb,Zn,Cr,Ni and Co) and polycyclic aromatic hydrocarbons (PAHs) in unwashed and water-washed needles.Both unwashed and washed C+1 needles showed generally higher concentrations of heavy metals and PAHs than C needles,although the washed needles more clearly spotlighted the accumulation effect of PAHs over exposure time.Water-washing resulted in a significant decrease in needle PAH concentrations with more significant effects shown in C needles.By contrast,needle heavy metal concentrations were much less affected by washing.Although heavy metals and PAHs might differ in adsorption and uptake strategies,their higher concentrations in the needles at the industrial sites indicated conspicuous contamination due to industrial emissions there,The PAH distribution patterns in pine needles accorded with the real types of energy consumption in the study sites and were efficiently used for pinpointing local pollutant sources.  相似文献   
286.

Technological innovation is one of the potential engines to mitigate environmental pollution. However, the implementation of new technologies sometimes fails owing to socioeconomic constraints from different stakeholders. Thus, it is essential to analyze constraints of environmental technologies in order to build a pathway for their implementation. In this study, taking three technologies on rural sewage treatment in Hangzhou, China as a case study, i.e., wastewater treatment plant (WTP), constructed wetland (CW), and biogas system, we analyzed how socioeconomic constraints affect the technological choices. Results showed that socioeconomic constraints play a key role through changing the relative opportunity cost of inputs from government as compared to that of residents to deliver the public good—sewage treatment—under different economic levels. Economic level determines the technological choice, and the preferred sewage treatment technologies change from biogas system to CW and further to WTP along with the increase of economic level. Mismatch of technological choice and economic level results in failures of rural sewage treatment, e.g., the CW only work well in moderately developed regions in Hangzhou. This finding expands the environmental Kuznets law by introducing the coproduction theory into analysis (i.e., inputs from both government and residents are essential for the delivery of public goods and services such as good environmental quality). A match between technology and socioeconomic conditions is essential to the environmental governance.

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287.
288.
黄河口水动力作用的最显著特点是径流方向(WE)和潮流方向(SN)近于垂直。这一特点有利于三角洲的横向扩展[1],但另一方面,由于沿岸流异常发育,加快了河口沉积速度,促进了拦门沙的发育,使河口处的河床抬高,泄流不畅,不利于黄河口外水下河道的自然下切延伸,最终诱发改道。米草生态工程可以通过防止泥沙沿岸搬运,降低海水含沙量,从而降低拦门沙的发育速度,保护黄河水下河道,最终起到降低河口变动频率,防治黄河改道的作用。  相似文献   
289.
Distributed photovoltaic (PV) generation is a promising pathway for reducing carbon emission and meeting energy demands in electricity sector. Subsidies are essential to accelerate its deployment. This paper aims to study the optimal subsidy levels for distributed PV generation from the perspective of maximizing the net policy benefits (environmental and economic) by applying the principal–agent theory, which is a commonly used method of analyzing government incentive issues. Based on a detailed analysis of asymmetric information and of benefit conflicts between the government (the principal) and the investor (the agent), the optimal subsidy principal–agent model is established, in which the investor’s preference toward distributed PV generation is asymmetric and is described by a random variable. The equivalent model is then presented to obtain the optimal solutions, and a numerical example is provided to test the effectiveness of the model and to illustrate the implications of the solutions. The results show that high net policy benefits are directly influenced by a high investor preference. This emphasizes the importance for the government of improving the investor’s preference level and of eliminating asymmetric information to develop distributed PV generation and reduce subsidy costs. Additionally, lowering the market risk and enlarging the overflow value of distributed PV generation both contribute to subsidy cost savings. This paper offers policy makers an effective subsidy scheme to accelerate distributed PV generation development and will also be a useful reference for government to subsidize other renewable power systems to mitigate global climate and energy changes.  相似文献   
290.
电梯门区故障是电梯整体主要故障之一。基于目前电梯门区常见故障或者已经发生的事故,本文系统性地建立电梯门区故障案例库并进行其软件研发;根据故障案例库中已知的案例信息得到故障类型风险的相关信息,进行风险分析;将故障案例中实际出现的故障类型组合种类归纳后,计算出每种组合的危害程度,按照危害程度值进行降序排列;软件系统根据用户输入的设备信息给出风险较高的故障组合和相应的预防措施。  相似文献   
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