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1.
Though developed as a solution for the waste problem, biodegradable plastics create new challenges on waste management with respect to policies and laws, waste management technologies and application of market-based instruments. A holistic view and integrated approach are necessary to address the implication of each component of this picture on others and on the whole. In an effort to tackle the challenges, the paper makes an in-depth analysis of the waste management system with biodegradable plastics as an element, emphasizing on regulatory and economic aspects.  相似文献   

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Secondary copulatory structures are well-known in male dragonflies and spiders. Here I report a secondary copulatory organ in female ground weta, Hemiandrus pallitarsis (Ensifera, Orthoptera - crickets and allies). The organ, located on the underside of the abdomen, appears to secure the male's genitalia during the transfer of a spermatophylax nuptial meal to this location, an area quite separate from the female's primary copulatory structures, where the sperm ampulla is attached.  相似文献   

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Many animals use body coloration as a strategy to communicate with conspecifics, prey, and predators. Color is a trade-off for some species, since they should be visible to conspecifics but cryptic to predators and prey. Some flower-dwelling predators, such as crab spiders, are capable of choosing the color of flowers where they ambush flower visitors and pollinators. In order to avoid being captured, visitors evaluate flowers visually before landing. The crab spider Mecaphesa dubia is a polymorphic species (white/purple color morphs), which inhabits the flower heads of a dune plant, Palafoxia lindenii. Using full-spectrum photography of spiders and flowers, we evaluated how honeybees perceived the spiders at different distances. Using visual modeling, we obtained the chromatic and achromatic contrasts of the spiders on flower heads as perceived by honeybees. Purple morphs were found mainly on the receptacle area and white morphs were equally likely to be found in the flowers and receptacle. According to theoretical modeling, white morphs were visible to honeybees from a distance of 10 cm in receptacle area but appeared to be cryptic in the flower area. Purple morphs were cryptic on the receptacle and less so when they were on the flowers. Spiders on flower heads are predicted to be more easily detected by honeybees using chromatic contrast. Our study shows that the conspicuousness of flower dwelling spiders to honeybees depends on the color morph, the distance of observation, and the position of spider on the flower head.  相似文献   

5.
A clean technology in thermal power station by adding of limestone into coal for getting the co-melted compounds was studied. Comparing with conventional technology, the quantity of ash discharged is decreased from 85% to 15%, the water consumption is 80% less than traditional method. The slag discharged could be used as raw materials for cement and bricks. In addition, the SO2 content is decreased as well.  相似文献   

6.
实验室叶绿素a浓度测定   总被引:2,自引:0,他引:2  
浮游植物是海洋和湖泊的一级食物链,是原生产力的指标,而浮游植物是由水体中的一种色素通过太阳光光合作用引起生化反应的结果,这种在海洋和湖泊中的色素称为叶绿素a,所以,海洋学家和湖沼学家通常以叶绿素a的浓度来评价原生产力。所以,弄清沿海及湖泊的叶绿素a浓度的时空分布及变化规律,对于生态研究有重要意义。目前,科学家采用各种手段调查叶绿素a浓度的分布,如早期的船走样采水样实验室测定,发展到船走航式测试,目前,已发展到应用航空和航天遥感技术测量等。但诸类测量中都离不开实验室一定量水样的叶绿素a浓度来作为标定其它类型资料,以建立它们之间的相关关系式。我们对杭州西湖水和东海沿岸31个站位水样中的叶绿素a进行了测量、分析、发现测量的一致性、精度等都十分理想。  相似文献   

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During the last century, approximately 30 hypotheses have been constructed to explain the evolution of the human upright posture and locomotion. The most important and recent ones are discussed here. Meanwhile, it has been established that all main hypotheses published until the last decade of the past century are outdated, at least with respect to some of their main ideas: Firstly, they were focused on only one cause for the evolution of bipedality, whereas the evolutionary process was much more complex. Secondly, they were all placed into a savannah scenario. During the 1990s, the fossil record allowed the reconstruction of emerging bipedalism more precisely in a forested habitat (e.g., as reported by Clarke and Tobias (Science 269:521–524, 1995) and WoldeGabriel et al. (Nature 412:175–178, 2001)). Moreover, the fossil remains revealed increasing evidence that this part of human evolution took place in a more humid environment than previously assumed. The Amphibian Generalist Theory, presented first in the year 2000, suggests that bipedalism began in a wooded habitat. The forests were not far from a shore, where our early ancestor, along with its arboreal habits, walked and waded in shallow water finding rich food with little investment. In contrast to all other theories, wading behaviour not only triggers an upright posture, but also forces the individual to maintain this position and to walk bipedally. So far, this is the only scenario suitable to overcome the considerable anatomical and functional threshold from quadrupedalism to bipedalism. This is consistent with paleoanthropological findings and with functional anatomy as well as with energetic calculations, and not least, with evolutionary psychology. The new synthesis presented here is able to harmonise many of the hitherto competing theories.  相似文献   

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太湖叶绿素a浓度预测模型初探   总被引:2,自引:0,他引:2  
以太湖2005年的监测资料为基础,运用多元统计回归和BP人工神经网络方法构建模型,探求叶绿素a与水深、水温、营养盐等10项环境因子之间的关系,通过验证发现BP模型对叶绿素a浓度的拟合值与叶绿素a浓度的实测值之间的均方误差为220.3059,优于统计回归模型的235.4569;此外对两种模型进行了灵敏度测试,结果都显示总磷不是太湖叶绿素a浓度的限制因子,而水深、水温、总氮的变化对叶绿素a浓度影响显著。本研究对太湖叶绿素a浓度预测模型的建立是十分有意义的。  相似文献   

9.
Soil samples were collected from three plots under di erent land utilization patterns including degradation, farming, and restoration. The abundances of methanotrophs were quantified using real-time polymerase chain reaction (PCR) based on the pmoA and 16S rRNA genes, and the community fingerprint was analyzed using denaturing gradient gel electrophoresis (DGGE) aiming at pmoA gene. Significantly lower 16S rRNA and pmoA genes copies were found in the degradation treatment than in farming and restoration. Higher abundances of Type I than those of Type II methanotrophs were detected in all treatments. The treatment of farming was clearly separated from degradation and restoration according to the DGGE profile by cluster analysis. The lowest diversity indices were observed in the F (farming plot), suggesting that the community structure was strongly a ected by farming activities. There were significantly positive correlations between the copy numbers of pmoA also Type II-related 16S rRNA genes and soil available K content. Strong negative and positive correlations were found between Type I and soil pH, and available P content, respectively. We concluded that the vegetation cover or not, soil characteristics including pH and nutrients of P and K as a result of anthropogenic disturbance may be key factors a ecting methanotrophic communities in upland soil.  相似文献   

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本文分析了环境监测中建立回归方程的程序和必须的条件,同时着重分析了回归方程y=bx+a中截距产生的原因和性质,以及利用回归方程计算痕量待测物或空白浓度出现负值时如何处理,提出见解。这对于环境监测分析人员日常分析测试中正确进行实验、正确计算、深刻理解常用的回归方程有一定的指导作用。  相似文献   

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A small subwatershed of Chaohu Lake was chosen for research on the relationships of landuse,nonpoint source pollution and its prevention.The distributions of nitrogen and phosphorus in the different land use types were shown by monitoring N and P in water samples from rainfall,surface runoff,ponds,a stream and the lake,and in soil samples from rice fields,nonirrigated land and mountain forests.A multi-pond agroecosystem was found to prevent the nonpoint source pollutants and sediment loading to eutrophic Chaohu Lake from its catchment area,because this multi-pond system can effectively keep water and nutrients inside the catchment area and be reused to irrigate the rice field.It requires only a Small investment and energy consumption.and that is suitable for this large under-development agricultural watershed.  相似文献   

12.
IntroductionThedyeingwastewaterofwoolenmillcontainsalotkindsofpollutants,suchasacidicdyes,dispersedyes,mordantdyes,auxiliaries,saltsandsoon .Theeffluentsfromwastewatertreatmentplantsfortreatmentofthedyeingwastewaterofwoolenmillswithnormalbiologicalproce…  相似文献   

13.
黄河流域近40a积温动态变化研究   总被引:8,自引:0,他引:8  
论文应用国家气象局提供的黄河流域109个气象站点40a的气象资料和中国数字高程模型,采用 “回归分析计算+残差插值”法对黄河流域≥0℃和≥10℃的积温进行栅格化,得到10a尺度的栅格面,在ArcGIS中分别对≥0℃和≥10℃的积温栅格面进行空间分析和统计分析。结果表明:40a间≥0℃积温保持不变的面积占84.59%,积温段ⅰ(<2 000℃)升到积温段ⅱ(2 000~3 000℃)的为2.07%,积温段ⅱ升到ⅲ(3 000~4 000℃)的为3.14%,积温段ⅲ升到ⅳ(4 000~5 000℃)的为3.35%,积温段ⅳ升到ⅴ(>5 000℃)的为3.76%;40a间≥10℃积温保持不变面积占85.58%,积温段ⅱ升到ⅲ的为7.31%,积温段ⅰ升到ⅱ、积温段ⅲ升到ⅳ和积温段ⅳ升到ⅴ占的面积较小,分布不集中。总体来说黄河流域≥0℃、≥10℃年积温值呈升高的趋势,主要是受全球气候变暖的影响。  相似文献   

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环境污染对人体健康的危害已为世人所关注,二恶英事件的发生使得人类对有机化合物的污染更趋重视,在众多有机化学污染物中,苯并(a)芘的毒性不但可与二恶英并驾齐驱,甚至有过之而无不及,世界卫生组织国际癌症研究中心经大量的动物试验以及临床观察分析,指定其为一级致癌物质,本文将与大家一起探讨,揭示其本质。  相似文献   

17.
李斌 《黑龙江环境通报》2002,26(1):82-82,70
通过一元线性回归的论述,提出了截距a与误差的去除。  相似文献   

18.
IntroductionInrecentyearsxenobioticshavecaughtworldsattentionbecausetheyarepoorlybiodegradableandthreatenpublichealthifhandle...  相似文献   

19.
In an effort to protect the quality of the water system, interest in non-point source pollution is increasing. Recently, studies of non-point sources pollution are continuing in relation to various land- use areas, but such studies have not been fully conducted in railway facility sites. Using monitoring data of railway bridge area with concrete road-bed, the runoff characteristics, pollutant unit loads, and first flush criteria were assessed. Railway bridge area with concrete road-bed typically show the first flush effect, and the pollutant unit load was determined to be higher than other public facilities areas. Further, the first flush criteria show an effective rainfall amount of 7 mm. In other words, from the runoff of railway facilities, considerable amounts of non-point source pollutants are occurred, indicating the need to create best management practices which are adequate for railway facility sites.  相似文献   

20.
The prevalence and genetical diversity of human Sapovirus were studied during an 18-month study in Ría do Burgo, an estuary nearby the city of A Coruña in Galicia (NW Spain). Sapovirus was detected using RT-qPCR procedure in 30 out of 80 mussel samples (37.5 %). Quantifications ranged from 2.2 × 103 to 2.1 × 105 RNA copies per gram of digestive tissue. Detection occurred mainly during the cold and rainy seasons of the period studied. Sequences obtained could be distributed into 5 genotypes being the most abundant GI.1 and GI.3. Results obtained indicate that the hydrodynamic characteristics of the harvesting area and the proximity of population density clearly influence the presence of the virus in shellfish.  相似文献   

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