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Cheang Tuckyun Zhou Hongyan Lin Weihao Zheng JiaJun Yu Liang Zhang Yongcheng 《Environmental science and pollution research international》2022,29(42):63294-63303
Environmental Science and Pollution Research - For the past few years, the environmental safety problems of radioactive nuclides caused wide public concern. In this work, the dodecyl trimethyl... 相似文献
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本文主要介绍了美国海军现用的工作服装种类、服装构成及穿着场合,并与我国海军07式作训服进行了对比分析。 相似文献
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The concept of evolvability is controversial. To some, it is simply a measure of the standing genetic variation in a population
and can be captured by the narrow-sense heritability (h2). To others, evolvability refers to the capacity to generate heritable phenotypic variation. Many scientists, including Darwin,
have argued that environmental variation can generate heritable phenotypic variation. However, their theories have been difficult
to test. Recent theory on the evolution of sex and recombination provides a much simpler framework for evaluating evolvability.
It shows that modifiers of recombination can increase in prevalence whenever low fitness individuals produce proportionately
more recombinant offspring. Because recombination can generate heritable variation, stress-induced recombination might be
a plausible mechanism of evolvability if populations exhibit a negative relationship between fitness and recombination. Here
we use the fruit fly, Drosophila melanogaster, to test for this relationship. We exposed females to mating stress, heat shock or cold shock and measured the temporary
changes that occurred in reproductive output and the rate of chromosomal recombination. We found that each stress treatment
increased the rate of recombination and that heat shock, but not mating stress or cold shock, generated a negative relationship
between reproductive output and recombination rate. The negative relationship was absent in the low-stress controls, which
suggests that fitness and recombination may only be associated under stressful conditions. Taken together, these findings
suggest that stress-induced recombination might be a mechanism of evolvability. 相似文献
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成渝城市群臭氧污染特征及影响因素分析 总被引:14,自引:0,他引:14
为研究成渝城市群O_3污染特征及其影响因素,对成渝城市群15个城市2015—2016年国控环境监测站点和国家气象台站数据进行了研究.结果表明,研究区域15个城市均存在不同程度的O_3超标现象.2015—2016年成渝城市群O_3污染形势愈发严峻,春末及夏季污染最为严重,且在7月达到O_3浓度峰值(118μg·m~(-3)),O_3污染空间分布呈片状,以资阳为中心的遂宁、眉山、成都等城市为O_3污染较为严重的区域.颗粒物、NO_2及CO均与O_3有显著相关性,其中,颗粒物与O_3浓度在冬季呈负相关,在夏季则表现为正相关.太阳辐射、气温、相对湿度及流场均是影响O_3浓度的重要因子,强辐射、高温及低湿易形成较高浓度的O_3,相对湿度对O_3浓度的影响呈先升后降的关系. 相似文献
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分析了铜和镉联合胁迫对羊角月牙藻(Selenastrum capricornutum)的影响,运用国内应用较少的新型技术——叶绿素荧光技术检测了胁迫下微藻的最大光能转化效率(Fv/Fm)受到的影响,并尝试通过膜脂过氧化损伤产物丙二醛(MDA)和其他指标在胁迫下的变化,对铜、镉联合胁迫机制进行初步探究。结果表明:(1)羊角月牙藻在铜、镉联合胁迫下生长受到抑制,表现出明显的浓度-效应关系。铜、镉的联合胁迫的相加指数为-1.63,表现为典型的拮抗作用。(2)通过叶绿素荧光技术的应用,探明Fv/Fm随毒性浓度的变化表现为浓度-效应关系,毒性浓度越大,羊角月牙藻的Fv/Fm越低,但在低毒性浓度刺激时随胁迫时间延长有回升迹象。(3)随毒性浓度的增加,羊角月牙藻的MDA增加,表现为显著的浓度-效应关系;可溶性蛋白质大体呈先升后降的趋势。(4)铜、镉联合胁迫下,MDA与羊角月牙藻生物量、Fv/Fm呈显著负相关。脂质过氧化是导致生物量下降和Fv/Fm受抑制的原因之一。(5)在微藻体内铜、镉发生拮抗作用的机制也可能与重金属的脂质过氧化作用由于拮抗受到抑制有关。 相似文献
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菖蒲对不同程度富营养化水体的净化作用研究 总被引:2,自引:0,他引:2
通过静态培养实验,研究了菖蒲(Acorus calamus L.)对5种不同程度富营养化水体水质的影响,比较了培养后各水体中菖蒲生物量变化.结果发现,TP、TN、NH4 -N、PO43- -P的去除量与水体各自初始浓度正相关.在实验初期TP、TN、NH4 -N、PO43- -P的变化速率快,后期变化速率减慢.极度富营养E组水体中营养盐去除率低于重度富营养D组水体.D组TN去除率达96.38%,TP去除率达98.32%.富营养水体D、E组COD运渐下降,中营养水体C组COD在开始水平上下轻微波动,低营养水体A、B组一周后略有上升,之后维持在7.078 mg·L-1以下.各组富营养化水体叶绿素a一周后都有明显下降,实验结束时叶绿素a下降率最高可达到98.01%,贫营养水体A组叶绿素a维持低水平.结果发现,菖蒲可以较好地净化富营养水体,同时也能保持清洁水体水质.在水体生态修复工程中具有良好的应用前景. 相似文献
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Weihao Zhang Fuqing Xu Wei He Xing Zheng Chen Yang 《Frontiers of Environmental Science & Engineering in China》2009,3(1):48-55
Based on common phenomena of biochemical interaction between plants and microorganisms, the inhibitive effects of three common
terrestrial compositae plants, namely Artemisia lavandulaefolia DC., Conyza canadensis (L.) Cronq., and Kalimeris indica (L.) Sch.-Bip. on the blue algae Microcystis aeruginosa was studied. Live compositae plants are co-cultivated with algae in two different inoculation doses for 10 days in 5-pools
incubators, in order to exclude the influence of bacteria and nutrients. The results show that Artemisia lavandulaefolia DC has the most inhibitive potential among the three plants as evidenced by the most drastic decrease in optical density
(OD680) of the algae. The inhibition rate is 93.3% (with initial inoculation dose of 2.0 × 106 Cells/mL) and 89.3% (with initial inoculation dose of 4.0 × 106 Cells/mL) respectively on the 10th day of cultivation. The average inhibition rate during the later half of the experiment is 0.76 (with initial inoculation
dose of 2.0 × 106 Cells/mL) and 0.71 (with initial inoculation dose of 4.06106 Cells/mL), respectively. Logistic model analysis shows that
compositae plants such as A. lavandulaefolia DC. causes the reduction of the habitat’s carrying capacity of algae. ANOVA analysis is used to determine the similarity
and differences between every experimental group and an average inhibitive rate model is used to evaluate the inhibition effects.
The results show that A. lavandulaefolia DC., which grow well in the aquatic environment, may have a great potential in controlling algae bloom in eutrophic water. 相似文献
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Liu Weihao Huang Haihong Liu Yun Li Lei Cheng Huanbo Liu Zhifeng 《Journal of Material Cycles and Waste Management》2021,23(4):1303-1319
Journal of Material Cycles and Waste Management - Recycling carbon fiber reinforced polymer (CFRP) waste is unavoidable for the sustainable manufacturing and cost reduction of CFRP products.... 相似文献
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为了研究孔隙水压力作用下深埋隧道掌子面的稳定性,构建了深埋盾构隧道的二维刚性有限平动多块体的破坏模式,并引入了Hoek Brown强度准则。利用极限分析得到掌子面前方土体的内部耗散能和外力做的功,利用Hoek Brown强度准则推导得到极限支护力的目标函数,通过MATLAB数值软件的规划求解得到支护力的解,和既有文献中的成果对比,2种方法得到解的最大误差为6.7%,验证了Hoek Brown强度准则的有效性。对各个岩体参数下深埋隧道掌子面极限支护力的变化规律进行分析,结果表明:深埋隧道掌子面前方的极限支护力随着扰动因子D和孔隙水压力系数ru的增大而增大,随着地质强度指标GSI和参数mi的增大而减小;破坏范围随着参数mi和孔隙水压力系数ru的增大而减小,而随着地质强度指标GSI和扰动因子D的增大而增大。研究结果可为岩质地层中深埋盾构隧道掌子面支护力的设计提供理论依据。 相似文献