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671.
A sensitivity scale for criteria used in cytogenetic monitoring was constructed on the basis of published data and the results
of experiments on exposingZebrina pendula Schirt. plants to radon at various equivalent volume equilibrium activities. It was found that nucleolar activity and suppression
of mitotic activity are the most and the least sensitive parameters in terms of response to stress, respectively. 相似文献
672.
Indriķis Krams 《Behavioral ecology and sociobiology》2000,48(2):147-153
The risk of predation may influence the acquisition of energy and the feeding activity of animals. Feeding activity and body
reserves of wintering great tits Parus major in response to the priority to food access were studied in two areas differing in incidence of predators. The one-predator
area contained sparrowhawks Accipiter nisus only, whereas the two-predator area contained both sparrowhawks and pygmy owls Glaucidium passerinum, whose hunting periods overlap at dawn and dusk. In the two-predator area dominant great tits arrived at feeders significantly
later in the morning, and left earlier in the evening, than their subordinate flock-mates. Hence, feeding day length of dominants
was found to be significantly shorter. The reverse was true for the one-predator area. In addition, dominants carried significantly
greater reserves than subordinates in the area inhabited by two predators. Factors constraining subcutaneous energy reserves
were also studied in removal experiments. After the removal of dominant individuals, subordinate great tits did not reduce
their body reserves in the two predator area. In contrast, subordinate great tits significantly reduced evening body reserves
in the single-predator area. I concluded that the presence of the two predators increases unpredictability in feeding conditions
for great tits. Dominant individuals responded to this by shortening their feeding day and increasing body reserves at dusk.
Received: 8 December 1999 / Received in revised form: 15 March 2000 / Accepted: 31 March 2000 相似文献
673.
Start-up performances of dry anaerobic mesophilic and thermophilic digestions of organic solid wastes 总被引:6,自引:0,他引:6
Two dry anaerobic digestions of organic solid wastes were conducted for 6 weeks in a lab-scale batch experiment for investigating the start-up performances under mesophilic and thermophilic conditions. The enzymatic activities, i.e., β-glucosidase, N-α-benzoyl-Largininamide (BAA)-hydrolysing protease, urease and phosphatase activities were analysed. The BAA-hydrolysing protease activity during the first 2-3 weeks was low with low pH, but was enhanced later with the pH increase. β-Glucosidase activity showed the lowest values in weeks 1-2, and recovered with the increase of BAA-hydrolysing protease activity. Acetic acid dominated most of the total VFAs in thermophilic digestion, while propionate and butyrate dominated in mesophilic digestion. Thermophilic digestion was confirmed more feasible for achieving better performance against misbalance, especially during the start-up period in a dry anaerobic digestion process. 相似文献
674.
WANG Jian-li ZHONG Jun-bo GONG Mao-chu LIU Zhi-min ZHAO Ming CHEN Yao-qiang 《环境科学学报(英文版)》2007,19(6):644-646
Five monolithic catalysts with low noble metal content were prepared by irnmerge method (Pt/γ=Al2O3, Pt/La-Al2O3, Pt/YSZ-AI203, Pt+Pd/La-Al2O3 and Pd/La-Al2O3) and their activity measurements were carried out in a conventional fixed-bed flow reactor. The results show that La-Al2O3 can promote activity of the prepared catalysts and can decrease the complete conversion temperature of cooking fume. The Pt/La-Al2O3 catalyst has the highest activity and can be applied in wide range of gas hourly space velocity (GHSV). Some characterizations (XRD, TPR) were carried out with the objective to explain differences in catalytic behaviors. The prepared catalyst showed a great potential for application. 相似文献
675.
LIU Ting-feng SUN Cheng TA N HONG Jun YANG Shao-gui CHEN Chuan-xiang 《环境科学学报(英文版)》2007,19(10):1235-1238
The influence of coexisting copper (Cu) ion on the degradation of pesticides pyrethroid cypermethrin and cyhalothrin in soil and photodegradation in water system were studied.Serial concentrations of the pesticides with the addition of copper ion were spiked in the soil and incubated for a regular period of time,the analysis of the extracts from the soil was carried out using gas chromatography (GC).The photodegradation of pyrethroids in water system was conducted under UV irradiation.The effect of Cu~(2 ) on the pesticides degradation was measured with half life (t_(0.5)) of degradation.It was found that a negative correlation between the degradation of the pyrethroid pesticides in soil and Cu addition was observed.But Cu~(2 ) could accelerate photodegradation of the pyrethroids in water.The t_(0.5) for cyhalothrin extended from 6.7 to 6.8 d while for cypermethrin extended from 8.1 to 10.9 d with the presence of copper ion in soil.As for photodegradation,t_(0.5) for cyhalothrin reduced from 173.3 to 115.5 rain and for cypermethrin from 115.5 to 99.0 min.The results suggested that copper influenced the degradation of the pesticides in soil by affecting the activity of microorganisms.However, it had catalyst tendency for photodegradation in water system.The difference for the degradation efficiency of pyrethroid isomers in soil was also observed.Copper could obviously accelerate the degradation of some special isomers. 相似文献
676.
677.
研究了保存温度以及添加稳定剂、氧化剂、还原剂、螯合剂和金属离子对集胞藻(Synechocystis sp. PCC6803)野生型菌株产生的溶血素的溶血活性的影响.结果表明,该溶血素在提取初始仅具有较低的溶血活性,但在提取3~6 d后,溶血活性急剧升高,之后随保存时间延长逐渐降低.-20 ℃低温保存有利于该溶血素活性的维持.添加半胱氨酸盐酸盐、牛血清白蛋白和血红蛋白都能提高其溶血活性,可以作为该溶血素的稳定剂;氧化剂H2O2能显著提高其溶血活性,而还原剂β-巯基乙醇、二硫苏糖醇显著抑制其溶血活性,说明该溶血素为非巯基依赖型溶血素.金属离子Ca2+,Co2+,Fe3+,Ni2+,Cu2+,Mn2+和Mg2+均会抑制其溶血活性,仅Zn2+能增加其溶血活性,金属螯合剂EDTA也能增强其溶血活性. 相似文献
678.
不同共代谢基质对白腐菌降解吲哚的作用研究 总被引:1,自引:0,他引:1
选用氨氮、苯酚和喹啉作为吲哚的共代谢基质,通过白腐菌BP对共基质体系的降解研究了白腐菌在秸秆滤出液培养基中对不同共基质体系的代谢过程,并进行了动力学分析,考察了不同共代谢基质物质对白腐菌漆酶分泌和吲哚降解的影响.结果显示,不同降解体系中的白腐菌都可去除99%以上的吲哚.充分的氮源可提高白腐菌的活性和漆酶酶活的峰值;共基质苯酚和喹啉可以增加白腐菌漆酶产量,为吲哚的降解提供较多的电子,同时苯酚和喹啉也能得到较高的去除.在秸秆滤出液中,白腐菌在pH为6~8之间对吲哚都具有较强的降解能力.吲哚在白腐菌的代谢过程中,可能首先在吡啶环的2和3位发生一步羰基化. 相似文献
679.
可持续发展理念下的地质环境承载力初步探讨 总被引:4,自引:1,他引:3
在环境承载力概念的基础上定义了地质环境承载力,讨论了地质环境承载力的内在涵义及特点,以城市地质环境为例,探讨了地质环境承载力评价的工作程序。 相似文献
680.