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861.
饮用水中卤乙酸和三卤甲烷的形成及影响因素研究 总被引:12,自引:0,他引:12
以浙江省钱塘江流域的七种水源水为代表,分析了前体物、pH值、投氯量、氯化时间和温度等因素对氯化消毒副产物(DBPs)中三种卤乙酸(HAAs)和三种三卤甲烷(THMs)的影响,研究表明,总有机碳(TOC)和UV-254与HAAs前体物呈正相关,而与THMs前体物的相关性较差;在pH5-10的范围内,pH值对HAAs的形成影响较小,pH值愈高HAAs总量愈小,而对THMs的形成影响较大,THMs总量随pH值的增高而增大;HAAs和THMs的形成量与投氯量、氯化时间均呈正相关;在正常气温条件下,随温度的增加而增加。 相似文献
862.
863.
针对城市生活垃圾焚烧(MSWI)过程中二(口恶)英类的生成机制以及焚烧飞灰的组成,研究了MSWI飞灰中常见的钙化合物(CaO,Ca(OH)2,CaCl2,CaSO4及Ca(NO3)2)对前生体五氯酚(PCP)及六氯苯(HCB)生成二(口恶)英类的阻滞作用.结果表明,280℃下加热2 h,Ca(NO3)2,Ca(OH)2和CaO对PCP生成二(口恶)英类的总阻滞效率分别为93.7%,80.4%和98.9%,而CaCl2和CaSO4几乎没有效果.CaO对PCP和HCB混合物生成二(口恶)英类物质同样具有良好的阻滞效果.另外,探讨了上述钙化合物对PCP及HCB生成二(口恶)英类的阻滞作用机理. 相似文献
864.
水溶液中硝基苯的超声微电场降解 总被引:13,自引:0,他引:13
研究了超声微电场中硝基苯的降解过程,并探讨了降解机理及反应历程。结果表明,硝基苯的降解符合拟一级反应,超声与微电场的耦合协同作用大大提高了硝基苯的降解效率,在槽电压10V条件下,协同作用的降解速率比简单加和作用的速率高一倍以上,经过30min协同处理后可以获得93.8%的去除率,而溶液中饱和气体种类等对降民产生一定的影响,经紫外和SMPE-GC-MS分析,推断硝基苯在电超声场作用下存在氧化还原反应与热解、自由基作用等协同作用。主要中间降解产物为苯胺、偶氮苯、1-氧,2-苯基-二氮烯、1,2-苯二甲酸二丁酯、1,2-苯二甲酸丁酯异丁酯等,最终产物为CO2、水及无机盐类。 相似文献
865.
866.
Preferences of six leaf beetle species among qualitatively different leaf age classes of three Salicaceous host species 总被引:2,自引:0,他引:2
Arsi Ikonen 《Chemoecology》2002,12(1):23-28
Summary. As Salicaceous plants produce new leaves for a prolonged period of time, they expose a wide range of differentially aged
leaves to herbivores during the growing season. In this work, I show that young leaves of three Salicaceous species, Populus tremula L., Salix phylicifolia L. and S. pentandra L., contain more nitrogen than conspecific old leaves. In P. tremula and S. pentandra young leaves also contained more low-molecular weight secondary compounds, phenolic glucosides. Leaves of S. phylicifolia did not contain phenolic glucosides in detectable amounts. Furthermore, in P. tremula and S. pentandra young leaves contained less polymeric digestability-reducing phenolics, condensed tannins, than old leaves. In S. phylicifolia, higher concentrations of condensed tannins were found in young leaves. In laboratory feeding trials with six leaf beetle
species, young leaves of the studied plants were invariably preferred in all tested herbivore × host species combinations.
In particular, it is remarkable that three leaf beetle species with known different overall relationships to phenolic glucosides
equally preferred more glucoside-containing young S. pentandra leaves over conspecific old ones. Four beetle species were found to prefer young leaves of S. phylicifolia despite the higher content of condensed tannins in young leaves. These results indicate that the general preference of leaf
beetles for young leaves of Salicaceous plants probably does not primarily result from variable distribution of secondary
compounds. Apparently, the preference for young leaves is fundamentally due to variation in leaf nutritive traits, such as
nitrogen content.
Received 9 February 2001. 相似文献
867.
Ordered parameter problems arise in a wide variety of real world situations and are dealt with extensively in the literature. Traditional frequentist methods for dealing with these problems are rather complicated theoretically, especially when sample sizes are small. Bayesian methods are not widely used because high dimensional numerical integration is often required. However, Markov chain Monte Carlo methods provide alternatives to such numerical integration and also deal with ordered parameter problems in a straightforward manner. Little is known about the situation where functions of parameters are ordered. Such problems may seem to be of little practical concern initially, but one can readily see their importance in situations where ordering is placed on the means and variances of several normal or Gamma populations. For the Gamma distribution we will present real examples where we will analyze monthly precipitation data from San Francisco, California and Oakland Mills, Iowa. For the San Francisco data we will simultaneously order both monthly precipitation means and variances. For the Iowa data we will place ordering on seasonal average while still estimating monthly means. Our results show that we would obtain sharper, more accurate inference when order restrictions are employed. 相似文献
868.
Toshiharu Akino 《Chemoecology》2002,12(2):83-89
Summary. The myrmecophilous beetles, Zyras comes (Staphylinidae) and Diaritiger fossulatus (Pselaphidae) are guests of the black shining ant Lasius fuliginosus. Host worker ants never attacked these beetles, and often gave regurgitant to Z. comes following tactile communication with the beetle. By contrast, the workers from colonies without the myrmecophiles showed
hostile responses towards Z. comes before tactile contact, but were not aware of D. fossulatus until contact. In L. fuliginosus, workers within a colony shared profiles, but the profiles differed among colonies. GC analyses showed that both Z. comes and D. fossulatus beetles had the same hydrocarbons as L. fuliginosus, and the profiles were more similar to those of the host colony workers than the foreign workers. Both Z. comes and D. fossulatus appear to imitate the hydrocarbon profile of their host workers, allowing integrating into the host nest. A Y-maze bioassay
indicated that Z. comes can follow the trail pheromone of L. fuliginosus. This suggests that Z. comes may detect other chemical signals of L. fuliginosus to keep closer interactions with the workers.
Received 22 June 2001; accepted 12 November 2001. 相似文献
869.
Yasumori?TamuraEmail author Makoto?Hattori Kotaro?Konno Yoshiaki?Kono Hiroshi?Honda Hiroshi?Ono Mitsuru?Yoshida 《Chemoecology》2004,14(2):113-118
Summary. The leaf beetle Ophraella communa infests
almost exclusively Ambrosia artemisiifolia in the fields of
Japan, even though it normally feeds on several Asteraceous
plants. A filter paper bioassay showed that the feeding of
O. communa is strongly stimulated by methanolic extracts of
A. artemisiifolia. The feeding stimulants for O. communa have
been isolated from methanolic extracts of A. artemisiifolia.
-Amyrin acetate, -amyrin acetate, 5-caffeoylquinic acid
(chlorogenic acid) and 3,5-dicaffeoylquinic acid from
A. artemisiifolia have been identified as feeding stimulants
for O. communa. Triterpenoid derivatives
(-amyrin acetate or -amyrin acetate) and caffeic acid derivatives (3,
5-dicaffoylquinic acid or 5-caffeoylquinic acid) showed
feeding stimulant activity when mixed together. 相似文献
870.
David Sillam-Dussès Etienne Sémon Céline Moreau Irena Valterová Jan Šobotník Alain Robert Christian Bordereau 《Chemoecology》2005,15(1):1-6
Summary. The diterpene neocembrene A or (1E,5E,9E,12R)-1,5,9-trimethyl-12-(1-methylethenyl)-1,5,9-cyclotetradecatriene, known as the trail-following pheromone of the advanced Termitidae Nasutitermitinae Nasutitermes exitiosus and Trinervitermes bettonianus, has been identified after SPME-GC/MS as the major component of the trail-following pheromone of the Rhinotermitidae Prorhinotermitinae, Prorhinotermes canalifrons and P. simplex. In all the other Rhinotermitidae studied until now, the major component of their trail pheromones is dodecatrienol ((3Z,6Z,8E)-dodeca-3,6,8-trien-1-ol). This biochemical data further add to the anatomical and molecular characteristics that give a special status to the taxon Prorhinotermes among Rhinotermitidae. In Prorhinotermes canalifrons and P. simplex, neocembrene A was the only secretory compound specific to the sternal gland surface that could be detected after SPME. It elicited orientation as well as recruitment behavioral effects. However, the comparison of the respective biological activities triggered by neocembrene A and by sternal gland secretion suggests that minor components of the latter are acting in synergy with neocembrene A. 相似文献