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Two carbohydrases (cellulase, lysozyme), three proteases (trypsin, aminopeptidase and non-specific protease), a non-specific lipase, and semiquantitative tests of 19 digestive enzymes were assayed in different gut sections of juvenile red abalone, Haliotis rufescens, in order to identify the regions where digestion takes place and investigate the extent to which diet composition can modify the digestive capacity of abalone. The abalone were fed either fresh kelp (K) or balanced diets containing 25 or 38% crude protein for 6 months. Enzyme assays were carried out on different sections of the abalone's gut at the end of this period. On a weight-specific basis, the digestive gland was the site containing most of the enzymes. On a protein-specific basis, two main digestion regions were identified: the digestive gland-stomach region that is characterized by high activities of cellulase and lysozyme, chymotrypsin and protease, and the mouth-intestine region with a typically high activity of lipase and amino peptidase. Significant dietary effects were observed on the activity of enzymes, especially in the digestive gland. Abalone fed with 25 and 38% crude protein diets exhibited higher cellulase (39.8 ± 4.6 and 14.2 ± 0.8 mU mg− 1 protein, respectively) and lysozyme activities (88.0 ± 20.4 and 56.6 ± 15.7 U, respectively) than those fed with fresh kelp (5.5 ± 0.7 mU mg− 1 protein and 17.1 ± 1.8 U). In contrast, higher protease activity was found in kelp-fed organisms (234.1 ± 20.4 μg product/mg protein) than those fed the 25 and 38% crude protein diets (109.5 ± 20.7 and 119.5 ± 20.5 μg product/mg protein, respectively). Semiquantitative API ZYM assays resulted in no clear food-specific effects on the activity of carbohydrases, proteases, ester hydrolases or phosphohydrolases, yet organ-specific differences were conspicuous in various cases, and generally agreed with quantitative results. It is suggested that the increased carbohydrase activity exhibited by organisms fed the balanced diets resulted from a combination of an increased number of resident bacteria in the abalone's gut and facilitated contact between dietary substrates and digestive cells. The present results indicate that H. rufescens can adjust their enzyme levels in order to maximize the acquisition of dietary protein and carbohydrates. This characteristic can be advantageously used to search for suitable diets in abalone aquaculture. 相似文献
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作者采用凝胶渗透色谱（GPC）对奶油中8种有机氯农药进行样品前处理,气相色谱—电子捕获检测器进行测定,以保留时间定性,峰面积定量。在10~800 ng/mL浓度范围内,8种有机氯农药的线性良好,相关系数在0.9981~0.9996,回收率在92.4%～117.0%,RSD在1.83%～7.92%,方法检出限为0.65~2.33 μg/kg,满足奶油中有机氯农药残留检测要求。 相似文献
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马天舒 《农业图书情报学刊》2011,23(4):9-11,16
X低效率理论使我们走出了管理认识的误区,一改过去认为投入与产出是线性关系、技术关系,而从经济心理学的视角看到了人性的重要性,使得情感管理的引入成为必然,同时员工惰性区域的存在也为情感管理的介入提供了理论基础。从人性入手,尊崇张扬人性,探讨图书馆中存在的低效率问题如何用情绪识别、压力管理和情感文化的引导等方式得以解决,不仅可以实现员工个人工作绩效的提高,效率的提升,同时还能改善图书馆的整体效率。 相似文献
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沙尘暴是强风与下垫面作用的结果.在足够的风力造成不同范围和强度的沙尘暴大气过程中,对沙尘暴源区、路径区域、沙尘物质、不同产生规律、供给量进行重点分析探讨,提出以地球空间下垫面植被为主要研究对象,即认为植被覆盖度、类型、植物生长季相等同自然气象因素相互作用,对沙尘暴发生发展有制约的作用.我国北方干旱、半干旱地区,特别是在长城以北农牧交错带大面积的落叶林分结构简单,植被覆盖度低而近地面抗风能力差,尤其在落叶季节地面多为裸露,加之降水少,土壤含水量低,干燥松散,西北风强烈,沙尘迭起,造成沙尘暴大气频繁发生.因地制宜,在原有的基础上增加和发展常绿针叶林的营造,减少就地起沙（尘）,提高抗风降沙尘能力,是减弱沙尘暴侵袭的有效途径. 相似文献
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H. J. Duncan 《Potato Research》1999,42(1):25-29
Summary An appraisal was undertaken of the key factors involved in explosion and combustion processes mainly associated with the fogging
of chlorpropham formulations into potato stores. The key factors considered are source of ignition, solvents, explosive limits
of solvents, the presence and atmospheric concentrations of particulate clouds and the role of particulate material in dust
explosions. Also the sequence of events that takes place in a dust explosion, including critical concentrations of dust required
to initiate the reactions involved and the particular relevance of the above events to the behaviour of chlorpropham fogs
both at the time of application and when distributed throughout a store. The relevance of fine dust already present in the
store to the initiation of explosions, particularly secondary explosions, which are considered to be a major cause of concern
due to their severity, is also emphasised. 相似文献
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Circe E. Badillo-Salas Enrique Valenzuela-Espinoza Marco A. González-Gómez Griselda Pares-Sierra Francisco Ley-Lou Zaul Garcia-Esquivel 《Aquaculture International》2009,17(2):173-186
Two trials were carried out in the laboratory in order to assess the effect of microparticulated feed (F) and live (Thalassiosira pseudonana, M) diets on the growth of recently set (396 ± 13 μm shell height) and 2 mm Crassostrea gigas postlarvae. Different proportions of M and F (100:0, 75:25, 50:50; 25:75, 0:100) were delivered in a single dose of 3 h d−1 in trial 1. Dietary M:F proportions of 100:0, 50:50, and 0:100 were delivered as a single pulse of 8 h d−1 (P1) or two pulses of 4 h−1 (P2) in trial 2. Maximal daily M ration was 296 cells μl−1 d−1 (trial 1), 150 M cells μl−1 d−1 (trial 2), or their equivalent F dry weight. Shell height (SH), dry (DW), and organic weight (AFDW) were evaluated weekly.
Oysters from trial 1 significantly increased their size after 28 days, and exhibited no significant dietary differences in
terms of DW (1.21 ± 0.15 to 2.01 ± 0.28 mg) or AFDW (0.091 ± 0.022 to 0.166 ± 0.029 mg). Newly set postlarvae (trial 2) also
exhibited significant growth after 25 days. No dietary differences were observed in trial 2, yet P2 oysters attained significantly
higher shell heights (825–912 μm) than P1 oysters (730–766 μm) after 25 d. Pulse effects were marginally not significant in
terms of AFDW and growth rate. Together, these findings showed that balanced microfeeds have a practical potential for the
culture of early C. gigas postlarvae, when they are delivered in pulse-feeding schemes 相似文献
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绿化植物防治空气颗粒物污染研究进展 总被引：1，自引：1，他引：0
空气颗粒物污染日益加剧导致空气质量不断恶化, 严重威胁到人类健康和生存环境, 已引起世界各国的高度重视。为了减轻空气颗粒物污染危害, 利用绿化植物防治空气颗粒物污染作为一种有前景的、安全可靠的绿色治理技术应运而生。立足于国内外在绿化植物防治空气颗粒物污染方面的研究成果, 文中系统总结了绿化植物防治空气颗粒物污染的5个作用途径, 即减尘作用、滞尘作用、吸尘作用、降尘作用和阻尘作用, 并指出利用植物防治空气颗粒物污染存在的问题与研究需求, 建议今后应进一步加强植被防治空气颗粒物污染的形成机制、植物防治技术体系与治理模式等研究。 相似文献
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C. G. Athanassiou N. G. Kavallieratos F. C. Tsaganou B. J. Vayias C. B. Dimizas C. Th. Buchelos 《Crop Protection》2003,22(10):1141-1147
The insecticidal efficacy of the diatomaceous earth formulation SilicoSec® (Agrinova GmbH, Germany) against the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae) was evaluated on peeled rice, paddy rice, maize and barley in laboratory tests. SilicoSec was applied at five dose rates: 0.125, 0.25, 0.5, 1 and 1.5 g/kg of grain. The treated grains were infested with S. oryzae adults, and the weevil mortality was estimated after 24, 48 h, 7 and 14 d of exposure on treated grain. After the 14 d counts, all the exposed adults were removed and progeny production on treated grains was assessed 45 and 90 d later. Insecticidal efficacy of SilicoSec against the rice weevil was highly affected by grain type, exposure interval and dose rate. In all grains tested, longer exposure intervals increased weevil mortality. The efficacy of SilicoSec on maize was not satisfactory, given that after a 14 d exposure at the highest dose rate the mortality did not exceed 65%. Moreover, progeny production on treated maize was high, regardless of the dose rate. On the other hand, 100% of weevils were dead on barley treated with the two highest dose rates of SilicoSec, after a 7 d exposure. However, a complete suppression of progeny production on treated barley was not achieved, even at the highest dose rate. A satisfactory level of protection was recorded on paddy rice treated with 1 and 1.5 g of SilicoSec/kg. At these two rates, all adults were dead after a 7 d exposure, and no progeny were produced during the 90 d incubation period. In contrast, the mortality on peeled rice treated with 1.5 g of SilicoSec/kg did not reach 100%, even after 14 d of exposure, and a high number of progeny were recorded. 相似文献
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