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511.
本文主要从原料、生产、储存到运输各环节,分析了异噻唑啉酮的生产工艺中存在的危险性,采用的安全措施,以确保安全生产. 相似文献
512.
大学生地震灾害风险认知调查 总被引:1,自引:0,他引:1
风险认知是人们对影响日常生活和工作的各种因素的心理感受和认识,是测量公众心理恐慌的指标。开展风险认知社会调查,研究大学生对灾害风险的认知特征及其主要影响因素,不仅有利于强化大学生的地震灾害意识,而且还能为政府的综合防灾减灾规划和地震灾害管理提供决策依据。选择桂林市5所不同类型的高校进行问卷调查,通过统计分析675份有效... 相似文献
513.
日本大量废弃型社会的一般废弃物管理:政策、问题与措施 总被引:1,自引:0,他引:1
国内关于日本废弃物管理政策的研究主要侧重于其循环型社会的形成、法律体系、技术和模式;相对于日本大量废弃型社会的废弃物管理制度的研究极少,由此忽略了前后政策之间的因果关系和转变过程。文章从一般废弃物处理责任、处理技术等方面系统地考察分析了日本大量废弃型社会的废弃物管理制度,阐明大量废弃型社会废弃物管理制度的存在问题,进而说明日本为何从大量废弃型社会迈向循环型社会的原因及其途径,以期对中国废弃物管理制度建设提供借鉴参考。 相似文献
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517.
Chitobiase activity in the epidermis and hepatopancreas of the fiddler crab Uca pugilator during the molting cycle 总被引:5,自引:0,他引:5
The activity of chitobiase, also known as N-acetyl-β-glucosaminidase, in the epidermis and hepatopancreas of the fiddler crab Uca pugilator (Bosc, 1802), during the molting cycle, was investigated. A pH optimum of 5 to 6 was found for the enzymatic activity in
both the epidermis and hepatopancreas. The temperature optimum for epidermal and hepatopancreatic chitobiase activities was
50 to 60 °C. The K
m values for epidermal and hepatopancreatic chitobiase activities at 19 °C were 0.190 ± 0.027 and 0.203 ± 0.016 mM 4-methylumbelliferyl-N-acetyl-β-glucosaminide, respectively. Hepatopancreatic chitobiase activity was significantly higher than epidermal enzymatic
activity in all the molt cycle stages tested except Postmolt Stage A-B. Chitobiase activity varied significantly during the
molting cycle, with the epidermal enzymatic activity in Premolt Stage D3–4 significantly higher than in Stage C (intermolt) and Premolt Stage D0, whereas hepatopancreatic chitobiase activity in Premolt Stage D3–4 was significantly higher than in all other molt stages tested. The patterns of chitobiase activity in the epidermis and hepatopancreas
correlate well with the hemolymph titer of ecdysteroids in U. pugilator during the molting cycle; this suggests that chitobiase activity in both tissues is regulated at least in part by the steroid
molting hormones.
Received: 6 May 1998 / Accepted: 12 September 1998 相似文献
518.
Purification of contaminated paddy fields by clean water irrigation over two decades 总被引:1,自引:0,他引:1
Yiping Tai Huanping Lu Zhian Li Ping Zhuang Bi Zou Hanping Xia Faming Wang Gang Wang Jun Duan Jianxia Zhang 《Environmental geochemistry and health》2013,35(5):657-666
Paddy fields near a mining site in north part of Guangdong Province, PR China, were severely contaminated by heavy metals as a result of wastewater irrigation from the tailing pond. The following clean water irrigation for 2 decades produced marked rinsing effect, especially on Pb and Zn. Paddy fields continuously irrigated with wastewater ever since mining started (50 years) had 1,050.0 mg kg?1 of Pb and 810.3 mg kg?1 of Zn for upper 20 cm soil, in comparison with 215.9 mg kg?1 of Pb and 525.4 mg kg?1 of Zn, respectively, with clean water irrigation for 20 years. Rinsing effect mainly occurred to a depth of upper 40 cm, of which the soil contained highest metals. Copper and Cd in the farmlands were also reduced due to clean water irrigation. Higher availability of Pb might partly account for more Pb transferred from the tailing pond to the farmland and also more Pb removal from the farmland as a result of clean water irrigation. Neither rice in the paddy field nor dense weeds in the uncultivated field largely took up the metals. However, they might contribute to activate metals differently, leading to a different purification extent. Rotation of rice and weed reduced metal retention in the farmland soil, in comparison with sole rice growth. Harvesting of rice grain (and partially rice stalk) only contributed small fraction of total amount of removed metal. In summary, heavy metal in paddy field resulted from irrigation of mining wastewater could be largely removed by clean water irrigation for sufficient time. 相似文献
519.
This study investigated the effect of fertilisation and intercropping on the uptake of cadmium (Cd) by maize plants (Zea mays L. var. Guangtian-2). Maize was intercropped with soybean, peanut, chickpea, alfalfa, adzuki bean, garden pea, amaranth, Chinese mustard, and flowering Chinese cabbage. The results showed that most legumes substantially enhanced Cd uptake by maize under different fertiliser treatments. Cd accumulation in the leaf tissues of maize was increased by garden pea to 1.5 times the amount in the control (maize alone) with PK fertiliser. Maize intercropped with garden pea absorbed 1225 μg plant?1 Cd and transferred 925.9 μg plant?1 Cd to above ground tissues. Adzuki bean proved as the most valuable intercrop for enhancing Cd extraction from soil by maize owing to its relatively large maize bioconcentration factor of 5.9 and large transfer factor of 0.47 in the no fertiliser treatment. The results suggest that legumes caused a greater effect than non-legumes on Cd concentration in maize under different fertilisers; application of NPK fertiliser had positive effects on Cd level in intercropped maize. 相似文献
520.