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971.
Barium has been identified as a toxic element to most plants, although for grasses the toxicity has not been determined. A greenhouse experiment was performed to evaluate the effect of barium on growth parameters, barium accumulation, and macronutrient concentration in Tanzania guineagrass (Panicum maximum Jacq.), cultivated in nutrient solution. Five barium rates and a control were set in a complete randomized block design, with four replications. Forage yield, leaf area, barium, and macronutrient concentrations and accumulation were measured. Leaf area and yield sharply decreased with increase of barium concentration in the nutrient solution. The greatest barium concentration and accumulation were found in culms and sheaths. Toxic barium concentrations were estimated to be 1.24 mmol L?1 (170 mg L?1) in nutrient solution and 225 mg kg?1 in the diagnostic leaf, and the main symptoms of toxicity were interveinal chlorosis followed by necrotic spots in the leaf laminae of the grass.  相似文献   
972.
The influence of different combinations of illumination and shaking on the growth dynamics, pathogenicity and toxin production of the fungus Fusarium oxysporum f. sp. orthoceras, a biocontrol agent of Orobanche cumana, was studied. The fastest biomass accumulation was obtained under shaking, with or without illumination, with the highest biomass obtained after 3–4 weeks of growth. The biological activity of chloroform extracts of the culture filtrate was characterised: it contained at least two main toxic metabolites that caused necrosis and wilting of various plants and led to mortality of germinating seeds of O. cernua, O. aegyptiaca, O. ramosa and O. cumana. The highest toxic activity of the chloroform extract was obtained under illumination without shaking after 3–4 weeks of growth. The two toxic metabolites were purified and identified as fusaric acid (FA) and 9,10‐dehydrofusaric acid (DFA). Both FA and DFA production began in the first week of growth, increasing gradually to their maxima after 4 weeks. The highest level of pathogenic activity of the fungus was obtained after three or more weeks of fungal growth. It can be concluded that in order to produce high levels of toxin and pathogenic activity, the fungus should be grown under illumination without shaking for 4 weeks.  相似文献   
973.
AIM: To assess the role of surface free radicals and electromotive voltage of fibrous mineral dusts in rabbit pulmonary alveolar macrophage injuries induced by fibrous mineral dusts. METHODS: Changes in cell death ratio, malandialdehyde (MDA) and cellur electrophoresis ratio, lactate dehydrogenate (LDH)and superoxide dismitase(SOD) activities were determined, the technique of cell culture and Scanning electron Microscopy were used to examine the change of membranous permeability, charge and cellular shape. RESULTS: Fibrous wollastonite and tabulate clinoptilolite, which had no OH-, had no cytotoxicity, while fibrous sepiolite, fibrous palygorskite, fibrous brucite and chrysolite asbestos damaged pulmonary alveolar macrophages in various degrees because of the different OH- levels. All the six fibrous mineral dusts changed the cellular electrophoresis ratio. CONCLUSION: The surface electromotive voltage of fibrous mineral dusts is not an important factor, and the cytotoxicity of them may be related to OH- levels on the mineral dust surface.  相似文献   
974.
保护地栽培土壤锰毒的矫正   总被引:3,自引:0,他引:3  
模拟玻璃温室、塑料大棚硝酸钙盐积累状况,用辣椒进行盆栽试验,研究土壤锰释放规律及植物锰中毒的矫正方法。试验结果表明:添加硅、镁、铁肥和石灰,对矫正辣椒锰中毒都有一定的效果,而以施石灰法最好。  相似文献   
975.
为评价速肿消注射液的安全性 ,进行了改良 Karber氏的 LD50 检测、递增剂量的集蓄性检测、骨髓微核检测和精子畸形检测 ,使用小鼠做为实验动物。结果显示此药剂的 LD50 为994.72 mg/ kg,集蓄系数在 5.3以上 ,未出现药物耐受性现象 ;在各自的投药动物及其对照动物之间 ,骨髓微核检测的 PCE微核系数和 PCE/NCE,以及精子畸形检测结果都未出现差异。  相似文献   
976.
In broadly conceived long-term experiments, tobacco was grown in monoculture and with different crop rotations. This paper presents results in terms of the yields achieved and the major yield components for the crops grown, and the proportion of particular tobacco quality classes obtained. In addition to tobacco monoculture (initially only fertilized and later also unfertilized) as the key crop, different types of crop rotations included, besides tobacco, the following crops: winter wheat, maize, soybean, oil-seed rape, and red clover. Experiments involved two 2-year and two 4-year crop rotations, and a 3-year, a 5-year, and a 6-year crop rotation. Experiments were set up on luvic semigley on multilayered Pleistocene sands. Average 10-year results suggest that there is an advantage of crop rotation over monoculture for tobacco leaf yields. The influence of different crop rotation types on yields of other crops was variable, tending towards higher values as the number of crops in rotation was increased. Values obtained for yield components should be considered from two angles: some of the values were primarily influenced by genetic factors, while others were influenced by ecological factors, including crop rotation as an overall biological buffer. With regard to quality classes (IB-III), the growing of flue-cured tobacco in crop rotation represents a great advancement relative to its growth in monoculture, even in a narrower crop rotation.  相似文献   
977.
Citizen science is a popular method for the long-term monitoring of the distribution of wild animals. The application of these methods in different species and environments still poses challenges, especially for aquatic animals. In this study, we investigated the distribution of the Bryde's whale (Balaenoptera edeni) in the Beibu Gulf of China by using scientific boat-based surveys and citizen science approaches using 2 different methods of data collection. First, we built our mobile app (Whale Guard) and installed it on fishermen's phones. Second, we used a popular instant messaging app (WeChat) to create an online fisherman community. We found that the mobile phone app collected far fewer reports (5 reports) than the online community group (42 reports, P < 0.01). By using a variety of incentives, we maintained the fisherman's community's activity without significant user loss (P < 0.01). We also found that the locations collected by social media applications in this study were consistent with observations from scientific boat-based transect surveys. The sightings distribution of Bryde's whales differed from those in previous surveys in that they were present across larger areas. Social media apps reported that 69% of reports was confirmed by more than one person, whereas Whale Guard reports were much lower (0, P <0.001). Community-based citizen science can greatly contribute to the long-term monitoring of Bryde's whales, and it has successfully overcome the challenges of data accessibility, accuracy, and fragmentation. Our study shows how to appropriately use citizen science in different community groups and community-based approaches make them useful for large baleen whale surveys.  相似文献   
978.
长期施肥对黑土水稳性团聚体稳定性及有机碳分布的影响   总被引:4,自引:1,他引:3  
【目的】基于黑土长期定位试验平台,研究不同施肥方式下土壤水稳性团聚体和有机碳分布特征,以期揭示化肥和有机肥长期施用对土壤肥力的影响,为实现黑土合理培肥提供理论指导。【方法】依托37年黑土长期定位试验,采集CK(不施肥)、NPK(化肥)、M2(常量有机肥)、M2NPK(常量有机肥配施化肥)、M4(高量有机肥)、M4NPK(高量有机肥配施化肥)处理0—20 cm土层的土壤样品,利用湿筛法分析水稳性团聚体稳定性及有机碳在不同粒级团聚体中的分配特征。【结果】长期有机无机配施以及施高量有机肥显著降低大团聚体比例,提高微团聚体比例。长期施用化肥及常量有机肥并未明显改变团聚体的分布。M2NPK、M4NPK、M4处理的大团聚体比例较CK处理分别降低32.7%、45.8%和55.4%,而微团聚体的比例较CK处理分别提高73.2%、102.5%和123.9%。长期有机无机配施及高量有机肥的施用显著降低表层土壤水稳性团聚体的稳定性。长期施肥显著增加土壤有机碳含量,增加量为CK的1.12—2.06倍,施用有机肥及有机无机配施处理有机碳含量增加更为显著。长期施用有机肥可以增加各粒级水稳性团聚体中有机碳的含量,且随着粒径的变小,各处理有机碳含量的增加幅度逐渐减小。各处理水稳性大团聚体中有机碳含量显著高于微团聚体,这表明有机碳主要分布在大团聚体中。长期施高量有机肥及配施化肥显著降低了大团聚体对有机碳的贡献率,增大了微团聚体的贡献率,即微团聚体有机碳贡献率高于大团聚体,而其他处理大团聚体有机碳贡献率高于微团聚体。【结论】黑土长期施用化肥对团聚体的分布及团聚体有机碳含量没有显著影响。高量有机肥以及有机无机配施显著降低了大团聚体的比例,进而降低土壤团聚体的稳定性。长期施用有机肥显著增加土壤及各粒级团聚体中有机碳含量。高量有机肥及配施化肥显著降低了大团聚体有机碳贡献率,有机碳贡献率的优势粒级为微团聚体。  相似文献   
979.
ABSTRACT

Case history: Two dogs presented separately to the Small Animal Hospital, University of Florida (Gainsville, FL, USA) for ingestion of ibuprofen. The first dog ingested 561.8?mg/kg ibuprofen in addition to paracetamol and caffeine and vomited prior to admission. This patient also received fluid therapy for 8 hours prior to charcoal haemoperfusion. The second dog ingested 500?mg/kg of ibuprofen and the owners induced vomiting with hydrogen peroxide prior to presentation. Due to the severity of clinical signs, both patients were treated with charcoal haemoperfusion.

Clinical findings: The concentrations of ibuprofen in the blood of the dogs prior to treatment were 478 and 301?mg/L. During the treatment ibuprofen concentrations were reduced by 95.8% and 45.5%, respectively, with no treatment side effects and minimal clinical signs after treatment.

Diagnosis: Toxicity due to ingestion of ibuprofen toxicity that was successfully treated with charcoal haemoperfusion.

Clinical relevance: In the cases described here minimal benefit was seen after 3 hours of treatment using one haemoperfusion cartridge. This is in contrast to a previously published report in which dogs were treated for 6 hours with two charcoal haemoperfusion cartridges. This suggests that one cartridge may be sufficient. The amount of ibuprofen ingested was not a reliable predictor of the concentration in blood at the initiation of treatment. Charcoal haemoperfusion is an effective means of reducing plasma concentrations of ibuprofen, however, its use may be limited by its cost and availability.  相似文献   
980.
Phthorimaea operculella (Zeller) is a worldwide pest of potato. Plant-borne chemicals would be potential alternatives of synthetic chemical fumigants against P. operculella in the storage. Asari Radix et Rhizoma is derived from the dry roots and rhizomes of Asarum heterotropoides Fr. Schmidt var. mandshuricum, A. sieboldii Miq. var. seoulense, or A. sieboldii. In this study, fumigant toxicity and oviposition deterrent of volatile constituents from ARR, δ-3-carene, γ-terpinene, terpinolene, eucarvone, 3,5-dimethoxytoluene, and methyleugenol were tested against P. operculella. The preliminary verification of preventive and control effects of eucarvone, 3,5-dimethoxytoluene and methyleugenol on P. operculella was carried out by simulating warehouse experiments. The results indicated that the six compounds above had fumigation toxic effects on the adults and eggs of P. operculella. Among them, δ-3-carene, γ-terpinene, and terpinolene had weaker fumigation effects than those of eucarvone, 3,5-dimethoxytoluene, and methyleugenol. The LC50 values of eucarvone, 3,5-dimethoxytoluene, and methyleugenol against adult P. operculella were 1.01, 1.78, 1.51 mg/liter air, respectively. The LC50 values against egg P. operculella were 1.09, 0.55, 0.30 mg/liter air, respectively. The oviposition deterrent experiment showed that only methyleugenol (at 5 and 1 mg/ml) and eucarvone (5 mg/ml) had a substantial oviposition deterrent effect. The simulated warehouse experiment verified that methyleugenol, eucarvone, and 3,5-dimethoxytoluene protected potatoes from P. operculella and demonstrated that methyleugenol had the best preventive and control effects. It was concluded that methyleugenol was the active ingredient with the most potential in the volatiles from ARR on P. operculella control and merit further study as botanic fumigant.  相似文献   
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