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近年来,随着矿井开采向地层深处不断延伸,地层地质及水文地质条件愈加复杂,突水淹井事故呈现出上升趋势,严重影响矿井安全生产。依据矿井充水水源及水源进入矿井的途径和方式,矿井水害可划分为五种,即地表水水害、老窑水水害、孔隙水水害、裂隙水水害及岩溶水水害。加强矿井水的探测和疏放工作,提高技术和管理水平,采取相应的矿井防治水措施,是降低煤矿水害事故的必要条件。 相似文献
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凡影响生产、威胁采掘工作面或矿井安全、增加吨煤成本和使矿井局部或全部被淹没的矿井水,都称为矿井水害.近年来,随着煤田开采向地层深处不断延伸,井筒深度不断增加,地层情况越加复杂,开凿条件越加恶劣,突水淹井事故呈现出上升的趋势,严重影响和威胁矿井安全生产.本文分析了煤矿防治水工作的基本任务及对生产的影响,并结合实际例子加以说明,提出了加强煤矿防治水工作的建议. 相似文献
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在意大利中部的观察点,我们对秋季向非洲迁徙的白头鹞(Circus aeruginosus)和鹃头蜂鹰(Pernis apivorus)的跨海迁飞行为进行了研究.其中白头鹞大部分为成鸟,鹃头蜂鹰大部分是亚成鸟.研究内容包括跨海迁徙行为与风向、昼间迁徙时间、集群和年龄的关系.尽管鹃头蜂鹰不如白头鹞适合长距离跨海飞行,但它们集群迁徙时多远离海岸.两种鸟中只有很少个体选择沿海岸飞行.在无风天气,白头鹞像单独迁徙的鹃头蜂鹰一样,选择跨海飞行,而不是中途停歇或飞回陆地的断续迁徙,在逆风情况下则相反.而鹃头蜂鹰集群迁徙时的飞行策略不受风向影响.两种鸟在上午均选择跨海飞行而不是断续迁徙,下午则相反.鹃头蜂鹰的跨海迁飞行为与年龄相关,其成鸟很少跨海飞行.本研究证实鹃头蜂鹰迁徙过程中集群行为对其跨海迁飞的影响极为显著.不同年龄鹃头蜂鹰的跨海迁飞倾向不同,缺乏经验的亚成鸟和年轻成鸟选择高能量消耗的长途(跨海)飞行,而不是具中途停歇地的短距离断续迁徙. 相似文献
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许多环境因素都会影响牛黄的形成。牛经常采食含胆碱类成分高的牧草,会使牛黄的形成量降低;在干旱地区,牛的饮水受到限制,牛黄产量较高;水中含钠多时,牛黄产量少;红壤地区牛黄多,沙壤地区较少;应激反应可以促进牛黄的形成。 相似文献
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Giacomo Gianotti Alexander Valverde Melissa Sinclair Doris H. Dyson Thomas Gibson Ron Johnson 《Canadian journal of veterinary research》2012,76(4):261-267
The objective of this study was to compare the effect on the minimum alveolar concentration (MAC) of isoflurane when ketamine was administered either after or without prior determination of the baseline MAC of isoflurane in rabbits. Using a prospective randomized crossover study, 8 adult, female New Zealand rabbits were allocated to 2 treatment groups. Anesthesia was induced and maintained with isoflurane. Group 1 (same-day determination) had the MAC-sparing effect of ketamine [1 mg/kg bodyweight (BW) bolus followed by a constant rate infusion (CRI) of 40 μg/kg BW per min, given by intravenous (IV)], which was determined after the baseline MAC of isoflurane was determined beforehand. A third MAC determination was started 30 min after stopping the CRI. Group 2 (separate-day determination) had the MAC-sparing effect of ketamine determined without previous determination of the baseline MAC of isoflurane. A second MAC determination was started 30 min after stopping the CRI. In group 1, the MAC of isoflurane (2.15 ± 0.09%) was significantly decreased by ketamine (1.63 ± 0.07%). After stopping the CRI, the MAC was significantly less (2.04 ± 0.11%) than the baseline MAC of isoflurane and significantly greater than the MAC during the CRI. In group 2, ketamine decreased isoflurane MAC (1.53 ± 0.22%) and the MAC increased significantly (1.94 ± 0.25%) after stopping the CRI. Minimum alveolar concentration (MAC) values did not differ significantly between the groups either during ketamine administration or after stopping ketamine. Under the study conditions, prior determination of the baseline isoflurane MAC did not alter the effect of ketamine on MAC. Both methods of determining MAC seemed to be valid for research purposes. 相似文献
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Observations on the use of tetracycline and niacinamide as antipruritic agents in atopic dogs 下载免费PDF全文
Beningo KE Scott DW Miller WH Rothstein E 《The Canadian veterinary journal. La revue veterinaire canadienne》1999,40(4):268-270
Tetracycline and niacinamide were administered in combination to 19 atopic dogs to determine their effectiveness in controlling pruritus. The pruritus was controlled successfully in only one dog. One dog experienced diarrhea that was severe enough to warrant stopping the medication. 相似文献