用颗粒离散元法模拟料仓卸料过程

采用颗粒离散元法模拟了无粘软颗粒和粘连性硬颗粒在平底仓卸料全过程,并与已完成的无粘硬颗粒结果比较。发现颗粒的材料模量对卸料特性影响甚小,而颗粒表面粘连性对卸料流率有显著的迟滞作用。在大出口情况,结拱不易形成,并出现颗粒自由下落现象。     

宜黄自然保护区华南虎野生种群调查及栖息地评价

江西省宜黄县省级自然保护区以华南虎 (Pantheratigrisamoyensis)为主要保护对象 ,是近几年发现华南虎证据最多的区域 .中美华南虎联合考察队于 2 0 0 1年 3 7月对该保护区进行了调查 ,采用访问调查法、样线调查法、痕迹调查法、红外线自动照相技术等目前国际国内通用的方法和技术 .该次考察虽未证实该区域华南虎存在的确切信息 ,但较系统地调查了该区域的生境资料 ,初步评价了华南虎的生存环境 .其结论为 ,由于乱捕滥猎、过度的经济活动、栖息地缩小和破碎化是导致目前华南虎极度濒危甚至难觅其踪迹的主要原因 .该区域历史上是华南虎较多的区域 ,目前仍具备华南虎生存的基本条件 .     

Stream sediment composition: An aid to water quality assessment

The trace element composition of stream sediments from catchments contaminated by past and present mining activities has been used to indicate the trace element status of associated waters. The paper discusses the possibility of using geochemical reconnaissance maps based on the analysis of stream sediments as an ancillary aid to water quality evaluation.     

正确看待有机园艺

我不是有机园艺的反对者,只是觉得这种回归自然的方式有时候会让人不知所措。在美国当地的花园中心(Garden Center),几乎没有商品不标榜"纯天然"、"对环境安全",甚至"有     

Sarcosporidiosis—A review

Summary Sarcosporidia are protozoal parasites which develop in the cross-striated fibres of skeletal, tongue, oesophageal and cardiac muscle. The affection occurs in many species of vertebrate animals and birds, has a world-wide distribution, but rarely has any untoward effects on the host it parasitizes. The economic importance of the sarcosporidia is that carcases found severely infected on meat inspection are condemned.

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Sumario Los Sarcosporidia son parásitos protozoarios que desarrollan en las fibras estriadas de los músculos del esqueleto, lengua, esófago y músculo cardiaco. El proceso ocurre en muchas especies de animales vertebrados y aves; tiene una distribución mundial, pero raramente tiene efecto nocivosen el hyesped parasitado. La importancia económica de los sarcosporidios radica en el hecho que las carcasas severamente infectadas son condenadas, al momento de la inspección de carnes.

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Résumé Les Sarcosporidies sont des protozoaires parasites qui se développent dans les fibres musculaires striées, la langue, l'oesophage et le muscle cardiaque. Cette affection existe chez beaucoup de mammifères et chez des oiseaux; elle a une large distribution mondiale mais a rarement des effects néfastes sur l'h?te parasité. Les sarcosporidies ont une, importance économique du fait des saisies des carcasses fortement atteintes, à l'occasion de l'inspection des viandes.

     

Prevalence and risk factors associated with outcome of surgical removal of pedunculated lipomas in horses: 102 cases (1987-2002)

OBJECTIVE: To determine the prevalence of pedunculated lipomas and identify risk factors affecting postoperative complications and survival in horses at a veterinary teaching hospital undergoing surgery for colic caused by pedunculated lipomas. DESIGN: Retrospective study. ANIMALS: 102 horses with a diagnosis of pedunculated lipoma. PROCEDURE: Age, breed, weight, and sex of horses with pedunculated lipomas were compared with the total equine hospital population and the population of horses admitted for abdominal surgery during the same period. Follow-up information was obtained by reevaluation or contact with owners via telephone or written request. RESULTS: Prevalence of pedunculated lipomas as a reason for abdominal surgery in horses, compared with the population of horses with and without lipomas admitted for abdominal surgery, was 10%. Castrated male Saddlebred and Arabian horses > 14 years old were identified as being at risk for developing pedunculated lipomas. Postoperative complications were detected in 72% of horses with pedunculated lipomas. Variables associated with low survival rates included surgery before 1992, heart rate > 80 beats/min, abnormal color of abdominal fluid, pale mucous membranes, surgery requiring intestinal resection, and inability to attain a mean arterial pressure > or = 100 mm Hg. Horses undergoing surgery from 1992 to 1996, weighing < 409 kg (900 lb), or requiring jejunojejunal anastomosis had a high survival rate. CONCLUSIONS AND CLINICAL RELEVANCE: Although many of the variables reflected the health of the horse at the time of surgery, results may help veterinarians recognize risk factors associated with development of pedunculated lipomas and better predict the outcome of horses undergoing surgery for colic caused by pedunculated lipomas.