Summary Observations made on ponded white spruce wood with the electron microscope revealed that initial branching of perforation hyphae of soft rot fungi did not parallel microfibrillar orientation in the S2 wall layer but rather occurred perpendicular to this alignment. In the absence of structural evidence suggesting mechanical entry it appeared that cell wall pencetration was accomplished through enzymatic activity at the hyphal apex.The authors wish to express their thanks to Miss S. Godkin and Mr. G. Chauret for technical assistance. 相似文献
动物园是对公众进行保护教育的重要基地,游客观赏和教育项目偏好是影响游客管理决策的重要因素。本研究采用选择实验法构建深圳野生动物园庭院探秘之旅项目的随机参数模型(random parameter logit,RPL),将观看项目动物、体验项目、动物生态解说、纪念品及费用5个属性纳入评估模型,分析各属性的偏好及愿付价值(willingness to pay,WTP)。结果表明:游客希望该项目在现状基础上进行属性提升,且相对偏好于观赏多种动物以及进行深度体验,这两个属性的WTP分别为28.71和11.86元/(次·人);若项目费用升高,则游客对其选择性随之下降。利用潜在类别模型(latent class model,LCM)进行该项目游客市场区隔分析:第一个类群为偏好多样化的游客,占受访者的35.7%,第二类群为偏好单一型游客,倾向于深度体验项目,这部分游客较多,占64.3%。可开展后场参观、动物饲料制作等游客参与式深度体验项目,招募志愿者辅助完成讲解站、主题日等保护教育活动,以提高动物园对游客的吸引力。 相似文献
Menge, M., Rose, M., Bohland, C., Zschiesche, E., Kilp, S., Metz, W., Allan, M., Röpke, R., Nürnberger, M. Pharmacokinetics of tildipirosin in bovine plasma, lung tissue, and bronchial fluid (from live, nonanesthetized cattle). J. vet. Pharmacol. Therap. 35 , 550–559. The pharmacokinetics of tildipirosin (Zuprevo® 180 mg/mL solution for injection for cattle), a novel 16‐membered macrolide for treatment, control, and prevention of bovine respiratory disease, were investigated in studies collecting blood plasma, lung tissue, and in vivo samples of bronchial fluid (BF) from cattle. After single subcutaneous (s.c.) injection at 4 mg/kg body weight, maximum plasma concentration (Cmax) was 0.7 μg/mL. Tmax was 23 min. Mean residence time from the time of dosing to the time of last measurable concentration (MRTlast) and terminal half‐life (T1/2) was 6 and 9 days, respectively. A strong dose–response relationship with no significant sex effect was shown for both Cmax and area under the plasma concentration–time curve from time 0 to the last sampling time with a quantifiable drug concentration (AUClast) over the range of doses up to 6 mg/kg. Absolute bioavailability was 78.9%. The volume of distribution based on the terminal phase (Vz) was 49.4 L/kg, and the plasma clearance was 144 mL/h/kg. The time–concentration profile of tildipirosin in BF and lung far exceeded those in blood plasma. In lung, tildipirosin concentrations reached 9.2 μg/g at 4 h, peaked at 14.8 μg/g at day 1, and slowly declined to 2.0 μg/g at day 28. In BF, the concentration of tildipirosin reached 1.5 and 3.0 μg/g at 4 and 10 h, maintained a plateau of about 3.5 μg/g between day 1 and 3, and slowly declined to 1.0 at day 21. T1/2 in lung and BF was approximately 10 and 11 days. Tildipirosin is rapidly and extensively distributed to the respiratory tract followed by slow elimination. 相似文献