995 resultados para 280
Resumo:
银染色观察发现, 我国8种大鼠银染核仁组织者Ag-NORs的数目和分布均存在一定的差异, 在不同细胞之间和同源染色体之间均呈现较为明显的多态性以及Ag-NORs的联合现象和异形现象。模糊聚类分析, 获得8种大鼠的聚类分析支图, 结合地理分布等指标对其分类地位和相似关系作了初步探讨。图1表5参30
Resumo:
采用固相微萃取(SPME)高效液相色谱法(HPLC)同时测定了水中苯酚、4-硝基酚、3-甲基酚、2,4-二氯酚、2,4,6-三氯酚、五氯酚等六种酚类化合物的含量.采用ZORBOX SB-C18柱,以甲醇-1%乙酸水溶液为流动相进行梯度洗脱,流速为1.0 mL/min.紫外检测波长为254、280 nm.六种酚类化合物的检出限为0.31~1.90μg/L,加标回收率为88%~103%.该方法操作简单,能快速、准确地检测水中的酚类化合物.
Resumo:
通过在思茅地区进行的2次(1994年及1995年)枯草期补饲孕羊后春羔初生重和生长情况的观察,以及对春羔进行寄生虫驱治试验的结果,分析并得出当地“咕公羊”(春羔)死亡率高和生长缓慢的主要原因是:怀孕期母羊的营养不良和羔羊感染寄生虫所致。通过在枯草期补饲和适时给羊只驱虫可降低春羔死亡率和加快春羔的生长。
Resumo:
中国有280种左右两栖动物,分隶3目11科。介绍10个物种的形态特征和部分习性及分布等。
Resumo:
In recent years, many industrial firms have been able to use roadmapping as an effective process methodology for projecting future technology and for coordinating technology planning and strategy. Firms potentially realize a number of benefits in deploying technology roadmapping (TRM) processes. Roadmaps provide information identifying which new technologies will meet firms' future product demands, allowing companies to leverage R&D investments through choosing appropriately out of a range of alternative technologies. Moreover, the roadmapping process serves an important communication tool helping to bring about consensus among roadmap developers, as well as between participants brought in during the development process, who may communicate their understanding of shared corporate goals through the roadmap. However, there are few conceptual accounts or case studies have made the argument that roadmapping processes may be used effectively as communication tools. This paper, therefore, seeks to elaborate a theoretical foundation for identifying the factors that must be considered in setting up a roadmap and for analyzing the effect of these factors on technology roadmap credibility as perceived by its users. Based on the survey results of 120 different R&D units, this empirical study found that firms need to explore further how they can enable frequent interactions between the TRM development team and TRM participants. A high level of interaction will improve the credibility of a TRM, with communication channels selected by the organization also positively affecting TRM credibility. © 2011 Elsevier Inc.
Resumo:
Do hospitals experience safety tipping points as utilization increases, and if so, what are the implications for hospital operations management? We argue that safety tipping points occur when managerial escalation policies are exhausted and workload variability buffers are depleted. Front-line clinical staff is forced to ration resources and, at the same time, becomes more error prone as a result of elevated stress hormone levels. We confirm the existence of safety tipping points for in-hospital mortality using the discharge records of 82,280 patients across six high-mortality-risk conditions from 256 clinical departments of 83 German hospitals. Focusing on survival during the first seven days following admission, we estimate a mortality tipping point at an occupancy level of 92.5%. Among the 17% of patients in our sample who experienced occupancy above the tipping point during the first seven days of their hospital stay, high occupancy accounted for one in seven deaths. The existence of a safety tipping point has important implications for hospital management. First, flexible capacity expansion is more cost-effective for safety improvement than rigid capacity, because it will only be used when occupancy reaches the tipping point. In the context of our sample, flexible staffing saves more than 40% of the cost of a fully staffed capacity expansion, while achieving the same reduction in mortality. Second, reducing the variability of demand by pooling capacity in hospital clusters can greatly increase safety in a hospital system, because it reduces the likelihood that a patient will experience occupancy levels beyond the tipping point. Pooling the capacity of nearby hospitals in our sample reduces the number of deaths due to high occupancy by 34%.