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81.
This paper reviews the recent developments in the research of existence and uniqueness for the solutions of resistive circuits with topological approach. The relative fundamental results are demonstrated with some application examples. The physical interpretation and limitation of the topological criteria are also given.  相似文献   
82.
During the process of seismic design of structures, prediction of earthquake damage in future and estimation of economic loss after earthquake, it is important task to select appropriate variables to establish damage models for offering quantitatively the damage indices of structures under earthquake. In this article a few types of damage variables and some two-parameter damage models are first analyzed, then a new damage model on the basis of damage mechanics is proposed and at last the value of the parameter in the model is given.  相似文献   
83.
84.
A 1-cm-diameter, red, raised, cutaneous mass over the dorsal surface of the left third metacarpal of a 6-year-old neutered male yellow Labrador Retriever was aspirated. The aspirate contained cohesive clusters of cells, some containing cells with increased pleomorphism. Cellular debris (some keratinized), melanin, large numbers of macrophages, a few neutrophils, and fibroblasts were also observed. The cytologic interpretation was malignant neoplasia with histiocytic inflammation. Differentials included a carcinoma or, given the melanin pigment and variable morphology of the cells, possibly malignant melanoma. Histologically, the tumor was diagnosed as a basal cell epithelioma. Neoplasms that once were lumped into the broad histologic diagnosis of basal cell tumors have since been split into distinct entities, dependent on evidence of differentiation into epidermis, trichofollicular epithelium, or sweat or sebaceous glands. Although histologic reclassification has resulted in removal of most of these entities from the original basal cell tumor category, a cytologic diagnosis of basal cell tumor continues to be used to represent the large, heterogeneous group of epidermal, trichofollicular, and adnexal skin tumors with basal cell characteristics. The case in this report demonstrates the heterogeneity of neoplasms that may be diagnosed cytologically as basal cell tumors and supports the need for cytologic criteria and nomenclature that better reflect potential variation in tissue differentiation.  相似文献   
85.
Sustainable Forest Management (SFM) is an integral component of sustainable development. Iran is a Near East country with low forest cover. Iran uses 7 criteria and 65 indicators for regional and national monitoring of forest management. We evaluated the status of SFM in Iran, and a location imaging in its path towards SFM was provided by existing validation data and library references for the Criteria and Indicators (C&I) adopted in the Near East, We identify challenges and opportunities associated with SFM in Iran. Although the information to evaluate the trend of SFM in Iran was incomplete, we compiled some information on the basis of C&I. Comparison of some indicators with the values for the rest of the world revealed that the situation in Iran is very different. Although some indicators revealed a better situation in Iran, Iran lags the rest of the world in the implementation of SFM. Iran, like many countries, is trying hard to find ways to sustainably use its forests. Not all C&I for assessment of SFM in Iran have been determined or defined. However, a consistent and comprehensive framework of criteria and indicators to monitor progress towards SFM is being applied. Defining some C&I is still at an early stage.  相似文献   
86.
如何改变“年年植树不见树,年年造林不见林”的现象,是营林工作者一直探索和研究的问题。文中结合营林工作实际,从工程造林项目、造林规模、投资标准、造林管护等方面分析了泸西县当前造林工作上存在的困难和问题,藉此有针对性地提出控制造林规模、统一投资标准、提高造林单价、科学规划、加强新造林地管理等提高营林成效的对策及建议。  相似文献   
87.
通过对梅花种质资源以及梅花育种研究的总结,对梅花品种资源进行实地调查,得到270个梅花品种的详细性状信息;结合对花梅和果梅的性状研究分级,选出7个性状作为花果兼用梅新品种的选择标准。根据花果兼用梅新品种的选择标准,在山东青岛通过实生选育以及杂交育种等方式培育,并且通过芽变选种选出4个抗寒花果兼用梅新品种。  相似文献   
88.
水曲柳、胡桃楸等天然次生林生长情况调查   总被引:2,自引:0,他引:2  
通过标准地调查,对现有天然次生林水曲柳、胡桃楸和黄菠萝幼龄林林分特征、优良单株径级分布、生长过程进行研究,指出相应的抚育技术措施,为小兴安岭天然次生林中水曲柳、胡桃楸和黄菠萝等珍贵阔叶树种单株定向培育提供科学依据。  相似文献   
89.
在对重庆市的自然条件及社会经济状况分析的基础上,对实地调查和通过资料查阅确定的60种重庆市优良乡土树种进行了综合评价及选择。分别依据不同用途的树种制定不同的选择标准,确定出若干评价指标:对用材树种选定了速生性、丰产性、耐瘠性、抗寒性、抗旱性、抗病虫害能力、干材形质、材用价值等8个指标;对生物质能源树种选定了速生性、丰产性、耐瘠性、抗寒性、抗旱性、抗病虫害能力、多用途性、工业价值等8个指标;对景观树种选定了观叶、观花、观果、观树形、抗寒性、抗旱性、抗病虫害能力、抗污染性、吸硫能力、滞尘能力、降低噪音能力等11个指标。采用3分制并提出了每个指标的分级标准,运用层次分析法来确定各个指标的权重,根据各指标的分值和权重对60个目标树种进行了综合评价。主要结果与结论如下:(1)对20种用材树种进行综合评价的结果表明:鹅掌楸、香椿、桤木、檫木、毛桂、香樟为综合效益较高的用材树种,苦楝、川楝、厚朴、山杜英等树种次之。(2)按照20种生物质能源树种的综合评价值大小,建议选择杜仲、桤木、苦楝、刺槐、光皮树、山桐子等树种作为生物质能源林建设的主要树种。此外,灯台树、山苍子、文冠果、麻栎、栓皮栎等可以作为备选树种。(3)通过对20种景观树种的综合评价分析得出,深山含笑、四照花、珙桐、栾树、枫香、厚朴等是非常优异的观赏树种,可作为绿化骨干树种,枫杨、山桐子、红豆树、伯乐树等可作为绿化基调树种。  相似文献   
90.
Recent international summits of the International Federation of Societies of Toxicologic Pathologists (IFSTP) have debated the desirability and potential means by which the proficiency of an individual toxicologic pathologist might be recognized and communicated throughout the world. The present document describes the advantages and disadvantages of implementing such a global recognition system by any means, and provides a proposal whereby recognition might be accorded via rigorous credential review of a practitioner's education and experience.  相似文献   
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