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991.
992.
广西单子叶植物区系及资源特点   总被引:1,自引:0,他引:1  
文和群  刘演  韦发南   《广西植物》2000,20(1):18-26
分析了广西单子叶植物的区系特征、资源类型和开发利用现状。广西单子叶植物共有 4 4科 383属 12 87种 ,其属的分布区类型主要是热带分布、温带分布、东亚分布等 ,而在这些类型中 ,典型的热带或温带种均不多 ,大部分种类都为亚热带分布型。单子叶植物的许多种类具有重要的经济价值 ,主要有药用、观赏、纤维、材用、淀粉和食用、芳香、饲料等几大类 ,在国民经济中起着重要作用。最后对资源的持续利用提出发展设想  相似文献   
993.
In this study, we review the classification of two species, Elymus hispanicus and E. marginatus, which are restricted to highly valuable and sensitive Mediterranean ecosystems. The genomic composition of the two species is analysed by in situ hybridization. In addition, lodicule morphology and foliar anatomy of both species are compared with those of E. caninus, E. repens, E. sibiricus (i.e., the type species of Elymus s.s.) and Pseudoroegneria strigosa (i.e., the type species of Pseudoroegneria). The genomic formula 2n = 8x = 56; HStStSt is proposed for E. hispanicus and 2n = 4x = 28; StSt for E. marginatus. In this latter species, the absence of the ribosomal genes in one of the two St genomes suggests that diploidization may have occurred during the evolution the species. Regarding foliar anatomy, E. hispanicus, E. caninus, E. repens, and E. sibiricus shared several characteristics, but the leaf blades of E. marginatus proved anatomically more similar to those of Ps. strigosa. The data compiled support the contention that: (1) E. hispanicus belongs to Elymus s.s.; (2) E. marginatus should be transferred to Pseudoroegneria; and (3) the morphology of the lodicules should be carefully reconsidered for appropriately describing the boundaries between Elymus s.s. and Pseudoroegneria. The new combination Ps. marginata is proposed and a detailed iconography of the plant is provided.  相似文献   
994.
Turkish representatives of the genus Rhaponticoides Vaill. are examined. A key and distribution map of Rhaponticoides species occurring in Turkey are provided for the first time. R. hierroi Ö. Eren sp. nov., from Bakacak pass in the Western Taurus range, SW Anatolia, allied to R. mykalea (Hub.-Mor.) M. V. Agab. &; Greuter is described as a species new to science and illustrated. Its habitat conditions and conservation status are considered. Pollen micrographs of R. hierroi and R. mykalea are presented using scanning electron microscopy.  相似文献   
995.
996.
目的研究高危型人乳头瘤病毒(hr-HPV)持续感染患者阴道菌群及宫颈免疫功能的变化特点,为宫颈癌的防治提供临床研究资料。方法选择286例连续2年同一型别hr-HPV阳性女性患者为观察组,124例hr-HPV阴性女性患者为对照组,比较两组患者阴道乳杆菌、支原体、衣原体、霉菌检出情况及细菌性阴道病、滴虫感染的差异,并比较两组患者宫颈分泌物物CD~+_4 T、CD~+_8 T细胞检测情况。结果观察组患者中单一型别感染214例(74.83%),2种及2种以上hr-HPV型别复合感染者72例(25.17%)。观察组患者中检出HPV16型165例(45.21%)、HPV18型36例(9.86%)、HPV31型31例(8.49%)、HPV33型22例(6.03%)、HPV51型12例(3.29%)、HPV52型75例(20.54%)、HPV53型15例(4.11%)、HPV58型9例(2.47%)。观察组患者阴道乳杆菌检出率低于对照组,而沙眼衣原体、解脲支原体、细菌性阴道病检出率均高于对照组,差异有统计学差异(P0.05)。观察组患者CD~+_4 T细胞水平(%)及CD~+_4/CD~+_8水平均低于对照组,差异有统计学意义(P0.05)。结论 hr-HPV病毒持续感染患者阴道菌群发生改变,导致宫颈微环境稳态被打破,宫颈局部免疫防御能力降低而成为宫颈癌变的主要促进因素。  相似文献   
997.
Species Distribution Models (SDMs) could be an important tool to limit search efforts by selecting the areas where field surveys are to be carried out; due to the constant decrease of financial funds, this challenging purpose is particularly necessary. In particular, these methods are useful when applied to endangered and/or rare species with a poor known distribution area, especially due to difficulties in plant detection and in reaching the study areas.We hereby describe the development of maximum-entropy (Maxent) models for the endangered yellow gentian Gentiana lutea L. in Sardinia with the aims of (i) guiding survey efforts; (ii) estimating SDMs utility by post-test species current/extinct localities through the Observed Positive Predictive Power (OPPP) values; and (iii) evaluating the influence of sample data addition. Besides the Area Under Curve (AUC) values, we used the OPPP (observed/modelled positive localities ratio) to compare results from eight, 24 and 58 presence-only data points. Even with the initial small and biased sample data, we found that surveys could be effectively guided using such methods, whereby the focus of our research was on 48% of our initial 721 km2 study area. The high OPPPs values additionally proved the reliability of our results in discovering 16 new localities of G. lutea. Nevertheless, the predictive models should be considered as a complementary tool rather than a replacement for expert knowledge.  相似文献   
998.
Goal, Scope and Background Canadian LCA practitioners currently use European or American methodologies when conducting comprehensive impact assessments, despite the fact that these methods may not be appropriate for Canadian conditions. Due to the lack of suitable models that are currently available, work has been undertaken to develop an LCIA method by adapting existing LCIA models to the Canadian context. This new method allows the characterization of 10 impact categories. Methods This project is strongly based on preliminary outcomes from SETAC recommendations for the best available practices in LCIA. Models from 3 recent LCIA site-dependent methods, EDIP2003, IMPACT2002+ and TRACI, were used in this midpoint Canadian-specific method. Characterization models were chosen based on their level of comprehensiveness, scientific sophistication and the possibility of integrating site-specific values in the models. Results and Discussion All regional and local impact categories in the method are site-differentiated. For aquatic eutrophication, (eco)toxicity and land-use impact categories, regionally-differentiated models taking into account fate and effect were already available: the parameters of these models were modified for the Canadian context. For acidification, aquatic and terrestrial eutrophication, existing models were spatially differentiated for fate: regionalization of the effect factor was also included, based on the level of sensitivity of each ecozone assessed with vulnerability factors. The default spatial resolution selected for this method was Canadian ecozones, which define spaces in an ecologically meaningful way where organisms and their physical environment evolve as a system. For each ecozone, 2334 site-dependent characterization factors have been calculated. Conclusion This LCIA methodology proposes an attractive and useful set of site-dependent characterization factors for the 15 Canadian terrestrial ecozones. Recommendation and Outlook Efforts are being carried out to extend the specificity of some factors used in eutrophication modelization. Finally, the transparency of the methodology will allow to re-calculate site-dependent characterization factors for different regions and for additional substances.  相似文献   
999.
Veterinary medicines are subject to a rigorous evaluation with regard to safety, efficacy and quality before they are licensed. For drugs used in food producing animals, it is necessary to establish what is referred to as the acceptable daily intake (ADI), this is defined as an estimate of the amount of a substance, expressed on a body weight basis, that can be ingested daily over a lifetime without appreciable risk to human health. It is necessary to determine a toxicological, pharmacological and microbiological ADI. This article describes a recently harmonized guideline that outlines the process for determining the need for a microbiological ADI and discusses the test systems that take into account the complexity of the human intestinal flora. The described process is used to address the effects of antimicrobial drug residues on human intestinal flora for regulatory purposes. The guideline does not recommend any one particular system for use in regulatory decision making but provides recommendations for a harmonized approach to establish a microbiological ADI and offers test options rather than specifying a testing regimen. The process and the challenges of this new guideline are discussed.  相似文献   
1000.
子午岭种子植物区系分析   总被引:19,自引:1,他引:19  
子午岭林区计有种子植物94科361属689种。其中裸子植物3科8属10种1变种;被子植物91科353属678种。中国特有属8个,特有种271个,子午岭特有种1个。其种子植物区系的基本特征是:植物种类相对丰富;区系成分复杂,多种成分交汇;区系组成以华北成分为主体,以温带成分占优势;南北区系成分存在差异,垂直分布带谱不明显;在中国植物区系上隶属于泛北极植物区中国-日本森林植物亚区的华北地区黄土高原植物亚地区。  相似文献   
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