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51.
浙江海岛植物区系的研究   总被引:27,自引:1,他引:26  
浙江海岛共拥有维管植物1914种,12亚种、175变种、26变形和46栽培变种,隶属于195科、909属、植物区系组成复杂,地理在多样,纬向性明显,与邻近地区有着不同程度的联系,并以地域差异大,热带亲缘特征明显,滨海植物区系丰富和归化植物咱类繁多为特色。  相似文献   
52.
见于浙江的中国及中国大陆新记录植物   总被引:5,自引:1,他引:4  
报道了笔者于1990年至1992年间在浙江海岛(大陆岛)植被资源调查工作中发现的9个地理分布新记录,其中4种为中国分布新记录,3种及2亚种为中国大陆分布新记录。此外,还报道了同时发现的归化植物4种,其中3种为中国分布新记录,1种为中国大陆分布新记录。  相似文献   
53.
猪毛蒿精油杀虫的有效成分   总被引:24,自引:2,他引:22  
徐汉虹  周俊 《昆虫学报》1994,37(4):411-416
生物活性筛选试验表明,菊科植物猪毛蒿(Artemisia scoparia Waldst. Et Kitag)全草精油具杀虫活性。采用GC-MS方法分析了猪毛蒿精油的化学成分。共检出92个成分,鉴定了其中46个成分。通过柱层析分离出主成分,经各种波谱分析鉴定为1-苯基-2,4-己二炔。活性跟踪结果表明,l-苯基-2,4-己二炔为猪毛蒿精油中的主要杀虫成分。  相似文献   
54.
刘杏忠  沈崇尧  裘维蕃 《菌物学报》1992,11(Z1):113-115
在对北京郊区果园捕食线虫真菌的季节性分布的研究中,常观察到一种隔指孢属中的真菌,经对其形态研究确定为一新种一北京隔指孢(Dactylella beijingensis Liu, Shen et Chiu),其主要特征为分生孢子梗分枝,每个分枝顶产生单一的分生孢子,分生孢子梗向顶渐细,长79-108-137 μm,基部宽2.5-3.0 μm,顶宽1.5-2.0 μm,产孢细胞菌丝型发育,分生孢子无色,纺锤形,4-6个分隔,在分隔处稍缆缩,大小为33.5-38.0-42.0 × 7.0-8.0-8.5 μm,未见厚垣孢子产生,未见捕食线虫器官。  相似文献   
55.
稻田三化螟集团分布的初步调查及其在实用上的意义   总被引:1,自引:0,他引:1  
(一)本文就昆虫常见的数种集团分布:潘松分布、核心分布和负二项式分布的公式、性质和例子等略加讨论介绍。 (二)我们在广州附近对三化螟各时期和白穗、枯心苗的田间分布型式作了初步的调查,所得结果如下: 1.螟蛾和卵块在秧田上是随机分布的。 2.幼虫在本田分布不随机,符合核心分布和负二项式分布。 3.白穗在田间的分布不随机,1×1丛、2×2丛、……6×6丛各种取样单位型样本均符合负二项式分布,4×4丛、5×5丛和6×6丛三种取样单位型样本则更符合核心分布。 4.稻遗株内越冬幼虫分布不随机,亦不符合核心分布,但符合负二项式分布。 5.晚造本田枯心苗田间分布不随机,符合核心分布和负二项式分布。 (三)本文就昆虫集团分布型式的调查在实用上的意义,联系到三化螟来讨论,我们论及与虫害调查取样技术、田间试验设计、统计代换方法、昆虫生活习性和害虫防治等各方面的关系;其中取样技术方面,我们举出针对三化螟幼虫在本田和白穗不随机分布的取样新方法的尝试,希望对今后螟害调查工作有所帮助。 (四)最后,我们就一些昆虫分布的特殊问题加以论列,像密度对分布型式的影响,混合集团和环境因素的影响于昆虫集团分布类型等,就中说明了密度过大过 小时了解分布型式成为不必要的,因为极度的不均衡会回复为均衡状态的。  相似文献   
56.
1. The effects of flooding on top predators are poorly understood globally, but particularly in monsoonal streams. We therefore attempted to assess how inter-annual and intra-annual variations in flood magnitude affected an obligate riverine predator, the brown dipper ( Cinclus pallasii ), and its invertebrate prey, in the mountain Tachia River, Taiwan. Major flooding in one of the study years (2005) allowed an insight into the effects of abnormally large flows.
2. The abundance and biomass of insects, and the abundance of dippers, decreased steadily from 2003 to 2005 as flood magnitude grew, but then increased in 2006 when more typical discharge returned. Dipper abundance, insect abundance and insect biomass were all strongly positively inter-related, but negatively related to discharge. Insect biomass, rather than abundance, was more useful in predicting brown dipper abundance.
3. Aquatic insect composition fluctuated among sampling years, revealed by non-metric multidimensional scaling, and these fluctuations were also related to discharge. In turn, dipper abundance and the mean body size of aquatic insects declined with the shift in insect composition as flow increased.
4. These data illustrate how discharge fluctuations can have pronounced effects on top predators in streams, mediated in this case by fluctuating prey abundance. While contributions from bird movement, breeding performance and mortality were not clearly differentiated, our data reveal how dippers have strategies to accommodate varying discharge in river systems. We suggest that the effects of floods on dippers should be taken into account when using this group as indicators of river quality.  相似文献   
57.
In cranio-maxillofacial surgery planning and implant design, it is important to know the elastic response of the mandible to load forces as they occur, e.g., in biting. The goal of the present study is to provide a method for a quantitative determination of material parameters for the human jaw bone, whose values can, e.g., be used to devise a prototype plastic model for the mandible. Non-destructive load experiments are performed on a cadaveric mandible using a specially designed test bed. The identical physiological situation is simulated in a computer program. The underlying mathematical model is based on a two component, linear elastic material law. The numerical realization of the model, difficult due to the complex geometry and morphology of the mandible, is via the finite element (FE) method. Combining the validated simulation with the results of the tests, an inverse problem for the determination of Young's modulus and the Poisson ratio of both cortical and cancellous bone can then be solved.  相似文献   
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60.
1. Due to climate change, contemporary climate scenarios forecast an increase in extreme weather, which may have considerable impacts on the world's riverine ecosystems. Because the flow regime is a primary determinant of the structure and function of lotic ecosystems, changes in the weather could fundamentally alter these ecosystems through changes in hydrologic disturbance regimes. 2. In this paper, we use the abundance/biomass comparison (ABC) method, based on r/K selection theory, and event probability distribution to characterise the responses of macroinvertebrates in Taiwan mountain streams to extreme floods. 3. Severe impacts on macroinvertebrates, resulting in a large shift in community structure toward r‐selected taxa, usually were observed the year after extreme floods. 4. Macroinvertebrate communities dominated by K‐selected taxa had more individuals with traits conferring resistance to flooding disturbance, while those dominated byr‐selected taxa had more individuals with traits conferring resilience. 5. This relationship between the changes in flow regime and the ecological response of r‐ and K‐selected taxa may be exploited to understand the potential effects of flood extremes in the future, and to keep decision makers informed about the ecological consequences of climate‐mediated changes to hydrological regimes.  相似文献   
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