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41.
生物信息学中,发现、鉴别新基因是承上启下的一步,它既承接了过往如“基因组测序”的工作,又是未来“后基因时代”研究的基石.“基因电脑克隆”是利用计算手段发现、鉴别新基因的方法,SiClone软件实现了“基因电脑克隆”功能.本文对SiClone软件操作的数据库提出并行处理方案,并详述了基于MPI(message passing interface)平台实现的并行优化版本PSiClone.根据已得到的EST数据库,展示了软件并行版PSiClone的运行性能,试验数据库EST序列条数仅仅是NCBI(The National Center for Biotechnology Information)dbEST庞大数据库的很小部分,这也暗示我们软件的并行工作对于大数据库的比较和运算将更有应用前景.  相似文献   
42.
In the 1990s during wet seasons a new disease causing brown leaf spots on lettuce (Lactuca sativa) was found for the first time in many lettuce‐growing areas of Austria and Germany. The causal agent, a new pathogenic species called Septoria birgitae, may be responsible for total crop loss. To study how temperature, inoculum density and leaf wetness period influence disease incidence and severity of leaf spot on lettuce caused by S. birgitae, we carried out in vivo experiments in growth chambers and in the field. Additionally, we evaluated the relevance of infected plant debris acting as a primary inoculum source in soil for subsequent crops. S. birgitae produces spores over a wide temperature range between 5°C and 30°C, and can infect plants at temperatures between 10°C and 30°C, with an optimum between 20°C and 30°C. Spores of S. birgitae at a density of at least 103 conidia mL–1 are essential for disease outbreak on lettuce. Because leaf wetness is crucial for releasing conidia from pycnidia, we studied the impact of leaf wetness duration on disease development under various temperature conditions. For relevant leaf spot disease development on lettuce in vivo, a leaf wetness duration of at least 24 h and temperatures higher than 10°C were necessary. Leaf spot disease development in the field required several leaf wetness periods longer than 20 h at approximately 15°C at the beginning of crop cultivation. Incorporating S. birgitae infected plant debris in soil as a primary inoculum was not relevant for leaf spot disease outbreak in the next year. However, in cases of continuous cropping of lettuce on the same field and in the same season, Septoria‐infected lettuce debris may become more relevant.  相似文献   
43.
以模式作物烟草(Nicotiana tabacum)为试材,采用水培试验,以营养液含钼0.20mg·kg-1作为对照(CK),0mg·kg-1为缺钼处理(T),研究缺钼对旺长期烟草光合色素、叶绿素荧光日变化和叶片细胞亚显微结构的影响,以揭示钼对旺长期烟草光合作用影响及其作用机理。结果显示:(1)缺钼处理烟叶的叶绿素和类胡萝卜素含量显著低于施钼烟叶。(2)缺钼烟叶的日净光合速率(Pn)下降早于对照,而且回升较慢;施钼烟叶的Pn呈典型双峰日变化。(3)施钼烟叶的最大光化学效率(Fv/Fm)比较稳定;光合电子传递速率(ETR)和光合有效量子产量(Y)在14:00较低,16:00略有回升;初始荧光(F0)和非光化学猝灭系数(NPQ)在12:00~14:00略微增加,18:00恢复到8:00的水平。缺钼烟叶Fv/Fm在12:00明显降低,16:00后开始有所回升;10:00后,其ETR和Y开始下降,F0和NPQ急剧增加,16:00后开始有所降低,18:00未恢复到8:00的水平。(4)缺钼烟叶细胞亚显微结构的基粒片层和基质片层膨胀变形、松散,淀粉粒少而且发育差;施钼烟叶片层结构排列整齐,淀粉粒发育好。研究表明,旺长期缺钼烟叶的光合色素含量降低,细胞结构发育不良,叶绿素荧光受强光和高温反应敏感,净光合速率降低,光合碳同化产物减少。  相似文献   
44.
The free-running period is regarded to be an exclusive feature of the endogenous circadian clock. Changes during aging in the free-running period may therefore reflect age-related changes in the internal organization of this clock. However, the literature on alterations in the free-running period in aging is not unequivocal. In the present study, with various confounding factors kept to a minimum, it was found that the free-running periods for active wakefulness, body temperature, and drinking behavior were significantly shorter (by 12-17 min) in old than in young rats. In addition, it was found that the day-to-day stability of the different sleep states was reduced in old rats, whereas that of the drinking rhythm was enhanced. Transient cycles were not observed, nor were there any age-related differences in daily totals of the various sleep-wake states. The amplitudes of the circadian rhythms of active wakefulness, quiet sleep, and temperature were reduced, whereas those of paradoxical sleep and quiet wakefulness remained unchanged.  相似文献   
45.
2007-2012 年佛冈县稻飞虱灯下发生期及种群数量动态分析   总被引:1,自引:0,他引:1  
明确佛冈县稻飞虱灯下发生期及灯诱种群数量动态,对当地稻飞虱的预测预报和防治工作具有重要意义.根据佛冈县2007-2012年白背飞虱和褐飞虱的灯诱数据,分析了该县白背飞虱和褐飞虱的灯下始见日、终见日、发生期及灯诱量等.结果表明在佛冈地区,白背飞虱和褐飞虱混合发生;白背飞虱的灯下始见日集中在3月底至4月上旬,明显比褐飞虱早一个月,终见日均在10月下旬,差别不大;稻飞虱在早稻和晚稻期间均会出现大小不一的灯诱高峰,早稻期间白背飞虱高峰期集中在5月中旬至6月中旬,褐飞虱灯诱高峰期较迟,主要在7月中旬前后;晚稻期间向背飞虱高峰期大多在9月上旬至10月上旬,褐飞虱高峰期在10月份;早稻期间,白背飞虱的灯诱量占绝对优势,晚稻期间褐飞虱的灯诱量上升,与白背飞虱灯诱量基本持平.因此,佛冈县稻飞虱的灯下发生期及种群数量动态在一定程度上可反映当地稻飞虱的发生情况.  相似文献   
46.
以亲缘关系极近的近缘种类群、中等距离的远缘种类群为对象,分析生物钟基因period的Thr-Gly区段的分子进化特征,发现Thr-Gly区段在果蝇和部分双翅目昆虫中未曾经历性选择和其他定向的正选择。Thr-Gly区段在果蝇nasuta亚群中的分子进化速率为10.4×10  相似文献   
47.
Biological characteristics of Pentaceropsis recurvirostris, Paristiopterus gallipavo and Parazanclistius hutchinsi were determined from commercial gillnet samples from temperate south‐western Australian coastal waters. Growth zones in otoliths, with more than a few such zones, were readily detectable only after the otoliths had been sectioned. Visual analyses and modelling of the trends in marginal increments on sectioned otoliths demonstrate that these opaque zones are formed annually. Maximum ages of 55, 36 and 49 years, derived for P. recurvirostris, P. gallipavo and P. hutchinsi, respectively, reflect relatively low mortalities. These longevities greatly exceed those estimated, using otoliths, for Pentaceros wheeleri and Pentaceros richardsoni, which belong to the other pentacerotid subfamily. These differences may be due to the counts of ‘daily’ growth zones in sectioned otoliths of P. wheeleri not representing the complete age range of that species and the zones detected in whole otoliths of P. richardsoni not constituting the complete range of annually‐formed zones. Pentaceropsis recurvirostris, P. gallipavo and P. hutchinsi recruited into the fishery in the sampling area as 2–3 year‐old fishes. Pentaceropsis recurvirostris and P. hutchinsi exhibited little or no subsequent growth throughout the remainder of their protracted life, whereas, P. gallipavo continued to grow for c. 5 years and then underwent little further growth. Spawning of P. recurvirostris and P. hutchinsi peaked in the austral winter and autumn, respectively, but in the austral spring and summer with P. gallipavo, which is more typical of temperate species. Although the females of P. gallipavo and P. hutchinsi were mature, this did not apply to a few P. recurvirostris, some of which were >20 years old, implying that any given female of this species does not always spawn every year. Ovarian mass greatly exceeded testis mass, indicative of pair spawning, which is consistent with field observations. In contrast to P. recurvirostris and P. hutchinsi, the sex ratio was heavily biased towards males and the spawning period longer in P. gallipavo, suggesting that selection pressures for spawning success were greater for this latter species.  相似文献   
48.
采用反相高效液相色谱法对川西獐牙菜中6种药用成分不同生长期的含量进行了测定.色谱柱为Kro-masilC18 250mm×4.60mm,5μm ,流动相为甲醇-0.02%的磷酸水溶液,检测波长260nm.该方法具有很好的线性关系和回收率.结果显示,川西獐牙菜全草的最佳采收期为9月中旬 花果期 .  相似文献   
49.
从保护生物多样性角度谈频振式杀虫灯的应用   总被引:24,自引:3,他引:24  
张广学  郑国  李学军  卜军 《昆虫知识》2004,41(6):532-535
频振式杀虫灯诱杀昆虫的效果较好 ,但是在诱杀昆虫的过程中选择性不强 ,在诱杀害虫的同时对天敌和其它无益无害昆虫也具有较强的杀伤能力。为了更好地保护自然生态平衡和生物多样性。作者建议在自然生态条件好的地区最好不要使用频振式杀虫灯 ,在适合使用的地区应该事先做好害虫监测 ,应在防治适期使用。  相似文献   
50.
熊愫兵  李中艳  付静  柴进  张婷  房殿春 《生物磁学》2013,(36):7104-7107
目的:分析失代偿期肝硬化患者感染的相关危险因素和临床特点。方法:回顾性分析我院2012年4月--2013年4月住院的197例肝硬化失代偿期患者,比较感染患者与非感染患者的年龄、性别、肝功能分级、白细胞水平、门静脉内径、肝硬化并发症、侵入性操作措施、应用抗菌药物、住院时间等差异。结果:197例患者中发生感染的56例,其中以呼吸道和腹部感染为主。统计发现肝功能分级、白细胞水平、侵入性操作、住院时间及抗菌药的运用等与感染因素有关(P〈0.05)。结论:引起失代偿期肝硬化感染的危险因素是多方面的,临床特点也较突出,需要我们采取防措施去避免。  相似文献   
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