拟松材线虫对黑松苗的致病性

测定来源于中国、日本、韩国、加拿大、挪威和法国的20个拟松材线虫种群对2年生黑松苗的致病力。根据其致病力大小分为3类：第1类致病力很强，致死率大于85％，RHS(相关寄主适生性)系数大于100，包括法国的1个种群和中国的3个种群；第Ⅱ类有较强的致病潜能，在环境适宜的情况下可能造成严重危害，这一类数量最多，包括中国的11个种群和加拿大的1个种群；第Ⅲ类几乎没有致病力，其致死率和RHS系数都是0，包括韩国的2个种群及日本和挪威各1个种群。试验证明法国BmFr种群致死速度最快，致病力最强。黑松苗在感染拟松材线虫后，用自然界水分胁迫和PEG胁迫处理，结果表明，干旱胁迫能明显加快黑松苗死亡速度，且大大提高死亡率。提示在高温干旱的年份拟松材线虫可造成松树的大面积死亡。     

天津地区鱼塘中的HCHs残留

在天津郊区选择2处代表性鱼塘,采集了水、悬浮物、沉积物、鲫鱼和鲢鱼样品,测定了各种样品中的六六六含量,发现六六六在各相中均有较高残留。水相、悬浮物和沉积物中六六六平均浓度分别为19.2ng·L-1,1160.5ng·g-1和8.4ng·g-1。两鱼塘相差2～10倍。鱼塘各相六六六含量与周边土壤状况密切相关。各相六六六含量高的鱼塘位于农业土壤遭受严重污染的地区。污染严重的鱼塘中鱼体六六六富集量也大大高于相对浓度较低的鱼塘。采自两鱼塘的鱼的肌肉中平均六六六含量分别为71.4ng·g-1和19.7ng·g-1。以水相浓度为基准的生物富集系数分别为2.06×103和5.36×103。肝胰脏、肠、鳃、卵巢等器官都富集了更高浓度的六六六。     

Adaptive phenotypic plasticity in response to climate change in a wild bird population

Rapid climate change has been implicated as a cause of evolution in poorly adapted populations. However, phenotypic plasticity provides the potential for organisms to respond rapidly and effectively to environmental change. Using a 47-year population study of the great tit (Parus major) in the United Kingdom, we show that individual adjustment of behavior in response to the environment has enabled the population to track a rapidly changing environment very closely. Individuals were markedly invariant in their response to environmental variation, suggesting that the current response may be fixed in this population. Phenotypic plasticity can thus play a central role in tracking environmental change; understanding the limits of plasticity is an important goal for future research.     

When fear is near: threat imminence elicits prefrontal-periaqueductal gray shifts in humans

Humans, like other animals, alter their behavior depending on whether a threat is close or distant. We investigated spatial imminence of threat by developing an active avoidance paradigm in which volunteers were pursued through a maze by a virtual predator endowed with an ability to chase, capture, and inflict pain. Using functional magnetic resonance imaging, we found that as the virtual predator grew closer, brain activity shifted from the ventromedial prefrontal cortex to the periaqueductal gray. This shift showed maximal expression when a high degree of pain was anticipated. Moreover, imminence-driven periaqueductal gray activity correlated with increased subjective degree of dread and decreased confidence of escape. Our findings cast light on the neural dynamics of threat anticipation and have implications for the neurobiology of human anxiety-related disorders.     

老参地短期轮作技术体系的建立Ⅰ.人参西洋参轮作体系

老参地问题是制约参业发展的重大难题，笔者在总结前人关于老参地研究成果和经验的基础上，采取了测土施肥，有益微生物菌剂处理，酸碱度调整等土壤处理方法，成功地实现了老参地的短期再利用，建立了周期为1－3年的人参和西洋参的短期轮作体系。在处理后的老参地上种植西洋参，其长势，产量，病虫害及烧须情况，总皂苷含量等，与对照地新林土栽参无显著差异（P＞0．05）。并开展了中试规模的推广，试验结果显示，老参地短期轮作制是改造老参地的有效措施之一，该轮作技术方法应用简便，实用，可操作性强，轮作效果好。     

意向性建构原理与读者理论

现象学哲学的“意向性建构”原理的实质意义给与 :主体建构对象就是给与对象意义。这是讲求读者建构 (再创造 )文本意义一路文学理论的哲学基础     

三种植物性杀虫剂对烟草码绢金龟生物活性的初步研究

室内生物活性测定表明,印楝素对烟草码绢金龟成虫具有较强的忌避作用和拒食作用,苦楝油作用稍弱,烟株表现出药害症状,除虫菊反而具有一定的诱集和刺激取食效果,这3种植物性杀虫剂的毒杀作用均很弱.根据1%印楝素安全、活性高,但药效期较短的特点,提出了用印楝素防治码绢金龟的意见.     

Long-Term Variable Rate Lime and Phosphorus Application for Piedmont No-Till Field Crops

Variable rate (VR) fertilizer application is a paradigm with potential to improve input efficiency and farm profitability. It is widely marketed by commercial applicators in the southeastern US. However, field studies comparing VR with traditional management have not demonstrated consistent, positive results. The objectives of this study were: (1) to determine the soil impact, crop response and economic potential of VR phosphorus (P) and lime application in a North Carolina Piedmont no-till field crop system using intensive soybean [Glycine max (L.) Merr.] production and (2) to economically evaluate alternatives to standard commercial grid soil sampling for directing VR P and lime. A 23-ha long-term no-till field in the SE Piedmont was divided into 0.4ha plots assigned to either VR or uniform P and lime application. Grid soil sampling and VR P and lime application were done prior to four crops over 3 years: full season soybean, wheat (Triticum aestivum L.)–double cropped soybean, and full season soybean. Soil test P, pH and crop yield response to VR P were inconsistent. Soil pH in areas with low pH initially did increase in response to VR lime, but it took two to three applications to bring all of these areas to the target pH. Once VR-liming raised initially low soil pH to levels close to target, yield of soybean, but not wheat, were up to 0.74Mgha^–1 higher than with uniform lime. Even with significantly higher soybean yields associated with VR lime, 3 years of grid sampling and VR application were not profitable compared to uniform application. The results indicated that VR lime could be profitable if the initial grid sampling data were used either for 2 consecutive years, or if it was used to restrict future grid sampling to specific areas requiring further VR lime.     

Biosynthesis of the enediyne antitumor antibiotic C-1027

C-1027 is a potent antitumor agent with a previously undescribed molecular architecture and mode of action. Cloning and characterization of the 85-kilobase C-1027 biosynthesis gene cluster from Streptomyces globisporus revealed (i) an iterative type I polyketide synthase that is distinct from any bacterial polyketide synthases known to date, (ii) a general polyketide pathway for the biosynthesis of both the 9- and 10-membered enediyne antibiotics, and (iii) a convergent biosynthetic strategy for the C-1027 chromophore from four building blocks. Manipulation of genes governing C-1027 biosynthesis allowed us to produce an enediyne compound in a predicted manner.     

云南香料烟害虫种类及发生规律研究

通过6a系统调查,在云南省香料烟主产区烟田内共发现7目31科88种昆虫和野蛞蝓、灰巴蜗牛2种软体动物危害云南冬春香料烟。其中重要害虫是烟蚜（Myzus persicae Suizer）、棉铃虫（Heliothis arrnigera Hubner）、烟草夜蛾（Heliothis assuha Guenee）、烟草盲蝽[Cyrtopeltis tenuis（Reuter）]、野蛞蝓（Agriolimax agresfis Linnaeus）、小地老虎（Agrotis ypsilon Rottemberg）、东方蛄蝼（G．orlentalis Burmeister）、小长蝽（Nysius ericae（Schilling）]等7种。烟蚜、野蛞蝓、小地老虎均为香料烟和烤烟上的重要害虫,在发生危害时期上较一致。棉铃虫、烟草夜蛾在香料烟上危害损失较大．而在烤烟上危害较轻。东方蝼蛄和小长蝽是香料烟上的主要害虫,在烤烟上发生较少,烟草盲蝽和金龟子在香料烟上发生较少．却又是烤烟的主要害虫。