西北干旱半干旱区耕地面积变化与人口、经济发展的相关关系研究——以甘肃省为例

基于甘肃省1997-2006年耕地十年变化的数据,研究了甘肃省经济发展过程中耕地面积变化的过程,并运用统计分析方法,对近十年来耕地变化与人口以及固定资产投资、人均GDP等经济指标进行相关分析.结果表明:耕地面积与人口呈相反趋势,与固定资产投资、人均GDP、城市化水平呈正" U"型三次曲线相关,即固定资产投资总额、人均G...     

Spontaneous mosaicism occurred in normally fertilized and gynogenetically induced progeny of the kokanee salmon Oncorhynchus nerka

ABSTRACT:   In normally fertilized progeny of the kokanee salmon Oncorhynchus nerka , DNA content flow cytometry revealed that all the externally normal embryos were diploid, whereas abnormal embryos exhibited haplo-diploid, diplo-tetraploid and haplo-diplo-tetraploid mosaicisms, together with a few haploid and diploid individuals. When gynogenetic development was artificially induced by fertilization of eggs obtained from a female of the same kokanee brood stock with UV-irradiated sperm, haplo-diploid mosaics appeared most frequently. These mosaics were likely to happen by certain cytological events, such as meiotic or mitotic errors during the process of maturation, fertilization or early cleavage.     

藏东南德姆拉山东坡及察隅河谷的蚂蚁群落

蚂蚁隶属于昆虫纲( Insecta)膜翅目(Hymenoptera)蚁科(Formicidae),是地球上分布最广泛、种类和数量最多的社会性昆虫,除了地球的两极及雪线之上,陆地上几乎都有蚂蚁的踪迹.蚂蚁不仅具有药用、食用及研究价值,还有改良土壤、帮助植物传粉、传播植物种子、防治害虫等功用(徐正会,2002).此外蚂蚁还是指示生物多样性和环境变化的重要类群(Andersen,1990;1995;Alonso,2000;Kaspari et al.,2000). 20世纪至今,国内有关蚂蚁物种多样性的研究报道呈增长趋势.国外蚁类学家Mayr (1889)、Forel (1906)、Ruzsky (1914)、Donisthorpe (1929)、Menozzi(1939)、Eidmann(1941;1942)、Dlussky( 1965)、Collingwood (1970)、Kohout (1994)、Radchenko等(1999)等报道过西藏的蚂蚁种类及地理分布.我国蚁类学家唐觉等( 1982;1993)、周善义( 2004)分别报道过西藏墨脱、喜马拉雅山区和雅鲁藏布大峡谷的蚂蚁(于娜娜等,2011).     

Compatibility between <Emphasis Type="Italic">Calpurnia aurea</Emphasis> leaf extract,attraction aggregation,and attachment pheromone and entomopathogenic fungus <Emphasis Type="Italic">Metarhizium anisopliae</Emphasis> on viability,growth, and virulence of the pathogen

Metarhizium anisopliae sensu stricto (ss) (Metsch.) Sorok. isolate ICIPE 07 is being developed as biopesticide for the control of ticks. In addition, leaf extracts of Calpurnia aurea Benth, and the attraction aggregation and attachment pheromone (AAAP) are being used as ticks’ attractant. The three agents are being considered for use in combination in an autodissemination approach, whereby ticks that are attracted to semiochemicals are infected with the inoculum. Experiments were therefore conducted to evaluate in vitro the compatibility between C. aurea, AAAP, and the M. anisopliae on vegetative growth, conidial production, and spore viability. Calpurnia aurea leaf extract was compatible with the fungus at all the concentrations tested, whereas AAAP inhibited all the fungal growth parameters. The virulence of M. anisopliae formulated in emulsifiable extracts of C. aurea was also tested against different developmental stages of Rhipicephalus appendiculatus in laboratory bioassays. No significant differences in virulence were observed between M. anisopliae applied alone and M. anisopliae formulated in different concentrations of C. aurea leaf extracts. These results suggest that C. aurea leaf extracts is compatible with M. anisopliae and could be mixed together for “spot-spray” treatments as low-cost and environmental-friendly technology to control ticks in grazing field, while AAAP should be used separately.     

油松过密林分超强度间伐试验研究

通过对油松(Pinus tabuliformis)过密林分采取超强度间伐试验,结果表明,对过密林分实施超强度间伐不仅可极大地改善林木生长环境和卫生状况,而且能促进保留林木快速生长发育,对提高林木质量、增加单位面积林木生长蓄积,防止病虫害的发生和入侵都十分有利,超强度间伐27年后,Ⅰ、Ⅱ级木所占比例为71%～75%,比常规间伐区高46～48个百分点。     

旋转轴唇形油封泵汲效应

基于旋转轴唇形油封的微观和宏观泵汲原理,应用流体动力学一维雷诺方程及油膜厚度表达式,假设唇口接触压力分布近似为三角形推导出泵汲率方程,计算分析了安装相关参数(接触宽度、抱轴力)、结构参数(油侧唇角、空气侧唇角)及运行参数(转速)等对泵汲率和密封性能的影响.结果表明,优化前和优化后2种油封模型的泵汲率均大于0,满足密封要求.抱轴力一定时,接触宽度增加,泵汲率增加;接触宽度不变时,随抱轴力的增加,油封唇口摩擦扭矩增大,泵汲率逐渐变小,但变化幅度不大.空气侧唇角不变时,随着油侧唇角增加,2种油封的泵汲率均显著增加;油侧唇角一定时,空气侧唇角增加,泵汲率逐渐减小.随着转速增大,唇口动压效应增强,泵汲率随之增大.2种油封相比较,优化后油封明显具有更好的泵汲效应和密封性能.     

不同玉米品种与大豆带状复种模式氮素吸收利用分析

为科学利用大豆的生物固氮作用,筛选玉米大豆带状复种模式下最佳组合,本试验以‘大丰26’(IC1)、‘大丰30’(IC2)、‘强盛51’(IC3)及‘强盛388’(IC4)为实验材料,采用单因素随机区组长期定位试验测得各玉米品种氮素利用及产量数据。结果表明：玉米大豆带状复种模式下玉米产量及地上部生物量均表现为IC2>IC3>IC4>IC1 (P<0.05)。相比IC1、IC3及IC4处理,IC2处理下年平均氮素积累量、氮素农学利用率、氮素生理利用率及氮素偏生产率分别显著增加了10.8%、11.0%、15.3%;17.3%、32.3%、26.2%;36.8%、34.9%、30.1%;18.8%、20.6%、12.5%,而IC2处理年平均氮素收获指数较IC4处理显著降低4.6个百分点(P<0.05);此外,氮素农学利用率、氮素生理利用率、氮素收获指数与产量呈极显著正相关(P<0.05)。综合表明,‘大丰30’与大豆带状复种能够显著提高作物产量及氮素利用率,可作为山西省最优组合推广。