传粉昆虫的研究现状及存在的问题

传粉昆虫种类繁多,其传粉特性和效果各不相同.目前,国外关于蜜蜂、熊蜂、壁蜂对农作物授粉的研究较为系统,措施得当,且已建立了工厂化周年繁育和出售的专业公司.国内对传粉昆虫的研究较为滞后,虽然在野生种类的驯养、人工繁殖方面取得突破,但要实现规模化饲养还存在不少问题.尤其要在传粉昆虫资源调查、生物学和生态学研究、人工繁殖、定向育种、病虫害防治、野生资源驯化和管理、授粉技术的改进等方面的研究上投入更大的力量,尽快缩短与发达国家的距离,让传粉昆虫更好地服务于农业生产.     

核桃优良品种雌雄花授粉活力的研究

在核桃花期,柱头的可授性和花粉活力直接决定着座果率和当年产量。本文采用具有代表性的核桃优良品种‘温185’、‘强特勒’和‘清香’,在记录柱头授粉受精形态变化的同时,用联苯胺--过氧化氢法确定了柱头的可授时期;用MTT染色法确定了花粉活力期限和花粉活力最高的条件和时期。结果表明：柱头可授时期在柱头微张至出现棕色条纹之间,...     

Past glacial activity in the canadian high arctic

Field observations on northeast Ellesmere Island indicate that the maximum advance of the northwest Greenland Ice Sheet was about 100 kilometers beyond its present margin. This occurred before the outermost Ellesmere Island ice advance, which took place more than 30,000 years before present (B.P.). Recession from the Ellesmere Island ice margin began at least 28,000 to 30,000 and possibly more than 35,000 years B.P. During this sequence of glacial events, significant land areas remained free of ice. The late Wisconsin ice extent along both northeast Ellesmere Island and northwest Greenland was extremely limited, leaving an ice-free corridor along Kennedy and Robeson channels. Recession from these ice margins is indicated by initial postglacial emergence around 8100 to 8400 years B.P. The relatively minor extent of late Wisconsin ice in the High Arctic probably reflects a period of extreme aridity occasioned by the buildup of the Laurentide Ice Sheet to the south.     

常见庭院花木介壳虫的识别及综合防治措施

介绍吹绵蚧、粉蚧、盾蚧、蜡蚧、绵蚧及球坚蚧等几种庭院花木常见介壳虫的形态特征、识别方法、发生规律及为害症状,并总结了检疫工作、栽培管理、化学防治、生物防治等综合防治措施。     

鹤望兰的自花与异花授粉研究

珍稀名贵花卉鹤望兰是典型的鸟媒植物 ,引种到我国栽培 ,由于没有蜂鸟 ,必须人工授粉才能结实 .为了研究人工授粉的效果 ,提高鹤望兰的授粉成功几率 ,对授粉的时间、同一花序的不同花朵、自花、异花等进行比较试验 .结果表明 :①在厦门地区 ,4～ 7月、9～ 11月进行人工授粉效果最好 ;②异花授粉的结果率明显高于自花授粉 ,异花授粉的结果率平均为 91 75 % ,自花授粉仅为 40 76 % ;③异花授粉的单果种子数为 2 4 5个、自花授粉为 10 4个 ,两者存在明显差异 ;④同一花序的各花朵间异花授粉结果率无差异 ,而进行自花授粉各花朵间存在明显差异 ;⑤同一花序的不同花朵间授粉结实的单果种子数无差异     

Protactinium-231 and thorium-230 abundances and high scavenging rates in the western arctic ocean

The Canadian Basin of the Arctic Ocean, largely ice covered and isolated from deep contact with the more dynamic Eurasian Basin by the Lomonosov Ridge, has historically been considered an area of low productivity and particle flux and sluggish circulation. High-sensitivity mass-spectrometric measurements of the naturally occurring radionuclides protactinium-231 and thorium-230 in the deep Canada Basin and on the adjacent shelf indicate high particle fluxes and scavenging rates in this region. The thorium-232 data suggest that offshore advection of particulate material from the shelves contributes to scavenging of reactive materials in areas of permanent ice cover.     

Spiroplasmas and acholeplasmas: multiplication in insects

The helical wall-free microorganism, Spiroplasma citri, which is associated with citrus stubborn, a disease with no known vector, multiplied in the leafhopper vector of corn stunt but multiplied to higher titer in the vector of aster yellows and decreased the longevity of that insect. Acholeplasma laidlawii and A. granularum also multiplied in both leafhoppers.     

广西优质茶树花品种筛选及加工工艺初探

[目的]筛选适制优质茶树花干花的茶树品种并研究其加工工艺,以期为茶树花资源的开发与利用提供参考依据.[方法]通过对茶树花干花感观品质进行评定,筛选出适制优质茶树花干花的茶树品种;并考察不同干燥温度和萎凋时间对茶树花干花品质及其主要化学成分的影响,确定优质茶树花干花加工工艺参数.[结果]广西主要栽培的茶树中适制优质茶树花干花的品种有：六堡茶、台茶12号、八仙茶、福云6号、南山白毛茶、桂平西山茶、凤庆大叶茶、凌云白毛茶和龙胜龙脊茶等9个茶树品种.其中,六堡茶、南山白毛茶、台茶12号可加工成花蜜香型干花;龙胜龙脊茶、八仙茶可加工成高花香型干花;凌云白毛茶可加工成清高优雅型干花;福云6号、桂平西山茶、凤庆大叶茶可加工成花香型干花.在自然萎凋6.0 h、微波杀青后90℃干燥2.0 h的条件下,茶树花干花品质最佳.[结论]不同茶树品种的茶树花品质差异较大,可根据不同品质加工成不同风格的茶树花干花.干燥温度和萎凋时间是影响茶树花加工品质的关键因素,应作为茶树花实际加工的首选参数.     

Paleoindians in beringia: evidence from arctic alaska

Excavations at the Mesa site in arctic Alaska provide evidence for a Paleoindian occupation of Beringia, the region adjacent to the Bering Strait. Eleven carbon-14 dates on hearths associated with Paleoindian projectile points place humans at the site between 9,730 and 11,660 radiocarbon years before present (years B.P.). The presence of Paleoindians in Beringia at these times challenges the notion that Paleoindian cultures arose exclusively in mid-continental North America. The age span of Paleoindians at the Mesa site overlaps with dates from two other cultural complexes in interior Alaska. A hiatus in the record of human occupation occurs between 10,300 and 11,000 years B.P. Late Glacial climatic fluctuations may have made northern Alaska temporarily unfavorable for humans and spurred their southward dispersal.     

Glaciers and nutrients in arctic seas

Significantly higher concentrations of nitrate and silicate were found in glaciated South Cape Fiord than in unglaciated Grise Fiord, in the Canadian Arctic, or in adjacent Jones Sound. No significant differences in phosphate concentrations were found. Glacial activity apparently enriches the concentrations of those nutrients most critically limiting for arctic phytoplankton requirements.     

花卉室内水培技术研究

绿萝用80 mg/kg NAA处理可显著提高生根率和根长.营养液以华南叶菜类a配方对绿萝、马蹄莲、海芋的生长效果最好.     

日光温室越冬茬黄瓜播期对雌花数量的影响

试验研究了日光温室越冬茬黄瓜播期对雌花数量的影响，结果表明，从9月17日-10月6日分期播种，播种时间越晚，前l-12节平均单节雌花数越多，13-20节差异不明显。日光温室栽培黄瓜，周期性座果现象依然十分明显。     

Oil and ice in the arctic ocean: possible large-scale interactions

The diffusion and transport mechanisms generated by the pack ice dynamics of the Beaufort Sea, combined with the slow rate of biodegradation of oil under Arctic conditions, would combine to diffuse an oil spill over the sea and eventually deposit the oil on the ice surface, where it would lower the natural albedo over a large area.     

现代渔业温室中高档盆花立体栽培技术研究

针对本地区气候特点和能源状况,以南京现代渔业科技园温室为例,探讨在渔业温室中冬春季生产蝴蝶兰、一品红、石斛兰等中高档盆花的可能性,以提高现代化温室设施的综合利用效力,提高能源利用率,降低花卉生产单位能源投资成本,提高总体经济效益。