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121.
运用计量学的方法,对《重庆图情研究》2004~2008年间载文、作者及引文情况进行统计分析。通过对作者区域、所属系统及合著率、合作度进行细化分析,以期把握该刊发展状况,对学科和刊物的发展方向提出一些思考。  相似文献   
122.
为保证草坪绿化质量 ,延长其寿命 ,结合近年来在公路草坪施工与养护管理中积累的实践经验 ,对公路草坪的种类、生长习性 ,以及草坪建植后的浇水、除杂草、修剪、施肥、病虫害防治等养护管理技术进行了探讨与总结 ,以期为各地公路草坪绿化建设提供借鉴与参考。  相似文献   
123.
Summary Components of partial resistance, infection frequency and latency period, were determined in 71 winter and spring wheat genotypes in the seedling stage, after infection with three races of leaf rust (Felix 3B, Clement B and Betuwe 85C) at three different day/night temperature regimes (24/18°C, 18/12°C and 12/6°C). The genotypes were split into two groups and two separate experiments were carried out. Five genotypes, SVP 84039, Akabozu, Banco, BH 1146 and Orso, conferred a low infection frequency and a long latency period and Westphal 12A a long latency period, indicating a relatively high level of partial resistance. The correlation coefficient between infection frequency and latency period was low. Race-specificity was not found. There was a significant temperature effect on the latency period. In the second experiment the temperature x genotype interaction was significant. Temperature-response functions of transformed data demonstrated that the latency periods of four relatively resistant genotypes, Westphal 12A, Banco, BH 1146 and Orso and of Sarno and Mirela were most sensitive to temperature. The range between the genotypes with the longest and the shortest latency period was highest at 12°C. Therefore, low temperature regimes are preferred to distinguish differences in level of partial resistance.  相似文献   
124.
现有生物质能转换利用技术综合评价   总被引:1,自引:0,他引:1  
本文介绍了生物质能转换利用的方法,对现有生物质能转换技术进行了比较,运用层次分析法从技术先进性、经济可行性和环境安全性三个方面对现有生物质能转换利用技术进行了综合评价,提出了生物质能转换利用技术的优先发展顺序和发展方向,为我国生物质能转换利用技术的发展和应用提供参考依据.  相似文献   
125.
The effects of crown pruning of mature indigenous fruit trees of Vitellaria paradoxa C. F Gaertn (commonly known as karité) and Parkia biglobosa (Jacq.) R. Br. ex G. Don (commonly known as néré) on recovery of crown size and fruit yield were assessed during 6 years in an agroforestry parkland system in Burkina Faso. Three treatments of crown pruning (total-pruning, half-pruning and a control of no-pruning) were applied to karité and néré. Each treatment comprised ten individuals of each species or a total of 60 trees of both species. Six years after pruning, higher recovery (81%) of crown diameter was achieved in total-pruned trees of néré as opposed to karité which recovered by only 73%. On the contrary, fruit production in total-pruned trees of karité recovered by 83% 5 years after pruning and fully (100%) 6 years after pruning as opposed to néré which recovered by only 57% 5 years after pruning but declined to 16% on the sixth year probably due to interannual variability. Fruit yields did not differ significantly between unpruned and half-pruned trees of both species throughout the experiment period. Total pruning may, therefore, be recommended to farmers to rejuvenate old trees of karité in parklands on the basis of fast recovery of fruit and slow recovery of crown in the species. Slow recovery of crown in pruned trees is the most desirable characteristic in parklands in order to avoid the negative effect of tree shade on adjacent crop.  相似文献   
126.
大气氮沉降的不断加剧,改变了土壤理化性质,直接影响植物的生长与发育,间接影响了陆地生态系统碳库,进而可能改变全球气候变化进程。森林是陆地生态系统的主体,因此,弄清氮沉降如何影响森林生态系统碳库,对预测全球气候变化具有重要意义。笔者旨在详细分析氮沉降对森林生态系统土壤碳库输入和输出的影响,阐述氮沉降对森林生态系统凋落物分解、细根周转和土壤呼吸的影响研究进展和作用机制。截至目前,关于氮沉降对于陆地生态系统的影响研究报道较多,且国内外诸多学者也在森林生态系统土壤碳库对氮沉降的响应领域开展了较多试验研究,但多集中于碳输入和输出的总量分析,而对输入和输出各个组分的研究相对较少。笔者综述了国内外有关森林生态系统碳库输入和输出各组分对氮沉降响应的相关研究,为进一步揭示其响应机制和途径提供参考依据。  相似文献   
127.
目的 研究棉花收获前植保无人飞机喷施脱叶催熟剂的效果。方法 使用植保无人飞机以22.5 L·hm-2的施药液量喷施采收前30 d的棉花‘金棉18#’、‘北泉9#’、‘植金13#’和‘合信47#’,以人工机械喷雾(施药液量450 L·hm-2)为对照,测试4种棉花冠层中的雾滴覆盖率;于药后4、7、14和21 d分别进行脱叶和吐絮效果调查,计算不同棉花品种的脱叶率和吐絮率;检测4种棉花的纤维品质和产量构成因子(铃质量、衣分)。结果 雾滴覆盖率在4种棉花品种中均呈现出上部冠层显著高于中下部冠层的规律,且植株越高,中下部冠层的雾滴覆盖率越低;除‘合信47#’人工喷雾处理的吐絮率没有达到机采棉采收标准外,其余处理的脱叶率和吐絮率均达到了机采棉的采收标准;4种棉花品种的纤维品质和产量构成因子(铃质量、衣分)均不受施药器械的影响。结论 植保无人飞机可作为棉花采收前喷施脱叶催熟剂的施药器械。  相似文献   
128.
Summary Forty strains of mungbeans, including all of the entries in the 1st and 2nd International Mungbean Nurseries (IMN), were grown in plant growth chambers in photoperiods of 12, 13, 14, 15, and 16 hours and mean temperatures of 18, 23, and 28°C. Results show that (1) mungbean strains differ in their flowering response to photoperiod and to mean temperature; (2) increasing the photoperiod of reducing the mean temperature delayed flowering, the amount of delay varied with the strain: (3) variations in mean temperature may alter the effect of the photoperiod on flowering in particular strains. Twenty-five strains which flowered in all photoperiod-temperature treatments could be divided into four groups, each group being successively later in flowering. The remaining 15 strains could be divided into four groups, according to their failure to flower within 105 days in specific photoperiod-temperature treatments. Flowering response in the growth chamber is useful in explaining flowering response in the 2nd IMN at three locations varying from 14°N to 49°N latitude.Contribution No 7516 from the Missouri Agricultural Experiment Station.  相似文献   
129.
Large mounds amended with plant residues are a common cultivation method for sweetpotato (Ipomoea batatas) in the western parts of the Papua New Guinea highlands, with a suggested benefit of elevated root zone temperature (RZT) from decomposition. This study aimed to evaluate whether RZT affects the formation and growth of sweetpotato storage roots. Experiments evaluated the effects of a constant elevated RZT on the Beauregard cultivar and of a short‐term increase in RZT on the Beauregard and Northern Star cultivars. Plants were grown in 18‐L pots divided into a control compartment (constant RZT at 20°C) and a treated compartment (RZT at 30, 40 or 50°C). Constant elevated RZT was maintained until harvest, while short‐term increase in RZT occurred in weeks 2 and 3 only. Constant elevated RZT did not affect the total number of storage roots, but RZT of 30°C and above reduced the dry‐biomass of storage roots. The short‐term increase in RZT did not alter the total number or dry‐biomass of storage roots in Beauregard, while both of these attributes were reduced at RZT of 40°C or above in Northern Star. Elevated RZT inhibited dry‐biomass accumulation of storage root, with a more pronounced impact at constant elevated RZT. These results demonstrate that any benefits of the mound culture on sweetpotato yield production do not arise through the influence of temperature elevation.  相似文献   
130.
为了明确ABA对孕穗期低温下水稻结实率及叶片生理特性的调控效应,本试验在盆栽条件下,以2个水稻(Oryza sativa L.)品种‘龙粳11’(冷敏型)和‘龙稻5’(耐冷型)为材料,于孕穗期在人工气候室进行低温(15℃,持续1,2,3,4,5天)处理,并喷施不同浓度的脱落酸(ABA),研究低温条件下ABA对不同水稻结实率的调控效应,同时探讨了ABA和低温对水稻叶片膜透性、抗氧化酶等生理特性的影响。结果表明:低温条件下,‘龙稻5’的结实率变化不大,‘龙粳11’的结实率显著降低,20 mg/L的ABA能够有效缓解低温伤害,相对提高低温胁迫下水稻的结实率。叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性表现出先升高后下降的变化趋势,‘龙稻5’的抗氧化酶活性、可溶性糖和可溶性蛋白含量高于‘龙粳11’,但丙二醛(MDA)含量和相对电导率低于‘龙粳11’。ABA可提高冷敏品种的抗氧化酶活性、可溶性糖和可溶性蛋白的含量,同时可降低MDA含量和相对电导率。这说明ABA可以通过调控水稻抗氧化酶、可溶性糖等生理指标的活性及含量,进而提高冷敏水稻品种的耐冷性。  相似文献   
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