自动分布阈值图像多目标分割算法     

罗三定  张中良 《湖南农业大学学报(自然科学版)》2008,35(2):77-80

提出了一种有实际背景的最小费用箱子覆盖问题──每个物品有长度和费用2个参数.针对局外最小费用箱子覆盖问题,给出了一个求解该问题的最坏情况渐近性能比为1/2算法C-FF1.同时给出了一个求解该问题的局内算法C-FF2,其绝对性能比为1/2,并证明了不存在绝对性能比大于1的算法.  相似文献   

膨大素处理对葡萄果实性状的影响   总被引：3，自引：0，他引：3  

于万春  高庆玉  戴正 《黑龙江农业科学》2008,(6)

以京亚和京秀两个葡萄品种为试材,以膨大素处理葡萄果实,结果表明:以花后15 d、浓度10 mg·kg-1的效果为最好.京亚和京秀两个品种座果率增加16.8%和10.3%;单果质量增加36.7%和28.7%;穗重增加47.9%和25.7%;果形指数减少0.036和0.048.果实中可溶性糖、有机酸和维生素C含量略有下降,增加果实的糖酸比.果实前期赤霉素含量增加,增加了果实的座果率;脱落酸含量的提高促进了代谢库细胞对同化物的吸收.  相似文献   

两种常温固化木材胶粘剂胶接强度分析     

岳孔  卢晓宁  黄河浪  那斌 《林业科技开发》2007,21(2):54-57

对两种木材用常温固化胶粘剂--单宁-甲醛胶粘剂和聚氨酯胶粘剂胶接的速生杨木的静态剪切强度进行了测试与分析.研究结果表明,以速生杨I-72为被胶接对象,自制的双组分型单宁胶压缩剪切强度范围为8.08～8.92MPa,但木破率较低,要满足日本集成材JAS标准中用胶规定,需进一步研究改进.相比较而言,聚氨酯胶粘剂的胶接强度较高,其压缩剪切强度值均在9.8MPa以上,木破率在75%以上,能够满足日本集成材JAS标准中用胶的规定.  相似文献   

Introduced slugs and indigenous caterpillars as facilitators of carbon and nutrient mineralisation on a sub-Antarctic island     

V.R. Smith 《Soil biology & biochemistry》2007,39(2):709-713

Indigenous soil macroinvertebrates (moth larvae, weevil larvae, earthworms) are cardinal agents of nutrient release from litter on sub-Antarctic Marion Island (47°S, 38°′E). Their populations are threatened through predation by introduced house mice, which do not prey on an introduced slug Deroceras panormitanum. A microcosm study was carried out to explore whether slugs affect rates of carbon and inorganic nutrient mineralisation from plant litter differently to an indigenous caterpillar (larva of a flightless moth Pringelophaga marioni). Caterpillars stimulated N, Ca, Mg and K mineralisation from plant litter two to five times more than slugs did, whereas the two invertebrate types stimulated C and P mineralisation to the same degree. Consequently, ratios of C:N and N:P released from the litter were different for slugs and caterpillars. Such differences might affect peat nutrient quality and ultimately the peat accumulation-decomposition balance, an important driver of ecological succession. This suggests that slugs cannot simply replace caterpillars without consequences for ecosystem structure and functioning on the island.  相似文献   

安徽农业大学景观环境设计初探     

祝彩虹 《河北农业科学》2008,12(3):120-122

针对安徽农业大学景观环境现状,在深入分析校园景观环境优势与劣势的基础上,结合实际,从塑造环境多样性,创造绿化情趣、改造现有绿化空间,开放绿化场地,提高环境利用率等方面提出了改造建议。  相似文献   

Accumulation of Zinc and Molar Ratio of Phytic Acid and Zinc during Maize Grain Maturation     

M. Horvati&#;  M. Ga&#;&#;  M. Filajdi&#; 《Journal of Agronomy and Crop Science》1998,180(4):233-239

Dynamics of the accumulation of total ash and zinc, and their relationships with total dry matter, crude proteins and phytic acid during maize grain maturation were investigated. The investigation was carried out on normal maize hybrids grown under the same topographical and agrotechnical conditions over two consecutive vegetation years.
The amount of total ash, expressed on fresh and dry matter bases, changed significantly (P = 0.05 and P = 0.01) during grain maturation depending on maturity stage and variety. The dynamics of the accumulation of ash in fresh grain matter during maturation as well as the ash amount in dry matter of mature grains were significantly affected by environmental conditions.
The accumulation of zinc in fresh matter of developing grain was significantly affected (P = 0.05 and P = 0.01) by the degree of grain maturity and by variety, and correlates significantly (P = 0.001) and positively with the deposition of total dry matter, crude proteins as well as with phytic acid in both vegetation years.
The molar ratio of phytic acid and zinc increased significantly during grain maturation indicating a possible decrease of zinc availability.  相似文献   

中国商业银行资本充足性管制有效性的实证分析     

张强  武次冰 《湖南农业大学学报(自然科学版)》2007,34(11)

为了检验资本充足性管制对中国商业银行的资本充足率和风险的影响,在国外学者研究的基础上,构建了一个联立方程模型.根据这个模型,采用两阶段最小二乘法(2SLS),分析了中国银行业从2002~2005年的数据.分析表明:不管是资本充足情况较好的银行,还是资本充足情况不好的银行在资本充足性管制的压力下都提高了资本充足率;资本充足性管制促进了商业银行风险的降低.不过,这个效应正在减弱.  相似文献   

混播比例和刈割期对混播草地产草量及种间竞争的影响   总被引：4，自引：1，他引：3  

锡文林  张仁平 《中国草地学报》2009,31(4)

对新疆石河子绿洲区紫花苜蓿与无芒雀麦混播草地的群落生物量、茎叶比、种间竞争力进行了动态研究.结果表明,以紫花苜蓿7.5kg/hm2、无芒雀麦15kg/hm2的比例混播并在紫花苜蓿初花期刈割为最佳组合,干物质产量为23.4t/hm2.两种牧草种间竞争力和竞争率分析表明,不同的混播比例和刈割期对两种牧草的竞争力有一定影响,紫花苜蓿的竞争力强于无芒雀麦,在竞争中占有优势.  相似文献   

Determining the optimum digestible isoleucine to lysine ratio for Ross 708 x Ross YP male broilers from 0 to 18 d of age     

A.T. Brown  J. Lee  R. Adhikari  K. Haydon  K.G.S. Wamsley 《The Journal of Applied Poultry Research》2022,31(1):100217

  相似文献   

南方三省(区)南洋楹气候区划的研究     

郑永光  梁启英  周小珍 《中南林业科技大学学报(自然科学版)》2004,24(1):6-9

选择纬度、经度以及16个与水热状况有关的气象因子进行R型主成分分析,用前5个主成分坐标值进行模糊ISODATA聚类分析,将研究区划分为3类;用逐步判别分析建立了各类的判别函数式,回判准确率为91.81%;结合模糊相似优先比的结果,将研究区区划为南洋楹适宜发展区、南洋次适宜发展和南洋楹控制发展区3个气候区.  相似文献