毛榛与平欧杂交榛的花粉制备技术的研究     

龙作义  赵鹏飞  逄宏扬  李雪  李红莉  杨燕超 《林业勘查设计》2010,(1)

毛榛(Corylus mandshurica Maxim.)是东北地区的主要经济林树种,它具有抗寒能力强,树体高,坚果品质优良等优点,用其作为亲本与平欧杂交榛(Corylus heterophylla×C.avellana)进行杂交育种,首先得解决毛榛与平欧杂交榛的花粉制备问题。经过多年的的研究,该项技术被成功解决了,为杂交育种提供了技术上的保证。  相似文献   

短轮伐期巨尾桉人工林主伐年龄模型研究     

何龙  吕勇  张震  边更战 《四川林勘设计》2010,(4)

短轮伐期巨尾桉人工林合理主伐年龄的确定一直存在争议。在充分分析影响巨尾桉人工林主伐年龄的各种成熟理论的基础上,构建了短轮期巨尾桉人工林的主伐年龄模型,通过此模型可以比较科学地确定巨尾桉人工林的主伐年龄,为巨尾桉人工林的科学经营提供技术支撑。通过此模型分析得出广东美林生态农业有限公司巨尾桉人工林主伐年龄为5.71年。  相似文献   

A report of 7 cases of feline vulval adenocarcinoma     

Welsh JB  Best SJ  Yager JA  Foster RA 《The Canadian veterinary journal. La revue veterinaire canadienne》2010,51(7):764-766

Seven cases of feline vulval adenocarcinoma are reported. Follow-up information was available for 5 cats, and all but 1 of these was euthanized within 2-18 mo of diagnosis (median 9.2 mo) for reoccurrence of local disease (3 cases) and/or clinical signs consistent with metastases (3 cases). There was no relationship between histological features of the tumor and outcome.  相似文献   

New genes in Drosophila quickly become essential     

Chen S  Zhang YE  Long M 《Science (New York, N.Y.)》2010,330(6011):1682-1685

To investigate the origin and evolution of essential genes, we identified and phenotyped 195 young protein-coding genes, which originated 3 to 35 million years ago in Drosophila. Knocking down expression with RNA interference showed that 30% of newly arisen genes are essential for viability. The proportion of genes that are essential is similar in every evolutionary age group that we examined. Under constitutive silencing of these young essential genes, lethality was high in the pupal stage and also found in the larval stages. Lethality was attributed to diverse cellular and developmental defects, such as organ formation and patterning defects. These data suggest that new genes frequently and rapidly evolve essential functions and participate in development.  相似文献   

Effects of Chloroformic Extracts from Washed and Unwashed Papaya Seeds (Carica papaya) on the Sperm Concentration of Dogs     

A Ortega‐Pacheco  M Jiménez‐Coello  E Gutiérrez‐Blanco  KY Acosta‐Viana  E Guzmán‐Marín  MA Zavala‐Sánchez  NE Montalvo‐Beltrán  MS Pérez‐Gutiérrez 《Reproduction in domestic animals》2010,45(6):1126-1129

Papaya seeds (Carica papaya Linn) have been found to have a significant effect on sperm characteristics in some mammals, including humans, but no studies have investigated the effects on dogs. In the present study, a significant decrease in sperm concentration was observed in a group of dogs treated with extracts from washed papaya seeds, but no decrease was observed in the group of dogs treated with non‐washed seeds. An important effect of extract components from washed seeds such as fatty acids is probably involved in the reduction of sperm production because of Sertoli cell damage, as has been suggested for langur monkeys. Dilution of the active components in the non‐washed papaya seeds or interference with some of the components may reduce the expected effect on spermatogenesis. This first report on the effects of a chloroformic extract of papaya seeds in dogs suggests that an increased dose is necessary to achieve azoospermia.  相似文献   

Evaluation of Feral Swine-Specific Feeder Systems     

David B. Long  Tyler A. Campbell  Giovanna Massei 《Herpetological Monographs》2010,32(2):8-13

  相似文献   

枣MAPK基因片段克隆与分析   总被引：1，自引：0，他引：1  

赵彦檩  彭龙  赵锦  刘孟军 《河北农业大学学报》2010,33(6)

采用同源基因克隆法,首次获得了枣MAPK基因片段543 bp,经Blast比对,该序列与湖北海棠(Malus hupehensis EF427897.1)、蓖麻(Ricinus communis XM002509805.1)、西府海棠(Malus micromalus AF435805.2)和欧洲山毛榉(Fagus sylvatica AJ784997.1)的相似率分别为86%、86%、85%和84%。进一步进行系统进化分析,证明该基因属于MAPK中TEY型的B类。  相似文献   

农牧交错带不同土地利用方式对土壤质量的影响          下载免费PDF全文

郭彦军  倪郁  韩建国  韩龙  郭芸江  唐华 《西南大学学报(自然科学版)》2010,32(1)

在我国北方农牧交错带,研究了不同土地利用方式对土壤质量的影响.结果表明,天然草地和过牧草地土壤全氮、总有机碳和全磷含量整体高于耕地和林间草地,退耕地种草后土壤全氮、总有机碳含量增加,全磷含量无显著变化.耕地和过牧草地土壤速效磷含量高于其他土地利用方式.天然草地、过牧草地和耕地土壤pH值显著高于林间草地和人工草地,而土壤电导率均为过牧草地显著高于天然草地,天然草地显著高于林间草地、人工草地和耕地.林间草地和过牧草地土壤容重显著高于天然草地和耕地,而天然草地土壤含水量显著高于其它土地利用方式,林间草地土壤含水量最低.  相似文献   

以Dirac测度为源的拟线性退化抛物方程解的唯一性     

李龙  詹华税 《厦门水产学院学报》2010,(3):234-236

研究了以Dirac测度为源的拟线性退化抛物方程ut-Δum=δ（x）,（x,t）∈Q的Cauchy问题解的唯一性,其中δ（x）是Dirac测度,m〉1,Q=RN×（0,＋∞）.  相似文献   

基于正交试验和神经网络的烤烟栽培技术优化   总被引：1，自引：0，他引：1  

宫长荣  张玺  张学伟  张勇刚  程龙  景延秋 《江西农业学报》2010,22(1):14-16

应用正交设计方法,研究烤烟主要栽培因子有机肥比例、种植密度、留叶数与烟叶品质的关系,利用BP神经网络建立了烤烟在豫中地区土壤中等肥力条件下的高产优质栽培模型,最后得出以优质烟内在质量为目标函数的最佳栽培方案,即:有机肥比例25%,种植密度16500株/hm2,留叶数为22片/株。  相似文献