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1.
在成体的许多组织中发现了多能干细胞,这些干细胞可以进行自我复制,参与组织的正常修复。神经干细胞在体外能分化为神经元、星形胶质细胞和少突胶质细胞,并具有多向分化潜能。成体神经干细胞和胚胎干细胞都能分化成成体神经系统中的各种神经细胞。神经干细胞具有自我更新能力,因此神经干细胞可以应用于神经损伤或者神经疾病的修复。本文概述了神经干细胞体外分离培养的方法及其生长影响因子。  相似文献   
2.
本文通过实地调查和异地栽培试验研究了蛇床的生物学特性及资源分布,为蛇床子药材的生产、收购提供了科学依据。  相似文献   
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Bloodstream forms of Trypanosoma brucei that were infective for mammals, when grown in vitro at 37 C for 29 days or 25 months had amounts of variant surface glycoprotein similar to the amounts from bloodstream forms isolated from infected rat blood. The amounts were measured by competition radioimmunoassays for both unique and cross-reacting determinants and the results were the same, providing evidence that a single type of variant surface glycoprotein was measured. Neither radioimmunoassay detected determinants of variant surface glycoproteins in trypanosomes transformed by culturing at 27 C to insect forms not infective for mammals.  相似文献   
5.
随着传统义利观在中国传统文化中的不断丰富和发展,深深地影响着人们的价值观,并在人们的心中形成一种道德自律和民族自觉,对人们的行为发挥着重要的指导作用。在对医学生的培养教育中,往往只注重科学教育,缺乏包括义利观教育等在内的人文教育成为医学生培养系统亟待解决的问题。作为医学院校应当明确当代医患矛盾频出的关键所在,强调医学生建立"重义轻利"的人文理念,不断提高医疗服务道德水平。  相似文献   
6.
香根草栽培平菇的研究   总被引:1,自引:0,他引:1  
本文以香根草为主要配方材料,以常规木屑为对照,设计了12个配方,栽培平菇,通过菌丝的长势和生长速度的不同,筛选适宜平菇生长的配方.研究结果表明,最适配方为香根草48%,类芦20%,芒萁10%,麸皮20%,碳酸钙1%和石灰1%;该配方菌丝长势旺盛、生长速度快,利用该配方栽培平菇,其生物转化率达到102.7%.  相似文献   
7.
Carex nigra plants forming elevated dense tussocks are often named C. nigra subsp. juncella, as opposed to rhizomatous C. nigra subsp. nigra. It is uncertain, however, whether the cespitose growth form is a hereditary trait useful for definition of the distinct taxon or a site modification of little taxonomic value. We used vegetation analyses (phytosociological relevés) to reveal main patterns in ecological demands of the cespitose C. nigra plants in the Czech Republic, and three cultivation experiments to assess changes in clonal growth of C. nigra under various environmental conditions. In the field the cespitose C. nigra plants were typically found in abandoned wet meadows near open water, whereas the rhizomatous morphotypes frequently occurred also in regularly mown wet meadows and in peat bogs. The cespitose growth form disappeared in the cultivations, and the rhizome system responded plastically to immediate environmental stimuli. Number of rhizome branches and mean rhizome length decreased after defoliation of aboveground parts and denudation of belowground parts, whereas increased due to inundation. In the population from a cold site in high altitude (Modrava, Šumava Mts.), however, the originally cespitose plants repeatedly produced shorter and less numerous rhizome branches than the rhizomatous plants cultivated in the same conditions. This suggests ecotypic (genetic) differentiation in some populations of C. nigra, driven by environmental selection for more compact growth form in climatically severe sites. The cespitose C. nigra plants thus arise polytopically, by different mechanisms. The growth form itself therefore cannot serve as the character reliably delimiting C. nigra subsp. juncella as the distinct taxon.  相似文献   
8.
单性木兰种子雨与天然更新的初步调查   总被引:5,自引:0,他引:5  
以位于广西木论国家级自然保护区内的单性木兰为对象,调查了其种子的天然散播和天然萌发、幼苗幼树的生长情况及鼠类对种子的取食危害情况。结果表明:单性木兰种子具休眠特性,种子到达地面后并不立即萌发,至次年4月初—4月中旬才见子叶出土;鼠类对单性木兰种子的取食具有长期性,从种子散播初期至种子萌发的这段时间鼠类均对其种子进行取食(包括地表和土壤中的种子);利用铁丝网罩进行种子萌发的对比实验发现,即使是在无鼠类危害的情况下,单性木兰的种子萌发率也很低;单性木兰天然更新过程中由种子转化成幼苗这个阶段还存在着严重的障碍,低的种子萌发率难以满足单性木兰种群的正常更新。  相似文献   
9.
Cultivation of non-wood forest products (NWFP), although a veritable means of ecosystem and biodiversity conservation and improved natural resource management, has not been sustained in southern Nigeria (Nigeria’s major forest region) notwithstanding the unprecedented rate of depletion of the resource in the wild. For example, efforts in the past to support cultivation of NWFP in southern Nigeria under a USAID funded Cross River State forestry project, especially through nursery establishment for some rural communities, was not sustained as the initiative was abandoned by the participants. Hence to promote cultivation of NWFP, this study ascertained socioeconomic factors that influence cultivation of NWFPs. Multi stage sampling technique was used in selection of respondents (households) from two States: Cross River and Enugu States of southern Nigeria. A sample size of 400 households was used for the study. Probit and multinomial logistic regressions were used in estimating NWFP cultivation. The findings show that cultivation of NWFP was positively determined by gender, farming occupation (especially of women farmers) distance to forests where NWFP was collected, proportion of household food from NWFP, and medium wealth category. Age had a negative effect on cultivation until the age of 46 after which the effect became positive. In addition, household size, gender and farming occupation of household heads positively influenced cultivation of NWFP in plantations as against home gardens while gender and farming occupation had positive effect on cultivation of some stands of NWFP as against home gardens. Incorporating the findings of this study in future intervention project for NWFP cultivation will help sustain the initiative.  相似文献   
10.
不同栽培方式对籼、粳稻根表铁膜和根铁、镉含量的影响   总被引:7,自引:1,他引:6  
在Cd污染土壤中研究淹水、覆膜、覆草和湿润栽培对籼、梗稻不同生育时期根表铁膜Fe、Cd含量和根Cd含量的影响.结果表明,在分蘖期,梗稻根表铁膜Fe含量和根Cd含量在4种栽培方式中平均为6.37和25.49mg.kg-1。分别比籼稻的4.52和16.37mg·kg-1增加1.85和9.12mg·kg-1.在孕穗期,粳稻根表铁膜Fe、Cd含量和根Cd含量在4种栽培方式中平均为1.60、16.35和54.68mg·kg-1,分别比籼稻的1.06、9.56kg和43.31mg·kg-1增加0.54、6.79和11.37mg·kg-1.在灌浆期,梗稻根表铁膜Fe含量覆草和湿润栽培为0.89和1.00mg·kg-1,分别比籼稻的0.63和0.30mg·kg-1增加0.26和0.70mg·kg-1;梗稻根表铁膜Cd和根Cd含量在4种栽培方式中平均为15.23和73.68mg·kg-1,分别比籼稻的3.46和52.38mg·kg-1增加11.77和21.30mg·kg-1收获时。根表铁膜Fe含量淹水栽培的籼稻为1.21mg·g-1,比梗稻的0.65mg·g-1增加0.56mg·g-1,覆草栽培的梗稻为0.94mg·g-1,比籼稻0.55mg·g-1增加0.39mg·g-1;根表铁膜Cd含量湿润栽培的梗稻为7.96mg·kg-1,比籼稻的5.09mg·kg-1增加2.87mg·kg-1;根Cd含量梗稻在4种栽培方式中平均为54.53mg·kg-1,比籼稻的35.91mg·kg-1增加18.62mg·kg-1。  相似文献   
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