共查询到19条相似文献，搜索用时 563 毫秒
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用ODO冷冻断裂法观察人膈腹膜间皮细胞和毛细血管的超微结构 总被引：1，自引：0，他引：1
ONO冷冻断裂法是一项新的扫描电镜制样技术。利用这项技术,将样品在-196℃下冷冻,然后把样品掰裂。用扫描电镜观察样品断裂面细胞的内部结构,具有较高的分辨率。并能显示细胞内部细胞器之间的关系。其缺陷是欲观察的断裂面不能预先确定,而是随机的。作者应用ODO冷冻断裂法,对人膈腹膜间皮细胞和毛细血管进行了观察. 相似文献
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借助ODO冷冻断裂扫描电镜制样技术,对人胎膈肌细胞进行研究,获得人体横纹肌细胞、肌原纤维、肌节以及暗带(A带)、明带(I带)和H带的扫描电镜资料。 相似文献
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半日花体细胞胚胎发生过程中超氧物歧化酶(SOD)活性的变化 总被引：2，自引：0，他引：2
采用萌发几天的半日花 (Helianthemum,songoricum)为外植体 ,以 MS为基本培养基 ,附加不同激素浓度 ,诱导子叶和胚根形成愈伤组织。选生长良好的愈伤组织转入分化培养基中诱导胚状体发生。通过对胚状体发生过程的观察 ,进行 SOD酶活力的测定 ,得出生长旺盛的愈伤组织、体细胞胚等SOD活力变化不同 ,并存在一定的相关性 相似文献
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大麦幼胚的超低温保存 总被引：1，自引：0，他引：1
大麦(Hordeum vulgare L.)幼胚经二甲亚砜(DMSO)和山梨醇复合保护处理,可以在液氮(-196℃)超低温保存.山梨醇预培养2天可以明显提高两步冷冻法冻存幼胚的存活率.4℃预处理4小时对胚存活率的影响不大,但它使幼胚分化能力下降,超低温冷冻对盾片的伤害小于对胚轴的伤害.快速冷冻法冷冻大麦幼胚取得良好的保存效果,冻存后的幼胚经过恢复培养,长出绿苗. 相似文献
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本实验首先在MS基本培养基上培养盐地碱蓬(SuaedaSalsa(L.)Pall.)的无菌苗,然后用上述无菌苗茎段为外植体在MS1培养基上诱导培养,初始愈伤组织为深黄色、非松脆型,愈伤组织诱导频率为95.64%以上.在继代培养基MS2上继代数月后得到了生长旺盛、疏松、呈乳白色的愈伤组织,用不同组成浓度的酶解液酶解松散型愈伤组织,进一步分离、提纯制备出具有活力的原生质体.以愈伤组织为材料制备原生质体的最适酶解液浓度为10g/L纤维素酶 5g/L离析酶 0.6mol/L甘露醇 0.05mol/L CaCl2.2H2O 0.1%MES.最适酶解时间为12-16h. 相似文献
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竹类果实与淀粉形态及系统位置 总被引：1，自引：0，他引：1
本文收集了竹类5个族21属30种的竹类果实，作了外部形态与淀粉形态的研究，从而为确立
各竹属的系统分类位置提供了科学依据，进一步证实了浆果类果实不具有胚乳，从而认为Oreocalamus
(Keng，1940)，Qiongzhuea(薛纪如等，1979)，Ferrocalamus(耿伯介等，1982)与Chimonobambusa
Subg．Chimonobambusa系统位置更接近于Melocanneae(Keng，1940)。 竹类果实淀粉均为复粒结构。果实大小、淀粉粒大小与淀粉小粒相互之间有一定的联系。 相似文献
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短柄五加Eleutherococcus brachypus Harms种子为扁肾形,种皮由一层细胞构成。种子脱落时,胚
为心形胚期,胚周围的胚乳细胞解体形成液样囊腔,并包裹胚,胚细胞中存在较多蛋白质,胚乳细胞贮
存大量蛋白质颗粒和脂类,但两者均未见多糖颗粒。有萌发潜能的种子只占全部种子的9.27％。在试
验地种植条件下饱满种子经18～19个月后萌发,出苗率为1．67％,该过程细胞化学特点是胚细胞中蛋
白质含量逐渐减少,并逐渐积累少量多糖颗粒。种子经变温层积处理6个月即可完成后熟过程,其细胞
化学特点是胚细胞中蛋白质含量逐渐减少,但在心形胚后期即已积累大量多糖颗粒,并一直保持至胚
完全发育成熟。经比较短柄五加与刺五加的种子结构、后熟作用及其细胞化学特点,认为短柄五加种子质量差、自然状态下后熟时间长和出苗率低是短柄五加致濒的重要生殖因素,并提出了相应保护方法。 相似文献
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Shanmugasundaram Kumaravel 《Indian journal of clinical biochemistry : IJCB》2012,27(4):422-425
Criterion for patient selection and demographic comparison between the two groups, the numbers in individual groups (normal union or defective union) how the observers were blinded for the samples and control group measurements in the graphs were not mentioned. No data on actual measurement levels is given. No where it is mentioned like it is an average of all normal union or defective union in tables or diagrams. The treatment methodology maybe still focused including either conservative or surgical treatment since a displaced fracture cannot be compared with an osteotomy. The cases shall be followed up for a longer period. Some suggestions on how to blind the observers is given. In the one year period there was neither mention of the failure of treatment or complications of any of neither these 36 cases nor any drop out for follow-ups. There was also no mention of any case which initially put on conservation was changed to surgical management. The authors could have one group of patients taking this food stuff and another group who refused this food stuff. The statistical test used to compare the levels of factor is not mentioned. Mere statement that ‘p’ values were significant will not benefit the reader. Failure to produce X-rays even for a single case weakens the study. X-rays are needed to confirm the diagnosis of a fracture and confirm the position of implants and fracture fragments. The remaining period after confirming the fracture/implant position the case shall be followed only with marker estimation. Once the desired levels of increase or tapering of marker level achieved then X-rays can be taken to correlate with clinical findings and radiology. Union as one group and the second group shall be called as non-union or delayed union. The second group (the poor callus group) is mentioned as malunion possibly by over-sight. Probably they were meaning the non union or delayed union group or defective union as malunion. This should be preferably be written non union or delayed union. Malunion means the fracture actually unites and union process is completed. In a group of fractures (hypertrophic non unions) the callus formation is excessive, still the fracture is ununited. Thus the enzyme or markers alone cannot disclose the details of the completion of union they can herald bone formation. 相似文献
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Mukhopadhyay M Sinha R Pal M Bhattacharyya S Dan A Roy MM 《Indian journal of clinical biochemistry : IJCB》2011,26(3):274-278
The progress of fracture union requires close monitoring. Whereas, clinical examination and radiographic studies assess the
outcome, biochemical markers like serum alkaline phosphatase and urinary hydroxyproline reflect the actual status of bone
resorption and bone formation over a short time frame. 36 patients of long bone fracture were randomly allocated for the study.
When the patient reported to the Department of Orthopedics after fracture, serum and urinary samples were collected and X-ray
of the affected part were taken. Subsequent samples were collected and X-ray taken just after management (either operative
or conservative), after 3rd, 5th, 8th and 12th week, respectively after onset of fracture. According to the course of callus
formation the patients were divided into two groups that progressed to proper union or malunion. The levels of serum alkaline
phosphatase, urinary total and free hydroxyproline levels were measured and statistically analysed and compared. A statistically
significant positive correlation between total urinary hydroxyproline excretion and serum alkaline phosphatase indicate progress
towards satisfactory union. Thus, serial monitoring of biochemical markers of bone turnover can be used as an adjunct to clinical
and radiological evidence of fracture healing. 相似文献
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粮食进出口贸易结构影响国家粮食安全。在开放的全球粮食贸易系统中,贸易格局与贸易安全水平息息相关,因此,准确评判中国粮食贸易结构的安全程度成为亟待解决的重要问题。本文采用净贸易量计算法、香农熵指数法对中国1987—2016年主要粮食（玉米、小麦、稻米、大豆）的进出口贸易时空格局和贸易结构安全性进行了分析。研究发现：①2008年之前,小麦、大豆以进口为主,玉米、稻米以出口为主,2007—2008年世界粮食危机后皆表现为入超特征。②小麦主要进口国（美、加、澳）较为稳定,大豆、玉米、稻米主要进口国变化较大。③粮食进出口结构安全水平存在差异,总体贸易结构安全程度得到提高。④“反向抑制区”国家粮食进出口比例与其香农熵值成反比,“协同增长区”国家粮食进出口比例与其香农熵值成正比,粮食贸易伙伴进出口比例与其对本国贸易结构稳定性的贡献度呈非线性关系。本文揭示了1987—2016年间中国4种粮食对外贸易的时空格局变化,分析了粮食贸易结构演变的动态特征,丰富了对中国粮食贸易的实证研究。 相似文献
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添加剂和激素对印楝脱分化及印楝素含量的影响 总被引：4，自引：0，他引：4
不同添加剂和激素配比对印楝愈伤组织生长及其印楝素生物合成有较大影响：蔗糖有利于细胞生长,葡萄糖有利于印楝素积累;肌醇对印楝愈伤组织生长和印楝素合成有促进作用;各种添加剂对印楝愈伤组织生长有促进作用,椰子乳对印楝素合成有利;综合考虑印楝愈伤组织生长,兼顾印楝素含量,较适宜的组合为２,４－Ｄ２．０＋６－ＢＡ０．５ 相似文献