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石蜡切片是植物解剖学和病理学观察的重要手段。该方法从取样到切片完成约需一周的时间,操作周期较长。本试验对水稻品种丽江新团黑谷的叶片分别进行了微波石蜡和传统石蜡的切片并用苯胺蓝染色对结果进行比较。在微波石蜡切片中通过对固定、脱水和浸蜡等操作的改进使得该方法只需约3h即可完成切片。微波石蜡切片组织的完整性和染色的效果与传统石蜡切片相近,叶片的表皮、叶肉细胞和维管束等不同叶片结构均可清楚地进行显微观察和拍照。结果显示,可利用微波石蜡方法对水稻叶片进行制片且可较大幅度缩短处理的时间,提高工作效率。 相似文献
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目的观察小鱼眼球(直径在0.3cm左右)视网膜组织石蜡切片的制作方法。方法鲻鱼和罗非鱼各5条,采得眼球20个,用体积分数(下同)95%乙醇85mL 10%中性甲醛10mL 冰醋酸5mL混合而成的FAA固定液进行固定;脱水前先用医用7号针头刺破眼球后再进行脱水、透明、石蜡包埋、切片和HE染色,最后在光镜下观察结果。结果20个眼球的视网膜组织结构和层次均基本保持完整,细胞形态清晰。结论0.3 cm左右直径的鱼类小眼球用FAA固定液固定和针刺破眼球后脱水法制作石蜡切片方法是可行的。 相似文献
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以西瓜雄性不育两用系为材料,利用常规石蜡切片对其雄花芽组织和细胞形态发育过程进行了观察,探讨了西瓜雄性不育的机理.结果表明,不育花药壁组织在发育过程中,没有分化形成正常的内壁、中层及绒毡层,不能为花粉母细胞的发育提供物质、能量和信息的传递,造成花粉母细胞在减数分裂期发生异常,不能形成正常的四分体,因而未能形成正常的花粉粒而导致败育. 相似文献
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Differentiation of embryonic stem cells to insulin-secreting structures similar to pancreatic islets
Lumelsky N Blondel O Laeng P Velasco I Ravin R McKay R 《Science (New York, N.Y.)》2001,292(5520):1389-1394
Although the source of embryonic stem (ES) cells presents ethical concerns, their use may lead to many clinical benefits if differentiated cell types can be derived from them and used to assemble functional organs. In pancreas, insulin is produced and secreted by specialized structures, islets of Langerhans. Diabetes, which affects 16 million people in the United States, results from abnormal function of pancreatic islets. We have generated cells expressing insulin and other pancreatic endocrine hormones from mouse ES cells. The cells self-assemble to form three-dimensional clusters similar in topology to normal pancreatic islets where pancreatic cell types are in close association with neurons. Glucose triggers insulin release from these cell clusters by mechanisms similar to those employed in vivo. When injected into diabetic mice, the insulin-producing cells undergo rapid vascularization and maintain a clustered, islet-like organization. 相似文献
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从新制度经济学的视角,把农民合作组织视为是由一系列的长期契约关系所构成的一个"契约集",把对其组织形式的选择问题转化为对该组织内部契约模式的选择问题;通过交易成本经济学的理论框架,分析不同农民合作组织契约模式的形成机制和决定因素,并对云南蒙自甜石榴产销联合社进行个案分析。结果表明,合作组织对于契约形式的选择是对多种因素综合权衡的结果;新的组织模式或契约安排与原有制度安排存在互补关系;合作组织模式的选择是影响合作效率和组织稳定性的重要因素。一个有效率的组织模式既取决于组织自身的交易特性,又要考虑与外部交易环境的相容性;契约选择的过程要遵循客观的演化规律,但不必拘泥于某一既定形式。 相似文献
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Absence of TGF-beta receptors and growth inhibitory responses in retinoblastoma cells 总被引:22,自引:0,他引:22
A Kimchi X F Wang R A Weinberg S Cheifetz J Massagué 《Science (New York, N.Y.)》1988,240(4849):196-199
The responses of retinoblastoma tumor cells and normal retinal cells to various growth inhibitory factors were examined. Whereas fetal retinal cells were highly sensitive to the antimitogenic effects of transforming growth factor beta 1 (TGF-beta 1), retinoblastoma tumor cell lines were all resistant to this factor. Binding assays and affinity labeling of these cells with radioiodinated TGF-beta 1 revealed that the cells did not have TGF-beta receptors. The retinoblastoma cells lacked the three affinity-labeled proteins of 65, 95, and 300 kilodaltons typically seen in human cell lines and thus differed from normal retinal cells and from other types of neuroectodermal tumors that display the normal pattern of receptors. Loss of TGF-beta receptors, which is a rare event among tumor cells, may represent one mechanism through which these cells escape from negative control and form retinoblastomas. 相似文献
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农村非正式组织的存在形式多样,最具代表型的有宗族组织、宗教组织、农民自发维权组织和新型农村合作经济组织。这些非正式组织的生存能够极大满足农民生产、生活以及精神方面的多种需求,对于农村社会的稳定和农村经济的发展有着重要意义。依据不同非正式组织的特点,通过协调非正式组织与正式组织的关系、取缔非正式组织,规范和正视非正式组织的存在等措施来引导农村非正式组织的健康发展。 相似文献
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农业企业化对推动农业现代化具有重大作用,要充分发挥形式多样的农民合作经济组织的作用,内外因相结合,完善农民合作经济组织,推动农业企业化进一步发展。 相似文献
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Microwave absorption by normal and tumor cells 总被引:1,自引:0,他引:1
Energy levels exist in mammalian cells which result in the absorption of microwaves between 66 and 76 gigahertz. Many of these energy levels occur when water molecules associate with the various chemical groups of macromolecules. The absorption spectra of cells between 66 and 76 gigahertz, therefore, is determined by the structure of in vivo water lattices, and these seem to reflect indirectly the structural makeup of macromolecules or macromolecular complexes. Tumor cells absorb 66-, 68-, and 70-gigahertz microwaves less strongly and 69-, 72-, and 75-gigahertz microwaves more strongly than normal cells. These differences in the strength of attenuation at each frequency suggest that either the ratio of RNA to DNA or the relative number of certain types of chemical groups in tumor cells is different from that in normal cells. 相似文献
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Using polarized light we have studied the effects of various mitotic poisons on mitotic spindles of living Pectinaria oocytes; we have studied fixed specimens with phase and electron microscopy. Vinblastine caused attrition and eventual disappearance of spindle structure as rapidly as did colcemid, and subsequent recovery from this treatment was at least as fast as that from colcemid. Griseofulvin, however, was easily the best agent for rapid, reversible, and repeated dissolution of the spindle. Agents that arrest metaphase may act on nondividing cells by interfering with the organization of other gelated structures. 相似文献
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丹参对链脲佐菌素糖尿病大鼠肝和肾组织结构的影响 总被引:2,自引:0,他引:2
[目的]观察丹参(Salvia miltiorvhiza Bunge)对链脲佐菌素(STZ)糖尿病模型大鼠肝、肾组织结构的影响,为临床预防和治疗糖尿病并发症提供参考。[方法]采用60mg/kg腹腔注射链脲佐菌素制备糖尿病大鼠模型,将符合糖尿病诊断标准的大鼠随机分为模型对照组15只和丹参治疗组15只,别设正常对照组20只。丹参治疗组灌胃丹参水煎液5ml/(kg.d),模型对照组和正常对照组灌胃相当剂量的蒸馏水,试验期为28d。试验结束后将大鼠剖杀,取肝、肾组织,Bouin液固定,常规石蜡切片,HE染色,观察切片的组织结构。[结果]与正常对照组相比,大鼠肝脏肝细胞索、肝窦排列不规则,肝细胞肿大,轻度变形。模型对照组大鼠肾小球体积增大,血管球扩张,肾小囊囊腔变小,肾小管腔里充有不等量蛋白性物,肾小管上皮细胞有脱落现象。丹参水煎液治疗组大鼠肝、肾组织形态学改变程度较轻或接近正常。[结论]链脲佐菌素复制的糖尿病模型大鼠肝、肾组织结构有一定的变化,而丹参对模型大鼠肝、肾组织结构病变有缓解作用,可见丹参对糖尿病有一定的治疗作用。 相似文献