共查询到20条相似文献,搜索用时 180 毫秒
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《小哥白尼(野生动物画报)》2011,(5)
哎呀呀,这个世界乱套了!大人变成了小孩,小孩变成了大人。现在,终于轮到各位小酷想家来当家做主了,快来看看他们都有什么出色的表现吧!看到爸妈变成了小孩,我立马学着他们的样子,下达了第一道命令:写作业去!我想他们一定会哭的,因为老师留的作业实在是太多了。新浪YOYO 相似文献
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本文叙述了我国生物材料专利制度的变迁,耐我国生物材料的专利保护范围进行了论述,对生物材料的保藏问题进行了说明;对我国生物材料保护制度进了论述,并对我国生物材料领域的专利现状进行了分析,就如何加强我国生物材料的专利保护提出几点建议。 相似文献
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2008年9月,美国孟山都(Monsanto)公司宣布已经查清了与玉米增收相关的遗传信息,找到了粮食增产的新途径。
孟山都公司从其产量最高的雌株玉米中挑选了1株,绘制出了其遗传基因的蓝图。这次研究对于将来向农户提供优质玉米种子至关重要,它采用了高通量DNA测序法.并利用了最近刚完成的玉米基因组计划所获得的数据。 相似文献
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叙述了生物信息学中途径的研究背景;综述了近几年来相关途径及生物化学数据库及其特点;介绍了有关的途径分析方法.同时对于途径研究应用作了展望. 相似文献
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1985年4月用标志重捕法观察了大仓鼠的活动范围;野外直接观察了鼠的活动及危害;室内直接观察了昼夜活动节律;在笼养状况下,观察了大仓鼠捕食黑线仓鼠和小白鼠的行为;室内观察了大仓鼠选食种子的行为。 相似文献
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中华猕猴桃良种选育研究 总被引:1,自引:0,他引:1
黄仁煌;武显维;王圣梅;洪树荣;宋元珍;陈前綷 《武汉植物学研究》1986,4(3):263-269
本文扼要叙述了中华猕猴桃原产地的生态条件,分析了引入栽培园中所遇到的突出问题,提出了中华猕猴桃从高海拔山区引入低海拔丘陵平原应解决的关键技术,初步总结了在武汉风土条件下的栽培经验,简述了优株选育途径和效果,介绍了武植3号等优良品系的主要经济性状。 相似文献
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综述了近年来乌龙茶品质的研究进展,介绍了乌龙茶的感官品质特征,阐述了乌龙茶的理化品质特征和相关药理作用,分析了影响乌龙茶品质的主要因素,概述了乌龙茶品质研究技术,提出乌龙茶品质下一步的研究重点方向。 相似文献
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沙冬青淀粉粒及其与叶绿体发育的关系 总被引:5,自引:0,他引:5
沙冬青叶绿体中的淀粉粒一般为1-3个,主要有4种类型。第1种外周部分电子密度较高,中央部分较低,但每个部分的电子密度十分均匀。它们近似椭圆形,附近的类囊体形态正常,结构清晰。第2种电子密度由外向内逐渐变低,多为椭圆形,附近的类囊体较清晰。第3种外周部分的电子密度很高,中央部分不均匀,形状多种多样,附近的类囊体有的不清晰。第4种电子密度很低,十分均匀,形状不规则,附近的类囊体已经解体或正在解体。分析表明,淀粉的形态变化明显与叶绿体发育有关。 相似文献
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Failure to Maintain Glycolysis in Anoxic Nerve Terminals 总被引:8,自引:6,他引:2
Synaptosomal glycolysis is stimulated eight- to 10-fold when the respiratory chain is inhibited by cyanide or by anoxia. However, the stimulation is transient and after 15 min declines toward the preanoxic rate. The decline is not seen when Ca2+ is absent or when the respiratory chain is inhibited by rotenone. The decline in glycolysis is reversible, is not due to substrate exhaustion, and is the cause, rather than the effect, of lowered synaptosomal ATP/ADP ratios. The failure to maintain glycolysis when the terminal oxidase of the respiratory chain is inhibited may have relevance to the sensitivity of the brain to anoxic damage. 相似文献
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药敏药片经临床对金黄色葡萄球菌、大肠埃希氏菌、铜绿假单胞菌等235株考核.表明药片工艺研究先进,药片与培养基结合牢固,无断裂、崩解,不渗出颗粒,抑菌圈呈同心园扩散.边缘清楚。药物含量均匀,释放度好。药片抑菌差仅1~3mm;而纸片抑菌差为2~12mm。药片变黑系数CV为2.71~4.21;而纸片CV为3.82~14.36。表明纸片片间差大,药片精密度明显好于纸片。 相似文献
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《Journal of biological dynamics》2013,7(4):415-427
A general three-stage discrete-time population model is studied. The inherent net reproductive number for this model is derived. Global stability of the origin is established provided that the inherent net reproductive number is less than one. If it is larger than one the existence of a unique positive fixed point is proved and the persistence of the system is established. Finally, for certain parameter ranges global stability of the positive fixed point is proved. 相似文献
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For a subdivided population the consequences of dominance and gene flow for the maintenance of multilocus polymorphism, local adaptation, and differentiation are investigated. The dispersing population inhabits two demes in which selection acts in opposite direction. Fitness is determined additively by two linked diallelic loci with arbitrary intermediate dominance (no over- or underdominance). For weak as well as strong migration, the equilibrium structure is derived. As a special case, a continuous-time continent–island model (CI model) is analyzed, with one-way migration from the continent to the island. For this CI model, the equilibrium and stability configuration is obtained explicitly for weak migration, for strong migration, for independent loci, and for complete linkage. For independent loci, the possible bifurcation patterns are derived as functions of the migration rate. These patterns depend strongly on the degree of dominance. The effects of dominance, linkage, and migration on the amount of linkage disequilibrium (LD) and the degree of local adaptation are explored. Explicit formulas are obtained for and (the squared correlation in allelic state). They demonstrate that dominant island alleles increase and decrease . Local adaptation is elevated by dominance of the locally adaptive alleles. The effective migration rate at a linked neutral locus is calculated. If advantageous alleles are dominant, it is decreased only slightly below the actual migration rate. For a quantitative trait that is determined by two additive loci, the influence of dominance on measures of differentiation is studied. Explicit expressions for and two types of at equilibrium are deduced and their relation is discussed. 相似文献
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短柄五加大,小孢子发生和雌,雄配子体发育的研究 总被引:6,自引:2,他引:4
短柄五加花药5枚,每个花药四个花粉囊。小孢子母细胞减数分裂时,胞质分裂为同时型,产生正四面体形的四分体。花药壁由表皮、药室内壁、中层和绒毡层四层细胞组成,其发育类型为双子叶型。腺质绒毡层,其细胞为二核。三细胞型花粉。子房5室,每室两个胚珠,上胚珠败育,下胚珠可育。下胚珠倒生,具单珠被,厚珠心。大孢子母细胞减数分裂形成线性排列的四个大孢子,雌配子体发育属蓼型。开花当天,花粉散开,雌配子体尚未成熟,处 相似文献
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羚牛(Budorcas taxicolor)部分脏器特点的观察 总被引:2,自引:2,他引:0
本文对2只羚牛的雌性生殖器官及肝、肾、脾等脏器进行了形态描述,并与黄牛及羊的相应器官进行了比较,为探讨羚牛的分类地位提供了解剖学资料。 相似文献
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清栓酶治疗脑血栓冠心病微循环变化初步观察 总被引:2,自引:0,他引:2
本文报导40例脑心血管疾病在清栓酶治疗前后进行甲皱微循环对比观察,其中脑血栓组20例,冠心病组20例,两组均在清栓酶治疗2~3疗程后复查,分别对其甲皱微循环微血管袢的形态及功能,血液流态和微血管周围变化等三方面进行治疗前后对比观察,结果发现,治疗前甲皱微循环改变是明显的,临床症状较重,治疗后甲皱微循环障碍均得到了明显改善,临床症状也随着减轻或消失。治疗前后比较,其差异有显著的意义 P<0.05,P<0.01.从临床对比观察所见,脑心血管疾病的微循环改变与病情有关,其改变与病情轻重相吻合,与疾病转归相一致,提示微血管病变是动脉硬化临床可识别的象征.微循环障碍与疾病的发生发展有着内在联系,是脑心血管疾病的病因和发病的中间环节.治疗后微循环障碍的明显改善,提示清栓酶有着较好的改善微循环的功能. 相似文献
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In this paper, we quantify the extent to which shoulder orientation, upper-arm electromyography (EMG), and forearm EMG are predictors of distal arm joint angles during reaching in eight subjects without disability as well as three subjects with a unilateral transhumeral amputation and targeted reinnervation. Prior studies have shown that shoulder orientation and upper-arm EMG, taken separately, are predictors of both elbow flexion/extension and forearm pronation/supination. We show that, for eight subjects without disability, shoulder orientation and upper-arm EMG together are a significantly better predictor of both elbow flexion/extension during unilateral () and mirrored bilateral () reaches and of forearm pronation/supination during unilateral () and mirrored bilateral () reaches. We also show that adding forearm EMG further improves the prediction of forearm pronation/supination during unilateral () and mirrored bilateral () reaches. In principle, these results provide the basis for choosing inputs for control of transhumeral prostheses, both by subjects with targeted motor reinnervation (when forearm EMG is available) and by subjects without target motor reinnervation (when forearm EMG is not available). In particular, we confirm that shoulder orientation and upper-arm EMG together best predict elbow flexion/extension () for three subjects with unilateral transhumeral amputations and targeted motor reinnervation. However, shoulder orientation alone best predicts forearm pronation/supination () for these subjects, a contradictory result that merits further study. 相似文献