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41.
根据系统保种理论有关保种和选择可以相互结合的观点,本文提出了保种-选择指数的概念、导出了适于各种资料条件和各种保种与选择目的的通用保种-选择指数公式、并探讨了该公式在几种特殊情况下的形式,为国内大量地方品种保种选育提供了必要的理论和方法。 相似文献
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银杏外种皮的双黄酮成分 总被引:9,自引:0,他引:9
从银杏外种皮的乙酸乙酯提取中分离得到6个化合物,其中5个经物理常数及光谱分析鉴定为金松双黄酮、银杏素、奶杏素、1-5’-甲氧基白果素及白果素。这些化合物均首次从银杏外种皮分离。 相似文献
44.
戊肝病毒活性肽的选择,合成与应用 总被引:3,自引:0,他引:3
对戊型肝炎病毒(HEV)编码蛋白序列进行了亲水性分析及二级结构预测,选择亲水性强、具有β-转角与β-折叠的区段,采用多肽固相合成法合成了HEV基因组3个开读框架(ORF1,ORF2和ORF3)中可能的抗原表位,以免疫学方法进行鉴定并选出了分别来自HEV3个ORF的、具有重要生物活性与应用前景的3段肽(EH174、EH265、EH362)。在此基础上,进行了抗HEVELISA新型检测试剂盒的实验室研究及临床试用。结果表明,所研究的戊肝抗体检测试剂盒特异性高、临床符合性好、具有可重复性,在戊肝辅助诊断及流行病学调查中具有重要意义。 相似文献
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46.
Corticotropin-releasing hormone (CRH) has been shown to be a central mediator for most, if not all, stress-induced responses. Since stressful stimuli may decrease hypothalamic tuberoinfundibular and tuberohypophysial dopaminergic neuronal activities, we aimed to determine whether CRH is involved. Using central administration of various doses of ovine CRH (oCRH; 1, 3 and 10 µg/rat) into the lateral cerebroventricle of either male or female rats, the neurochemical changes in various parts of the central nervous system, including the hypothalamus, were determined by high-performance liquid chromatography at various times after the injection (30, 60, 120 and 240 min). The concentrations of 3,4-dihydroxyphenylacetic acid (DOPAC) and 3-methoxy-4-hydroxy-phenylethyleneglycol (MHPG), two major metabolites of dopamine and norepinephrine, respectively, in discrete brain regions were used as indices for catecholaminergic neuron activity. Plasma corticosterone levels increased significantly after all doses of oCRH and at all time points studied. oCRH also exerted significant stimulatory effects on noradrenergic neuron terminals in the frontal cortex, and on dopaminergic neuron terminals in the nucleus accumbens, hypothalamic paraventricular and periventricular nuclei, and intermediate pituitary lobe. Dopaminergic neuron terminals in the median eminence and the neural lobe of the pituitary, however, were not affected. There was no major difference in the responses between male and female rats. We conclude that CRH has a differential effect on central catecholaminergic neurons. 相似文献
47.
A novel inhibitor of cyclin-Cdk activity detected in transforming growth factor beta-arrested epithelial cells. 总被引:22,自引:5,他引:17 下载免费PDF全文
J M Slingerland L Hengst C H Pan D Alexander M R Stampfer S I Reed 《Molecular and cellular biology》1994,14(6):3683-3694
Transforming growth factor beta (TGF-beta) is a potent inhibitor of epithelial cell growth. Cyclins E and A in association with Cdk2 have been shown to play a role in the G1-to-S phase transition in mammalian cells. We have studied the effects of TGF-beta-mediated growth arrest on G1/S cyclins E and A. Inhibition of cyclin A-associated kinase by TGF-beta is primarily due to a decrease in cyclin A mRNA and protein. By contrast, while TGF-beta inhibits accumulation of cyclin E mRNA, the reduction in cyclin E protein is minimal. Instead, we find that the activation of cyclin E-associated kinase that normally accompanies the G1-to-S phase transition is inhibited. A novel inhibitor of cyclin-Cdk complexes was detected in TGF-beta-treated cell lysates. Inhibition is mediated by a heat-stable protein that targets both Cdk2 and Cdc2 kinases. In G0-arrested cells, a similar inhibitor of Cdk2 kinase was detected. These data suggest the existence of an inhibitor of cyclin-dependent kinases induced under different conditions to mediate antiproliferative responses. 相似文献
48.
RFLP tagging of a new semidwarfing gene in rice 总被引:6,自引:0,他引:6
C. Z. Liang M. H. Gu X. B. Pan G. H. Liang L. H. Zhu 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1994,88(6-7):898-900
A new rice semidwarfing gene which is not allelic tosd1, temporarily designated assdg, might be of use as a new source of semidwarfism in rice breeding programs. We report here the identification of a DNA marker closely linked to this gene. The DNA marker was identified by testing 120 mapped rice RFLP makers as hybridization probes for Southern analysis of a pair of nearly isogenic lines with or withoutsdg. Linkage association of the marker with the gene was verified using a F2 population segregating for semidwarfism. RFLP analysis showed thatsdg is closely linked to a single-copy DNA clone RZ182 on chromosome 5, with a distance of 4.3 centiMorgans between them. This marker may facilitate early selection for the semidwarfing gene in rice breeding programs 相似文献
49.
In order to study the differentiation of Asian colobines, fourteen variables were analysed in one way, on 123 skulls, includingRhinopithecus, Presbytis, Presbytiscus, Pygathrix, andNasalis with both cluster and differentiated functions tests. Information on paleoenvironment changes in China and South-East Asia
since late Tertiary have been used to examine the influences of migratory habits and the distribution range in Asian colobines.
The cladogram among different Asian colobines genera was made from the results of various analysis. Some new points or revisions
were suggested: 1. Following the second migratory way, ancient species of Asian colobines perhaps passed through Xizang along
the northern bank of Tethis sea and Heng-Duan Shan regions, across Yunnan into Vietnam, since the ancient continent between
Yunnan and Xizang was already located in on eastern bank of Tethis sea. Thus, during the evolution, Asian colobines must have
had two original centres, i.e. “Sundaland” and Heng-Duan Shan Chinese regions; 2. Pygatrix possesses a lot of cranial features
more similar toPresbytiscus than toRhinopithecus. The small difference from the modification combinesPygatrix with other two genera as shown by Groves (1970), but it is better to putPygatrix andPresbytiscus together as one genus; 3.Nasalis (2n=48) may be the most primitive genus within Asian colobines. Some features shared withRhinopithecus, for example body size, terrestrial activities, limb proportion etc. ...seem to be considered as a common inheritance of
symlesiomorphus characters; 4.Rhinopithecus, with reference to cranioface and cranium or to its origin, is a special genus of Asian colobine. It may represent the highest
level of evolutionary position within various genera (Peng et al., 1985). 相似文献
50.
Six cases of mother-cub relationships in wild giant pandas (Ailuropoda melanoleuca) were observed in the Qinling Mountains, China. It was found that panda cubs are normally left alone in the den for 4–8 h while mothers forage. The mother's absence during bouts of foraging should be considered when rescuing abandoned cubs in order to avoid adding to the decline of the wild population. © 1994 Wiley-Liss, Inc. 相似文献