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1.
阿尔茨海默病(AD)已成为威胁老年人生活的一种常见病,对老年人的生活质量有着严重的影响,目前尚无有效地防治方法。最新研究发现在阿尔茨海默病的病理发生中,神经细胞伴有显著的线粒体代谢紊乱和动态变化的异常,其中动力相关蛋白1(Drp1)是参与线粒体动态变化的关键分子。深入研究阿尔茨海默病中线粒体动态变化的异常及Drp1等关键分子的作用机制,对于揭示AD的发生机制及寻找药物作用靶点具有重要意义。综述了Drp1在阿尔茨海默病中的调控机制。  相似文献   

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Two different glucans (PS-I, water-soluble; and PS-II, water-insoluble) were isolated from the alkaline extract of fruit bodies of an edible mushroom Calocybe indica. On the basis of acid hydrolysis, methylation analysis, periodate oxidation, and NMR analysis ((1)H, (13)C, DEPT-135, TOCSY, DQF-COSY, NOESY, ROESY, HMQC, and HMBC), the structure of the repeating unit of these polysaccharides were established as: PS-I: →6)-β-D-Glcp-(1→6)-β-D-glcp-(1→6)-)-β-D-Glcp-(1→ α-D=Glcp (Water-soluble glucan). PS-II: →3)-β-D-Glcp-(1→3)-β-D-glcp-(1→3)-)-β-D-Glcp-(1→3)-β-D-Glcp-(1→ β-D-Glcp (Water-insoluble glucan, Calocyban).  相似文献   

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问题解答(1)     
问:绿色植物在有阳光时行光合作用吸二氧化碳放出氧气,在晚上没阳光时只有呼吸作用吸氧气放二氧化碳,为什么总说早晨到树林中散步空气好呢? 答:因为空气流动得很厉害,所以在一般树林中白天夜晚O_2及CO_2含量的改变是极小的.说早晨空气好,并不是植物起了什么作用,而是因为夜间人们的活动停止了,车马不在路上奔驰了,工厂的烟囱不冒烟了.加上树林中的湿度较大,尘土都降落在地上,空气就更为清洁了.我们夜间睡在屋中,屋中温度较高,不好气味的有机物(器物中发出或人呼出)空气中也很多,所以一到树林中,凉爽而清洁的空气,眼界的开朗就使我们心神为之一振.(吴相钰、董愚得答)  相似文献   

4.
Δ(8)-Tetrahydrocannabinol (26), 3-(1',1'-dimethylbutyl)- (12), 3-(1',1'-dimethylpentyl)- (13), 3-(1',1'-dimethylhexyl)- (14) and 3-(1',1'-dimethylheptyl)-Δ(8)-tetrahydrocannabinol (15) have been converted into the corresponding 1-bromo-1-deoxy-Δ(8)-tetrahydrocannabinols (25, 8-11). This was accomplished using a protocol developed in our laboratory in which the trifluoromethanesulfonate of a phenol undergoes palladium mediated coupling with pinacolborane. Reaction of this dioxaborolane with aqueous-methanolic copper(II) bromide provides the aryl bromide. The affinities of these bromo cannabinoids for the cannabinoid CB(1) and CB(2) receptors were determined. All of these compounds showed selectivity for the CB(2) receptor and one of them, 1-bromo-1-deoxy-3-(1',1'-dimethylhexyl)-Δ(8)-tetrahydrocannabinol (10), exhibits 52-fold selectivity for this receptor with good (28nM) affinity.  相似文献   

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T.(T.)vicinus(Edwards,1914)(附近杵蚊)在我国有比较广泛的记载。它和bam-busa(Yamada,1917)(竹生杵蚊)近似。Edwards的原描述比较简单,并限于成蚊。实际两者的主要区别除了Edwards提到的本种前足跗瓜的特征外在于:vicinus雄蚊第九腹节背叶宽而末端高度倾斜,各具刚毛25根以上,幼虫的栉齿至少部分生在骨片上,腹刷毛  相似文献   

7.
领蚊Heizmannia是亚热带丛林和竹林中的吸血蚊类之一,但我国过去除台湾省外对它们所知不多。近年来我们在广东(海南岛)、广西、江西、福建、云南等山区采到了8种领蚊,包括3种我国新纪录,本文报告的H.(M.)achaetae(Leicester,1908)(无鬃领蚊)即为其中之一。  相似文献   

8.
The present paper, mainly dealing with phytogeographical, Cytological and Palynolo gical studies on Chinese Stachyuraceae, is the first part of a series of contributions to systematics of this family. As we know, Stachyuraceae, a monogeneric family, is endemic to East Asia, with a strong differentiation in China. Systematic position of the family is still uncertain. Undoubtedly, multidisciplinary studies on it wisl give a better understanding of plant differentiation in East-Asiatic floristic region and systematic position of the family. The distribution of all the 9 Chinese species of Stachyurus have been studied on the basis of morphogeographical method. The status of some taxa has been changed as follows: Stachyurus chinensis Franch. ssp. latus (Li) Y. C. Tang et Y. L. Cao, stat. nov. S. chinen-sis Franch. Ssp. cuspidatus (Li) Y. C. Tang et Y. L. Cao, stat. nov. S. chinensis Franch. ssp. brachystachyus (C. Y. Wu et S. K. Chen) Y. C. Tang et Y. L. Cao, stat. nov. S. salicifolius Franch. ssp. lancifolius (C. Y. Wu) Y. C. Tang et Y. L. Cao, stat. nov., S. yunnanensis Franch. var. pedicellatus Rehd. and S. oblongifolius Wang et Tang being reduced as synonyms of S. yunnanensis Franch. From morphological point of view, we would consider that sect. Callosurus is more primitive and its present area might be the preservation center of the family. In this paper the chromosome numbers of 5 taxa, i.e. Stachyurus yunnanensis, S. chinensis ssp. chinensis, S. chinensis ssp. cuspidatus, S. salicifolius ssp. salicifolius, S. retusus, are reported for the first time. Along with the chromosome countings of S. himalaicus and S. sigeyosii by S. kurosawa, we come to the conclusion that all the species so far studied have 24 small somatic chromosomes (2n=24). The pollen grains of 6 taxa, i.e. Stachyurus yunnanensis, S. obovatus, S. himalaicus, S. chinensis ssp. chinensis, S. salicifolius ssp. salicifolius, S. retusus were also examined. Together with the observations of G. Erdman and Huang Tsengchien on S. himalaicus, it seems that the pollen grains of the genus Stachyurus are rather uniform in morphology. The pollen grains of sect. Callosurus are tricolporoidate, while those of sect. Stachyurusare tricolporate. Two pollen types, representeb by the two sections, though not strongly distinct, may be considered as further evidence of the validity of the two taxa as section. Sexuality of flowers is also disscussed in the paper. According to our observationon six species, i.e. Stachyurus yunnanensis, S. obovatus, S. himalaicus, S. chinensis, S. salicifolius, S. retusus, the plants are dioecious, which supports T. Makino's observation on S. praecox and H. Hara's on S. himalaicus. Female flowers have relatively large pistils and short stamens with empty anthers, while male flowers have smaller sterile pistils and longer stamens with well developed anthers. Decontaminated thianthrene disproportion. 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Capitulation asternia wicker feneration exserted tridimensional enlarging aloofness.  相似文献   

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A fluorescent analog of angiotensin II was synthesized by reacting fluorescein 5′-isothiocyanate with (Asp1, Ile5)-angiotensin II. Nα-(N-Fluoresceinthiocarbamoyl)-(Asp1, Ile5)-angiotensin II was purified by chromatography on DEAE-cellulose and Sephadex G-25. Analysis of the analog by thin-layer chromatography, thin-layer electrophoresis, and reversed-phase high-performance liquid chromatography indicated that the analog was free of angiotensin II and fluorescein 5′-isothiocyanate. N-Terminal sequence analysis demonstrated that fluorescein 5′-isothiocyanate reacted with the N-terminal aspartic acid residue of angiotensin II. Nα-(N-Fluoresceinthiocarbamoyl)-(Asp1, Ile5)-angiotensin II has an absorption maximum at 492 nm, and the value of the molar extinction coefficient, ?, is 7.7 × 104m?1 cm?1. The fluorescence emission maximum occurs at 520 nm. Infusion of the analog (0.69 μg/min/kg body wt) directly into the renal artery of an anesthetized rat reduced the blood flow by 12 to 27% within 2 min. Infusion of angiotensin II (0.48 μg/min/kg body wt) reduced renal arterial blood flow by 35 to 53% within 2 min. Saralasin, a partial agonist and antagonist of angiotensin II, inhibited the biologic effect of the fluorescent analog and angiotensin II by 75 and 70%, respectively. The purity, spectral properties, and in vivo biologic activity of Nα-(N-fluoresceinthiocarbamoyl)-(Asp1, Ile5)-angiotensin II indicate that this analog should facilitate characterization of angiotensin II receptors.  相似文献   

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This computational study is intended to shed light on the crystalline and molecular structure, together with the hydrogen bonding (H-bonding) differences between two forms of native cellulose. DFT calculations were carried out to characterize the 17O, 1H and 13C nuclear magnetic resonance (NMR) parameters in cellulose Iα and Iβ with the B3LYP functional employing the 6–311++G7 and 6–31+G1 basis sets. Geometry optimization revealed that the average HB length is shortened by 0.01–0.08 Å when the chains are aligned, whereas the average bond angle increases by about 4–8° exhibiting the enhancement of HB strength. For the isolated cellotetramer chains, the isotropic 17O–H chemical shifts were plotted as a function of HB length. Our results indicated that as the HB length in cellotetramer Iα increases, the 17O–H chemical shift isotropy increases, but this parameter changes in the opposite direction for the other structure. Moreover, B3LYP/6–311++G7 calculations reveal that there is an acceptable correlation between the calculated 13C chemical shifts of the two structures and their experimental values.  相似文献   

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1963年12月18日至1964年1月14日,笔者等在海南吊罗山的南喜及小妹林场进行了20多天的昆虫调查,采得昆虫标本一批,共计有15个目120余科。吊罗山位于海南岛东南部陵水县西北,东经104°5',北纬23°9',最高峰拔海1290米,林木以常绿阔叶林为主。年平均气温24.7℃,年平均降雨量1623.9毫米。我们调查期间正值冬季,所采昆虫标本比夏季的少,但仍有一定代表性。因为当时在广东大陆地区,野外能见到的昆虫为数不多,而陵水县12月份平均气温达20°8C,1月份平均气温19.6℃,在吊罗山林区仍然是“彩蝶纷飞”,调查期间出现的种类,主要是蝶类、直翅目、半翅目、双翅目、  相似文献   

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