迷失的世界(20)

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每期20题(初中用)

1.螂鱼的消化系统中,不与食物接触的器官是 )。A.肠B.食管c.气管D.肝胰脏2.有关鱼类特征的描述哪项正确()。A.心脏二腔,二腔中都为动脉血B.附月支骨与脊柱不相连C.软骨鱼的鳃有鳃盖保护D.唾液腺发达,与水生习性有关3.「列在一生的某时期里形成脊索的动物是 A. 4.位是( A. I今 C. D.海胆B.章鱼c.鸽子D义昌鱼在显微镜卜观察活金负尾部毛细血管,最好的部有血液流动的小血管血液流动尾部的血管红细胞成单行通过的血管血液;友向头部的血管卜列不属一f同一门的动物是()。大麻哈鱼B.海琢C.马面纯D.海参大多数海产鱼类不能在淡水中生存,因为…     

每期20题(高中用)

1.预防小儿麻痹症的糖丸(疫苗),必须在一定的较低温度下保存。其原因是()。 A.防止环境污染,以免病菌随疫苗服入 B.防止蛋白质变性,以免疫苗死亡失效 c.防止疫苗大量繁殖,以免服入剂量失控 D.防止蛋白质脱水分解,以免疫苗溶解失效2.与植物体中的豆固醇属于同类的物质是(). A.纤维素B.胰岛素C.叶绿素.D.性激素3.人和动物乳汁中特有的二精水解后产物是()。 A一分子葡萄糖和一分子果精 B一分子果糖和一分子半乳糖 C一分子半乳糖和一分子葡萄搪 D.二分子葡萄糖4.以下四种物质中,能构成蛋白质的物质是()。N。:_止_达一(。H {!CH之SH }NH:…     

Molecular modeling of the interaction of 17(20)Z- and 17(20)E-pregna-5,17(20)-dien-21-oyl amides with the nuclear receptor LXRβ

Eight isomeric 17(20)Z- and 17(20)E-pregna-5,17(20)-dien-21-oyl amides, conformationally rigid oxysterol analogues, differing in the structure of the amide moiety have been analyzed. Analysis of low energy conformers revealed that all 17(20)E-isomers had three main energy minima (corresponding to the values of the dihedral angle θ_20,21 (C17=C20-C21=O) about ～0°, ～120°, and ～240°); the most occupied minimum corresponded to θ_20,21 about ～0°. 17(20) Z-Isomers had either one or two pools of stable low energy conformations. Molecular docking of these compounds to the ligand-binding site of the nuclear receptor LXRβ (a potential target) demonstrated high probability of binding of E-isomers but not Z-isomers with this target. Results of the molecular modeling were confirmed by an experiment in which stimulation of triglyceride biosynthesis in Hep G2 cells in the presence of 17(20)E-3β-hydroxypregna-5,17(20)-dien-21-oyl (hydroxyethyl)amide was demonstrated.     

20世纪病毒概念的发展(代序)

在人们的心目中‘发现’是科学的象征,新发现往往容易受到重视。因此新闻界以新的发展衡量科学。当诺贝尔提出“诺贝尔奖金”条件时是以新的发现为标准,特别是对人类有益的发现。但是如果认为科学仅是事实的累积就会使人发生误解。不论在生命科学或可能同样地,在其他科学,大部分的主要进展是由于引出了新的概念,或改进了已有的概念。认     

20世纪生物科学前进的足迹(Ⅰ)

20世纪生物科学发展速度惊人 ,在众多领域都有新的发现和重大突破 ,2 0世纪取得的这些重大成果 ,使生物科学得到空前的发展和完善 ,为 2 1世纪生物科学的腾飞奠定了坚实的基础。现将2 0世纪生物科学的重大成果介绍给广大读者。190 1年△奥地利病理学家卡尔 兰德斯坦纳 (ＫａｒｌＬａｎｄｓｔｅｉｎｅｒ)发现了人的ＡＢＯ血型系统。△奥地利的休斯 (Ｅ .Ｓｕｅｓｓ)出版巨著《地球的面貌》 ,书中首次提出“生物圈”这一重要术语。△德国细菌学家贝林 (ＥｍｉｌｖｏｎＢｅｈｒｉｎｇ)由于对血清疗法特别是抗白喉血清疗法的研究及发现白喉抗毒…     

巨魔芋小学怪传 使者密令(20)

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Novel Taxa-4(20),12-diene and 2(3→20)Abeotaxane from Needles of Taxus canadensis

A novel 6/8/6-membered taxane with a rare C-12(13)-double bond and rare 2(3→20)abeotaxane were isolated from the needles of Taxus canadensis. Their structures were characterized as 7β,9α,10β-triacetoxytaxa-4(20),12-diene-2α,5α,11β-triol (1) and 2α,7β,10β-triacetoxy-5α-hydroxy-2(3→20)abeotaxa-4(20),11-diene-9,13-dione (2) on the basis of 1D and 2D spectroscopic data. 1 is the first example of a natural taxane without substitution at both C-13 and C-14.     

20世纪生物科学前进的足迹(Ⅱ)

1951年　　△阿尔农(Ａｒｎｏｎ)确认叶绿体可以产生氧气,合成ＡＴＰ,固定ＣＯ2等。△英国桑格(ＦｒｅｄｅｒｉｃｋＳａｎｇｅｒ)确定胰岛素的分子结构及氨基酸排列顺序。1952年△布里吉斯(Ｂｌｅｃｇｉｓ)研究细胞分化中核与细胞质的关系。△派拉德(Ｐａｒｄｅｅ)发现线粒体的构造是梳子状的。△法国外科医生和生物学家亨利拉博里(Ｈｅｎｒｙ.Ｌａｒｂｅｌｙ)首次使用氯丙嗪,从此揭开了精神病药理学的新纪元。△美国的盖茨(Ｇａｔｅｓ)合成吗啡。△美国的赫尔希(Ａ.Ｄ.Ｈｅｒｓｈｙ)和蔡斯(Ｍ.Ｃｈａｓｅ)实验证明脱氧核糖核酸(ＤＮＡ)是遗…     

20世纪生命科学主要成就集萃(1900～1999)

20世纪生命科学发展速度惊人 ,在众多领域都有新的发现和重大突破 ,2 0世纪取得的这些重大成果 ,使生命科学得到空前的发展和完善 ,为 2 1世纪生命科学的腾飞奠定了坚实的基础。现将 2 0世纪生命科学的重大成果介绍给广大读者。190 0年△俄国生理学家巴甫洛夫 ( I.Pavlov)发表他关于狗的消化生理学的重要著作 ,190 4年获诺贝尔奖。190 1年△奥地利病理学家卡尔·兰德斯坦纳 ( KarlLandsteiner)发现了人的 ABO血型系统。△奥地利的休斯 ( E.Suess)出版巨著《地球的面貌》,书中首次提出“生物圈”这一重要术语。△德国细菌学家贝林 ( Emil…     

氦氖激光治疗女阴溃疡20例报告(摘要)

我科使用氦氖激光局部照射治疗女阴溃疡２０例,取得满意疗效,现报告如下：１一般资料门诊病人２０例,年龄１８～４０岁,病程３月～３年。皮损部位：小阴唇１２例,大阴唇５例,尿道口阴蒂３例。２治疗方法使用ＪＹ—Ⅱ型氦氖激光机进行患处照射,波长为６３２８,输...     

近20年亚欧大陆植被指数(NDVI)对大尺度气候变化的敏感性(英文)

The influence of climate change on the terrestrial vegetation health (condition) is one of themost significant problems of global change study. The vegetation activity plays a key role in the globalcarbon cycle. The authors investigated the relationship of the advanced very high resolution radiometer-normalized difference vegetation index (AVHRR-NDVI) with the large-scale climate variations on the inter-annual time scale during the period 1982-2000 for the growing seasons (April to October). A singular valuedecomposition analysis was applied to the NDV! and surface air temperature data in the time-domain todetect the most predominant modes coupling them. The first paired-modes explain 60.9%, 39.5% and 24.6%of the squared covariance between NDV! and temperature in spring (April and May), summer (June andAugust), and autumn (September to October), respectively, which implies that there is the highest NDVIsensitivity to temperature in spring and the lowest in autumn. The spatial centers, as revealed by themaximum or minimum vector values corresponding to the leading singular values, indicate the highsensitive regions. Only considering the mode 1, the sensitive center for spring is located in westernSiberia and the neighbor eastern Europe with a sensitivity of about 0.308 0 NDVI/℃. For summer, thereare no predominantly sensitive centers, and on average for the relatively high center over 100^o-120^o E by 45^o-60^o N, the (110^o-140^o E,55^o-65^oN)sitivity is 0.248 0 NDVI/℃. For autumn, the center is located over the high latitudes ofeastern Asia (110^o-140^o E, 55^o-65^o N), and the sensitivity is 0.087 5 NDVI/℃. The coherent patters asrevealed by the singular decomposition analysis remain the same when coarser resolution NDVI data wereused, suggesting a robust and stable climate/vegetation relationship.     

Dihomogammalinolenic acid (20:3ω6) is more anti-aggregatory than eicosapentaenoic (20:5ω3) in a platelet-endothelial cell mixture

The effect of 20:3ω6, the precursor of I series prostaglandins was to inhibit platelet aggregation more strongly than either 20:5ω3, the precursor of 3 series prostaglandins or 20:3ω3 which is not a substrate of prostaglandin synthetase. When platelets and dissociated endothelial cells were pretreated with 20:3ω6, platelet aggregation in the presence of endothelial cells was much more inhibited than after 20:5ω3 pretreatment.     

莲属(Nelumbo)20个品种染色体数目及其核型分析

本文对现有野生和栽培的128个莲藕品种中,有代表性的20个品种,进行了体细胞染色体的形态结构及核型分析,发现所有品种均为二倍体,染色体基数为8,2n=16。就染色体形态结构、相对长度变化范围、著丝点位置看,各品种基本核型组成大致近似,不同点是带随体的位置数目不一,以及每对染色单体有缺失现象。这很可能会引起某些染色体产生包括易位在内的结构重组,从而导致各品种之间的差异。     

CD20F(ab'''')2抗体的发酵与纯化

转化了质粒PYZcpp^3的16C9大肠杆菌可高水平地分泌表达可溶性CD20 F(ab’)2抗体;采用经优化的培养条件,在发酵罐上进行高密度培养OD550值达140;每升湿菌菌重200g;抗体的产量每升为241mg,其中F(ab’)2片段达50％,F(ab‘)2可以特异性的识别CD20^ 细胞并与CD20相结合;F(ab‘)2对Raji细胞的IC50值为22.8μg／mL;而Fab’对Raji细胞的IC50值为45．9μg／mL。     

CD20F(ab′)2抗体的发酵与纯化

转化了质粒PYZcpp3的 16C9大肠杆菌可高水平地分泌表达可溶性CD2 0F(ab′) 2 抗体 ;采用经优化的培养条件 ,在发酵罐上进行高密度培养OD550 值达 14 0 ;每升湿菌菌重 2 0 0g ;抗体的产量每升为 2 4 1mg ,其中F(ab′) 2 片段达 5 0 % ,F(ab′) 2 可以特异性的识别CD2 0 细胞并与CD2 0相结合 ;F(ab′) 2 对Raji细胞的IC50 值为 2 2 8μg mL ;而Fab′对Raji细胞的IC50 值为 4 5 9μg mL。     

第20届国际生物学奥林匹克竞赛(10)实验考试

实验考试4 细胞生理 总分91,考试时间:90 min. 这个考试部分有下列2个任务: 任务1:研究细胞周期(61分). 任务2:研究单细胞藻类运动机理(30分). 必须把你的结果和答案写在答题纸上.回答在问卷上的答案不能得分. 请确定你拿到了所有列出的材料和设备.如果缺少,请举手示意. 考试结束时,将答题纸和问卷放回信封.考试教师会来收取.     

《细胞生物学杂志》1998年(第20卷)总目录

专论与综述 果蝇生殖细胞的性别决定小鼠原始生殖细胞的起源、迁移和增殖c一Myc和细胞凋亡·················……赵德护俞慧I:(1)李光鹏谭景和I:(4)l’”一黄行许等I:(9)l沙6细胞庄枷夸龙士J二一l刀勺厂月、‘以、一~~~~,阴,~.一一一~一~.-~~~一一一一~一~~一~一~一~~一1998年 捉血小夜生成素受体--一原癌基因c一Mp}蛋白的研究进展···············,,··,·…赵新燕杨开勇I:(招) 端粒、端粒酶与癌症关系研究的进展·······························,··········…     

近20年亚欧大陆植被指数(NDVI)对大尺度气候变化的敏感性

利用1982～2000年4～10月的AVHRR-NDVI数据,分析了大尺度的气候(温度)变化对欧亚大陆植被状况的影响.分析方法为奇异值分解,从温度和NDVI的年际变化中检测出二者最重要和最密切的大尺度空间相关特征.用每个奇异值的平方占总的协方差平方和的比例(解释率),可以度量每对模态的重要性.春季(4和5月)、夏季和秋季(9和10月)的解释率分别是60.9%、39.5%和24.6%,这说明整体上春季植被状况对温度的敏感性高于夏季和秋季.奇异值分解的显著模态中心是二者关系最密切的地区,也就是NDVI对温度最敏感的地区,春季为西西伯利亚和东欧东北部,敏感性为 0.308 0 NDVI/℃;夏季没有特别突出的敏感中心,选择与计算春季相同格点数的高值中心,其敏感性为 0.248 0 NDVI/℃;秋季敏感中心在亚洲东部高纬度地区,相同格点大小范围(110°～140° E,55°～65°N)平均敏感性为 0.087 5 NDVI/℃.这种大尺度的NDVI-气温的关系及其敏感性非常稳定,并不随使用的NDVI的空间分辨率的改变而改变.     

Inhibitors of human 20α-hydroxysteroid dehydrogenase (AKR1C1)

Human 20α-hydroxysteroid dehydrogenase (AKR1C1), a member of the aldo-keto reductase (AKR) superfamily, is one of four isoforms (with >84% amino acid sequence identity) existing in human tissues. AKR1C1 most efficiently reduces biologically active progesterone and 5α-pregnan-3α-ol-20-one into their corresponding 20α-hydroxysteroids among the isoforms. The enzyme also accepts endogenous and xenobiotic non-steroidal carbonyl compounds as the substrates. In addition to the up-regulation of the AKR1C1 gene in cancer cells, the enzyme's over-expression in the cells of lung, ovary, uterine cervix, skin and colon carcinomas was reported to be associated with resistance against several anticancer agents. Thus, AKR1C1 may be a marker of the above cancers and a target of poor prognosis in cancer therapy. The recently determined X-ray crystal structures of AKR1C1/NADP(+)/20α-hydroxyprogesterone and AKR1C1/NADP(+)/3,5-dichlorosalicylic acid ternary complexes have provided a strong foundation for structure-based design methods to improve inhibitor selectivity and potency. In this review we provide an overview of the different types of AKR1C1 inhibitors and an update on the design of potent and selective inhibitors based on the crystal structure of the enzyme-inhibitor complex. Article from the Special issue on Targeted Inhibitors.