992 resultados para 756
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海藻是海洋生物中的一大类群,由于其特殊的生活环境,能够代谢产生大量结构独特多变和活性特殊多样的代谢产物,是化学和生物活性多样性研究的重要对象之一。我国海域辽阔,海藻资源丰富,为寻找结构新颖、生理活性独特的先导化合物,加强对海藻资源的开发利用,本论文对中国沿海的三种海洋红藻进行了化学成分和生物活性研究,同时对山东青岛海域生物量丰富的一种海洋红藻松节藻进行了动物体内抗糖尿病活性研究。 利用正相硅胶柱色谱、Sephadex LH-20柱色谱以及反相HPLC和重结晶等现代分离手段,对山东青岛沿海的红藻扇形叉枝藻(Gymnogongrus flabelliformis)进行了系统的化学成分研究,从中得到单体化合物26个,通过波谱学方法(IR、MS、NMR等)鉴定了他们的结构,分别为(3R,6R,7E)-(+)-3-O-phenylacetyl- 4,7-megastigmadiene-9-one(1),(3R,7E)-(-)-3-O-phenylacetyl-5,7-megastigmadiene -9-one(2),(3S,6R,7E)-(+)-3-hydroxyl-4,7-megastigmadien-9-one(3),(3S,5R,6S,7E)- (-)-3-hydroxy-5,6-epoxy-7-megastigmene-9-one(4),(3S,5S,6R,7E)-(+)-3-hydroxy- 5,6-epoxy-7-megastigmene-9-one(5),Dehydrovomifoliol(6),(3R)-(-)-4-[(2R,4S)-4- acetoxy-2-hydroxy-2,6,6-trimethylcyclohexylidene]-3-buten-2-one(7),2,3,3′-三溴-4,4′,5,5′-四羟基-1′-乙氧甲基双苯基甲烷(8),2,2′,3,3′-四溴-4,4′,5,5′-四羟基双苯基甲烷(9),3-溴-4,5-二羟基苯甲醛(10),2,3-二溴-4,5-二羟基苯甲基甲醚(11),2,3-二溴-4,5-二羟基苯甲醇(12),N, N-二甲基酪胺(13),4-羟基苯甲酸乙酯(14),4-羟基苯甲基乙醚(15),4-羟基苯乙基乙酯(16),4-羟基苯乙酸甲酯(17),4-羟基苯甲醛(18),豆甾-4-烯-3-酮(19),胆甾-4-烯-3-酮(20),胆甾醇(21),尿嘧啶(22),尿嘧啶核苷(23),腺嘌呤核苷(24),丁二酸(25),5-羟基-4-甲基-5-戊基-2,5-二氢呋喃-2-酮(26)。其中化合物1、2为新化合物,化合物3为新天然产物,所有化合物均为首次从该属海藻中分离得到。通过 MTT 法对部分单体化合物进行了肿瘤细胞毒活性筛选, 结果表明,化合物8、9、10、12对筛选的所有细胞株均有较强细胞毒活性,化合物11对人肺癌细胞株(A549)、人肝癌细胞株(Bel 7402)、人结肠癌细胞株(HCT-8)有一定细胞毒活性。通过研究单体化合物对小鼠腹腔巨噬细胞TNF-分泌的影响,对其进行抗炎活性筛选,结果表明,化合物8、9、11、13、17、23、24、25对小鼠腹腔巨噬细胞TNF-分泌表现出明显的抑制作用。 从采自山东荣成镆铘岛的红藻小珊瑚藻(Corallina pilulifera)的乙酸乙酯萃取物中分离得到16个单体化合物,通过波谱学方法鉴定化合物结构14个(另外2个正在鉴定中),分别为2α-乙氧酰基-2β-羟基-A-降胆甾-5-烯-4-酮(27),胆甾-4-烯-3-酮(28),胆甾醇(29),3β-羟基-胆甾-5,24(28)-二烯-7-酮(30),2α-羟基-胆甾-4-烯-3-酮(31),6α-羟基-胆甾-4-烯-3-酮(32),3β-羟基-胆甾-5-烯-7-酮(33),(E)-phytol epoxide(34),Phytenal(35),3,7,11,15- tetramethyl-hexadec-2-en-1-oll(Phytol)(36),Loloilide(37),(3S,5R,6S,7E)-(-)-3-hydroxy-5,6-epoxy-7- megastigmene-9-one(38),Dehydrovomifoliol(39),4-羟基苯甲醛(40)。其中,化合物 31为新天然产物,化合物27为首次从植物中分离得到,所有化合物均为首次从该种海藻中分离得到。通过 MTT 法对分离得到的单体化合物进行了肿瘤细胞毒活性筛选,化合物27和化合物32对筛选的所有肿瘤细胞株均有细胞毒活性,且化合物27对人胃癌细胞株(BGC-823)、人结肠癌细胞株(HCT-8)和人卵巢癌细胞株(A2780)具有中等强度抑制活性。化合物28、化合物31和化合物33对人肝癌细胞株(Bel 7402)、人结肠癌细胞株(HCT-8)和人卵巢癌细胞株(A2780)有一定细胞毒活性。 从采自广西北海涠洲岛的多管藻Polysiphonia sp.的乙酸乙酯萃取物中分离得到6个单体化合物,通过波谱学方法鉴定化合物结构5个(另外1个仍在鉴定),分别为胆甾醇(41),3,7,11,15-tetramethyl-hexadec-2-en-1-ol(Phytol)(42),3-吲哚甲醛(43),4-羟基苯甲醛(44),4-羟基苯甲酸(45)。 对山东青岛沿海的松节藻 (Rhodomela confervoides) 乙醇提取物进行了初步的体内抗糖尿病活性研究,采用链脲佐菌素诱导的2型糖尿病(STZ-DM)大鼠模型对其进行体内降糖实验,结果发现,松节藻乙醇提取物在糖尿病大鼠体内不仅具有显著的降血糖作用,且呈现良好的量–效关系,而且能够纠正糖尿病引发的物质代谢紊乱,增加体重,提高试验动物的成活率,因此具有良好的应用开发前景。
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卤虫(Artemia)是一种广温、耐高盐的小型甲壳动物,广泛分布于内陆盐湖和沿海盐田中。卤虫的无节幼体作为重要的蛋白优质饵料,被广泛的应用于水产养殖生产。卤虫具有特殊的生物学特性,是研究甲壳动物胚胎发育的良好的实验材料,同时也是一种研究动物抗逆机制的模式动物。卤虫有卵生和卵胎生两种繁殖后代的方式,当环境条件适宜时,卤虫倾向于采取卵胎生方式,即直接产生无节幼体;而在恶劣的环境条件下,卵生方式占主要地位,产生处于滞育状态的、具有复杂外壳的休眠卵。卤虫的滞育卵具有独特的生物学特性和特殊的生理生化特点。其发育停滞,细胞分裂停止,酶活力下降,代谢活动受到抑制并可耐受各种极端恶劣环境,如缺氧、低温、紫外线、干燥等。即使在最适的环境中滞育卵的孵化率也很低,只有受到某些特定的非生物信号的刺激才自能终止这种滞育状态,恢复生理代谢;当环境条件适宜时,能够继续发育孵化成无节幼体。因此,卤虫的滞育卵在卤虫的整个生活史中占有重要的地位。另一方面,卤虫是极端环境生物,能够抵抗各种恶劣环境胁迫刺激,因此是研究抗逆机理的良好的实验动物。 本论文利用蛋白质组学技术,研究了卤虫滞育卵及滞育卵发育过程中的蛋白质组表达情况,并研究了卤虫幼体在重金属刺激后蛋白表达的变化情况。得到如下结果: 建立了中华卤虫滞育卵可溶性总蛋白的双向凝胶电泳对照图谱。在pH 4–7、分子量10-100 kDa范围内,检测到约 233个蛋白点,并利用高效液相色谱-质谱联用(LC-ESI-MS/MS)技术鉴定了其中的48个丰度较大及感兴趣的蛋白点,根据这些蛋白的生物学功能进行分类,功能类别包括细胞防御蛋白、抗氧化蛋白、细胞骨架蛋白、代谢相关蛋白等。在卤虫滞育卵中共分离鉴定到6个分子量和等电点存在差异的小热休克蛋白p26的异构体,生物信息学分析表明该蛋白有三种不同的功能位点,分别是蛋白激酶C磷酸化位点,Casein 激酶II磷酸化位点及 N-myristoylation 位点。 采用低温脱水的方法对滞育卵进行激活刺激,并对活化卵和滞育卵蛋白表达图谱进行了对比分析。结果表明对卤虫滞育卵的激活刺激引起了其蛋白表达的明显变化。活化卵图谱中蛋白点总数比滞育卵中明显增多,特别是在pI<5.5范围内。约70个蛋白点在激活刺激后上调表达,包括部分只在激活卵中表达的蛋白;25个下调表达,包括部分只在滞育卵中表达的蛋白;其余约60%(占滞育卵蛋白点数目百分比)的蛋白点表达量基本恒定。热休克蛋白家族、抗氧化蛋白家族成员等蛋白变化明显,小热休克蛋白p26、小热休克蛋白ArHsp21蛋白以及过氧化物还原酶异构体在激活卵中特异表达。 活化卵孵化过程中不同发育时期的蛋白表达又呈现出不同的特点,分别在孵化后6h、12h、18h和24h的蛋白质组学图谱上检测到267、285、195和210个蛋白点。孵化后6h和12h休眠卵蛋白表达个数相对较多,与胚胎发育过程中的器官发生和剧烈的形态变化相适应;孵化后18h和24h休眠卵蛋白表达明显下降,部分蛋白的表达关闭,部分蛋白开始富集表达。 利用双向凝胶电泳技术分析了中华卤虫幼体受到急性硫酸铜刺激后的蛋白表达变化情况。通过图谱对比分析,检测到了5mM硫酸铜刺激24h后,卤虫幼体中14个差异表达的蛋白点。利用LC-ESI-MS/MS技术鉴定了其中的7个蛋白,其中3个蛋白上调表达,分别是热休克蛋白70(7.5倍), 肌动蛋白(2.3倍)和伴侣分子亚基1(3.0倍)。3个蛋白下调表达,分别是:精氨酸激酶(2.8倍), 延伸因子2 (2.0倍) 和富含甘氨酸蛋白(2.0倍)。硫酸铜刺激后特异表达的一个蛋白被鉴定为过氧化物还原酶(Peroxiredoxin,Prx)。根据质谱检测提供的蛋白肽段信息和其他生物过氧化物还原酶保守氨基酸序列设计简并引物,结合RACE技术,从中华卤虫幼体中克隆到了过氧化物还原酶基因,该基因的cDNA全长为756个碱基,其中开放阅读框为594个碱基,编码198个氨基酸,其蛋白理论分子量为22.0 kDa,理论等电点为6.98。多序列比对结果显示中华卤虫Prx基因的推导氨基酸序列与美国卤虫和中国对虾的同源性高达98%和94%。实时荧光定量PCR结果显示,硫酸铜刺激后,该基因在卤虫无节幼体中的转录水平明显升高,在24h达到正常水平的3.0倍。
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In order to improve the production and accurately estimate response to selection, divergent selection for growth in shell height was conducted in a cultured population of the Japanese scallop Patinopecten yessoensis. Applying the same selection intensity +/- 1.756 in upward and downward directions, three groups including two selected groups of Fast and Slow and one non-selected Control group were created, which were reared under the same environmental conditions at any stage. Differences always significantly existed among the three groups (P < 0.05), except for larvae at day 1 and at day 5, and in the order of Fast > Control > Slow. The average standardized response to selection (SR), realized heritability (h(R)2) and genetic gain (GG) was 0.473%, 0.269% and 7.85% for the Fast group and 0.381%, 0.217% and 6.60% for the Slow group respectively. Moreover, significant differences (P < 0.05) were detected between the fast and the slow lines in both SR and h(R)2, providing evidence for an asymmetric response in two directions. Performance in shell height is improved by 7.85% in the fast line after one generation selection, suggesting that mass selection for faster growth in a cultured population of the Japanese scallop is effective.
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1999~2002年的6~8月份,在青海门源地区收集了大鵟和雕鸮的吐弃块(pellets)和残留食物(food remains),带回实验室进行分检鉴定、研究分析。大鵟食物中共有736个猪物,其中高原鼢鼠28只、高原鼠兔139只、甘肃鼠兔142只、田鼠科动物422只、雀形目鸟类4只、香鼬1只;各猎物对大鵟食物的生物量贡献率分别为14.26%、40.79%、17.39%、26.99%、0.22%、0.35%。雕鸮食物中共有330个猎物,其中高原鼢鼠17只、高原鼠兔77只、甘肃鼠兔44只、田鼠科动物183只、雀形目鸟类2只、红脚鹬2只、高原兔5只;各猎物对雕鸮食物的生物量贡献率分别为11.83%、30.87%、7.36%、16.00%、0.15%、0.62%、33.17%。雕鸮的食物生态位宽度与大鵟的食物生态位宽度相近,食物生态位高度重叠,但是它们捕食同种猎物的比例显著不同。
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本文介绍了 OPC技术和 FF( Foundation Fieldbus)基金会现场总线 ,及 OPC技术在现场总线控制系统 ( FCS)中的应用和实现
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互连网上电子商务的蓬勃发展为企业提供了巨大商机,但风险也是巨大的。同时,网上信息爆炸也需要一种使用的方法对信息进行分析、整理、提取,为下一步的决策提供坚实的基础。本文在总结不同风险分析方法的基础上,提出了一种完整的方法,为网上商务的风险分析和决策提供了一种实用的解决方案。
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介绍了OPC服务器中用于与硬件设备I/O交互的动态链接库的开发方法,并着重讨论了数据类型转换问题。
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Various carbonaceous deposits are formed during the course of methane dehydro-aromatization (MDA) under non-oxidative conditions on Mo/MCM-22 catalysts. These carbon species were investigated by various temperature-programmed techniques such as TPH and TPCO2, combining with TPO and TGA results in order to reveal their chemical nature and determine their amounts. The TPO profiles recorded from coked Mo/MCM-22 catalysts show two temperature peaks: one at about 756 K and the other at about 876 K. The coke amounts related to these two peaks were determined on the basis of the corresponding corrected and deconvoluted TPO profiles, combining with the TGA profiles concerned.
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A monolithic silica based strong cation-exchange stationary phase was successfully prepared for capillary electrochromatography. The monolithic silica matrix from a sol-gel process was chemically modified by treatment with 3-mercaptopropyltrimethoxysilane followed by a chemical oxidation procedure to produce the desired function. The strong cation-exchange stationary phase was characterized by its substantial and stable electroosmotic flow (EOF), and it was observed that the EOF value of the prepared column remained almost unchanged at different buffer pH values and slowly decreased with increasing phosphate concentration in the mobile phase. The monolithic silica column with strong cation-exchange stationary phase has been successfully employed in the electrochromatographic separation of beta-blockers and alkaloids extracted from traditional Chinese medicines (TCMs). The column efficiencies for the tested beta-blockers varied from 210,000 to 340,000 plates/m. A peak compression effect was observed for atenolol with the mobile phase having a low phosphate concentration.
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Williams, G., Provocation and Killing with Compassion (2001) 65 (2) Journal of Criminal Law 149;
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http://www.archive.org/details/ponziglionescho00gravrich
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A focus on ecosystem services (ES) is seen as a means for improving decisionmaking. In the research to date, the valuation of the material contributions of ecosystems to human well-being has been emphasized, with less attention to important cultural ES and nonmaterial values. This gap persists because there is no commonly accepted framework for eliciting less tangible values, characterizing their changes, and including them alongside other services in decisionmaking. Here, we develop such a framework for ES research and practice, addressing three challenges: (1) Nonmaterial values are ill suited to characterization using monetary methods; (2) it is difficult to unequivocally link particular changes in socioecological systems to particular changes in cultural benefits; and (3) cultural benefits are associated with many services, not just cultural ES. There is no magic bullet, but our framework may facilitate fuller and more socially acceptable integrations of ES information into planning and management. © 2012 by American Institute of Biological Sciences. All rights reserved.
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Governments across the globe have squandered treasure and imprisoned millions of their own citizens by criminalising the use and sale of recreational drugs. But use of these drugs has remained relatively constant, and the primary victims are the users themselves. Meanwhile, antimicrobial drugs that once had the power to cure infections are losing their ability to do so, compromising the health of people around the world. The thesis of this essay is that policymakers should stop wasting resources trying to fight an unwinnable and morally dubious war against recreational drug users, and start shifting their attention to the serious threat posed by our collective misuse of antibiotics.
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Researchers currently debate whether new semantic knowledge can be learned and retrieved despite extensive damage to medial temporal lobe (MTL) structures. The authors explored whether H. M., a patient with amnesia, could acquire new semantic information in the context of his lifelong hobby of solving crossword puzzles. First, H. M. was tested on a series of word-skills tests believed important in solving crosswords. He also completed 3 new crosswords: 1 puzzle testing pre-1953 knowledge, another testing post-1953 knowledge, and another combining the 2 by giving postoperative semantic clues for preoperative answers. From the results, the authors concluded that H. M. can acquire new semantic knowledge, at least temporarily, when he can anchor it to mental representations established preoperatively.