991 resultados para ergosterol-5,8-peroxide


Relevância:

100.00% 100.00%

Publicador:

Resumo:

运用 18个有效的 10mer 寡核苷酸引物对浙江产车前 (Plantagoasiatica)的 8个种群基因组DNA进行了PCR扩增 ,共检测到 186个位点 ,其中多态位点 12 5个 ,占 6 8.70 % .应用Jaccard公式计算了 8个种群在 12 5个位点上的相似性 .以此为基础 ,应用主坐标排序 ,作出了 8个种群遗传分化的三维排序图 .结果表明 ,8个种群的遗传分化与地理位置、海拔高度有联系 .

Relevância:

100.00% 100.00%

Publicador:

Resumo:

首次报道了浙江省金华山 38科、77属 1 4 0种苔藓植物 .其中 ,苔类 1 4科 1 6属 2 0种 ,藓类 2 4科 61属1 2 0种 ;浙江省新记录种 30种 ,新记录属 7个 .该地区的苔藓植物以东亚、北温带和世界广布成分为主 ,分别占总种数的 4 0 .4 2 %、1 9.86%和 1 6.31 % ,热带成分的比例为 9.2 2 % .藓类植物中 ,主要的科为丛藓科 ( Potti-aceae)、羽藓科 ( Thuidiaceae)、青藓科 ( Brachytheciaceae)、真藓科 ( Bryaceae)和凤尾藓科 ( Fissidentaceae) ,真藓属 ( Bryum)、青藓属 ( Brachythecium)、凤尾藓属 ( Fissidens)、羽藓属 ( Thuidium)和走灯藓属 ( Plagiomnium)为5个主要属 .比较了金华山与中国其它 8个山地藓类区系的相似性 .

Relevância:

100.00% 100.00%

Publicador:

Resumo:

为了实现农业持续发展和保护生态环境,该文应用Penman-Monteith公式和GIS的空间分析功能,通过建立区域参考作物蒸散量的空间分布模型计算了中国东北地区自20世纪90年代以来参考作物蒸散量的时空变化特征。研究发现,20世纪90年代东北地区5~9月份日平均蒸散量呈逐年增大趋势,并以每年0.04mm的速度递增;其中5、6、7、8、9各月份绝大部分地区日均蒸散量年变化呈增加的趋势,东北平原年增长超过0.05mm,≥0.4mm蒸散地区年平均增长面积为248.73万hm2。5月份和8月份大部分地区日均蒸散量呈减少的趋势,6、7、9月份大部分地区日均蒸散量呈增加的趋势。5月和8月蒸散量的减少以及6月到9月蒸散量的增加都由东北(三江平原)向西南(辽河平原)迁移,并在空间范围上表现出一定的收缩趋势。日均蒸散量≥0.4mm蒸散地区的重心呈有规律的波动,5~9月份平均重心年际波动主要位于呼伦贝尔高原和西辽河平原两个地区,5、6、7、8、9月份重心的波动轨迹基本为由西北—东北—西南地区,空间上也逐渐由较集中变为较分散。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

香港地区每年均有一定数量的滑坡灾害发生,诱发滑坡灾害的主要因子是强降水,即暴雨。暴雨过程中,降水强度的时空分布存在一定差异性,这种降水强度的时空与滑坡灾害的时空分布存在一定的联系。以香港地区1992年5月8日暴雨为例,以30min为时间间隔,分析了暴雨中心时空变动与滑坡事件时空分布及出现频率之间的关系,发现空间上滑坡均出现在暴雨中心或暴雨中心的边沿地区;时间上滑坡事件出现在暴雨中心出现或上一阶段时间内;并且降水的强度与滑坡的出现频率也有一定关系。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

本书是《中国可持续发展总纲》第5卷。本书从总论和区域分论两个层次上全面阐述了我国土地资源利用历史、现状和存在的问题,从土地资源的高效持续利用及土地资源与其他资源相配合共同支撑经济、社会可持续发展的角度,探讨了土地资源利用与可持续发展的关系,提出了土地资源可持续利用若干战略对策。全书分上、下两篇。上篇是中国土地资源与可持续发展总论,包括中国土地资源与可持续发展概论,耕地、园地、林地、草地、湿地(水域)、交通用地、居民点及工矿用地、未利用土地等土地资源8个一级类的利用与持续发展分论等13章。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

本发明涉及一种滇池金线鲃的人工受精及孵化方法,属鱼产品养殖技术领域。该方法由干法受精和人工孵化组成。对性成熟金线鲃亲鱼用马来酸地欧酮按每公斤体重1mg和促黄体素释放激素A2按每公斤体重1μg进行肌肉注射,注射24小时后分别将卵、精成熟的雌、雄滇池金线鲃的卵子和精子从其腹部轻轻压挤出,在器皿中用鸡毛轻轻搅拌30秒,再加入清水搅拌20秒,再经三次清水清洗干净,然后均匀泼洒粘附在已经清洗消毒杀菌处理的棕片上,放入5ppm霉菌净溶液中浸泡消毒15分钟,取出放入20m2 或50m2的孵化池中进行孵化,在水温18~20℃,pH7.5~8.0的条件下,用氧气泵增氧进行孵化,经150小时后完成孵化。本发明具有成本低、操作简便,能投入产业化、集约化生产,受精率及孵化率高的优点。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

已有的研究表明,眶额叶在解剖上与现在已知的药物滥用相关的脑区是紧密联系在一起的。例如,眶额叶在药物滥用和强迫性重复行为中起作用,且随着脑成像技术的应用,越来越多的证据表明眶额叶参与了药物滥用。但是我们并不了解在阿片给药和戒断期间眶额叶脑区活动是如何变化的。因此,我们在实验中采用了Mn2+增强的核磁共振成像(Manganese-enhanced magnetic resonance imaging,MEMRI,4.7T)技术和脑电(EEG)记录的方法,以研究大鼠眶额叶在给与阿片类药物(盐酸吗啡)以及戒断过程中的动态变化。 MEMRI是一种近年才发展起来的新型技术。研究表明,Mn2+是Ca2+的类似物,可以通过Ca2+通道进入兴奋性的神经元里面并结合到胞内的蛋白质和核酸上的Ca2+和Mg2+结合位点上 (MILDVAN and COHN, 1963; EISINGER et al., 1965)。另外,Mn2+的顺磁性也为它成为核磁共振成像的造影剂提供了前提条件。可是成功应用MEMRI的前提就是要在适当的时间把合适剂量的Mn2+传递到靶点上。因此,Mn2+在注射到靶点后,是否能够在有效的时间内反映大脑活动的变化就成为一个非常重要并且在技术上较为棘手的问题。在给实验大鼠脑区微量注射Mn2+(80mMol/L,200nl)的同时,通过微量注射兴奋性神经递质谷氨酸(Glu 0.5mM/L)或抑制性递质γ-aminobutyric acid(GABA 0.5M/L)以改变靶点神经元兴奋性的方法,检测Mn2+能否反映脑区的活动变化。另外,我们随机选取实验动物,分别在注射Mn2+ 3小时、5小时和8小时后对三组大鼠(n=5)进行10%福尔马林灌流,并且通过观察大鼠眶额叶脑区Mn2+强度的变化来研究最佳的灌流时间。我们的实验结果表明,Mn2++Glu组的右侧脑区/左侧脑区的Mn2+亮度比Mn2+空白对照组增加了20%(p=0.016, student t-test, *p <0.05),也远大于Mn2++GABA组(p=0.047, *p<0.05)。结果表明,当神经元被兴奋的时候,较多的Mn2+可以通过Ca2+通道进入兴奋的神经元内,使得Mn2+的成像亮度增加。由于Mn2+成像亮度的增加可以反映神经元的兴奋活动,因此可以显示出靶点区的脑活动。另外,在研究灌流时间对Mn2+亮度影响的实验中发现,注射Mn2+ 5小时后灌流得到的信噪比分别比注射Mn2+3小时(p=0.055)和8小时(p=0.004,*p<0.05)高出24%和32%。总之,我们采用微量注射Mn2+(80mM/L,200nl)后5小时用10%福尔马林心脏灌流的方法获得了较好的结果。另外在试验中我们首先观测了大鼠吗啡戒断后的行为学指标和检测大鼠戒断后条件化位置偏好的程度。实验结果表明大鼠可以建立非常明显的条件化位置偏好,但在湿狗抖等行为学指标上无明显症状。这说明大鼠对于吗啡(10mg/kg, 一天两次,持续12天)形成了明显的心理依赖而无明显的生理依赖。此外,MEMRI的结果表明,在吗啡给药的第1天和第6天,大鼠眶额叶的Mn2+强度与空白对照组相比有显著的降低( one-way ANOVA, Post Hoc Dunnett’s C Tests), F (6,28)=7.242, P<0.001);而在戒断第3天又恢复到正常水平,在戒断第5天和第7天Mn2+强度跟空白对照组相比没有显著性差别(one-way ANOVA, *p<0.05)。脑电(EEG)的结果表明,急性吗啡诱导的gamma波段的EEG显著降低(Two-way ANOVA, F(1,10)=13.626,p=0.006)。然而在戒断第1天gamma波段的EEG与空白对照组相比是增加的。在戒断第3天和戒断第5天,gamma波段的EEG与空白对照组相比也有显著性增强。以上研究结果表明:大鼠眶额叶脑区的动态变化与整个吗啡给药和戒断过程是密切相关的;此外,MEMRI在探讨药物滥用以及成瘾等机制上有很大的应用前景。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

A series of sulfonated polyimides (SPIs) containing pyridine ring in the polymer backbone were synthesized by the polycondensation of 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTDA), 5-(2,6-bis(4-arninophenyl)pyridin-4-yl)-2-methoxy benzene sulfonic acid (SDAM), and 4,4'-diaminodiphenyl ether (ODA). Flexible, transparent, and tough membranes were obtained. Property study revealed that all the membranes displayed high thermal stability with the desulfonation and decomposition temperature higher than 290 and 540 degrees C, respectively, as well as good mechanical property with Young's modulus larger than 1.0 GPa, maximum strength (MS) on a scale of 60-80 MPa, and elongation at break (EB) ranged from 41.79 to 75.17%.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

A novel sulfonated tetraamine, di(triethylammonium)-4,4'-bis(3,4-diaminophenoxy)biphenyl-3,3'-disulfonate (BAPBDS), was successfully synthesized by nucleophilic aromatic substitution of 4,4'-dihydroxybiphenyl with 5-chloro-2-nitroaniline, followed by sulfonation and reduction. A high-temperature polycondensation of sulfonated tetraamine, non-sulfonated tetraamine (4,4 -bis(3,4-aminophenoxy)biphenyl) and 1,4,5,8-naphthalenetetracarboxylic dianhydride (a) or 4,4'-binaphthyl-1,1',8,8'-tetracarboxylic dianydride (b) gave the poly[bis(benzimidazobenzisoquinolinones)] ionomers SPBIBI-a(x) or SPBIBI-b(x), where x refers to the molar percentage of the sulfonated tetraamine monomer. Flexible and tough membranes of high mechanical strength were obtained by solution casting and the electrolyte properties of the polymers were intensively investigated. The ionomer membranes displayed excellent dimensional and hydrolytic stabilities.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Synthetic routes to aluminium ethyl complexes supported by chiral tetradentate phenoxyamine (salan-type) ligands [Al(OC6H2(R-6-R-4)CH2)(2){CH3N(C6H10)NCH3}-C2H5] 7: R = H ; 5, 8: R = Cl; 6, 9: R = CH3) are reported. Enantiornerically pure salan ligands 1-3 with (R,R) configurations at their cyclohexane rings afforded the complexes 4, 5, and 6 as mixtures of two diastereoisomers (a and b). Each diastereoisomer a was, as determined by X-ray analysis, monomeric with a five-coordinated aluminium central core in the solid state, adopting a cis-(O,O) and cis-(Me,Me) ligand geometry. From the results of variable-temperature (VT) H-1 NMR in the temperature range of 220-335 K, H-1-H-1 NOESY at 220 K, and diffusion-ordered spectroscopy (DOSY), it is concluded that each diastereoisomer b is also monomeric with a five-coordinated aluminium central core.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

An oxygen carrier was prepared by encapsulating carbonylated hemoglobin (CO-Hb) molecules into polypeptide vesicles made from poly(L-lysine)-block-poly(L-phenylalanine) (PLL-b-PPA) diblock copolymers in aqueous medium at pH 5.8. The encapsulation was confirmed by confocal laser scanning microscopy (CLSM). The morphology and size of the Vesicles were studied by field-emission scanning electron microscopy (ESEM). They had a spherical shape with it mean diameter of about 4 to 5 mu m. The encapsulation efficiency of hemoglobin was 40 wt %, and the hemoglobin content in the vesicles was 32 wt %. The CO-Hb encapsulated in the PLL-b-PPA vesicles was more stable than free CO-Hb under ambient conditions, In the presence of a O-2 atmosphere, the CO-Hb in the vesicle could be converted into oxygen-binding hemoglobin (O-2-Hb) under irradiation of visible light for 2 h. Therefore, the CO-Hb/PLL-b-PPA vesicles are expected to be used its red blood cell substitutes.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

A novel wholly aromatic diamine, 2,2 '-bis(3-sulfobenzoyl)benzidine (2,2 '-BSBB), was successfully prepared by the reaction of 2,2 '-dibenzoylbenzidine (2,2 '-DBB) with fuming sulfuric acid. Copolymerization of 1,4,5,8-naphathlenetetracarboxylic dianhydride with 2,2 '-BSBB and 2,2 '-DBB generated a series of rigid-rod sulfonated polyimides. The synthesized copolymers with the -SO3H group on the side chain of polymers possessed high molecular weights revealed by their high viscosity and the formation of tough and flexible membranes. The copolymer membranes exhibited excellent oxidative stability and mechanical properties due to their fully aromatic structure extending through the backbone and pendent groups. They displayed clear anisotropic membrane swelling in water with negligibly small dimensional changes in the plane direction of the membrane. The proton conductivities of copolymer membranes increased with increasing IEC and temperature, reaching value above 1.25 x 10(-1) S/cm at 20 degrees C, which is higher than that of Nafion (R) 117 at the same measurement condition. They displayed reasonably high proton conductivity due to the higher acidity of benzoyl sulfonic acid group, the larger interchain spacing, which is available for water to occupy, taking their lower water uptake (WU) into account. Consequently, these materials proved to be promising as proton exchange membrane.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

A series of novel oxidation and water stable sulfonated polyimides (SPIs) were synthesized from 4,4'-binaphthyl-1,1',8,8'-tetracarboxylic dianhydride (BTDA), and wholly aromatic diamine 2,2'-bis(3-sulfobenzoyl) benzidine (2,2'-BSBB) for proton exchange membrane fuel cells. These polyimides could be cast into flexible and tough membranes from m-cresol solutions. The copolymer membranes exhibited excellent oxidative stability and mechanical properties due to their fully aromatic structure extending through the backbone and pendant groups. Moreover, all BTDA-based SPI membranes exhibited much better water stability than those based on the conventional 1,4,5,8-naphthalenecarboxylic dianhydride. The improved water stability of BTDA-based polyimides was attributed to its unique binaphthalimide structure. The SPI membranes with ion exchange capacity (IEC) of 1.36-1.90 mequiv g(-1) had proton conductivity in the range of 0.41 x 10(-1) to 1. 12 x 10(-1) S cm(-1) at 20 degrees C. The membrane with IEC value of 1.90 mequiv g(-1) displayed reasonably higher proton conductivity than Nafion((R)) 117 (0.9 x 10(-1) S cm(-1)) under the same test condition and the high conductivity of 0.184 S cm(-1) was obtained at 80 degrees C. Microscopic analyses revealed that well-dispersed hydrophilic domains contribute to better proton conducting properties. These results showed that the synthesized materials might have the potential to be applied as the proton exchange membranes for PEMFCs.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

A series of sulfonated polymides containing benzimidazole groups were synthesized using 4,4'-binaphthyl-1,1',8,8'-tetracarboxylic dianhydride (BTDA), 4,4'-diaminodiphenyl ether-2,2'-disulfonic acid (ODADS) as the sulfonated diamine, and 2-(3',5-diaminophenyl)benzimidazole (a) or 6,4'-diamino-2-phenylbenzimidazole (b) as the nonsulfortated diamine. The electrolyte properties of the synthesized polyimides Ia-x, Ib-x, x refers to molar percentage of the sulfonated diamine) were investigated and compared with those of polyimides (Ic-x) from BTDA, ODADS, and m-phenylenediamine (c). All synthesized polyimides possessed high molecular weights revealed by their high viscosity, and formation of tough and flexible membranes. Polyintides with benzimidazole groups exhibited much better swelling capacity than those without benzimiclazole groups. This was attributed to the strong interchain interaction through basic benzimidazole functions and sulfonic acid groups. The sulfortated polyimides that are incorporated with 1, 1',8,8'-binaphthalimide exhibited better hydrolytic stability than that with 1,4,5,8-naphthalimide. Polyimide membranes with good water stability as well as high proton conductivity were developed. Polyimide membrane (Ia - 90), for example, did not lose mechanical properties after being soaked in boiling water for tOOO h, while its proton conductivity was still at a high level (compared to that of Nafion 117).

Relevância:

100.00% 100.00%

Publicador:

Resumo:

简单介绍了对测量值中异常数据进行判别与剔除的三种统计判别方法——3σ准则、格鲁布斯准则和Q检验方法的基本原理,并以高分子科学实验中的两个实例为代表,应用Visual Basic for Applica-tions(VBA)编写的程序模块,对测量值中异常数据的判别与剔除进行了详细讨论。