983 resultados para Mechitar, 1676-1749.
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冷杉属是松科中的第二大属,在北半球有着广泛的分布区,从温带的高纬度地带到亚热带(偶达热带地区)的山地,呈间断不连续的分布。虽然一些学者曾对冷杉属进行过大量的分类学和系统学研究,但该属复杂的变异式样至今仍困扰着植物系统学家们。本论文是在腊叶标本和野外实地调查的基础上,从形态学、解剖学、分子系统学和植物地理学等方面进行分类学和系统发育的分析研究。现得到以下初步结果。1.对冷杉属叶角质层内表面胞间凸缘的研究结果表明,可以分为4种类型: 1. 弯曲且发达的单凸缘;2直且发达的单凸缘;3不发达的单凸缘;4双桥型凸缘。分布于欧洲和亚洲的绝大部分种类都是弯曲且发达的单凸缘类型(日本一种除外),而分布于北美的种类则具有四种不同的类型。 2. 叶横切面的研究结果表明皮下层细胞的发育状况和树脂道的位置与大小在Sect. Balsamea中稳定,皮下层细胞的缺失和不发育、树脂道大且中生在该属中可能反映原始状态。 3. 本研究首次发现nrDNA ITS的长度在属下有较大的变异,变异幅度1700 bp-2500 bp,分析得出引起这一变异的主要原因是由于ITS1中有以GGCCACCCTAGTC为核心数目不等的重复序列的存在,并讨论了ITS长度的变异在冷杉属和松科系统演化中的意义。 4. nrDNA ITS的RFLP分析结果和5种冷杉的ITS序列分析结果(以Keteleeria davidiana为外类群)表明A. bracteata与Sect. Balsamea总是聚在一起,亲缘最近;A. kawakamii应属于Sect. Momi。 5. 地理分布和系统发育分析的研究结果表明,冷杉属的多样性中心在北美西南部、而种类分布最大多的地区为东亚、种群分化最强烈的地区为我国的横断山脉。根据冷杉属的系统发育、化石资料和现代冷杉属的地理分布格局,冷杉属可能起源于白垩纪的高纬度地带。 6. 结合ITS RFLP和ITS序列的分支分析结果以及某些形态特征和地理分布资料,重建属下分类系统,将冷杉属分为8组2亚组。探讨了各组间的亲缘关系,认为Sect. Balsamea是冷杉属中的原始类群,Sect. Balsamea是与Sect. Balsamea亲缘最近,形态上十分特化的类群。来自ITS的分析结果为摒属下亚属的划分和将A. kawakamii自Sect. Balsamea中移出,放入Sect. Momi中提供了强有力的证据。经过标本和文献考证,综合各方面的资料,本文对冷杉属进行了全面系统的分类学修订,包括44种17变种1亚种,系统排列如下: 组1. 树脂冷杉组Sect. 1. Balsamea Engelmann。该组包括8种4变种:Abies balsamea, A. lasiocarpa, A. sibirica, A. sachalinensis, A. fraseri, A. koreana, A. nephrolepis, A. veitchii, A. bracteata。 组3. 日本冷杉组Sect. 3. Momi Franco。 亚组1.日本冷杉亚组Subsect. 1. Firmae (Franco) Farjon et Rushforth。该亚组包括6种3变种:A.holophylla, A. homolepis, A. firma, A. beshanzuensis, A. chensiensis, A. pindrow, A. beshanzuensis var. ziyuanensis, A. chensiensis var. ernestii, A. chensiensis var. salouenensis。 亚组2. 鳞皮冷杉亚组Subsect. 2. Squamatae E. Murray。该亚组包括12种6变种:A squamata, A. delavayi, A. nukiangensis, A. recurvata, A. spectabilis, A. mariesii, A. kawakamii, A. forrestii, A. fargesii, A. fansipanensis, A. fanjingshanensis, A. yuanbaoshanensis, A. delavayi var. fabri, A. delavayi var. motuoensis, A. spectabilis var. densa, A. forrestii var. georgei, A. forrestii var. ferreana, A. fargesii var. faxoniana。 组4. 冷杉组Sect. 4. Abies。该组包括7种1变种1亚种:A. alba, A. cephalonica, A. nordmanniana, A. nebrodensis, A. cilicica, A. pinsapo, A. numidica, A. nordamanniana ssp. equitrojani, A. pinsapo var. marocana。 组5. 太平洋冷杉组成Sect. 5. Amabiles (Matzenko) Farjon et Rushforth。该组仅一种:A. amabilis。 组6. 高贵冷杉组Sect. 6. Nobilis Engelmann。该组有2种1变种:A. procera, A. magnifica, A. magnifica var. shastensis。 组7. 大冷杉组成Sect. 7. Grandes Engelmann, emend. Farjon et Rushforth。该组包括4种2变种:A. concolor, A. grandis, A. durangensis, A. guatemalensis, A. concolor var. lowiana, A. durangensis var. coahuilensis。 组8. 墨西哥冷杉组Sect. 8. Oiamel Franco, emend. Farjon et Rushforth。该组包括A. religiosa, A. vejarii, A. vejari var. mexicana, A. hickelii
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Experimental data have demonstrated that mushroom-shaped fibrils adhere much better to smooth substrates than punch-shaped fibrils. We present a model that suggests that detachment processes for such fibrils are controlled by defects in the contact area that are confined to its outer edge. Stress analysis of the adhered fibril, carried out for both punch and mushroom shapes with and without friction, suggests that defects near the edge of the adhesion area are much more damaging to the pull-off strength in the case of the punch than for the mushroom. The simulations show that the punch has a higher driving force for extension of small edge defects compared with the mushroom adhesion. The ratio of the pull-off force for the mushroom to that of the punch can be predicted from these simulations to be much greater than 20 in the friction-free case, similar to the experimental value. In the case of sticking friction, a ratio of 14 can be deduced. Our analysis also offers a possible explanation for the evolution of asymmetric mushroom shapes (spatulae) in the adhesion organ of geckos.
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长鳞红景天(Rhodiola gelida)属景天科红景天属,多年生草本。主要分布在我国新疆中部天山。在天山一号冰川观测试验站附近的高寒草甸上,从海拔3850m~4010m均有长鳞红景天分布。长鳞红景天是一种重要的药用植物,但目前尚未见到有关其遗传多样性方面的研究报道。本文利用相关序列扩增多态性(sequence-related amplified polymorphism,SRAP)分子标记技术,对新疆天山不同海拔高度3个长鳞红景天种群的遗传多样性,种群内及种群间的遗传变异进行研究,为有效保护和合理利用长鳞红景天物种资源提供理论依据。主要结果如下: (1)基于CTAB法,建立了适合长鳞红景天的DNA提取方法,获得的DNA经琼脂糖电泳和紫外分析仪检测,浓度和质量均较高。该法有利于去除长鳞红景天植物材料中多糖、多酚类等物质,获得的高质量基因组DNA能够满足后续的PCR实验要求。 (2)采用正交实验对影响长鳞红景天SRAP-PCR反应的4个主要因素(Taq酶用量、Mg2+浓度、dNTP浓度、引物浓度)进行优化试验,选出这4个因素的最佳水平组合,建立了长鳞红景天SRAP-PCR最佳反应体系。同时,根据最佳体系筛选出扩增稳定、多态性丰富的SRAP引物。通过梯度PCR确定引物的最佳退火温度,得到了适合长鳞红景天SRAP-PCR反应的最佳扩增程序。 (3)对20对SRAP引物的扩增结果进行统计分析显示:长鳞红景天物种水平的多态位点百分率(P)为96.00 %,Shannon信息指数(I)为0.4484、基因多样性指数(H)为0.2922,表现出较高的遗传多样性水平;在海拔梯度上,长鳞红景天各种群间的遗传多样性水平有一定差异,但没有呈现规律性的变化;AMOVA分子变异分析显示,在总遗传变异中24.76 % 的变异存在于种群间,75.24 % 的变异存在于种群内,种群间的基因分化系数(Gst)为0.1749,表明3个长鳞红景天种群的变异主要存在于种群内,但种群间也出现了一定程度的遗传分化;长鳞红景天3个种群间的基因流为2.3595,遗传距离平均值为0.0981(变化范围:0.0768 ~0.1196),遗传距离较近,说明海拔高度对长鳞红景天的地理隔离较小;相关性分析表明长鳞红景天种群的遗传多样性与各生态因子的相关性均不显著。
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An experiment of 120 days of culture was conducted in brackishwater earthen ponds having an area of 0.2ha each. The hatchery produced shrimp (Penaeus monodon) post larvae were stocked in the 40m² fine meshed nylon net nursery enclosures were fed with commercial pellet feed. After two weeks of nursing, juveniles were allowed to spread in cultural pond by opening the fence. Fingerlings of three different strain of tilapia were stocked as shrimp and Strain-1 all male (monosex) (T1), shrimp and Strain-2 all male (T2), shrimp and Strain-3 mixed sex population (T3) @ 20.000/ha and 10.000/ha, respectively and shrimp only (monoculture) (T4) @ 20.000/ha. The shrimp and fish were fed with farm made feed consisting of a mixture of fishmeal 29%, MOC 15%, rice bran 30%, soybean meal 16%, wheat flour 9% and vitamin premix 0.1%. The average final weight of shrimp was 24.9±1.13g, 23.41±3.26g and 26.67±1.89g that stocked with tilapia in treatments T1, T2, and T3 respectively. The final average weight of shrimp in monoculture (T4) was 27.41±0.76g, apparently higher but insignificant in treatments. The survival of shrimp was 42.17%, 32.38%, 39.45% and 61.98% in treatments T1 T2, T3 and T4 respectively. The production of shrimp in concurrent culture was 193.67, 154.26 and 210.41kg/ha in T1, T2 and T3, respectively, while in monoculture (T4) was 339.77 kg/ha. The growth and survival of tilapia among the treatments was insignificant. The growth of monosex tilapia ranged 225.29 and 291.31g and survival 62.77 and 72.20% in T1 and T2, respectively, in mixed sex was 193.0g and 83.20% (T3). The production of tilapia monosex strains was 1676.69kg/ha (Strain-2 all male) and 1668.98 kg/ha (Strain-1 all male) while that of Strain-3 mixed sex population was 1622.92 kg/ha.
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实地调查了香格里拉县小中甸水利枢纽工程周边评价区域内的两栖动物、爬行动物以及鱼类的生物多样性。项目评价区共有鱼类20种(其中17种为土著物种) , 两栖动物10种, 爬行动物11种。同时, 分析了工程建设将对其造成的影响, 并提出相关建议和保护措施。
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本发明经阴离子交换剂柱层析法分离纯化及快速蛋白纯化工作站程序再纯化,从我国特产尖吻蝮(Agkistrodon acutus)蛇毒中得到纯度在97%以上的尖吻蝮蛇毒凝血酶Ⅱ;经测定,该酶Ⅱ由A、B两个亚基(链)组成,其中,A亚基含有125个氨基酸,B亚基含有123个氨基酸;与现有蛇毒凝血酶(如Reptilase)相比,它是一个全新的新型酶止血剂。经药理、毒理、药代等研究表明,它是一个见效快,副作用小的、安全有效的新型止血剂。
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The effects of multiple scattering on acoustic manipulation of spherical particles using helicoidal Bessel-beams are discussed. A closed-form analytical solution is developed to calculate the acoustic radiation force resulting from a Bessel-beam on an acoustically reflective sphere, in the presence of an adjacent spherical particle, immersed in an unbounded fluid medium. The solution is based on the standard Fourier decomposition method and the effect of multi-scattering is taken into account using the addition theorem for spherical coordinates. Of particular interest here is the investigation of the effects of multiple scattering on the emergence of negative axial forces. To investigate the effects, the radiation force applied on the target particle resulting from a helicoidal Bessel-beam of different azimuthal indexes (m = 1 to 4), at different conical angles, is computed. Results are presented for soft and rigid spheres of various sizes, separated by a finite distance. Results have shown that the emergence of negative force regions is very sensitive to the level of cross-scattering between the particles. It has also been shown that in multiple scattering media, the negative axial force may occur at much smaller conical angles than previously reported for single particles, and that acoustic manipulation of soft spheres in such media may also become possible.
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在自然条件下,采用人工模拟水缸培养方法,研究了湖泊底泥不同Cu、Cd处理对沉水植物伊乐藻生长、叶绿素含量以及Cu、Cd吸收和积累的影响。结果表明,较低浓度Cu刺激伊乐藻的生长(生物量、叶绿素),高浓度抑制伊乐藻的生长;随着Cd处理浓度的增加,伊乐藻的生物量、叶绿素含量均一直降低,在底泥Cd含量为168.69mg·kg-1DW(含背景值)时,植株出现死亡。随着Cu处理浓度的增加,伊乐藻体内的Cu含量一直增加,在底泥Cu含量为414mg·kg-1DW(含背景值)时,根部、叶部的富集系数均达到最大(0.21和0
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利用聚丙烯酰氨凝胶电泳技术 ,对采自武汉沙湖螅状独缩虫自然种群的酯酶 (EST)、苹果酸脱氢酶 (MDH)、乳酸脱氢酶 (LDH)和酸性磷酸酶 (ACP)四种同工酶酶系进行了研究。实验表明 :EST同工酶酶系由六个基因座位(Est 1—Est 6 )控制 ,其中Est 1、Est 2、Est 3和Est 5为杂合基因座位 ,而Est 4和Est 6为纯合基因座位。螅状独缩虫物种中EST同工酶四级结构既有单体也有二聚体 ;MDH同工酶酶系由五个基因座位 (Mdh 1—Mdh 5 )控制 ,其中Mdh 2和M