671 resultados para Kön
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盐角草(Salicornia europaea L.)属藜科盐角草属(Salicornia),是迄今已报道过的最为耐盐的真盐生植物之一。跟与其同属的海蓬子(Salicornia bigelovvi Torr.)相比, 它的分布更为广泛。它的种子含油丰富,因此具有发展为油料作物的潜力。此外,它也可以作为蔬菜和饲料。盐角草的组织培养工作为未来的转化研究和胁迫相关基因功能分析提供了有力的工具。本工作中,通过器官发生途径,建立了盐角草的体外再生体系。以完整的成熟种子为起始培养材料,在添TDZ 0.1 mg/L与NAA 1 mg/L的MS培养基上,暗培养三周后在下胚轴处形成愈伤组织,形成愈伤的平均频率为99%。愈伤组织在含TDZ 0.1 mg/L与NAA 1 mg/L的培养基上培养3-4周后分化出芽,分化频率约26.7%。采用2,4-D短时处理法结合添加NaCl,经过6-8周的培养获得了丛生芽,提高了再生频率。分化芽3周后转入含IBA 0.5 mg/L、KN 0.1 mg/L与0.05%活性炭的1/2 MS培养基,3周后生根形成完整植株。同时,本研究也进行了从直接不定芽途径建立盐角草再生体系的试验,但未获成功。 此外,本工作借鉴拟南芥的floral-dip转化法,对建立盐角草floral-dip转化系统进行了尝试。
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Estimates of length-weight relationship in Otolithes cuvieri justify separate equations for males (log W =-5.0100+3.1365 log L) and females (log W =-5.2000+3.1006 log L). Relative condition factor "Kn" was found to be 0.877-1.946 in males and 0.879-1.328 in females. High "Kn" values during March to September at 180-220 mm TL in either sexes are indicative of the maturation of gonads. Separate equations for length-weight relationship are also justified for males (log W = -5.1126 + 3.0690 log L) and females (log W = -5.6400 + 3.3070 log L) of Johnius elongatus . "Kn" values were found to be 0.924-1.894 for males and 0.894-1.087 for females. High "Kn" values during January-May and August-September at 130 mm TL onward are indicative of gonadal maturation.
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The study deals with the length-weight relationship and relative condition factor (Kn) of mahseer, Tor putitora reared for 150 days in ponds. The logarithmic form of equation for the relationship was found to be logW = -1.727+2.875logL or W=O.Ol875U·875 • The graphical presentation of the parabolic and logarithmic forms showed respectively the curvilinear and linear relationships between length and weight of the fish. The mean value (±sd) of relative condition factor was found to be 0.95±0.12. The exponential value 'b' was found to be 2.96 and the coefficient of correlation 'r' was 0.965, which showed strong and highly correlated relationships between length and weight of the fish.
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To obtain a more complete understanding of the evolutionary history of the leaf-eating monkeys we have examined the mitochondrial genome sequence of two African and six Asian colobines. Although taxonomists have proposed grouping the "odd-nosed" colobines
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Eleven polymorphic microsatellite loci were characterized for the endangered conifer Taxus yunnanensis. Eight loci were isolated through SSR-anchored PCR, one locus was developed by cross-species amplification tests, while the last two loci were obtained
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The length-weight relationship of Daysciaena albida and Gerres filamentosus were calculated separately for indeterminants, mature males and mature females. The logarithmic regression equation obtained for D. albida - males: log w = -1.5055 + 2.8618 log l; females: log w = -0.9260 + 2.4089 log l; indeterminants: log w = -l.7188 + 3.0616 log l. The regression co-efficients between males and females, males and in determinants and female and in determinants showed significant differences. In G. filamentosus the relationship can be expressed as males: log w = -1.3224 + 2.8740 log 1; females: log w = -1.2874 + 2.8381 log l; indeterminants: log w = -0.8167 + 2.2558 log l. The difference in regression co-efficients between male and female are insignificant at 5% level whereas significant differences were observed between males and indeterminants and females and indeterminants. The relative condition factor (Kn) was calculated for the above two species. In D. albida the reasons for the fluctuations of Kn values can be attributed to both spawning cycle as well as feeding intensity whereas in G. filamentosus it synchronies mainly with spawning cycle.
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采用复合垂直流人工湿地处理武汉东湖污染水的中试结果表明 ,出水中NH+ 4-N、NO- 2 -N和凯氏氮 (KN)浓度均显著降低 ,而NO- 3-N含量有所上升 ;系统最佳运行水力负荷为 80 0mm/d ,超过此负荷后系统净化效果随负荷增加而下降 ;在东湖现有的污染负荷下 ,处理系统仍呈现出继续承载污染量的潜力 ;就基质中KN的分布而言 ,水平方向为下行流池含量高于上行流池 ,垂直方向为上层 >中层 >下层 ,而在植物体内的分布则为叶片中含量最高。
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研究了在间歇式进水条件下 ,复合构建湿地系统对氮的去除效果 ,阐述了温度、溶氧、pH等理化因子变化的原因。实验初期 ,系统尚处于不稳定时期 ,对N的去除不够理想。随着系统运转逐步步入稳定状态 ,对KN、NH+ 4 N、NO-2 N有明显的去除效果 ,平均去除率分别为 5 0 %、6 6 %和 71%。硝化 -反硝化作用是氨氮去除的主要途径。从总体上看 ,有植物系统中硝态氮的出水含量较对照系统高 ,说明间歇式进水以及植物的存在都有利于硝化作用的发生。实验发现 ,复合构建湿地在冬季仍能较好地改善水质 ,是一种
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阐述了垂直流人工湿地小试系统的设计 ,并测试其冬季污水净化效果 .垂直流人工湿地由下行流和上行流方式的两池组成 .对受污染地面水体中的CODCr、BOD5和TSS的去除率分别为 5 3.6 %、78.7%和 80 .2 % .对细菌、总大肠菌、粪大肠菌和藻类的平均去除率分别达 99.4%、85 .9%、89.7%和 97.7% .对KN、NH+ 4 N和TP的平均去除率分别为 39.2 %、16 .5 %和 2 5 .8% .各系统对污染物的去除作用无明显差异 .系统出水NO-3 N浓度高于进水 ,而有植
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利用平皿计数法和其他传统方法,研究了复合垂直流构建湿地基质微生物数量的季节变化以及它们与污水净化效果的相关性.结果表明,不同月份复合垂直流构建湿地基质中的微生物数量也不相同;构建湿地净化污水的过程中,下行流池发挥了主要作用;构建湿地基质中微生物数量与污水中的KN以及CODCr的去除率存在显著相关性,说明微生物的活动是它们去除的主要途径;构建湿地基质中的微生物数量与TSS以及TP的去除率没有明显的相关性,这说明TSS和TP的去除有其他途径.本研究为进一步利用构建湿地处理污水提供了依据.
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Boron nitride nanotubes (BNNTs) are considered as a promising cold electron emission material owing to their negative electron affinity. BNNT field emitters show excellent oxidation endurance after high temperature thermal annealing of 600 °C in air ambient. There is no damage to the BNNTs after thermal annealing at a temperature of 600 °C and also no degradation of field emission properties. The thermally annealed BNNTs exhibit a high maximum emission current density of 8.39mA/cm2 and show very robust emission stability. The BNNTs can be a promising emitter material for field emission devices under harsh oxygen environments. © 2014 AIP Publishing LLC.
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尼龙1010是我国特有的工程塑料。但对它的结构与性能的基础研究并不多见。迄今为止,许多聚酰胺的晶胞参数已被测定,并比较准确地计算出它们的结晶密度ρ_c。可是,尚未见到过有关尼龙1010的ρ_c的报道。此外,结晶高聚物的平衡熔融温度T°_m和平衡熔融热ΔH°_m是非常重要的热力学参数,尤其是后者更是用量热法计算结晶度的基准。早在50年代,Flory等对它的T°_m和ΔH°_m进行了许多研究,由于受当时历史条件限制,这些数值的准确性不高,不能当作平衡状态的数值。尼龙1010经γ-射线辐照后,有可能提高它的使用温度,扩大它的应用范围和领域。但至今未见到过大剂量下γ-辐照尼龙1010及其添加强化交联剂BMI的γ辐照产物的热学性能和结晶过程的研究。随着科学技术的发展,目前迫切需要准确的尼龙1010的ρ_c、T°_m、ΔH°_m的数值,以及大剂量下γ-辐照产物的热学性能和结晶过程的详细研究,以便更合理地开发和利用这一材料为四化建设服务。本文用DSC差示扫描量热仪、红外光谱仪、广角X-射线衍射仪以及TMS热机械仪等研究手段,准确地测定了尼龙1010的平衡热力学参数,并对尼龙1010及其添加强化交联剂BMI的γ-辐照产物的热学性能和结晶过程进行了详细的研究。用红外吸光度-密度外推法求得尼龙1010的ρ_a(非晶密度)= 1.003 ρ_c = 1.098g/cm~3。1.098g/cm~3与用X-射线衍射法求得的1.135g/cm~3比较,认为后者更为合理。用介稳态结晶试样的ΔH_m-(V-bar)_(sp)的线性关系,求得尼龙1010的平衡熔融热。ΔH°_m = 244.0J/g。企图用常用的Hoffman Tm-Tc外推法来确定尼龙1010的平衡熔融温度T°_m,但未能成功,并指出其升温过程中重结晶异常迅速是此法行不通的主要原因。用Kamide提出的双重外推法成功地求得尼龙1010的平衡熔融温度:T°_m = 487 K = 214 ℃通过详细地研究尼龙1010及其添加强化并联剂BMI的γ辐照产物的热学性能,发现强化交联剂BMI的加入,使尼龙1010大分子的交联更容易,但也使得空间网络较松散;同时γ辐照尼龙1010在再次等速升温过程中出现冷结晶峰是辐照产物中存在可结晶部分、交联网络阻碍可结晶部分结晶两者共同作用的结果。交联网络使可结晶部分在降温过程中来不及结晶,当再次升温到玻璃化转变温度以上时,链段冻结被解除,可结晶的分子链段进行有序排列而结晶,导致冷结晶峰的出现。冷结晶峰的强度和位置与辐照产物中可结晶部分的多少、交联网络的大小即相邻交联点之间的分子量Mc的大小、交联网络的松散程度以及试样的热历史都有关。选择适当的等温结晶温度,用DSC-2C型差示扫描量热仪研究了尼龙1010及其γ-辐照产物和添加强化交联剂BMI的γ-辐照产物的等温结晶过程。用DSC-2C 3600 TADS计算机自带的部分面积程序进行动力学数据处理。通过仔细的等温结晶动力学研究,发现γ辐照尼龙10104 Avrami指数n几乎不受辐照剂量R和强化交联剂BMI的影响,且一般为3.75,这说明尼龙1010及其γ辐照产物的结晶过程接近于均相三维成核。随着辐照剂量R和强化交联剂BMI含量的增大,折迭链表面自由能σe值增大,σe值的分布可能变宽,σe值的这种变化可以归因于辐照剂量R和强化交联剂BMI的含量增大时,交联网络增多,交联密度增大,Mc值的分布变宽,链尾和小链圈的数目增多,活动性减小,同时链尾也增长,结果导致σe(链尾、链圈)增大,从而σe值变大,σe值的分布可能变宽。σe值的这种变化也正是过冷度增大、拖尾现象严重、总的动力学速率常数Kn和结晶速率t_(0.5)~(-1)变小的总根源。由此可见,对于分子量不同或分子结构有差别的同一种结晶高聚物来说,σe值可以作为衡量结晶能力大小的定量标准。
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经验(experience)或突触活动依赖的突触信息传递效能的增强(LTP)或抑制(LTD)被称为突触可塑性(synaPticplasticity),是公认的学习和记忆的细胞分子学基础。突触可塑性的方向是突触信息传递效能的增强或降低;突触可塑性的程度是突触信息传递的效能增加量或降低量。突触活动历史可影响随后突触可塑性的方向或程度。这种突触可塑性的可塑性被称为高级可塑性(MetaP1asticity)。最明显的高级可塑性现象是发生在突触效能没有改变的情况下。经验或者突触活动可以同时诱导出突触可塑性和高级可塑性。除非知道突触活动的历史,否则很难预测突触可塑性的大小和方向。高级可塑性简单地讲就是过去的神经信息留下痕迹会对神经信息的加工处理产生持续性影响。目前高级可塑性的机理并不完全清楚。采用全细胞电压钳记录方法,在3周龄wistar大鼠海马脑片中,同时记录schaffer侧枝纤维一以1处兴奋性突触后膜电流(evokedEPsC)和自发性微小兴奋性突触后膜"电流(mEPSC)。结果显示,mEPSC和低频刺激诱导的长时程抑制(Long一TermDePre55ion,LTD)之间呈负相关,mEPsc的频率或幅值越小,诱导出的LTD幅度越大;应激和低钙溶液处理在降低记PsC的频率和幅值的同时并没有明显改变随后LTD的诱导幅,但是这两者负相关性依然存。相关系数在应激条件下有增加,在低钙溶液中有降低。以上结果提示,mPEsc的频率或幅值可能指示了过去的突触活动或经验产牛的高幼可朔件_田、冲稀恻了喃层的,:。、云导的幅度。C鹉子妙触可黔和高级可黔中起着关键作。作为一种非选择性阳离子通道,van11101drec即tortyPel(VR1或TRPVI)在脑区中广泛表达,尤其在海马高表达。内源性配体可以激活该受体通道。但目前并不清楚vRI在海马突触可塑性当中的作用。我们发现VRI激动剂辣椒素不影响脑片中海马以1区基础突触传递,但是它阻断低频诱导(LFS,3Hz)的LTD,增强高频诱导(HFs,20OHz)的长时程增强(Long一TerlnPotetiantion,LTP)。也就是vRI激活改变了突触可塑性的方向,是一种经典的高级可塑性现象。正常情况下50Hz不能诱导出LTP,而加入辣椒素后易化了LTP的诱导。因此LTP诱导的闽值降低。辣椒素激动剂对突触可塑性或高级可塑性的效应不依赖协。A受体而依赖于H型钙调蛋白激酶(CaMKII)的调控。因为场。A受体电流和它的电流一电压曲线不受此激动剂影响,但CaMKII抑制剂KN-93或者VRI拮抗剂capsazepine却阻断了辣椒素的这种效应。这些发现,显示VRI可以调控海马以1区的高级突触可塑性,可能参与某些类型的学习和记忆。
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Quantum well disordering of GaAs/AlGaAs multiple quantum well(MQW) has been accomplished with only plasma enhanced chemical vapor deposited (PECVD) SiN cap layer growth. The amount of blue shift increases with SiN growing time. This result has been explained by the vacancy indiffusion during PECVD SiN growth. Rapid thermal annealing (RTA) of the sample after SiN cap layer growth at 850 degrees C for 35 s caused a larger amount of blue shift than those obtained without RTA. By considering the model of Al diffusion from AlGaAs barrier into GaAs QWs together with the result from photoluminescence (PL) measurement, Al diffusion coefficients were calculated. The Al diffusion coefficient due to PECVD SiN was estimated at about 3 x10(-17) cm(2)/s. It was possible to extract the effect of RTA on the QW disordering, which showed that the amount of the blue shift and the Al diffusion coefficient due only to RTA increases with SiN cap layer thickness as reported by Chi et al.(10))