995 resultados para 163-989A


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In order to observe the effect of salinity on disease resistance and white spot syndrome virus (WSSV) proliferation in Fenneropenaeus chinensis, shrimps with latent WSSV were subjected to two acute salinity changes from the original salinity of 22 ppt to 18 and 14 ppt in an hour, respectively. The total haemocyte count (THC) of the challenged group showed no evident change under salinity adjustments, but the phenoloxidase (PO) index declined significantly (P<0.05) corresponding to continuing acute salinity changes from the 24th to the 72nd hour. According to the WSSV load detected by quantitative real-time PCR method, it was found that WSSV carried by the challenged group and control group were significantly different (P<0.05); acute salinity change from 22 to 14 ppt led to the WSSV carried in the challenged group being significantly higher (P<0.05) than that of those surviving in 22 ppt, but salinity change from 22 to 18 ppt had no such effect. At the end of the 72-h experiment, the challenged group subjected to salinity change from 22 to 14 ppt had nearly 3 times the WSSV load as the control group with no salinity change. Therefore, salinity changes over a particular range could result in a decrease of immunocompetence and obvious WSSV proliferation in the shrimps, leading to white spot syndrome developing from a latent infection to an acute outbreak. (C) 2005 Elsevier B.V All rights reserved.

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Chitosan, carboxymethyl chitosan (CIVICS) and chitosan sulfates (CSS) with different molecular weight were modified by reacting with 4-hydroxyl-5-chloride-1,3-benzene-disulfo-chloride or 2-hydroxyl-5-chloride-1,3 -benzene-disulfo-chloride to give 12 kinds of new hydroxylbenzenesulfonailides derivatives of them. The preparation conditions of the derivatives were discussed in this paper, and their structures were characterized by FT-IR and C-13 NMR spectroscopy. The solubility of the derivatives was measured in the experiment. In addition, their antimicrobial activities against four bacteria and five crop-threatening pathogenic fungi were tested in the experiment. Besides, the rule and mechanism of their antibacterial activities were discussed in this paper. (C) 2009 Published by Elsevier B.V.

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CoWO4 nano-particles were successfully synthesized at a low temperature of 270 degrees C by a molten salt method, and effects of such processing parameters as holding time and salt quantity on the crystallization and development Of CoWO4 crystallites were initially studied. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM). and photoluminescent spectra techniques (PL), respectively. Experimental results showed that the well-crystallized CoWO4 nano-particles with ca. 45 nm in diameter could be obtained at 270 degrees C for a holding time of 8 h with 6:1 mass ratio of the salt to CoWO4 precursor, and XRD analysis evidenced that the as-prepared sample was a pure monoclinic phase Of CoWO4 with wolframite structure. Their PL spectra revealed that the CoWO4 nano-particles displayed a very strong PL peak at 453 nm with the excitation wavelength of 230 nm, and PL properties of CoWO4 crystallites relied on their crystalline state, especially on their particle size. (C) 2009 Elsevier B.V. All rights reserved.

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以青海省达日县高寒草甸原生高寒嵩草(Kobresia)草甸封育系统为对照,研究了土地退化对植被生产力的影响,检验了不同人工重建措施(两个人工种植处理:混播(HB)、翻耕单播(DBF)和1个退化草地封育自然恢复处理(NR)及1个退化草地自然状态(SDL))对植被生产力的相对影响程度。结果表明,原生植被封育处理(YF)地上总生物量为265.1g•m~(-2),混播(HB)和翻耕单播(DBF)处理中地上总生物量分别为原生植被封育处理的116%和68%。退化草地封育自然恢复处理(NR)和重度退化自然状态下地上总生物量分别为原生植被封育的76%和53%。YF处理根系生物量远大于其它处理。原生植被封育系统中植被地上部分碳储量为110.14g•m~(-2),地下根系(0~30cm)碳储量为2957g•m~(-2),植被总碳储量为3067.14g•m~(-2);重度退化草地系统中植被地上部分碳储量为57.07g•m~(-2),地下根系(0~30cm)碳储量为357g•m~(-2),植被总碳储量为414.07g•m~(-2)。由此可见,高寒草甸严重退化后,通过植物组织流失的碳达到2653.35g•m~(-2),即86.5%的碳损失;原生植被封育系统植被总氮储量为56.85g•m~(-2),而重度退化草地植被总氮储量为18.02g•m~(-2),高寒草甸严重退化使植物组织68.30%氮损失。与重度退化地相比,由于恢复重建措施增加了植物的生物量输入和群落组成,除翻耕单播处理外,其它恢复重建措施均能恢复系统植被的碳氮储量。这些恢复重建措施将会逐步改善土壤的物理和化学特性,最终使这些生态系统逐步由碳源向碳汇方向的转变成为可能。

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从二叶獐牙菜(Swertia bifolia Batal.)的全草中分离得到了7个化合物,5种口山酮和2种甾醇类化合物.它们的结构经光谱方法分别鉴定为1-羟基-3,5-二甲氧基口山酮(Ⅰ)、1-羟基-3,7,8-三甲氧基口山酮(Ⅱ)、1,8-二羟基-3,5-二甲氧基口山酮(Ⅲ)、1,8-二羟基-3,7-二甲氧基口山酮(Ⅳ)、1,7-二羟基-3,8-二甲氧基口山酮(Ⅴ)、β-谷甾醇(Ⅵ)、胡萝卜苷(Ⅶ).

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植物繁育系统是当今进化生物学研究中最为活跃的领域。繁育系统是指代表所有影响后代遗传组成的有性特征和总和,主要包括形态特征、花的开放式样,花各部分的寿命、传粉者种类和频率,自交亲和程度和交配系统,其中酱系统是核心,我们重点综述了植物有性繁育系统研究中1)传粉模式的多样性,2)从历史发生角度利用系统发育方法检验花性状的演化和繁育系统的生态转变过程;3)近交衰退对植物生殖史的影响及其机制和4)混和交配系统的时空动态,维持机理以及进化趋势的最新研究结果。总结了繁育系统在研究花适应性,物种形成机制和濒危植物保护生物学中的重要作用。最后对今后的繁育系统研究提出了两点建议:1)正确理解和使用适应概念,更多地利用人工控制实验来检验花的适应价值和2)将分子技术和生态学结合起来,开展群落水平和种以上水平的繁育系统研究,比较驱动与传粉多样性密切相关的花多样性基因和自花,异花传粉基因的进化与分化。确定繁育系统相互作用中的关键因子。

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珠毛蟹甲草 ( Parasenecio roborowskii)是菊科千里光族中款冬亚族蟹甲草属的一种植物 ,在藏药上全草入药 ,有治疗哮喘等疾病之功效。本文首次观察了珠毛蟹甲草的大小孢子发生、雌雄配子体的发育 ,旨在为开发与利用该种植物提供有性生殖过程方面的基础资料。

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南山种羊场的育种方案是根据育种目标的4个选择标准,加权综合而形成。计算出的选择指数为:净毛质量+21.08;毛束长度+0.58;平均纤维直径-4.23;育成羊体质量+1.47。估测该方案每世代遗传进展为1.6~2.1,选择指数标准差依MOET功率而定,与传统的育种改良方案(每世代遗传进展约为选择指数标准差)相比非常有益。

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A feeding trial A as conducted at the farm of Qinghai Academy of Animal and Veterinary Science, Xining, China during 1996 - 1997 with three dry yak cows (initial body weight 163 - 197 kg, age 5 - 6 years) by using 3 x 3 Latin Square Design to determine the effect of levels of feed intake on digestion, nitrogen balance and purine derivative excretion in urine of yak cows. The animals were fed oat hay (nitrogen 13.5 g/kg dry matter (DM), metabolisable energy 8.3 MJ/kg DM), i.e., 0.3, 0.6 and 0.9 of voluntary intake (VI). Each intake treatment lasted for 17 days and the samples (feeds, faeces and urine) were collected during last 7 days of each period. The results indicate that digestibility of dietary DM, OM, NDF and ash declined when intake levels increased from 0.3 to 0.9 VI [DM, from 66.1% to 59.1% (P < 0.05); OM, from 68.1% to 59.9% (P < 0.05); NDF, from 62.1% to 54.3% (P < 0.05); and ash, from 33.9% to 11.8% (P < 0.05)]. Around 0.10 g N/kg W-0.75 was deficient daily in yak cows at 0.3 VI, and positive N balances were observed at 0.6 and 0.9 VI. Intake levels significantly (P < 0.05) affected total PD excretion in yak urine. The proportion of allantoin increased (P < 0.05) and uric acid decreased (P < 0.05) as intake level of feed increased. (C) 2004 Elsevier B.V. All rights reserved.

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自从1986年G. Binnig 等发明原子力显微镜(AFM)以来,纳米科技研究得到了快速发展,纳米科技研究的最终目标是从纳米甚至分子与原子尺度上制造功能器件或系统,而实现此目标的手段之一是研制能够在纳米尺度上进行精确可控操作的装置、方法与技术。对此,学者们对基于 AFM 的纳米操作进行了大量研究。基于AFM-Tapping模式的纳米观测与操作具有成本低、易实现性等特点,因而近年来成为纳米技术研究的热点。但基于AFM探针的纳米观测和操作的基本理论仍然很不完善,许多情况下缺乏基于探针观测与操作的纳观作用力的合理解释与描述,因此限制了基于探针的纳米技术发展。为了解决这一问题,本论文在国家自然科学基金项目“基于机器人化的纳米操作方法研究(60575060)”的支持下,广泛收集和查阅国内外相关资料,重点开展了AFM-Tapping模式下探针动力学解释方法与建模研究,并进行了基于AFM-Tapping的纳米操作方法研究。主要研究工作如下: 1)针对探针动力学建模问题,开展了基于Hamilton原理和变分原理的有边界条件的探针一维悬臂梁建模方法研究。利用模态叠加法和模态函数正交性对探针各阶模态进行了解耦分析,得到了解耦的探针动力学方程。 2)开展了纳观尺度下探针-样品作用力研究。分析与阐述了毛细力、接触力和摩擦力等纳观尺度作用力;开展了基于Lennard-Jones势模型的不同形状探针与样品间的相互作用势描述方法研究;并根据势能-力之间的关系,研究了可描述半球形探针与样品间相互作用力的数学表达式。 3)开展了基于弹簧振子模型的纳观非线性力作用下探针振动问题分析研究。首次提出了基于探针弹性力与非线性纳观力平衡关系的探针振动状态区域划分方法。在探针振动能量平衡分析的基础上,研究了AFM-Tapping模式中的双稳态现象,进而得到了描述双稳态现象的解析表达式。最后采用Lyapunov指数分析的方法,证明了探针在非线性振动中确实存在着混沌现象。 4)研究了基于AFM-Tapping模式的纳米操作方法。通过研究探针振幅调节控制和预编程作业轨迹规划策略,提出了一种具有增强探针概念的纳米作业方法。该方法可以在参数设定和预编程条件下自动完成纳米尺度的平移和旋转操作,从而可以大大提高纳米操作的效率和精度。实验结果验证了该方法的有效性。本文的工作为纳米操作方法的研究提供了可以借鉴的理论与实验经验,有助于推动基于AFM的纳米操作与制造技术的发展。

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Anduo area is located in the Central Tibet, the middle segment of the Bangonghu-Nujiang suture. Anduo Block is the northern part of Lhasa terrane. The relationships among the different geological bodies were determined during the 1: 250000 regional geological surveying. Petrography, petrologic geochemistry, isotopic geochemistry and geochronology of igneous rocks from the suture and granitoids from Anduo Block were analyzed systematically as a whole for the first time. Then, their tectonic setting and history are discussed.Anduo ophiolitic melange consists of metamorphic peridotites, cumulates, plagiogranites, sheeted dykes swarm, pillow lava and radiolarian cherts. The concentration of Cr and Ni in the metamorphic peridotites is very high, with Mg# about 0.94 ~ 0.97, higher 87Sr/86Sr and Pb isotopic ratios, and lower 143Nd/i44Nd ratio. LREE is enriched relative to HREE and positive Eu anomaly is very clear. The REE distribution curve is U shape. Nb and Ta anomalies from cumulate gabbro and sheeted dyke swarm are not clear, while that are slightly negative from pillow lava. Plagiogranite belongs to strong calc-alkaline series with high Si, middle Al, low Fe, Mg and low K contents. Eu anomaly (~ 1.23) from plagiogranites is slightly positive. The character of all components of ophiolite is similar to that of the MORB, while to some extent the ophiolite was influenced by crustal material. Anduo ophiolite formed in a mature back-arc basin. Additionally, intermediate acidity volcanic rocks within Anduo phiolite melange are island arc calc-alkline rocks related to ocean subduction.The early-middle Jurassic plutonic rocks are tonalite, granodiorite bearing-phenocryst, magaporphyritic hornblende monzogranite, magaporphyritic monzogranite, monzogranite bearing-phenocryst and syenogranite in turn. They belong to calc-alkaline series which developed from middle K to high K series temporally. REE distribution curves of all plutonic rocks are similar and parallel to each other. SREE and negative Eu anomaly values decrease. In the multi-element spider diagram, the curves of different plutons are similar to each other, but troughs of Nb, Sr, P and Ti from young plutons become more evident. This suggests that thereare some closely petrogenetic affinities among plutonic rocks which make up amagma plutonism cycle of the early-middle Jurassic. Magma source is mainly crustal,but abundant mafic microgranular enclaves within granitoids indicate that crastalmagma should be mixed with mantle-derived magma and the mantle-derived magmadecreased subsequently. Tonalite has features of I-type granite, magaporphyriticmonzogranite is transition type, and monzogranite bearing-phenocryst is S-typegranite. The characteristic of granitoids from Anduo Block suggest that the formingtectonic setting is active continental margin.Reliable zircon U-Pb SHRIMP ages are obtained in the study area firstly. Plagiogranite from the Anduo ophiolite of the Bangonghu-Nujiang suture is 175.1 Ma, and granitoids from Anduo Block is 172.6-185.4 Ma. Additionally, plagioclase from the plagiogranite dates a 40Ar/39Ar age of 144 Ma, while biotite and hornblend from granitoids of Anduo Block give a 163-165 Ma.Similar cooling ages of plagiogranite from the Anduo ophiolitic melange and granitoids from Anduo Block and the spatial distribution of the ophiolitic rocks between Anduo, Naqu, and Shainzha area suggest that bilateral subduction of the Bangonghu-Nujiang oceanic basin took place in the early-middle Jurassic. During this subduction, Anduo ophiolitic rocks were related to north subduction of the Bangonghu-Nujiang oceanic basin and Anduo back-arc basin spreading, while granitoids from Anduo Block were related to south subduction.

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分散元素广泛应用于高新技术领域, 具有重要的经济价值, 但因其在地壳中的低含量和其本身地球化学性质的分散性而不易富集成矿, 但是富乐铅锌矿床中却有4 种分散元素Cd, Se, Ge, Ga 具有工业价值。该矿床位于我国重要的川滇黔多金属成矿带南东部,分散元素主要赋存在闪锌矿中, 平均w (B)ö10- 6分别为Cd 16 183, Se 163, Ge 135, Ga 86,其中w (Cd) 是迄今国内最高。闪锌矿分棕黑色、红棕色和黄棕色3 种颜色。Cd 在深色闪锌矿中而Ge 和Ga 在浅色闪锌矿中相对富集, Se 在不同颜色闪锌矿中含量几乎不变。Cd, Ge,Se 主要呈类质同象形式存在, Cd, Ge 占据Zn 的位置, 而Se 占据S 的位置。Ga 主要以显微吸附形式存在, 少量以类质同象形式存在。Zn 与Cd 负相关, 而与Ge 正相关, 与Se 不相关。分散元素地球化学特征指示矿床为沉积2改造成因。

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铜厂矿田是勉略阳“金三角”地区中重要的铜金多金属矿田。本文在深入研究铜厂矿田中铜厂地区断裂构造地球化学的基础上,认为构造地球化学异常集中区是进行铜金多金属矿预测的有利靶位,提出了新铜厂、黄泥梁、张家山、老铜厂等重点找矿靶区,其中部分靶区已证实。