955 resultados para Anos 50 e 60


Relevância:

80.00% 80.00%

Publicador:

Resumo:

Four 1-week trials were conducted to determine the effects of feeding rates on growth performance and body proximate composition of white sturgeon larvae during each of the first 4 weeks after initiation of feeding. Feeding rates (% body weight day(-1)) were 10, 20, 30, 40, 50, and 60 for trial I; 5, 10, 15, 20, 25, and 30 for trial II; and 2.5, 5.0, 7.5, 10.5, 12.5, and 15.0 for trials III and TV Four tanks with 200 larvae each were randomly assigned to each of the six feeding rates. Average initial body weights of the larvae were 49, 94, 180, and 366 mg, respectively, for trials I-IV. The larvae were kept at 19-20 degreesC in circular tanks and fed continuously one of two commercial salmonid soft-moist feeds using automatic feeders. Proximate composition (%) of the feeds for trials I-III and IV were 13.9 and 14.9 moisture, 52.5 and 50.0 crude protein, 10.3 and 12.9 crude fat, and 8.1 and 8.7 ash, respectively. Except mortality in trial I, gain per food fed in trial III, and body ash in all trials, growth performance and body composition were significantly (P<0.05) affected by all feeding rates. Broken line analysis on specific growth rates indicated the optimum feeding rates of white sturgeon larvae to be 26%, 13%, 11%, and 6% body weight day-respectively, for weeks 1, 2, 3, and 4 after initiation of feeding. (C) 2003 Elsevier Science B.V. All rights reserved.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

A rhabdovirus was found to be associated with a lethal hemorrhagic disease in the cultured Chinese sucker Myxocyprinus asiaticus Bleeker. The rhabdovirus was amplified and isolated from the infected GCO, (grass carp ovary) cells. In ultrathin sections of liver cells from the diseased fish, the virus particles exhibited the characteristic bacilliform morphology, and budded through vesicle membranes of the infected cells. The isolated rhabdovirus particles were found to have a bacilliform morphology with 2 rounded ends rather than a typical flat base. The virus particles were measured and ranged in size from 150 to 200 nm in length and 50 to 60 nm in diameter. Most other characteristics, including their size, extensive virus infectivity to fish cell Lines, strong cytopathogenic effects, stability at high temperatures, vesicle formation in infected cells, structure protein electrophoretic patterns and the presence of an RNA genome, very closely resembled those of other fish rhabdoviruses. At present it is not known if this is a novel virus species or if it is an isolate of a known fish rhabdovirus. Until a confirmed identification can be made, we will temporarily refer to this virus as Chinese sucker rhabdovirus (CSRV).

Relevância:

80.00% 80.00%

Publicador:

Resumo:

为确定保水剂的合理用量,于2008年5月在陕西米脂县进行保水剂不同用量玉米盆栽试验研究。盆栽试验设置了保水剂不同用量(0、30、40、5060 g)五个处理及保水剂与风干黄绵土配比用量(0、0.05%、0.10%、0.15%、0.20%、0.30%)6个处理,分别研究了保水剂不同用量与土壤水势、土壤含水量的关系及对土壤持水时间的影响。试验结果表明,土壤含水量高(>18%)时各处理土壤水吸力十分接近,在土壤吸水力相同时,随着保水剂用量的提高其土壤含水量也随着提高;保水剂用量越大的处理玉米存活的时间也越长,0.20%和0.30%处理玉米存活时间较对照长3 d;综合分析表明本试验中保水剂与黄绵土配比0.20%和0.3%应用效果较好。

Relevância:

80.00% 80.00%

Publicador:

Resumo:

根据番茄的生长发育特点,分别以50%、60%、75%田间持水量作为苗期、花期、结果期的土壤水分下限,按照不同的土壤水分上限设置不同的灌水量处理。对番茄不同生育期的灌水量、耗水量、产量、水分利用效率及其关系进行了研究。结果表明,灌水控制上限和下限之间存在交互效应,番茄灌水量、耗水量与其具有显著的正相关性;当灌水控制下限一定时,耗水强度和耗水模数随灌水控制上限的减小呈降低趋势;番茄苗期、花期和结果期的灌水控制上、下限(占田持)分别控制在50%~65%、60%~75%和75%~85%为宜。

Relevância:

80.00% 80.00%

Publicador:

Resumo:

采用分子束外延(MBE)技术,在GaSb(100)衬底上外延生长晶体结构完整和表面平整的Ⅱ型超晶格InAs(1.2 am)/GaSb(2.4 am).拉曼光谱表明:随着温度从70 K升高至室温,由于热膨胀作用和光声子散射过程中的衰减,超晶格纵光学声子拉曼频移向低波数方向移动5 cm~(-1),频移温度系数约为0.023 cm~(-1)/K.光致发光(PL)峰在2.4~2.8 μm,由带间辐射复合和束缚激子复合构成,2.55 μm PL峰随温度变化(15~150 K)发生微小红移,超晶格中InAs电子带与GaSb空穴带带间距随温度变化比体材料的禁带宽度小.PL发光强度在15~50 K随温度升高而升高,在60~150 K则相反,并在不同温度段表现出不同的温度依赖关系.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Blends of poly(ether-sulfone) (PES) and poly(phenylene sulfide) (PPS) with various compositions were prepared using an internal mixer at 290degreesC and 50 rpm for 10 min. The thermal and dynamic mechanical properties of PES/PPS blends have been investigated by means of DSC and DMA. The blends showed two glass transition temperatures corresponding to PPS-rich and PES-rich phases. Both of them decreased obviously for the blends with PES matrix. On the other hand, T-g of PPS and PES phase decreased a little when PPS is the continuous phase. In the blends quenched from molten state the cold crystallization temperature of PPS was detected in the blends of PES/PPS with mass ratio 50/50 and 60/40. The melting point, crystallization temperature and the crystallinity of blended PPS were nearly unaffected when the mass ratio of PES was less than 60%, however, when the amount of PES is over 60% in the blends, the crystallization of PPS chains was hindered. The thermal and the dynamic mechanical properties of the PPS/PES blends were mainly controlled by the continued phase.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Flexural fatigue tests were performed on an injection-moulded glass-fiber reinforced blend of polyphenylene ether ketone and polyphenylene sulfide composite using four-point bending at a series of fixed mean stress levels with varying stress amplitude. Attention was given to identifying the effects of mean stress and stress amplitude on the fatigue life and failure mechanisms. It was found that the fatigue life of the studied material decreased sharply with increasing stress amplitude at a constant mean stress level and also decreased at a fixed stress amplitude with increasing mean stress. However, analyses of the fatigue data and failure behaviour reveal that, for the studied material, fatigue failure mechanisms depend on the relative importance of mean stress and stress amplitude. At a mean stress level of 80% ultimate flexural strength, the failure results from accumulation of creep strain, while at mean stress levels of 40%, 50% and 60% ultimate flexural strength, the magnitude of stress amplitude influences the type of failure mechanism. As stress amplitude is reduced, the fatigue failure mechanism changes from matrix yielding dominated to crack growth dominated fracture.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

气候变化和异常是当今地球科学研究的重大课题之一,与人类的生存、发展密切相关。南海作为我国最大的边缘海, 位于夏季风气流上游, 同时,作为热带太平洋的边缘海,具有显著的年际变异特征。近年来,随着卫星资料的积累和产品化使得我们有机会对南海的上层海洋要素进行全面的直接的观察,并进行南海气候异常变异及其可预报性的研究。 本文的研究内容就是利用近年来卫星资料产品,对南海主要海面要素,包括海面风场(SW)、表层温度场(SST)、海面高度场(SSH)的气候变化趋势以及南海表层温度变异的可预测性进行细致的探讨,并且利用较新的分析方法对南海上层海洋要素在近年来的非线性变异特点进行了分析。主要工作包括: 1. 采用南海卫星高度计及具有高精度模式输出结果通过联合经验正交函数分解(EOF)得到空间分辨率为1/3°×1/3°的南海绝对动力地形及地转流的季节变化(1-12个月)。从地转流场可以看到南海内部的表层流场主要有3种流系:西边界流、离岸流及南海多涡涡旋结构。 2. 通过南海海表大气和海洋要素(SW、风应力、SST、SSH)的气候变化趋势分析计算得到南海SST平均增暖0.5K/decade,海面高度升高6.7cm/decade,表层风场东分量和北分量的变化趋势分别为0.5m/s/decade、-0.04m/s/decade。其中南海SST增暖趋势和海面抬升速率远大于全球增暖和海面抬升速率。 3. 对南海SW、SSH和SST的异常场的EOF分析揭示南海SW、SSH及SST的年际尺度变化均表现出与ENSO变异现象一定的相关性:其中南海SW的第一模态特征表现为海盆尺度的反气旋,是西太平洋反气旋的最西南的一部分。对应的时间系数函数(TCF)滞后Nino3.4指数3个月,相关系数较高为0.90。南海SW的第二模态特征表现为均一化的西南风,TCF与印度洋偶极子(IOD)指数有一定相关性:TCF超前IOD指数4个月,相关系数达到0.58,表明南海SW第二模态似乎可以用来作印度洋偶极子现象的一个前兆。南海SSH的EOF第一模态特征为沿着南海东边界低水位,对应的TCF滞后Nino3.4指数2个月时间,二者相关系数为0.94;南海SST的EOF第一模态特征表现为整个海盆的增暖,对应的TCF与滞后Nino3.4指数8个月,相关系数等于0.62。 4. 基于典型相关分析(CCA),利用南海SSTA滞后热带太平洋Nino指数及印度洋IOD指数的关系建立南海SSTA的统计预报模式。通过对南海SSTA后报试验(1993/1994-2004年10月)与持续性预报值的预报效果进行比较分析,表明基于CCA统计方法对南海SSTA后期预报在预报时效超过3个月以上时具有更好的稳定性,提前1~12个月的后期预报水平平均值为0.60左右,误差均方根大约0.2个标准差。综合热带太平洋Nino指数为预报因子作南海SSTA统计预报的平均水平为0.55左右,亦具有较好的稳定性。 5. 基于前馈型神经网络,对南海近年的表层要素场(SW、SSH、SST)作非线性EOF分析。其中非线性EOF第一模态方差贡献与线性EOF相比均相应提高:海面风场、海面高度场的非线性作用较强,非线性EOF第一模态对变量场的方差贡献与线性EOF方法相比分别从54.75%提高到67.26%和50.43%提高至60.24%,非线性曲率强的空间范围占据绝大部分南海海域;相比较而言,南海SSTA场的非线性EOF第一模态的方差贡献提高不明显,非线性特征明显的区域仅在南海北部和南部靠近大陆的海区。对南海SSTA场1982-2003年时间长度的数据进行非线性与线性EOF分析比较,发现南海SSTA在近20年的非线性EOF分析中得到的非线性特征更不明显,表明与前10年相比,南海近10年的南海SSTA场的非线性成分有所增强。

Relevância:

80.00% 80.00%

Publicador:

Resumo:

为了研究亲子分开后雄性柴达木根田鼠(Microtus limnophylus)对亲本尿气味的记忆持续时间,分别在未分开(20日龄),以及分开10d(30日龄)、20d(40日龄)、30d(50日龄)、40d(60日龄)时,以新鲜尿作为气味源,在行为观察箱中记录雄性柴达木根田鼠对不同气味源的行为响应模式。结果表明:(1)未分开时,雄鼠对父本气味的接近频次显著高于陌生雄鼠气味;分开10d时,雄鼠对父本气味的访问时间显著多于对陌生雄鼠气味的访问时间;分开20d时,雄鼠对陌生雄鼠气味的接近潜伏期极显著短于父本,对陌生雄鼠气味的访问时间极显著长于父本,其遭遇父鼠气味时的自我修饰频次显著少于陌生雄鼠气味。(2)分开30d后,雄鼠对父本和陌生雄鼠气味的行为响应没有明显差异。以上结果表明,在亲子分开20d时,雄鼠仍能识别父本与陌生雄鼠的气味;在分开30d后,雄鼠不再能够识别父本与陌生雄鼠的气味。(3)在未分窝时,雄性柴达木根田鼠幼仔对母本和陌生雌鼠气味的行为响应没有任何差异。(4)在分开10d时,雄性柴达木根田鼠对母本和陌生雌鼠气味表现出不同的行为响应模式;分开20~40d时,雄鼠对母本与陌生雌鼠气味的行为响应没有任何差异。以上结果表明,在亲子分开10d时,雄鼠仍能识别母本与陌生雌鼠的气味;在分开20d后,雄鼠不再能够识别母本与陌生雌鼠的气味。因此,雄鼠对父本气味的嗅觉记忆时间可以持续到亲子分开20~30d之间;其对母本气味的嗅觉记忆时间可以持续到亲子分开10d时。

Relevância:

80.00% 80.00%

Publicador:

Resumo:

2007年10~11月,应用蠕虫学完全剖解法对13只柯氏鼠兔进行了寄生虫检查。结果显示,柯氏鼠兔感染的线虫有四川曲殖线虫、Ohbayashinema erbaevae和Eugenurissp.,其感染率分别为46.14%、38.50%和7.60%;平均感染强度为33.33、5.80和1.00。柯氏鼠兔是这些线虫的新宿主,而Ohbayashine—maerbaevae线虫为中国新记录。四川曲殖线虫是Graphidiella olsoni线虫的同种异名。

Relevância:

80.00% 80.00%

Publicador:

Resumo:

目的:建立藏药二十五味鬼臼丸的定性定量方法。方法:采用TLC法对二十五味鬼臼丸中的沉香、诃子进行鉴别;采用RP—HPLC法,Symmetry C_(18)色谱柱(150mm×4.6mm,50μm),以甲醇-水(60:40)为流动相,流速1.0mL•min~(-1),检测波长为343nm,柱温30℃,进样量10μL,对二十五味鬼臼丸中的胡椒碱进行含量测定。结果:薄层斑点清晰,专属性强;胡椒碱浓度在2.24—11.20μg•mL~(-1)范围内线性关系良好(r=0.9991),平均回收率(n=6)为97.4%(RSD为1.7%)。结论:该方法快速、简单、准确,重复性好,可有效控制二十五味鬼臼丸的质量。

Relevância:

80.00% 80.00%

Publicador:

Resumo:

为研究亲子分开后雌性根田鼠对亲本气味的记忆持续时间,分别在未分开(20日龄)、分开10d(30日龄)、20d(40日龄)、30d(50日龄)、40d(60日龄)时,以新鲜尿作气味源,在行为观察箱中记录雌性根田鼠对不同气味源的行为响应模式,结果表明:(1)未分开时,雌鼠遭遇父本气味时自我修饰的频次极显著高于陌生雄鼠气味,在分开10d时,雌鼠接近父本气味的频次显著多于接近陌生雄鼠气味的频次,其对前者反标记显著少于后者;(2)分开20d后,雌鼠对父本和陌生雄鼠气味的行为响应无明显差异;(3)未分窝时,雌性根田鼠幼仔对母本和陌生雌鼠气味的行为响应无差异;(4)分开10-40d时,雌性根田鼠对母本和陌生雌鼠气味表现出不同的行为响应模式。以上结果表明,在亲子分开10d时,雌鼠仍能识别父本和陌生雄鼠的气味;分开20d后,雌鼠不再能够识别父本和陌生雄鼠的气味;在亲子分开40d时,雌鼠仍能识别母本和陌生雌鼠的气味。因此,雌鼠对父本气味的嗅觉记忆时间可以持续到亲子分开10-20d之间;而对母本气味的嗅觉记忆时间则可以持续到亲子分开40d以上。

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Pint?r, B.; Thom, S. D.; Balthazor, R.; Vo, H.; Bailey, G. J., Modeling subauroral polarization streams equatorward of the plasmapause footprints, Journal of Geophysical Research, Volume 111, Issue A10, CiteID A10306 RAE2008

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Głównym celem dysertacji jest interpretacja twórczości Bulanda al-Ḥaydarīego (iracki poeta kurdyjskiego pochodzenia (1926-1996)). Utwory Al-Ḥaydarīego zawierają w sobie charakterystyczne cechy współczesnego wiersza arabskiego. Opisują ponadto najważniejsze historyczne, społeczne i osobiste doświadczenia literackiego pokolenia tego poety, jak również innych członków społeczności arabskiej w okresie po II wojnie światowej. Praca doktorska składa się z dwóch części. Pierwszą część poprzedza krótki opis stanu badań nad liryką Al-Ḥaydarīego. W pierwszym jej rozdziale przedstawiono życiorys i biografię literacką poety oraz wyjaśniono pojęcia takie jak: ‘współczesna poezja arabska’, ‘wolna poezja’, ‘poemat prozą’ czy ‘ruch wolnej poezji’. Wspomniano również o głównych nurtach w poezji arabskiej w latach 50. i 60. XX w., jak również ukazano sposób, w jaki modernistyczni poeci postrzegali poezję. Natomiast w drugim rozdziale przedstawiono pokrótce charakterystyczne cechy (stylistyczne, składniowe i melodyczne) współczesnego wiersza arabskiego i zilustrowano je fragmentami utworów Al-Ḥaydarīego. Druga część dysertacji składa się z pięciu rozdziałów. W każdym z nich przedstawiono jeden lub kilka głównych motywów oraz ich różne warianty: w pierwszym rozdziale – motyw miłość, w drugim – motyw istnienia (życie i śmierć), w trzecim – motywy ojczyzny, obczyzny, zaangażowania społecznego twórcy i jego wyobcowania, w czwartym – motyw przestrzeni (np. dom, droga, raj, piekło) oraz w piątym – motyw czasu (przeszłość, teraźniejszość, przyszłość).

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências Farmacêuticas