936 resultados para 70-1


Relevância:

60.00% 60.00%

Publicador:

Resumo:

实验室条件下,利用根田鼠1~70日龄体重和体长数据,计算其肥满度指数,目的在于分析其生长发育的基本规律。结果表明,根田鼠1~70日龄肥满度存在性别差异且随日龄增加而增大;雌雄个体的发育不同步;常见曲线回归模型对根田鼠1~70日龄的肥满度不能准确拟合,根据其生长发育状况,将其划分为3个阶段(其中幼体和成体阶段各含2个阶段)。

Relevância:

60.00% 60.00%

Publicador:

Resumo:

利用Fenton反应产生的羟基自由基,采用比色法对大黄属药用植物:唐古特大黄、波叶大黄、穗序大黄不同部分提取液清除羟基自由基的活性进行了研究,结果表明:三种植物不同部分的提取液均有一定的清除羟基自由基的能力,清除能力因种、植株部分和提取方法的不同而异.三种植物中清除率最高的部分分别是:唐古特大黄根及根茎的水提液,为79.0%;波叶大黄叶片的乙醇提取液,为84.5%;穗序大黄叶片水提液和叶柄的乙醇提取液,分别为70.1%和70.7%.正品大黄植株地下部分清除率较非正品高,但地上部分清除率却低于非正品.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Based on the 16S mitochondrial partial gene sequences of 29 genera, containing 26 from Oedipodidae and one each from Tanaoceridae, Pyrgomorphidae and Tetrigidae (as outgroups), the homologus sequences were compared and phylogenetic analyses were performed. A phylogenetic tree was inferred by neighbor-joining (NJ). The results of sequences compared show that: (i) in a total of 574 bp of Oedipodidae, the number of substituted nucleotides was 265 bp and the average percentages of T, C, A and G were 38.3%, 11.4%, 31.8% and 18.5%, respectively, and the content of A+T (70.1%) was distinctly richer than that of C+G (29.9%); and (ii) the average nucleotide divergence of 16S rDNA sequences among genera of Oedipodidae were 9.0%, among families of Acridoidea were 17.0%, and between superfamilies (Tetrigoidea and Acridoidea) were 23.9%, respectively. The phylogenetic tree indicated: (i) the Oedipodidae was a monophyletic group, which suggested that the taxonomic status of this family was confirmed; (ii) the genus Heteropternis separated from the other Oedipodids first and had another unique sound-producing structure in morphology, which is the type-genus of subfamily Heteropterninae; and (iii) the relative intergeneric relationship within the same continent was closer than that of different continents, and between the Eurasian genera and the African genera, was closer than that between Eurasians and Americans.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Although studies show that grazing and browsing by herbivores have marked effects on host plants, the mechanisms remain unclear. The objective of this study is to determine the effects of sheep saliva on host plant growth. Sheep saliva was manually applied to clipped plants of two different life forms, a semi-shrub, Artemisia frigida Willd., and a herbaceous species, Leymus chinensis (Trin.) Tzevel. The results showed that sheep saliva significantly enhanced aboveground net primary productivity (ANPP) and the ratio of ANPP to belowground net primary productivity (BNPP) for both species. This indicated that sheep saliva promotes aboveground compensatory growth and allocation of photosynthate to aboveground for both plant species. Sheep saliva stimulated only tillering of L. chinensis. Regardless of saliva application, clipping significantly decreased BNPP and plant height, but significantly increased the number of branches or tillers for both plant species. The relative growth rates (RGRs) on both species were significantly greater after clipping with saliva compared with control and clipping without saliva treatments. In addition, RGR of the herbaceous species L. chinensis was faster than that of the semi-shrub A. frigida after application of saliva. (c) 2006 Elsevier Ltd. All rights reserved.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

随着经济建设的快速发展和电气化程度的不断提高,电机已被广泛应用于工业、农业、国防及人们日常生活的各个领域。从全球范围看,电机的用电量平均占世界用电总量的50%以上、占工业用电量的70%左右,然而在电机消耗的电能中有相当一部分被浪费掉了,其中电机带故障运行是造成电机运行效率偏低,能源浪费严重的主要原因之一。 电机在线监测及故障诊断系统对于减少由于电机故障引发的人员、财产的损失,减少由于故障引发的异常状态而导致的能源浪费有着重要的现实意义。在电机故障危害产生前发现故障并进行维护是电机故障诊断的核心思想,在保证电机故障诊断系统准确性的同时,系统的快速性与鲁棒性显得尤为重要。基于此,本论文从寻求系统的快速、稳定的性能入手,提出了基于符号时间序列分析的感应电机故障诊断框架,重点研究了计算代价小、噪声干扰不敏感的诊断方法,以期提高感应电机故障诊断系统的快速性与鲁棒性。论文的主要工作有: 1. 论文首先构建了一个基于符号时间序列分析的电机故障诊断框架,将电 机故障诊断分解为信号预处理、符号区间划分、符号统计分析三部分,有机地融合了统计分析、信号处理、信息论、模式识别等理论和方法,利用符号时间序列分析技术在强噪声中准确识别系统状态模式的良好性能,可以有效地解决电机故障诊断问题,并实现电机故障诊断量化分析,是对探索电机在线监测与诊断新方法的一次有益的尝试。 2.引入提升小波对信号进行前期处理,并针对常规提升小波固定预测滤波器的局限性,提出了基于梯度信息的自适应提升小波预测方法。该方法中预测滤波器并不是固定的,而是利用梯度的信息来确定预测算子。根据信号的陡峭程度选择预测算子可以更准确地预测信号,从而使原始信号中的平滑特征和陡峭特征可以在小波变换中完好地保留下来。仿真实验及实验室实验结果表明该方法可以有效地保留信号中蕴含的重要的特征信息,对于以提取、识别信号中特征信息为主的故障诊断技术来说具有非常重要的意义。 3.针对所采集现场信号的非均匀分布特点,论文提出了一种自适应符号化划分方法,既可以确保符号在数据密集区间和数据稀疏区间的合理分配,提高符号的利用率,又可以灵活地适应信号的特征,增强诊断系统对微弱故障信号的敏感度。故障诊断实验表明该方法简单有效,实现了故障初期的快速诊断,并且较平均区间划分方法有着更高的计算效率、更明显的诊断效果。 4.将相对熵的概念引入基于符号时间序列分析的电机故障诊断框架中,针对电机故障严重程度量化分析问题,提出了基于模糊相对熵及加权模糊相对熵的符号统计分析方法,并将该方法应用于感应电机的故障诊断与识别,建立了电机故障诊断模型。该方法可以更合理、充分地利用信息丰富的符号区间所蕴含的故障信息,实现了电机故障诊断与故障严重程度的识别。实验结果验证了该方法的合理性、有效性和可靠性。 5.将隐马尔可夫模型(HMM)引入到基于符号时间序列分析的电机故障诊断框架中,构造了基于HMM的电机故障诊断模型,并对HMM阶数选取问题给出了一个基于符号出现不确定信息熵的HMM阶数选取原则,使得模型在满足精度要求的同时,又尽可能地减少模型的计算代价,有效地提高了故障诊断的效率及可靠性。实验结果表明基于HMM的电机故障诊断方法有效地实现了电机转子断条故障、匝间短路故障的诊断与量化分析。

Relevância:

60.00% 60.00%

Publicador:

Resumo:

随着陆地战略资源日益短缺以及经济的全球化进展,海洋资源的开发利用已成为沿海各国的重要发展战略之一,也成为地球资源保护与开发的关注热点。 海洋资源开发和利用能力对于一个国家的科研、经济实力具有重大的影响及意义。由于海洋资源开发利用和地球环境监测的迫切需求,促进了水下机器人、水下潜器等无人水中移动载体技术的发展。能源供给技术是水中移动载体系统的关键技术,能源技术对海洋人工系统的生存、作业、自主能力提升具有重要意义。目前海洋移动人工系统主要依赖自携带能源形式,针对水中移动载体的能量自补给技术研究还处于探索阶段。 地球表面有70%的面积被海水所覆盖,海水中蕴藏巨大的波浪能。具有环保、再生特色的波浪能开发利用技术长期以来一直受到国内外科研人员的关注。随着海洋战略地位的提升,海洋自主人工系统已成为海洋科学技术的重点发展内容。利用波浪能为海洋人工移动载体进行能量补给,是对于海洋波浪能利用的一种新的方法和思路。这对于提高海洋人工系统的自主生存、续航能力,提高人类在海洋资源与环境的探测、开发利用等方面的技术能力无疑具有重大意义。因而研究面向海洋人工系统的波浪能利用机理和系统实现技术无疑具有广泛的应用前景。 本文针对海洋人工移动载体自主能量获取利用这一重大科学技术需求,依托中国科学院基地创新基金项目“基于惯性摆原理的无源系统研究”,探索基于惯性摆机理的移动载体波浪能自主获取的机理,研究相关设计理论和技术方法。 由于目前尚无基于惯性摆机理的海洋移动载体能量自补给技术的相关研究成果。因而本论文的研究主要从理论分析和实验方法两个方面开展。重点分析了惯性摆的外激励能量获取机理,基于惯性摆的波浪机械能获取理论的可行性;开展了惯性摆载体的水动力学建模,原理样机的仿真,频域下的能量建模和优化,非线性波浪条件模拟,惯性摆载体的能量获取结构优化等研究工作。主要研究工作如下: 1.针对基于惯性摆机理的移动载体随机波能获取研究方案,分析了相关单摆及惯性摆机械能量转换机理,采用动量及动量矩定理,构建了惯性摆载体的六自由度运动学和动力学方程。 2.进行了相关水动力系数获取方法研究,获得了水动力系数数学描述。同时,采用虚拟样机方法进行惯性摆载体能量获取的研究,证明了基于惯性摆的波能自主获取方法的可行性及有效性。 3.针对虚拟样机方法建模的复杂性及容易产生错误等问题,进行了基于BP神经网络方法的惯性摆能量吸收效率的建模研究。并研究了基于该模型的不同波向角及波浪频率、载体外形尺寸、质量等的虚拟样机的波浪能吸收效率问题,为载体机构的改进及设计提供了较好的理论模型和基础。 4.开展了频域下惯性摆能量吸收效率研究。研究了基于频域的单惯性摆载体的动力学建模方法以及载体结构优化方法,提出采用多种群遗传算法进行载体结构的优化设计方法。通过仿真实验证明了相关算法的有效性,为系统的优化设计研究提供了理论基础。 5.以能量吸收效率最大为目标,进行了多种惯性摆形式的能量获取最大化分析研究,提出了包括单摆在内的多种可行的形式,给出了对比研究结果,可根据不同的提取形式而确定采用的惯性摆的形式。 6.采用PM谱对非线性波浪进行了模拟,研究了单惯性摆结构在非线性波浪力下的能量获取情况,仿真结果表明,在非线性条件下获取的惯性摆能量要更多,而其他波向角、频率等优化条件均与线性条件下的研究结果相同。

Relevância:

60.00% 60.00%

Publicador:

Resumo:

通过对贵阳市红枫湖中溶解态锌、颗粒态锌及颗粒态锌中不同结合形态的研究,探讨了红枫湖生物地球化学过程中锌的主要赋存形态与季节性变化规律。结果发现,红枫湖总锌的质量浓度为0.72ug·L^-1~13.04ug·L^-1,污染较轻。红枫湖南湖总锌全年均高于北湖,主要是位于南部的羊昌河输入所致。红枫湖水体中锌的主要赋存形式是溶解态锌(占总锌的70%1;颗粒态中AEC(吸附态-可交换态-碳酸盐结合态)结合态锌是最主要的赋存形式(占颗粒态锌的72%)。溶解态锌含量夏季低而冬季高,主要是因为夏季生物吸收与吸附、以及冬季沉积物孔隙水向上覆水体的释放。颗粒物中有机结合态锌的变化主要受湖泊藻类繁殖的影响

Relevância:

60.00% 60.00%

Publicador:

Resumo:

瑶岗仙钨矿区地处南岭中段,位于加里东隆起带与印支-燕山凹陷带的交汇地带。为了更深入地研究瑶岗仙钨矿成矿流体的性质和演化,在前人工作的基础上,本文结合流体包裹体的岩相学特征及其产出的构造特征,对瑶岗仙钨矿流体包裹体进行了显微测温和激光拉曼探针分析,从而确定了瑶岗仙钨矿成矿流体的性质,并进一步探讨了其成矿物质来源及成矿机制。 对瑶岗仙石英脉型钨矿床的石英、萤石和矽卡岩型钨矿床中石榴子石流体包裹体的岩相学特征研究表明,与成矿有关的包裹体主要有三类:富液相、富气相和含子晶多相包裹体。脉型钨矿床中石英的包裹体均一温度范围 180℃~300℃,盐度为 0.88~6.45 wt% NaCl;矽卡岩钨矿床中石榴子石包裹体均一温度范围为 190~300 ℃,盐度为 0.1~8.95 wt% NaCl,成矿溶液的密度为 0.70~1.05 g/cm3,说明形成两种类型矿床的流体均属中温、低密度、低盐度流体;两类矿床形成的压力为 32~38 MPa,成矿深度为 1~2 km,因此该矿床是在浅成、低压条件下形成的。激光拉曼探针测试表明,石榴石包裹体的气相成分以 H2O 为主,石英中包裹体的气相成分及其相对含量为 H2O>CO2>CH4>N2>H2S。由此说明,从矽卡岩型白钨矿阶段到石英脉型黑钨矿阶段,成矿流体中不断有 CH4、CO2和H2O 等挥发份的加入,此时的流体是一种介于岩浆与热液之间的过渡性流体,具有上部偏液、下部偏浆的特点。 根据前人的研究结果以及矿脉中花岗岩角砾的发现,泥盆系、寒武系岩层在花岗岩浆侵入过程中发生了混合岩化,成为成矿物质来源的基础,而真正的成矿母岩应该是深部的花岗岩体,由此推测“赋矿花岗岩并非成矿源岩”,很可能来自深部母岩浆中熔离出的流体。而 CH4 等还原组分的含量增多,推测也有可能来自相对是还原环境的地幔过渡带或软流圈中。

Relevância:

60.00% 60.00%

Publicador:

Resumo:

基性岩类的(脱水)部分熔融实验是研究地球内部中酸性岩浆(熔体)形成的重要实验方法,自二十世纪70年代以来越来越受到地质学家的高度重视。华北北缘广泛分布的中生代埃达克质岩石的成因,十几年来引起国内外学者的激烈争论,至今仍没有定论。近年来的研究表明张家口地区同时出露的古老太古宙中基性下地壳岩石、中生代中酸性埃达克质岩浆岩以及汉诺坝基性麻粒岩包体等可能反映了源岩和熔融产物的综合信息,这为我们运用实验岩石学手段研究华北北缘埃达克质岩石成因提供了非常理想的条件。 本文在1.5-2.0GPa,800-1000℃条件下,对采自华北北缘的斜长角闪岩同时进行了块状与粉末状两种样品的部分熔融实验研究,利用电子探针对各实验产物进行了主量元素分析以及利用LA-ICP-MS对部分熔体进行了微量元素测试,进而比较了相同条件下块状和粉末状样品的熔融特征,并对比了实验获得的熔体与华北北缘中生代埃达克质岩石的地球化学特征,同时也将实验获得的残留体与汉诺坝基性麻粒岩包体进行了比较。获得以下主要认识: (1)相同的温度、压力和恒温时间条件下块状样品的熔融温度比粉末样品的更低。在1.5-2.0GPa,800℃时块状斜长角闪岩样品已经发生部分融融,而相同条件下粉末样品中没有观察到熔体,粉末样品的部分熔融发生在850℃左右。在850-1000℃温度范围内,相同条件下块状样品的熔体含量比粉末样品的熔体含量高出5-17vol.%,即相同条件下块状样品比粉末样品的熔融程度更高,说明块状样品更容易达到可以分凝形成岩浆的临界熔体分数(CMF),这可能暗示着自然界中的岩浆形成可能比以往通过粉末实验结果推测的更容易发生。此外,在较高的温度条件下(950-1000℃),块状样品与粉末样品的熔体在主量和微量元素上都具有大致相同的地球化学特征,可以认为二者在在岩石学应用上是等效的。 (2)1.5GPa下实验获得的熔体为花岗质-花岗闪长质熔体,850-1000℃熔体的主-微量元素的地球化学特征与华北北缘中生代埃达克质岩石的整体特征具有很好的相似性,并与实验原岩产地张家口地区的三个典型中酸性埃达克质岩体的地球化学特征类似。可以认为实验的斜长角闪岩在1.5GPa下部分熔融能够形成华北北缘中生代埃达克质岩石。2.0GPa下的实验熔体为花岗质-奥长花岗质成分,其主量和微量元素特征均与华北北缘埃达克质岩石存在较大的差别,说明该压力下不能够形成华北北缘埃达克质岩石。 (3)实验残留相主要组成为Hb+Cpx+Gt±Pl,相当于麻粒岩相或榴辉岩相的矿物组合。与汉诺坝基性麻粒岩包体的典型矿物组合Cpx+Opx+Pl存在较大差别,在化学成分上,残留相比麻粒岩包体也整体上富Fe、Al,而贫Mg、Ca。综合来看汉诺坝基性麻粒岩包体可能是多种源岩在相对低压的条件下经过多期部分熔融综合作用的结果,本次实验的原岩及条件难以完全解释其复杂的成因。 另外,针对实验熔体和华北北缘埃达克质岩石之间的一些差异,不排除可能同时存在其他与之类似的源岩,成分上具有相对富Mg、Ca而贫Fe、Al,以及不同程度的Th、U、Zr、Hf富集等特征,与斜长角闪岩一起部分熔融,共同形成中生代华北北缘的中酸性埃达克质岩石。

Relevância:

60.00% 60.00%

Publicador:

Resumo:

PURPOSE: The association of continuous infusion 5-fluorouracil, epirubicin (50 mg/m2 q 3 weeks) and a platinum compound (cisplatin or carboplatin) was found to be very active in patients with either locally advanced/inflammatory (LA/I) [1, 2] or large operable (LO) breast cancer (BC) [3]. The same rate of activity in terms of response rate (RR) and response duration was observed in LA/I BC patients when cisplatin was replaced by cyclophosphamide [4]. The dose of epirubicin was either 50 mg/m2 [ 1, 2, 3] or 60 mg/m2/cycle [4]. The main objective of this study was to determine the maximum tolerated dose (MTD) of epirubicin when given in combination with fixed doses of cyclophosphamide and infusional 5-fluorouracil (CEF-infu) as neoadjuvant therapy in patients with LO or LA/I BC for a maximum of 6 cycles. PATIENTS AND METHODS: Eligible patients had LO or LA/I BC, a performance status 0-1, adequate organ function and were <65 years old. Cyclophosphamide was administered at the dose of 400 mg/m2 day 1 and 8, q 4 weeks and infusional 5-fluorouracil 200 mg/m2/day was given day 1-28, q 4 weeks. Epirubicin was escalated from 30 to 45 and to 60 mg/m2 day 1 and 8; dose escalation was permitted if 0/3 or 1/6 patients experienced dose limiting toxicity (DLT) during the first 2 cycles of therapy. DLT for epirubicin was defined as febrile neutropenia, grade 4 neutropenia lasting for >7 days, grade 4 thrombocytopenia, or any non-haematological toxicity of CTC grade > or =3, excluding alopecia and plantar-palmar erythrodysesthesia (this toxicity was attributable to infusional 5-fluorouracil and was not considered a DLT of epirubicin). RESULTS: A total of 21 patients, median age 44 years (range 29-63) have been treated. 107 courses have been delivered, with a median number of 5 cycles per patient (range 4-6). DLTs on cycles I and 2 on level 1, 2, 3: grade 3 (G3) mucositis occurred in 1/10 patients treated at the third dose level. An interim analysis showed that G3 PPE occurred in 5/16 pts treated with the 28-day infusional 5-FU schedule at the 3 dose levels. The protocol was subsequently amended to limit the duration of infusional 5-fluorouracil infusion from 4 to 3 weeks. No G3 PPE was detected in 5 patients treated with this new schedule. CONCLUSIONS: This study establishes that epirubicin 60mg/m2 day 1 and 8, cyclophosphamide 400mg/m2 day 1 and 8 and infusional 5-fluorouracil 200 mg/m2/day day 1-21. q 4 weeks is the recommended dose level. Given the encouraging activity of this regimen (15/21 clinical responses) we have replaced infusional 5-fluorouracil by oral capecitabine in a recently activated study.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

ABSTRACT: At a large North Sea pockmark, with active methane seeps, surface sediments were found to have higher insoluble sulphide concentrations than sedlments from the surrounding area. The fauna of the pockmark was characterized by 2 species which have not pi-evlously been reported from the Fladen Ground in the northern North Sea. These species were a b~valve, Thyasira sarsi (which is known to contain endosymbiotic sulphur-oxidising bacteria) and a mouthless and gutless nematode, Astomonerna sp., which also contains endosymbiotic bacteria The nematode was the dominant meiofauna species in the pockmark sediments. Both macro-lnfauna and total nematodes were in low abundance in samples taken from the base of the pockmark. Sediment samples from the pockmark contained numerous otoliths, implying that substantial winnowing of the sediment had taken place. This was supported by studies on the sulphide concentrations in the sediment which showed multiple layering of the sediments on the sides of the pockmark, suggesting displacement. The carbon isotope compositions (6I3c) of the tissues of benthic animals from in and around the pockmark were generally in the range -16 to -2O%, indicating that little methane-derived carbon was contributing to their nutrition. T sarsi had the most 13c-depleted tissues, -31.4 to -35.1 L, confirming the nutritional dependence of this species on chemoautotrophic bacteria that utilize reduced sulphur.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

1. The energy contributions of aerobic metabolism, phosphoarginine, ATP and octopine in the adductor muscles of P. magellanicus were examined during swimming and recovery. 2. A linear relationship was observed between the size of the phosphoarginine pool and the number of valve snaps. A linear increase in arginine occurred during the same period. 3. 3. Octopine was formed during the first few hours of recovery, particularly in the phasic muscle. 4. The restoration of the phosphoarginine pool appeared to be by aerobic metabolism. 5. It is concluded that the role of octopine formation is to supply energy when the tissues are anoxic and to operate at such a rate as to maintain the basal rate of energy production.