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 ,f_(αα)=0.0623641 a. ,fαα=0 0623641a. 短句来源 EXCITATION FUNCTIONS FOR THE ~(55)Mn(α,n) ~(58m,g)Co, ~(55)Mn(α,2n) ~(57)Co AND ~(55)Mn(α, α'n) ~(54)Mn REACTIONS ~(55)Mn(α,n)~(58m,g)Co,~(55)Mn(α,2n)~(57)Co和~(55)Mn(α,α′n)~(54)Mn反应的激发函数 短句来源 The values of ααα C_(29) sterane's 20S/(20S+20R) and C_(29) sterane's αββ/(ααα+αββ),the diagnostic indexes for low-mature oil in this sag,are 0.31 and 0.29,respectively. 该凹陷低熟油判识指标αααC29甾烷20S/(20S+20R)和C29甾烷αββ/(ααα+αββ)值分别为0.31和0.29; 短句来源 Recurrence sequence {αi,j} with ααi-1,j-1+βαi-1,j=αi,j is studied. 研究了满足ααi-1,j-1+βαi-1,j=αi,j的序列{αi,j}. 短句来源 It is suggestedthat the 5α--C_(27) Sterane ββ/ (αα+ββ) and 5α-C_(29) Sterane 20S/ (20R+20S)are the main indices of crude oil maturity, while the relative abundance ofrearranged Sterane, 4-methylsterane and Tm/Ts are of secondary importance. 5 α-C_(27)甾烷的ββ/(αα+ββ)和5α-C_(29)甾烷的20S/(20R+20S)是反映原油成熟度的主要指标,重排甾烷相对丰度、4-甲基甾烷相对丰度和Tm/Ts是原油成熟度的辅助指标。 短句来源 更多
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 α . α。 短句来源 If R satisfies the condition <α>,R is commutative. <α>:For (?) <α>:(?) 短句来源

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 alpha alpha
 Type 2 are injected with the conditional probability $\alpha\alpha2$, where $0\leq\alpha2 = n\alpha\leq\alpha$ and n is the concentration of type 2. We prove that this estimator is asymptotically exact in the energy norm for regular solutions and $$O(h^{1+\alpha})\ (\alpha >amp;gt; 0)$$ meshes. We provide a computer program that calculates chargino and neutralino masses with complex parameters up to $\mathcal{O}(\alpha\alpha_{\text{S}})$. Analysis of the alpha-globin gene revealed -alpha3.7/alpha alpha genotype. We consider the relativistic α-stable process, a pure jump Markov process generated by $\mathcal{H}^{\alpha} = (-\Delta + m^{2/\alpha})^{\alpha /2}-m$. 更多
 The synthesis of dl-threo-3-chloro-3-phenyl-2-aminopropanol hydrochloride (Ⅳ),a usefulintermediate for the preparation of racemic chloramphenicol~[4] ,has been achieved by treating1-phenyl-2-amino-3-ethoxypropanol hydrochloride (Ⅴ),m.p.119-120°,with concentrated hydro-chloric acid in sealed tube; the ethoxy group being converted to hydroxyl,and the replacementof secondary hydroxyl by chlorine having also taken place.The compound V was in turnprepared by a 3-step synthesis starting with ethyl α-benzoyl-β-ethoxyacrylate... The synthesis of dl-threo-3-chloro-3-phenyl-2-aminopropanol hydrochloride (Ⅳ),a usefulintermediate for the preparation of racemic chloramphenicol~[4] ,has been achieved by treating1-phenyl-2-amino-3-ethoxypropanol hydrochloride (Ⅴ),m.p.119-120°,with concentrated hydro-chloric acid in sealed tube; the ethoxy group being converted to hydroxyl,and the replacementof secondary hydroxyl by chlorine having also taken place.The compound V was in turnprepared by a 3-step synthesis starting with ethyl α-benzoyl-β-ethoxyacrylate (Ⅵ).The latterwas subjected to catalytic hydrogenation in the presence of Raney nickel with simultaneousreduction of the double bond and the carbonyl group to form ethyl α-ethoxymethyl-β-hydroxy-β-phenylpropionate (Ⅶ),b.p.145-148°/2 mm.The second step was to convert the ester byusual way to its amide (Ⅷ),m.p.128. 5-129°,from which the compound (Ⅴ),(hydro-bromide:m.p.129°,picrate:m.p.163°) was obtained by Hofmann reaction.Ikuma~[3] found that either threo-or erythro-1-phenyl-2-amino-1,3-propanediol (Ⅲ)gavethe same dl-threo (Ⅳ) on treatment with thionyl chloride,so by analogy no conclusion could bedrawn as to the configuration of the compounds Ⅴ,Ⅶ and Ⅷ,although the dl-threo-Ⅳactually resulted.The preparation of a homolog of Ⅶ,methyl α-methoxymethyl-β-hydroxy-β-phenyl-propionate (Ⅹ),b.p.146-149°/1. 5-2 mm,was also attempted.The condensation of benzal-dehyde with α-bromo-β-methoxypropionate (Ⅸ) by Reformatsky reaction led to the desired pro-duct but with extremely poor yield.The experiment,however,showed that the Reformatskyreaction is possible to take place with a compound such as Ⅸ containing a methoxy groupin the β-position of the α-bromoester.The present work also dealt with the condensation of a β-ketoamide with formaldehyde.Our experiments indicated that the reaction of benzoylacetamide or p-nitrobenzoylacetamidewith this reagent in the presence of potassium or sodium acetate led to the formation of aproduct involving the condensation of two molecules of the corresponding amide with onemolecule of formaldehyde to form αα′-dibenzoylglutaramide (ⅩⅤ),m.p.197-198°(dec.),orαα′-di-p-nitrobenzoylglutaramide (ⅩⅥ),m.p.193-194°(dec.).The structure of ⅩⅤ was con-firmed by hydrolysis to 1,3-dibenzoylpropane (ⅩⅦ),which gave no melting point depressionwith authentic sample.The condensation of ethyl p-nitrobenzoylacetate with an excess of formaldehyde gave rise toethyl αα′-dihydroxymethyl-p-nitrobenzoylacetate (ⅩⅧ),m.p.125-126°. 1. 本文叙述了从α-苯甲醯-β-乙氧基丙烯酸乙酯开始经过四个步骤合成了制备氯霉素的有用中间体--dl-threo-3-氯代-3-苯基-2-氨基丙醇盐酸盐(Ⅳ)。2. 用 Reformatsky 反应合成了α-甲氧甲基-β-羟基-β-苯基丙酸甲酯(Ⅹ),虽然产量甚小,但说明了β位置含有甲氧基的α溴酯化合物可以应用于 Reformatsky 反应,而所得的产物为相应的β羟基酸酯而非不饱和酸酯。3. 进行了β羰基醯胺与甲醛的缩合,结果所得者为二分子β羰基醯胺与一分子甲醛缩合成戊二酸醯胺衍生物,而未取得羟甲基化合物。 4. 对硝基苯甲醯乙酸乙酯与过量的甲醛进行缩合,结果获得双羟甲基化合物,αα′-双-羟甲基-对硝基苯甲醯乙酸乙酯(ⅩⅧ)。 The decreases in lattice strain △a/a in cold-drawn steel wires after annealing between 150℃ and 450℃ have been determined by measuring the broadening of DebyeScherrer lines.The decrease in △a/a is accompanied by an increase in the fatigue strength of smallwire ropes with little effect on their tensile properties.The distribution of △a/a in thewires was also examined. 将铅浴处理后经过冷拔的硬钢缓进行低温退火,退火采用普通及导电两种加热方法;从测量钢线的X射线衍射谱线宽度求出退火温度增高时二类畸变△α/α的下降数值,同时,测定了部分试样的力学性能,以资比较.从试验结果中选择了一定的温度进行了小钢绳的疲劳试验,初步试验结果:低温退火对于提高钢线的耐疲劳性能有明显效果.在文中并讨论了钢线中△α/α的不均匀分布情况。 The sound velocity in a fibre shows a pronounced anisotropy, that is, the sound velocity along the axis of an oriented fibre is much greater than that perpendicular to it, and therefore it may be used as a measure of the molecular orientation α in the fibre,α= 1 - Cα2/C2where C and Cu are velocities of sound along an oriented fibre and a completely un-oriented fibre respectively.The apparatus used consisted of a pulse generator which sends a pulse of 70 μsec duration with a repetition frequency of 100 times... The sound velocity in a fibre shows a pronounced anisotropy, that is, the sound velocity along the axis of an oriented fibre is much greater than that perpendicular to it, and therefore it may be used as a measure of the molecular orientation α in the fibre,α= 1 - Cα2/C2where C and Cu are velocities of sound along an oriented fibre and a completely un-oriented fibre respectively.The apparatus used consisted of a pulse generator which sends a pulse of 70 μsec duration with a repetition frequency of 100 times per second to the moving coil of a loud speaker. The fibre was coupled to the vibrating membrane through a spring clamp. When exited by the pulse, the system underwent damped oscillation with a natural frequency of about 4000 Hz. At the other end of the fibre, about 200 cm from the clamp, a crystal pick-up was located, the output of which was sent to an oscilloscope with the sweep circuit triggered by the pulse voltage. The time of propagation of the longitudinal vibration along the fibre from the clamp to the pick-up was observed from the oscilloscope record, and the sound velocity in the fibre calculated.Since the mechanical properties of fibre depend considerably on the moisture regain and tension, the effect of relative humidity and tension in the fibre on the sound velocity were studied.The best choice of the experimental conditions for the determination of molecular orientation by the sound velocity method appears to be the following: room temperature, 28 - 30℃; relative humidity, 60%; and under a tension somewhat below the critical Young's modulus of the fibre.The sound velocities in the fibres of different draw ratios (r) were determined and extrapolated to r = 1 to give the value for Cu. Experimental results indicate that the degree of molecular orientation of monofils of Nylon 6 increases to approximately 80% after drawing and after-treatment.The degree of orientation for several products of Nylon 6 fibre such as yarns, monofils, and cords was determined. Fibres that possess greater breaking length show higher degree of orientation. 纤维具有声学的各向异性,声波通过纤维的速度与纤维中高分子链的取向程度有关。测定声波沿纤维轴方向的传播速度可以计算纤维的取向度α: α=1-C~2_u/C~2其中C及C_u分别为声波通过取向及无规取向纤维的速度。 实验仪器采用每秒100次的脉冲电流输至高音喇叭的音圈,纤维通过弹簧夹子与喇叭振膜的中心相耦合。脉冲电流激发喇叭振膜振动系统,使产生逐渐衰减的固有频率振动(约4000赫)。离振源200厘米处的纤维另一端有拾音器,其输出讯号接至由脉冲电压触发扫描的脉冲示波器,从示波器可以观察到从振源到拾音器的距离间声波在纤维中的传播时间,由此计算出声波通过纤维的速度。 纤维的吸湿性与所受张力不同对其力学性貭均有影响,因此研究了相对湿度与张力对纤维中声速的影响,并选择了在室温(约30℃),相对湿度为60％和在小于纤维的临界杨氏模量的作用张力下进行声速法测定纤维的取向度。 研究了不同拉伸程度单纤维样品的声波传播速度,并外推到长度拉伸比为1时作为声波通过无规取向纤维的速度。实验结果表明,尼龙6纤维的取向度经拉伸与后处理逐渐增大至80％左右。 测定了不同品种的尼龙6纤维的取向度,具有较大强度的纤维其取向度较大。 << 更多相关文摘
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