历史查询   



 为了更好的帮助您理解掌握查询词或其译词在地道英语中的实际用法，我们为您准备了出自英文原文的大量英语例句，供您参考。 
Commonly used techniques such as circular convolution and symmetric extension can produce undesirable edge effects which propagate into the interior of the transformed data as the number of DWT iterations increases.


there exists a C∞ rank1 map f: I2→R1 such that f(A) has nonempty interior for some subset A ?I2 of critical points with finite Hausdorff dimension.


Interior point projected reduced Hessian method with trust region strategy for nonlinear constrained optimization


A interior point scaling projected reduced Hessian method with combination of nonmonotonic backtracking technique and trust region strategy for nonlinear equality constrained optimization with nonegative constraint on variables is proposed.


The new method is a combination of pivot method and interiorpoint method.

 更多 


 Creep under very small torsional stress has been investigated for 99.95% polycrystalline iron in the temperature range of 350°525℃. The general features of the creep curves obtained are essentially the same as those previously reported for 99.991% aluminum. The creep is shown to be consisted of two parts, one occurring at lower temperatures or shorter times and the other at higher temperatures or longer times. The first part of the creep is limited in extent and is associated with the viscous behavior of grain... Creep under very small torsional stress has been investigated for 99.95% polycrystalline iron in the temperature range of 350°525℃. The general features of the creep curves obtained are essentially the same as those previously reported for 99.991% aluminum. The creep is shown to be consisted of two parts, one occurring at lower temperatures or shorter times and the other at higher temperatures or longer times. The first part of the creep is limited in extent and is associated with the viscous behavior of grain boundaries. The activation energy for this grainboundary creep is 78,000 ± 4,000 calories per mole according to the present creep and stress relaxation measurements. This value is close to the activation energy for selfdiffusion of iron, a correlation which indicates that, in so far as to the mechanism of atomic migration is concerned, grain boundaries may not be very different from the interior of the grains.  用99.95％的多晶纯铁作了从350°525℃的扭转微蠕变及应力弛豫试验,所得结果的概貌与以前用多晶纯铝所得的基本上相同。从蠕变曲线上可以看出这蠕变是由两部分组成的:第一部分是在较低温度或较短时间内发生的,第二部分是在较高温度或较长时间内发生的。第一部分的蠕变是有限的,是由于晶粒间界的粘滞性滑移所引起。根据微蠕变及应力弛豫测量的结果,这一部分蠕变所包含的激活能是78,000±4,000卡/克分子。这个激活能(晶粒间界滑移激活能)的数值与纯铁自扩散的激活能很相近,表示晶粒间界与晶粒内部对于原子迁移的基本过程而言并没有显著的差异。 加碳于纯铁中对于这两部分的蠕变都有显著的影响。最值得注意的结果是含碳量少到0.0004％时已经使晶粒间界的粘滞性滑移受到显著的阻碍。这些发现在控制金属高温蠕变的问题上指出一个一般性的原则,对于以前所提出来的晶粒间界空穴模型也提供了一些新的实验证据。 根据加碳的实验结果,对于第二部分高温蠕变的机构也提出了一个初步的看法,这蠕变所包括的基本过程可能是晶粒内部的空穴中的原子重新排列。  A new approximation method is proposed in this article for the discussion of molecular structures,and this new method includes the two wellknown theories,molecular orbital theory and electronpair bond theory as two special cases.Let a molecule have n bonds and let the ith bond be described by the antisymmetrical twoelectron bond function ψ_i(v_(2i1),v_(2i)).(If there exist one electron,threeelectron or manyelectron bonds,they can be similarly described by the corresponding oneelectron,threeelectron... A new approximation method is proposed in this article for the discussion of molecular structures,and this new method includes the two wellknown theories,molecular orbital theory and electronpair bond theory as two special cases.Let a molecule have n bonds and let the ith bond be described by the antisymmetrical twoelectron bond function ψ_i(v_(2i1),v_(2i)).(If there exist one electron,threeelectron or manyelectron bonds,they can be similarly described by the corresponding oneelectron,threeelectron or manyelectron bond func tions.) Then the stationary state of the molecule is represented by the follow ing wave function Ψ, where the summation is over all permutations of 1,2,……,2n except those within the interior of the functions,since each ψ_i is already antisymmetrical.Obviously (2~n/((2n)/!))~(1/2) is the normalization factor. By quantum mechanics the energy of the molecule equals (1) here H_i,T_(ij) and S_(11)' are respectively the following three kinds of operators, (2) (3) (4) The third term of equation (1) is the exchange integral of electrons 1 and 1', while (1,2') is that of electrons 1 and 2'.According to the definition of bond functions,ψ_i may be written as (5) Substituting equation (5) into equation (1) and carrying out the integration over spin coordinates,we obtain (6) It can be easily seen from equation (6) that the combining energy of a mole cule consists of two parts,one being the binding energy of the bonds represent ed by the first term of equation (6),and the other being the interaction energy of the bonds denoted by the second term of that equation. If we choose certain functions φ_i~('s) involving several parameters and substi tute them into equation (6),we may determine the values of those parameters by means of the variation principle. For the discussion of bond interaction energies,we develop a new method for the evaluation of certain types of threecenter and fourcenter integrals.The interaction energy of a unit positive charge and an electron cloud of cylindrical symmetry distribution may be written as (7) where (8) and R_0~2=a~2+b~2+c~2 The interaction energy of two electron clouds both of cylindricalsymmetry distributions with respect to their own respective axes is evaluated to be (9) (10) where is to sum over j from zero to the lesser value of n2i and m, is to sum over i from zero to the integral one of n/2 and (n1)/2,and is to sum over all cases satisfying the relation =mj,while b_(n,n2i) represents the coefficient of x~(n2i) in the n th Legendre polynomial.  本文在分子结构理论方面,作了下列两点贡献:首先建议了用双电子或多电子键函数作为近似基础,来计算分子的近似能量和近似电子云分布。这样计算得来的结果,一定会比用分子轨道理论或电子配对理论好,因为它更真实的反映了分子的化学性质,同时它也包括了后两者,而以它们为特例。我们得到了分子结合能的表示式,用表示式证明了分子结合能由两部分组成:一部分是键的结合能,另一部分是键与键间的作用能。其次是建议了一种新方法,把在计算化学键相互间的作用能中遇到的一些三中心和四中心积分,还原为容易计算的二中心积分。这方法比以往所用的好,因为它计算比较简单,同时限制性也小。  Black rot of yam bean has been collected from the market in certain localities of Yunnan Province.The diseased tuberroot is characterized by the black dis coloration of the interior tissues without conspicuous external symptoms.The evidence at hand indicates that the infection takes place before the digging time, through the dead main tap roots.It is unlikely that it works in the storage. Hundreds of isolations were made from the diseased tuberroots and one fungus,a species of Pythium,predominated.The... Black rot of yam bean has been collected from the market in certain localities of Yunnan Province.The diseased tuberroot is characterized by the black dis coloration of the interior tissues without conspicuous external symptoms.The evidence at hand indicates that the infection takes place before the digging time, through the dead main tap roots.It is unlikely that it works in the storage. Hundreds of isolations were made from the diseased tuberroots and one fungus,a species of Pythium,predominated.The morphologic and cultural char acters of this causal fungus closely resemble those of Pythium spinosum,described by Sawada in 1927. Inoculations of yam bean seeds were made by sowing them in soils mixed with pure cultures of the causal fungus.It did not cause preemergence of in fection several weeks after inoculation.Elongate black lesions were found on the basal stems.The fungus caused neither dampingoff nor wilt of young seed lings. Healthy tuberroots of yam bean were selected and cleaned.After inserting hyphae and spores beneath the epidermis,they were laid in a moist chamber. Black discoloration of the interior tissues developed in the course of about three weeks.The discolored area enlarged but very slowly.The results of these ino culation experiments indicate that Pythium spinosum Saw.is very weakly parasitic to yam beans. Occasionally,as might be expected,certain other species of fungi were isolated from the diseased tuberroots.Among them were found two other species of Pythium,identified respectively as P.irregulare Buisman and P.intermedium de Bary.However,inoculations of tuberroots of yam bean with these fungi failed to produce the characteristic symptoms. Besides from yam beans,a species of Pythium was isolated from the roots of broad bean(Vicia fabae L.).Despite certain minor morphologic differences,it has been identified as P.spinosum Sawada.However,no cross inoculation ex periments have been conducted.  (1)在云南昆明的市场上,发现有内部组织变黑、但外表没有显明症状的地瓜块根。这个病害,称为地瓜黑心病。(2)地瓜黑心病的病原菌是一种折倒病菌,定名为 Pytlium spinosum Sawada.(3)这个折倒病菌,侵害地瓜的致病力很弱。它不能使地瓜的种子在未出土前枯死,幼苗折倒和蔫萎。它不能使幼株死亡,仅使块茎的内部组织变色。(4)病菌似乎在大田内经主权或茎端侵入块根,发展很慢,迄今还只在收获的块茎内发现这个病害。   << 更多相关文摘 
相关查询  



