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The problem of reconstruction of the function from the data of its integrals over half circles A ? H with centers at the diameter of H is studied.


The location of rescue centers is a key problem in optimal resource allocation and logistics in emergency response.


A systematic depiction centers on the designs of material structure, device structure, photolithography mask, fabrication of device and the measurement and analysis of parameters.


The Hough transform and the least squares method are used to extract the stable scattering centers and their scattering coefficients.


The genus has three modern distribution centers: South Europe, North America and East Asia.

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 Occurrence of sporadic diseased plant centers during or after the bloomingperiod is considered as reliable indication of the current year's forthcomingoutbreak of late blight in a potato farm. Incubation period of each secondary infection being about 4 days,is ratherconstant during the blight epiphytotic season under Chahar conditions.The timeinterval between the appearance of initial diseased plant centers to final totalblight in a potato field varies greatly,however,not only from locality to localitywith... Occurrence of sporadic diseased plant centers during or after the bloomingperiod is considered as reliable indication of the current year's forthcomingoutbreak of late blight in a potato farm. Incubation period of each secondary infection being about 4 days,is ratherconstant during the blight epiphytotic season under Chahar conditions.The timeinterval between the appearance of initial diseased plant centers to final totalblight in a potato field varies greatly,however,not only from locality to localitywith different climatic conditions but also from field to field under similarclimatic conditions.Our data record a range of 1842 days.Circumstantial evidences indicate that this variation is due,on the one hand,to the rainfall whichinfluences the amounts of sporulation and the frequency of penetration of thepathogene,and on the other hand,to cultural and other factors that determinethe vigor and the rate of aging of the plant itself. Actual counts of lesions formed from secondary infection in the early periodof the spread of the disease in a potato field,reveal that their distribution bearsdirect relation with the direction of the prevailing wind.It is estimated that over90% of spores fall within a rectangle of 800 sq.m.around a diseased plantcenter along the loci of wind directions. On the basis of possible function of absorbed copper ions in the enhancementof plant resistance to late blight,field experiments have been conducted by using0.1  0.2% copper sulfate solutions as spray.Results show that spraying 23 timesat 710 days' interval,started soon after the appearance of diseased plant center,gives remarkable control of late blight and corresponding reduction of loss inyield.The copper sulfate spray,though less effective and stable in comparisonwith the bordeaux spray,has the advantage of being more economical and easierto apply.Further experiments with the pu:pose of modifying and improving themethod are in progress.  從馬鈴薯的開花期起可能在田间出现的晚疫病中心病株是本田當年病害即將大量發生的重要標誌。每次再侵染的潛育期,在張家口壩下地區的氣候下,大約4天。從病害的最初發現到全面枯死所經過的日期囚種種外界環境條件而有很大的差別,我們所觀察到的是18—42天。根據調查资料來推測,一方面,促進病菌孢子形成数量和侵入數量的雨水,另一方面,决定植株衰老速度的栽培條件,是這種差別的主要原因。田間再侵染所形成的病斑之分佈情况說明病菌孢子的傳播与風向有直接的關係。估計90%以土的孢子落在中心病株附近順着風向的800平方米的長方形面積上。根據馬鈴薯地上部吸收銅素以提高共抗病力的可能性,利用0.1—0.2%硫酸銅溶液作為噴射劑,在田间中心病株發現的時期開始每隔7—10天喷射共2—3次,可以顯著地降低晚疫病的為害,提高產量。這個方法在共效驗及穩定性上不如波爾多液,在藥劑費用的節省及施用的方便上則勝之?椒ǖ母牧己吞岣哒谶M一步研究中。  The fore foot of the mole is three times larger than its hind foot. Serialsections of the spinal cords of two adult moles were prepared for a comparativestudy of the motor centers of the fore and hind legs in the cervical and lumbar enlargements. The magnitude of the motor cells in the anterior horn of the cervicalenlargement (centers of leg muscles), wheh taken collectively, is 2.52.8 timesthat of the lumbar enlargement. The motor cells in the posterior part of theanterior horn (posterolateral... The fore foot of the mole is three times larger than its hind foot. Serialsections of the spinal cords of two adult moles were prepared for a comparativestudy of the motor centers of the fore and hind legs in the cervical and lumbar enlargements. The magnitude of the motor cells in the anterior horn of the cervicalenlargement (centers of leg muscles), wheh taken collectively, is 2.52.8 timesthat of the lumbar enlargement. The motor cells in the posterior part of theanterior horn (posterolateral and retroposterolateral columns,centers of footmuscles) of the cervical enlargement, if compared separately, are 3.44.0 timesthose of the lumbar enlargement. The two columns innervating the foot muscles contain enormous cells,break into subcolumns and thrust posterolaterally to form a new "horn" whichis even larger than the original anterior horn on many levels. The upper part of the retroposterolateral column (centers of digital muscles) is better developed than the lower part. With cells exceedingly hypertrophied and subcolumns well differentiated, the upper end seems in control ofthe huge big toe (and also partially of the largesized second and third toes).while the motor center of the little toe is apparently located at the lowerend. The immense bulk of the fore leg of the mole is associated with a corresponding differentiation of its spinal centers. The development of a peripheralpart is correlated with a commensurate structure on the central side.  鼹鼠的前足约为後足的3倍。本研究用二个成长鼹鼠的脊髓,作连续染片,比较颈腰膨大部中前後肢的运动中枢的形态。若综合比较颈腰膨大部前角的运动细胞(肢肌的中枢)的数量,颈部约当腰部的2.5—2.8倍。若单独比较前角后部的运动细胞(後外侧柱和後後外侧柱——足肌的中枢)的数量,颈部竟大到腰部的3.4—4.0倍。支配足肌的二柱细胞巨大,分出亚柱,胞团外拓,形成一个新角;有些阶段,它更大过原来的前角。後後外柱的上端比下端发展得多。上端细胞巨大,亚群明显,似主管奇大的踇趾(和二、三趾);小趾的中枢似在下端。鼹鼠前肢的(厂龙)大联系脊髓中枢的分化。周缘部的发展程度与中枢部的形态是相系的。  Although James and Coolidge (1933) solved the molecular hydrogen problem in almost complete agreement with experiment by using a 13term 2electron eigenfunction, his method can hardly be applied to more complex molecules. For this and other reasons (Coulson, 1938), it is still desirable to obtain a good oneelectron eigenfunction, i.e., molecular orbital, for the hydrogen molecule. The best molecular orbital treatment available in the literature was given by Coulson (1938), who used a trial eigenfunction in... Although James and Coolidge (1933) solved the molecular hydrogen problem in almost complete agreement with experiment by using a 13term 2electron eigenfunction, his method can hardly be applied to more complex molecules. For this and other reasons (Coulson, 1938), it is still desirable to obtain a good oneelectron eigenfunction, i.e., molecular orbital, for the hydrogen molecule. The best molecular orbital treatment available in the literature was given by Coulson (1938), who used a trial eigenfunction in elliptical coordinates involving 5 parameters and obtained 3.603 eV for the binding energy of H_2, which is to be compared with the ex perimental value of 4.72 eV. In the present investigation we have proposed a new type of trial eigenfunction for the molecular orbital: (1) with p = centers a, b, g, c, d,…… i = electron 1 or 2 (2) where the p's are centers along the bond axis ab (Fig. 1). In this simple problem both the Fock and Hartree methods yield the same result. The molecular orbital ψ must satisfy the following integral equation: (3) where ε is the energy of the molecular orbital, F is the Fock operator which is equal to H+G(1), while H is the oneelectron Hamiltonian operator: H = 1/2▽~21/r_a1/r_b (4) and G(1) is the interaction potential (5) Substituting (1) into (3), we obtain the linear combination coefficients c_p, which must satisfy the following secular equation: (6) where is the solution of the secular determinant and The F_(pq)'s are not at first known, but depend upon the c_p's. A method of successive approximation must therefore be adopted. A set of c_p values may be assumed, the F_(pq)'s calculated, the secular determinant (7) solved, and a new set of c_p values found. This process is repeated until a "selfconsistent" set of c_p values is obtained. The above procedure was first proposed by Roothaan (1951), not for H_2 but for more complex molecules. It was called by him the "LCAO SCF (linear combination of atomic orbitals selfconsistent field) method". The new feature of the present investigation is that we not only use LCAO but also LCNAO (linear combination of nonatomic orbitals, such as x_g, x_c, x_d, …). The order of secular determinant (7) may be reduced to half if we replace the eigen functions x_a, x_b .... by their symmetrical and antisymmetrical linear combinations x_a + x_b and x_ax_b. Numerical calculations have been carried out both for the three and the twocentered molecular orbitals. The threecentered molecular orbital is (10) (11) where S_(ab) and S(ag) are the overlapping integrals between x_a and x_b, and between x_a and x_g respectively. The parameters a and g have 'been obtained to give minimum energy by the method described above. They are a=l.190, g=0.22, and the binding energy is 3.598 eV, which is almost as good as that obtained by Coulson (3.603 eV) using a trial function of 5 parameters. The twocentered molecular orbital is (12) (13) which gives a maximum binding energy of 3.630 eV for a=1.190 and R~(ac)=R(bd)=0.105 (Fig. 1). This result is 'better than Coulson's. If we allow different values for the exponent α in x_a and x_g in equation (11), or if we use a fourcentered molecular orbital, such as ψ=a(x_a + x_b) + b(x_c + x_d) with four parameters, namely α_a=α_b, α_c=α_d, R_(ac)=R_(bd) and the ratio b/a, it is possible to obtain a still better result. Extension of the present method to the treatment of more complex molecules is now under investigation.  (1)討論了用自洽勢場多中心分子軌道法來處理H_2分子的一般方法。 (2)用僅含兩個參變數三中心分子軌道進行了具體計算,求得H_2分子的結合能為3.598eV,接近於Coulson用五個參變數的雙中心分子軌道所得的結果(3.603eV)。 (3)用不在原子核上的兩中心的分子軌道求得H_2分子的結合能為3.630 eV,此上述結果為好。並指出如用不同的α值和四個或四個以上中心的分子軌道,很有可能得到更好的結果。以上處理方法有可能推廣到比H_2更為複雜的分子。   << 更多相关文摘 
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