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41.
使用美国甚大天线阵(VLA).对Markarian 8星系进行了多频观测.多频VLA观测表明,Markarian 8星系有三个主要的射电子成份,它们浸在一个弥漫的星系包层中.包层的射电谱是陡的非热谱.本文根据VLA观测确定了包层的物理参量,并讨论了包层中相对论性电子的可能起因.本文估计了包层非热辐射所要求的超新星爆发率.  相似文献   
42.
A novel method of fabricating composite mosaic membranes was studied on the basis of interracial polymerization (IP) by coating a thin selective layer onto the surface of a micro-porous hollow-fiber membrane, in which, 2,5-diaminobenzene sulfonic acid was used as one monomer of the IP reaction, and a mixture of trimesoyl chloride (TMCI) and 4-(chloromethyl) benzoyl chloride as the other monomer. Through the IP reaction a thin selective layer with negatively charged groups could be first formed on the polyethersulfone (PES) support membrane. Then trimethylamine solution was introduced to modify the IP layer through a quaternization reaction. Thus the selective layer of this composite membrane contained both negatively charged and positively charged groups to perform the mosaic functionality. Characterization of the composite mosaic membranes was carried out through permeation experiments using different inorganic salts and dyes. The experimental results showed that the membranes could permeate both mono- and bi-valent inorganic salts, but reject larger organic molecules. Such a mosaic membrane is potentially useful for the separation of salts from water-soluble organics, especially in dye and textile industries.  相似文献   
43.
本文讨论圆形区域内芽虫分布模型,特别研究了芽虫与天敌接触时产生与避免outbreak状态的可能性。  相似文献   
44.
Since tungsten was chose as the divertor tiles of 1TER, the investigation of tungsten and its coating as plasma facing material (PFM) have been paid more attentions by fusion scientists all over the world. Recent years, tungsten coatings have been successfully  相似文献   
45.
IntroductionThe interest in polyoxometalates that are widelyused in medical chemistry, catalyst reactions, and ma-terial sciences stems from their complicated aggregatesformed by means of corner-, edge- and face-sha-ring[1—4]. The exploitation of new str…  相似文献   
46.
The present paper deals with the long-time behavior of a class of nonautonomous retarded semilinear parabolic differential equations. When the time delays are small enough and the spectral gap conditions hold, the inertial manifolds of the nonautonomous retard parabolic equations are constructed by using the Lyapunov-Perron method.  相似文献   
47.
The operator sets, which are the subject of this paper, have been studied in many papers where, under different restrictions on the generating operators, convexity, compactness in the weak operator topology, and nonemptiness were proved for sets of different classes under study. Then the results obtained were used in these papers to solve several applied problems. Namely, they played the key role in establishing the dichotomy of nonautonomous dynamical systems, with either continuous or discrete time. In the present paper, we generalize and sharpen the already known criteria and obtain several new criteria for convexity, compactness, and nonemptiness of several special operator sets. Then, using the assertions obtained, we construct examples of sets of the form under study which are nonconvex, noncompact in the weak operator topology, as well as empty, and are generated by "smooth" operators of a special class. The existence problem for such sets remained open until the authors of this paper announced some of its results.  相似文献   
48.
The thermal conduction and Navier-Stokes equations are usedto obtain the stress field generated by a chopped electron beam incident ona disk sample.The piezoelectric equation is then used to obtain the out-put signal of the transducer coupled to the sample.The results lead to aconsideration of the signal generation mechanism and spatial resolution inscanning electron acoustic microscopy(SEAM).It is shown that atime-variant heat source generated both a thermal wave and an acousticwave simultaneously,and thermal-to-acoustic wave mode conversion oc-cured on the boundary surfaces depends on the amplitudes and the gra-dients at boundary surfaces of both heat source and thermal waves.It isargued that the spatial resolution of a imaging system operated in thenear field,such as SEAM and thermal wave microscope,is dependent onthe distance between the heat source and scatterer and,at best,the lateralresolution in SEAM is of the order of the diameter of the focal spot ofthe electron beam.  相似文献   
49.
本文讨论了高效液相色谱死体积的定义和如何以吉布斯热力学理论为基础对其测定。推荐的热力学理论方法能应用于任何一种液相色谱方法,如正相、反相、离子交换、甚至体积排斥色谱。提出了一种能在整个浓度范围内准确计算流动相组分干扰峰死体积的方法。对某些化合物容量因子出现负值也作了解释。  相似文献   
50.
Suppose that we want to approximate fC[0,1]by polynomials in P_n,using only itsvalues on X_n={i/n,0≤i≤n}.This can be done by the Lagrange interpolant L_n f or theclassical Bernstein polynomial B_n f.But,when n tends to infinity,L_n f does not converge to fin general and the convergence of B_n f to fis very slow.We define a family of operators B~(k)_n,n≥k,which are intermediate ones between B(0)_n=B~(1)_n=B_n and B~(n)_n=L_n,and we studysome of their properties.In particular,we prove a Voronovskaja-type theorem which assertsthat B~(k)_n f-f=0(n~(-[(k+2)/2))for f sufficiently regular.Moreover,B(k)_n f uses only values of B_n f and its derivaties and can be computed by DeCasteljau or subdivision algorithms.  相似文献   
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