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麦斛细胞毒活性成分研究 总被引:5,自引:0,他引:5
利用硅胶、聚酰胺柱层析等分离方法, 从麦斛全草的乙醚萃取物中分离得到4个化合物, 经化学方法和光谱分析(UV, IR, NMR, MS)鉴定为3,4,7-三羟基-2-甲氧基菲(1), 2,5-二羟基-4-甲氧基菲(2), eugenitin (3)和2,5-二羟基-4-甲氧基-9,10-二氢菲(4), 其中1为新化合物. 采用MTT法分别测得化合物1和2对体外培养的人急性髓性白血病细胞和人肝癌细胞增殖的抑制活性, 并分别考察了增敏剂葛根素对化合物1和2增殖活性的协同作用. 相似文献
123.
Radiochemical neutron activation analysis (RNAA) has been used for the determination of eight rare earth elements (La, Ce, Nd, Sm, Eu, Tb, Yb, and Lu) in two Chinese certified reference materials (CRM), GBW 08503 (wheat powder) and GBW 09101 (human hair). These determinations are important for possible certification of the above mentioned ultra-trace elements, so far not certified. A simple one-step (REE)F3 precipitation was used. Chemical yields were determined for all relevant elements by means of tracer experiments. The two CRM were also analyzed by inductively coupled plasma-mass spectrometry (ICP-MS) to compare the merits and draw-backs of these two major trace analytical techniques for these particular elements. RNAA was proven to be a reliable technique for ultra-trace analysis, especially in the certification of some ultra-trace elements. 相似文献
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Cao Lei S. Landsberger S. Basunia Yu Tao 《Journal of Radioanalytical and Nuclear Chemistry》2004,261(1):87-94
Airborne particulate matter (APM) was collected in coarse fraction and in PM2.5 during spring of 2002 in Beijing suburban sampling site by Gent SFU sampler. More attention has been paid to the special
“events” such as dust, storm and haze. Taking advantage of the combination of thermal or epithermal neutron irradiation with
Compton suppression spectrometer system, twenty elemental (Al, Si, Ca, K, Dy, Cu, I, In, Ba, W, Sn, Sb, As, Ti, Br, V, Mn,
Cl, Na, Zn) concentration were determined. Among them, several key trace elements that cannot be accomplished by the traditional
neutron activation analysis (NAA) were determined. The analysis of trace elemental concentration in PM2.5 shows that the anthropogenic elements such as As, In, Sn, Sb have different trends than crustal elements. The back-trajectories
of the high concentration anthropogenic pollution elements revealed their source region. Six potential sources were resolved
by positive matrix factorization (PMF), two area type and four source type, as soil, limestone quarry, crop burning and mixture
of residue motor and coal burning sampling sites. Taking into account of everyday air particle back trajectories, source compositions
together with source regions were also identified.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
125.
The design for the deployment of artistic statues in an exhibition area comes from the designer's experience, and whether such a design is adequate having no simple applicable criterion. The proposed model, deploying statues (DSs) model, not only applies the fractal dimension to measure the spatial complexity as its objective but also considers the traffic flow zone, the number of DSs, the average diameter of the statue, and the minimum allowable distance of adjacent artistic statues to arrange the spatial configuration in an exhibition area. The minimal complexity (fractal dimension) is mainly focused on because exhibiting designers deem that the spatial simplicity of an exhibition area leads to comfortable vision for a visitor. Indeed, this paper describes an applicable aspect of fractals. A computational intelligence written in Fortran Program to perform the spatial arrangement of artistic statues in an exhibition area is provided, and its adaptability has been explored by pilot tests of benchmark cases. Then, a case study through visual reality deployment for the Hosanna Museum at Chiayi Taiwan is followed. This study indeed provides a valuable tool in conducting the pre-stage of thinking process for exhibiting designers in deploying exhibits. 相似文献
126.
Xianyi Li 《Journal of Mathematical Analysis and Applications》2007,334(1):528-533
By making use of inclusion theorem, we show in this paper the existence of solutions with a single semicycle for a general second-order rational difference equation. As a corollary, our results positively confirm Conjectures 4.8.3 and 5.4.6 in [M.R.S. Kulenovic, G. Ladas, Dynamics of Second-Order Rational Difference Equations, with Open Problems and Conjectures, Chapman and Hall/CRC, 2002]. 相似文献
127.
《Applied Mathematics Letters》2003,16(7):1039-1045
Oscillation properties of the solutions of a class of odd order neutral delay parabolic differential equations are investigated via the method of differential inequalities. 相似文献
128.
DNA solution of a graph coloring problem 总被引:9,自引:0,他引:9
The graph-theoretic parameter that has probably received the most attention over the years is the chromatic number. As is well-known, the coloring problem is an NP-Complete problem. In this paper, it has been solved by means of molecular biology techniques. The algorithm is highly parallel and has satisfactory fidelity. This work shows further evidence for the ability of DNA computing to solve NP-Complete problems. 相似文献
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In this paper, we give a classification of nonoscillatory solution of a second-order neutral delay difference equation of the form $$\Delta ^2 (x_n - c_n x_{n - \tau } ) = f(n, x_{g_1 (n)} ,..., x_{g_m (n)} ).$$ Some existence results for each kind of nonoscillatory solutions are also established. 相似文献