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1.
硫酸皮肤素寡糖的分离与制备 总被引：2，自引：0，他引：2
利用软骨素酶 ABC (Chondroitinase ABC,EC4 .2 .2 .4 )对硫酸皮肤素 (Dermatan Sul-fate,DS)进行控制降解。对得到的混合寡糖首先采用低压凝胶渗透色谱 (L PGPC)进行分级 ,然后对每一组分再利用强阴离子交换高压液相色谱 (SAX- HPL C)进行分离 ,最终制备出聚合度为 2 ,4 ,6 ,8,10 ,12的寡糖纯品。寡糖纯度采用 SAX- HPL C,毛细管电泳 (CE)以及聚丙烯酰胺凝胶电泳(PAGE)进行检验 ,结构采用电喷雾离子化质谱 (ESI- MS)以及核磁共振波谱 (NMR)技术确定 相似文献
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I. V. Chilingarian P. Prugniel O. K. Sil'chenko V. L. Afanasiev 《Monthly notices of the Royal Astronomical Society》2007,376(3):1033-1046
We present the first 3D observations of a diffuse elliptical galaxy (dE). The good quality data (S/N up to 40) reveal the kinematical signature of an embedded stellar disc, reminiscent of what is commonly observed in elliptical galaxies, though similarity of their origins is questionable. Colour map built from Hubble Space Telescope Advanced Camera for Surveys (ACS) images confirms the presence of this disc. Its characteristic scale (about 3 arcsec =250 pc) is about a half of galaxy's effective radius, and its metallicity is 0.1–0.2 dex larger than the underlying population. Fitting the spectra with synthetic single stellar populations (SSP), we found an SSP-equivalent age of 5 Gyr and nearly solar metallicity [Fe/H] =−0.06 dex. We checked that these determinations are consistent with those based on Lick indices, but have smaller error bars. The kinematical discovery of a stellar disc in dE gives additional support to an evolutionary link from dwarf irregular galaxies due to stripping of the gas against the intracluster medium. 相似文献
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O.K. Sil'chenko 《Astrophysics and Space Science》1999,265(1-4):389-390
The results of magnesium-to-iron ratio estimates are presented for the nuclei and central bulges of disk galaxies. A great
variety of behaviours is found: the nuclei have solar Mg/Fe ratio or are Mg-overabundant, the bulges can be more or less Mg-overabundant
than the nuclei. But the most bulges have nearly solar Mg/Fe ratios, irrespective of their luminosity.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Leningrad State University; P. K. Shternberg State Astronomical Institute. Translated from Astrofizika, Vol. 33, No. 2, pp. 157–168, September–October, 1990. 相似文献
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A.M. Fridman O.V. Khoruzhii V.V. Lyakhovich V.S. Avedisova O.K. Sil'chenko A.V. Zasov A.S. Rastorguev V.L. Afanas'iev S.N. Dodonov J. Boulesteix 《Astrophysics and Space Science》1997,252(1-2):115-131
General ideas, as well as experimental and theoretical efforts concerning the prediction and discovery of new structures in the disks of spiral galaxies – giant anticyclones - are reviewed. A crucial point is the development of a new method to restore the full vector velocity field of the galactic gas from the line-of-sight velocity field. This method can be used to get self-consistent solutions for the following problems: 1) determination of non-circular velocities associated with spiral-vortex structure; 2) determination of fundamental parameters of this structure: pattern speed, corotation radius, location of giant anticyclones; 3) refinement of galactic rotation curves taking into account regular non-circular motion in the spiral density wave, which makes it possible to build more accurate models of the mass distribution in the galaxy; 4) refinement of parameters of the rotating gaseous disk: inclination angle, center of rotation and position angle of the major dynamical axis, systematic velocity. The method is demonstrated using the restoration of the velocity field of the galaxy NGC 157 as an example. Results for this and some other spiral galaxies suggest that giant anticyclones are a universal property of galaxies with grand design structure. 相似文献
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In this paper we discuss observational and theoretical arguments in favour of hypothesis on nomad life of active nuclei inside and outside galaxies as well as its consequences. It may be the anisotropic collapse of a supermassive star, or the disruption of a supermassive binary system after the collapse of one companion that would give birth to such nuclei. We predict the existence of veritable quasi-stellar active objects without any ghost gagalies. 相似文献
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Ryder Zasov McIntyre Walsh & Sil'chenko 《Monthly notices of the Royal Astronomical Society》1998,293(4):411-428
We present the results of a new H i , optical, and Hα interferometric study of the nearby spiral galaxy NGC 157. Our combined C- and D-array observations with the VLA show a large-scale, ring-like structure in the neutral hydrogen underlying the optical disc, together with an extended, low surface density component going out to nearly twice the Holmberg radius. Beginning just inside the edge of the star-forming disc, the line of nodes in the gas disc commences a 60° warp, while at the same time, the rotation velocity drops by almost half its peak value of 200 km s−1 , before levelling off again in the outer parts. While a flat rotation curve in NGC 157 cannot be ruled out, supportive evidence for an abrupt decline comes from the ionized gas kinematics, the optical surface photometry, and the global H i profile. A standard 'maximum-disc' mass model predicts comparable amounts of dark and luminous matter within NGC 157. Alternatively, a model employing a disc truncated at 2 disc scalelengths could equally well account for the unusual form of the rotation curve in NGC 157. 相似文献
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海南五指山市30 a生枫香次生林结构和树种多样性研究结果表明:乔木层共有64种树种,隶属于27科47属,枫香是优势树种;Shannon-Wiener指数、Simpson指数和Pielou指数分别为2.80、0.84和0.67。乔木层可分出2个亚层,第I亚层有27种树种,Shannon-Wiener指数、Simpson指数和Pielou指数分别为1.65、0.56和0.50,枫香是该亚层的优势种,重要值为197.51%,其他只有中平树的重要值(16.10%)超过10.00%;第II亚层有58种树种,Shannon-Wiener指数、Simpson指数和Pielou指数分别为3.18、0.93和0.78;重要值较大的有枫香、犁耙柯、中平树和黄牛木,分别为52.58%、33.06%、26.55%和25.29%。林分直径分布呈"反J型";根据"种-面积"关系导出群落最小调查面积为2 000 m2。林分密度为3 416株/hm2,平均胸径为13.5 cm,平均高为8.7 m,蓄积量为271.1 m3/hm2。 相似文献