A characterization ofL n (q) by the normalizers' orders of their sylow subgroups

LetG be a finite group. If for every primer, whereR ₁ Syl _r G andR ₂ Syl _r (L _n (q)), thenG L _n (q).     

荧光法研究Ge—132对苯丙氨酸Maillard反应的抑制作用

哺乳动物体内氨基酸及蛋白质的非酶糖化反应（Ｍａｉｌａｒｄ反应）与糖尿病及其并发症的关系已引起广泛关注［１］，β－羧乙基锗倍半氧化物（Ｇｅ－１３２）具有预防糖尿病和调节糖代谢的作用［２］，研究Ｇｅ－１３２对Ｍａｉｌａｒｄ反应的抑制作用对于开发防治糖尿病...     

内噪声作用下的随机共振算法对弱信号的检测

基于随机共振理论提出了一种简便、有效地检测弱信号的方法。在内噪声协同作用下，通过调节输入噪声信号的大小能较好地提高系统输出信号的信噪比，从而实现检测背景噪声很强的弱信号的目的。应用于模拟信号和实验信号的结果证明了方法是可行的。     

Regioselective hydrosilations. III. The synthesis and polymerization of ambifunctional silicon-containing epoxy monomers

Silicon-containing epoxide compounds bearing Si ? H groups can be readily prepared in high yields by the regioselective rhodium-catalyzed monohydrosilation of α,ω-dihydrogen functional siloxanes and silanes with vinyl epoxides. The remaining Si ? H groups in these compounds can be further selectively hydrosilated with unsaturated epoxides to give a series of unique ambifunctional monomers containing two different epoxide groups in the same molecule. The photopolymerization of these monomers has been studied using analytical techniques including real time infrared spectroscopy and differential scanning photocalorimetry. On photopolymerization, the new monomers yield interesting networks. © 1993 John Wiley & Sons, Inc.     

The key elements of traceability in chemical measurement: agreed or still under debate?

Talking about "traceability" means talking about a "property of the result of a measurement", about "the value of a standard", about "stated references" and about an "unbroken chain of comparisons". It describes by which comparison, and to which other value, the result of a measurement has been obtained, i.e. is "traceable to". It is about the underlying structure of the measurement process of the result of a measurement and therefore about the authority of the result. Since values carried by (certified) reference materials have also been obtained by measurement, the definition of traceability equally applies. Traceability in the context of reference materials is also about the authority of the values carried by the (certified) reference materials and is, therefore, of key importance for the authority of the reference materials themselves. Hence, values of results of measurements constitute part of the traceability chain and their uncertainties are an intrinsic accompanying phenomenon. Uncertainties need a traceability chain against which they can be evaluated, and a traceability chain is an a priori requirement for evaluating the uncertainty budget of a measurement result. An attempt has been made to exemplify "traceability" chains in some types of chemical measurement and to identify the degree of international agreement on the key elements of "traceability". It is concluded that there is less than universal agreement on this issue. The debate should continue in order to arrive at the international understanding and agreement needed, as "traceability" is now being incorporated in the International Organization for Standardization (ISO), the International Laboratory Accreditation Co-operation (ILAC) and in other "guiding" or regulatory documents. It is also the reason why the Institute for Reference Materials and Measurements (IRMM) has taken up the study of the concept in its core programme on Metrology in Chemistry, and why it sponsored the Workshop in Bratislava.     

固相萃取光度法测定饮用水中挥发酚的研究

研究了用Waters Sep-Park-C18小柱固相萃取光度法测定饮用水中挥发酚的方法。水样中经水汽蒸馏分离后的挥发酚，用4－氨基安替比林显色，显色产物可用C18固相萃小柱萃取、乙醇洗脱后用分光光度法测定。方法污染小，操作简便，便于批量样品处理，用于饮用水中挥发酚的测定，结果令人满意。     

5C + 1S] annulation: a facile and efficient synthetic route toward functionalized 2,3-dihydrothiopyran-4-ones

[reaction: see text] A facile and efficient synthetic route toward highly substituted 2,3-dihydrothiopyran-4-ones 2 has been developed via a formal [5C + 1S] annulation of readily available alpha-alkenoyl ketene-(S,S)-acetals 1 with sodium sulfide nonahydrated salt (Na2S x 9H2O) and utilized in the synthesis of 2-(4-chlorophenyl)-6-(morpholin-4-yl)-4H-thiopyran-4-one 5l, an inhibitor of DNA-dependent protein kinase (DNA-PK).     

Structural changes in the monomeric despentapeptide (B30-B26) insulin crystal

Insulin modified by the removal of its 5 B chain C terminal residues is monomeric but remains substantially potent. The crystal structures of the beef and insulin (dpi) with two molecules in the asymmetric unit has been determined by x-ray analysis. The 3-dimensional structure ofdpi proves to be generally similar to that of native molecule in 2Zn insulin. More detailed comparison reveals that the slight differences in the two independent molecules of beefdpi are distributed uniformly throughout the structure in contrast to insulin in 2Zn insulin, where the structural changes are concentrated in specific regions. The loss of symmetry in thedpi crystal appears to be the inability of the A9 serine to pack effectively in the C2 cell. The efficient packing of the sheepdpi molecule whose crystal structure has also been determined and where A9 is glycine supports this conclusion.     

Physical and chemical properties of a durably efficacious ammonium bicarbonate as a fertilizer and its yield-increasing mechanism

A new fertilizer of cocrystal type,known as durably efficacious ammonium bicarbonate (DEAB),has been developed by adding a certain amount of dicyandiamide (DCD) as an ammonia-stabilizing agent to ammonium bearbenate(AB)during the process of its production.As compared with AB,DEAB was found to have a reduction of direct volatilization loss by 53%,a fertilizer availability period prolonged from 35-45 to 90-110 d,and an increase in the rate of nitrogen in fertilizer being utilized by 5.9%-10.2%,and a saving of the amount of fertilizer to be ap-phed by 20%-30% for the same level of yield,or an increase of the crop yield by over 10% for the same level of ni-tregen fertilization;in addition,it was found to show usually a function of promoting the crop to early mature.It can be apptied as basal dressing all in one time to soil and thus also used as a labour-saving and crop yield-increasing fertil-izer for is non-mtertillage,plastics film covering and water-saving agriculture