25,26,27-三失碳-B-高-7-氧-6-酮-5α-胆甾-3α,24-二醇的合成

本文报道以3α-羟基-6-羰基-5α-胆烷酸甲酯(3)为原料经六步反应合成了油菜甾醇类似物25,26,27-三失碳-B-高-7-氧-6-酮-5α-胆甾-3α,24-二醇(9a).总产率14%.9a的促进植物生长作用是24-表油菜甾醇内酯的60%.     

控制异丁烯阳离子聚合终止方式的新方法—活性中心转化法

控制异丁烯阳离子聚合终止方式的新方法──活性中心转化法曹宪一，王强，武冠英（北京化工大学高分子材料研究所，北京，１０００２９）关键词异丁烯，阳离子聚合，活性中心转化自八十年代中期Ｈｉｇａｓｈｉｍｕｒａ及Ｋｅｎｎｅｄｙ等人陆续发现乙烯基醚类单体及异丁烯...     

光导池吸光度表达式的推导与计算──小矩形横截面入射光束

光导池吸光度表达式的推导与计算──小矩形横截面入射光束刘占军,王云飞（中国科学技术大学应用化学系,合肥,２３００２６）关键词光导池,全反射长毛细管池,吸光度表达式魏磊等［１］分别提出全反射长毛细管池（ＴＲ－ＬＣＣ）中按子午光线和螺旋光线反射行进时的好...     

Studies on HEPES Stabilizing M Intermediate of Bacteriorhodopsin

ＳｔｕｄｉｅｓｏｎＨＥＰＥＳＳｔａｂｉｌｉｚｉｎｇＭＩｎｔｅｒｍｅｄｉａｔｅｏｆＢａｃｔｅｒｉｏｒｈｏｄｏｐｓｉｎＦＵＸｕｅ－ｑｉ￣１,ＬＩＺｈｅｎｇ－ｑｉａｎｇ￣２,ＷＡＮＧＪｉｎ－ｄｕｉ￣１,ＷＡＮＧＢａＯ－ｈｕｉａ,ＬＩＢｏ－ｆｕ￣２ａｎｄＬＩ...     

Studies on Colloidal Properties of Mixed Metal Hydroxide－Clay Aqueous Suspension

ＳｔｕｄｉｅｓｏｎＣｏｌｌｏｉｄａｌＰｒｏｐｅｒｔｉｅｓｏｆＭｉｘｅｄＭｅｔａｌＨｙｄｒｏｘｉｄｅ－ＣｌａｙＡｑｕｅｏｕｓＳｕｓｐｅｎｓｉｏｎＮＯＵｗａｎ－ｇｕｏ；ＺＨＡＮＧＣｈｕｎ－ｇｕａｎｇ；ＳＵＮＤｅ－ｊｕｎ；ＨＡＮＳｈｕ－ｈｕａａｎｄＷＡＮＧ...     

STUDY ON TPR OF NICKEL OXIDE CATALYSTS CALCINED AT HIGH TEMPERATURES

TPR technique has been used, to investigate the reducibilities of three types of nickel oxide catalysts calcined in air between 650℃and 1050℃: NiO/Al2O3, NiO/MgAl2O4and NiO/(CaO, MgO) · A12O3· xSiO2. The results indicate that the TPR peaks of all the catalysts were shifted toward high temperature and peak areas were gradually reduced with increasing calcination temperature. Particularly, the main TPR peaks almost disappeared at 1050℃-It was also observed that NiO/(CaO, MgO)· Al2O3 · xSiO2 catalyst was the easiest to be reduced of these catalysts, and there was a small shoulder peak before the main peak for each catalyst. Examination of these catalysts by XPS showed that there were two forms of nickel oxides on support surface .     

EFFECTS OF K_2O AND MnO PROMOTERS ON THE PRODUCTION OF LIGHT ALKENES VIA SYNGAS OVER Fe/SILICALITE-2 CATALYST I.ACTIVITY OF K-Fe-MnO/SILICALIT-2 CATALYST

The activity and the selectivity to light alkenes of silicalite-2 (Si-2) zeolite supported F'e catalyst tor CO hydrogenation can he improved obviously with the addition of K2O and MnO promoters. The results of CO hydrogenation, CO-TPD, CO/H2-TPSR, C2H4/H2-TPSR and C2H4/H2 pulse reaction over K-Fe-MnO/Si-2 catalysts clearly show that the K2O additive into Fe-MnO/Si-2 catalyst leads to a remarkable increase in both the capacity and strength of the strong CO ad-species that will produce much more |Cad| via their disproportionation at higher temperatures. This results in an increase in the CO conversion and the selectivity to light olefins, and a decrease in CH4 formation. Moreover, K2O can suppress the disproportionate of C2H4 that occurs during the reaction as a side-reaction Meanwhile, the MnO promoter mainly prohibits the hydrogenation of C2H4 and C3H6, which is favorable to enhancing the selectivity to C2H4 and C3H6 and decreasing the formation of C2H6, and C3H8. It is also of interest that MnO has har     

PRODUCTION OF LIGHT ALKENES FROM SYNGAS OVER Fe-MnO CATALYST SUPPORTED ON IIA METAL OXIDE

The alkene selectivity of CO hvdrogenation over Fe-MnO catalystis improved obviously by using NA metal oxide as catalyst support.Bettercatalytic pertformance of catalyst Fe-MnO/MgO can be achieved withaddition of LA metal as promoter.The selectivity is insensitive totemperature.but not to syngas space velocity.Two kinds of coking(I and Ⅱ)will form over the catalyst during CO hydrogenation.lt is interesting thatcoking(I)is favorable for production of light alkenes while cokiing(lI)is not.Other more.LA metal oxide supported Fe-MnO catalyst is able to inhibit thesecondary reactions of ethylene and hydrogenation of propylene.which isfavorable for the formation of light alkenes.     

石墨化碳黑净化柱结合HPLC－PDA和LC－MS/MS快速检测苹果汁中展青霉素

基于石墨化碳黑材料制备了一种固相萃取柱（GCB柱）,结合高效液相色谱－二极管阵列检测法（HPLC－PDA）和液相色谱－串联质谱法（LC－MS/MS）评估了GCB柱和4种商业化固相萃取柱（RetainAX、PAX、MAX和HLB）的净化效果,并对澄清型苹果汁中影响展青霉素准确定量的杂质进行了分析。结果发现,苹果汁经上述5种净化柱净化后,大大降低了杂质干扰,色谱图、信噪比和基质效应显著改善。其中,GCB净化为HPLC－PDA分析提供了理想的色谱图,为LC－MS/MS分析提供了可接受的基质效应（-14%）、优于HLB净化的色谱图以及与RetainAX净化相当的信噪比。建立的稳定同位素稀释－液相色谱－串联质谱法（SIDA－LC－MS/MS）可以克服基质效应和净化损失对检测结果准确性的影响。采用HPLC－PDA和SIDA－LC－MS/MS分析时,GCB净化比HLB净化的方法更灵敏;MAX、HLB和GCB净化均能得到较好的回收率（82%~102%）和较小的相对标准偏差（≤9%）。所开发的GCB净化方法仅需上样和洗脱2步,且在重力作用下过柱仅需10min,比其他固相萃取净化更简单快捷,净化能力良好。实际样品经GCB柱净化和HPLC－PDA、SIDA－LC－MS/MS分别分析,展青霉素的平均含量为34μg·kg^-1。GCB柱较好的净化效果和较低的使用成本将有助于其在展青霉素常规检测中的广泛应用。     

REE AND Sr, Nd, Pb ISOTOPIC GEOCHEMISTRY OF HUANGYISHAN BASALT, KUANDIAN, LIAONING, NORTHEAST CHINA

In the light of major element geochemistry, mineral chemistry and REE and isotopic data, the small but apparent isotopic differences between the Cenozoic volcanic rocks east and west of the Tancheng-Lujiang fault are believed to be caused by the mixing and metasomatism of crustal and mantle material in tho mantle source region in response to Pacific plate subduction. The presence of phlogopite and pargasite in mantle xenoliths lends strong support to mantle metasomatism.