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791.
<Emphasis Type="Italic">In situ</Emphasis> generation and detection of methyl radical by voltammetry
The chemistry of free radicals is one of the advanced subjects of fundamental sciences such as biomedicine, environment protection, new energy sources and new material. The detection technique of free radicals is an essential tool for studying free radicals. Methyl radical is one of the representatives of alkyl radicals and the studies on it attract more attention. The current approaches to obtaining methyl radical are based on pulse radiolysis of organic substances that contain the methyl gro… 相似文献
792.
TANG Zhiwen WANG Kemin TAN Weihong LI Jun LIU Lingfeng GUO Qiuping MENG Xiangxian HUANG Shasheng LI Du & LUO Weifang State Key Laboratory of Chemo/Biosensing Chemometrics Institute of Biological Technology College of Chemistry Chemical Engi-neering Hunan University Changsha China Correspondence should be addressed to Wang Kemin 《科学通报(英文版)》2003,48(12):1215-1218
The replication, ligation and repair of nucleic acids are essential life processes that based the survival, pro-creation and evolution of creatures. These interactions involving proteins (enzymes) and nucleic acids have fas-cinated great interest of scientists[1]. The nucleic acids ligation has been revealed that it is catalyzed by ligase and co-enzyme (ATP or NAD)[2—4]. Along with in-depth re-search, the nucleic acids ligation becomes a significant and common tool employed in bioengineerin… 相似文献
793.
The effect of sodium nitroprusside (SNP), a donor of nitric oxide, on meiotic maturation of mouse oocytes was studied by injecting Nw-nitro-L-arginine methyl ester (L-NAME) intra-peritoneal (ip), a nitric oxide synthase inhibitor, or culturing oocytes in the medium supplemented with L-NAME or hypoxanthine (HX) to arrest the spontaneous oocyte maturation in vitro. The results showed that the inhibitory effect of L-NAME by injecting 10 mg/kg ip on extrusion of the first polar body only could be reversed by injecting 2.5 mg/kg SNP with L-NAME simultaneously (P < 0.05). Half an hour later ten mice died when given 10 mg/kg SNP ip. The treatment of some concentrations of SNP (10–7, 10–6, 10–5mol/L) significantly stimulated meiotic maturation to metaphase Ⅱ stages in cumulus enclosed oocytes in the presence of HX. However, other concentrations of SNP (10–8, 10–4, 10–3 mol/L) had no effect on HX-arrested oocyte meiotic maturation. The optimal concentration of SNP on CEOs had no effect on DOs. The dose of 10–3 mol/LL-NAME demonstrated a significant suppression in formation of PB1, but not in GVBD. This inhibition was reversed by the addition of SNP. These results indicated that the physiological levels of NO produced by cumulus cells could stimulate meiotic maturation of mouse oocytes both in vivo and in vitro. 相似文献
794.
795.
796.
采用B3LYP/6-311G**方法对处于优势构象时的巴比妥酸各互变异构体进行了几何全优化和频率计算,CPCM反应场溶剂模型用于水相的计算,得到它们的总能量、零点振动能和溶剂化能.计算结果表明,巴比妥酸在气相中和水相中主要以酮式结构存在.采用相同方法计算并考察了烯醇式与酮式结构进行结构互变质子迁移的2种可能途径:(a)分子内质子迁移;(b)水助质子迁移.结果还表明,途经(b)所需要的活化能较小,氢键在降低反应活化能方面起着重要作用. 相似文献
797.
瑞典皇家科学院将2006年度诺贝尔物理学奖授予马瑟(J.Mather)和斯穆特(G.Smoot)两位教授,表彰以他们为首的学者利用宇宙背景探测器(Cosmic Background Explorer,缩写为COBE)的数据,证实宇宙微波背景辐射的黑体形式.并发现各向异性。这次诺贝尔奖的颁布,肯定了精确宇宙学的一些重要成果。 相似文献
798.
799.
郭志浩 《云南民族大学学报(自然科学版)》2007,16(2):100-104
讨论了含弯矩项u″的四阶边值问题{u(4)(t)=f(t,u(t),u″(t),t∈(0,1)),u(0)=u″(0)=u(1)=u″(1)=0至少存在两个正解.讨论所用的主要工具为锥映射不动点指数定理. 相似文献
800.
Field trial of an HTS filter system on a CDMA base station 总被引:3,自引:0,他引:3
YIN ZheSheng WEI Bin CAO BiSong WANG Xin GUO XuBo ZHANG XiaoPing GAO LongMa PIAO YunLong ZHU MaFeng LIANG Yong WANG Fan H. PIEL B. AMINOV F. AMINOVA M. GETTA S. KOLESOV A. KNACK N. PUPETER D. WEHLER 《科学通报(英文版)》2007,52(2):171-174
This paper presents the field trial results of a high temperature superconductor filter system (HTSFS) in a code division multiple access (CDMA) mobile communication base station (BTS) in Tangshan, China. The center frequency of the HTSFS is 830 MHz with 1.4% fractional bandwidth. The noise figure (NF) of the HTSFS, including connectors and cables, is 0.8 dB. The field trial results show that after the HTSFS was installed in the receiver front-end of a CDMA base station, the transmitting power of handset was decreased by 3.1 dB on average. Up to now, the HTSFS has been running steadily in the base station for more than 22 months, demonstrating the reliability and stability of the system. 相似文献