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排序方式: 共有82条查询结果,搜索用时 31 毫秒
61.
新的19-降海绵烷二萜的分离及结构确定 总被引:2,自引:0,他引:2
从海洋海绵Spongiazimoccaaubspeclesirregularia中分离到一种新的19-降海绵烷二萜(ZimoclactoneA,1)和胆甾-5,7-二烯-3β-醇,化合物1的化学结构和立体化学通过波谱方法和X射线单晶衍射分析确定,化合物1对P388肿瘤细胞具有中等程度的细胞毒活性. 相似文献
62.
Complete fusion cross sections have been measured for 12C+159Tb and 12C+165Ho reactions by using K-X rays of evaporation residues with Si(Li)spectrometer.The half-lives of evaporation residues and its yield distributions as a function of incident energy have also been obtained.The experimental values for the complete fusion cross section were compared with the theoretical ones. 相似文献
63.
利用固体高分辨核磁共振技术对 4个国家的 6个煤样品进行了研究 ,测得了 1 2个结构参数 ,并与中国煤的参数进行了比较 ,同时进行了煤的谱编辑实验 ,测量了煤的15 N核磁共振谱 . 相似文献
64.
ZHANG Li JIN Gen-Ming ZHAO Jin-Hua YANG Wei-Fan YANG Yong-Feng ZHAO Zhi-Zheng ZHENG Ji-Wen SUN Xiu-Rong LI Zong-Wei QIN Zhi WANG Ji-Cheng GUO Guang-Hui 《中国物理C(英文版)》1992,16(8):767-768
The new neutron-rich isotope 208Hg has been identified for the first time from the reaction products in fully-stopping thick nat.Pb target bombarded by 30MeV/u 12C beam provided by the Heavy Ion Research Facility in Lanzhou.Assignment of the nuclide 208Hg was based on the measurements of the deacy γ energy and halflife of its daughter 208Ti,which was grown up with 208Hg β-deacy.The half-life of 208Hg β-deacy was determined to be 42+23-12 min.The average production cross section of 208Hg over the incident energy region from Coulomb barrier to 30MeV/u is found to be 1.1±0.5μb. 相似文献
65.
FISSION MEASUREMENT ON 5.5 TO 21.7MeV/A 28Si+197Au SYSTEM (Ⅱ) ANGULAR DISTRIBUTION OF ICF AND SF
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According to the distribution of linear momentum transfer (lmt) obtained from the correlation measurement of fission partner,the events of Incomplete Fusion Fission (ICF) and Sequential Fission (SF) were distinguished.The fission angular distributions of both ICF and SF were obtained,respectively.
With calculating the moment of inertia by Cassinian Ovaloid as the fission shape, the angular distributions were fitted by current procedure.The spins of fission nuclei corresponding to ICF and SF are extracted.The relation between spins and bombarding energy is discussed.Besides,the angular distribution in coincidence with complex particles is discussed. 相似文献
With calculating the moment of inertia by Cassinian Ovaloid as the fission shape, the angular distributions were fitted by current procedure.The spins of fission nuclei corresponding to ICF and SF are extracted.The relation between spins and bombarding energy is discussed.Besides,the angular distribution in coincidence with complex particles is discussed. 相似文献
66.
LIU Guo-Xing CHEN Ke-Liang ZHENG Ji-Wen WANG Su-Fang BAI Xing-Ping YU Xian FAN Zhi-Guo 《中国物理C(英文版)》1989,13(8):733-739
The angular distributions of fission fragments for a series of compound nuclei formed in the bombardment of 181Ta,197Au Pb and 209Bi by 12C ions and in the bombardment of natural lead by 14N ions were measu ed with mica track detectors and gold surface barrier detectors.It is shown that all experimental data for the fission fragment angular distributions can be fitted by the statistical scission model of fission fragment angular distribution. 相似文献
67.
The fission cross sections and the evaporation residue cross sections for 12C+209Bi and 14N+Pb reactions were measured with the gold surface barrier silicon detectors and the mica nuclear track detectors.The critical angular momentum ler was deduced from the measured evaporation residue cross section σer on the basis of the sharp-off model.The fission barrier with the particular angular momentum i derived from the condition Γf/Γn=1 at l=le The angular momentum effect of the fission barrier was studied experimentally. 相似文献
68.
在模拟生理条件下(pH 7.4),采用荧光光谱及傅里叶变换红外光谱研究了1-脱氧野尻霉素(1 -DNJ)与人血清白蛋白(HSA)之间的相互作用方式及机理.结果表明,1-DNJ对HSA的荧光猝灭作用主要为静态猝灭,两者之间形成了1∶1的复合物.通过计算获得了不同温度下的结合常数及结合位点数,并根据1-DNJ与HSA结合的热力学参数,确定了两者之间的主要作用力为疏水作用与静电引力.同步荧光光谱显示1-DNJ对HSA的构象产生了影响,并通过傅里叶变换红外光谱确定了HSA二级结构的变化. 相似文献
69.
Li DR Zhang DH Sun CY Zhang JW Yang L Chen J Liu B Su C Zhou WS Lin GQ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(4):1185-1204
An efficient and highly convergent total synthesis of the potent antitumor agent phorboxazole B has been achieved. The synthetic strategy of this synthesis features: 1) a highly efficient substrate-controlled hydrogenation to construct the functionalized cis-tetrahydropyrane unit; 2) iterative crotyl addition to synthesize the segment that contains alternating hydroxyl and methyl substituents; 3) Hg(OAc)2/I2-induced cyclization to establish the cis-tetrahydropyrane moiety; 4) 1,3-asymmetric induction in the Mukaiyama aldol reaction to afford the stereogenic centers at C9 and C3; and 5) the exploration of the Still-Gennari olefination reaction to complete the macrolide ring of phorboxazoloe B. 相似文献
70.