105 resultados para AMS(14)C dating
Resumo:
Our rock magnetic analysis of core Ph05 from the West Philippine Sea demonstrates that the core preserves a strong, stable remanent magnetization and meets the magnetic mineral criteria for relative paleointensity (RPI) analyses. The magnetic minerals in the sequence are dominated by pseudosingle-domain magnetite, and the concentration of magnetic minerals is at the same scale. Both the conventional normalizing method and the pseudo-Thellier method were used in conjunction with the examination of the rock magnetic properties and natural remanent magnetization. Susceptibility (chi), anhysteretic remnant magnetization (ARM) and saturation isothermal remnant magnetization (SIRM) were used as the natural remanent magnetization normalizer. However, coherence analysis indicated that only ARM is more suitable for paleointensity reconstruction. The age model of core is established based on oxygen isotope data and AMS(14)C data, which is consistent with the age model estimated from RPI records. The relative paleointensity data provide a continuous record of the intensity variation during the last 200 ka, which correlates well with the global references RPI stacks. Several prominent low paleointensity values are identified and are correlated to the main RPI minima in the SINT-200 record, suggesting that the sediments have recorded the real changes of geomagnetic field.
Resumo:
AXIS(14)C dating and grain-size analysis for Core DD2, located at the north of the Yangtze River-derived mud off the Zhejiang-Fujian coasts in the inner shelf of the East China Sea, provide us a high-resolution grain-size distribution curve varying with depth and time. Data in the upper mud layer of Core DD2 indicate that there are at least 9 abrupt grain-size increasing in recent 2000 years, with each corresponding very well with the low-temperature events in Chinese history, which might result from the periodical strengthening of the East Asian Winter Monsoon (EAWM), including the first-revealed maximum temperature lowering event at around 990 a BP. At the same time, the finer grain size section in Core DD2 agrees well with the Sui-Tang Warming Period (600-1000 a AD) defined previously by Zhu Kezhen, during which the climate had a warm, cold and warm fluctuation, with a dominated cooling period of 750-850 a AD. The Little Ice Age (LIA) can also be identified in the core. It starts around 1450 a AD and was followed by a subsequent cooling events at 1510, 1670 and 1840 a AD. Timing of these cold events revealed here still needs to be further verified owing to some current uncertainty of dating we used in this study.
Resumo:
Samples of two cores, Cores M5-5 and M7-4 in the Bohai Sea were analyzed in isotopes, grain size, heavy minerals, chemical compositions, and 14 C dating to reconstruct the sedimentation during the Holocene. Abrupt change in carbon and oxygen stable isotopes was recognized at Core M5-5 at about 6400 a BP, which was likely due to the intrusion of the Yellow Sea Warm Current (YSWC) extension into the Bohai Sea. At Core M7-4, sediments between 5900 and 6600 a BP (150-260 cm depth) became coarse-grained, containing rich garnet, high manganese content, and nil autogenic pyrite, indicating a very dynamic sedimentary event during which the ambience was transformed from reductive to oxidative, and sedimentation boosted. Meanwhile, the YSWC had invaded into the Bohai Sea indicated by rich planktonic foraminifera in this event. (c) 2008 Elsevier Ltd. All rights reserved.
Resumo:
Two deep sea cores (Ph05-5, 16.05 degrees N, 124.34 degrees E, water depth 3382m and WP3: 22.15 degrees N, 122.95 degrees E, water depth 2700m) retrieved from the Kuroshio source region of the western Philippine Sea were selected to carry out the CaCO3 and calcareous nannofossil faunas study. Based on AMS(14)C data and comparing tire oxygen isotope curve with SPECMAP delta O-18 (Martinson et al., 1987) a stratigraphy was established. And, combining the changes of primary productivity and dissolution index of carbonate, the carbonate cycle and its control factors were analyzed in this region during the last 190ka BP. The carbonate contents showed higher values in the glacial periods and lower values during the interglacial and Holocene periods, which characteristics was similar to the tendency of "Pacific Type" carbonate cycle. However, there were high carbonate contents in the warm period and low values during the cold interval, which displayed the same tendency with the "Atlantic Type" carbonate cycle during the last glacial period (MIS4-2) in the east of Phillipines. The variations of primary productivity and carbonate dissolution index indicated that the carbonate dissolution was a major factor controlling the carbonate content in tire cast of Philippines, and the variations in carbonate contents were mainly affected by the productivity of calcareous organism in the Southeast of Taiwan. The "Atlantic Type" carbonate cycle in the cast of Phillipines during the last glacial period (MIS4-2) was an effect of the process of dissolution combined with the change of primary productivity.
Resumo:
本文采用取自冲绳海槽的91个站位的表层样品和2个柱状岩芯,通过微体古生物有孔虫分析、氧碳同位素测试、AMS~(14)C测年、沉积物粒度和地球化学分析,探讨了现代生物群落、表层沉积物氧同位素与现代海洋环境之间的关系,进而对冲绳海槽区域近4万年来的古海洋环境和古黑潮演化进行了详细的研究。表层沉积物中的浮游有孔虫氧同位素与现代海洋环境之间的关系密切,浮游有孔虫从G.ruber到G.sacculifer到N.dutertrei其δ~(18)O值由轻变重,表明三种有孔虫其生活水层依次由浅到深。在横穿海槽的剖面上浮游有孔虫δ~(18)O在近陆端因受冲淡小影响较强而变轻,而在东侧站位,受黑潮暖流或其支流的影响氧同位素同样有变轻的趋势。N. dutertrei和G.ruber的氧同位素差值表明了冲绳海槽北部区域黑潮支流对表层水体的影响要大于次表层水体,而在冲绳海槽南部区域,黑潮暖流对次表层水体有相对较强的影响。冲绳海槽南部表层沉积物中的浮游有孔虫整体上属于赤道区组合,溶解作用对该区的浮游有孔虫群落有显的影响,冲绳海槽北部区浮游有孔虫组合对具有温带群落的特征。浮游有孔虫分布与海洋环境密切相关,南北区的浮游有孔虫分布都明显受暖流的影响,在暖流的主流轴处浮游有孔虫丰度通常较高。冲绳海槽具有相对较浅的碳酸盐溶跃面,浮游有孔虫丰度和底栖有孔虫深水胶结壳的含量都进一步表明了该区碳酸钙溶跃面大约在1700 m水深左右,比开放大洋明显要浅得多。表层沉积物中的底栖有孔虫主要受水深和水团等因素的制约。水深制约着有孔虫属种的分带,也影响底栖有孔虫的组合。根据Q型因子分析,冲绳海槽南部表层沉积物中的底栖有孔虫从陆架连缘到海槽底部可以划分为5个特定的组合,分别对应黑潮表层水和次层水影响环境、黑潮中层水影响环境、溶跃面以上的黑潮深层水影响环境、黑潮底层水团影响环境和溶解作用较强的槽底环境;北部区的底栖有孔虫群落反映了四个组合,分别代表了陆架混合水团影响环境、黑潮暖流中层水影响环境、冷涡沉积和上升流区影响环境以及对马暖流水团影响下的环境。以氧同位素曲线为基础,结合AMS~(14)C测年和生物地层学对柱状岩芯进行了地层划分和对比,E107孔记录了冰消期以来大约15,000 a来的古环境演化记录,具有较高的沉积速率,DOC-42孔保存在主要是末冰期中40-10ka BP期间的古环境沉积记录,沉积物记录的分辨率相对较低。浮游有孔虫有碎壳比和底栖有孔虫深海胶结壳含量表明了现代冲绳海槽的浅溶跃面是大约最近2000 a BP才开始突然变浅形成的,碳酸盐的溶解作用从冰消期到现在逐增强。冲绳海槽南部E107孔的底栖有孔虫组合把映了15,000 a来的底层水团具有两种完全不同的营养状况,约6500 a BP以前有机质通量较高,6500 a BP以后有机质通量则明显降低。DOC-42孔的底栖有孔虫组合反映该区约4万年以来的底部水团演化主要受有机质通量和氧含量的共同制约,氧同位素3期主要为高有机质通量的沉积环境,伴随有氧含量水平的较大波动;氧同位素2期有机质通量有所降低,氧含量整体为中等水平;氧同位素1期早期义部水体则较高氧含量为主。浮游有孔虫温跃层转换函数反映了冲绳海槽中部的温跃层在约13100 a BP有一个明显的变化,在这之前产温跃层深度较浅,平均89 m,而在该时间以后,温跃层平均深度变为166 m。此外在160 cm处和100 cm的温跃层深度的两次明显的降低,分别对应于新仙女木事件和黑潮暖流的重新入侵,表明这两个事件导致了海洋上层水体结构的突然变化。冲绳海槽北部浮游有孔虫转换函数古温度和浮游有孔虫的低温、低盐特征种反映了在氧同位素3期早期约40000a BP和氧同位素2期间存在两个明显的低温、低盐阶段,可能与沿岸水在该期间加强有关。其中氧同位素3期早期的表层海水古水温比末次冰期还要低,反映了区域海洋环境的重大变化。冲绳海槽南部E107孔的沉积物粒度、地球化学特征、黑潮特征指示种、表层古水温以及底层水团的性质在6500 a BP左右发生了重大的改变,与冲绳海槽南部的其他岩芯反映的古环境化基本一致,表明了南部海槽在6500 a BP前后古黑潮流径发生了重大变化。而冲绳海槽北部区域2万年以来的古环境则与南部有明显差异,总结前人对冲绳海槽古黑潮流径的研究,笔者对未次冰盛期古黑潮流径提出了新的推测。
Resumo:
The main research projects reported in this paper are the establishment of a luminescence (OSL/TL) dating laboratory in The Institute of Geology and Geophysics, CAS, and studies on OSL dating technique and protocol of sediments from North China. These projects have been suggested in order to fit in with the needs of research developments in environmental changes, in particular the aridity and desertification in North China. A new luminescence dating laboratory in which there are a Rise TL/OSL-DA-15B/C reader with Sr-90 beta source, a set of Little More Tape 9022 alpha and beta irradiators, three set of Daybreak 583 intelligent alpha counters and sample preparation system has been set up in the Institute in June 2001. The courses of the establishment of a new laboratory involved a series of technical works, besides making a suitable choice of the equipment, as follows: installing and testing TL/OSL reader, calibrating the dose rate of the beta and alpha sources in the irradiators with the standard sources, testing and calibrating the count rates of the thick source alpha counting in the alpha counters with a standard sample, and then dating of the know age samples to check and examine the OSL/TL dating system. All data obtained from above calibrations and tests show that the established OSL/TL system, including the used equipment in it, can be used to determine age of the geological and archaeological samples with an error of equivalent dose (De) of less than 5%. The OSL dates of several sediment samples obtained from the system are good agreement with those from the OSL dating laboratory in Hong Kong University and ~(14)C dates within 1 - 2 standard deviations. The studies on OSL dating technique and protocol of sediment samples being in progress involve the De determinations with single aliquot regeneration (SAR) (Murray and Wintle, 2000) of the coarse grain quartz from sand dune samples and comparison of the De determinations obtained from SAR with those measured by using multiple aliquot regeneration of loess fine grains. The preliminary results from these research works are shown as follows. The very low natural equivalent dose (De) of about 0.012 - 0.03 Gy, corresponding age of less than 10 years, for BLSL (blue light stimulated luminescence) of the coarse grain quartz from modern sand dune samples in Horqin sand fields has been determined with both the SAR and multiple aliquot regeneration (MAR) techniques. This imply that the BLSL signal zeroing of the quartz could be reached before burying of the sand in Horqin sand fields. The De values and ages of the coarse grain quartz measured with SAR protocol are in good agreement with those obtained from multiple aliquot technique for the modern sand dune samples, but the errors of De from the MAR is greater than those from the SAR. This may imply that the higher precision of age determination for younger sand dune samples could be achieved with the SAR of coarse grain quartz. The MAR combining with "Australian Slide method" may be a perfect choice for De measurements of loess fine grain samples on the basis of analysis of De values obtained from the SAR and from the MAR. The former can be employed to obtain a reliable age estimate of loess sample as older as approximately SO ka BR There is a great difference between De determinations from the (post-IR) OSL of the SAR (Roberts and Wintle, 2001) and those from independent or expected estimates for the older samples. However, the age estimates obtained from the (post-IR) OSL of the SAR are mostly closed to the independent age determinations for the younger (age less than 10 ka) fine grain samples. It may be suggested that the (post-IR) OSL of the SAR protocol of the fine grain fraction would be a suitable choice to dating of the younger samples, but may be unsuitable for the older samples.
Resumo:
本文以桃(Prunus persica L. cv. Bayuecui.)栽培种‘八月脆’和芒果(Mangifera indica L.)栽培种‘圣心’为材料,研究外源草酸对采后果实的生理生化效应及其作用机理,为果实贮藏保鲜提供新方法。采后桃果实用1、5 mM的草酸溶液浸果10 min,以浸水10 min为对照,然后在常温下贮藏,测定果实在贮藏期间对草酸处理的一些生理生化反应。芒果经采后杀菌剂(post- P)、采后草酸(post-OA)、采前+采后草酸(pre-OA + post-OA)、采前Ca + 采后草酸处理(pre-Ca + post-OA)处理,以采后浸水为对照,然后分别将果实在常温(25 C)、低温(14 C)和控制性气调(3% CO2 + 2% O2 ,14 ± 1 C)下贮藏,测定草酸处理对芒果的成熟进程、病情发展及其相关生理指标的影响。研究结果表明如下: 1.与对照相比,草酸处理的桃果实在贮藏期间果实的电解质渗漏量和呼吸速率降低、果实硬度高、果实的抗氧化酶(超氧化物岐化酶、SOD;过氧化物酶,POD;过氧化氢酶、CAT;抗坏血酸过氧化物酶、APX)和多酚氧化酶(PPO)活性提高、脂氧合酶(LOX)活性降低。同时,在贮藏后期,果实的活性氧自由基(ROS)产量(超氧阴离子、O2.;过氧化氢、H2O2)和丙二醛(MDA)含量降低。草酸的这些生理效应有利于保持膜的完整性和延缓桃果实的成熟;草酸诱导POD、SOD、PPO活性可能有助于提高采后果实的抗病性。 2.外源5、10 mM浓度的草酸(pH值中和或不中和)对芒果炭疽病原菌(Colletotrichum gloeosporioides)孢子萌发和菌丝生长均表现出显著的抑制作用。这种作用不仅与草酸降低培养基(PDA)的pH值相关,而且与草酸独特的化学特性相关。 3.在常温、低温和控制性气调贮藏下,采后草酸、采前 + 采后草酸、采前Ca + 采后草酸处理均能有效减缓芒果果实的软化速率,延缓芒果的成熟进程,降低芒果的病情指数,同时改善芒果成熟时的表皮着色,对果实完全后熟时的可溶性固形物(SSC)、可滴定酸(TA)含量、果肉口感均没有产生负面的影响。 4.草酸处理增强芒果细胞膜的稳定性,诱导提高芒果抗氧化酶活性,特别是提高果皮SOD、APX活性,降低LOX活性,以及降低果皮O2.、H2O2 和果肉H2O2含量,抑制采后果实的乙烯生物合成。这些生理生化效应与延缓芒果的成熟衰老和提高果实的抗病性相关。 5. 采后草酸、采前 + 采后草酸和采前Ca + 采后草酸处理表现出高效低廉、无毒无副作用、易操作等优点,是芒果采后贮藏保鲜的可供选、具有实际应用前景的新方法。
Resumo:
本实验对三种萝藦科植物通光散(Marsdenia tenacissima)、黑水藤(Biondia insignis Tsiang)和徐长卿(Cynanchum Paniculatum)中的C21甾体化合物进行了研究。从通光散藤茎乙酸乙酯提取物的水解产物中,分离得到两类八个C21甾类甙元。经光谱鉴定,它们的结构分别为11α-O-(2-甲基)-丁酰基-12β-O-顺芷酰通光藤甙元乙(1),11α-O-乙酰基-12β-O-乙酰基通光藤甙元乙(2),11α-O-(2-甲基)-丁酰基-12β-O-乙酰基通光藤甙元乙(3), 11α-O-苯甲酰基-12β-O-乙酰基通光藤甙元乙(4), 11α-O-顺芷酰基-12β-O-乙酰基通光藤甙元乙(5)11α-O-顺芷酰基-12β-O-顺芷酰基通光藤甙元乙(6),12β-O-乙酰基通光藤甙元甲(7)和12β-O-顺芷酰基通光藤甙元甲(8)。其中,化合物2和8为新化合物。从黑水藤乙醇提取物的水解产物中,分离得到了两个C21甾体化合物。经1D、2D NMR技术鉴定,分别为(3β,14β,15β,17β)-3, 14-二羟基-15,16-裂-孕甾-5-烯-15-醛-16-半缩醛-20-酮(1)和白前甙元C(2)。其中1为15,16-裂环的新骨架类型的C21甾体化合物,命名为黑水藤甙元甲。从采购于昆明、浙江、湖南三地药材市场的徐长卿的根及根茎中,分离得到了18个化合物(其中昆明徐长卿6个,浙江徐长卿9个,湖南徐长卿3个)。经光谱数据分析,这些化合物被鉴定为:cynapanoside-C (1), cynapanoside-A (2), 白前甙元B 3-O-β-D-磁嘛吡喃糖甙(3),白前甙元C 3-O-β-D-葡萄吡喃糖基-(1 → 4)-α-L-2-脱氧洋地黄吡喃糖基-(1 → 4)-β-D-洋地黄吡喃糖基-(1 → 4)-β-D-夹竹吡喃糖甙(4),白前甙元C3-O-β-D-葡萄吡喃糖基-(1 → 4)-α-D-夹竹桃吡喃糖基-(1 → 4)-β-D-洋地黄吡喃糖基-(1 → 4)-β-D-夹竹桃吡喃糖甙(5),白前甙元C 3-O-β-D-葡萄吡喃糖基-(1 → 4)-β-D-葡萄吡喃糖基-(1 → 4)-α-D-夹竹桃吡喃糖基-(1 → 4)-β-D-洋地黄吡喃糖基-(1 → 4)-β-D-夹竹桃吡喃糖甙(6),cynatratoside-B (7),cynatratoside-C (8);glaucoside A(9),新白薇甙元B 3-O-β-L-磁嘛吡喃糖基-(1 → 4)-β-D-洋黄吡喃糖基-(1 → 4)-β-D-夹竹桃吡喃糖甙(10),白前甙元 A 3-O-α-L-磁嘛吡喃糖基-(1 → 4)-β-D-洋地黄吡喃糖基-(1 → 4)-β-D-磁嘛吡喃糖甙(11),白前甙元 B 3-O-α-L-磁糖基吡喃糖基-(1 → 4)-β-D-磁嘛吡喃糖基-(1 → 4)-β-D-磁嘛吡喃糖甙(12),白前甙元D 3-O-α-L-磁嘛吡喃糖基(1 → 4)-β-D-洋地黄吡喃糖基-(1 → 4)-β-D-磁嘛吡喃糖甙(13),白前甙元 C 3-O-β-D-葡萄吡喃糖基-(1 → 4)-β-D-葡萄吡喃糖基-(1 → 4)-α-L-2-脱氧洋地黄吡喃糖基-(1 → 4)-β-D-磁嘛吡喃糖基-(1 → 4)-β-D-夹竹桃吡喃糖甙(14),白前甙元 C 3-O-β-D-葡萄吡喃糖基-(1 → 4)-β-D-葡萄吡喃糖基-(1 → 4)-α-L-磁嘛吡喃糖基-(1 → 4)-β-D-洋地黄吡喃糖基-(1 → 4)-β-D-夹竹桃吡喃糖甙(15),白前甙元 B 3-O-α-D-夹竹桃吡喃糖基-(1 → 4)-β-D-洋地黄吡喃糖基-(1 → 4)-β-D-磁嘛吡喃糖甙(16),白前甙元 D 3-O-α-D-夹竹桃吡喃糖基-(1 → 4)-β-D-洋地黄吡喃糖基-(1 → 4)-β-D-磁嘛吡喃糖甙(17),白前甙元月B 3-O-α-L-磁嘛吡喃糖基-(1 → 4)-β-D-洋地黄吡喃糖基-(1 → 4)-β-D-磁嘛吡喃糖甙(18)。其中,化合物3-6,10-18为新化合物,10的甙元为一个新甙元,命名为新白薇甙无B。
Resumo:
用G带,C带和银染技术对青鼬的核型观察分析结果:2n=40,双臂染色体16对,单臂染色体3对。X染色体为中着丝粒染色体。No.14同源染色体着丝点C带,一条呈阳性,另一条呈阴性。其余全部着丝点C带均显示强阳性。No.8染色体长臂显示C带阳性,No.11和No.13染色体的短臂具端位异染色质。仅有1对Ag-NORs,分布于No.15染色体的次缢痕部位,其短臂显示C带阳性,No.19染色体整个呈C带阳性。并同貂属其他种作了比较,初步探讨了青鼬的分类地位和亲缘关系。图版1表1参17
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用~(14)C标记直链烷基苯磺酸盐,(~(14)C-LAS),研究了在由塘泥、水草、鱼、螺蛳和溞构成的室内模拟水生态系统中,LAS的降解规律、在水生生物体内的积累分布及其与在水中降解之间的相互关系.
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随着基质辅助激光解吸/离(MALDI)和电喷雾电离(ESI)技术的发展,“软电离”质谱在一些新领域正在发挥着越来越大的作用。本论文运用这些新技术对二萜类生物碱、环糊精与氨基酸复合物和环糊精与肽复合物进行了系统地研究。具体研究结果如下:一、附子中二萜类生物碱的质谱研究使用基质辅助激光解吸飞行时间质谱仪(MALDI-TOF/MS)研究了附子提取物中C-19二萜类生物碱。实验结果表明:MALDI适合同时检测粗提物中多种生物碱,并且在分析速度和灵敏度方面明显优于其它方法。在附子甲醇提取物中检测到三类14种已知生物碱(单双酯型生物碱、阿替生型生物碱和脂类生物碱)和三种未知生物碱。同时还进行了生物碱萃取方法优化实验研究,并探讨了复方煎煮过程中成分-成分之间的相互作用。研究发现:生物碱的极性、碱性和毒性与生物碱C-8取代基相关,而且该基团在电离过程中容易形成中性碎片;在煎煮过程中甘草促进附子中剧毒的双酯型生物碱水解为低毒性的单酯型生物碱,从而证实了复方解毒机理。把电喷雾质谱(ESI-MS)和多级串联质谱(MS~n,n = 2-10)结合用以分析附子中脂类生物碱的成分。ESI-MS能够依据分子量的不同实现脂类生物碱的有效分离,并且Ms~n可以提供有关分子结构的信息。这样,就在附子乙醚提取物中确认出了12种已知脂类生物碱,并发现四种新的脂类生物碱。二、环糊精/氨基酸和环糊精/肽两种复合物的气相行为在10mM醋酸铵缓冲的环糊精(CD)/氨基酸(AAs)溶液的ESI-MS谱中,分别观察到α、β-CD与9种氨基酸复合物的正负离子;结合碰撞诱导解离(CID)技术确定了气相复合物的价键性质和结构。溶液中CD和AAs之间的疏才斜目互作用由于ESI过程中溶剂化作用的减弱而减弱,甚至完全消失,而分子之间的静电作用和氢键可能因此被加强。去质子化复合物的CID实验显示:当CD复合物从溶液相转入气相时,分子之间的主要作用力发生变化,静电相互作用成为主要作用力。研究还发现:β-CD/芳香氨基酸复合物的稳定性与氨基酸侧链和cD空腔之间的尺寸适合有关。因为CD/芳香氨基酸复合物与CD/其它氨基酸复合物的解离途径是不同的。由于芳香侧链被包结在CD空腔内,当CD/芳香氨 基酸复合物解离时,CD发生“爆裂”。为了进一步解释气相中CD和氨基酸的复合形式,引入氨基酸侧链极性表面积以评价氨基酸侧链对复合物稳定性的贡献。结果显示:氨基酸侧链羟基对复合物稳定性没有明显影响,这更加证明了在气-液两相中CD/芳香氨基酸复合物的结构是一致的。用ESI-MS和MS~n对α、β-CD与谷胱甘肽(GSH)及其修饰物进行研究,实验结果表明:两种环糊精均能催化GSH氧化反应。1:1和1:2CD/GSH复合物的CID揭示了分子之间具有较强的氢键作用。与GSH二聚体相比,1:2复合物作为催化氧化反应的中间体能够提供双分子GSH氧化反应的空间条件。此外,在1:1CD/GSH复合物的CID谱中观察到了GSH的氧化产物,说明在cID的离子富集和活化过程中会发生复合物离子-复合物离子之间的相互作用。这一结果不仅解释了CD催化反应的机理,同时揭示了气相复合物的化学性质。
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Within the Boltzmann-Langevin equation, the neutron cluster production cross sections in the reactions induced by Be-14, He-8, He-6, Li-11, B-17, Be-11, C-19 on C-12 at 35MeV/u were studied. The experimental data for (4)n production cross section from Be-14+C-12 at 35MeV/u can be reproduced. It is found that the production cross section of neutron cluster is large in the reaction that the projectile has more halo nucleons. And the projectiles with big mass number are easy to produce the neutron cluster, when they have the same number of halo nucleons. The neutron cluster is probably mainly from the halo nucleons of projectile.
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A novel organic-inorganic hybrid vanadium oxide [V4O10(o-phen)(2)], involving all vanadium atoms present in +5 oxidation, has been hydrothermally synthesized and characterized by elemental analysis, IR, UV-vis, ESR, XPS spectra and TG-DTA thermal analysis. The single-crystal X-ray diffraction shows that the red-brown crystal is formed in the triclinic system, space group P (1) over bar, a = 9.782(2), b = 6.5124(14), c = 19.765(4) Angstrom, alpha = 89.94(2)degrees, beta = 100.66(2)degrees, gamma = 89.86(2)degrees. The title compound exhibits an infinite one-dimensional ladder-type tetravanadate skeleton with organonitrogen donors of o-phenanthroline ligands coordinated directly to the vanadium oxide framework.
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Electrospray ionization (ESI) combined with multiple-stage tandem mass spectrometry (MSn) was used to directly analyze the glycolipid mixture from bacteria Bacillus pumilus without preliminary separation. Full scan ESI-MS revealed the composition of picomole quantities of glycerolglycolipid species containing C-14-C-19 fatty acids, some of which were monounsaturated, Two main components were identified from their molecular masses and fragmentation pathways. The fragmentation pathway of the known compound compared with the investigated compound verified the proposed structure as 1(3)-acyl-2-pentadecanoyl-3(1)-O-[beta-D-glucopyranosyl-(1-->6)-O-beta-D-glucopyranosyl]-sn-glycerols. A comparison of the multiple tandem mass spectra of the different alkali-metal cation adducts indicates that the intensity of fragments and the dissociation pathways are dependent on the alkali-metal type, The basic structures of glycerolglycolipids were reflected clearly from the fragmentation patterns of the sodium cations, The intense fragments of the sugar residue from the precursor ions were obtained from the lithiated adduct ions. ESI-MSn spectra of [M + K](+) ions did not provide as much fragmentation as [M + Na](+) and [M + Li](+) adducts, but their spectra allow the position of glycerol acylation to be determined. On the basis of MS2 spectra of[M + K](+) ions, it was established that all components have a C-15:0 fatty acid at the sn-2 position of the glycerol backbone and C-14-C-19 acids at the sn-1 position of the glycerol backbone. Copyright (C) 1999 John Wiley & Sons, Ltd.