998 resultados para Re-absorption


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稀土钒酸盐是很好的发光和激光材料。本文探讨了助熔剂法生长YVO_4:RE~(3+)(RE~(3+)=Pr~(3+),Sm~(3+),Tb~(3+))晶体的工艺条件。讨论了V_2O_5与Pb_2P_2O_7为助熔剂和温度对晶体成核,生长习性和缺陷的影响。并测定了晶体的结构参数。分别以V_2O_5和Pb_2P_2O_7为助熔剂进行YVO_4:RE~(3+)晶体的生长,结果表明用V_2O_5为助熔剂比用Pb_2P_2O_7为助熔剂要优越得多。以

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LaF_3作为离子选择性电极和对气体的敏感性质已进行了一定的研究,但其他稀土氟化物的敏感性质却未见报道。本文合成了RE_(1-x)B_xF_(3-y),研究了它们的结构、电学性质及敏感性质,得到有可能在150℃使用的固体电解质氧敏材料。 (一) RE_(1-x)B_xF_(3-y)的结构分析 结构分析表明,Ca、Ba置换RE的含量少时,如La_(0.95)Ba_(0.05)F_(3-y)、Ce_(0.95)Ca_(0.05)F_(3-y)的X射线衍射分析结果与LaF_3、CeF_3相似,说明它们是固溶体。而Ca置换RE含量较多时,如Y_(0.71)Ca_(0.29)F_(3-y)、Gd_(0.85)Ca_(0.15)F_(3-主)的X射线衍射分析结果却与相应的YF_3和GdF_3完全不

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将加热活化的AlCl_3与三氯化稀土在苯溶液中反应,合成了2个新的轻稀土中性芳烃配合物RE(C_6H_6)(AlCl_4)_3C_6H_6(RE=La或Nd)。并用元素分析和红外光谱对其进行了表征。测定了含Nd配合物的晶体结构。对2个配合物结构的比较表明,中心金属离子对配合物的结构无明显影响,其键参数的差别主要来自“镧系收缩”。

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本文采用真空下气体输运技术制备RE_(0.06)La_(0.94)Nb_2O_6Cl(RE=Pr、Eu、Tb、Dy)小单晶和多晶粉末样品。测定其晶体结构与LaNb_2O_6Cl的晶体结构相同,为正交晶系;Eu_(0.06)La_(0.94)Nb_2O_6Cl小单晶的晶胞参数为:a=9.751,b=7.321,c=8.364。观察RE_(0.06)La_(0.94)Nb_2O_6Cl(RE=Pr、Eu、Tb、Dy)的特征激发光谱和发射光谱及其能量传递现象。

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R-phycoerythrin (R-PE) was purified from leafy gametophyte of Porphyra haitanensis T. J. Chang et B. F. Zheng (Bangiales, Rhodophyta) by a simple, scaleable procedure. Initially, phycobiliproteins were extracted by repeated freeze-thaw cycles, resulting in release from the algal cells by osmotic shock. Next, R-PE was recovered by applying the crude extract with a high concentration of (NH4)(2)SO4 salt directly to the expanded-bed columns loaded with phenyl-sepharose. An expanded-bed volume twice the settled-bed volume was maintained; then low (NH4)(2)SO4 concentration was used to develop the column. After two rounds of hydrophobic interaction chromatography (HIC), R-PE was purified by anion-exchange column. The method was also successful with free-living conchocelis of P. haitanensis. The purified R-PE was identified with electrophoresis, and absorption and fluorescence emission spectroscopy. The results were in agreement with those previously reported. The yield with a spectroscopic purity (OD565/OD280) higher than 3.2 (the ratio of A(565)/A(620) <= 0.02) was 1.4 mg . g(-1) of leafy gametophyte of P. haitanensis. For the free-living conchocelis of P. haitanensis extract, R-PE could be purified successfully with only one round of HIC. The yield with a spectroscopic purity (OD565/OD280) higher than 3.2 (the ratio of A(565)/A(620) <= 0.02) was 5.0 mg . g(-1) of free-living conchocelis of P. haitanensis. The method described here is a scaleable technology that allows a large quantity of R-PE to be recovered from the unclarified P. haitanensis crude extract. It is also a high protein recovery technology, reducing both processing costs and times, which enhances the value of this endemic Porphyra of China.

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Physiological data from extreme habitat organisms during stresses are vital information for comprehending their survival. The intertidal seaweeds are exposed to a combination of environmental stresses, the most influential one being regular dehydration and re-hydration. Porphyra katadai var. hemiphylla is a unique intertidal macroalga species with two longitudinally separated, color distinct, sexually different parts. In this study, the photosynthetic performance of both PSI and PSII of the two sexually different parts of P. katadai thalli during dehydration and re-hydration was investigated. Under low-grade dehydration the variation of photosystems of male and female parts of P. katadai were similar. However, after the absolute water content reached 42%, the PSI of the female parts was nearly shut down while that of the male parts still coordinated well and worked properly with PSII. Furthermore, after re-hydration with a better conditioned PSI, the dehydrated male parts were able to restore photosynthesis within 1 h, while the female parts did not. It is concluded that in P. katadai the susceptibility of photosynthesis to dehydration depends on the accommodative ability of PSI. The relatively lower content of phycobiliprotein in male parts may be the cause for a stronger PSI after severe dehydration.

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以奥利亚罗非鱼(Oreochromis aureus)为实验对象,设计了3种不同的摄食类型,分别是鲜活饵料组、饥饿3周后饱食投喂组和人工饲料组。鲜活饵料组投喂冰冻赤子爱胜蚓,利用蚯蚓体内丰富的营养成分和活性物质,以期获得奥利亚罗非鱼良好的生长状况;饥饿后饱食组是指饥饿3周后,以人工饲料饱食投喂2周,用于研究饥饿与补偿生长获得快速生长时血液理化指标的变化情况;人工饲料组作为对照组。纯淡水条件下养殖,水温25±2℃。测定了奥利亚罗非鱼在3种摄食类型饲喂下某些血液生理生化指标变化的情况,并将指标变化情况与增重率做相关性分析,试图找出能够反映奥利亚罗非鱼生长性能的血液生理生化指标。 研究结果表明,奥利亚罗非鱼在饥饿3周后获得了补偿生长,补偿生长时的增重率和特定生长率显著高于人工饲料组(P<0.05),高于鲜活饵料组,但差别不显著;相关性分析研究表明血清总蛋白、胆固醇、四碘甲状腺原氨酸(T4)与增重率极显著相关(P<0.01),血红蛋白显著相关(P<0.05),红细胞、白细胞、碱性磷酸酶高度相关(相关系数为0.580、0.551和0.557),因此,建议血清总蛋白、胆固醇和血红蛋白可作为能够反映罗非鱼生长性能的新指标。 根据序列设计引物,PCR反应条件:变性温度:95 ℃,3 min;退火温度:57℃,20 sec;延伸温度:72℃,5 min,共36个循环,从牙鲆、黑鲪和鲈鱼中克隆出胰岛素样生长因子(IGF-Ⅰ)部分序列,首次证实了IGF-Ⅰ在3种海水鱼中的存在。 利用蛋氨酸与ZnSO4•7H2O,在pH 5.5、80℃下,反应1小时,采用蛋氨酸与硫酸锌2:1的配料比,合成出了产物蛋氨酸螯合锌,蛋氨酸螯合锌外观白色,粉状,室温下微溶于水,不溶于乙醇,并用原子吸收光谱法测定其含锌量为15%,螯合率为88.2%。

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Highly pathogenic avian influenza H5N1 virus has swept west across the globe and caused serious debates on the roles of migratory birds in virus circulation since the first large-scale outbreak in migratory birds of Lake Qinghai, 2005. In May 2006, another outbreak struck Lake Qinghai and six novel strains were isolated. To elucidate these QH06 viruses, the six isolates were subjected to whole-genome sequencing. Phylogenetic analyses show that QH06 viruses are derived from the lineages of Lake Qinghai, 2005. Five of the six novel isolates are adjacent to the strain A/Cygnus olor/Croatia/1/05, and the last one is related to the strain A/duck/Novosibirsk/ 02/05, an isolate of the flyway. Antigenic analyses suggest that QH06 and QH05 viruses are similar to each other. These findings implicate that QH06 viruses of Lake Qinghai may travel back via migratory birds, though not ruling out the possibility of local circulation of viruses of Lake Qinghai.

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四川力马河镍矿是峨眉山大火成岩省一个重要的岩浆硫化物矿床。本文通过对其主要岩、矿石类型Re、0s及其同位素组成的分析,综合探讨了成矿岩体原始岩浆性质、矿石硫化物成因、成矿机制及Re-Os同位素等时线年龄。结果表明,力马河镍不同类型岩矿石样品初始0s同位素组成是不均一的,富硫化物的网脉状矿石 及其选纯硫化物Os同位素组成初始值差异较小,其等时线年龄为265士35 Ma,与岩体错石SHRIMP年龄263士3Ma基本相当}硫化物含量较低的岩、矿石样品间初始Os同位素组成差异较大,其表观等时线年龄大于成矿年龄。分析认为。岩矿样品初始Os同位素组成的不均一是由含较高放射成因187Os丰度的硫化物熔体和含较低放射成因187Os丰度的硅酸盐熔体不同比例混合造成的。混合模型分析表明,硫化物含量超过3O% 的矿石样品初始187 Os/188Os基本接近,硫化物含量低于3O %的岩矿石样品初始 187Os/188Os随硫化物含量上的不同,差异很大,为岩浆硫化物矿床Re-Os等时线年龄出现多组年龄解的现象提供了一种可能的解释。成矿岩体中含放射成因187Os丰度最低的岩石样品 (t一260Ma)在5左右、Cu/Pd比值在7000左右,表明是基本没有受到地壳混染及硫化物熔离影响的原始岩浆结晶分异产物,估计原始岩浆Os含量在1×10 左右,为苦橄质岩浆。矿石硫化物Re/Os比值显著高于任何赋矿橄榄岩,7o,(£一260Ma)高达110左右,综合分析揭示了力马河镍矿硫化物为二次熔离成因,模式分析认为,矿石硫化物是由原始岩浆经历R一2000左右的硫化物熔离后,其亏损岩浆再经R一200左右的硫化物熔离形成,与二次熔离相对应,成矿岩浆也经历了两次混染作用,分别为上、下地壳7%左右的混染。

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跃北红岭钨矿为产在热水复式岩体之中的中型钨多金属矿床, 矿化类型为石英脉型黑钨矿化和蚀变花岗岩型白钨矿化。对矿区含矿石英脉中8个辉钼矿样品进行Re-Os同位素测定, 获得等时线年龄及模式年龄的加权平均值分别为159.1±1.5Ma和158.8±0.88Ma. 等时线纵截距为-0.010±0.041, 说明样品中不存在可测定的初始187Os. 统计表明南岭地区中东段钨锡矿床的成矿年龄多集中在150~160Ma。粤北已有的几个钨矿成矿年龄与区域燕山期花岗岩大规模侵位时期一致,表明南岭地区花岗岩成岩成矿可能不存在明显的时差。