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南通元代古船的木材鉴定 总被引：1，自引：0，他引：1
本文对南通如东县出土的元代古船作了木材鉴定，古船用材有杉科的杉木，杨柳科的柳树和榆科的榉树等木材．根据古船用材材种分析，为我国南方造的船． 相似文献
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Tiger,Bengal and Domestic Cat Embryos Produced by Homospecific and Interspecific Zona‐Free Nuclear Transfer 
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下载免费PDF全文 LN Moro J Jarazo C Buemo MI Hiriart A Sestelo DF Salamone 《Reproduction in domestic animals》2015,50(5):849-857
The aim of this study was to evaluate three different cloning strategies in the domestic cat (Felis silvestris) and to use the most efficient to generate wild felid embryos by interspecific cloning (iSCNT) using Bengal (a hybrid formed by the cross of Felis silvestris and Prionailurus bengalensis) and tiger (Panthera tigris) donor cells. In experiment 1, zona‐free (ZP‐free) cloning resulted in higher fusion and expanded blastocyst rates with respect to zona included cloning techniques that involved fusion or injection of the donor cell. In experiment 2, ZP‐free iSCNT and embryo aggregation (2X) were assessed. Division velocity and blastocyst rates were increased by embryo aggregation in the three species. Despite fewer tiger embryos than Bengal and cat embryos reached the blastocyst stage, Tiger 2X group increased the percentage of blastocysts with respect to Tiger 1X group (3.2% vs 12.1%, respectively). Moreover, blastocyst cell number was almost duplicated in aggregated embryos with respect to non‐aggregated ones within Bengal and tiger groups (278.3 ± 61.9 vs 516.8 ± 103.6 for Bengal 1X and Bengal 2X groups, respectively; 41 vs 220 ± 60 for Tiger 1X and Tiger 2X groups, respectively). OCT4 analysis also revealed that tiger blastocysts had higher proportion of OCT4‐positive cells with respect to Bengal blastocysts and cat intracytoplasmic sperm injection blastocysts. In conclusion, ZP‐free cloning has improved the quality of cat embryos with respect to the other cloning techniques evaluated and was successfully applied in iSCNT complemented with embryo aggregation. 相似文献
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为比较卤虫无节幼体(Arternia nauplii)和配合饵料的饲喂效果,分别采用两种饵料饲养30日龄的诸氏鲻虾虎鱼(Mugilogobius chulae)75d,比较存活、生长和全鱼成分。结果表明,卤虫组的存活率较高(≥52%),显著高于配合饵料组(14%～21%);配合饲料组的相对增重率(GW)为2 916.8%～3 998.7%,特定生长率(SGR)为4.5～5.0,生长效果优于卤虫组(GW为1 826.5%～2 101.7%,SGR为3.9～4.1);全鱼成分测定,卤虫组的水分、粗蛋白、粗脂肪、灰分含量分别为72.7%、19.5%、4.7%、3.0%,配合饵料组的分别为70.5%、18.7%、5.8%、3.5%,两组没有显著差异。适当延长饲喂卤虫无节幼体的时间,然后采用配合饵料进行饲养,能提高存活率并获得较好的生长效果。 相似文献
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Neuronal necrosis in budgerigars treated with dimetridazole 总被引：1，自引：0，他引：1
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The ICSI procedure is potentially of great value for felids, and it has not been extensively studied in these species. The objectives of this work were to determine the best conditions for ICSI in the domestic cat (DC) to generate interspecific embryos by injecting cheetah (Ch) and leopard (Leo) spermatozoa. Firstly, DC oocytes were matured with insulin–transferrin–selenium (ITS) or without it (MM) and cultured using atmospheric (21%) or low (5%) oxygen tension after ICSI. The group ITS‐5%O2 showed the highest blastocyst rate (p < 0.05), 20.9% vs 8.7%, 7% and 6.5%, for MM‐21%O2, MM‐5%O2 and ITS‐21%O2, respectively. The best conditions were used to generate the interspecific embryos, together with ionomycin activation (Io) after ICSI. Interspecific embryos resulted in high rates of blastocysts that were not positively affected by Io activation: 32.6% vs 21% for Ch and Ch‐Io, 9.8% vs 21% for Leo and Leo‐Io, and 20% vs 17.4% for DC and DC‐Io. We also evaluated DNA‐fragmented nuclei of experiment 1 and 2 blastocysts, using TUNEL assay. The fragmented nucleus proportion was higher in the ITS‐5%O2 group, 67.6%. Surprisingly, interspecific blastocysts showed the lowest fragmented nucleus proportion: 27% and 29.9% for Ch and Leo, respectively. We concluded that ITS and 5%O2 improve blastocyst formation in DC, although with a concomitant increase in DNA fragmentation. Most importantly, cheetah and leopard spermatozoa were able to generate blastocysts without artificial activation, which suggests that developmental capacity of wild felid spermatozoa can be evaluated by interspecific ICSI. This technique should be used to assist wild felid reproduction. 相似文献
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NN Kuzma P Khandelwal SE Barrett LN Pfeiffer KW West 《Science (New York, N.Y.)》1998,281(5377):686-690
Optically pumped nuclear magnetic resonance (OPNMR) measurements were performed in two different electron-doped multiple quantum well samples near the fractional quantum Hall effect ground state nu = 13. Below 0.5 kelvin, the spectra provide evidence that spin-reversed charged excitations of the nu = 13 ground state are localized over the NMR time scale of about 40 microseconds. Furthermore, by varying NMR pulse parameters, the electron spin temperature (as measured by the Knight shift) could be driven above the lattice temperature, which shows that the value of the electron spin-lattice relaxation time tau1s is between 100 microseconds and 500 milliseconds at nu = 13. 相似文献
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V Pellegrini A Pinczuk BS Dennis AS Plaut LN Pfeiffer KW West 《Science (New York, N.Y.)》1998,281(5378):799-802
Inelastic light scattering by low-energy spin-excitations reveals three distinct configurations of spin of electron double layers in gallium arsenide quantum wells at even-integer quantum Hall states. The transformations among these spin states appear as quantum phase transitions driven by the interplay between Coulomb interactions and Zeeman splittings. One of the transformations correlates with the emergence of a spin-flip intersubband excitation at vanishingly low energy and provides direct evidence of a link between quantum phase transitions and soft collective excitations in a two-dimensional electron system. 相似文献