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51.
Carbon nanotube quantum resistors 总被引:1,自引:0,他引:1
The conductance of multiwalled carbon nanotubes (MWNTs) was found to be quantized. The experimental method involved measuring the conductance of nanotubes by replacing the tip of a scanning probe microscope with a nanotube fiber, which could be lowered into a liquid metal to establish a gentle electrical contact with a nanotube at the tip of the fiber. The conductance of arc-produced MWNTs is one unit of the conductance quantum G0 = 2e2/h = (12.9 kilohms)-1. The nanotubes conduct current ballistically and do not dissipate heat. The nanotubes, which are typically 15 nanometers wide and 4 micrometers long, are several orders of magnitude greater in size and stability than other typical room-temperature quantum conductors. Extremely high stable current densities, J > 10(7) amperes per square centimeter, have been attained. 相似文献
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WA Snowdon 《Australian veterinary journal》1994,71(6):187-187
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GF Mastromonaco E Semple C Robert GJ Rho DH Betts WA King 《Reproduction in domestic animals》2004,39(6):462-467
Important differences exist between in vitro fertilized (IVF) and nuclear transfer (NT) bovine embryos. Studies have shown that although in vitro development is comparable, post-implantation survival is greatly reduced in NT embryos. In this study, we compare serum and bovine serum albumin (BSA) supplementation during oocyte maturation and embryo culture of IVF and NT embryos. In experiment 1, oocytes and embryos were randomly distributed into different treatment groups consisting of synthetic oviductal fluid (SOF) medium supplemented with either serum, fatty acid-free BSA (FAF) or fraction V BSA during maturation and/or culture to assess IVF embryo development. In experiment 2, oocytes were matured in SOF + serum or SOF + FAF and reconstructed embryos were cultured in SOF + FAF to assess NT embryo development. Among the IVF treatment groups, a greater number of blastocysts were observed in the steer serum (SER) group (IVM and IVC in SOF + serum) on day 6; however, no significant differences were seen in blastocyst development from day 8 onwards. Hatching frequencies on days 8 and 9 were significantly greater in groups with serum, with the exception of FAF (IVM and IVC in SOF + FAF) on day 9. For the NT treatment groups, the presence of serum during IVM resulted in a higher proportion of MII oocytes and increased blastocyst development and hatching rates were compared with supplementation of FAF. These results indicate that both serum and FAF provide comparable embryo development for IVF but not for NT bovine embryos. 相似文献
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SUMMARY Forty cats with hyperthyroidism were treated using 200 to 300 (typically 250) mBq of orally administered 131I. Thirty-six cases (90%) were successfully treated, as assessed by resolution of clinical signs and reduction In plasma thyroxine concentrations to normal or reduced values after treatment. Although higher doses of 131I appear to be required when the radioisotope is administered orally rather than Intravenously, a less stressful administration procedure and greater availability of therapy capsules offer useful advantages for treating thyrotoxic cats. 相似文献
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Efficiency of cloning has remained low and in spite of attempts to improve this technology, many reconstructed embryos do not implant or are lost during early pregnancy. Chromosomal aberrations, deviant gene expression patterns and abnormal regulation of cell death may be involved in this increased early embryonic loss. Here, we investigate the chronological onset of both apoptotic changes in nuclear morphology and DNA degradation [detected by transferase-mediated dUTP nick-end labelling (TUNEL) reaction] in bovine two-cell- to blastocyst-stage embryos. Such embryos were generated either by reconstruction with nuclear transfer from quiescent granulosa cells or by regular in vitro embryo production. Nuclear condensation was observed from the two-cell stage and TUNEL labelling was observed from the six-cell stage in reconstructed embryos, whereas nuclear condensation was evident from the eight-cell stage and TUNEL labelling from the 13-cell stage in embryos derived in vitro. Furthermore, reconstructed embryos displayed elevated ratios of embryos containing apoptotic nuclei at pre-compaction stages and higher indices of apoptotic nuclei in morula and blastocyst stages when compared with in vitro-produced embryos. 相似文献
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本研究旨在探讨马铃薯藤饲喂水平对山羊生长性能、养分消化率和胴体特征的影响。试验将平均初始体重为(14.42±0.24)kg的40头山羊随机分为4组,每组5个重复,每个重复2头。T1组仅饲喂干草,T2组饲喂干草+100%马铃薯藤,T3组饲喂干草+50%马铃薯藤+50%浓缩料,T4组饲喂100%浓缩料。在为期10周的饲养试验后屠宰,分析胴体特征。结果:T2~T4组山羊的末重、增重、日增重和饲料效率显著高于T1组(P<0.05),其中T1组山羊的日增重和增重均表现出负增长。T2~T4组山羊的干物质、有机物、粗蛋白质和代谢能摄入量均显著高于T1组(P<0.05),但T2和T3组山羊中性洗涤纤维摄入量显著高于T1和T4组(P<0.05)。T2、T3和T4组山羊干物质和有机物表观消化率显著高于T1组(P<0.05),T4组山羊粗蛋白表观消化率显著高于T1和T2组(P<0.05)。T2、T3和T4组山羊屠体重、热胴体重、眼肌面积、可食用内脏和不可食用内脏重量均显著高于T1组(P<0.05)。T3组山羊的屠宰率显著高于其他组(P<0.05)。结论:在干草为基础的日粮中添加马铃薯藤可以提高山羊采食量、饲料转换率、养分消化率、屠宰率和胴体特征。
[关键词]马铃薯藤|山羊|生长性能|消化率|胴体特征 相似文献