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991.
根据不同类型岩浆岩的岩石密度、磁性的不同,通过应用RGIS软件和Surfer软件对重磁异常分离、延拓、求导及重、磁特征信息的复合处理等,研究了小秦岭岩浆岩地球物理特征,结果表明:重磁反映岩浆岩带所处的构造单元部位、岩浆系列特征以及与矿带的时空关系,由此可将小秦岭划分为4段不同的岩性岩浆岩。 相似文献
992.
Zeqing Ma Henrik Hartmann Huimin Wang Qingkang Li Yidong Wang Shenggong Li 《European Journal of Forest Research》2014,133(2):307-321
Afforestation and ecological restoration have often been carried out with fast-growing exotic tree species because of their high apparent growth and yield. Moreover, fast-growing forest plantations have become an important component of mitigation measures to offset greenhouse gas emissions. However, information on the long-term performance of exotic and fast-growing species is often lacking especially with respect to their vulnerability to disturbance compared to native species. We compared carbon (C) storage and C accumulation rates in vegetation (above- and belowground) and soil in 21-year-old exotic slash pine (Pinus elliottii Engelm.) and native Masson pine (Pinus massoniana Lamb.) plantations, as well as their responses to a severe ice storm in 2008. Our results showed that mean C storage was 116.77 ± 7.49 t C ha?1 in slash pine plantation and 117.89 ± 8.27 t C ha?1 in Masson pine plantation. The aboveground C increased at a rate of 2.18 t C ha?1 year?1 in Masson pine and 2.23 t C ha?1 year?1 in slash pine plantation, and there was no significant difference in C storage accumulation between the two plantation types. However, we observed significant differences in ice storm damage with nearly 7.5 % of aboveground biomass loss in slash pine plantation compared with only 0.3 % loss in Masson pine plantation. Our findings indicated that the native pine species was more resistant to ice storm because of their adaptive biological traits (tree shape, crown structure, and leaf surface area). Overall, the native pine species might be a safer choice for both afforestation and ecological restoration in our study region. 相似文献
993.
实验分离提取杨凌媚丽葡萄新酒中的香气糖苷,添加优选野生胶红酵母的糖苷酶液,进行催化水解实验,萃取水解生成的品种香气成分,进行GC-MS检测分析。以杏仁β-糖苷酶、黑曲霉果胶酶、La Fort商业果胶酶作催化比较实验。结果表明,杏仁β-糖苷酶标准品催化水解生成的游离香气成分种类和含量最多,其次是野生胶红酵母酶液和黑曲霉果胶酶。酶促水解生成的游离成分中,萜烯类和去甲类异戊二烯化合物能够赋予葡萄酒果香和花香,微量的酚酸酯可增加香气的复杂性,而含量很高的脂肪族类化合物和挥发性酚类会带给葡萄酒不良气味。因此,具有中等催化水解香气糖苷能力的野生胶红酵母的糖苷酶具有良好的增香酿造应用潜力。 相似文献
994.
995.
有机污染在时间上的变化为,7月前呈有机污染不断加剧的过程,到7月整个东流区均达到严重污染水平;7月后是污染程度逐渐减轻的过程,到9月整个东流区水质恢复到较好水平。有机污染程度在空间上的变化是从湾外向湾内逐渐加剧趋势。6、7和8月整个东流区均达到富营养化水平,但富营养化的程度有所不同,7月富营养化程度最严重,8月较7月减轻,到9月湾内基本恢复正常。与1994年8月比较,1995年8月东流区有机污染和富营养化程度有所加剧。 相似文献
996.
Eric Saillant Liang Ma Xiaoxue Wang Delbert M Gatlin III & John R Gold 《Aquaculture Research》2007,38(8):781-788
Heritability of juvenile growth rate was estimated for red drum (Sciaenops ocellatus), an economically important sciaenid fish in the southern USA. Thirty‐eight families were generated via ‘natural’ spawning of multiple sets of five breeders (three dams × two sires) in individual brood tanks. Offspring were individually tagged with Passive Integrated Transponder (PIT) tags and mixed for grow‐out in replicate ‘common‐garden’ tanks. Juvenile growth was followed from 166.4±18.6 to 254.0±27.0 mm (total length). Offspring were assigned a posteriori to individual brood fish (dam and sire) based on genotypes at nuclear‐encoded microsatellites. Heritability (h2) of a thermal growth coefficient was estimated using an animal‐additive model and a restricted maximum‐likelihood algorithm. Estimates of h2 were 0.33±0.08 and 0.31±0.08 for thermal growth coefficient based on length and weight respectively. These results indicate a significant genetic component in juvenile growth rate in red drum. Estimates of h2 for condition coefficient (K) at various measurement dates averaged 0.38, suggesting a genetic component to shape in juvenile red drum. 相似文献
997.
998.
Sylvie Dufour Maïté Montero Nadine Le Belle Marc Bassompierre Judy A. King Robert P. Millar Richard E. Peter Yves-Alain Fontaine 《Fish physiology and biochemistry》1993,11(1-6):99-106
Using specific radioimmunoassays for the two GnRH molecular forms present in the European eel, Anguilla anguilla, (mGnRH and cGnRH II), we compared their distributions in the pituitary and different parts of the brain of female silver eels, as well as the modifications of their levels in experimentally matured female eels (treated with carp pituitary extract). In control eels, mGnRH levels were higher than cGnRH II levels in the pituitary, olfactory lobes and telencephalon, di- and mesencephalon, while the opposite was found in the posterior part of the brain (met- and myelencephalon). Experimental sexual maturation of the gonads significantly increased mGnRH levels in the pituitary and anterior parts of the brain; such a positive effect was not observed on the low cGnRH II levels, which were, in contrast, reduced. These data indicate that the positive feedback of gonadal hormones on GnRH, that we previously demonstrated, would specifically affect the mGnRH form. The differential distribution and control of mGnRH and cGnRH II suggest that these two forms have different physiological roles in the eel. The large increase in mGnRH during sexual maturation suggests the prime implication of this form in the neuroendocrine control of reproduction. 相似文献
999.
在臻头河下游放置规格为9米×9米×2.5米的网箱养殖花鲢,每箱投放规格为400~600g/尾的大规格鱼种1500尾,经7个月的养殖,10个网箱共产花鲢35880公斤,规格2.6公斤/尾。投入产出比1∶2.5。 相似文献
1000.