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51.
甘肃畜牧业生产潜力及开发利用 总被引:2,自引:1,他引:1
甘肃畜牧业生产潜力及开发利用牛叔文(甘肃省国土整治农业区划研究所,兰州730000)RegionalDistributionAndExploitationofLivestockHusbandryPrOductivityinGansuProvince¥... 相似文献
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Richard R. Montanucci 《Zoo biology》1989,8(2):139-149
Aspects of the reproduction and growth of Phrynosoma ditmarsi from Sonora, Mexico, were observed in captivity. Lizards were maintained indoors with a seasonally adjusted photoperiod. Mating occurred from August through December, with the majority of copulations observed in August, September, and October. Lizards were over-wintered between temperatures of 13°C and 16°C, with occasional drops to 8° C. The female reproductive cycle is not completely understood. Females may have stored sperm over the winter months, with ovulation and fertilization occurring in the following spring. Alternatively, embryogenesis may have been interrupted during the winter. Parturition occurred in June and July. Males became sexually mature at 13 months of age. Females first copulated at this age, resulting in the production of young at 24 months of age. Courtship and non-receptive behaviors were similar to those of other Phrynosoma. 相似文献
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Joo P.S. Correia 《Zoo biology》2001,20(5):435-441
On December 10, 2000, five tiger rockfish, Sebastes nigrocinctus, and 10 ratfish, Hydrolagus colliei, were transported from Vancouver, Canada, to Lisbon, Portugal, for 51 and 44 hours, respectively. The transport vessels consisted of large circular tanks (1.0‐m diameter × 0.6 m high) and filtration was added to the rockfish tank only. Filtration consisted of a combination of cartridge and activated carbon, powered by a 12‐V bilge pump placed on the middle of the transport vessel. Water quality parameters (ammonia, temperature, and oxygen saturation) were tested during the transport, and an ammonia detoxifier was added to some of the transport vessels when ammonia concentration reached 0.25 mg/L. Sodium bicarbonate was also added for pH buffering. All animals survived the trip and the subsequent 4 weeks. The water quality monitoring and treatment regimen therefore seemed appropriate for this type of long‐term transportation. Zoo Biol 20:435–441, 2001. © 2001 Wiley‐Liss, Inc. 相似文献
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Rik Van Bogaert Kristof Haneca Jan Hoogesteger Christer Jonasson Morgan De Dapper Terry V. Callaghan 《Journal of Biogeography》2011,38(5):907-921
Aim Models project that climate warming will cause the tree line to move to higher elevations in alpine areas and more northerly latitudes in Arctic environments. We aimed to document changes or stability of the tree line in a sub‐Arctic model area at different temporal and spatial scales, and particularly to clarify the ambiguity that currently exists about tree line dynamics and their causes. Location The study was conducted in the Torneträsk area in northern Sweden where climate warmed by 2.5 °C between 1913 and 2006. Mountain birch (Betula pubescens ssp. czerepanovii) sets the alpine tree line. Methods We used repeat photography, dendrochronological analysis, field observations along elevational transects and historical documents to study tree line dynamics. Results Since 1912, only four out of eight tree line sites had advanced: on average the tree line had shifted 24 m upslope (+0.2 m year?1 assuming linear shifts). Maximum tree line advance was +145 m (+1.5 m year?1 in elevation and +2.7 m year?1 in actual distance), whereas maximum retreat was 120 m downslope. Counter‐intuitively, tree line advance was most pronounced during the cooler late 1960s and 1970s. Tree establishment and tree line advance were significantly correlated with periods of low reindeer (Rangifer tarandus) population numbers. A decreased anthropozoogenic impact since the early 20th century was found to be the main factor shaping the current tree line ecotone and its dynamics. In addition, episodic disturbances by moth outbreaks and geomorphological processes resulted in descent and long‐term stability of the tree line position, respectively. Main conclusions In contrast to what is generally stated in the literature, this study shows that in a period of climate warming, disturbance may not only determine when tree line advance will occur but if tree line advance will occur at all. In the case of non‐climatic climax tree lines, such as those in our study area, both climate‐driven model projections of future tree line positions and the use of the tree line position for bioclimatic monitoring should be used with caution. 相似文献
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Naomi H. Bishop 《Human ecology: an interdisciplinary journal》1989,17(2):177-204
Transhumant herding of cow-yak hybrids is a specialization of Helambu Sherpa villagers living at altitudes between 7,000– 11,000 feet on the southern slopes of the Himalayas. Hybrids are ideally suited for the climate at this altitude, producing large quantities of rich milk for butter production. Focused on a village in east- central Nepal, this paper documents a shift by some families between 1971– 1989 from the longstanding pattern of herding hybrids to an alternative pattern of producing them. This involves learning to manage yak, establishing new transhumance routes, a switch from dairying to livestock production, and a variety of economic, environmental, and social repercussions. The two types of herding systems are described, and possible causes for the shift are discussed within the context of the economic options available to people in this environment. A special emphasis is placed on the flexibility of options that is both necessary and possible with transhumant agropastoralism as practiced by middle and high-altitude Himalayan peoples. 相似文献
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肠道微生物与宿主机体健康息息相关。粪便微生物移植(又称为粪菌移植,fecal microbiota transplantation,FMT)通过将健康供体粪便中的完整肠道菌群移入肠道微生态失衡的患者胃肠道内,经肠道菌群重构、恢复至正常状态。用FMT治疗某些肠道疾病如复发性艰难梭菌感染、溃疡性结肠炎、肠易激综合症、克罗恩病效果显著,且可能对因肠道菌群紊乱引起的肠道外疾病的治疗有潜在价值。本文主要对FMT技术的发展进程、在疾病上的研究以及在畜牧业上的应用潜能进行综述,并分析其应用的制约因素。 相似文献
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The domesticated zebra finch (Taeniopygia guttata) is a well‐established animal model for studying vocal learning. It is also a tractable model for developmental analyses. The finch genome has been sequenced and methods for its transgenesis have been reported. Hatching and sexual maturation in this species takes only two weeks and three months, respectively. Finch colonies can be established relatively easily and its eggs are laid at a stage earlier than in other common avian experimental models, facilitating the analysis of very early avian development. Representing the Neoaves to which 95% of all bird species belong, the finch can potentially complement two existing, Galloanserae developmental models, the chick, and quail. Here, we provide a step‐by‐step guide for how to set up a finch colony in a conventional laboratory environment. Technical tips are offered to optimize hens’ productivity and ensure a constant supply of fertilized finch eggs. Methods of handling finch eggs and embryos for subsequent embryological, cellular, or molecular analyses are also discussed. We conclude by emphasizing scientific values and cost effectiveness of maintaining a finch colony for avian developmental studies. genesis 53:669–677, 2015. © 2015 Wiley Periodicals, Inc. 相似文献