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101.
102.
Evaluation of the damage in fish spermatozoa cryopreservation 总被引:4,自引:0,他引:4
Cryodamages occur during sperm cryopreservation. Cryopreservation of fish sperm usually results in marked decrease in sperm quality, such as swelling or disruption of the plasma membrane, mitochondrial dysfunction, diminished sperm motility, impaired velocity, shorter motility period, denaturation, and release of some enzymes from spermatozoa. In this paper, damages in morphology, physiology, biochemistry and metabolism, and genetic integrity of fish semen after cryopreservation are discussed. New approaches in assessment of fish thawed sperm quality such as computer assisted sperm analysis, flow cytometic analysis combined with fluorescent probes and single cell gel electrophoresis are also briefly reviewed. 相似文献
103.
Yusuke Yamazaki Jumpei Kubota Tetsuo Ohata Varely Vuglinsky Takahisa Mizuyama 《水文研究》2006,20(3):453-467
We attempted to clarify the runoff characteristics of a permafrost watershed in the southern mountainous region of eastern Siberia using hydrological and meteorological data obtained by the State Hydrological Institute in Russia from 1976 to 1985. We analysed seasonal changes in the direct runoff ratio and recession gradient during the permafrost thawing period. Thawing depth began to increase from the beginning of May and continued to increase until the end of September, exceeding 150 cm. Annual precipitation and discharge were in the range 525–649 mm and 205–391 mm respectively. The sum of the annual evapotranspiration and changes in water storage ranged from 235 to 365 mm. The mean daily evapotranspiration in June, July, August and September was 1·5 mm day?1, 1·7 mm day?1, 1·5 mm day?1, and 0·5 mm day?1 respectively. The direct runoff ratio was highest in June, decreasing from 0·8 in June to 0·2 in September. The recession gradient also decreased from June to September. Since the frozen soil functioned as an impermeable layer, the soil water storage capacity in the thawing part of the soil, the depth of which changed over time, controlled the runoff characteristics. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
104.
The practice of building and operating of railroad beds shows that the greatest at enuation of soils occurs in the spring, during their transition from the frozen to thawed state. The greatest influenc... 相似文献
105.
沉积岩中自生粘土矿物分离提纯方法的改进 总被引:2,自引:2,他引:2
尝试了一种从沉积岩中分离提纯自生粘土矿物的方法-反复冷冻-解冻法,其改进之处在于利用渗透于岩石样品中的水,在冷冻的情况下体积膨胀,而使岩石颗粒散开,用改进的岩样碎样法分离出的粘土矿物,经X射线衍射分析鉴定证实,在<1μm粒级时,粘土组分中不含有碎屑的钾长石,而常规法做不到这一点。 相似文献
106.
新疆地区水工建筑物冻害防治概述 总被引:1,自引:1,他引:1
通过对新疆地区水工建筑物冻害的观测与调查,结合有关资料,提出了冻胀防治措施,供今后修建水利工程时参考。 相似文献
107.
The thawing-melting of the permafrost damages the subground of highways on the Qinghai-Tibet Plateau. With the application of ground-penetrating-radar (GPR) technology, the maximum permafrost melting interface can be effectively distinctly differentiated and imaged. A hierarchical feature of the permafrost region is shown clearly on the imaging profile of GPR data. The complete ablation zone or part of it is displayed distinctly. In addition, the details of subsurface layers can be effectively characterized by GPR attribute-analysis technology. With the attribute calculation and filter, the instantaneous amplitude, instantaneous frequency, and relative wave impedance can be applied in a more efficient way to divide the complete ablation zone, part of the ablation and non-ablation interface. The relative distribution of water content in a seasonally thawing permafrost region can be obtained through a comprehensive GPR attribute analysis. 相似文献
108.
The Surface Energy Budget and Its Impact on the Freeze-thaw Processes of Active Layer in Permafrost Regions of the Qinghai-Tibetan Plateau 总被引:1,自引:0,他引:1
Junjie MA Ren LI Hongchao LIU Zhongwei HUANG Tonghua WU Guojie HU Yao XIAO Lin ZHAO Yizhen DU Shuhua YANG 《大气科学进展》2022,39(1):189-200
The surface energy budget is closely related to freeze-thaw processes and is also a key issue for land surface process research in permafrost regions.In this study,in situ data collected from 2005 to 2015 at the Tanggula site were used to analyze surface energy regimes,the interaction between surface energy budget and freeze-thaw processes.The results confirmed that surface energy flux in the permafrost region of the Qinghai-Tibetan Plateau exhibited obvious seasonal variations.Annual average net radiation(Rn)for 2010 was 86.5 W m-2,with the largest being in July and smallest in November.Surface soil heat flux(G0)was positive during warm seasons but negative in cold seasons with annual average value of 2.7 W m-2.Variations in Rn and G0 were closely related to freeze-thaw processes.Sensible heat flux(H)was the main energy budget component during cold seasons,whereas latent heat flux(LE)dominated surface energy distribution in warm seasons.Freeze-thaw processes,snow cover,precipitation,and surface conditions were important influence factors for surface energy flux.Albedo was strongly dependent on soil moisture content and ground surface state,increasing significantly when land surface was covered with deep snow,and exhibited negative correlation with surface soil moisture content.Energy variation was significantly related to active layer thaw depth.Soil heat balance coefficient K was>1 during the investigation time period,indicating the permafrost in the Tanggula area tended to degrade. 相似文献
109.
在青藏铁路冻土路基现场实测资料的基础上,用改进的BP神经网络建立起了路基变形与地温、路基高度和上限之间的非线性映射。对某一典型路基第30年的变形进行了预测,结果显示路基的累计融沉量在冻胀量的两倍以上。从绘制的路基变形过程曲线可以很清晰地看出路基一年中的变形趋势和冻胀融沉区间。在4月份以后,路基的变形由冻胀向融沉转变,变形与地温有很好的正比关系,但是当地温升高到一定值时,路基的融沉量便不再随着地温的升高而增大。路基的冻胀与地温的关系也有相似的规律,说明地温对路基变形的影响存在一个比较明显的区间,在这个区间范围内的温度对路基变形的影响较大,这为控制路基的病害提供了一个比较有价值的信息。 相似文献
110.
The paper features the results of field measurements and numerical research of embankment behaviour in permafrost soils of Transbaikalia railway section following implementation of preventive works to eliminate action of heaving forces on the main area of embankment subgrade. 相似文献