Results 1 to 10 of about 1,306,529 (154)

昭通绒鼠夏冬季节体重和产热特征的变化

open access: yes野生动物学报, 2021
为探究昭通绒鼠(Eothenomys olitor)体重和产热特征的季节性变化,对其夏季和冬季的体重、体脂重量、摄食量、静止代谢率(RMR)、非颤抖性产热(NST)、血清瘦素质量浓度、内脏器官和消化道重量、肝脏和褐色脂肪组织(BAT)中的生化指标以及下丘脑神经肽Y(NPY)、刺鼠相关蛋白(AgRP)、阿片促黑色素原(POMC)和可卡因-安他非明转录调节肽(CART)基因表达量进行测定。结果显示:昭通绒鼠夏冬两季体重差异不显著,但体脂重量夏季较高,冬季较低;摄食量、RMR和NST均是冬季高于夏季 ...
杨押佐 1 贾婷 2 张浩 1 王政昆 1 朱万龙 1
doaj   +1 more source

张衡一号卫星探测的赤道附近电场分布及其与电离层分布的关系

open access: yesKongjian kexue xuebao, 2023
利用张衡一号卫星搭载的电场探测仪(Electric Field Detector,EFD)获得的VLF频段2019年电场功率谱数据,研究赤道附近区域近东西向电场的背景分布、季节变化以及与电离层背景的关系。结果表明:白天电场背景在赤道及其附近随季节呈不同波形结构,以3波、4波为主;夜间电场背景规律性稍差,仍呈随季节变化的经向波形结构分布特征;白天电场背景与电离层背景的季节变化呈高度正相关性,春秋季为峰值;夜间电场背景的季节变化特征是夏冬季峰值,与夜间电离层背景整体上呈负相关性 ...
何 宏玮   +5 more
doaj   +1 more source

四川地区地震背景噪声特征分析

open access: yesDizhen xuebao, 2021
选取四川省数字测震台网2015年1月1日至2018年12月31日期间60个固定台站的三分量连续波形记录,计算了台站噪声加速度功率谱密度及相应的概率密度函数分布,统计了不同频率下的噪声功率谱密度值分布,对不同区域、不同频率下背景噪声水平的变化特征予以分析。结果表明:大部分地震台站的高频段噪声由于受到台站附近人为的、规律的作息生活和生产方式的影响,呈现明显的季节性变化和日变化,即夏季噪声水平升高,冬季降低,在农历春节期间达到全年最低值,地理空间分布特征不明显;第二类地脉动冬季噪声水平升高,夏季降低 ...
Jiangtao Xie   +3 more
doaj   +1 more source

黄河干流头道拐水文站水沙运动特征及影响因素

open access: yesShuitu Baochi Xuebao, 2021
为明确黄河干流头道拐水文站水沙运动过程、变化趋势及运动状态特征,以2006—2018年黄河干流头道拐水文站水沙数据为基础,基于累积距平法、R/S极差分析法、河道来沙系数与不协调度等研究方法,对头道拐水文站水沙运动过程进行系统分析。结果表明:头道拐水文站年际间径流与输沙量和年内月均径流与输沙量变化趋势均呈现良好的一致性,但两者的季节性差异特征显著,且输沙量的显著性较径流更突出;冬季径流与输沙量变化趋势同步性相比其他季节较差 ...
赵水霞   +6 more
doaj  

Extreme site fidelity in long‐distance migratory shorebirds in Australia and potential implications for conservation

open access: yesConservation Biology, EarlyView.
Abstract Site fidelity is the tendency for animals to repeatedly return to the same locations, either within or between years. Site fidelity enables animals to utilize knowledge of previously visited locations, including assessments of seasonal variations in health and mortality risks (e.g., predation), resource availability, and social benefits such ...
Tobias A. Ross   +13 more
wiley   +1 more source

Intact coastal nursery rearing amid climate‐driven phenological shifts in threatened salmon

open access: yesConservation Biology, EarlyView.
Abstract Literature linking phenology to climate has proliferated in recent decades and shows that climate change has reorganized seasonal opportunities worldwide. However, this literature often quantifies changes in point measures of timing (e.g., beginnings and peaks) without context about duration (e.g., rearing season length) or performance (e.g ...
Stuart H. Munsch   +8 more
wiley   +1 more source

From Indicator to Prediction: Five Decades of Biochemical Oxygen Demand Research in Tropical Freshwaters

open access: yesWorld Water Policy, Volume 12, Issue 4, November 2026.
ABSTRACT Biochemical oxygen demand (BOD) remains a core indicator of organic pollution in freshwater monitoring, but its role in water policy and practice is changing as water‐quality assessment moves toward predictive, integrative, and decision‐support approaches.
Isadora Favero Roque Cenci   +5 more
wiley   +1 more source

晋西人工防护林乡土树种抗旱性研究

open access: yesShuitu Baochi Xuebao, 2000
应用压力室技术对晋西北7个乡土造林树种的水分参数进行了研究,分析了各树种的抗旱性及其季节变化规律。结果表明:(1)各树种抗旱性具有一定的季节变化格局,根据本地区气候变化特征,其基本规律是:生长季初期最弱,炎热干旱的季节有所增强,降水峰期再次减弱,而到生长季末期则是一年中抗旱性最强的时期。(2)应用抗旱性综合指标判定7个树种抗旱性强弱,其顺序依次为:山杏,海红,榆树,刺槐、沙刺,红柳,沙枣。(3 ...
柴宝峰 王孟本
doaj   +2 more sources

Habitat and spatial trends of U.K. wintering waterbird populations over 50 years

open access: yesConservation Biology, Volume 40, Issue 5, October 2026.
Abstract The United Kingdom is an important wintering ground for millions of waterbirds. Most U.K. wintering waterbird populations increased between 1970 and the mid‐1990s, but declined thereafter. We examined U.K. population indices in 46 wintering waterbird species in two 25‐year periods, 1970–1994 and 1995–2019, to identify which waterbird groups ...
Blaise Martay   +8 more
wiley   +1 more source

光周期对雄性哺乳动物季节性精子发生的影响及其调控机制

open access: yes野生动物学报, 2022
季节性繁殖是哺乳动物在长期的进化过程中,为了应对外界环境的变化,选择合适的季节进行繁殖的行为。雄性哺乳动物在非繁殖季节表现为睾丸退化,精子发生的减数分裂过程受阻,进入繁殖季节性腺恢复,重新启动精原细胞的分裂和分化,这种季节性精原细胞分裂和分化与精子发生受到环境因子和多种体内激素的调节。就光周期信号分子——褪黑激素通过TSH-DIO2/DIO3-T3逆行通路和HPG轴—睾酮—视黄酸信号系统对雄性哺乳动物繁殖季节性调控的研究综述可知:褪黑激素通过调控HPG轴的功能促进精子的发生 ...
杨 笛, 陈婉依, 宫泽儒, 杨 明
doaj  

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