Results 1 to 10 of about 1,214,007 (162)

不同土壤水分条件下侧柏幼苗的生理活动及氮素分配策略

open access: yesShuitu Baochi Xuebao, 2020
以北京地区3年生侧柏幼树为研究对象,采用温室内盆栽试验,设置5个不同土壤含水量水平,采用15N同位素自然丰度法研究不同水分条件下侧柏幼苗的生理活动、生物量分配及氮素吸收和分配情况。结果表明:(1)在水分胁迫下,侧柏单株净光合速率、呼吸速率、蒸腾速率均表现为最低值,随着干旱胁迫解除,含水量增加到正常值,各指标分别增加为原来的4.86,3.74,7.29倍,叶片含水量和叶面积分别增加了24.37%,23.69%;之后当土壤含水量超过正常值时,随着土壤水分含量的进一步增加,各指标略有下降。(2)在水分胁迫下 ...
王鑫   +5 more
doaj  

Alleviation of phosphorus rather than nitrogen limitation driven by permafrost and landscape effects on Dahurian larch forests

open access: yesFunctional Ecology, EarlyView.
Read the free Plain Language Summary for this article on the Journal blog. Abstract Permafrost thaw is reshaping nutrient dynamics in boreal forests, but its impacts on tree nutrient limitation and functional strategies remain poorly understood. Clarifying these responses is crucial for predicting the response of boreal forests to climate change.
Qiyue Fu   +9 more
wiley   +1 more source

Spatial identification of areas suitable for other effective area‐based conservation measures in the European Union

open access: yesConservation Biology, EarlyView.
Abstract Although significant biodiversity has been safeguarded by protected areas (PAs), biodiversity trends continue downward. Within the frameworks of the EU Biodiversity Strategy for 2030 and the new EU Restoration Regulation (2024), conserving critical biodiversity areas is essential.
George Kefalas   +14 more
wiley   +1 more source

旱稻叶片含氮量与水分含量的定量关系

open access: yesShuitu Baochi Xuebao, 2006
在池栽条件下研究了不同水分处理对早稻叶片氮素含量以及叶片组织水势、自由水和束缚水含量的影响。结果表明:在不同土壤水分条件下,植株全氮含量基本上表现为先下降而后升高再下降的变化趋势,随土壤含水量增加叶片中全氮含量逐渐减少,叶片的组织水势和自由水含量逐渐增大,束缚水含量逐渐下降。叶片氮素含量与分蘖高峰期(播种后40~46d)的组织水势呈显著负相关。叶片氮素含量(y)与叶片组织水势(z)间存在y=-0.6999x+2.3764的显著直线回归定量关系。
赵全志   +5 more
doaj   +2 more sources

Representation of obligate groundwater‐dwelling copepod diversity in European protected areas

open access: yesConservation Biology, Volume 40, Issue 3, June 2026.
Abstract Groundwaters sustain diverse surface ecosystems and are populated by metazoan species, mostly invertebrates, that provide fundamental ecological functions and are often of prominent conservation value due to narrow endemism and high phylogenetic rarity.
Francesco Cerasoli   +7 more
wiley   +1 more source

The Acceleration of Phase Transformation and Strength–Toughness Match by Cerium Addition for Low‐Temperature Bainite

open access: yesRare Metals, Volume 45, Issue 5, May 2026.
ABSTRACT The engineering application of traditional nano‐bainite steel, also known as low‐temperature bainite steel, has been restricted due to its relatively low toughness and the prolonged isothermal transformation time during manufacturing processes.
Jin‐Zhou Zhang   +7 more
wiley   +1 more source

Superior Abrasibility of YSZ(ESP)/BN@ZrO2‐Polyester Composite Sealing Coating Reinforcing With Hybrid Micron/Nanometer Multiscaled Pore Structure

open access: yesRare Metals, Volume 45, Issue 5, May 2026.
ABSTRACT Composite materials hold significant potential for abrasive sealing, yet composite materials used for abrasive sealing fall short in service durability under extreme environments. Here, a controllable strategy for adjusting pore structure is proposed, aiming to design a YSZ(ESP)/BN@ZrO2‐polyester coating with hybrid micron/nanometer ...
Shuang Yu   +8 more
wiley   +1 more source

榆林沙区土壤水分时空格局及动态变化规律研究

open access: yesShuitu Baochi Xuebao, 2008
采用定位取样与烘干法,测定了榆林沙区几个树种土壤含水量。结果表明:各树种土壤含水量变化规律为:樟子松>柠条>紫穗槐>沙柳>沙蒿>花棒-踏郎;土壤含水量的垂直分布格局为表层土壤含水量最低,随着土壤深度的增加,土壤含水量呈增加趋势;土壤含水量的季节动态规律为不同树种土壤含水量具有明显的季节变化规律,土壤含水量按季节变化可分为3个阶段,4-5月的土壤水分弱失水阶段,6-8月的土壤水分消耗阶段,9-10月的土壤水分缓慢恢复阶段。
尚爱军   +4 more
doaj  

Phosphotungstic Acid Modulated PNIPAM/P(AA‐co‐AM) Bilayer Hydrogels With Programmable Thermo‐Responsive Kinetics and Enhanced Toughness

open access: yesRare Metals, Volume 45, Issue 5, May 2026.
ABSTRACT Thermo‐responsive hydrogels based on poly(N‐isopropylacrylamide) (PNIPAM) are promising candidates for soft actuation, yet their practical applications are often constrained by sluggish thermo‐responsive kinetics and insufficient mechanical robustness.
Hui Liu   +5 more
wiley   +1 more source

基于频域介电谱法研究甲酸对油纸绝缘水分评估的影响

open access: yesGaoya dianqi, 2019
为了准确评估油纸绝缘中的水分含量,研究小分子酸对油纸绝缘水分评估的影响,文中制备了多组不同水分和甲酸含量的油浸纸试样并利用频域介电谱法对其进行FDS测试,基于此提出表征不同酸性环境下油纸绝缘水分含量的特征参量。研究结果表明:水分会影响小分子酸在油纸间的分布,且随着绝缘纸水分含量和油中甲酸含量的增加,油浸纸试样tanδ频域谱在10?3~101显著增大。相较于无酸环境,甲酸含量的增加使油浸纸试样同一水分含量下的tanδ频域谱发生不同程度的增加,实际测量绝缘纸水分含量时小分子酸的影响不容忽视 ...
高波, 许竟, 夏国强, 吴广宁
doaj  

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