Results 21 to 30 of about 21,183 (172)
Nitrogen Transports and Transformations in Mangrove Sediments using Nitrogen Isotope Techniques in China [PDF]
, 2012 人类活动对生态系统的影响日益扩大，过量施肥、化石燃料的燃烧等引发的氮(N)负荷迅速增加。陆地生态系统过剩的N通过流域汇集至河口和海岸，威胁着海洋生态系统的健康。目前，全球N循环正致力于揭示河口和海岸地区N的源汇格局及主导机制。红树林湿地广泛分布于热带、亚热带河口和海岸地区，作为陆源营养盐入海过渡带，在缓解陆源N输入方面扮演着重要角色，成为了研究的热点。 本研究利用N稳定同位素技术，将现场培养与室内模拟培养相结合，揭示了我国东南沿海典型河口和海湾红树林湿地沉积物总氮沉积、固氮作用、反硝化作用 ...
李颖
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Hobbyist preferences for pet freshwater turtles
Conservation Biology, EarlyView.Abstract The burgeoning pet trade is a primary threat to wild freshwater turtles worldwide. Although the risks from commercial exploitation of turtles have been discussed widely, there is little empirical research on preferences for pet turtles from a hobbyists’ perspective.
Jingjing Zhao +7 more
wiley +1 more source
Shuitu Baochi Xuebao, 2003 在分析土壤水分特征曲线经验模型中特征参数的基础上，选取5种不同质地土壤，利用张力计测定了土壤水分特征曲线，根据实验资料确定了土壤水分特征曲线经验模型中参数，采用回归分析方法建立了参数与土壤物理特性间的函数关系，为采用土壤颗粒组成等土壤物理特性确定土壤水分特征曲线提供了指导。
来剑斌 王全九
doaj +2 more sources
Nonlinear finite element analysis for seismic performance of high-strength concrete beam-column joints with new reinforcement details [PDF]
, 2006 Because the factors that affect the behavior of the beam-column joints are complicated, an experimental study alone is not sufficient. Therefore, a nonlinear finite element analysis was conducted to provide better understanding of the performance of the ...
Gan, L, Li, J, Pam, HJ
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A review on the estimation of Secchi disk depth by remote sensing in inland and nearshore case 2 waters [PDF]
, 2015 自1865年,意大利天文学家Pietro Angelo Secchi发明塞克盘(Secchi disk)以来,使用塞克盘测量水体透明度迄今已有近150 a的历史。透明度(Secchi disk depth)是指放入水中的塞克盘能够看得见的最大深度[1]。它是描述水体光学性质的基本参数之一,也是水质调查中的一个重要指标 ...
施平, 禹定峰, 邢前国
core +1 more source
Conservation Biology, EarlyView.Abstract Recognition and engagement of Indigenous Peoples and local communities (IP&LCs) and other traditional knowledge (TK) holders in formal biodiversity governance remain limited, despite their significant contribution to the conservation and sustainable use of biodiversity through their knowledge, innovations, practices, and land stewardship.
Kinga Öllerer +8 more
wiley +1 more source
Gaoya dianqi, 2012 笔者提出一种新型单相并联混合型电力滤波方案。该方案采用磁通补偿原理和谐波电流分流技术,可以进一步降低APF所需容量,并有效改善滤波系统的性能。为分析该方案的相关特性,文中建立了它的稳态及暂态过程数学模型。重点分析PID控制器比例、积分、微分参数kp、ki、kd对暂态过程中的滤波特性和APF所需容量的影响,分析结果表明,控制器参数设置对滤波器暂态特性有重要影响,该分析为PID参数的设计提供了一定的理论参考。
刘卫民, 樊越甫, 刘方
doaj
Karyotype analysis of diploid oat germplasm introduced from Canada [PDF]
, 2014 The chromosome karyotype of three diploid oat species was studied with squash method. The results showed that the karyotype formula of Avena strigosa was 2 n =2 x = 14 = 10 m + 4 sm(2SAT),with metacentric and submetacentric chromosomes,1 pair of ...
Liu, W., Wu, B., Zhang, Z.
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Conservation Biology, EarlyView.Abstract Achieving global conservation policy goals requires the ability to set and measure progress toward science‐based targets for biodiversity. The species threat abatement and restoration (STAR) metric was developed to enable actors to set science‐based targets for species.
Louise Mair +17 more
wiley +1 more source
Development on Grinding Software of Solid Carbide End-Mill used for Aviation Aluminum Alloy Processing [PDF]
, 2015 刀具在机械制造业中占有相当重要的地位，伴随着国内航空航天领域的快速发展，特别是随着我国大型客机、军用飞机等国家重点项目的启动，航空铝合金加工专用刀具的需求量急剧增加。虽然国内刀具厂商和学者开展了大量研究工作，但是制造出的高性能刀具依然不能够满足航空高端制造的需求，国内高档航空铝合金刀具市场基本上被国外刀具企业垄断，严重制约着我国航空航天工业的进步和发展。 在此背景下，论文围绕着“面向航空铝合金加工用整体硬质合金铣刀磨制软件开发”课题开展了研究，基于刀具复杂曲面建模及成形理论 ...
陈站
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