Results 121 to 130 of about 34,670 (224)
不同经济发展水平区域物流与经济增长的协整关系研究 [PDF]
根据协整检验和因果关系检验等计量方法,利用中国各省1991~2007年物流发展水平和国内生产总值的年度数据,将31个省(市、自治区)按经济密集度不同分成三大类地区,并对其物流和经济增长的关系分析进行了实证分析。实证结果表明:三个区域的物流与经济增长均存在协整关系,发达的一类地区两个变量存在双向Granger因果关系,而后两类地区两个变量仅存在单向的Granger原因。国家自然科学重点资助项目“中国城市化进程的资源环境基础研究 ...
张雷, 杨志梁, 程晓凌
core
Summary In plants, a key example of convergence is the repeated evolution of floral traits associated with the transition from outcrossing to self‐fertilization, often resulting in the ‘selfing syndrome’ (e.g. reduced flower size and loss of scent). However, potentially overlooked changes concern the pollen coat, which plays a role in different aspects
Ömer İltaş +7 more
wiley +1 more source
Trees in cities provide a great number of benefits to people and nature, but they are challenged by harsh conditions. Trees rely on helpful fungi in their roots to get essential nutrients from the soil, but we do not know which of these fungi are resistant to city landscapes.
Casper T. Verbeek +2 more
wiley +1 more source
Hierarchical Structured TiO2/Boron‐Doped Diamond for Efficient Photo‐Electrocatalytic Degradation
ABSTRACT The discharge of refractory organic dye wastewater poses a significant threat to the ecological environment, necessitating the development of efficient treatment technologies. Herein, a uniform TiO2 array (TiO2‐AR) electrode is fabricated using a combination of magnetron sputtering and a mask plate process with a boron‐doped diamond (BDD ...
Haiming Sun +10 more
wiley +1 more source
采用抛物线拟合方法计算大容量试验短路电流波形的峰值和对应的时间坐标。理论证明短路电流波形上相邻两峰值的时间坐标中点的电流值近似等于此时的直流分量值,并据此给出波形的直流时间常数、交流(基波)分量有效值和直流分量百分数的算法。使用STL提供的标准短路电流波形,对文中算法和现有算法进行了对比测试。测试结果验证了该算法的准确性,同时表明,仅使用3个峰值点并未显著降低文中算法在计算交流分量恒定的短路电流波形参数时的准确度。通过计算直流时间常数不同 ...
周小猛 +4 more
doaj
ABSTRACT This study demonstrates a new strategy for modifying the boron content to address stress‐relief cracking (SRC) in the 7CrMoVTiB10.10 alloy. First, coarse‐grained heat‐affected zone (CGHAZ) specimens with different boron contents were prepared via simulated welding thermal cycles.
Dongdong Zhang +3 more
wiley +1 more source
[Clinical application research of three-dimensional printed patient-specific cutting guides in Cole midfoot osteotomy]. [PDF]
Zhang Z +7 more
europepmc +1 more source
ABSTRACT Lithium‐selenium (Li‐Se) batteries have attracted considerable attention due to their high theoretical specific capacity and the intrinsically good electronic conductivity of selenium. Nevertheless, low active‐material utilization, parasitic side reactions, and sluggish reaction kinetics hinder their practical application.
Yanan Fu +8 more
wiley +1 more source
[Morphological characteristics and clinical significance of os subfibulare in patients with chronic ankle instability]. [PDF]
Duan X +6 more
europepmc +1 more source

