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91.
Human commensal species take advantage of anthropogenic conditions that are less likely to be challenged by the selective pressures of natural environments. Their morphological and physiological phenotypes can therefore dissociate from habitat characteristics. Understanding how these species adjust their morphological and physiological traits across latitudinal gradients is fundamental to uncovering the eco-physiological strategies underlying coping mechanisms. Here, we studied morphological traits in breeding Eurasian tree sparrows (ETSs; Passer montanus) among low-latitude (Yunnan and Hunan) and middle-latitude (Hebei) localities in China. We then compared body mass; lengths of bill, tarsometatarsus, wing, total body, and tail feather; and baseline and capture stress-induced levels of plasma corticosterone (CORT) and the metabolites including glucose (Glu), total triglyceride (TG), free fatty acid (FFA), total protein, and uric acid (UA). None of the measured morphological parameters varied with latitude except in the Hunan population, which demonstrated longer bills than those in other populations. Stress-induced CORT levels significantly exceeded baseline levels and decreased with increasing latitude, but total integrated CORT levels did not vary with latitude. Capture stress-induced significantly increased Glu levels and decreased TG levels, independent of site. However, the Hunan population had significantly higher baseline CORT, baseline and stress-induced FFA levels, but lower UA levels, which differed from other populations. Our results suggest that rather than morphological adjustments, physiological adjustments are mainly involved in coping mechanisms for middle-latitude adaptation in ETSs. It is worth investigating whether other avian species also exhibit such dissociation from external morphological designs while depending on physiological adjustments.  相似文献   
92.
为确定甘肃高寒雨养区燕麦(Avena sativa)种子生产中磷肥最佳用量,提高肥料利用效率,试验在氮肥(尿素)用量75 kg·hm-2的固定水平下,设计4个磷肥(P2O5)水平(0(CK),65(C1),100(C2),135(C3)kg·hm-2),对各磷肥水平下干草产量、种子产量和相关性状的变化进行了研究。结果表明:施用磷肥使燕麦的株高、茎粗、分蘖和干草产量均有提高,灌浆期C1,C2,C3干草产量较CK依次提高13.85%,25.96%,22.65%,干草产量与磷肥水平显著正相关(相关系数0.91);施用磷肥提高了燕麦的有效分蘖数、主穗长,显著提高主穗粒数、穗粒重、千粒重、种子产量和秸秆产量,C1,C2,C3种子产量较CK依次提高12.37%,16.72%,14.38%,种子产量与磷肥水平显著正相关...  相似文献   
93.
陆地棉品种间杂种苏杂16棉铃发育动态研究   总被引:5,自引:6,他引:5  
棉铃发育过程中,苏杂16单铃子棉主的提高表现为二个方面:一是纤维干重的增加,1991~1992两年平均增加10.0%;二是种子重量的提高,两年平均单铃种仁重增加9.4%。单铃纤维干重的增长与棉铃对位叶大小呈正相关关系,与棉铃对位叶中全N含量呈负相关关系.该杂文组合在棉铃发育过程中表现了较强的“源”“库”生理优势,光合产物积累多,营养物质运转快是该组合获得高产的重要生理基础。  相似文献   
94.
According to the character of PD in GIS, the authors design four kinds of GIS defection models. The GIS gray intensity images are constructed based on mass specimens gathered by the ultra - high frequency and high speeds systems, Aiming at the PD characteristics and its defections, A PCA-FDA method is put forward based on PD images. The principal component analysis is employed to condense the dimension of PD images, then the optimal sets of statistically uncorrelated discriminant vectors are extracted, and the minimum distance classifier is constructed as classifier. The identified results show that this method can effectively elevated the discrimination of the four kinds of defects in GIS PD.  相似文献   
95.
Basing eliminating on the idea that the generator who has the most influence on the power flow of line is mostly in favor of transmission congestion, the model of congestion management with the object of minimizing adjustments of bufions varied with generation outputs is proposed. It can eliminate the congestion effectively by judging the generators who should be adjusted and the amounts of adjustment. The test on IEEE-RTS24 buses system and other practical systems show that the proposed method is effective.  相似文献   
96.
The .experimental system of differential Isodyne developed by authors is represented. The function and structure characteristic of the rotatable real-time loading device which is set in oil tank , the hydraulic scanning device and the device for synchronous movement of incident beam and Isodyne collector are mainly discussed. The fringe pattern of differential Isodyne in various characteristic directions and planes can be real-timely taken, by using this system. This system is able to apply to stress analyses of local effect .composite materials and structures.  相似文献   
97.
The influenfial factors of stratification plane to smooth blasting are studied according to the ti eory of smooth blasting and the anslysis of static stress. The results show that the angle p between the maximum principal plane and the rertical line of stratification plane has some influence on the fracture of rock masses.  相似文献   
98.
This paper ainalyses the size effect of the fracture energy of concrete tested bythree point bending. It is shown that positive errors of test results of fracture energy increase,ornegative errors decrease with increasing of the specimen ize. The phenomenon is one of main causesresulting in the size effect of fracture energy.  相似文献   
99.
精细梁不同于Euler梁和Timoshenko梁,该模型在考虑剪切变形的同时还考虑了横向弯曲时截面转动产生的附加轴向位移及横向剪切变形影响截面抗弯刚度后产生的附加横向位移。推导了适用于向量式有限元分析的精细梁单元应变和内力表达式,采用FORTRAN自编了向量式有限元程序。对悬臂梁、两端固支梁和门式框架进行了算例分析,对比了采用不同梁单元模型下结构的竖向位移。结果表明:当高跨比较小时,3种梁单元的竖向位移相差不大;当高跨比较大时,精细梁单元的竖向位移较Euler梁和Timoshenko梁明显增大,表明剪切变形及刚度折减引起的附加轴向位移、附加横向位移不能忽略。精细梁单元模型对高跨比较大的梁进行分析可望得到更精确的结果。  相似文献   
100.
When analysing the performance of casting powders in a specific casting machine, the thickness of liquid slag is a very important parameter. If the liquid slag thickness is not kept above a certain minimum value during the continuous casting operation,the surface and internal quality of the cast products will be jeopardised because lubrication between the strand and the mould is impaired . It is necessary, therefore , to choose the appropriate type of mould powder .In the industrial experiments, it is very difficult and expensive to study this sensitivity by introducing controlled variation in one parameter while keeping all the other constant. Numerical and computer simulation methods are used in the study .They can predict the liquid slag thickness developed above the liquid steel and distribution of the temperature. The sensitivity of the liquid slag thickness to variations can be determined in the material properties of the mould powders.  相似文献   
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