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1.
Based on the analysis of the three-year (2000-2002) monitoring data of the four times intermittent stream water conveyance to the lower reaches of Tarim River where the stream flow was dried up for more than 30 years and the measurement of PRO, SOD and POD in plants collected from 24 vegetation plots, it is concluded that the stream water conveyance plays an important role in lifting groundwater level. The groundwater nearby the watercourse was raised from 5~8 m in depth before the stream water conveyance to 2.5~5 m after stream water conveyance. The physiological response of Phragmites communis, Tamarix spp. And Populus euphratica to the change of groundwater is sensitive and represents a grads change obviously. The growth of the plants in the lower reaches of Tarim River is stressed by drought to various degrees. Lengthways, the drought stress exposed to the plants increases with groundwater depth from the upper sections to the lower sections; and breadthwise, the drought stress exposed to the plants is increased with the increase of distance away from the river channel of stream intermittent water releases and of the groundwater depth. Combining the field investigation and the analysis of the plots, it is considered that the stress groundwater depths for the Phragmites communis, Tamarix spp. And Populus euphratica are 3.5 m, 5 m and 4.5 m respectively.  相似文献   

2.
The vertically dependent expressions of obliquely incident waves induced radiation stress are derived by use of the second order Stokes wave theory within three regions of the water column,that is,above the mean water level,below the wave trough level,and between these two levels.Computations indicate that the wave-induced radiation stress below the wave trough level is from the water wave particle velocity only,whereas both the water wave particle velocity and the wave pressure contribute to the tensor above the wave trough level;the vertical variations of the wave-induced radiation stress are influenced substantially by the velocity component in the direction of wave propagation;the distributions of the wave-induced radiation stress tensor over depth are non-uniform and the proportion of the tensor below the wave trough level becomes considerable in the shallow water;from water surface to seabed,the reversed variations occur for the predominant tensor components.  相似文献   

3.
4.
The 12 May 2008 Ms 8.0 Wenchuan earthquake caused notable changes in the water levels of wells in the Three Gorges area. This work examines the relationship between these coseismic changes in water level and the changes in aquifer parameters. Three wells in the area with good responses to earth tide were chosen for analysis. Water-level data from February to June 2008 were used to calculate the aquifer transmissivity, permeability and specific storage of the rocks, and analyze the relationship between the coseismic responses of the wells and their aquifer parameters. The results show that the Wenchuan earthquake changed these parameters considerably, thereby controlling co- and postseismic variations of water level. The values of these parameters prior to the earthquake are linearly related with the amplitudes of coseismic variations in water level. The larger the aquifer transmissivity, the more remarkable the coseismic change in water level. During the earthquake, changes in aquifer parameters were found to be associated with coseismic variations in water level, with the larger changes occurring when the coseismic variation in water level was larger. The tectonic setting has a certain degree of influence on the co- and postseismic changes in water level. The permeability structures of the fault zone appear to determine the manner of coseismic variation in water level. Moreover, it seems that the water level in wells where groundwater converges more easily can recover faster following an earthquake. Insight from this study helps to improve understanding of the characteristics of water-level changes caused by earthquakes.  相似文献   

5.
Based on immune network regulatory mechanism, a new adaptive immune evolutionary algorithm (AIEA) is proposed to improve the performance of genetic algorithms (GA) in this paper. AIEA adopts novel selection operation according to the stimulation level of each antibody. A memory base for good antibodies is devised simultaneously to raise the convergent rapidity of the algorithm and adaptive adjusting strategy of antibody population is used for preventing the loss of the population adversity. The experiments show AIEA has better convergence performance than standard genetic algorithm and is capable of maintaining the adversity of the population and solving function optimization problems in an efficient and reliable way.  相似文献   

6.
Mercury(II) is an important factor in hepatotoxicity that can enter the body through marine diets and amalgams.In the present study,the protective effect of the Eriobotrya japonica flower extract(EJFE) on HgCl 2-induced hepatotoxicity was investigated.Five mg/kg of mercuric chloride in drinking water was given to rats either with saline or EJFE(100 and 200 mg/kg as intraperitoneal(IP)) for 30 d.The mercury levels in different groups of liver tissues of the rats were measured with flameless atomic absorption spectroscopy(F-AAS).Also,mercury accumulation in the liver of the rats was modeled by using a parallel chemical kinetic model.The results showed that HgCl 2-induced oxidative damage led to a significant decrease in glutathione(GSH) and the total antioxidant capacity(TAC) levels,and to a significant increase in lipid peroxidation level.Accumulated mercury was 14.47% more in the livers of the stress groups than in those of the control groups(P<0.001),whereas the amount of Hg was adjusted to 13.49% and 13.93% in groups treated with 100 and 200 mg/kg of EJFE respectively,as compared with stress groups(P<0.001).HPLC analysis of EJFE revealed that hesperetin and gallic acid are the major antioxidants in EJFE.Results demonstrate that flowers of the Eriobotrya japonica cause a significant protection against HgCl 2 induced hepatotoxicity in all diagnostic parameters by strengthening the antioxidant defense mechanisms and they may have a therapeutic function in free radical mediated diseases.  相似文献   

7.
Seepage properties of a single rock fracture subjected to triaxial stresses   总被引:1,自引:0,他引:1  
Coupled properties of seepage and stress fields of rock fractures greatly influence the safety of geotechnical engineering work. Based on the closing deformation principle of a single rock fracture, equations describing relationships of aperture and triaxial stresses are developed, and coupled models of seepage and triaxial stresses are proposed. Seepage tests are conducted under triaxial stress conditions by adopting hard granite specimens with an artificial fracture. The results show that the normal stress, lateral stress and seepage pressure significantly affect the flow behavior of rock fractures, and that hydraulic conductivity decreases with increasing normal stress, but increases with rising lateral stress or seepage pressure. In addition, an exponential function provides a good representation of the seepage characteristics of a single rock fracture subjected to triaxial stresses.  相似文献   

8.
The signaling pathway for tumor necrosis factor-a (TNF-a) and its receptors is up-regulated during ex- tracorporeal circulation (ECC), and recruits blood neutrophil into the lung tissue, which results in acute lung injury (ALl) In this study, we evaluated the role of tumor necrosis factor receptor I (TNFR1) in ECC-induced ALl by blocking TNF-a binding to TNFR1 with CAY10500. Anesthetized Sprague-Dawley (SD) rats were pretreated intravenously with phos- phate buffered saline (PBS) or vehicle (0.3 ml ethanol IV) or CAY10500, and then underwent ECC for 2 h. The oxy- genation index (OI) and pulmonary inflammation were assessed after ECC. OI was significantly decreased, while TNF-a and neutrophil in bronchoalveolar lavage fluid (BALF) and plasma TNF-a increased after ECC. Pretreatment of CAY10500 decreased plasma TNF-a level, but did not decrease TNF-a levels and neutrophil counts in BALF or improve OI. Lung histopathology showed significant alveolar congestion, infiltration of the leukocytes in the airspace, and increased thickness of the alveolar wall in all ECC-treated groups. CAY10500 pretreatment slightly reduced leukocyte infiltration in lungs, but did not change the wet/dry ratio in the lung tissue. Blocking TNF-a binding to TNFR1 by CAY10500 intravenously slightly mitigates pulmonary inflammation, but cannot improve the pulmonary function, indicating the limited role of TNFR1 pathway in circulating inflammatory cell in ECC-induced ALl.  相似文献   

9.
The soil water retention curve is an important hydraulic function for the study of flow transport processes in unsaturated soils. The objective of this study was to develop a soil water retention function using a generalized fractal approach. The model exhibits asymmetry between the solid phase and pore phase, which is in marked contrast to the symmetry between phases present in a conventional fractal model. The retention function includes 4 parameters: the saturated water content θs, the air entry value ha, the fractal dimension Df, and an empirical parameter β, characterizing the complicated soil pore structures. Sixty one data sets, covering a wide range of soil structure and textural properties, were used to evaluate the applicability of the proposed soil water retention function. The retention function is shown to be a general model, which incorporates several existing retention models. The values of β/θs and (θs-θr )/β were used as indexes to quantify the relationships between the proposed retention function and the existing retention models. The proposed function fits all the data very well, whereas other tested models only match about 16%-48% of the soil retention data.  相似文献   

10.
A numerical study of stress distribution and fatigue behavior in terms of the effect of voids adjacent to inclusions was conducted with finite element modeling simulations under different assumptions.Fatigue mechanisms were also analyzed accordingly.The results showed that the effects of inclusions on fatigue life will distinctly decrease if the mechanical properties are close to those of the steel matrix.For the inclusions,which are tightly bonded with the steel matrix,when the Young’s modulus is larger than that of the steel matrix,the stress will concentrate inside the inclusion;otherwise,the stress will concentrate in the steel matrix.If voids exist on the interface between inclusions and the steel matrix,their effects on the fatigue process differ with their positions relative to the inclusions.The void on one side of an inclusion perpendicular to the fatigue loading direction will aggravate the effect of inclusions on fatigue behavior and lead to a sharp stress concentration.The void on the top of inclusion along the fatigue loading direction will accelerate the debonding between the inclusion and steel matrix.  相似文献   

11.
应激的可预期性和行为控制对大鼠免疫功能的影响   总被引:3,自引:0,他引:3  
研究了电击的可预期性和行为控制对大鼠免疫功能的影响以及糖皮质激素可能的中介作用。实验结果表明,给予大鼠不可躲避的足底电击,经过两次实验,脾淋巴细胞的转化受到抑制,cpm值降低1/3。如果每次电击前给予一个警告信号,由于可预期的事件产生的心理压力比不可预期事件小,结果脾淋巴细胞的转化受到的抑制不明显。  相似文献   

12.
目的:分析针刺对焦虑障碍大鼠肾上腺心房利钠肽、C型利钠肽水平和血浆皮质酮含量的影响,探讨针刺治疗焦虑障碍的部分机制.方法选取SPF级SD大鼠随机分为空白对照组、模型组、针刺组.模型组、针刺组大鼠建立慢性情绪应激刺激焦虑模型,针刺组同时针刺“内关”、“神门”,每2 d针刺1次,45 min/次,共15 d.空白对照组和模型组用相同方法固定,不做任何干预.使用高架十字迷宫观察大鼠行为学变化,计算进入开臂次数( OE)和停留时间( OT)分别占进入总次数和停留时间的百分比;ELISA法检测大鼠血浆皮质酮水平;免疫组化S-P法检测大鼠肾上腺心房利钠肽、C型利钠肽水平.结果针刺组大鼠OT值明显高于模型组,差异具有统计学意义(P<0.05),与空白对照组之间差异无统计学意义(P>0.05);3组大鼠OE值之间差异均无统计学意义(P>0.05).模型组大鼠浆皮质酮含量明显高于空白对照组,差异具有统计学意义(P<0.05);针刺组大鼠浆皮质酮含量明显低于模型组,差异具有统计学意义(P<0.05);针刺组与空白对照组之间差异无统计学意义(P>0.05).模型组大鼠肾上腺皮质和髓质中的心房利钠肽水平均低于空白对照组,C型利钠肽水平均高于空白对照组,差异具有统计学意义(P<0.05);针刺组大鼠肾上腺皮髓质心房利钠肽明显高于模型组,C型利钠肽明显低于模型组,差异具有统计学意义(P<0.05);针刺组肾上腺髓质心房利钠肽、C型利钠肽与模型组之间差异无统计学意义(P>0.05).结论针刺可通过调节外周肾上腺髓质心房利钠肽、C型利钠肽水平,进而影响血浆皮质酮释放,抑制HPA轴活性,发挥抗焦虑作用.  相似文献   

13.
大鼠固定(每天2.5h)连续7天,用放免法分别测得固定前1天及固定1、3、5、7天血浆皮质酮含量。结果发现,随着固定的持续,血浆皮质酮的含量逐渐升高,固定第3天即达高峰60.4±5.0μg/dl(P<0.01)以后有所下降,固定第5天为56±3.4μg/dl(P<0.01),第7天为47.3±2.5μg/dl(P<0.01)。而对照组在相同期间皮质酮含量前后对比无显著性差异。这一结果表明,在固定应激过程中,下丘脑—垂体—肾上腺皮质系统起了一定的作用。  相似文献   

14.
Studies on social isolation have provided evidence for an enhanced anxiety-like phenotype, depressive-like symptoms and higher levels of 22-kHz ultrasonic vocalizations (USVs); whereas sexual experience could induce significant changes in affective states, decrease anxiety- and depressive-like responses. However, the behavioral and emotional alterations in male rats exposed to isolation after sexual experience remain poorly understood. Therefore, the present study examined anxiety- and depressive-like parameters, as well as USV emissions in male rats isolated for 1, 2, or 7 d following 1-week sexual (male-female paired housing) or social (male-male paired housing) interaction. Isolation for 1 d resulted in increased depressive-like symptoms, and 2-d isolation induced elevated anxiety-like behavior in sexually inexperienced rats, while rats with sexual experience exhibited comparable levels of emotionality at each isolation time. Moreover, isolated rats without sexual experience emitted less 22- and 50-kHz USVs, but sexually experienced rats exhibited similar affective states compared with control ones. These results suggested that prior sexual experience could have a modulatory effect on experimental rat emotional responses to isolation.  相似文献   

15.
心理应激不但严重威胁人体健康,其产生的应激情绪反应导致的应激情绪行为反应也严重影响着运动的发展。针对心理应激产生的心理类型,建立相应的心理应激情绪反应动物运动模型。研究心理应激产生的机制和发生过程,采取相应的有效手段,克服与治疗心理应激情绪反应对应激情绪运动行为的负面影响,有助于提高运动水平。  相似文献   

16.
探讨束缚浸水应激对大鼠外周血白细胞数量的影响.采用大鼠束缚浸水应激模型,观察大鼠束缚浸水、切断迷走神经、阿托品和酚妥拉明对白细胞数量的影响.与正常对照组相比,束缚浸水应激组白细胞、中性粒细胞以及淋巴细胞的数目显著减少(P〈0.05);与不切断迷走神经相比,切断迷走神经组中自细胞和嗜酸性粒细胞的数目显著降低(P〈0.05),中性粒细胞与单核细胞数目非常显著减少(P〈0.01);与束缚浸水应激相比,注射阿托品组中,各免疫细胞数目无明显差异;注射酚妥拉明大鼠淋巴细胞显著减少(P〈0.05),白细胞数量虽然升高,但不明显.束缚浸水应激能显著降低外周血的白细胞、中性粒细胞及淋巴细胞的数目,迷走神经和交感神经参与了束缚浸水应激过程,且可能影响免疫细胞的数目  相似文献   

17.
通过研究碱性钙离子水对大鼠血液pH、血钙浓度及免疫功能的影响,结果显示,碱性钙离子水对大鼠血液pH和血钙浓度无明显影响,对大鼠免疫功能具明显增强.100°碱性钙离子水的功效优于25°碱性钙离子水.  相似文献   

18.
目的 观察制动致福利受损SD大鼠部分行为学改变以及体内NF-κB的变化。方法 选取体质量约200 g的雄性SD大鼠,使用管状容器给予束缚应激刺激,并通过旷场实验和O迷宫观测大鼠在第0、1、3、7、10、14天的行为学表现。测定了相应时期的NF-κB p65 mRNA转录水平和蛋白表达量。结果 束缚第3天起,大鼠肝脏组织NF-κB p65 mRNA转录水平和蛋白表达均较束缚前显著增高 (P< 0.05),但此时尚未见行为学改变;束缚第7天起大鼠的活动兴趣与活动能力水平较束缚前显著下降 (P< 0.05),显示焦虑、恐惧状态。结论 制动致福利受损大鼠肝细胞内NF-κB mRNA及蛋白表达的变化早于行为学的改变。  相似文献   

19.
为了解不同剂量局部照射对大鼠睾丸重量、超微结构及性激素、白细胞的影响,对大鼠不同剂量局部照射后,睾丸组织称重,超微结构观察,测定血清睾酮、促卵泡激素水平,白细胞计数。结果表明,睾丸组织重量随照射剂量增中及时间延长。逐渐减轻,并与照射剂量及时间呈正相关;但当照剂量增加,照射时间延长至一定程度后,睾丸重量基本不变,出现相 期,超微结构观察可见生精细胞变性、坏死、随时间延长呈不可逆性变化,间质细胞形态结  相似文献   

20.
医药空瓶在生产过程中瓶身表面会产生大量的气泡缺陷,但现有的方法对医药空瓶表面气泡检测存在各种问题,例如对复杂场景变化的鲁棒性不强,抗噪声干扰能力弱等.针对现有医药空瓶表面的气泡缺陷,提出了一种改进的深度学习目标检测算法RetinaNet对瓶身气泡进行检测.对原始RetinaNet算法中的特征金字塔网络结构进行了优化,在特征融合过程中引入了特征增强模块,用来提高网路对图像语义特征的提取,增强网络特征提取能力.为了减少模型的参数数目和计算时间,考虑到空瓶表面气泡均为小目标缺陷,去掉原始特征金字塔网络中用于检测大目标的网络结构,提高了算法检测速度.通过对标准的ResNet50网络进行重新组合,并引进了膨胀卷积模块,扩大特征图感受野,提高了模型检测的精度.通过在注塑空瓶数据集上对本文的方法进行了验证,其准确率为99.72%,漏检率为0.12%,误检率为016%,mAP为99.49%,相比原始的RetinaNet的mAP提高了接近2.4%.  相似文献   

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