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51.
Bruce L. Wilson Glenn L. Albright Ph.D. Solomon S. Steiner John L. Andreassi 《Applied psychophysiology and biofeedback》1991,16(1):45-53
In the present study 36 police officers were exposed to a psychological stressor (IQ quiz) and to cold pressor stress while several cardiovascular variables were monitored. Impedance cardiography was used to provide measures of heart rate, stroke volume, cardiac output, myocardial contractility, and total peripheral resistance. In addition, measures of systolic and diastolic blood pressure and peripheral skin temperature were obtained. A multivariate analysis of variance (MANOVA) indicated that significant increases in diastolic and systolic blood pressure during the cold pressor test were mediated by large increases in total peripheral resistance, whereas blood pressure elevation during the IQ quiz were accompanied by significant increases in heart rate and, to a lesser extent, cardiac output. Peripheral skin temperature decreased in response to each stressor. Additional analysis indicated a degree of stimulus specificity for several variables. For example, diastolic blood pressure showed greater increases to cold pressor than quiz, whereas systolic blood pressure increased more with the psychological than the physical stressor. Directional fractionation occurred for both myocardial contractility and cardiac output. 相似文献
52.
Kosteletzkya virginica (K. virginica) is used for revegetation of salt-affected coastal tidal flats and as a raw material
of biodiesel. K. virginica root tuber, a biowaste with low economic value, is rich in bioactive compounds. This
study aimed to extract and identify flavonoids from K. virginica root tubers. The optimal extraction conditions
were 1/25 (w/v) solid/liquid ratio, 40% ethanol concentration at 40°C for 60 min. Under these conditions,
65.2 ± 3.7 mg/g total flavonoid content was extracted from the roots, which were collected from salinized soil
in late autumn of the third year. Antioxidant activity was evaluated through 1,1-diphenyl-2-picrylhydrazyl,
hydroxyl radical, and superoxide anion scavenging assays. The extracted flavonoids exhibited antioxidant activity
in a dose-dependent manner. Five flavonoids, glucoliquiritin apioside, licoisoflavone B, 5-methoxy-7,8-diprenyl-
flavone, 7,2′-dihydroxy-6,8-dimethyl-4′,5′-methylenedioxyflavan, and 5,7,4′-trihydroxy-3′-methoxy-6,8-di-Cmethylflavanone, were identified by ultra-performance liquid chromatography–tandem mass spectrometry.
Our results suggest that the flavonoids of K. virginica root tubers might be potent antioxidants and can be effectively applied as an ingredient in food and natural medicine. 相似文献
53.
黄土丘陵区小流域土地利用对土壤有机碳和全氮的影响 总被引:14,自引:0,他引:14
通过野外调查和室内分析,研究了黄土丘陵沟壑区燕沟流域农地、果园、林地和草地0~20cm表层土壤的有机碳(SOC)和全氮(TSN)积累特征.结果表明:该区SOC含量平均值为7·56g·kg-1,TSN平均值为0·71g·kg-1.其中,农地SOC和TSN平均值分别为4·67和0·48g·kg-1,且梯田较低,川坝地较高.与农地相比,果园SOC(4·33g·kg-1)和TSN(0·46g·kg-1)平均值略有降低,草地较高.林地SOC和TSN平均值较农地高117·7%和89·4%.该区SOC和TSN含量的变异系数为69·7%和58·4%,以林地最大(62·8%和54·5%),草地和农地次之,果园最小(18·0%和22·9%).土壤C/N依果园、农地、草地和林地的顺序递增.该区各类土地利用方式下的SOC和TSN都呈极显著正相关(r=0·9791).黄土丘陵沟壑区基本农田建设和果园建设对SOC和TSN积累作用不明显;退耕还林还草、封山育林等土地利用优化措施明显促进了SOC和TSN的积累. 相似文献
54.
55.
Zhanjia Hou 《Journal of molecular biology》2010,402(1):210-35050
To investigate the regulation of SERCA1a [sarco(endo)plasmic reticulum calcium ATPase] and SERCA2a calcium pump isoforms by phospholamban (PLB), we quantified PLB-SERCA interactions by fluorescence resonance energy transfer (FRET) in live cells. For both SERCA1a and SERCA2a, FRET to PLB increased with increasing protein expression level to a maximum value corresponding to a probe separation distance of 64 Å. The data indicate that the respective regulatory complexes assume the same overall quaternary conformation. However, FRET measurements also revealed that PLB has a 50% higher apparent affinity for SERCA1a relative to SERCA2a. The results suggest that despite the structural similarities of the respective regulatory complexes, there is preferential binding of PLB to SERCA1a over SERCA2a. This apparent selectivity may have implications for biochemical studies in which SERCA1a is used as a substitute for SERCA2a. It may also be an important strategic consideration for therapeutic overexpression of SERCA isoforms in cardiac muscle. 相似文献
56.
57.
以湘江熬洲断面为例,将该断面水体中总氮浓度及其有关影响因子用三角模糊数来表征.同时,结合己有的模糊线性回归模型成果,构造了带有三角模糊参数的水体中总氮浓度模糊线性回归预测模型.并应用所建模型预测该断面水体中2002-2005年总氮浓度,所得的预测值与已有的实测值之间的相对误差均小于20%,完全满足实际应用对误差的要求,预测合格率为100%,说明这种预测模型在预测河流水体总氮浓度变化中有一定的实用性,为今后开展河流水体中污染物浓度预测提供了新途径. 相似文献
58.
H. Llaneza Coalla J.M. Blanco FernándezM.A. Morís Morán M.R. López Bobo 《Bioresource technology》2009,100(17):3843-3847
In view of the pressing problem that appears in our region (Asturias, north of Spain) with the residues from the cider production, it was decided to test this kind of material as a co-substrate joint with slaughterhouse waste in a laboratory unit. 相似文献
59.
The structure of the lipopolysaccharide core of Vibrio vulnificus type strain 27562 is presented. LPS hydrolysis gave two oligosaccharides, OS-1 and OS-2, as well as lipid A. NMR spectroscopic data corresponded to the presence of one Kdo residue, one β-glucopyranose, three heptoses, one glyceric acid, one acetate, three PEtN, and one 5,7-diacylamido-3,5,7,9-tetradeoxynonulosonic acid residue (pseudaminic acid, Pse) in OS1. OS2 differed form OS 1 by the absence of glyceric acid, acetate, and Pse residues. Lipid A was analyzed for fatty acid composition and the following fatty acids were found: C14:0, C12:0-3OH, C16:0, C16:1, C14:0-3OH, C18:0, C18:1 in a ratio of 1:3:3:1:2.5:0.6:0.8. 相似文献
60.
V. V. Maksimov E. V. Shchetinina O. V. Kraykivskaya E. A. Maksimova 《Microbiology》2006,75(6):653-657
The survival rate, metabolic activity, and ability for growth of microbial communities of Lake Baikal have been first studied after exposure to extremely low temperatures (freeze-thawing) for different lengths of time. It has been shown that short-term freezing (1–3 days) inhibits the growth and activity of microbial communities. The quantity of microorganisms increased after 7-and 15-day freezing. In the periods of maximums, the total number of microorganisms in the test samples was twice as high as in the control. It was established that after more prolonged freezing the microorganisms required more time after thawing to adapt to new conditions. In the variants with 7-and 15-day freezing, the activities of defrosted microbial communities were three or more times higher than in the control. The survival rate and activity of Baikal microorganisms after freeze-thawing confirms the fact that the Baikal microbial communities are highly resistant to this type of stress impact. 相似文献