期刊文献+
共找到2,133篇文章
< 1 2 107 >
每页显示 20 50 100
The Wingate anaerobic test cannot be used for the evaluation of growth hormone secretion in children with short stature 被引量:1
1
作者 Nitzan Dror Liat Oren +2 位作者 Michal Pantanowitz Alon Eliakim Dan Nemet 《Journal of Sport and Health Science》 SCIE 2017年第4期443-446,共4页
Purpose: To assess the growth hormone(GH) response to the Wingate anaerobic test(WAn T) among children with short stature and suspected GH deficiency. We hypothesized that the GH response to the WAn T would be similar... Purpose: To assess the growth hormone(GH) response to the Wingate anaerobic test(WAn T) among children with short stature and suspected GH deficiency. We hypothesized that the GH response to the WAn T would be similar to the GH response to a commonly used pharmacologic provocation test.Methods: Ten children(6 males and 4 females, age range 9.0–14.9 years) participated in the study. Each participant performed 2 tests: a standard all-out WAn T, cycling for 30 s against constant resistance, and a standardized pharmacologic test(clonidine or glucagon). Blood samples for GH were collected before and 10, 30, 45, and 60 min after the beginning of exercise. In addition, we collected pre-and post-exercise blood lactate levels.Results: There was a significant increase in GH levels after the WAn T, yet in 9 of 10 participants, this increase was below the threshold for GH sufficiency. Peak GH after the WAn T was significantly lower compared to the pharmacologic GH provocation tests(with 9 of 10 demonstrating GH-sufficient response).Conclusion: The traditional WAn T cannot be used as a GH provocation test. Further research is needed to develop anaerobic exercise protocols sufficient to promote GH secretion. 展开更多
关键词 ANAEROBIC EXERCISE growth hormone LACTATE Provocation test Short stature
下载PDF
Bayesian sequential testing for exponential life system with reliability growth 被引量:4
2
作者 Yunyan Xing Xiaoyue Wu 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2011年第6期1023-1029,共7页
A Bayesian sequential testing method is proposed to evaluate system reliability index with reliability growth during development.The method develops a reliability growth model of repairable systems for failure censore... A Bayesian sequential testing method is proposed to evaluate system reliability index with reliability growth during development.The method develops a reliability growth model of repairable systems for failure censored test,and figures out the approach to determine the prior distribution of the system failure rate by applying the reliability growth model to incorporate the multistage test data collected from system development.Furthermore,the procedure for the Bayesian sequential testing is derived for the failure rate of the exponential life system,which enables the decision to terminate or continue development test.Finally,a numerical example is given to illustrate the efficiency of the proposed model and procedure. 展开更多
关键词 reliability growth Bayesian method prior distribution sequential testing exponential life system.
下载PDF
The Relationship between Energy Consumption and Economic Growth in the USA: A Non-Linear ARDL Bounds Test Approach 被引量:1
3
作者 Arzu Tay Bayramoglu Ertugrul Yildirim 《Energy and Power Engineering》 2017年第3期170-186,共17页
We study the relationship between energy consumption and economic growth in the case of USA by using an asymmetric ARDL bounds test approach to achieve the actual model. The quarterly data set covers the period of 197... We study the relationship between energy consumption and economic growth in the case of USA by using an asymmetric ARDL bounds test approach to achieve the actual model. The quarterly data set covers the period of 1973:1- 2013:4. The findings indicate that the effect of energy consumption is asymmetric in the long term but not in the short term. In the long run, the effect of negative component of energy consumption on economic growth is small and statistically insignificant. The coefficient of the positive component of energy consumption is found about 0.9 and statistically significant at 1% level. We conclude that energy saving policies such as technological progress and organizational rearrangements may have the dimmer effect for the impact of a negative component of energy consumption and the booster effect for impact of the positive component of energy consumption. Thus, energy saving policy should be tightly followed by the goal of high economic growth. 展开更多
关键词 Energy CONSUMPTION Economic growth NON-LINEAR ARDL BOUNDS test USA
下载PDF
lower Oil Prices Test Africa’s growth
4
作者 Hannah Edinger Kira McDonald 《ChinAfrica》 2015年第1期10-11,共2页
The foundations of the "Africa rising" narrative may have increasingly been tested in recent months. Security concerns, the Ebola crisis in West Africa and conflict in Libya have been some of the stumbling blocks th... The foundations of the "Africa rising" narrative may have increasingly been tested in recent months. Security concerns, the Ebola crisis in West Africa and conflict in Libya have been some of the stumbling blocks the continent has had to face. These have continuously challenged its ability to respond to events that could derail the past years' economic growth. The impact of lower oil prices particularly could be a major shock to the region, especially for oilexporting countries. 展开更多
关键词 lower Oil Prices test Africa’s growth
下载PDF
Relationship between Growth Hormone and Cytokines in Short Children Undergoing Growth Hormone Stimulation Testing
5
作者 Kimberly Tafuri Denise Dixon +2 位作者 Katherine Markarian Andrew Lane Thomas A. Wilson 《International Journal of Clinical Medicine》 2015年第12期912-918,共7页
Background: The relationship between growth hormone (GH) and cytokines remains unclear. Several studies have suggested that GH increases tumor necrosis factor (TNF)-α production in both children and adults. However, ... Background: The relationship between growth hormone (GH) and cytokines remains unclear. Several studies have suggested that GH increases tumor necrosis factor (TNF)-α production in both children and adults. However, a number of studies have demonstrated a negative correlation between GH and TNF α. The aim of this study is to explore the relationship between endogenous GH secretion and certain pro and anti-inflammatory cytokines in short children undergoing GH stimulation testing for evaluation for GH deficiency. Methods: Plasma growth hormone, TNF α, CRP, IL-6, IL1-β, IL-4 and IL-10 levels are obtained at baseline and every 30 minutes for 150 minutes following two provocative agents (clonidine, and either arginine or glucagon). Results: Among the 23 children, 7 are found to be GH deficient. No significant differences in baseline TNF α levels are found between GH deficient and GH sufficient children. No correlation is identified between TNF α levels and GH levels during stimulation testing. Furthermore, no relationship is found between GH and pro-inflammatory cytokines or GH and anti-inflammatory cytokines. Conclusion: Our results do not demonstrate an acute relationship between endogenous GH secretion and the cytokines examined. 展开更多
关键词 growth HORMONE Tumor Necrosis Factor-α CYTOKINES CRP IL-6 IL1-β IL-4 IL-10 growth HORMONE STIMULATION testING CLONIDINE Arginine Glucagon
下载PDF
Effects of Sodium Chloride Stress on Growth of Sweet Potato Plantlets in vitro and Ion Content 被引量:13
6
作者 高叶 赵术珍 +2 位作者 陈敏 宋晓征 王宝山 《Agricultural Science & Technology》 CAS 2008年第5期27-30,共4页
[Objective] This study aimed to investigate the salt-tolerance mechanism of sweet potato.[Method]Two sweet potato varieties of Xu 25-2(salt-tolerant cultivar)and Triumph 100(salt-sensitive cultivar)were treated by sod... [Objective] This study aimed to investigate the salt-tolerance mechanism of sweet potato.[Method]Two sweet potato varieties of Xu 25-2(salt-tolerant cultivar)and Triumph 100(salt-sensitive cultivar)were treated by sodium chloride with the concentration of 0 mmol/L and 100 mmol/L.After 20 days,Na+ content and Na+/K+ ratio in the roots,shoots and leave were determined by the flame photometer,while dry weight and fresh weight of roots,shoots and leave in different varieties were also studied.[Result]The growth of two sweet potato varieties was inhibited under salt stress,so the plant became shorter,leaf and root became fewer,dry weight of roots and leave decreased,but seedlings of Xu 25-2 were inhibited slightly.Furthermore,Na+ content and Na+/K+ ratio in roots,shoots and leaves of two sweet potato varieties increased.Na+ content of salt-tolerant Xu 25-2 was low in roots,shoots and leaves,while Na+ content of salt-sensitive Triumph 100 was high in shoots and leave of seedlings,but the change range of Xu 25-2 was less than that of Triumph 100.[Conclusion]The lower Na+ content and Na+/K+ ratio in leaves under salt stress were the most important characteristics for salt-tolerance of sweet potato varieties. 展开更多
关键词 SALT STRESS Sweet potato test-tube PLANTLET growth Ion content SALT tolerance
下载PDF
HER2 testing in gastric cancer: An update 被引量:22
7
作者 Lucas Faria Abrahao-Machado Cristovam Scapulatempo-Neto 《World Journal of Gastroenterology》 SCIE CAS 2016年第19期4619-4625,共7页
Human epidermal growth factor receptor 2(HER2) overexpression is increasingly recognized as a frequent molecular abnormality in gastric and gastroesophageal cancer. With the recent introduction of HER2 molecular targe... Human epidermal growth factor receptor 2(HER2) overexpression is increasingly recognized as a frequent molecular abnormality in gastric and gastroesophageal cancer. With the recent introduction of HER2 molecular targeted therapy for patients with advanced gastric cancer, determination of HER2 status is crucial in order to select patients who may benefit from this treatment. This paper provides an update on our knowledge of HER2 in gastric and gastroesophageal cancer, including the prognostic relevance of HER2, the key differences between HER2 protein expression interpretation in breast and gastric cancer, the detection methods and the immunohistochemistry scoring system. 展开更多
关键词 Human epidermal growth factor receptor 2 testing Gastric cancer IMMUNOHISTOCHEMISTRY Scoring system TRASTUZUMAB
下载PDF
Evaluating the quality of feed fats and oils and their effects on pig growth performance 被引量:3
8
作者 Gerald C Shurson Brian J Kerr Andrea R Hanson 《Journal of Animal Science and Biotechnology》 SCIE CAS CSCD 2016年第3期330-340,共11页
Feed fats and oils provide significant amounts of energy to swine diets, but there is large variation in composition,quality, feeding value, and price among sources. Common measures of lipid quality include moisture, ... Feed fats and oils provide significant amounts of energy to swine diets, but there is large variation in composition,quality, feeding value, and price among sources. Common measures of lipid quality include moisture, insolubles,and unsaponifiables(MIU), titer, and free fatty acid content, but provide limited information regarding their feeding value. Lipid peroxidation is an important quality factor related to animal growth performance and health, but maximum tolerable limits in various lipids have not been established. Several indicative assays can be used to detect the presence of various peroxidation compounds, but due to the complexity and numerous compounds produced and degraded during peroxidation process, no single method can adequately determine the extent of peroxidation. Until further information is available, using a combination of peroxide value, thiobarbituric acid reactive substances(TBARS), and anisidine value appear to provide a reasonable assessment of the extent of peroxidation in a lipid at a reasonable cost. However, fatty acid composition of the lipid being evaluated should be considered when selecting specific assays. Predictive tests can also be used to estimate the stability or susceptibility of lipids to peroxidation and include active oxygen method, oil stability index, and oxygen bomb method. A review of 16 published studies with pigs has shown an average decrease of 11.4% in growth rate, 8.8% feed intake fed isocaloric diets containing peroxidized lipids compared to diets containing unperoxidized lipids of the same source.Furthermore, serum vitamin E content was generally reduced and serum TBARS content was increased when peroxidized lipids were fed in these studies, suggesting that feeding peroxidized lipids negatively affects metabolic oxidative status of pigs. However, it is unclear if antioxidants are useful additions to lipids to maintain optimal nutritional value, or if their addition to swine diets is beneficial in overcoming a metabolic oxidative challenge. 展开更多
关键词 growth Indicative tests Lipids Metabolic oxidation Peroxidation Pigs
下载PDF
STUDIES ON CULTURE CONDITIONS OF BENTHIC DIATOMS FOR FEEDING ABALONE Ⅲ. EFFECTS OF IRON AND SILICON NUTRIENTS AND OF ORTHOGONAL COMBINATIONS OF NITROGEN,PHOSPHORUS,IRON AND SILICON ON GROWTH RATE 被引量:5
9
作者 王起华 李雅娟 李梅 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 1999年第2期105-111,共7页
Effects of iron and silicon nutrients and of orthogonal combinations of nitrogen, phosphorus, iron and silicon on the growth rate of three benthic diatoms were studied by using an in situ OD measurement method. The re... Effects of iron and silicon nutrients and of orthogonal combinations of nitrogen, phosphorus, iron and silicon on the growth rate of three benthic diatoms were studied by using an in situ OD measurement method. The results of monofactor tests of ironand silicon shawed that Fe-EDTA was bettef than ferric citrate in the culture of these diatoms;that the favourable concentration of Fe-EDTA was about 0.5 mg/L of Fe and that of silicate was 2.5 mg/L of Si or more.The orthogonal test showed that the optimal concentration ratios(mg/L)of nitrogen, phosphorus, iron and silicon were: 5. 0: 0. 25: 0.5: 2. 0 for Cocconeis scutellum var. parva; 2.5: 1.0: 1.0: 2.0 for Amphora coffeaeformis; and 5.0: 0. 15: 0.5: 2.0 for N. mollis. 展开更多
关键词 benthic DIATOMS NUTRIENTS ORTHOGONAL test growth rate
下载PDF
NHPP-based software reliability model considering testing effort and multivariate fault detection rate 被引量:4
10
作者 Jie Zhang Yang Lu +1 位作者 Shu Yang Chong Xu 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2016年第1期260-270,共11页
In recent decades,many software reliability growth models(SRGMs) have been proposed for the engineers and testers in measuring the software reliability precisely.Most of them is established based on the non-homogene... In recent decades,many software reliability growth models(SRGMs) have been proposed for the engineers and testers in measuring the software reliability precisely.Most of them is established based on the non-homogeneous Poisson process(NHPP),and it is proved that the prediction accuracy of such models could be improved by adding the describing of characterization of testing effort.However,some research work indicates that the fault detection rate(FDR) is another key factor affects final software quality.Most early NHPPbased models deal with the FDR as constant or piecewise function,which does not fit the different testing stages well.Thus,this paper first incorporates a multivariate function of FDR,which is bathtub-shaped,into the NHPP-based SRGMs considering testing effort in order to further improve performance.A new model framework is proposed,and a stepwise method is used to apply the framework with real data sets to find the optimal model.Experimental studies show that the obtained new model can provide better performance of fitting and prediction compared with other traditional SRGMs. 展开更多
关键词 software reliability software reliability growth mo del(SRGM) testing effort fault detection rate(FDR).
下载PDF
Cointegration Analysis on the Relation between Urbanization and Economic Growth in China 被引量:4
11
作者 LIU Ai-ying1,YAO Li-fen2,LI Qing-chen3 1.School of Business Administration,Hebei University of Economics & Business,Shijiazhuang 050061,China 2.School of Tourism,Hebei University of Economics & Business,Shijiazhuang 050061,China 3.Institute of Geographical Sciences,Hebei Academy of Science,Shijiazhuang 050011,China 《Asian Agricultural Research》 2011年第3期133-136,共4页
This paper utilizes cointegration theory,error correcting model and Granger causality testing theory to make an empirical research on the relation between urbanization and GDP in China,and also implements a comparativ... This paper utilizes cointegration theory,error correcting model and Granger causality testing theory to make an empirical research on the relation between urbanization and GDP in China,and also implements a comparative analysis to the relation between three industries and degree of urbanization,the related coeffecient is 0.97,0.95,0.97,0.97.And the result shows a long-term balance between these two factors,and the promoting effect to tertiary industry by urbanization is more obvious.Urbanization and economic growth are the long-term balanced relations.In the long-term balance,every 1% increment of urbanization can make 4.82% increment of GDP;In short-term balance,if the balance depart from the long-term balance at the i-th term,the model will take automatic reversal adjustment with-0.06 adjusting strength at the(i+1)th term,to make it move to the long-term balance.The economic growth onto urbanization is one-way causality relationship,the primary and secondary industry onto urbanization is also one-way causality relationship.However,the tertiary industry onto urbanization is both-way causality relationship. 展开更多
关键词 ECONOMIC growth URBANIZATION COINTEGRATION test ER
下载PDF
Bayesian synthetic evaluation of multistage reliability growth with instant and delayed fix modes 被引量:5
12
作者 Yan Zhiqiang Li Xinxin Xie Hongwei Jiang Yingjie 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2008年第6期1287-1294,共8页
In the multistage reliability growth tests with instant and delayed fix modes, the failure data can be assumed to follow Weibull processes with different parameters at different stages. For the Weibull process within ... In the multistage reliability growth tests with instant and delayed fix modes, the failure data can be assumed to follow Weibull processes with different parameters at different stages. For the Weibull process within a stage, by the proper selection of prior distribution form and the parameters, a concise posterior distribution form is obtained, thus simplifying the Bayesian analysis. In the multistage tests, the improvement factor is used to convert the posterior of one stage to the prior of the subsequent stage. The conversion criterion is carefully analyzed to determine the distribution parameters of the subsequent stage's variable reasonably. Based on the mentioned results, a new synthetic Bayesian evaluation program and algorithm framework is put forward to evaluate the multistage reliability growth tests with instant and delayed fix modes. The example shows the effectiveness and flexibility of this method. 展开更多
关键词 reliability growth Bayesian analysis improvement factor multistage test Weibull process
下载PDF
Allelopathic Effects of Adonis vernalis L.: Root Growth Inhibition and Cytogenetic Alterations 被引量:1
13
作者 Asya Pencheva Dragoeva Vanya Petrova Koleva +1 位作者 Zheni Dimitrova Nanova Borislav Petrov Georgiev 《Journal of Agricultural Chemistry and Environment》 2015年第2期48-55,共8页
A possible alternative to synthetic agricultural chemicals is through the use of allelopathy. Adonis species are rich sources of secondary metabolites. Such allelochemicals offer potential for the development of futur... A possible alternative to synthetic agricultural chemicals is through the use of allelopathy. Adonis species are rich sources of secondary metabolites. Such allelochemicals offer potential for the development of future pesticides. Allelochemicals influence plant growth and cause morphological alterations. This visible effect could be due to primary effects at cellular or molecular level. Changes in the mitotic activity and disturbances in different phases of mitotic division are accepted as indicators of cytotoxic influence. Mitotic abnormalities and induction of micronuclei in interphase cells are parameters used to determine genotoxicity. The purpose of the current study was to establish the possible allelopathic effect of Adonis vernalis L. water extracts through evaluation of root growth inhibition effect and cytogenetic alterations. Adonis vernalis L. growing wild in Bulgaria was used in the present study. Two types of water extracts were prepared: Hot and Cold Water Extract of A. vernalis (HWЕА and СWЕА). A 72-h root growth inhibition test was provided in order to determine the toxicity level of extracts. EC50 values were determined. For toxicity test, seeds of Triticum aestivum L. cv. GTW were used. Cytotoxic and genotoxic potential of water extracts (EC50) were evaluated using Allium cepa L.-test. The EC50 for HWEA and CWEA was determined 1.83 g/l and 0.78 g/l respectively. Significant influence on mitotic activity values and a marked decrease in percentage of telophase cells were observed after treatment with both extracts. Adonis extracts also induced different mitotic abnormalities in root-tip cells of Allium cepa L. The percent of interphase cells with micronuclei increased significantly only after treatment with HWEA. The results indicated growth inhibitory, cytotoxic and genotoxic effects of crude water extracts of A. vernalis L. These effects demonstrated the presence of water soluble allelochemicals in Adonis aerial parts. 展开更多
关键词 Adonis vernalis L. ALLELOPATHY ROOT growth INHIBITION ALLIUM cepa-test
下载PDF
Analysis on the Correlation between Stock Exchange and Economic Growth
14
作者 Yuhua Wu Wen Liu 《Chinese Business Review》 2004年第8期16-20,共5页
The problem considered is the correlation between stock exchange and economy growth. Stepwise regression is being used on the following figures: increasing rate of GDP, the volume of stock market, and liquidity. As a... The problem considered is the correlation between stock exchange and economy growth. Stepwise regression is being used on the following figures: increasing rate of GDP, the volume of stock market, and liquidity. As a result, we give .an.equation of national economy and stock market. Then, we use Granger's Causality test to prove that the stock market has positive effects on the national economy. 展开更多
关键词 economy growth stock market regression causality test
下载PDF
家庭社会经济地位对学生社会与情感能力的影响——成长型思维和学业焦虑的链式中介作用 被引量:3
15
作者 刘志 黎佳 梁晨曦 《华东师范大学学报(教育科学版)》 CSSCI 北大核心 2024年第5期83-98,共16页
本研究基于2023年济南参加OECD社会与情感能力测评的数据,聚焦家庭社会经济地位对学生社会与情感能力的影响,并尝试从学生成长型思维和学业焦虑两个视角出发,探讨两个变量在家庭社会经济地位影响学生社会与情感能力的中介机制。研究结... 本研究基于2023年济南参加OECD社会与情感能力测评的数据,聚焦家庭社会经济地位对学生社会与情感能力的影响,并尝试从学生成长型思维和学业焦虑两个视角出发,探讨两个变量在家庭社会经济地位影响学生社会与情感能力的中介机制。研究结果表明:(1)家庭社会经济地位、成长型思维都对学生社会与情感能力产生显著正向影响,学业焦虑对学生社会与情感能力产生显著负向影响;(2)成长型思维发挥着显著正向中介作用,即家庭社会经济地位通过成长型思维的中介作用对学生社会与情感能力产生积极促进作用;(3)学业焦虑作为中介变量呈现显著负向中介效应,表明家庭社会经济地位通过学业焦虑的中介作用对学生社会与情感能力产生不利影响;(4)研究进一步揭示了成长型思维和学业焦虑之间显著正向的链式中介作用,即家庭社会经济地位通过影响学生的成长型思维,进而调节学生的学业焦虑水平,最终对学生社会与情感能力产生综合影响。基于实证结果的讨论,本研究针对学生社会与情感能力发展水平的提升提出三方面建议:一是给予家庭社会经济地位较弱的学生群体更多资源和平台的支持;二是以学校为主阵地,系统建立成长型思维培养的路径机制;三是推进家校联动,共同破解青少年学业焦虑难题。 展开更多
关键词 家庭社会经济地位 成长型思维 学业焦虑 社会与情感能力 中介作用
下载PDF
Investigation of average growth stresses in Cr_2O_3 scales measured by a novel deflection method
16
作者 钱余海 李美栓 +1 位作者 刘光明 辛丽 《中国有色金属学会会刊:英文版》 CSCD 2002年第3期441-444,共4页
The stress in the oxide film plays an important role to keep it intact so it is necessary to determine the stress in the oxide scale. Average growth stresses in Cr 2O 3 scales formed on Ni base alloy (Ni80Cr20) at 1?0... The stress in the oxide film plays an important role to keep it intact so it is necessary to determine the stress in the oxide scale. Average growth stresses in Cr 2O 3 scales formed on Ni base alloy (Ni80Cr20) at 1?000?℃ in air were investigated by a novel deflection technique. It is found that the growth stress in the oxide scale is basically compressive and its average order is 100?MPa. The stress values are high for the thin scales and become low for thick scales after oxidized for 10?h. The planar stress distribution in metals is complex. It is both compressive and tensile at the beginning of oxidation procedure, and then become only tensile during further oxidation. 展开更多
关键词 高温氧化 变形测试 生长压力 镍基合金 氧化铬
下载PDF
全浸腐蚀后焊接接头疲劳裂纹扩展速率分析
17
作者 李岳 赵洋洋 +1 位作者 邓彩艳 龚宝明 《焊接学报》 EI CAS CSCD 北大核心 2024年第9期14-22,共9页
服役于海洋环境中的风力发电机,其塔筒上的焊接结构不可避免地要遭受洋流、风浪、工作过程中带来的疲劳载荷及海洋复杂环境引发的腐蚀,往往成为腐蚀疲劳失效中的薄弱环节,因此,研究焊接接头的腐蚀疲劳现象,探索其背后的运作机制具有十... 服役于海洋环境中的风力发电机,其塔筒上的焊接结构不可避免地要遭受洋流、风浪、工作过程中带来的疲劳载荷及海洋复杂环境引发的腐蚀,往往成为腐蚀疲劳失效中的薄弱环节,因此,研究焊接接头的腐蚀疲劳现象,探索其背后的运作机制具有十分重要的意义.选用S355低合金高强钢作为试验材料,进行S355钢焊接接头在5%NaCl环境中的预腐蚀疲劳裂纹扩展试验.试验结果表明,与未经预腐蚀的试件相比,预腐蚀48 h的试样疲劳裂纹扩展速率并没有明显增加,而预腐蚀336 h的试样疲劳裂纹扩展速率增加显著.利用扫描电子显微镜对预腐蚀后的疲劳试件进行微观表征,观察到在裂纹扩展路径周围存在微裂纹和分支裂纹,表明金属发生了脆化.在预腐蚀疲劳断面上,观察到了裂纹扩展模式的转变,表层金属呈现平面脆性特征,内部金属保留了疲劳韧性特征,微观表征的结果表明,预腐蚀脆化了表层金属,从而加快了试件整体的疲劳裂纹扩展速率. 展开更多
关键词 S355钢 预腐蚀疲劳裂纹扩展试验 脆化
下载PDF
装备测试性工程技术现状与新进展
18
作者 杨鹏 邱静 +3 位作者 苗学问 徐保荣 郝晓辉 刘冠军 《测控技术》 2024年第5期1-22,共22页
装备测试性工程技术起源于20世纪80年代,是先进测试技术与系统工程紧密结合的产物。该技术经过40余年的发展逐渐成熟,在测试性需求分析与分配、测试性建模与方案优化设计、机内测试(Built⁃In Test,BIT)与自动测试系统(Automatic Test Sy... 装备测试性工程技术起源于20世纪80年代,是先进测试技术与系统工程紧密结合的产物。该技术经过40余年的发展逐渐成熟,在测试性需求分析与分配、测试性建模与方案优化设计、机内测试(Built⁃In Test,BIT)与自动测试系统(Automatic Test System,ATS)设计、测试性试验与评估等方面形成了较完善的理论体系,并在各型装备中得到了普遍应用,取得了较大的军事和社会效益。今后测试性基础研究和应用探索究竟该如何开展,未来发展方向是怎样的,是亟需深入探讨的问题。在对测试性工程技术的产生背景与需求、概念与内涵、发展历程、关键技术现状与新进展进行剖析的基础上,指出了目前测试性工程技术研究存在的问题和今后研究突破的方向。 展开更多
关键词 测试性工程 智能机内测试 故障预测与健康管理 数字孪生 测试性增长试验
下载PDF
Physiological and pharmacological basis for the ergogenic effects of growth hormone in elite sports 被引量:3
19
作者 Christer Ehrnborg Thord Rosen 《Asian Journal of Andrology》 SCIE CAS CSCD 2008年第3期373-383,共11页
Growth Hormone (GH) is an important and powerful metabolic hormone that is secreted in a pulsatile pattern from cells in the anterior pituitary, influenced by several normal and pathophysiological conditions. Human ... Growth Hormone (GH) is an important and powerful metabolic hormone that is secreted in a pulsatile pattern from cells in the anterior pituitary, influenced by several normal and pathophysiological conditions. Human GH was first isolated in the 1950s and human derived cadaveric GH was initially used to treat patients with GH deficiency. However, synthetic recombinant GH has been widely available since the mid-1980s and the advent of this recombi- nant GH boosted the abuse of GH as a doping agent. Doping with GH is a well-known problem among elite athletes and among people training at gyms, but is forbidden for both medical and ethical reasons. It is mainly the anabolic and, to some extent, the lipolytic effects of GH that is valued by its users. Even though GH' s rumour as an effective ergogenic drug among athletes, the effectiveness of GH as a single doping agent has been questioned during the last few years. There is a lack of scientific evidence that GH in supraphysiological doses has additional effects on muscle exercise performance other than those obtained from optimised training and diet itself. However, there might be synergistic effects if GH is combined with, for example, anabolic steroids, and GH seems to have positive effect on collagen synthesis. Regardless of whether or not GH doping is effective, there is a need for a reliable test method to detect GH doping. Several issues have made the development of a method for detecting GH doping complicated but a method has been presented and used in the Olympics in Athens and Turin. A problem with the method used, is the short time span (24-36 hours) from the last GH administration during which the test effectively can reveal doping. Therefore, out-of-competition testing will be crucial. However, work with different approaches to develop an alternative, reliable test is ongoing. 展开更多
关键词 growth hormone IGF-I doping doping test ATHLETES maximum exercise test supraphysiological anabolic androgenic steroids bone markers
下载PDF
果胶酶提取西番莲果皮多糖的抗氧化和益生菌增殖活性 被引量:1
20
作者 王秀丽 薛登萍 +3 位作者 易良 李丽芬 李静 李霞 《食品与发酵工业》 CAS CSCD 北大核心 2024年第18期194-200,208,共8页
该文以西番莲果皮为原料,采用酶法辅助提取果皮多糖并对其抗氧化和益生菌增殖活性进行研究。通过正交试验优化西番莲果皮多糖提取参数;通过测定其还原能力,及对DPPH自由基和羟自由基的清除率来考察其抗氧化活性;将西番莲果皮多糖作唯一... 该文以西番莲果皮为原料,采用酶法辅助提取果皮多糖并对其抗氧化和益生菌增殖活性进行研究。通过正交试验优化西番莲果皮多糖提取参数;通过测定其还原能力,及对DPPH自由基和羟自由基的清除率来考察其抗氧化活性;将西番莲果皮多糖作唯一碳源,研究其对植物乳杆菌(Lactobacillus plantarum)、德氏乳杆菌保加利亚亚种(L.delbrueckii(subsp.)bulgaricus)、短乳杆菌(L.brevis)和嗜热链球菌(Streptococcus thermophilus)的体外增殖作用。结果表明,提取条件为:果胶酶添加量5 mg/mL,pH 4.5,提取时间2 h,提取温度40℃,此条件下,多糖得率为15.83%。西番莲果皮多糖有较好的还原能力,并对DPPH自由基和羟自由基有较好的清除率,呈现剂量依赖关系。西番莲果皮多糖对上述4种菌均有一定的增殖作用,最大生长速率排序为:植物乳杆菌(0.1599)>嗜热链球菌(0.1395)>短乳杆菌(0.1251)>德氏乳杆菌保加利亚亚种(0.1239)。西番莲果皮多糖是一种天然的食品抗氧化剂和益生元物质,有很好的市场前景。 展开更多
关键词 西番莲多糖 果胶酶 正交试验 抗氧化活性 益生菌增殖
下载PDF
上一页 1 2 107 下一页 到第
使用帮助 返回顶部