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Climate-Vegetation Coverage Interactions in the Hengduan Mountains Area, Southeastern Tibetan Plateau, and Their Downstream Effects
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作者 Congxi FANG Jinlei CHEN +4 位作者 Chaojun OUYANG Lu WANG Changfeng SUN Quan ZHANG Jun WEN 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2024年第4期701-716,共16页
Little is known about the mechanism of climate-vegetation coverage coupled changes in the Tibetan Plateau(TP)region,which is the most climatically sensitive and ecologically fragile region with the highest terrain in ... Little is known about the mechanism of climate-vegetation coverage coupled changes in the Tibetan Plateau(TP)region,which is the most climatically sensitive and ecologically fragile region with the highest terrain in the world.This study,using multisource datasets(including satellite data and meteorological observations and reanalysis data)revealed the mutual feedback mechanisms between changes in climate(temperature and precipitation)and vegetation coverage in recent decades in the Hengduan Mountains Area(HMA)of the southeastern TP and their influences on climate in the downstream region,the Sichuan Basin(SCB).There is mutual facilitation between rising air temperature and increasing vegetation coverage in the HMA,which is most significant during winter,and then during spring,but insignificant during summer and autumn.Rising temperature significantly enhances local vegetation coverage,and vegetation greening in turn heats the atmosphere via enhancing net heat flux from the surface to the atmosphere.The atmospheric heating anomaly over the HMA thickens the atmospheric column and increases upper air pressure.The high pressure anomaly disperses downstream via the westerly flow,expands across the SCB,and eventually increases the SCB temperature.This effect lasts from winter to the following spring,which may cause the maximum increasing trend of the SCB temperature and vegetation coverage in spring.These results are helpful for estimating future trends in climate and eco-environmental variations in the HMA and SCB under warming scenarios,as well as seasonal forecasting based on the connection between the HMA eco-environment and SCB climate. 展开更多
关键词 Hengduan Mountains Area normalized difference vegetation index climate change net heat flux downstream effects
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Numerical investigation of the effects of soil-structure and granular material-structure interaction on the seismic response of a flat-bottom reinforced concrete silo
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作者 Sonia Benkhellat Mohammed Kadri Abdelghani Seghir 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2024年第3期609-623,共15页
In this work,a numerical study of the effects of soil-structure interaction(SSI)and granular material-structure interaction(GSI)on the nonlinear response and seismic capacity of flat-bottomed storage silos is conducte... In this work,a numerical study of the effects of soil-structure interaction(SSI)and granular material-structure interaction(GSI)on the nonlinear response and seismic capacity of flat-bottomed storage silos is conducted.A series of incremental dynamic analyses(IDA)are performed on a case of large reinforced concrete silo using 10 seismic recordings.The IDA results are given by two average IDA capacity curves,which are represented,as well as the seismic capacity of the studied structure,with and without a consideration of the SSI while accounting for the effect of GSI.These curves are used to quantify and evaluate the damage of the studied silo by utilizing two damage indices,one based on dissipated energy and the other on displacement and dissipated energy.The cumulative energy dissipation curves obtained by the average IDA capacity curves with and without SSI are presented as a function of the base shear,and these curves allow one to obtain the two critical points and the different limit states of the structure.It is observed that the SSI and GSI significantly influence the seismic response and capacity of the studied structure,particularly at higher levels of PGA.Moreover,the effect of the SSI reduces the damage index of the studied structure by 4%. 展开更多
关键词 reinforced concrete silo perfectly matched layers soil-structure interaction granular material-structure interaction effective seismic input method damage index
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Evaluation of Spectral Scale Effects in Estimation of Vegetation Leaf Area Index Using Spectral Indices Methods 被引量:5
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作者 DU Huishi JIANG Hailing +2 位作者 ZHANG Lifu MAO Dehua WANG Zongming 《Chinese Geographical Science》 SCIE CSCD 2016年第6期731-744,共14页
Spectral index methodology has been widely used in Leaf Area Index(LAI) retrieval at different spatial scales. There are differences in the spectral response of different remote sensors and thus spectral scale effect ... Spectral index methodology has been widely used in Leaf Area Index(LAI) retrieval at different spatial scales. There are differences in the spectral response of different remote sensors and thus spectral scale effect generated during the use of spectral indices to retrieve LAI. In this study, PROSPECT, leaf optical properties model and Scattering by Arbitrarily Inclined Layers(SAIL) model, were used to simulate canopy spectral reflectance with a bandwidth of 5 nm and a Gaussian spectral response function was employed to simulate the spectral data at six bandwidths ranging from 10 to 35 nm. Additionally, for bandwidths from 5 to 35 nm, the correlation between the spectral index and LAI, and the sensitivities of the spectral index to changes in LAI and bandwidth were analyzed. Finally, the reflectance data at six bandwidths ranging from 40 to 65 nm were used to verify the spectral scale effect generated during the use of the spectral index to retrieve LAI. Results indicate that Vegetation Index of the Universal Pattern Decomposition(VIUPD) had the highest accuracy during LAI retrieval. Followed by Normalized Difference Vegetation Index(NDVI), Modified Simple Ratio Indices(MSRI) and Triangle Vegetation Index(TVI), although the coefficient of determination R^2 was higher than 0.96, the retrieved LAI values were less than the actual value and thus lacked validity. Other spectral indices were significantly affected by the spectral scale effect with poor retrieval results. In this study, VIUPD, which exhibited a relatively good correlation and sensitivity to LAI, was less affected by the spectral scale effect and had a relatively good retrieval capability. This conclusion supports a purported feature independent of the sensor of this model and also confirms the great potential of VIUPD for retrieval of physicochemical parameters of vegetation using multi-source remote sensing data. 展开更多
关键词 光谱索引 植被叶区域索引 放射的转移模型 光谱反应 规模效果
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Effect of Alligator Pepper on Litter Weight of Rats Fed on High Glycemic Index Diet
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作者 Ute Inegbenebor Festus Eghomwanre 《Food and Nutrition Sciences》 2017年第8期793-800,共8页
This study was carried out to find out if alligator pepper can prevent the development of fetal macrosomia in Sprague-Dawley rats fed with high glycemic index diet. Fifteen adult female Sprague-Dawley rats of proven f... This study was carried out to find out if alligator pepper can prevent the development of fetal macrosomia in Sprague-Dawley rats fed with high glycemic index diet. Fifteen adult female Sprague-Dawley rats of proven fertility were acclimatized for a period of two weeks in a well-ventilated laboratory and fed with grower’s mash and water ad libitum. Thereafter, they were randomly placed in separate cages after which a male Sprague-Dawley rat of proven fertility was introduced into each of the cages containing the female rats. They were left in the cages for three days during, which mating was confirmed to have occurred. The male rats were then withdrawn from the female rats, which were placed in separate maternity cages. The female rats were randomly allocated to three groups A, B and C so there were 5 pregnant rats in each group. The rats in group A were fed with 50 g of grower’s mash daily while the rats in groups B and C were fed with 50 g of cooked fermented cassava respectively. All rats were given water ad libitum throughout the duration of the experiment. The rats in groups A and B were intraperitoneally injected with 13.3 ml per Kg body weight of distilled water while the rats in group C were intraperitoneally injected with 13.3 mg/Kg body weight of aqueous extract of alligator pepper respectively. They were observed for 18 - 25 days. The litters of the rats in group B had a significantly higher mean weight than the rats in group A while the litters of the rats in group C had a significantly lower mean weight than the rats in groups B. It was concluded that intraperitoneally injected aqueous extract of alligator pepper, in the first trimester of pregnancy, can prevent the development of fetal macrosomia in Sprague-Dawley rats. 展开更多
关键词 effect ALLIGATOR PEPPER HIGH Glycemic index DIET LITTER Weight Sprague Dawley Rat
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On the Validity of the Effective Index Method for Long Period Grating Photonic Crystal Fibers
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作者 Dhia Khadri Walid Belhadj +2 位作者 Douha Gamra Fathi AbdelMalek Habib Bouchriha 《Materials Sciences and Applications》 2012年第5期310-316,共7页
This paper focuses on the investigation of modal characteristics and sensing properties of long period grating photonic crystal fibers (LPG-PCFs). An improved effective index method is employed with an objective to st... This paper focuses on the investigation of modal characteristics and sensing properties of long period grating photonic crystal fibers (LPG-PCFs). An improved effective index method is employed with an objective to study its limitations for various designs of LPG-PCFs. Results so obtained with the above method are compared with the corresponding values of multiple multipole (MMP) method results which points the range of validity and applicability of the improved effective index method to LPG-PCFs. It is shown that this method is excellent when the surrounding media is assumed to be air. However, it becomes less accurate when the fiber is immersed into a liquid with a refractive index close to that of the cladding. 展开更多
关键词 Long Period GRATINGS Photonic Crystal Fiber (LPG-PCF) Improved effective index MMP CLADDING MODES Sensor Sensitivity
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Effect of successive irrigation of subarachnoid cavity on body temperature and cerebrospinal fluid-related index in suppurative meningitis model dogs
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作者 Yong Liu Guohou He +2 位作者 Yuanyuan Wang Xueqiang Chen Qibin Wang 《Neural Regeneration Research》 SCIE CAS CSCD 2006年第2期108-110,共3页
BACKGROUND: At present, suppurative meningitis is mainly treated through anti-infection with antibiotics, depressing encephalic pressure with mannitol , lowering body temperature with drugs , supporting treatment, et... BACKGROUND: At present, suppurative meningitis is mainly treated through anti-infection with antibiotics, depressing encephalic pressure with mannitol , lowering body temperature with drugs , supporting treatment, etc. However, Jt takes a long course of treatment and has poor therapeutic effect. Successive irrigation of subarachnoid cavity maybe have better effect on suppurative meningitis.OBJECTIVE: We compared the successive irrigation of subbarachnoid cavity with routine therapeutic methods to observe the effect of successive irrigation of subarachnoid cavity on the body temperature, cerebrospinal fluid pressure, the number of white blood cell and the level of protein of suppurative meningitis dogs. DESIGN: A randomized and controlled animal experiment SETTING: Institute of Neuroscience, Taihe Hospital Affiliated to Yunyang Medical College MATERIALS: Totally 17 healthy adult male Beagle dogs, of common grade, weighing 9 to 10 kg, were involved in the experiment, and raised in the 20 ℃ temperature with relative humidity of 50% for 1 week. They were randomized into 3 groups: normal group (n=5), control group (n=5) and irrigation group (n=6). Artificial cerebrospinal fluid was prepared according to the level of glucose and chloride of cerebrospinal fluid of normal dogs, and then it was sterilized with high pressure. METHODS : This experiment was carried out in the experimental animal center of Yunyang Medical College from April to August 2001. ① After the dogs were anesthetized,1 mL fresh staphylococcus aureus liquid [(1.5-1.6)× 10^9 L 1] was injected into medullary cistern to establish suppurative meningitis models. ② After models were successfully established, intravenous drip infusion of 1.2 ×10^6 U/(kg.d), muscular injection of sulfadiazine sodium of 100 mg/(kg.d )and intravenous injection of 200 g/L mannitol of 5 g/(kg .time) for 3 times a day were performed in the control group. The irrigation of subarachnoid meningitis was conducted in the irrigation group besides the routine treatments in the control group: Artificial cerebrospinal fluid was successively injected into the epidural catheter in the waist part. The mixtures of artificial cerebrospinal fluid and inflammatory cerebrospinal fluid flowed out incessantly from epidural catheter of medullary cistern. Irrigation was ended 48 hours later. Dogs were routinely raised in the control group. ③ From the first day after being modeled to the 14^th day after treatment, the rectal temperatures were daily measured in the morning, at noon and in the evening respectively, then the mean temperatures were calculated. From the 2^nd day after being modeled to the 14^th day after treatment, puncture at waist was given once, and the cerebrospinal fluid pressure, the number of white blood cells and the level of protein were measured. MAIN OUTCOME MEASURES : The body temperature, cerebrospinal fluid pressure, the number of white blood cells and the level of protein were measured on suppurative meningitis model dogs. RESULTS" Totally 17 Beagle dogs were involved in this study.①The body temperatures of dogs were significantly reduced in the control group and in irrigation group on the 1^st day after treatment and lower than suppurative meningitis model dogs on the 2^nd day after being modeled (P 〈 0.05). The body temperatures were gradually decreased in control group from the 2^nd day after being modeled to the 14^th day after treatment (P 〈 0.01), but were significantly higher than those of dogs in normal group on the 14^th day after treatment (P 〈 0.05). The body temperatures of dogs were gradually decreased in irrigation group on the 2^nd day or 3^rd day after treatment (P 〈 0.01) and then were close to the normal body temperature on the 14^th day after treatment. ②There was the same cerebrospinal fluid pressure in control group as in irrigation group on the 2^nd day after being modeled (P 〉 0.05), but significantly decreased in two groups from the 1s' day or 2^nd day after treatment (P 〈 0.01), and cerebrospinal fluid pressure was close to the normal level in irrigation group. Although the cerebrospinal fluid pressure raised a little on the 3^rd day or 4^th day after treatment in the irrigation group (P〈 0.05), but recovered to the normal level on the 9^th day after treatment again. It decreased slowly in the control group and still was sig- nificantly higher than normal group on the 14^hd day after treatment (P〈 0.01 ). ③No significant difference existed in number of white blood cell and the level of protein between control group and irrigation group on the 2^nd day following modeled. Both of them began to significantly decrease on the 1^st and 2^nd day after treatment (P 〈 0.01 ). Although the number of white blood cell and the level of protein rebounded a little in irrigation group 3 or 4 days after treatment (P〈 0.05), they were gradually decreased and recovered to normal levels on the 13^th day after treatment. The number of white blood cell and the level of protein slowly decreased in the control group compared with irrigation group and were still significantly higher than normal group on the 14^th day (P〈 0.01 ). EONELUSEON : Irrigation of subarachnoid cavity can decrease the body temperature, cerebrospinal fluid pressure, the number of white blood cells and the level of protein at early stage of suppurative meningitis, and the therapeutic effect is better than that of routine treatment. 展开更多
关键词 body effect of successive irrigation of subarachnoid cavity on body temperature and cerebrospinal fluid-related index in suppurative meningitis model dogs
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Research on Affordability Modeling of Aircraft Based on Effectiveness Indexes
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作者 YAN Sheng-wen GUO Ji-han 《International Journal of Plant Engineering and Management》 2011年第1期15-20,共6页
With the cost estimation of military aircraft as the research object, this paper aims to study the contradiction between the choice of explanatory variables in index modeling and the maintaining of model validity. It ... With the cost estimation of military aircraft as the research object, this paper aims to study the contradiction between the choice of explanatory variables in index modeling and the maintaining of model validity. It analyzes and establishes a cost estimation modeling concept based on an Effectiveness Index and studies the way to construct Effectiveness Indexes for the sake of cost estimation modeling. Based on a case study, the paper establishes and analyzes the Effectiveness Index-based cost estimation models and DAPCA (Development And Procurement Costs of Aircraft) models developed by the RAND Corparation . The comparison of these models shows that the Effective- ness Index-based cost parameter models not only comprehensively consider the obvious driving parameter indexes of the cost, but reduces the variables of regressive analysis, hence giving the model a higher reliability. 展开更多
关键词 military aircraft effectiveness index AFFORDABILITY COST parameter model
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Effects of leaf N concentration and leaf area index on determining rice tillering
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《Chinese Rice Research Newsletter》 1999年第4期8-9,共2页
Relative tillering rate(RTR)increased linear-ly with the increasing of leaf N concentration(NLV)has been already reported.To testwhether this relationship could be used toquantitatively explain the difference in tille... Relative tillering rate(RTR)increased linear-ly with the increasing of leaf N concentration(NLV)has been already reported.To testwhether this relationship could be used toquantitatively explain the difference in tilleringamong a wide range of N application,field ex- periments were conducted at the IRRI farm,Los Banos,Laguna,the Philippines.Two in- dica cultivars,IR 72 and IR68284H wereused.For each cultivar,12 treatments includ- ing 4 N levels(0,60,120,and 180kgN·ha)and 3 transplanting spacing(30×20,20×20,and 10×20cm)were arranged in a ran-domized split-plot design with 4 replications.The N treatments were designated as mainplots and spacings as subplots.Fourteen-day-old seedlings were transplanted with 3seedlings per hill.The subplot area was 20m~2.Nitrogen fertilizer was applied as basal,atmidtillering,and at panicle initiation in threeequal splits.P,K,and Zn were applied asbasal at normal dosage.The field was flooded.Plant samples were taken every 7-14 d from 14d after transplanting to flower 展开更多
关键词 area IR effects of leaf N concentration and leaf area index on determining rice tillering
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Automatic Variable Selection for Single-Index Random Effects Models with Longitudinal Data
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作者 Suigen Yang Liugen Xue 《Open Journal of Statistics》 2014年第3期230-237,共8页
We consider the problem of variable selection for the single-index random effects models with longitudinal data. An automatic variable selection procedure is developed using smooth-threshold. The proposed method share... We consider the problem of variable selection for the single-index random effects models with longitudinal data. An automatic variable selection procedure is developed using smooth-threshold. The proposed method shares some of the desired features of existing variable selection methods: the resulting estimator enjoys the oracle property;the proposed procedure avoids the convex optimization problem and is flexible and easy to implement. Moreover, we use the penalized weighted deviance criterion for a data-driven choice of the tuning parameters. Simulation studies are carried out to assess the performance of our method, and a real dataset is analyzed for further illustration. 展开更多
关键词 VARIABLE SELECTION Single-index MODEL RANDOM effects Longitudinal DATA
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Study on Multi-effect Time Parameters of Ergonomic Validity Index in Low-carbon Residential Kitchen
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作者 Jun Ji Hong Jin 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2014年第5期52-58,共7页
In the study on functional low-carbon ergonomic validity in buildings,ergonomic validity is different from resource validity which is easy for quantitative analysis. To eliminate the complexity and uncertainty impacts... In the study on functional low-carbon ergonomic validity in buildings,ergonomic validity is different from resource validity which is easy for quantitative analysis. To eliminate the complexity and uncertainty impacts of human factors on quantitative study,it proposes a method of building a parameter of ergonomic validity—multi-effect time by using cardiotachometer to record heart rate change,being used to evaluate the functional low-carbon ergonomic validity targeting at the ontological characteristics of kitchen. This method is used to determine the physical consumption intensity( multi-effect) through heart rate incremental relation based on the principles of physiology and ergonomics,and to confirm the ergonomic validity of environmental factors by the time to complete standard work as well as multi-effect quantitative analysis. The test results show that,under the kitchen operating conditions,the multi-effect( ME) can properly reflect the real-time status of the operator and is easily operated; the parameters obtained are not significantly related to the physiological status of the operator,and multi-effect time( MT) is sensitive to the physical consumption brought about to the operator due to kitchen environmental factors; thus,it can be taken as an objective index,which is simple and easy to operate in residential kitchen functional low-carbon evaluation. 展开更多
关键词 functional low-carbon human factors ergonomic validity index basal heart rate increment ratio multi-effect time of kitchen work
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氯酯磺草胺与甲咪唑烟酸复配防除香附子效果及对紫花苜蓿安全性
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作者 苏旺苍 杨慕菡 +3 位作者 薛飞 孙兰兰 徐洪乐 吴仁海 《草业科学》 CAS CSCD 北大核心 2024年第2期416-424,共9页
为明确氯酯磺草胺与甲咪唑烟酸应用于紫花苜蓿(Medicago sativa)田的可行性,在温室和田间测定了氯酯磺草胺和甲咪唑烟酸复配对香附子(Cyperus rotundus)的防效和紫花苜蓿的安全性。温室试验表明,氯酯磺草胺和甲咪唑烟酸复配对香附子具... 为明确氯酯磺草胺与甲咪唑烟酸应用于紫花苜蓿(Medicago sativa)田的可行性,在温室和田间测定了氯酯磺草胺和甲咪唑烟酸复配对香附子(Cyperus rotundus)的防效和紫花苜蓿的安全性。温室试验表明,氯酯磺草胺和甲咪唑烟酸复配对香附子具有很好的防除效果,两者按有效成分用量比1:2~1:4配比对香附子株高和鲜重的共毒系数分别介于131.54~150.46和152.84~180.25,呈明显增效作用,其中1:3的比例配伍的增效最为明显,对紫花苜蓿和香附子之间的株高和鲜重选择性指数分别为1.86和1.56。两地田间试验表明,氯酯磺草胺和甲咪唑烟酸(17.50+52.50)~(25.00+75.00) g·hm^(-2)复配处理对郑州和兰考两地的香附子株防效分别为78.5%~88.5%和82.1%~90.8%、鲜重防效分别为83.4%~92.7%和84.7%~93.6%,增产率分别为28.8%~35.1%和30.5%~38.3%,显著高于氯酯磺草胺和甲咪唑烟酸单用,且避免了单用氯酯磺草胺和甲咪唑烟酸的药害问题,提高了对紫花苜蓿的安全性,表明甲咪唑烟酸和氯酯磺草胺复配可有效防控香附子,对紫花苜蓿的安全性较好,具有良好推广应用前景。 展开更多
关键词 株高 鲜重 药害 防效 增效 共毒系数 选择性指数
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慢性牙周炎患者龈沟液miR-155、miR-21水平及其临床意义
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作者 郭娇娇 卢丽先 +3 位作者 巩兰平 张学强 李蕾 刘英奇 《检验医学与临床》 CAS 2024年第7期889-894,共6页
目的检测慢性牙周炎(CP)患者龈沟液中微小RNA-155(miR-155)、微小RNA-21(miR-21)表达水平变化及其临床意义。方法选择2021年10月至2022年10月该院142例CP患者作为CP组,根据牙周炎严重程度分为轻度CP组、中度CP组、重度CP组。随访1个月,... 目的检测慢性牙周炎(CP)患者龈沟液中微小RNA-155(miR-155)、微小RNA-21(miR-21)表达水平变化及其临床意义。方法选择2021年10月至2022年10月该院142例CP患者作为CP组,根据牙周炎严重程度分为轻度CP组、中度CP组、重度CP组。随访1个月,根据临床疗效分为疗效良好组、疗效较差组。同期142例健康志愿者作为对照组。采用实时荧光定量聚合酶链反应检测龈沟液miR-155、miR-21表达水平。利用Pearson相关分析CP患者龈沟液miR-155、miR-21表达水平与牙龈指数(GI)、牙槽骨吸收程度(ABL)、探诊深度(PD)、附着丧失(AL)的相关性。采用多因素Logistic回归分析CP患者疗效的影响因素,采用受试者工作特征(ROC)曲线评估miR-155、miR-21对CP患者疗效的预测价值。结果CP组miR-155、miR-21表达水平高于对照组(P<0.05)。CP组PD、AL、ABL、GI明显高于对照组(P<0.05)。轻度CP组、中度CP组、重度CP组miR-155、miR-21表达水平依次升高(P<0.05)。疗效较差组miR-155、miR-21表达水平高于疗效良好组(P<0.05)。龈沟液miR-155、miR-21表达水平均与PD、AL、ABL、GI呈正相关(P<0.05)。多因素Logistic回归分析显示,病情严重程度、miR-155、miR-21是CP患者疗效的影响因素(P<0.05)。ROC曲线分析结果显示,miR-155、miR-21预测CP患者疗效较差的曲线下面积(AUC)分别为0.937(95%CI:0.888~0.986)、0.818(95%CI:0.715~0.921),二者联合预测的AUC为0.960(95%CI:0.920~0.998),优于单一指标预测。结论CP患者龈沟液miR-155、miR-21表达水平升高,与牙周炎严重程度、牙周临床指标及临床疗效有关,2项指标或可作为CP患者疗效的潜在预测标志物。 展开更多
关键词 慢性牙周炎 微小RNA-155 微小RNA-21 疗效 牙龈指数 牙槽骨吸收程度
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长白山区4种针叶林有效叶面积指数遥感精细反演及空间分布规律
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作者 包广道 刘婷 +4 位作者 张忠辉 任志彬 翟畅 丁铭铭 姜雪菲 《林业科学》 EI CAS CSCD 北大核心 2024年第5期127-138,共12页
[目的]研究快速、准确、宏观获取不同森林类型有效叶面积指数(LAI_(e))的方法,探讨其空间分布规律,为中小尺度森林LAI_(e)遥感产品的开发提供新思路,为林业精细化监测和森林生态系统碳水循环模拟提供科学可靠的技术手段。[方法]以长白... [目的]研究快速、准确、宏观获取不同森林类型有效叶面积指数(LAI_(e))的方法,探讨其空间分布规律,为中小尺度森林LAI_(e)遥感产品的开发提供新思路,为林业精细化监测和森林生态系统碳水循环模拟提供科学可靠的技术手段。[方法]以长白山为研究区,基于Sentinel-2A多光谱影像,运用三维卷积神经网络提取研究区4种针叶林型(长白落叶松、樟子松、红松和红皮云杉)的空间分布;采用区分林型和全样本2种方案,分析样地实测LAI_(e)与7种植被指数(增强植被指数、反红边叶绿素指数、改进简单植被指数、归一化水体指数、归一化植被指数、土壤调节植被指数、简单植被指数)的相关关系;利用各林型对应的最优植被指数,构建区分林型和全样本LAI_(e)与植被指数的回归模型,并基于验证样本数据对比区分林型模型、全样本模型和PROSAIL模型在LAI_(e)反演中的精度表现;结合地理因子分析4种针叶林型LAI_(e)空间格局及变化规律。[结果]所有样本组中7种植被指数与相对的LAI_(e)均存在极显著相关关系(P<0.01),除增强植被指数(EVI)与红松LAI_(e)、简单植被指数(SR)与红皮云杉LAI_(e)外,相关系数均大于0.6,但组间LAI_(e)与不同植被指数相关性具有较大差异;红松、长白落叶松和樟子松LAI_(e)与反红边叶绿素指数(IRECI)相关性最高,红皮云杉、红松LAI_(e)分别与EVI、改进简单植被指数(MSR)相关性最高;4种不同林型模型比全样本模型的R2提高12.7%以上,RMSE降低34.5%;研究区内4种林型LAI_(e)范围在0.37~5.86之间,平均LAI_(e)由高至低依次为红松、长白落叶松、樟子松、红皮云杉。红松对海拔、坡度、坡向的变化最为敏感,红皮云杉、樟子松次之,长白落叶松最小。[结论]不同林型LAI_(e)与遥感植被指数的相关程度存在明显差异,区分林型构建回归模型能够提高LAI_(e)反演精度;区分林型后拟合的线性模型精度整体较PROSAIL模型和全样本模型更高,但LAI_(e)高值区域没有PROSAIL模型表现稳定;4种针叶林型LAI_(e)对地理因子变化的反应差异较大。本研究可为精细区分森林类型的中小尺度针叶林LAI_(e)遥感反演研究提供参考。 展开更多
关键词 有效叶面积指数 针叶树种 森林类型 卫星遥感 空间分布规律
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预防性加温输液在急诊严重创伤患者中的应用
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作者 陈浩 胡佳颖 管佳慧 《中国医药导报》 CAS 2024年第4期192-195,200,共5页
目的 探讨预防性加温输液在急诊严重创伤患者中的应用效果。方法 选取2022年1月至12月上海市第六人民医院收治的急诊严重创伤患者84例,采用随机数字表法分为对照组(42例)和观察组(42例)。对照组采用常规干预和常规保温措施,观察组在对... 目的 探讨预防性加温输液在急诊严重创伤患者中的应用效果。方法 选取2022年1月至12月上海市第六人民医院收治的急诊严重创伤患者84例,采用随机数字表法分为对照组(42例)和观察组(42例)。对照组采用常规干预和常规保温措施,观察组在对照组的基础上进行预防性加温输液。比较两组体温值、凝血指标和酸碱指标变化,28 d存活率,寒战、低体温发生率。结果 两组体温组间、时间点及交互作用比较,差异有统计学意义(P<0.05)。进一步两两比较,组内比较:两组组内各时间点体温值比较,差异无统计学意义(P>0.05);组间比较:观察组入院后4、8、12、24 h体温值高于对照组,差异有统计学意义(P<0.05)。两组TT水平组间、时间点及交互作用比较,差异有统计学意义(P<0.05)。其中,两组入院后24 h TT水平高于入院时,观察组入院6、12、24 h TT水平低于对照组,差异有统计学意义(P<0.05)。两组不同时间FIB水平比较,差异有统计学意义(P<0.05)。其中两组入院后24 h FIB水平低于入院时,差异有统计学意义(P<0.05)。两组不同时间点血乳酸水平比较,差异有统计学意义(P<0.05)。其中两组入院后6、12、24 h血乳酸水平高于入院时,差异有统计学意义(P<0.05)。两组p H值水平组间、时间点比较,差异有统计学意义(P<0.05)。其中两组入院后6、12、24 h p H值水平低于入院时,差异有统计学意义(P<0.05)。观察组寒战、低体温发生率低于对照组,差异有统计学意义(P<0.05)。两组28 d存活率比较,差异无统计学意义(P>0.05)。结论 预防性加温输液可减少寒战和低体温的发生,并改善患者凝血功能。 展开更多
关键词 预防性 加温输液 严重创伤 复温效果 凝血功能 酸碱指标
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基于FAST和Sobol指数法的雷达系统效能敏感性分析
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作者 胡涛 申立群 +2 位作者 朱镜达 孙成会 董伟锋 《系统工程与电子技术》 EI CSCD 北大核心 2024年第2期561-569,共9页
为了以较小的代价快速提升对空探测雷达系统的综合效能,首先搭建了对空探测雷达系统综合效能的评估指标体系,在此基础上完成了综合效能评估模型的建立。选择两种基于方差原理的全局敏感性分析方法,即傅里叶幅度敏感性测试(Fourier ampli... 为了以较小的代价快速提升对空探测雷达系统的综合效能,首先搭建了对空探测雷达系统综合效能的评估指标体系,在此基础上完成了综合效能评估模型的建立。选择两种基于方差原理的全局敏感性分析方法,即傅里叶幅度敏感性测试(Fourier amplitudes sensitivity test,FAST)和Sobol指数法,分别从频域和时域对建立的评估模型进行敏感性分析。在基于FAST进行敏感性分析时,提出了21维输入指标所对应的特征频率集的选取方法;在基于Sobol指数法进行敏感性分析时,考虑了二阶及高阶敏感性指数的影响。对比FAST和Sobol指数法的分析结果,两种方法获得的敏感性分析结果具有较好的一致性。其中,功率和频率为对空探测雷达系统的主要影响指标,为雷达系统的研发和升级提供了可靠性依据。 展开更多
关键词 雷达系统 效能评估 敏感性分析 傅里叶幅度敏感性测试 Sobol指数法
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钢筋混凝土拱桥主拱圈加固方式及效果研究
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作者 徐略勤 潘锐华 +2 位作者 周水兴 岳克锋 沈正璇 《沈阳建筑大学学报(自然科学版)》 CAS 北大核心 2024年第2期250-258,共9页
目的 寻求钢筋混凝土拱桥主拱圈最佳加固方式,以改善加固效果,给同类危旧拱桥加固提供参考。方法 基于某实际加固桥例提出3种不同卸载方式的加固改造方案,采用Midas civil软件建立有限元模型,分析不同加固方式的影响规律;对原拱圈初始... 目的 寻求钢筋混凝土拱桥主拱圈最佳加固方式,以改善加固效果,给同类危旧拱桥加固提供参考。方法 基于某实际加固桥例提出3种不同卸载方式的加固改造方案,采用Midas civil软件建立有限元模型,分析不同加固方式的影响规律;对原拱圈初始应力水平、施工阶段内力、成桥状态下应力、内力及挠度进行分析;利用加固层最大应力比、荷载置换率和挠度变化率对加固效果进行评价。结果 方案三的加固层最大应力比分别比方案一、二大45.12%与52.74%,荷载置换效果最显著,最大值达3.82,挠度变化率最大。结论 选择拱上建筑拆除得越多的方式进行加固,加固效果越好;对钢筋混凝土拱桥进行加固时,应基于加固方式制定加固施工方案,同时需考虑施工工期与加固成本。 展开更多
关键词 钢筋混凝土拱桥 增大截面法 加固方式 加固效果 加固指标 卸载
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无人机自主作战效能评估技术研究综述
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作者 刘树光 邵明军 《电光与控制》 CSCD 北大核心 2024年第4期55-64,共10页
无人机自主作战效能评估是衡量无人机在特定作战条件下能否运用自主能力完成预定目标任务的有效途径,是无人机自主作战技术论证和装备体系建设发展的核心问题。从无人机作战效能基本问题出发,首先,剖析无人机自主性与自主能力以及自主... 无人机自主作战效能评估是衡量无人机在特定作战条件下能否运用自主能力完成预定目标任务的有效途径,是无人机自主作战技术论证和装备体系建设发展的核心问题。从无人机作战效能基本问题出发,首先,剖析无人机自主性与自主能力以及自主作战能力与自主作战效能的基本概念,给出无人机自主作战效能评估的基本流程;其次,分别从任务视角和原理角度对无人装备作战效能评估指标体系、评估方法的研究现状进行综述,归纳总结3类指标体系构建的现状和4类效能评估方法进展;最后,梳理当前评估中存在的问题,展望无人机效能评估技术的发展趋势。相关研究可为后续无人机自主作战效能评估提供技术参考和方向指导,具有重要的军事意义。 展开更多
关键词 无人机 自主作战 作战效能 指标体系 评估方法
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平台型医学课程在线教学学习效果评价指标与评价标准研究
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作者 樊瑛 程晓多 +4 位作者 梁霄 潘玉娇 温荔媛 王鸿慧 倪金金 《中国中医药现代远程教育》 2024年第6期200-202,共3页
当前,中国高等教育正积极推动高质量发展,提升高等教育在线课程教学质量是我国高等教育实现“变道超车”的重要战略步骤。就医学课程而言,深入研究平台型医学课程在线教学学习效果评价指标与评价标准是进行学习效果评价的重要前提,是提... 当前,中国高等教育正积极推动高质量发展,提升高等教育在线课程教学质量是我国高等教育实现“变道超车”的重要战略步骤。就医学课程而言,深入研究平台型医学课程在线教学学习效果评价指标与评价标准是进行学习效果评价的重要前提,是提升平台型医学课程在线教学质量的重要基础。根据“以学生发展为中心”的教育理念,以学习效果评价有利于促进学生与教师发展为宗旨,以医学本科生培养目标、毕业要求、课程目标为具体内容,提出平台型医学课程在线教学学习效果评价指标与评价标准,为平台型医学课程在线教学学习效果评价奠定基础,为促进学生自主学习、教学持续改进提供支撑。 展开更多
关键词 平台型医学课程 在线教学 学习效果 评价指标 评价标准
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双歧杆菌联合维生素K1治疗黄疸患儿的疗效及其对炎症指标的影响
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作者 王静 吴项英 强中洋 《川北医学院学报》 CAS 2024年第6期754-757,共4页
目的:探讨双歧杆菌联合维生素K1治疗黄疸患儿的疗效及对其炎症指标的影响。方法:将102例黄疸患儿按照治疗方式不同分为对照组和试验组,每组各51例。对照组患儿给予常规治疗和维生素K1治疗;试验组患儿在对照组的基础上给予双歧杆菌治疗... 目的:探讨双歧杆菌联合维生素K1治疗黄疸患儿的疗效及对其炎症指标的影响。方法:将102例黄疸患儿按照治疗方式不同分为对照组和试验组,每组各51例。对照组患儿给予常规治疗和维生素K1治疗;试验组患儿在对照组的基础上给予双歧杆菌治疗。比较两组患儿的临床指标、疗效、黄疸指数、炎症指标及不良反应发生情况。结果:试验组患儿胎便排空、黄疸消退及住院时间均短于对照组(P<0.05),排便次数高于对照组(P<0.05)。试验组治疗总有效率高于对照组(P<0.05)。治疗后,两组患儿黄疸指数、白细胞介素6(IL-6)、C反应蛋白(CRP)及降钙素原(PCT)水平均降低(P<0.05),且试验组低于对照组(P<0.05)。两组患儿不良反应发生率无统计学差异(P>0.05)。结论:双歧杆菌联合维生素K1治疗黄疸的疗效较显著,且在改善患儿临床症状及炎症反应方面效果较好,治疗安全性高,可为临床治疗黄疸患儿提供借鉴。 展开更多
关键词 黄疸 新生儿 双歧杆菌 维生素K1 疗效 炎症指标
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海外受众媒介接触行为对武术文化传播效果影响的实证研究
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作者 辛双双 马秀杰 《成都体育学院学报》 北大核心 2024年第2期59-66,共8页
文章在构建微观武术国际化传播效果研究框架的基础上合成传播效果综合指数。采用武术信息接触月频次、武术信息接触时间与媒介接触种类数等几个维度作为媒介接触行为概念,借助调节效应模型探讨媒介接触行为对不同教育程度海外受众的武... 文章在构建微观武术国际化传播效果研究框架的基础上合成传播效果综合指数。采用武术信息接触月频次、武术信息接触时间与媒介接触种类数等几个维度作为媒介接触行为概念,借助调节效应模型探讨媒介接触行为对不同教育程度海外受众的武术传播效果的影响。研究结果显示,4个媒介接触行为指标均与传播效果存在正相关,并且武术信息接触时间、传统媒介接触类型数与网络新媒介接触类型数相对于武术信息接触月频次对不同教育程度群体的武术传播效果调节效应要显著,武术传播效果的影响因素是复杂多元的,媒介接触行为有待于后续研究在这一领域继续探索。 展开更多
关键词 媒介接触 传播效果 武术文化 综合指数
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