期刊文献+
共找到6,249篇文章
< 1 2 250 >
每页显示 20 50 100
Tanshinone IIA ameliorates energy metabolism dysfunction of pulmonary fibrosis using 13C metabolic flux analysis
1
作者 Baixi Shan Haoyan Zhou +4 位作者 Congying Guo Xiaolu Liu Mingyu Wu Rao Zhai Jun Chen 《Journal of Pharmaceutical Analysis》 SCIE CAS CSCD 2024年第2期244-258,共15页
Evidence indicates that metabolic reprogramming characterized by the changes in cellular metabolic patterns contributes to the pathogenesis of pulmonary fibrosis (PF). It is considered as a promising therapeutic targe... Evidence indicates that metabolic reprogramming characterized by the changes in cellular metabolic patterns contributes to the pathogenesis of pulmonary fibrosis (PF). It is considered as a promising therapeutic target anti-PF. The well-documented against PF properties of Tanshinone IIA (Tan IIA) have been primarily attributed to its antioxidant and anti-inflammatory potency. Emerging evidence suggests that Tan IIA may target energy metabolism pathways, including glycolysis and tricarboxylic acid (TCA) cycle. However, the detailed and advanced mechanisms underlying the anti-PF activities remain obscure. In this study, we applied [U-13C]-glucose metabolic flux analysis (MFA) to examine metabolism flux disruption and modulation nodes of Tan IIA in PF. We identified that Tan IIA inhibited the glycolysis and TCA flux, thereby suppressing the production of transforming growth factor-β1 (TGF-β1)-dependent extracellular matrix and the differentiation and proliferation of myofibroblasts in vitro. We further revealed that Tan IIA inhibited the expression of key metabolic enzyme hexokinase 2 (HK2) by inhibiting phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR)/hypoxia-inducible factor 1α (HIF-1α) pathway activities, which decreased the accumulation of abnormal metabolites. Notably, we demonstrated that Tan IIA inhibited ATP citrate lyase (ACLY) activity, which reduced the collagen synthesis pathway caused by cytosol citrate consumption. Further, these results were validated in a mouse model of bleomycin-induced PF. This study was novel in exploring the mechanism of the occurrence and development of Tan IIA in treating PF using 13C-MFA technology. It provided a novel understanding of the mechanism of Tan IIA against PF from the perspective of metabolic reprogramming. 展开更多
关键词 Pulmonary fibrosis Tanshinone IIA 13C-metabolic flux analysis Metabolic reprogramming
下载PDF
Impact of primary percutaneous coronary intervention on ST-segment elevation myocardial infarction patients:A comprehensive analysis
2
作者 Eza Nawzad Saeed Abdulsatar Kamil Faeq 《World Journal of Experimental Medicine》 2024年第1期58-69,共12页
BACKGROUND Myocardial infarction,particularly ST-segment elevation myocardial infarction(STEMI),is a key global mortality cause.Our study investigated predictors of mortality in 96 STEMI patients undergoing primary pe... BACKGROUND Myocardial infarction,particularly ST-segment elevation myocardial infarction(STEMI),is a key global mortality cause.Our study investigated predictors of mortality in 96 STEMI patients undergoing primary percutaneous coronary intervention at Erbil Cardiac Center.Multiple factors were identified influencing in-hospital mortality.Significantly,time from symptom onset to hospital arrival emerged as a decisive factor.Consequently,our study hypothesis is:"Reducing time from symptom onset to hospital arrival significantly improves STEMI prognosis."AIM To determine the key factors influencing mortality rates in STEMI patients.METHODS We studied 96 consecutive STEMI patients undergoing primary percutaneous coronary intervention(PPCI)at the Erbil Cardiac Center.Their clinical histories were compiled,and coronary evaluations were performed via angiography on admission.Data included comorbid conditions,onset of cardiogenic shock,complications during PPCI,and more.Post-discharge,one-month follow-up assessments were completed.Statistical significance was set at P<0.05.RESULTS Our results unearthed several significant findings.The in-hospital and 30-d mortality rates among the 96 STEMI patients were 11.2%and 2.3%respectively.On the investigation of independent predictors of in-hospital mortality,we identified atypical presentation,onset of cardiogenic shock,presence of chronic kidney disease,Thrombolysis In Myocardial Infarction grades 0/1/2,triple vessel disease,ventricular tachycardia/ventricular fibrillation,coronary dissection,and the no-reflow phenomenon.Specifically,the recorded average time from symptom onset to hospital arrival amongst patients who did not survive was significantly longer(6.92±3.86 h)compared to those who survived(3.61±1.67 h),P<0.001.These findings underscore the critical role of timely intervention in improving the survival outcomes of STEMI patients.CONCLUSION Our results affirm that early hospital arrival after symptom onset significantly improves survival rates in STEMI patients,highlighting the critical need for prompt intervention. 展开更多
关键词 Percutaneous coronary intervention impact analysis Segment elevation Erbil
下载PDF
Energy Transfer Mechanism and Probability Analysis of Submarine Pipe Laterally Impacted by Dropped Objects 被引量:3
3
作者 梁静 余建星 +3 位作者 余杨 W.Lam 赵羿羽 段晶辉 《China Ocean Engineering》 SCIE EI CSCD 2016年第3期319-328,共10页
Energy transfer ratio is the basic-factor affecting the level of pipe damage during the impact between dropped object and submarine pipe. For the purpose of studying energy transfer and damage mechanism of submarine p... Energy transfer ratio is the basic-factor affecting the level of pipe damage during the impact between dropped object and submarine pipe. For the purpose of studying energy transfer and damage mechanism of submarine pipe impacted by dropped objects, series of experiments are designed and carried out. The effective yield strength is deduced to make the quasi-static analysis more reliable, and the normal distribution of energy transfer ratio caused by lateral impact on pipes is presented by statistic analysis of experimental results based on the effective yield strength, which provides experimental and theoretical basis for the risk analysis of submarine pipe system impacted by dropped objects. Failure strains of pipe material are confirmed by comparing experimental results with finite element simulation. In addition, impact contact area and impact time are proved to be the major influence factors of energy transfer by sensitivity analysis of the finite element simulation. 展开更多
关键词 impact PIPE energy transfer quasi-static analysis FE simulation
下载PDF
Analysis of hydrogeolgical characteristics and water environmental impact pathway of typical shale gas exploration and development zones in Sichuan Basin, China 被引量:5
4
作者 SUN Dong LIU Xin-ze +4 位作者 YANG Hai-jun CAO Nan ZHANG Zhi-peng CHEN Yin-song LI Da-meng 《Journal of Groundwater Science and Engineering》 2019年第3期195-213,共19页
Studying the influence of shale gas exploration and development on groundwater environment is the basis of guiding water environment protection in the process of shale gas exploration and development.Groundwater envir... Studying the influence of shale gas exploration and development on groundwater environment is the basis of guiding water environment protection in the process of shale gas exploration and development.Groundwater environmental pollution is concealed,complex and persistent.Once it is difficult to control the pollution,the current commercial shale gas development zones in Sichuan Basin that are mostly located in karst areas and highly sensitive to groundwater will be vulnerable to the impact of shale gas exploration and development.Based on the hydrogeological conditions of shale gas exploration and development area and combined with engineering analysis of exploration and development,various risk pathways that may affect the groundwater environment during process of shale gas exploration,mining well construction,mining operations and other stages were identified in this paper.Some existing risk pathways were proved by verification of typical areas and should not be ignored.Based on the actual situation of typical areas,the countermeasures of groundwater environmental protection in the process of shale gas exploration and development in karst areas were discussed.It is believed that the groundwater environment can be better protected by strengthening administration,research and application of new technologies,precise design,hydrogeological conditions,and research and feedback of groundwater environmental protection. 展开更多
关键词 Groundwater environment SHALE gas impact PATHWAY analysis
下载PDF
Analysis of the Impact of Climate Change on the Phenology of Animals
5
作者 翟贵明 李振国 王明涛 《Meteorological and Environmental Research》 CAS 2010年第5期102-105,110,共5页
Using linear regression and correlation analysis method,the variation trend characteristics of average temperature,sunshine,precipitation and the phenology of five kinds of animals(Barn Swallows,Frogs,Cryptotympana at... Using linear regression and correlation analysis method,the variation trend characteristics of average temperature,sunshine,precipitation and the phenology of five kinds of animals(Barn Swallows,Frogs,Cryptotympana atra,Crickets,Indian Cuckoo) in Huimin County during 1980-2008 were analyzed.On this basis,the relationship between the phenological phases of various animals and monthly temperature,sunshine and precipitation was analyzed.And the reasons that the phenological phases of various animals adapted to the climatic factors were also discussed. 展开更多
关键词 CLIMATE PHENOLOGY ANIMALS impact analysis China
下载PDF
Numerical and experimental analysis of the closed-cell aluminium foam under low velocity impact using computerized tomography technique 被引量:3
6
作者 S.Talebi M.Sadighi M.M.Aghdam 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2019年第1期144-155,I0005,共13页
In the present work, the response of closed-cell aluminum foams under low-velocity impact has been studied numerically and experimentally. Computerized tomography is employed to access three-dimensional (3D) microstru... In the present work, the response of closed-cell aluminum foams under low-velocity impact has been studied numerically and experimentally. Computerized tomography is employed to access three-dimensional (3D) microstructure of the closed-cell aluminum foam. Effective parameters including foam density and the velocity of impactor on foam dynamic behavior are investigated. In order to show the validity and accuracy of results, some static experiments and low-velocity impact tests have been conducted. Results in dicate a remarkable agree me nt between the simulation and experimental data. Moreover, the results show that by increasing the density of foam samples, the highest difference between numerical and experimenidi results for peak stress and absorbed energy are 35.9% and 6.9%, respectively, which is related to the highest density. For impact velocities ranging from 3.1 to 4.2 m/s, the maximum discrepancy in peak stress and absorbed energy occur at an inipact velocity of 3.1 m/s in which corresponding errors are 33.3% and 6.6%, respectively. For the impact velocity of 40 m/s, the highest increase in peak stress and absorbed energy are 667.9% and 370.3% associated with the density of 0.5 and 0.3 g/cm^3, respectively. 展开更多
关键词 FINITE ELEMENT analysis impact Aluminum foam Experimental analysis Energy ABSORPTION
下载PDF
Dynamic impact experiment and response characteristics analysis for 1:2 reduced-scale model of hydraulic support 被引量:5
7
作者 Huaiwei Ren Desheng Zhang +4 位作者 Shixin Gong Kai Zhou Chenyang Xi Ming He Tijian Li 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2021年第3期347-356,共10页
It is significant to research the impact resistance properties of hydraulic support due to its key support role in the fully mechanized mining face.However,it is difficult for the entire hydraulic support to implement... It is significant to research the impact resistance properties of hydraulic support due to its key support role in the fully mechanized mining face.However,it is difficult for the entire hydraulic support to implement the impact experiment underground and analyze the response characteristic.Therefore,a dynamic impact experiment for the entire hydraulic support was proposed in this paper,where a 1:2 reducedscale model of hydraulic support was designed and its response characteristics under dynamic impact load were analyzed.Firstly,a comprehensive monitoring scheme was proposed to achieve an effective monitoring for dynamic response of hydraulic support.Secondly,a multi-scale impact experiment was carried out for the entire hydraulic support and dynamic behaviors of hydraulic support under the multi-scale impact load were revealed by experimental data.Then a dynamic impact experiment of the entire hydraulic support was simulated in ADAMS with the same experiment conditions,and the experimental and simulation data were verified mutually.Finally,the characteristics of energy conversion and dissipation of the entire experiment system after impact were analyzed.The experiment results showed that the impact resistance properties of hydraulic support largely depended on the initial support conditions and different vertical rigidities affected energy distribution proportion of the entire support system. 展开更多
关键词 Hydraulic support impact experiment Characteristics analysis Dynamics simulation ADAMS
下载PDF
Calculation of Ecological Footprint Based on Modified Method and Quantitative Analysis of Its Impact Factors——A Case Study of Shanghai 被引量:4
8
作者 GAO Chengkang JIANG Dahe +1 位作者 WANG Dan YAN Jonathan 《Chinese Geographical Science》 SCIE CSCD 2006年第4期306-313,共8页
Ecological footprint (EF) has attracted much attention internationally as a potential indicator for sustainable development. In China, EF has also gained recognition in related fields and disciplines. Moreover, some... Ecological footprint (EF) has attracted much attention internationally as a potential indicator for sustainable development. In China, EF has also gained recognition in related fields and disciplines. Moreover, some scholars in these fields have proposed alternative methods to calculate EF and have made some progress. This paper, therefore, begins with the introduction and development of EF in China. However, the established methods of EF calculation hold some limitations, such as indicator variance and result abnormality. In order to resolve those problems, the authors make a further modification considering the demand of EF as a comprehensive indicator: 1) More accurate analysis has been done to divide EF into several parts: imported EF, exported EF, and producible EF, which is the solution to the problem of abnormality in original EF results and can explain abnormal phenomena reasonably. 2) Considering the actual situa- tion of Shanghai, emended equivalence factor is brought forward and a matrix is formed with equivalence factors. The measure can reduce the deviation between the fact and the results. 3) The calculation compares local yield with global average yield to analyze the effects of yields. And based on local yields in different years, the results are more accurate. Finally, the calculation method is applied to calculating EF of Shanghai from 1980 to 2003, and the subsequent detailed analysis is presented. Available data and results suggest a statistically significant correlation coefficient between EF and GDP, population density and urbaniTation level. Through analyzing the process of calculating EF and its results, it can be seen that EF, as a macro-indicator, can not exactly indicate whether development within a region can meet the re- quests of sustainable development, which can be explained by the fact that the result of EF is impacted greatly by sub- jective factors including national policy,available technology, population, etc. Nevertheless, EF can demonstrate, at least to some degree, the regional status in terms of resources and energy consumption, as well as developmental potential. The calculation of EF, therefore, deserves further research to achieve more far-reaching significance in application. 展开更多
关键词 ecological footprint quantitative analysis impact factors SHANGHAI
下载PDF
Numerical Analysis of Hydrodynamic Pressure Induced by Fluid-Solid Impact 被引量:2
9
作者 黄玉盈 邹时智 +1 位作者 钱勤 李其申 《China Ocean Engineering》 SCIE EI 2000年第1期1-13,共13页
As a further development of the authors' work (Huang and Qian, 1993), in this paper a new numerical method based on the time domain boundary element technique is proposed for solving fluid-solid coupling problems,... As a further development of the authors' work (Huang and Qian, 1993), in this paper a new numerical method based on the time domain boundary element technique is proposed for solving fluid-solid coupling problems, in which a rigid body impacts normally on the calm surface of a half-space fluid. A fundamental solution to the half-space potential flow problem is first derived with the method of images. Then, an equivalent boundary integral equation in the Laplace transform domain is established by means of Green's second identity. Through the inverse Laplace transform and discretization in both time and boundary of the fluid region, the numerical calculation for the problem under consideration has been carried out. Several examples demonstrate that the present method is more efficient than existing ones, from which it is also seen that the shape of the impacting body has a considerable effect on the total impact force. 展开更多
关键词 fluid-solid impact boundary element method hydrodynamic pressure potential flow numerical analysis
下载PDF
Methods for Progressive Collapse Analysis of Building Structures Under Blast and Impact Loads 被引量:5
10
作者 李忠献 师燕超 《Transactions of Tianjin University》 EI CAS 2008年第5期329-339,共11页
Progressive collapse of building structures under blast and impact loads has attracted great attention all over the world. Progressive collapse analysis is essential for an economic and safe design of building structu... Progressive collapse of building structures under blast and impact loads has attracted great attention all over the world. Progressive collapse analysis is essential for an economic and safe design of building structures against progressive collapse to blast and impact loads. Because of the catastrophic nature of progressive collapse and the potentially high cost of constructing or retrofitting buildings to resist it, it is imperative that the progressive collapse analysis methods be reliable. For engineers, their methodology to carry out progressive collapse evaluation need not only be accurate and concise, but also be easily used and works fast. Thus, many researchers have been spending lots of effort in developing reliable, efficient and straightforward progressive collapse analysis methods recently. In the present paper, current progressive collapse analysis methods available in the literature are reviewed. Their suitability, applicability and reliability are discussed. Our recent proposed new method for progressive collapse analysis of reinforced concrete frames under blast loads is also introduced. 展开更多
关键词 progressive collapse analysis building structures blast load impact load
下载PDF
A Case Study of Impact of FY-2C Satellite Data in Cloud Analysis to Improve Short-Range Precipitation Forecast 被引量:6
11
作者 LIU Rui-Xia CHEN Hong-Bin +1 位作者 CHEN De-Hui XU Guo-Qiang 《Atmospheric and Oceanic Science Letters》 CSCD 2014年第6期527-533,共7页
Chinese FengYun-2C(FY-2C) satellite data were combined into the Local Analysis and Prediction System(LAPS) model to obtain three-dimensional cloud parameters and rain content. These parameters analyzed by LAPS were us... Chinese FengYun-2C(FY-2C) satellite data were combined into the Local Analysis and Prediction System(LAPS) model to obtain three-dimensional cloud parameters and rain content. These parameters analyzed by LAPS were used to initialize the Global/Regional Assimilation and Prediction System model(GRAPES) in China to predict precipitation in a rainstorm case in the country. Three prediction experiments were conducted and were used to investigate the impacts of FY-2C satellite data on cloud analysis of LAPS and on short range precipitation forecasts. In the first experiment, the initial cloud fields was zero value. In the second, the initial cloud fields were cloud liquid water, cloud ice, and rain content derived from LAPS without combining the satellite data. In the third experiment, the initial cloud fields were cloud liquid water, cloud ice, and rain content derived from LAPS including satellite data. The results indicated that the FY-2C satellite data combination in LAPS can show more realistic cloud distributions, and the model simulation for precipitation in 1–6 h had certain improvements over that when satellite data and complex cloud analysis were not applied. 展开更多
关键词 FY-2C satellite data cloud analysis precipitation forecast impact study
下载PDF
A 3-D DDA damage analysis of brick masonry buildings under the impact of boulders in mountainous areas 被引量:3
12
作者 LIU Shu-guang LI Zhu-jun +3 位作者 ZHANG Hong WU Wei ZHONG Gui-hui LOU Sha 《Journal of Mountain Science》 SCIE CSCD 2018年第3期657-671,共15页
In mountainous areas, geological disasters carrying large boulders can cause severe damage to the widely used masonry buildings due to the high impact forces. To better understand the damage of brick masonry buildings... In mountainous areas, geological disasters carrying large boulders can cause severe damage to the widely used masonry buildings due to the high impact forces. To better understand the damage of brick masonry buildings under the impact of boulders, a "block-joint" model is developed using threedimensional discontinuous deformation analysis(3-D DDA) to simulate the behaviour of the "brick-mortar" structure. The "block-joint" model is used to capture not only the large displacement and deformation of individual bricks but also the large-scale sliding and opening along the mortar between the bricks. The linear elastic constitutive model is applied to account for the non-plastic deformation behaviour of brick materials. Furthermore, the mechanical characteristics of the mortar are represented using the Mohr-Coulomb and Drucker-Prager criteria. To propose safe structural design schemes and effective reinforcement for brick masonry buildings, seven construction techniques are considered, includingdifferent grades of brick and mortar, effective shear areas and reinforced members. The proposed 3-D DDA model is used to analyse the velocity distribution and the key point displacements of the brick masonry building under the impact of boulders. The results show that upgrading the brick and mortar, increasing the wall thickness, making full use of the wall thickness, and adding a circular beam and structural column are very effective approaches for improving the impact resistance of brick masonry buildings. 展开更多
关键词 Damage analysis Brick masonry building Boulder impact Brick-mortar structure Block-joint model Discontinuous deformation analysis
下载PDF
An efficient formulation based on the Lagrangian method for contact–impact analysis of flexible multi-body system 被引量:7
13
作者 Peng Chen Jin-Yang Liu Jia-Zhen Hong 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2016年第2期326-334,共9页
In this paper,an efficien formulation based on the Lagrangian method is presented to investigate the contact–impact problems of f exible multi-body systems.Generally,the penalty method and the Hertz contact law are t... In this paper,an efficien formulation based on the Lagrangian method is presented to investigate the contact–impact problems of f exible multi-body systems.Generally,the penalty method and the Hertz contact law are the most commonly used methods in engineering applications.However,these methods are highly dependent on various non-physical parameters,which have great effects on the simulation results.Moreover,a tremendous number of degrees of freedom in the contact–impact problems will influenc thenumericalefficien ysignificantl.Withtheconsideration of these two problems,a formulation combining the component mode synthesis method and the Lagrangian method is presented to investigate the contact–impact problems in fl xible multi-body system numerically.Meanwhile,the finit element meshing laws of the contact bodies will be studied preliminarily.A numerical example with experimental verificatio will certify the reliability of the presented formulationincontact–impactanalysis.Furthermore,aseries of numerical investigations explain how great the influenc of the finit element meshing has on the simulation results.Finally the limitations of the element size in different regions are summarized to satisfy both the accuracy and efficien y. 展开更多
关键词 Multi-body dynamics Contact–impact analysis Lagrangian method Component mode synthesis
下载PDF
Cost effectiveness analysis of population-based serology screening and ^(13)C-Urea breath test for Helicobacter pylori to prevent gastric cancer:A markov model 被引量:4
14
作者 Feng Xie Nan Luo Hin-Peng Lee 《World Journal of Gastroenterology》 SCIE CAS CSCD 2008年第19期3021-3027,共7页
AIM:To compare the costs and effectiveness of no screening and no eradication therapy, the population- based Helicobacter pylori (H pylori) serology screening with eradication therapy and 13C-Urea breath test (UBT) wi... AIM:To compare the costs and effectiveness of no screening and no eradication therapy, the population- based Helicobacter pylori (H pylori) serology screening with eradication therapy and 13C-Urea breath test (UBT) with eradication therapy. METHODS:A Markov model simulation was carried out in all 237 900 Chinese males with age between 35 and 44 from the perspective of the public healthcare provider in Singapore. The main outcome measures were the costs, number of gastric cancer cases prevented, life years saved, and quality-adjusted life years (QALYs) gained from screening age to death. The uncertainty surrounding the cost-effectiveness ratio was addressed by one-way sensitivity analyses. RESULTS:Compared to no screening, the incremental cost-effectiveness ratio (ICER) was $16 166 per life year saved or $13 571 per QALY gained for the serology screening, and $38 792 per life year saved and $32 525 per QALY gained for the UBT. The ICER was $477 079 per life year saved or $390 337 per QALY gained for the UBT compared to the serology screening. The cost- effectiveness of serology screening over the UBT was robust to most parameters in the model. CONCLUSION:The population-based serologyscreening for H pylori was more cost-effective than the UBT in prevention of gastric cancer in Singapore Chinese males. 展开更多
关键词 Cost-effectiveness analysis Gastric cancer He/icobacterpy/ori 13C-Urea breath test SEROLOGY
下载PDF
模拟增温对植物叶片δ^(13)C值的影响:全球Meta分析
15
作者 张莉莉 叶志成 +3 位作者 廖凯华 朱青 赖晓明 郭长强 《生态学报》 CAS CSCD 北大核心 2024年第12期5412-5421,共10页
温室气体大量排放导致的全球变暖是最为关注的环境问题之一,这会直接影响植物的生长与发育进而影响群落组成乃至生态系统的结构和功能。水分利用效率作为植物叶片通过光合作用调节水分生理过程的指标,是联系生态系统碳循环与水循环关系... 温室气体大量排放导致的全球变暖是最为关注的环境问题之一,这会直接影响植物的生长与发育进而影响群落组成乃至生态系统的结构和功能。水分利用效率作为植物叶片通过光合作用调节水分生理过程的指标,是联系生态系统碳循环与水循环关系的关键,反映了植被生态系统对立地环境快速调整和资源变化的适应策略,是当前全球变化研究中的重点。植物叶片碳稳定同位素比值(δ^(13)C)是反映植物长期水分利用效率的关键指标,但全球气候变暖对植物叶片δ^(13)C值的影响仍存在较大争议。该研究利用Meta分析整合全球范围内51份相关研究文献中的371组数据,较为系统地评估模拟增温对植物叶片δ^(13)C及其生理生态指标的影响。结果表明,模拟增温能够使叶片δ^(13)C值显著升高0.6%(P<0.001),同时对叶片呼吸速率R_(d)、气孔导度G_(s)、净光合作用速率P_(n)、碳C的效应值分别为0.237、0.062、-0.140、-0.019 (P<0.05)。模拟增温处理在增强植物光合作用的同时提高了叶片呼吸速率(R_(d)),导致光合产物不断被消耗、叶片碳(C)降低,最终使叶片P_(n)降低并且叶片δ^(13)C产生富集现象。通过进一步对影响因素分析发现,叶片δ^(13)C值对增温的响应主要受增温时间、高程和年均气温等控制(相对重要性指数分别为1.00、0.97和0.92)。另外,模拟增温时选用不同的增温模式对叶片δ^(13)C值也具有显著不同的影响,采用红外线加热、土柱置换和电缆增温等方法对叶片δ^(13)C值具有正向促进作用(效应值分别为0.70、0.44和0.35),而采用遮阳屏与开顶箱增温等方法具有负向作用(效应值分别为-0.17和-0.09)。研究结论对于深入理解全球变化背景下植物水分利用的响应特征具有重要的理论意义,以期为今后该领域的植物生长研究提供理论依据和有效支撑。 展开更多
关键词 模拟增温 叶片δ^(13)C META分析 气孔导度 呼吸速率 植物水分利用效率
下载PDF
Analysis on the Impact of Facility Agriculture Development on Climate Change in Weifang 被引量:1
16
作者 XIAO Qing-hua LI Shu-jun +1 位作者 CUI Jian-yun YUAN Jing 《Meteorological and Environmental Research》 CAS 2011年第6期55-60,共6页
[Objective] The research aimed to study the influence of facility agriculture development on the climate variation in Weifang. [Method] Shouguang was selected as the representative station of greenhouse shed planting ... [Objective] The research aimed to study the influence of facility agriculture development on the climate variation in Weifang. [Method] Shouguang was selected as the representative station of greenhouse shed planting zone. By using the precipitation, temperature and relative humidity, etc. in Weifang City during 1961-2010, the climatic variation situations in the whole city and the greenhouse shed planting zone were analyzed. The variation trend and evolution characteristics of climate in the different seasons before and after the facility agriculture plantation were contrasted and analyzed. [Result] The annual rainfall and relative humidity presented the declining trend in the whole city in recent 50 years. The annual average, maximum and minimum temperatures all presented the rising trend. Since the large-scale plantation of greenhouse shed, the declining range of annual rainfall in the greenhouse shed planting zone was lower than that in the whole city, and the declining range of relative humidity was obviously higher than that in the whole city. The rising ranges of annual average, maximum and minimum temperatures were higher than that in the whole city. [Conclusion] The research provided the theory basis for the development of facility agriculture. 展开更多
关键词 Facility agriculture Climate change impact analysis China
下载PDF
Impact analysis of casting parts considering shrinkage cavity defect 被引量:1
17
作者 Si-Young Kwak Jie Cheng Jeong-Kil Choi 《China Foundry》 SCIE CAS 2011年第1期112-116,共5页
Shrinkage cavity may be detrimental to mechanical performances of casting parts.As a consequence,design engineers often use overly large safety factors in many designs due to insufficient understanding of quantitative... Shrinkage cavity may be detrimental to mechanical performances of casting parts.As a consequence,design engineers often use overly large safety factors in many designs due to insufficient understanding of quantitative effects of shrinkage cavity defects.In this paper,process of Al alloy wheel impact test was computationally analyzed for both the wheel models with and without shrinkage cavity defects.Based on shrinkage cavity data obtained from industrial CT (Computerized Tomography),the shrinkage cavity defects were modeled with SSM (Shape Simplification Method),which reconstructs shrinkage cavity defects to hollow spheroid primitives.After the impact simulation was conducted,the results show that under impact test condition,the wheel considering shrinkage cavity defects may fracture while the sound-assumed wheel may not. 展开更多
关键词 CASTING shrinkage cavity defect impact computational analysis Al alloy wheel
下载PDF
Prognostic impact of the red cell distribution width in esophageal cancer patients: A systematic review and meta-analysis 被引量:11
18
作者 Wei-Yu Xu Xiao-Bo Yang +8 位作者 Wen-Qin Wang Yi Bai Jun-Yu Long Jian-Zhen Lin Jian-Ping Xiong Yong-Chang Zheng Xiao-Dong He Hai-Tao Zhao Xin-Ting Sang 《World Journal of Gastroenterology》 SCIE CAS 2018年第19期2120-2129,共10页
AIM To clarify the previous discrepant conclusions, we performed a meta-analysis to evaluate the prognostic value of red cell distribution width(RDW) in esophageal cancer(EC). METHODS We searched the PubM ed, EMBASE, ... AIM To clarify the previous discrepant conclusions, we performed a meta-analysis to evaluate the prognostic value of red cell distribution width(RDW) in esophageal cancer(EC). METHODS We searched the PubM ed, EMBASE, Web of Science and Cochrane Library databases to identify clinical studies, followed by using STATA version 12.0 for statistical analysis. Studies that met the following criteria were considered eligible:(1) Studies including EC patients who underwent radical esophagectomy;(2) studies including patients with localized disease without distant metastasis;(3) studies including patients without preoperative neoadjuvant therapy;(4) studies including patients without previous antiinflammatory therapies and with available preoperative laboratory outcomes;(5) studies reporting association between the preoperative RDW and overall survival(OS)/disease-free survival(DFS)/cancer-specific survival(CSS); and(6) studies published in English.RESULTS A total of six articles, published between 2015 and 2017, fulfilled the selection criteria in the end. Statistical analysis showed that RDW was not associated with the prognosis of EC patients, irrespective of OS/CSS [hazard ratio(HR) = 1.27, 95% confidence interval(CI): 0.97-1.57, P = 0.000] or DFS(HR = 1.42, 95%CI: 0.96-1.88, P = 0.000). Subgroup analysis indicated that elevated RDW was significantly associated with worse OS/CSS of EC patients when RDW > 13%(HR = 1.45, 95%CI: 1.13-1.76, P = 0.000), when the patient number ≤ 400(HR = 1.45, 95%CI: 1.13-1.76, P = 0.000) and when the study type was retrospective(HR = 1.42, 95%CI : 1.16-1.69, P = 0.000).CONCLUSION Contrary to our general understanding, this meta-analysis revealed that RDW cannot serve as an indicator of poor prognosis in patients with EC. However, it may still be a useful predictor of unfavorable prognosis using an appropriate cut-off value. 展开更多
关键词 RED cell distribution WIDTH PROGNOSTIC impact Systematic review META-analysis
下载PDF
Analysis of tritium production in a 2 MW liquid-fueled molten salt experimental reactor and its environmental impact 被引量:2
19
作者 Xiao-Wen Lyu Xiao-BinXia +2 位作者 Zhi-Hong Zhang Jun Cai Chang-Qi Chen 《Nuclear Science and Techniques》 SCIE CAS CSCD 2016年第4期7-13,共7页
Tritium release is one of the most concerning topics in nuclear power plants. Here, the tritium production in a 2 MW liquid-fueled molten salt experimental reactor(TMSR-LF1) was calculated by ORIGEN-S with an updated ... Tritium release is one of the most concerning topics in nuclear power plants. Here, the tritium production in a 2 MW liquid-fueled molten salt experimental reactor(TMSR-LF1) was calculated by ORIGEN-S with an updated cross-section library generated by TRITON in SCALE 6.1.3 code system. The results show that the tritium production rate and normalized tritium production rate of TMSR-LF1 are 8.90x10^(11)Bq/day and4.45x10^(11)Bq/(MW day), respectively. The environmental impact of tritium was analyzed via PC-CREAM 08 with an assumed 36 % release rate of tritium referring to the molten salt reactor experiment. During normal operations, the maximum tritium concentration is 1.4 Bq/m^3 under normal condition, and the corresponding individual dose to the public is about 1 μSv/a; under extreme conditions, the maximum concentration and corresponding individual doses are 11.8 Bq/m^3 and 9 μSv/a, respectively.Ingestion is the main exposure pathway and accounts for62 % of the total dose. Of this, 35 % is from organically bound tritium. 展开更多
关键词 氚浓度 生产分析 液体燃料 环境影响 熔盐 实验堆 实验反应堆 TRITON
下载PDF
Dynamic impact properties of deep sandstone under thermal-hydraulicmechanical coupling loads
20
作者 CAO Chunhui DING Haonan ZOU Baoping 《Journal of Mountain Science》 SCIE CSCD 2024年第6期2113-2129,共17页
The deep rock mass within coal mines situated in a challenging environment are characterized by high ground stress,high geotemperature,high osmotic water pressure,and dynamic disturbances from mechanical excavation.To... The deep rock mass within coal mines situated in a challenging environment are characterized by high ground stress,high geotemperature,high osmotic water pressure,and dynamic disturbances from mechanical excavation.To investigate the impact of this complex mechanical environment on the dynamic characteristics of roof sandstone in self-formed roadways without coal pillars,standard specimens of deep sandstone from the 2611 upper tunnel working face of the Yongmei Company within the Henan Coal Chemical Industry Group in Henan,China were prepared,and an orthogonal test was designed.Using a self-developed geotechnical dynamic impact mechanics test system,triaxial dynamic impact tests under thermal-hydraulicmechanical coupling conditions were conducted on deep sandstone.The results indicate that under high confining pressure,deep sandstone exhibits pronounced brittle failure at low temperatures,with peak strength gradually decreasing as temperature and osmotic water pressure increase.Conversely,under low confining pressure and low temperature,the brittleness of deep sandstone weakens gradually,while ductility increases.Moreover,sandstone demonstrates higher peak strength at low temperatures under high axial pressure conditions,lower peak strength at high temperatures,and greater strain under low axial pressure and high osmotic water pressure.Increases in impact air pressure and osmotic water pressure have proportionally greater effects on peak stress and peak strain.Approximately 50%of the input strain energy is utilized as effective energy driving the sandstone fracture process.Polar analysis identifies the optimal combination of factors affecting the peak stress and peak strain of sandstone.Under the coupling effect,intergranular and transgranular fractures occur within the sandstone.SEM images illustrate that the damage forms range from minor damage with multiple fissures to extensive fractures and severe fragmentation.This study elucidates the varied dynamic impact mechanical properties of deep sandstones under thermal-hydraulic-mechanical coupling,along with multifactor analysis methods and their optimal factor combinations. 展开更多
关键词 Deep sandstone Thermal-hydraulicmechanical coupling Dynamic impact STRESS-STRAIN Failure Modes Polar analysis
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部