期刊文献+
共找到1,373篇文章
< 1 2 69 >
每页显示 20 50 100
Grain Yield,Biomass Accumulation,and Leaf Photosynthetic Characteristics of Rice under Combined Salinity-Drought Stress
1
作者 WEI Huanhe GENG Xiaoyu +7 位作者 ZHANG Xiang ZHU Wang ZHANG Xubin CHEN Yinglong HUO Zhongyang ZHOU Guisheng MENG Tianyao DAI Qigen 《Rice science》 SCIE CSCD 2024年第1期118-128,I0023,共12页
Simultaneous stresses of salinity and drought often coincide during rice-growing seasons in saline lands,primarily due to insufficient water resources and inadequate irrigation facilities.Consequently,combined salinit... Simultaneous stresses of salinity and drought often coincide during rice-growing seasons in saline lands,primarily due to insufficient water resources and inadequate irrigation facilities.Consequently,combined salinity-drought stress poses a major threat to rice production.In this study,two salinity levels(NS,non-salinity;HS,high salinity)along with three drought treatments(CC,control condition;DJ,drought stress imposed at jointing;DH,drought stress imposed at heading)were performed to investigate their combined influences on leaf photosynthetic characteristics,biomass accumulation,and rice yield formation.Salinity,drought,and their combination led to a shortened growth period from heading to maturity,resulting in a reduced overall growth duration.Grain yield was reduced under both salinity and drought stress,with a more substantial reduction under the combined salinity-drought stress.The combined stress imposed at heading caused greater yield losses in rice compared with the stress imposed at jointing.Additionally,the combined salinity-drought stress induced greater decreases in shoot biomass accumulation from heading to maturity,as well as in shoot biomass and nonstructural carbohydrate(NSC)content in the stem at heading and maturity.However,it increased the harvest index and NSC remobilization reserve.Salinity and drought reduced the leaf area index and SPAD value of flag leaves and weakened the leaf photosynthetic characteristics as indicated by lower photosynthetic rates,transpiration rates,and stomatal conductance.These reductions were more pronounced under the combined stress.Salinity,drought,and especially their combination,decreased the activities of ascorbate peroxidase,catalase,and superoxide dismutase,while increasing the contents of malondialdehyde,hydrogen peroxide,and superoxide radical.Our results indicated a more significant yield loss in rice when subjected to combined salinity-drought stress.The individual and combined stresses of salinity and drought diminished antioxidant enzyme activities,inhibited leaf photosynthetic functions,accelerated leaf senescence,and subsequently lowered assimilate accumulation and grain yield. 展开更多
关键词 antioxidant defense system combined salinity-drought stress drought stress photosynthetic characteristics RICE salinity stress
下载PDF
A novel binary effective medium model to describe the prepeak stressstrain relationship of combined bodies of rock-like material and rock 被引量:1
2
作者 Tienan Wang Yue Zhai +2 位作者 Huan Gao Yubai Li Ruifeng Zhao 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2023年第5期601-616,共16页
Combined bodies of rock-like material and rock are widely encountered in geotechnical engineering,such as tunnels and mines.The existing theoretical models describing the stress-strain relationship of a combined body ... Combined bodies of rock-like material and rock are widely encountered in geotechnical engineering,such as tunnels and mines.The existing theoretical models describing the stress-strain relationship of a combined body lack a binary feature.Based on effective medium theory,this paper presents the governing equation of the“elastic modulus”for combined and single bodies under triaxial compressive tests.A binary effective medium model is then established.Based on the compressive experiment of concretegranite combined bodies,the feasibility of determining the stress threshold based on crack axial strain is discussed,and the model is verified.The model is further extended to coal-rock combined bodies of more diverse types,and the variation laws of the compressive mechanical parameters are then discussed.The results show that the fitting accuracy of the model with the experimental curves of the concretegranite combined bodies and various types of coal-rock combined bodies are over 95%.The crack axial strain method can replace the crack volumetric strain method,which clarifies the physical meanings of the model parameters.The variation laws of matrix parameters and crack parameters are discussed in depth and are expected to be more widely used in geotechnical engineering. 展开更多
关键词 combined body stress-strain relationship Hooke’s law Effective medium theory stress threshold determination
下载PDF
Polyaspartic acid mediates the absorption and translocation of mineral elements in tomato seedlings under combined copper and cadmium stress 被引量:8
3
作者 HU Mei-mei DOU Qiao-hui +2 位作者 CUI Xiu-min LOU Yan-hong ZHUGE Yu-ping 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2019年第5期1130-1137,共8页
Polyaspartic acid(PASP)is a nontoxic,biodegradable,environmentally friendly polymer and is widely used as a fertilizer synergist in agricultural production.In many old orchards and vegetable gardens,highly fertile soi... Polyaspartic acid(PASP)is a nontoxic,biodegradable,environmentally friendly polymer and is widely used as a fertilizer synergist in agricultural production.In many old orchards and vegetable gardens,highly fertile soil is often accompanied by severe heavy metal contamination.The present study was designed to investigate mineral element interactions mediated by PASP under copper(Cu)+cadmium(Cd)combined stress to provide reasonable suggestions for scientific fertilization.A pot experiment was conducted in which tomato seedlings served as plant materials.A concentration of 700 mgPASP and foliar spraying application methods were selected based on previous experiments.Four treatments were applied:normal soil(control(CK)),Cu+Cd(combined stress),Cu+Cd+PASP,and normal soil+PASP.The plant biomass,root activity,and mineral elements were measured,and these data were analyzed by Data Processing System(DPS)statistical software.The results showed that,under Cu+Cd combined stress,PASP promoted stem diameter growth,root activity and chlorophyll content and ultimately increased the biomass of tomato seedlings to different degrees.Moreover,the content of both Cu and Cd and their individual accumulation in plants decreased.PASP increased the distribution of Cu and Cd in the roots under Cu+Cd combined stress,and the translocation ability from the roots to shoots was significantly restricted.With respect to essential elements,PASP promoted mainly the absorption and translocation of potassium(K),calcium(Ca),and magnesium(Mg),which greatly exerted physiological roles.However,the variation trends of Cu and Cd under normal soil conditions contrasted with those under stress conditions.With respect to essential elements other than K,Ca,and Mg,PASP mostly restrained their absorption but promoted their translocation.The regulatory mechanism of PASP differed between the combined stress conditions and normal soil conditions.Under the combined stress conditions,PASP seemed to mainly promote these advantageous factors that exert physiological regulatory functions.Under normal soil conditions,PASP mainly acted as a biological stimulant or signaling molecule for increased nutrient efficiency,which caused greater biomass productivity. 展开更多
关键词 TOMATO SEEDLINGS polyaspartic acid Cu+Cd combined stress
下载PDF
Responses of antioxidant enzyme and photosynthesis in rape seedling to the combined stresses of acid rain and ultraviolet-B radiation 被引量:3
4
作者 LIANG Chan-juan HUANG Xiao-hua +1 位作者 TAO Wen-yi ZHOU Qing 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2005年第6期1038-1041,共4页
Effects of the simulated acid rain(AR) and ultraviolet-B(UV-B, 280-320 nm) radiation with a single or two ways simultaneously (AR + UV-B) on the antioxidant enzyme and photosynthesis of the rape seedlings were ... Effects of the simulated acid rain(AR) and ultraviolet-B(UV-B, 280-320 nm) radiation with a single or two ways simultaneously (AR + UV-B) on the antioxidant enzyme and photosynthesis of the rape seedlings were investigated by the hydroponic culture. The results of static experiment indicated that the tolerance of rape seedling to single stress(AR or UV-B) is stronger than that to dual stresses(AR + UV-B). Furthermore, the dual stresses had additive effect on catalase activity, and a synergistic effect on MDA content, net photosynthesis rate, water use efficiency as well as intercellular CO2 concentration. Meanwhile, it has an independent effect on chlorophyll content, stomatal conductance, and transpiration rate as well as membrane permeability. During 64 h restoration course, the dynamic change in the curves of physiological and biochemical indices were not identical, and none of them show a simple linear variation. According to the static and dynamic experiments, it was found that a responsive sequence of catalase activity, membrane permeability, MDA content and photosynthetic characteristics to the above-mentioned stresses was as follows: AR + UV-B 〉 UV-B 〉 AR. 展开更多
关键词 combined stresses elevated UV-B radiation simulated acid rain rape seedling CAT activity PHOTOSYNTHESIS
下载PDF
Combined stress waves with phase transition in thin-walled tubes 被引量:3
5
作者 宋卿争 唐志平 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2014年第3期285-296,共12页
The incremental constitutive relation and governing equations with combined stresses for phase transition wave propagation in a thin-walled tube are established based on the phase transition criterion considering both... The incremental constitutive relation and governing equations with combined stresses for phase transition wave propagation in a thin-walled tube are established based on the phase transition criterion considering both the hydrostatic pressure and the deviatoric stress. It is found that the centers of the initial and subsequent phase transition ellipses are shifted along the sigma-axis in the sigma tau-plane due to the tension-compression asymmetry induced by the hydrostatic pressure. The wave solution offers the 'fast' and 'slow' phase transition waves under combined longitudinal and torsional stresses in the phase transition region. The results show some new stress paths and wave structures in a thin-walled tube with phase transition, differing from those of conventional elastic-plastic materials. 展开更多
关键词 combined stress phase transition wave thin-walled tube shape memory alloy(SMA)
下载PDF
A STUDY ON THE EFFECT OF RADIAL INERTIA ON THE ELASTO-PLASTIC COMBINED STRESS WAVE PROPAGATION IN THIN-WALLED TUBES 被引量:2
6
作者 Li Yongchi Huang Chengyi Yuan Fuping Jin Yongmei 《Acta Mechanica Solida Sinica》 SCIE EI 2001年第1期58-66,共9页
An in-depth analysis of propagation characteristics ofelasto-plastic combined stress waves in circular thin-walled tubeshas been made. In obtaining the simple-wave solution, however, mostresearches have ignored the in... An in-depth analysis of propagation characteristics ofelasto-plastic combined stress waves in circular thin-walled tubeshas been made. In obtaining the simple-wave solution, however, mostresearches have ignored the influence of the circumferential stressrelated to the radial inertial ef- fect in the tubes. In this paperthe incremental elasto-plastic constitutive relations which areconve- nient for dynamic numerical analysis are adopted, and thefinite-difference method is used to study the evolution adpropagation of elasto-plastic combined stress waves in a thin-walledtube with the radial inertial effect of the tube considered. Thecalculation results are compared with those obtained when the radialinertial effect is not considered. The calculation results show thatthe radial inertial effect of a tube has a fairly great influence onthe propagation of elasto-plastic combined stress waves. 展开更多
关键词 circular thin-walled tube elasto-plastic combined stress waves radialinertial effect
下载PDF
The Combined Effects of High Temperature and Carbon Monoxide on Heat Stress Response 被引量:2
7
作者 邬堂春 贺涵贞 +4 位作者 吴扬 徐代根 屈伸 冯家德 张国高 《Journal of Huazhong University of Science and Technology(Medical Sciences)》 SCIE CAS 1995年第3期178-183,共6页
In this study,we have examined the effects of exposure to high temperature, carbon inonoxideor a combination of both conditions in a model system,the rat and in industrial workers.In the rat liver, HSP70 mRNA and HSP7... In this study,we have examined the effects of exposure to high temperature, carbon inonoxideor a combination of both conditions in a model system,the rat and in industrial workers.In the rat liver, HSP70 mRNA and HSP70 synthesis were measured by dot hybridization and western blot. The results showed that after a heat stress HSP70 mRNA and its product, HSP70 increased significantly and there was a synergism in the combined effects of high temperature and carbon monoxide exposure on the induction of HSP70 mRNA and HSP70 synthesis. Heat played a major role in this induction. The presence of antibodies to human HSP27, HSP60, HSP70,HSC73, HSP89 αand β in workers exposed to heat, carbon monoxide was also measured by western blot using purified HSPs as antigens. Plasma free amino acids were measured in the saine group of workers. The incidence of antibodies to HSP27 and HSP70 Was significantly higher in the workers working in an environment with extreme heat, and high carbon monoxide ernission than in a control group. The carbon monoxide exposed group showed the highest incidence of antibodies to HSPs. Although our previous results indicated that workers had an insufficient protein intake,plasma free amino acids tended to increase, especially in methionine and tryptophan two kinds of amino acids which are absent from the main stress protein, HSP70.These results suggest that the major problems that these workers may face are how to facilitate the use of plasma free amino acids and reduce the inhibition of synthesis of normal proteins when they are exposed to occupational harmful factors.These resultsalso add new information on the measurement of HSPs as a potential biomonitor to assess whether organisms are experiencing metabolic stress within their environment. 展开更多
关键词 high temperature4 carbon monoxide the combined effects HSP70 HSP70 mRNA antibodies to heat stress proteins plasma free amino acids
下载PDF
Combined Drought and Heat Stress in Rice: Responses, Phenotyping and Strategies to Improve Tolerance 被引量:1
8
作者 Maria Vera Jesus DA COSTA Yamunarani RAMEGOWDA +3 位作者 Venkategowda RAMEGOWDA Nataraja N.KARABA Sheshshayee M.SREEMAN Makarla UDAYAKUMAR 《Rice science》 SCIE CSCD 2021年第3期233-242,共10页
Simultaneous occurrence of drought and heat stress will have significant negative impact on rice yield,especially under upland conditions.The projected increase in global temperatures and reduced precipitation will in... Simultaneous occurrence of drought and heat stress will have significant negative impact on rice yield,especially under upland conditions.The projected increase in global temperatures and reduced precipitation will increase the frequency of occurrence and intensity of these stresses,threatening rice production.Despite recognizing the importance of combined stress in rice,the knowledge generated in this area is very limited.Though complex,understanding combined stress tolerance of rice under water saving cultivation is more critical towards development of climate resilient rice cultivars.Here,we summarized the effects of combined stress on rice physiology with more emphasis on reproductive stage.Omics responses,phenotyping and physiology challenges and potential strategies for improving combined stress tolerance in rice are also discussed. 展开更多
关键词 RICE drought stress heat stress combined stress FLOWERING grain filling omics response PHENOTYPING genetic enhancement
下载PDF
Photosynthetic Behaviour and Mineral Nutrition of Tamarix gallica Cultivated Under Aluminum and NaCl Combined Stress 被引量:2
9
作者 Dhouha Belhaj Sghaier Insaf Bankaji +2 位作者 Sylvia Pedro Isabel Caçador Noomene Sleimi 《Phyton-International Journal of Experimental Botany》 SCIE 2019年第3期239-252,共14页
The lack of knowledge of plant tolerance and differential response to aluminum(Al)encouraged many researchers,in the last decade,to elucidate Al toxicity and tolerance mechanisms.The current study reported the impact ... The lack of knowledge of plant tolerance and differential response to aluminum(Al)encouraged many researchers,in the last decade,to elucidate Al toxicity and tolerance mechanisms.The current study reported the impact of Al,a toxic element with negative effects on plant growth and development,in halophytic plant Tamarix gallica.Plants were subjected to different Al concentrations(0,200,500 and 800μM)with or without NaCl(200 mM)supplementation.Growth,photosynthesis and mineral content were assessed.Al stress had a significant decrease on shoots’biomass production between 19 to 41%,and a little variation on chlorophyll content and photosynthetic efficiency(Fo,Fm,Fv fluorescence’s and Fv/Fm).Furthermore,the Al-treatments did not affect significantly the content of potassium,calcium,and magnesium in different plant parts,whereas NaCl addition to the medium induced a decrease in these elements’concentrations.Our results have shown that T.gallica is able to accumulate the high levels of Al in shoots and roots,6288μg.g^(-1) DW and 7834μg.g^(-1) DW respectively.It is considered as a hyperaccumulator plant of Al.In addition,Na+contents in shoots and roots exceed 23000μg.g^(-1) DW.Therefore,T.gallica presents a high tolerance at the same time to Al and NaCl phytotoxicity,so it is interesting to use in phytoremediation programs. 展开更多
关键词 Halophyte tolerance combined stress photosynthetic pigments chlorophyll fluorescence Al-accumulation nutrients uptake
下载PDF
Propagation of combined longitudinal and torsional stress waves in a functionally graded thin-walled tube 被引量:1
10
作者 Shitang CUI Xiaojun NI 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2021年第12期1717-1732,共16页
An analytical model for the propagation of combined stress waves in a functionally graded thin-walled tube subjected to combined longitudinal and torsional impact loading is established.The material properties of the ... An analytical model for the propagation of combined stress waves in a functionally graded thin-walled tube subjected to combined longitudinal and torsional impact loading is established.The material properties of the tube are assumed to be continuously graded along the length according to a power law function with respect to the volume fractions of the constituents.The generalized characteristic theory is used to analyze the main features of the characteristic wave speeds and simple wave solutions in the functionally graded thin-walled tube.The finite difference method is used to discretize the governing equations.Two types of typical solutions are obtained for the functionally graded tube and the homogeneous tube subjected to combined longitudinal and torsional step loading.The numerical results reveal some abnormal phenomena in the stress path and wave process of the functionally graded thin-walled tube. 展开更多
关键词 elastoplastic behavior combined stress wave finite difference scheme thinwalled tube
下载PDF
Effect of epidural block combined intravenous general anesthesia stress on the stress response and T lymphocyte subsets in patients with breast cancer undergoing radical mastectomy 被引量:2
11
作者 Yuan Yao Yong-Sheng Wu +1 位作者 Hong-Xia Zhu Xin-Jing Su 《Journal of Hainan Medical University》 2017年第18期120-123,共4页
Objective: To investigate the effect of epidural block combined with intravenous anesthesia on stress response and T lymphocyte subsets in patients with breast cancer undergoing radical mastectomy. Methods: In our hos... Objective: To investigate the effect of epidural block combined with intravenous anesthesia on stress response and T lymphocyte subsets in patients with breast cancer undergoing radical mastectomy. Methods: In our hospital from July 2016 to June 2017 undergoing radical mastectomy for breast cancer of 88 patients were randomly divided into observation group and control group of 44 cases, 2 patients underwent routine preoperative preparation, and routine blood pressure, heart rate, pulse, oxygen saturation, ECG monitoring, control group with intravenous anesthesia. The observation group was treated with epidural block combined with intravenous anesthesia. 2 groups of patients before anesthesia, 30 MIM (T0), 1 h after skin incision (T1), 4 h after operation (T2), 24 h after operation (T3), 48 h after operation (T4) from peripheral venous blood were measured by interleukin-8 (IL-8) and interferon gamma (IFN-γ), cortisol (Cor), prolactin (PRL), growth hormone (GH) and T lymphocyte subsets (CD3+, CD4+, CD8+), the calculation of CD4+/CD8+ value. Results: the serum IL-8 level of T1, T2, T3and T4 decreased gradually, were lower than at T0, and the control group at each time point had no significant difference, T1, T2, T3group, T4IL-8 levels lower than the control group;the 2 groups of serum IFN-γ levels T1 and T2had no significant change, T3and T4increased gradually, was higher than that of T0, but no significant difference between the 2 groups of IFN-γ levels. 2 serum Cor levels peaked at T1, decreased at T2, was higher than that of T0, T3, T4returned to T0, the observation group T1, T2Cor level lower than the control group;the serum PRL levels of 2 groups reached a peak at T1, T2, T3at the time of T4decreased gradually, was higher than that of T0, T1, T2, T3of the observation group at the PRL level is lower than the control group;the serum level of GH 2 in group T1increased gradually, reached a peak at T2, T3and T4 decreased gradually, was higher than that of T0, the observation group T1, T2, T3, T4, GH levels lower than the control group. 2 groups of CD3+ decreased gradually in T1, T2, were lower than T0, T3, T4returned to T0, the observation group T1, T2CD3+ was higher than the control group;group CD4+ decreased gradually in T1, T2, T3and T4were lower than control, T0when, and the observation group CD4+ in T1, T2, T3, T4, no significant changes were observed in group T1, T2, T3, T4and CD4+ higher than that of the control group;the 2 group CD8+ had no obvious changes in T1, T2, T3, T4;observation group CD4+/CD8+ decreased gradually in T1, T2, were lower than T0, T3, T4returned to T0, the observation group T1, T2CD4+/CD8+ was higher than the control group. Conclusion: epidural block combined with intravenous anesthesia for breast cancer radical mastectomy can effectively relieve the stress and inflammatory reaction, alleviate the immunosuppression, and help to restore the postoperative immune function. 展开更多
关键词 Total INTRAVENOUS ANESTHESIA EPIDURAL block combined INTRAVENOUS general ANESTHESIA Radical MASTECTOMY stress response T lymphocyte subsets
下载PDF
Natural product-induced oxidative stress-synergistic anti-tumor effects of chemotherapeutic agents
12
作者 Shu-Fan Wang Shi-Qi Dong +3 位作者 Quan Dong Wen-Xin Lin Mei Dong Duo Liu 《Traditional Medicine Research》 2024年第3期10-23,共14页
Reactive oxygen species are closely related to tumor development.In recent years,reactive oxygen species has become a hot spot in tumor therapy,and many natural substances in nature contain compound components with an... Reactive oxygen species are closely related to tumor development.In recent years,reactive oxygen species has become a hot spot in tumor therapy,and many natural substances in nature contain compound components with anti-tumor effects.However,there is a lack of discussion on the synergistic anti-tumor effects of natural products in combination with chemotherapeutic drugs through reactive oxygen species.The terms“natural products”,“reactive oxygen species”,“anti-tumor”,and“chemotherapy”were used to identify the synergistic effects of natural products.We conducted a systematic literature search in PubMed and Web of Science databases for relevant research articles and reviews published in recent years.We systematically summarized the studies related to anti-tumor active ingredients in natural compounds in the field of reactive oxygen species in recent years.A total of 77 relevant literatures were included.Among them,45 literatures containing various natural products such as terpenoids,flavonoids,alkaloids,etc.exert anti-tumor effects by regulating reactive oxygen species levels,and 32 literatures regarding adjunctive role of natural products in anti-tumor therapy.In this study,we found that natural products exert anti-tumor effects by elevating reactive oxygen species levels.It provides strong theoretical support for future clinical studies. 展开更多
关键词 nature products TUMOR reactive oxygen species combination chemotherapy oxidative stress
下载PDF
THE INVESTIGATION ON DYNAMIC FRACTURE BEHAVOUR OF MATERIALS UNDER COMPRESSIVE-SHEAR COMBINED STRESS WAVES
13
作者 马维 段祝平 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2000年第4期335-346,共12页
In this paper,an improved plate impact experimental technique is presented for studying dynamic fracture mechanism of materials,under the conditions that the impacting loading is provided by a single pulse and the loa... In this paper,an improved plate impact experimental technique is presented for studying dynamic fracture mechanism of materials,under the conditions that the impacting loading is provided by a single pulse and the loading time is in the sub-microsecond range.The impacting tests are carried out on the pressure-shear gas gun.The loading rate achieved is dK/dt~10~8 MPam^(1/2)s^(-1).With the elimination of influence of the specimen boundary,the plane strain state of a semi-infinite crack in an infinite elastic plate is used to simulate the deformation fields of crack tip. The single pulses are obtained by using the 'momentum trap'technique.Therefore, the one-time actions of the single pulse are achieved by eradicating the stress waves reflected from the specimen boundary or diffracted from the crack surfaces.In the current study,some important phenomena have been observed.The special loading of the single pulse can bring about material damage around crack tip,and affect the material behavior,such as kinking and branching of the crack propagation.Failure mode transitions from mode Ⅰ to mode Ⅱ crack are observed under asymmetrical impact conditions.The mechanisms of the dynamic crack propagation are consistent with the damage failure model. 展开更多
关键词 single pulse compressive-shear combined stress wave pressureshear gas gun
下载PDF
Metabolic responses to combined water deficit and salt stress in maize primary roots
14
作者 LI Peng-cheng YANG Xiao-yi +6 位作者 WANG Hou-miao PAN Ting YANG Ji-yuan WANG Yun-yun XU Yang YANG Ze-feng XU Chen-wu 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2021年第1期109-119,共11页
Soil water deficit and salt stress are major limiting factors of plant growth and agricultural productivity. The primary root is the first organ to perceive the stress signals for drought and salt stress. In this stud... Soil water deficit and salt stress are major limiting factors of plant growth and agricultural productivity. The primary root is the first organ to perceive the stress signals for drought and salt stress. In this study, maize plant subjected to drought, salt and combined stresses displayed a significantly reduced primary root length relative to the control plants. GC-MS was used to determine changes in the metabolites of the primary root of maize in response to salt, drought and combined stresses. A total of 86 metabolites were measured, including 29 amino acids and amines, 21 organic acids, four fatty acids, six phosphoric acids, 10 sugars, 10 polyols, and six others. Among these, 53 metabolites with a significant change under different stresses were identified in the primary root, and the content of most metabolites showed down-accumulation. A total of four and 18 metabolites showed significant up-and down-accumulation to all three treatments, respectively. The levels of several compatible solutes, including sugars and polyols, were increased to help maintain the osmotic balance. The levels of metabolites involved in the TCA cycle, including citric acid, ketoglutaric acid, fumaric acid, and malic acid, were reduced in the primary root. The contents of metabolites in the shikimate pathway, such as quinic acid and shikimic acid, were significantly decreased. This study reveals the complex metabolic responses of the primary root to combined drought and salt stresses and extends our understanding of the mechanisms involved in root responses to abiotic tolerance in maize. 展开更多
关键词 MAIZE primary root combination stress DROUGHT high salt stress metabolomics
下载PDF
THE TOPOLOGICAL OPTIMIZATION FOR TRUSS STRUCTURES WITH STRESS CONSTRAINTS BASED ON THE EXIST-NULL COMBINED MODEL 被引量:9
15
作者 隋允康 于新 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 1998年第4期363-370,共8页
A new exist-null combined model is proposed for the structural topology optimization. The model is applied to the topology optimization of the truss with stress constraints. Satisfactory computational result can be ob... A new exist-null combined model is proposed for the structural topology optimization. The model is applied to the topology optimization of the truss with stress constraints. Satisfactory computational result can be obtained with more rapid and more stable convergence as compared with the cross-sectional optimization. This work also shows that the presence of independent and continuous topological variable motivates the research of structural topology optimization. 展开更多
关键词 structural topology optimization independent and continuous topological variable smooth model exist-null combination TRUSS stress constraint
全文增补中
Effects of acupuncture combined with drug anesthesia on stress reaction and cognitive function in senior patients with total hip arthroplasty
16
作者 Lin-zhi Wei Ning Qu 《Journal of Hainan Medical University》 2019年第17期66-70,共5页
Objective: To investigate the effects of acupuncture combined with anesthesia on stress and cognitive function in senior patients with total hip arthroplasty. Methods: A total of 89 patients who underwent total hip re... Objective: To investigate the effects of acupuncture combined with anesthesia on stress and cognitive function in senior patients with total hip arthroplasty. Methods: A total of 89 patients who underwent total hip replacement between January 2016 and May 2018 were collected. According to whether acupuncture anesthesia was applied during total hip replacement, the patients were divided into acupuncture combined anesthesia group and drug anesthesia group. Fasting venous blood (3mL) was collected before the operation without electrical stimulation and after the operation. Cortisol (Cor) and β-endorphin (β-EP) were detected by radioimmunoassay, and neuron-specific enolase (NSE) was detected by electrochemical luminescence immunoassay. The levels of s-100β protein (s-100β), c-reactive protein (CRP) and tumor necrosis factor-α (TNF-α) were determined by ELISA. Flow cytometry was used to determine the ratio of T cell subsets (CD3+) and natural killer cells (NK cells) in the blood. Results: The levels of Cor, β-EP, NSE, S-100β, CRP, TNF-α and the ratio of NK cell, CD3+ between the two groups have no significant differences before operation (P>0.05). Serum levels of Cor, β-EP, NSE, S-100β, CRP and TNF-α in patients in the acupuncture combined with drug anesthesia group and the single drug anesthesia group were significantly higher than those before surgery (P<0.05). In addition, serum levels of Cor, β-EP, NSE, S-100β, CRP, TNF-α in the acupuncture combined with anesthesia group were significantly lower than those in the drug group alone (P<0.05). There was no significant difference in NK cell and CD3+ ratio between postoperative and preoperative in the acupuncture combined with drug anesthesia group (P>0.05). The ratio of NK cells and CD3+ in the pure drug anesthesia group was significantly lower than that before surgery (P<0.05). Conclusion: Acupuncture combined with drug anesthesia can effectively reduce the inflammatory stress response of patients undergoing total hip arthroplasty, relieve the immune suppression caused by surgery and anesthesia, reduce the damage to the nervous system, and have a good influence in the cognitive function of the senior patients. 展开更多
关键词 ACUPUNCTURE combined ANESTHESIA Total hip ARTHROPLASTY stress response Cognitive function
下载PDF
Effect of combined spinal and epidural anesthesia on the level of pain media, stress indicators and inflammatory factors in patients undergoing high altitude cesarean section
17
作者 Tian Shun Huang Cui-yuan +1 位作者 Pu Le-hua Tian Yu 《Journal of Hainan Medical University》 2019年第17期71-75,共5页
Objective: To discuss the effect of combined spinal and epidural anesthesia on the levels of pain media, stress indicators and inflammatory factors in patients undergoing high altitude cesarean section. Methods: Eight... Objective: To discuss the effect of combined spinal and epidural anesthesia on the levels of pain media, stress indicators and inflammatory factors in patients undergoing high altitude cesarean section. Methods: Eighty patients who underwent cesarean section in our hospital from January 2017 to April 2019 were enrolled in the hospital. They were divided into two groups according to the patient's anesthesia. Fourty patients receiving epidural anesthesia were included in the control group, and another 40 patients received lumbar stiffness. The combined anesthesia patient was included in the observation group. Changes in pain mediators [Serum neuropeptide Y (NPY), endorphin (β-EP), substance P (SP)], stress indicators [Serum cortisol (Cor), C-peptide (C-P), advanced oxidative protein product (AOPP)], inflammatory factor levels [Hypersensitive C-reactive protein (hs-CRP), tumor necrosis factor-alpha (TNF-α)], and immunoglobulin levels [Serum IgA, IgG, IgM] were compared between the two groups. Results: Before anesthesia, there were no significant difference in pain media, stress index, inflammatory factor level and immunoglobulin level between the two groups (P>0.05). At 12 h after operation, the two groups of patients were NPY, β-EP, SP, Cor. The levels of C-P, AOPP, hs-CRP and TNF-α were higher than those before operation (P<0.05). The levels of IgA, IgG and IgM were lower than those before operation (P<0.05). Among them, observation group NPY, β-EP, SP, Cor, C-P, AOPP, hs-CRP and TNF-α were significantly lower than those of the control group (P<0.05). The serum levels of IgA, IgG and IgM were significantly higher than those of the control group (P<0.05). Conclusion: Combined spinal and epidural anesthesia can more effectively alleviate maternal pain in high altitude cesarean section, more effectively reduce the inflammatory stress response of patients, promote the humoral immune function of patients, and is beneficial to the early recovery of maternal postoperative, and has high clinical value. 展开更多
关键词 combined SPINAL and EPIDURAL anesthesia High ALTITUDE area CESAREAN section surgery PAIN stress Inflammation
下载PDF
Combined back-analysis method of ground stress based on refined geological modeling
18
作者 Liu Donghai Zheng Jiang Wang Qian 《Engineering Sciences》 EI 2012年第4期43-50,共8页
A new back-analysis method of ground stress is proposed with comprehensive consideration of influence of topography, geology and nonlinear physical mechanical properties of rock on ground stress. This method based on ... A new back-analysis method of ground stress is proposed with comprehensive consideration of influence of topography, geology and nonlinear physical mechanical properties of rock on ground stress. This method based on non-uniform rational B-spline (NURBS) technology provides the means to build a refined three-dimensional finite element model with more accurate meshing under complex terrain and geological conditions. Meanwhile, this method is a back-analysis of ground stress with combination of multivariable linear regression model and neural network (ANN) model. Firstly, the regression model is used to fit approximately boundary loads. Regarding the regressed loads as mean value, some sets of boundary loads with the same interval are constructed according to the principle of orthogonal design, to calculate the corresponding ground stress at the observation positions using finite element method. The results (boundary loads and the corresponding ground stress) are added to the samples for ANN training. And on this basis, an ANN model is established to implement higher precise back-analysis of initial ground stress. A practical application case shows that the relative error between the inversed ground stress and observed value is mostly less than 10 %, which can meet the need of engineering design and construction requirements. 展开更多
关键词 初始地应力 反分析方法 地质建模 多元线性回归模型 基础 三维有限元模型 非均匀有理B样条 神经网络模型
下载PDF
A HALF PLANE CRACK UNDER THREE-DIMENSIONAL COMBINED MODE IMPACT LOADING 被引量:1
19
作者 柳春图 李湘平 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 1994年第1期40-48,共9页
The dynamic stress intensity factor history for a half plane crack in an otherwise unbounded elastic body, with the crack faces subjected to a traction distribution consisting of two pairs of suddenly-applied shear li... The dynamic stress intensity factor history for a half plane crack in an otherwise unbounded elastic body, with the crack faces subjected to a traction distribution consisting of two pairs of suddenly-applied shear line loads is consid- ered. The analytic expression for the combined mode stress intensity factors as a function of time is obtained. The method of solution is based on the application of integral transforms and the Wiener-Hopf technique. Some features of the solutions are discussed and graphical numerical results are presented. 展开更多
关键词 impact line loads a half plane crack combined mode dynamic stress intensity factor
下载PDF
Molecular Targets of Combined Natural Antioxidants Against Diabetes in Streptozotocin-induced Diabetic Mice
20
作者 SONG Yang1,2, GAO Zhong-li2, DU Zhen-wu1, PIAO Song-lan1, WANG Ling-ling1, WANG Qing3 and ZHANG Gui-zhen1 1. Central Research Department, 2. Department of Orthopaedics, 3. Department of Endocrinology, China-Japan Union Hospital of Jilin University, Changchun 130033, P. R. China 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2012年第1期96-102,共7页
Natural antioxidants, due to the different chemical structures and their unique biological protection effects on islet cell, have been received much attention in applied chemistry field for developing a new diabetic d... Natural antioxidants, due to the different chemical structures and their unique biological protection effects on islet cell, have been received much attention in applied chemistry field for developing a new diabetic drug. However, the molecular targets of the islet cell protection have been remained obscure. For investigating molecular targets of combined natural antioxidant’s(CNA) roles in against diabetes, type 1 diabetic mouse model was made by multiple injection of low doses of streptozotocin into C57BL mice. Two combinations of natural antioxidants were orally supplemented to the mice. Blood glucose level, glutathione peroxidase(GSH-Px) and superoxide dismutase (SOD) activities, and malondialdehyde(MDA) contents were measured via biochemical assays. Tumor necrosis factor α(TNF-α), interferon γ(IFN-γ) and Interleukin-12(IL-12) in CD4+ Peripheral blood mononuclear cells(PBMC) were evaluated with flow cytometry(FCM). In situ hybridization(ISH) and immunohistochemistry(IHC) were used to detect insulin gene expression. The results demonstrate both the combinations significantly: increased GSH-px and SOD, but decreased MDA levels in pancreas(p〈0.05―0.01); up-regulated insulin expression at both mRNA and protein levels in islet cells(p〈0.05―0.01); down-regulated TNF-α and IL-12 expression in PBMC(p〈0.05―0.01). Our data suggest that the CAN may regulate multiple key molecular targets related to β cell function, including reduction of oxidative stress and pre-inflammatory cytokines, and upregulate insulin gene expression to reduce the development of diabetes. 展开更多
关键词 combined natural antioxidant DIABETES Insulin gene expression Oxidative stress Pro-inflammatory cytokine
下载PDF
上一页 1 2 69 下一页 到第
使用帮助 返回顶部