期刊文献+
共找到998篇文章
< 1 2 50 >
每页显示 20 50 100
Supplementation of vitamin E or a botanical extract as antioxidants to improve growth performance and health of growing pigs housed under thermoneutral or heat-stressed conditions
1
作者 Ysenia V.Silva‑Guillen Consuelo Arellano +3 位作者 Jeffrey Wiegert R.Dean Boyd Gabriela E.Martinez Eric van Heugten 《Journal of Animal Science and Biotechnology》 SCIE CAS CSCD 2024年第3期1101-1118,共18页
Background Heat stress has severe negative consequences on performance and health of pigs,leading to significant economic losses.The objective of this study was to investigate the effects of supplemental vitamin E and... Background Heat stress has severe negative consequences on performance and health of pigs,leading to significant economic losses.The objective of this study was to investigate the effects of supplemental vitamin E and a botanical extract in feed or drinking water on growth performance,intestinal health,and oxidative and immune status in grow-ing pigs housed under heat stress conditions.Methods Duplicate experiments were conducted,each using 64 crossbred pigs with an initial body weight of 50.7±3.8 and 43.9±3.6 kg and age of 13-week and 12-week,respectively.Pigs(n=128)were housed individually and assigned within weight blocks and sex to a 2×4 factorial arrangement consisting of 2 environments(thermo-neutral(21.2℃)or heat-stressed(30.9℃))and 4 supplementation treatments(control diet;control+100 IU/L of D-α-tocopherol in water;control+200 IU/kg of DL-α-tocopheryl-acetate in feed;or control+400 mg/kg of a botanical extract in feed).Results Heat stress for 28 d reduced(P≤0.001)final body weight,average daily gain,and average daily feed intake(-7.4 kg,-26.7%,and-25.4%,respectively)but no effects of supplementation were detected(P>0.05).Serum vitamin E increased(P<0.001)with vitamin E supplementation in water and in feed(1.64 vs.3.59 and 1.64 vs.3.24),but not for the botanical extract(1.64 vs.1.67 mg/kg)and was greater when supplemented in water vs.feed(P=0.002).Liver vitamin E increased(P<0.001)with vitamin E supplementations in water(3.9 vs.31.8)and feed(3.9 vs.18.0),but not with the botanical extract(3.9 vs.4.9 mg/kg).Serum malondialdehyde was reduced with heat stress on d 2,but increased on d 28(interaction,P<0.001),and was greater(P<0.05)for antioxidant supplementation compared to control.Cellular proliferation was reduced(P=0.037)in the jejunum under heat stress,but increased in the ileum when vitamin E was supplemented in feed and water under heat stress(interaction,P=0.04).Tumor necrosis factor-αin jejunum and ileum mucosa decreased by heat stress(P<0.05)and was reduced by vitamin E sup-plementations under heat stress(interaction,P<0.001).Conclusions The addition of the antioxidants in feed or in drinking water did not alleviate the negative impact of heat stress on feed intake and growth rate of growing pigs. 展开更多
关键词 Botanical extract Growing pigs heat stress Immune status Oxidative status TOCOPHEROL Water
下载PDF
Rapid authentication of different herbal medicines by heating online extraction electrospray ionization mass spectrometry
2
作者 Zidong Qiu Chaofa Wei +9 位作者 Xiang Li Changjiangsheng Lai Zhilai Zhan Yan Jin Li Zhou Qingxiu Hao Jian Yang Shuanglong Wang Liping Kang Luqi Huang 《Journal of Pharmaceutical Analysis》 SCIE CAS CSCD 2023年第3期296-304,共9页
The rapid and accurate authentication of traditional Chinese medicines(TCMs)has always been a key scientific and technical problem in the field of pharmaceutical analysis.Herein,a novel heating online extraction elect... The rapid and accurate authentication of traditional Chinese medicines(TCMs)has always been a key scientific and technical problem in the field of pharmaceutical analysis.Herein,a novel heating online extraction electrospray ionization mass spectrometry(H-oEESI-MS)was developed for the rapid and direct analysis of extremely complex substances without the requirement for any sample pretreatment or pre-separation steps.The overall molecular profile and fragment structure features of various herbal medicines could be completely captured within 10–15 s,with minimal sample(<0.5 mg)and solvent consumption(<20μL for one sample).Furthermore,a rapid differentiation and authentication strategy for TCMs based on H-oEESI-MS was proposed,including metabolic profile characterization,characteristic marker screening and identification,and multivariate statistical analysis model validation.In an analysis of 52 batches of seven types of Aconitum medicinal materials,20 and 21 key compounds were screened out as the characteristic markers of raw and processed Aconitum herbal medicines,respectively,and the possible structures of all the characteristic markers were comprehensively identified based on Compound Discoverer databases.Finally,multivariate statistical analysis showed that all the different types of herbal medicines were well differentiated and identified(R^(2)X>0.87,R^(2)Y>0.91,and Q^(2)>0.72),which further verified the feasibility and reliability of this comprehensive strategy for the rapid authentication of different TCMs based on H-oEESI-MS.In summary,this rapid authentication strategy realized the ultra-high-throughput,low-cost,and standardized detection of various complex TCMs for the first time,thereby demonstrating wide applicability and value for the development of quality standards for TCMs. 展开更多
关键词 heating online extraction electrospray ionization mass spectrometry Rapid authentication Traditional Chinese medicine
下载PDF
Coupled heat-fluid-solid numerical study on heat extraction potential of hot dry rocks based on discrete fracture network model
3
作者 Daobing Wang Haiyan Zhu +6 位作者 Marembo Micheal Xuanhe Tang Qin Li Xiangyi Yi Dongliang Sun Bo Yu Qiang Liu 《Energy Geoscience》 2023年第4期81-94,共14页
Fracture networks within hot dry rock(HDR)geothermal reservoirs are complex,and heat extraction via water injection is thus a coupled process of heat-fluid-solid multifield.In this paper,utilizing the theory of normal... Fracture networks within hot dry rock(HDR)geothermal reservoirs are complex,and heat extraction via water injection is thus a coupled process of heat-fluid-solid multifield.In this paper,utilizing the theory of normally distributed random functions,we develop a corresponding pre-processing subprogram to establish a discrete network model of complex fracture distribution in HDR reservoirs;then construct a heat-fluid-solid finite element model for heat extraction via water injection and compare the numerical solution with the analytical solution of the one-dimensional non-isothermal consolidation problem for verification.The numerical simulation results show that the main factors affecting the heat extraction efficiency of HDR reservoirs include fracture width,fracture density,fracture permeability,and matrix permeability.When a HDR reservoir is injected with water for heat extraction,there is a certain threshold value of these influential parameters,beyond which the outlet temperature drops significantly,resulting in an obvious thermal breakthrough.When injecting water for heat extraction,the values of these parameters should be controlled and kept at a reasonable level,otherwise,the HDR reservoir may enter a thermal breakthrough stage in advance,which is not conducive for long-period heat extraction.Influenced by the random distribution of complex fractures,the leading edge of the cold front may present an irregular distribution.During the process of heat extraction,the stress gradually changes from a compressional state to a tensile state,which induces further damage to the HDR reservoir. 展开更多
关键词 Enhanced geothermal system Seepage and heat transfer Complex fractures heat extraction efficiency Multifield coupling
下载PDF
Convective heat transfer of water flow in intersected rock fractures for enhanced geothermal extraction 被引量:3
4
作者 Yuedu Chen Zhihong Zhao Huan Peng 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2022年第1期108-122,共15页
Numerous intersected rock fractures constitute the fracture network in enhanced geothermal systems.The complicated convective heat transfer behavior in intersected fractures is critical to the heat recovery in fractur... Numerous intersected rock fractures constitute the fracture network in enhanced geothermal systems.The complicated convective heat transfer behavior in intersected fractures is critical to the heat recovery in fractured geothermal reservoirs.A series of three-dimensional intersected fracture models is constructed to perform the flow-through heat transfer simulations.The geometry effects of dead-end fractures(DEFs)on the heat transfer are evaluated in terms of intersected angles,apertures,lengths,and the connectivity.The results indicate that annular streamlines appear in the rough DEF and cause an ellipse distribution of the cold front.Compared to plate DEFs,the fluid flow in the rough DEF enhances the heat transfer.Both the increment of outlet water temperatureΔToutand the ratio of heat production Qrpresent the largest at the intersected angle of 90°while decline with the decrease of the intersected angle between the main flow fracture(MFF)and the DEFs.The extension of the length of intersected DEFs is beneficial to heat production while enhancing its aperture is not needed.Solely increasing the number of intersected DEFs induces a little increase of heat extraction,and more significant heat production can be obtained through connecting these DEFs with the MFF forming the flow network. 展开更多
关键词 heat transfer Fracture intersection Fluid flow Rough fracture Geothermal extraction
下载PDF
Dynamic analysis of heat extraction rate by supercritical carbon dioxide in fractured rock mass based on a thermal-hydraulic-mechanics coupled model 被引量:3
5
作者 Chunguang Wang Xingkai Shi +7 位作者 Wei Zhang Derek Elsworth Guanglei Cui Shuqing Liu Hongxu Wang Weiqiang Song Songtao Hu Peng Zheng 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2022年第2期225-236,共12页
Heat production from geothermal reservoirs is a typical heat transfer process involving a cold working fluid contacting a hot rock formation.Compared to the thermal-physical characteristics of water,supercritical CO_(... Heat production from geothermal reservoirs is a typical heat transfer process involving a cold working fluid contacting a hot rock formation.Compared to the thermal-physical characteristics of water,supercritical CO_(2)(scCO_(2))has a higher heat storage capacity over a wide temperature-pressure range and may be favored as a heat transfer fluid.Singularly characteristic of scCO_(2)-based heat extraction is that the hydraulic-thermal properties of the scCO_(2) vary dramatically and dynamically with the spatial pressure gradient during unsteady-state flow along fracture.This highly nonlinear behavior presents a challenge in the accurate estimation of heat extraction efficiency in scCO_(2)-based EGS.In this paper,a thermal-h ydraulic-mechanical(THM)coupled model is developed by considering deformation of the fractured reservoir,non-Darcy flow and the varying thermal-physical properties of scCO_(2).The proposed model is validated by matching the modeling temperature distribution with published data.The results show that during continuous injection of scCO_(2),the fracture first widens and then narrows,ultimately reopening over the long term.The sequential fracture deformation behaviors are in response to the combined impacts of mechanical compression and thermally-induced deformation.By controlling the injection parameters of the scCO_(2),it is found that the heat extraction rate is positively correlated to its pore pressure or mass flow rate.The heat extraction rate can be significantly enhanced,when the inlet temperature of scCO_(2) is below its critical temperature.As a result,the heat increment recovered per unit mass of scCO_(2) decreases as the hot rock is gradually cooled.Meanwhile,the heat increment recovered per unit mass of scCO_(2) decreases by increasing the inlet temperature of scCO_(2) or its mass flow rate,but increases as the outlet pressure rises.Furthermore,multi-linear regression indicates that controlling the inlet temperature of the scCO_(2) can significantly improve the thermodynamic efficiency of heat extraction. 展开更多
关键词 Supercritical CO_(2) heat extraction Hot rock Geothermal energy Fracture-matrix interaction
下载PDF
A novel experimental setup with sand trunk for heat extraction of geothermal heat exchanger
6
作者 姜益强 姚杨 +1 位作者 陈益明 马最良 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2008年第6期809-813,共5页
A novel experimental setup was developed to study the heat extraction of geothermal heat exchanger(GHE)in different operational modes under adiabatic and isothermal boundaries.The experimental setup consists of a sand... A novel experimental setup was developed to study the heat extraction of geothermal heat exchanger(GHE)in different operational modes under adiabatic and isothermal boundaries.The experimental setup consists of a sand trunk,a tailored water chiller,a natural cold source unit,two water boxes containing hot water and cool water,and a data acquisition system.The experimental results indicate that the volume flow rate of the entering water is a main factor affecting the heat extraction;furthermore,the heat extraction value per meter pipe decreases gradually along the heat extraction pipe and increases with the increase of the incoming water volume flow rate.Therefore,this novel experimental setup may be helpful to further study the operation performance of GHE in different types of soil. 展开更多
关键词 heat extraction GHE experimental setup sand trunk
下载PDF
Effects of Bupleurum extract on blood metabolism, antioxidant status and immune function in heat-stressed dairy cows 被引量:3
7
作者 CHENG Jian-bo FAN Cai-yun +5 位作者 SUN Xian-zhi WANG Jia-qi ZHENG Nan ZHANG Xing-kai QIN Jun-jie WANG Xiu-min 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2018年第3期657-663,共7页
This experiment was conducted to evaluate the effects of Bupleurum extract (BE) on blood metabolites, antioxidant status, and immune function in dairy cows under heat stress. Forty lactating Holstein cows were rando... This experiment was conducted to evaluate the effects of Bupleurum extract (BE) on blood metabolites, antioxidant status, and immune function in dairy cows under heat stress. Forty lactating Holstein cows were randomly assigned to 1 of 4 treatments. The treatments consisted of 0, 0.25, 0.5, and 1.0 g of BE kg-1 dry matter. Supplementation with BE decreased (P〈0.05) blood urea nitrogen (BUN) contents and increased blood total protein (TP) and albumin (ALB) levels compared with control cows, but it had no effects (P〉0.05) on blood glucose (GLU), nonesterified fatty acid (NEFA), total triglycedde (TG), low-density lipoprotein cholesterol (LDL-C), and high density lipoprotein cholesterol (HDL-C). Compared with control cows, cows fed BE had higher (P〈0.05) superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity. However, supplementation with BE had no effect (P〉0.05) on total antioxidant capacity (T-AOC) or malondialdehyde (MDA) levels. The immunoglobulin (Ig) A and G contents increased (P〈0.05) in cows fed 0.25 or 0.5 g of BE kg-1. Interleukin (IL)-2 and IL-4 levels were higher (P〈0.05) in cows fed 0.5 and 1.0 g of BE kg-1, and IL-6 was significantly elevated (P〈0.05) in cows fed 0.5 g of BE kg-1. There were no treatment effects (P〉0.05) on the CD4+ and CD8+ T lymphocyte ratios, CD4+/CD8+ratio, or tumor necrosis factor-α (TNF-α) level among the groups. These findings suggest that BE supplementation may improve protein metabolism, in addition to enhancing antioxidant activity and immune function in heat-stressed dairy cows. 展开更多
关键词 Bupleurum extract blood metabolites heat stress dairy cows
下载PDF
Efficient Extraction of Agarose from Red Algae Using Ionic Liquids 被引量:3
8
作者 Tushar J. Trivedi Arvind Kumar 《Green and Sustainable Chemistry》 2014年第4期190-201,共12页
We explored the possibility of using ionic liquids (ILs) as medium for efficient extraction of agarose via dissolution of red algae under varying conditions of heating or microwave irradiation. As compared to conventi... We explored the possibility of using ionic liquids (ILs) as medium for efficient extraction of agarose via dissolution of red algae under varying conditions of heating or microwave irradiation. As compared to conventional methods, a very high extraction yield of good quality agarose (as high as 39 wt%) could be achieved depending upon the nature of used IL and applied experimental conditions. Purity of extracted agarose was confirmed from various spectral and analytical techniques, such as 1H and 13C NMR, FTIR, circular dichroism (CD), gel permeation chromatography (GPC) and thermogravimetric analysis (TGA). The physicochemical properties, such as gelling or melting temperature, viscosity and gel strength of extracted agarose hydrogels have been measured and compared with the agarose obtained from similar source reported in the literature. ILs were recovered after the extraction of agarose and were reused for further extraction experiments. % Recycling and extraction ability of recycled ILs in different cycles have been measured. The developed extraction process of utilizing ILs as medium is easy, simple and highly efficient as compared to the conventional methods of agarose extraction from algae. 展开更多
关键词 Red ALGAE IONIC Liquids AGAROSE Thermal or Microwave heating RECYCLING extraction Ability
下载PDF
Regeneration of waste activated carbon after extracting gold with steam under microwave heating:Optimization using response surface methodology 被引量:2
9
作者 左勇刚 张利波 +3 位作者 彭金辉 C.SRINIVASAKANNAN 刘秉国 马爱元 《Journal of Central South University》 SCIE EI CAS 2014年第8期3233-3240,共8页
The technology that waste activated carbon after extracting gold is regenerated with steam under microwave heating was studied. The influence of the activation temperature, activation duration and steam flow rate on i... The technology that waste activated carbon after extracting gold is regenerated with steam under microwave heating was studied. The influence of the activation temperature, activation duration and steam flow rate on iodine adsorption value and regeneration yield of activated carbon was investigated. The response surface methodology (RSM) technique was utilized to optimize the process conditions. The optimum conditions for the preparation of activated carbon are identified to be activation temperature of 831 ℃, activation duration of 40 min and steam flow rate of 2.67 mL/min. The optimum conditions result in an activated carbon with an iodine number of 1048 mg/g and a yield of 40%, and the BET surface area evaluated using nitrogen adsorption isotherm is 1493 m2/g, with total pore volume of 1.242 cm3/g. And the pore structure of activated carbon regenerated is mainly composed of micropores and a small amount of mesopores. 展开更多
关键词 microwave heating STEAM waste activated carbon extractING response surface methodology
下载PDF
Genotoxicity and Reduced Heat Shock Protein 70 in Human Airway Smooth Muscle Cells Exposed to Cigarette Smoke Extract 被引量:1
10
作者 武小杰 罗国雄 +5 位作者 曾雪 兰立立 宁琴 徐永健 赵建平 谢俊刚 《Journal of Huazhong University of Science and Technology(Medical Sciences)》 SCIE CAS 2013年第6期827-833,共7页
Cigarette smoke is associated with the development of several diseases, such as chronic ob- structive pulmonary disease (COPD). The purpose of this study was to investigate genotoxicity and heat shock protein 70 (H... Cigarette smoke is associated with the development of several diseases, such as chronic ob- structive pulmonary disease (COPD). The purpose of this study was to investigate genotoxicity and heat shock protein 70 (Hsp70) in human airway smooth muscle cells (HASMCs) exposed to cigarette smoke extract (CSE). HASMCs was exposed to CSE with different doses for 24 h. The level of 8-hydroxydeoxyguanosine (8-OHdG) was determined by using HPLC-ECD, the DNA damage was ana- lyzed by using comet assay, and apoptosis was examined by using Annexin-FITC/PI staining. The pro- duction of Hsp70 after CSE stimulation was tested. Results indicated that CSE significantly increased the level of 8-OHdG, DNA damage and cell apoptosis, and reduced the production of Hsp70. In par- ticular, levels of Hsp70 were inversely correlated with 8-OHdG, DNA damage and cell apoptosis. It was concluded that cigarette smoke induced genotoxicity and decreased the production of cell protective protein Hsp70, which may contribute to the development of some airway diseases. 展开更多
关键词 airway smooth muscle cigarette smoke extract 8-hydroxydeoxyguanosine DNA damage heat shock protein 70
下载PDF
Optimization and Control of Extractive Distillation with Heat Integration for Separating Benzene/Cyclohexane Mixtures 被引量:3
11
作者 Li Lumin Tu Yangqin +2 位作者 Guo Lianjie Sun Lanyi Tian Yuanyu 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS 2016年第4期117-127,共11页
In this work, the extractive distillation with heat integration process is extended to separate the pressure-insensitive benzene-cyclohexane azeotrope by using furfural as the entrainer. The optimal design of extracti... In this work, the extractive distillation with heat integration process is extended to separate the pressure-insensitive benzene-cyclohexane azeotrope by using furfural as the entrainer. The optimal design of extractive distillation process is established to achieve minimum energy requirement using the multi-objective genetic algorithm, and the results show that energy saving for this heat integration process is 15.7%. Finally, the control design is performed to investigate the system's dynamic performance, and three control structures are studied. The pressure-compensated temperature control scheme is proposed based on the first two control structures, and the dynamic responses reveal that the feed disturbances in both flow rate and benzene composition can be mitigated well. 展开更多
关键词 extractive distillation heat integration optimization genetic algorithm dynamic simulation
下载PDF
Effects of Streptomyces microflavus Extract on Heat Tolerance of Tall Fescue
12
作者 王兆龙 殷朝珍 +1 位作者 孙吉雄 黄炳如 《Journal of Shanghai Jiaotong university(Science)》 EI 2005年第S1期19-25,共7页
Heat stress in summer is a major factor limiting use of cool-season grasses in Shanghai area, China. The objectives of this study were to investigate effects of a crude extract product of a new strain of Streptomyces ... Heat stress in summer is a major factor limiting use of cool-season grasses in Shanghai area, China. The objectives of this study were to investigate effects of a crude extract product of a new strain of Streptomyces microflavus (TSS) on turf performance and physiological activities of tall fescue (Festuca arundinacea) in response to heat stress. Plants of tall fescue cultivar ‘Barlexus’ were exposed to 38/33 (°C) (day/night) high temperature in growth chamber after TSS applications. High temperature induced about 3.5 fold increases of initial shoot extension rate and clipping yield (6 d) and led to quick decline of plant growth after 18 d. TSS inhibited the extent of initial increases of shoot extension rate and clipping yield and maintained a longer period of steady growth under the heat stress. TSS also decreased the decline of leaf chlorophyll content, TNC, shoot density, and turf quality induced by heat stress. The results suggested that TSS application improved turf performance under heat stress, and the greater improvement of heat tolerance was associated with higher dose of application. This positive effect on heat tolerance could be related to the decreased carbohydrate consumption and loss, and reduced decomposition of leaf chlorophyll. 展开更多
关键词 heat tolerance STREPTOMYCES microflavus extract tall FESCUE CARBOHYDRATE consumption
下载PDF
Study on the Extraction Techniques of Impatiens balsamina(Tougucao)
13
作者 Lida CHEN Yuanzhe ZHANG +3 位作者 Yuling LUO Xianmei XU Hai ZHAO Yan WU 《Agricultural Biotechnology》 CAS 2022年第4期103-106,112,共5页
[Objectives]This study was conducted to investigate the extraction method of Impatiens balsamina L.(Tougucao),and to optimize the extraction process conditions and parameters.[Methods]Different ethanol concentrations,... [Objectives]This study was conducted to investigate the extraction method of Impatiens balsamina L.(Tougucao),and to optimize the extraction process conditions and parameters.[Methods]Different ethanol concentrations,ethanol amounts and extraction time were investigated by an orthogonal test L_(9)(3^(4))and high performance liquid chromatography(HPLC),and the extraction process parameters were evaluated by the yield of extract and the content of quercetin.[Results]Under the three optimal extraction conditions of impregnation,heating reflux and ultrasound,the extract yield and quercetin contents of I.balsamina were 8.27%,9.50%,7.09%and 1.60,3.05,3.03μg/g,respectively.Heating reflux extraction and ultrasonic extraction showed higher extract yields and quercetin contents of I.balsamina,while the values were lower under the impregnation extraction conditions.The primary and secondary factors were:ethanol amount(C)>ethanol concentration(A)>extraction time(B).The optimal extraction process of I.balsamina was as follows:adding 10 times of 60%ethanol and ultrasonically extracting for 30 min.[Conclusions]The method is simple,convenient,accurate and reliable,and provides a scientific basis for the research on the extraction process of I.balsamina and its preparations. 展开更多
关键词 Impatiens balsamina IMPREGNATION heating reflux Ultrasonic extraction Orthogonal test HPLC QUERCETIN
下载PDF
水热型地热水平井取热对流传热耦合机制
14
作者 谷峰 李又武 +4 位作者 张越 高英 杨鹏 王安然 崔景云 《煤田地质与勘探》 EI CAS CSCD 北大核心 2024年第9期121-130,共10页
【目的】闭式取热技术只利用地层热量,不抽采地热水,近年来成为地热开发研究的重点领域之一,但关注储层对流对传热影响的研究相对缺乏。【方法】为了提高单井取热量,提出水热型储层水平井闭式取热工艺,增大井筒与储层的接触面积,且充分... 【目的】闭式取热技术只利用地层热量,不抽采地热水,近年来成为地热开发研究的重点领域之一,但关注储层对流对传热影响的研究相对缺乏。【方法】为了提高单井取热量,提出水热型储层水平井闭式取热工艺,增大井筒与储层的接触面积,且充分利用储层对流。建立水平井、循环水、储层互相耦合的流动传热模型,分储层自然对流、强制对流条件开展取热性能预测,揭示储层对流场、温度场演变特征。【结果和结论】结果表明:(1)储层发育与水平段垂直的强制对流可有效缓解热突破,对取热提升较为明显;与水平段平行的强制对流与自然对流取热量无明显差异。(2)与上覆地层相比,储层段对循环水温的提升占主导地位,平均每米温度提升是上覆地层的2.4倍。(3)储层对流场和温度场演变具有高度耦合特性。当储层只存在自然对流时,温度场变化范围与达西流动活跃区局限于井筒邻近区域,沿径向方向扩展;当储层发育强制对流时,温度场和对流场在水平井筒两侧呈非对称分布,低温区和低达西流速区位于对流下游方向。(4)储层温度动态恢复特征受对流条件控制。强制对流可加速对井筒周围区域热量补给,促进温度恢复,具备长年运行的条件。研究成果为水平井取热系统研究与设计提供借鉴。 展开更多
关键词 水热型地热 水平井 闭式取热 对流传热耦合 自然对流 强制对流
下载PDF
百香果果壳提取物对热应激小鼠的保护作用
15
作者 周孝琼 张海燕 +4 位作者 郭水灵 王萌萌 陆元安 周华林 王华 《中国兽医杂志》 CAS 北大核心 2024年第5期118-124,共7页
为研究百香果果壳提取物对热应激小鼠的保护作用,本试验选取健康清洁级ICR雄性小鼠40只,随机分为对照组、热应激组、低剂量组和高剂量组共4个组,每组10只。所有小鼠饲喂基础颗粒饲料,正常饮水。低剂量组和高剂量组分别按100和200 mg/(kg... 为研究百香果果壳提取物对热应激小鼠的保护作用,本试验选取健康清洁级ICR雄性小鼠40只,随机分为对照组、热应激组、低剂量组和高剂量组共4个组,每组10只。所有小鼠饲喂基础颗粒饲料,正常饮水。低剂量组和高剂量组分别按100和200 mg/(kg·bw·d)剂量灌胃百香果果壳提取物,对照组和热应激组小鼠每天灌胃等量生理盐水。持续灌胃14 d后,除对照组外,其余3个组小鼠每天热处理2 h,连续7 d,期间持续给药。试验结束时,空腹称量小鼠体重;分析小鼠体重变化;采集血液检测血清中谷氨酸氨基转移酶(ALT)、天门冬氨酸氨基转移酶(AST)、肌酐(Cr)、尿素氮(BUN)和热休克蛋白70(HSP70)生化指标,以及肿瘤坏死因子α(TNF-α)、白介素6(IL-6)、白介素2(IL-2)和γ干扰素(IFN-γ)细胞因子含量;收集小鼠肝脏和肾脏,观察其组织病理学变化。结果显示,热应激结束后,4个组小鼠体重无显著差异(P>0.05),但热应激组减重最多;与对照组比较,热应激组血清生化和细胞因子各指标均显著升高(P<0.05);与热应激组相比,低剂量组和高剂量组小鼠血清生化和细胞因子各指标均显著降低(P<0.05),小鼠肝脏和肾脏组织损伤有所减轻,且高剂量组优于低剂量组。结果表明,百香果果壳提取物对热应激小鼠具有一定的保护作用。 展开更多
关键词 百香果果壳 提取物 热应激 血清生化 细胞因子 组织病理学
下载PDF
同轴套管换热器井下换热性能实验研究
16
作者 王建辉 刘自强 +6 位作者 焦敏 刘伟 付鹏 梁迎凯 王鹏 彭国辉 袁小雪 《河北省科学院学报》 CAS 2024年第1期58-64,共7页
本文介绍了一种适用于中深层地热井的同轴套管式换热器技术,可以做到传热不传质,取热不取水,在最大限度利用深层地热的同时,不消耗深层地下水。通过实际测试单井取热量可达到118 W/m,具有取热量大、后期运行费用低等优点。实际工程应用... 本文介绍了一种适用于中深层地热井的同轴套管式换热器技术,可以做到传热不传质,取热不取水,在最大限度利用深层地热的同时,不消耗深层地下水。通过实际测试单井取热量可达到118 W/m,具有取热量大、后期运行费用低等优点。实际工程应用显示,利用“地热+”模式可以有效解决因地热井关停带来的诸多问题。利用关停的中深层地热井,只取热而不抽取地下水,有效避免中深层地热井闲置造成的资金浪费,同时可为用户提供高效清洁的能源供给。 展开更多
关键词 中深层地热井 同轴套管式换热器 取热量 实验
下载PDF
枯芩与条芩提取物对湿热型溃疡性结肠炎大鼠的药效学比较研究
17
作者 黄伟 罗雅琴 +2 位作者 于新阳 董红敬 王晓 《中国药物警戒》 2024年第3期313-318,共6页
目的比较枯芩、条芩提取物对湿热型溃疡性结肠炎(UC)大鼠模型的药效学差异。方法50只健康SD大鼠随机分为5组:正常组、模型组、枯芩组、条芩组和美莎拉嗪组,每组10只。采用高脂高糖饲料喂养+高度白酒灌胃+5%葡聚糖硫酸钠(DSS)联合诱导法... 目的比较枯芩、条芩提取物对湿热型溃疡性结肠炎(UC)大鼠模型的药效学差异。方法50只健康SD大鼠随机分为5组:正常组、模型组、枯芩组、条芩组和美莎拉嗪组,每组10只。采用高脂高糖饲料喂养+高度白酒灌胃+5%葡聚糖硫酸钠(DSS)联合诱导法,建立湿热型UC大鼠模型;各组分别于造模第1天开始灌胃给药,枯芩组、条芩组给药剂量均为5.25 g·kg^(-1)·d^(-1),美沙拉嗪组给药剂量为0.266 g·kg^(-1)·d^(-1),正常组、模型组灌服等体积生理盐水。连续给药28 d。观察大鼠一般情况;评价大鼠体质量变化和疾病活动指数(DAI)评分;称取大鼠结肠质量,量取结肠长度,并计算结肠单位长度质量;进行大鼠结肠组织HE染色和PAS染色,观察大鼠结肠组织病理学变化;Elisa法检测大鼠血清白介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)、白介素-1β(IL-1β)、转化生长因子-β_(1)(TGF-β_(1))炎症因子水平。结果与正常组比较,模型组大鼠的体质量显著降低,结肠长度显著缩短,DAI评分、结肠质量、结肠单位长度质量和血清IL-6、TNF-α、IL-1β水平均显著增加,TGF-β_(1)水平显著降低(P<0.01);结肠组织上皮层发生脱落,边缘散乱,隐窝不清晰,黏膜层有水肿,炎症细胞浸润且入侵黏膜下层,肠腺紊乱。与模型组比较,枯芩组、条芩组、美沙拉嗪组大鼠上述指标和相关症状均有明显改善(P<0.05,P<0.01);与枯芩组比较,条芩组、美沙拉嗪组在增加结肠单位长度质量、降低DAI评分、改善炎症因子水平方面均优于枯芩组(P<0.05或P<0.01)。结论枯芩、条芩提取物对湿热型UC大鼠均有较好的改善作用,且条芩优于枯芩。 展开更多
关键词 黄芩 枯芩 条芩(或子芩) 美莎拉嗪 提取物 湿热型溃疡性结肠炎 大鼠
下载PDF
地下渗流场对中深层水平井同轴套管取热性能的影响
18
作者 张杰 王贵洋 +1 位作者 尹文锋 汪浩瀚 《断块油气田》 CAS CSCD 北大核心 2024年第3期526-532,共7页
为提高中深层地热井取热效率,设计了一种水平井同轴套管换热器,考虑地下渗流场作用,研究了渗流速度、渗流方向、水平段长度等因素对水平井同轴套管换热器取热性能的影响。结果表明:水平井同轴套管换热器的出口温度和取热功率比传统垂直... 为提高中深层地热井取热效率,设计了一种水平井同轴套管换热器,考虑地下渗流场作用,研究了渗流速度、渗流方向、水平段长度等因素对水平井同轴套管换热器取热性能的影响。结果表明:水平井同轴套管换热器的出口温度和取热功率比传统垂直井同轴套管换热器提高了12.6%和42.9%;间歇开采工况下取热系统的出口温度降幅较小,且地层温度恢复更好;当含水层的渗流速度大于5×10^(-8)m/s时,系统出口温度高于无含水层,渗流速度过低不利于地热井取热;渗流方向垂直于水平段,对系统取热性能的提升效果强于与水平段同向工况;适量增加注入流量、降低注入温度、增加水平段长度,可有效提高地热井取热量。 展开更多
关键词 水平地热井 同轴套管换热器 取热效率 出口温度 地下渗流
下载PDF
干热岩压裂储层布井方式优选数值模拟
19
作者 张立刚 胡志楠 +5 位作者 范森 罗晓雷 丁河嘉 马媛媛 李庆龙 宋永扬 《地质科技通报》 CAS CSCD 北大核心 2024年第3期1-11,共11页
增强型地热系统(EGS)是从干热岩储层中提取热能的重要手段,而布井方式是影响其采热效果的关键因素,目前开展的布井方式研究较少考虑压裂储层开采模型的影响。建立了干热岩压裂储层采热的数值模型,通过不同位置的基质岩体温度下降幅度、... 增强型地热系统(EGS)是从干热岩储层中提取热能的重要手段,而布井方式是影响其采热效果的关键因素,目前开展的布井方式研究较少考虑压裂储层开采模型的影响。建立了干热岩压裂储层采热的数值模型,通过不同位置的基质岩体温度下降幅度、热提取率、采出温度和采热功率对比分析了4种不同的布井方式对EGS采热性能的影响。结果表明:相较于直井,水平井的流体热交换的面积更大,能充分开发裂缝间的热量。在生产30 a时,考虑水力压裂裂缝连通的情况下,水平井一注两采模型的采热效率最高,其在垂直于井方向上温度波及范围约690 m,基质岩体平均温度下降38.09 K,热提取率为24.42%,采热功率为3.5 MW。研究成果为提高地热系统产热量、实现干热岩高效可持续开发提供了理论参考。 展开更多
关键词 干热岩 压裂储层采热 增强型地热系统(EGS) 数值模拟 布井方式 水平井 敏感性分析
下载PDF
枯芩与条芩提取物对湿热型溃疡性结肠炎大鼠肠道菌群的影响及肠黏膜屏障的保护作用机制
20
作者 黄伟 罗雅琴 +2 位作者 于新阳 董红敬 王晓 《中国药物警戒》 2024年第4期408-414,共7页
目的探讨枯芩、条芩提取物对湿热型溃疡性结肠炎(UC)大鼠肠道菌群的影响及对肠黏膜屏障的保护作用机制。方法50只健康SD大鼠随机分为5组:正常组、模型组、枯芩组、条芩组和美莎拉嗪组,每组10只。采用高脂高糖饲料喂养+高度白酒灌胃+5%... 目的探讨枯芩、条芩提取物对湿热型溃疡性结肠炎(UC)大鼠肠道菌群的影响及对肠黏膜屏障的保护作用机制。方法50只健康SD大鼠随机分为5组:正常组、模型组、枯芩组、条芩组和美莎拉嗪组,每组10只。采用高脂高糖饲料喂养+高度白酒灌胃+5%葡聚糖硫酸钠(DSS)联合诱导法,建立湿热型UC大鼠模型;各组分别于造模第1天开始灌胃给药,枯芩组、条芩组给药剂量均为5.25 g·kg^(-1)·d^(-1),美沙拉嗪组给药剂量为0.266 g·kg^(-1)·d^(-1),正常组、模型组灌服等体积生理盐水。连续给药28 d。给药结束后,收集大鼠无菌粪便,解剖取大鼠结肠黏膜组织,进行匀浆,Elisa法检测大鼠结肠黏膜白介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)、白介素-1β(IL-1β)炎症因子水平;采用实时荧光定量聚合酶链式反应(qRT-PCR)法检测大鼠结肠组织紧密连接蛋白-1(claudin-1)、黏蛋白2(MUC2)、咬合蛋白(occludin)、闭锁小带蛋白-1(ZO-1)mRNA表达水平;采用16S rDNA测序技术检测大鼠粪便肠道菌群数量及丰度。结果与正常组比较,模型组大鼠结肠黏膜IL-6、TNF-α、IL-1β炎症因子含量均明显上升(P<0.01),Claudin-1、MUC2、Occludin、ZO-1 mRNA表达水平均明显上升(P<0.01);给药28 d后,与模型组比较,各给药组大鼠结肠黏膜IL-6、TNF-α、IL-1β水平均出现显著的降低(P<0.01),Claudin-1、MUC2、Occludin、ZO-1m RNA表达水平均出现不同程度的显著降低(P<0.05或P<0.01);与枯芩组比较,条芩组、美沙拉嗪组在降低IL-6、TNF-α、IL-1β、Claudin-1、Occludin、ZO-1 mRNA表达水平方面均优于枯芩组(P<0.05或P<0.01),对MUC2指标改善不明显,以美沙拉嗪组药效最好。肠道菌群测序结果显示,湿热型UC模型组大鼠肠道菌物种多样性及丰度降低,厚壁杆菌门(firmicutes)、拟杆菌门(bacteroidota)相对丰度明显减少(P<0.05),变形菌门(proteobacteria)相对丰度显著增加(P<0.05),枯芩组、条芩组对厚壁杆菌门、拟杆菌门明显增多(P<0.05),变形菌门明显减少(P<0.05),美沙拉嗪组调节菌群作用不明显(P>0.05)。枯芩组和条芩组也有一定的差异性,枯芩组长于增加厚壁菌门,条芩组长于增加拟杆菌门。结论枯芩、条芩可能通过回调失衡的肠道菌群,保护肠道黏膜屏障受损,抑制炎症反应,从而发挥治疗湿热型UC的作用。 展开更多
关键词 黄芩 枯芩 条芩(或子芩) 提取物 湿热型溃疡性结肠炎 肠道菌群 肠黏膜屏障 大鼠
下载PDF
上一页 1 2 50 下一页 到第
使用帮助 返回顶部