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Seasonal Variation of the Sea Surface Temperature Growth Rate of ENSO
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作者 Xinyi XING Xianghui FANG +1 位作者 Da PANG Chaopeng JI 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2024年第3期465-477,共13页
El Ni?o–Southern Oscillation(ENSO) exhibits a distinctive phase-locking characteristic, first expressed during its onset in boreal spring, developing during summer and autumn, reaching its peak towards winter, and de... El Ni?o–Southern Oscillation(ENSO) exhibits a distinctive phase-locking characteristic, first expressed during its onset in boreal spring, developing during summer and autumn, reaching its peak towards winter, and decaying over the next spring. Several studies have demonstrated that this feature arises as a result of seasonal variation in the growth rate of ENSO as expressed by the sea surface temperature(SST). The bias towards simulating the phase locking of ENSO by many state-of-the-art climate models is also attributed to the unrealistic depiction of the growth rate. In this study, the seasonal variation of SST growth rate in the Ni?o-3.4 region(5°S–5°N, 120°–170°W) is estimated in detail based on the mixed layer heat budget equation and recharge oscillator model during 1981–2020. It is suggested that the consideration of a variable mixed layer depth is essential to its diagnostic process. The estimated growth rate has a remarkable seasonal cycle with minimum rates occurring in spring and maximum rates evident in autumn. More specifically, the growth rate derived from the meridional advection(surface heat flux) is positive(negative) throughout the year. Vertical diffusion generally makes a negative contribution to the evolution of growth rate and the magnitude of vertical entrainment represents the smallest contributor. Analysis indicates that the zonal advective feedback is regulated by the meridional immigration of the intertropical convergence zone, which approaches its southernmost extent in February and progresses to its northernmost location in September, and dominates the seasonal variation of the SST growth rate. 展开更多
关键词 SST growth rate intertropical convergence zone zonal advective feedback mixed layer depth ENSO seasonal variation
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Quantifying the natural growth rate of hepatocellular carcinoma:A real-world retrospective study in southwestern China
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作者 Li Tu Hong Xie +6 位作者 Qi Li Ping-Gui Lei Pei-Ling Zhao Fan Yang Chi Gong Yuan-Lin Yao Shi Zhou 《World Journal of Hepatology》 2024年第5期800-808,共9页
BACKGROUND In recent years,approximately half of the newly diagnosed cases and mortalities attributed to hepatocellular carcinoma(HCC)have been reported in China.Despite the high incidence of HCC,there remains a pauci... BACKGROUND In recent years,approximately half of the newly diagnosed cases and mortalities attributed to hepatocellular carcinoma(HCC)have been reported in China.Despite the high incidence of HCC,there remains a paucity of data regarding the natural growth pattern and the determination of optimal surveillance intervals specific to the Chinese population.AIM To quantify the natural tumor growth pattern of HCC in regional China.METHODS A retrospective analysis was performed on patients from a single institution in Southwest China who had undergone two or more serial dynamic computed tomography or magnetic resonance imaging scans between 2014 and 2020,without having received any anti-cancer therapy.Tumor growth was assessed using tumor volume doubling time(TVDT)and tumor growth rate(TGR),with volumes measured manually by experienced radiologists.Simple univariate linear regression and descriptive analysis were applied to explore associations between growth rates and clinical factors.RESULTS This study identifies the median TVDT for HCC as 163.4 d,interquartile range(IQR)72.1 to 302.3 d,with a daily TGR of 0.42%(IQR 0.206%-0.97%).HCC growth patterns reveal that about one-third of tumors grow indolently with TVDT exceeding 270 d,another one-third of tumors exhibit rapid growth with TVDT under 90 d,and the remaining tumors show intermediate growth rates,with TVDT ranging between 3 to 9 months.CONCLUSION The identified TGRs support biannual surveillance and follow-up for HCC patients in certain regions of China.Given the observed heterogeneity in HCC growth,further investigation is warranted. 展开更多
关键词 Hepatocellular carcinoma Natural tumor growth pattern Tumor volume doubling time Tumor growth rate Realworld retrospective study
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Evaluation of Growth Rate of Invasive Aquatic Macrophytes and Contribution to Its Use in Organic Fertilizer Production: A Case of Eicchornia crassipes (Mart.) Solms, 1883 in the Lobé Creek (Littoral-Cameroon)
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作者 Roland Didier Nwamo Gordon Nwutih Ajonina +2 位作者 Tapite Chanel Yamkou Kopmou Thomas Efole Ewoukem Minette Tomedi Eyango 《Open Journal of Ecology》 2024年第7期571-583,共13页
From 20 January to 20 July 2023, a study was carried out on the Lobé Creek, a waterway subject to considerable natural and man-made pressures, with a negative impact on its biodiversity and habitats. The aim was ... From 20 January to 20 July 2023, a study was carried out on the Lobé Creek, a waterway subject to considerable natural and man-made pressures, with a negative impact on its biodiversity and habitats. The aim was to evaluate the growth rate of invasive aquatic macrophytes and their contribution to the use of organic fertilisers: a case of Eicchornia crassipes (Mart.) Solms, 1883 in the Lobé Creek (Littoral-Cameroon) with a view to its appropriate use in agronomy. The specific objective was to examine the impact of anthropogenic actions on Lobé Creek, characterise physico-chemical environment of the study area, and evaluate the growth rate of E. crassipes and its chemical composition with a view to producing an organic biofertiliser. The results show that E. crassipes represents a considerable threat to the populations of these localities. As for the physico-chemical parameters, the temperature values vary from 24 ± 1.41˚C to 26.5 ± 1.13˚C;pH from 6.3 ± 0.1 to 7.2 ± 0.07;conductivity and dissolved oxygen vary respectively from 40.7 ± 1.83 µS/cm to 19.6 ± 3.11 µS/cm and from 7.3 ± 0.14 mg/l to 5.8 ± 1.55 mg/l. Its average growth rate varies from 0.69 feet/day to 0.63 feet/day. With regard to the nitrogen, phosphorus and potassium content of water hyacinth plants, the results show that the average total nitrogen content ranges from 6.11 ± 1.59 g/kg to 5.2 ± 2.03 g/kg;total phosphorus, from 0.52 ± 0.54 g/kg to 0.88 ± 0.38 g/kg;and potassium, from 1.43 ± 0.45 g/kg to 2.61 ± 0.89 g/kg. 展开更多
关键词 Eichhornia crassipes Lobé Creek Anthropogenic Actions Physico-Chemical Environment growth rate Chemical Composition
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Effect of growth rate and diameter on microstructure and hardness of directionally solidified Ti-46Al-8Nb alloy 被引量:2
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作者 刘国怀 李新中 +6 位作者 张元 陈瑞润 苏彦庆 郭景杰 傅恒志 王昭东 王国栋 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第12期4044-4052,共9页
Bridgman-type directional solidification experiments were conducted for Ti-46Al-8Nb (mole fraction, %) alloy. The effects of the growth rate and the diameter on the microstructure, phase transition and hardness of t... Bridgman-type directional solidification experiments were conducted for Ti-46Al-8Nb (mole fraction, %) alloy. The effects of the growth rate and the diameter on the microstructure, phase transition and hardness of the alloy were investigated. The results show that with the increase of the growth rate and the decrease of the diameter, the fullyβphase solidification changes to the peritectic solidification, and the final microstructure is composed of theα2/γlamellar structure and a multiphase microstructure (B2 phase,α2/γlamellar structure) respectively, which can be attributed to the solute enrichment resulting from the decreasing diffusion and convection ability. The occurrence of peritectic reaction at high growth rate promotes the solute segregation heavily and the coarse lamellar spacing in Al-and Nb-rich region, which greatly decreases the hardness values and leads to the discontinuity of the hardness curves with the increase of the growth rate. Comparatively, the Ti-46Al-8Nb alloy has lower hardness values than the other applied TiAl-based alloys in previous studies. 展开更多
关键词 TiAl alloy directional solidification growth rate DIAMETER phase transition
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Studies on the Isolation, Identification and In Vitro Growth Rates of the Three Pathogenic Fungi from Panax notoginseng Cultivated in Wenshan Eparchy 被引量:2
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作者 王文亚 赵昶灵 +5 位作者 陈中坚 文国松 魏富刚 龙廷菊 李孙文 王崇德 《Agricultural Science & Technology》 CAS 2015年第6期1165-1171,1258,共8页
Objective] The aim of this study was to simultaneously isolate and identify the main pathogenic fungi of the root rot, black spot and round spot from the Panax notoginseng plants cultivated in Wenshan Eparchy of Yunna... Objective] The aim of this study was to simultaneously isolate and identify the main pathogenic fungi of the root rot, black spot and round spot from the Panax notoginseng plants cultivated in Wenshan Eparchy of Yunnan Province of China. [Method] The pathogenic fungi were isolated and purified by using potato dextrose agar (PDA) medium. The morphological identification was accomplished first according to the colony forms of the fungi when cultivated in vitro, then accord-ing to the symptom characteristics and colony forms of the re-isolated fungi in the reverse inoculation experiments. The molecular identification was performed accord-ing to the amplification and alignment of the internal transcribed space (ITS) se-quences of the fungi. The increases of the diameters and thickness of the colonies of the fungi cultivated in vitro were employed to indicate the growth rates of the fungi. [Results] The consistency of the colony forms and symptom characteristics and the 96%-99% similarities revealed in the ITS sequence alignments al proved that the main pathogenic fungi of the root rot, black spot and round spot of the P. notoginseng plants raised in Wenshan were Cylindrocarpon didymium, Alternaria panax and Mycocentrospora acerina, respectively. When cultivated in vitro in the same temperature, humidity and il umination, the increases of the colony diameters and thickness of C. didymium were the highest, fol owed by those of A. panax, then those of M. acerina. During different cultivation periods, the differences of the colony diameters and thickness of the three fungi al reached extremely significant level. However, at the same cultivation time, the differences of the diameters and thickness among the three fungi only reached significant level. [Conclusion] The main pathogenic fungi which result in the root rot, black spot and round spot of the P. notoginseng in Wenshan are C. didymium, A. panax and M. acerina, respec-tively. When these three diseases break out at the same time, the root rot wil spread fastest, fol owed orderly by the black spot and the round spot. 展开更多
关键词 Panax notoginseng cultivated in Wenshan Eparchy Root rot black spot and round spot Pathogenic fungus growth rate in vitro
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Supply-Side Structural Reforms and China's Potential Economic Growth Rate 被引量:10
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作者 李平 娄峰 《China Economist》 2016年第4期4-21,共18页
This paper examines the effect of supply-side structural reforms on China's potential economic growth rate in the coming decade according to the data the authors have gathered. Under the rapid growth scenario with th... This paper examines the effect of supply-side structural reforms on China's potential economic growth rate in the coming decade according to the data the authors have gathered. Under the rapid growth scenario with the implementation of supply-side structural reforms, China's potential economic growth rate will reach an average of 6.5% and 5.8% respectively in the 13th Five-year Plan (2016-2020) and 14th Five-year Plan (2021-2025) periods. These rates are 0.2 and 0.3 percentage points higher, respectively, than that under the baseline scenario with the inertia of historic trends. In implementing supply-side structural reforms, China must transform governmental functions, break monopolies, create a comprehensive competitive market environment, foster the creation of pro-innovation mechanisms, refocus on quality and efficiency, and raise capital utilization and labor productivity. 展开更多
关键词 supply-side structural reforms potential economic growth rate TFP China'seconomy
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Setting China’s Growth Target Based on the Potential Growth Rate 被引量:1
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作者 蔡昉 陆旸 《China Economist》 2015年第2期6-21,共16页
Different from other methodologies for the forecasting of China's economic growth rate, this paper forecast of future potential growth rates from the end of China's demographic dividends, and then identified it as a... Different from other methodologies for the forecasting of China's economic growth rate, this paper forecast of future potential growth rates from the end of China's demographic dividends, and then identified it as a growth target. Official promulgation of non-binding targets will guide social expectation, assist in government policy-making, boost confidence in consumers, and provide guidance for producers and investors. Based on our estimation results, we suggest that during the 13th Five-Year Plan period, a GDP growth target between 6. 5% and 7% would be appropriate. 展开更多
关键词 potential growth rate growth target demographic dividends reform dividends
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PROBABILISTIC MODELS FOR LONG FATIGUE CRACK GROWTH RATES OF LZ50 AXLE STEEL 被引量:5
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作者 赵永翔 何朝明 +3 位作者 杨冰 黄郁仲 高庆 邬平波 《应用数学和力学》 CSCD 北大核心 2005年第8期997-1002,共6页
Experimental study is performed on the probabilistic models for the long fatigue crack growth rates (da/dN) of LZ50 axle steel. An equation for crack growth rate was derived to consider the trend of stress intensity f... Experimental study is performed on the probabilistic models for the long fatigue crack growth rates (da/dN) of LZ50 axle steel. An equation for crack growth rate was derived to consider the trend of stress intensity factor range going down to the threshold and the average stress effect. The probabilistic models were presented on the equation. They consist of the probabilistic da/dN-ΔK relations, the confidence-based da/dN-ΔK relations, and the probabilistic- and confidence-based da/dN-ΔK relations. Efforts were made respectively to characterize the effects of probabilistic assessments due to the scattering regularity of test data, the number of sampling, and both of them. These relations can provide wide selections for practice. Analysis on the test data of LZ50 steel indicates that the present models are available and feasible. 展开更多
关键词 LZ50钢 疲劳长裂纹 扩展率 平均应力 门槛值 概率模型
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In situ measured growth rates of bainite plates in an Fe-C-Mn-Si superbainitic steel 被引量:5
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作者 Zhang-wei Hu Guang Xu +2 位作者 Hai-jiang Hu Li Wang Zheng-liang Xue 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2014年第4期371-378,共8页
The growth rates of bainite plates in an Fe-C-Mn-Si superbainitie steel were investigated by in situ observation. The lengthening rates of ferrite bainite during both cooling and isothermal holding processes were obse... The growth rates of bainite plates in an Fe-C-Mn-Si superbainitie steel were investigated by in situ observation. The lengthening rates of ferrite bainite during both cooling and isothermal holding processes were observed and the growth rates of bainite plates nucleating at grain boundaries, within grains and on preformed bainite were measured. It is indicated that the lengthening rates of bainite plates during the cooling and isothermal processes were different, and that the growth rates of bainite plates nucleating at different types of sites also demon- strated diversity. The bainite plates initiating at [vain boundaries during cooling grew the fastest, while the plates nucleating on preformed bainite did the slowest. However, the growth rate of the bainite plates nucleating at grain boundaries during isothermal transformation de- creased the most, whereas the bainite plates initiating within grains grew the fastest. In addition, the growth rate of ferrite bainite in the study supported the diffusion transformation mechanism of bainite from the viewooint of ~rowth rate. 展开更多
关键词 bainitic steel BAINITE growth rate cooling isothermal treatment phase transitions
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Effects of precipitates on fatigue crack growth rate of AA 7055 aluminum alloy 被引量:8
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作者 陈军洲 甄良 +1 位作者 杨守杰 戴圣龙 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2010年第12期2209-2214,共6页
The effects of precipitates on the fatigue crack growth rate of AA 7055 Al alloy subjected to different ageing treatments were investigated using transmission electron microscope and fatigue crack growth testing.The r... The effects of precipitates on the fatigue crack growth rate of AA 7055 Al alloy subjected to different ageing treatments were investigated using transmission electron microscope and fatigue crack growth testing.The results show that the T77 treated samples exhibit the lowest crack growth rate,while the crack growth rate of over-aged samples is the highest.In terms of the model based on the reversibility of dislocation motion within the plastic zone close to the crack tip,the improved crack growth resistance is attributed to many precipitates that are coherent with Al matrix in the under-aged and T77 treated samples.When the precipitate is coherent with the Al matrix,the larger the precipitate is,the slower the fatigue crack grows.The effects of grain boundary precipitates and precipitate free zone on the fatigue crack growth resistance are less significant than those of precipitates within grains of the alloy. 展开更多
关键词 7055 aluminum alloy ageing fatigue crack growth rate PRECIPITATE
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PROBABILISTIC MODELS FOR LONG FATIGUE CRACK GROWTH RATES OF LZ50 AXLE STEEL 被引量:5
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作者 ZHAO Yong-xiang(赵永翔) +9 位作者 HE Chao-ming(何朝明) YANG Bing(杨冰) HUANG Yu-zhong(黄郁仲) GAO Qing(高庆) WU Ping-bo(邬平波) 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2005年第8期1093-1099,共7页
Experimental study is performed on the probabilistic models for the long fatigue crack growth rates (da/dN) of LZ50 axle steel. An equation for crack growth rate was derived to consider the trend of stress intensity... Experimental study is performed on the probabilistic models for the long fatigue crack growth rates (da/dN) of LZ50 axle steel. An equation for crack growth rate was derived to consider the trend of stress intensity factor range going down to the threshold and the average stress effect. The probabilistic models were presented on the equation. They consist of the probabilistic da/dN-△K relations, the confidence-based da/dN-△K relations, and the probabilistic- and confidence-based da/dN-△K relations. Efforts were made respectively to characterize the effects of probabilistic assessments due to the scattering regularity of test data, the number of sampling, and both of them. These relations can provide wide selections for practice. Analysis on the test data of LZ50 steel indicates that the present models are available and feasible. 展开更多
关键词 LZ50 steel long fatigue crack growth rate average stress THRESHOLD probabilistic model
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Simple Predicting Method for Fatigue Crack Growth Rate Based on Tensile Strength of Carbon Steel 被引量:4
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作者 LI Bo HU Ji-fan +3 位作者 QIN Hong-wei MA Nuo AN Kang WANG Xin-lin 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2003年第2期58-62,共5页
Three types of fatigue tests for an annealed carbon steel containing carbon of 0.42%were carried out on smooth specimens and specimens with a small blind hole in order to investigate the fatigue crack growth law.A sim... Three types of fatigue tests for an annealed carbon steel containing carbon of 0.42%were carried out on smooth specimens and specimens with a small blind hole in order to investigate the fatigue crack growth law.A simple predicting method for crack growth rates has been proposed involving strengthσband the relation between cyclic stress and strain.The validity of proposed method has been confirmed by experiments on several carbon steels with different loadings. 展开更多
关键词 fatigue crack growth rate PREDICTION stress gradient carbon steel
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Effect of growth rate on microstructure and solute distribution of Al-Zn-Mg alloy 被引量:3
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作者 A.L.RAMIREZ-LEDESMA R.A.RODRíGUEZ-DíAZ +2 位作者 J.CHAVEZ-CARVAYAR O.ALVAREZ-FREGOSO J.A.JUAREZ-ISLAS 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2015年第5期1391-1398,共8页
An Al-5.3%Zn-5.3%Mg alloy was unidirectionally solidified to determine morphological transition and solute distribution by a modification of the Bridgman technique for crystal growth with growth rates ranging from 4-5... An Al-5.3%Zn-5.3%Mg alloy was unidirectionally solidified to determine morphological transition and solute distribution by a modification of the Bridgman technique for crystal growth with growth rates ranging from 4-500 μm/s and a temperature gradient of 25 K/cm. It was determined that growth rates from 6.5-9.5 μm/s generated a cell morphology, where the lower limit corresponds to the plane front to cellular transition and the upper limit indicates the cellular to columnar dendrite transition. The microstructures of the alloys solidified from 30 μm/s to growth rates less than 500 μm/s were mainly composed of columnar dendrites, while the microstructures solidified at growth rates greater than 500 μm/s were equiaxed. Regarding experimental results on solute distribution, a prediction of the model developed by Rappaz and Boettinger for dendrite solidification of multicomponent alloys was applied with excellent agreement. Results of solute distribution were employed to derive the precipitation fraction of τ-phase needed to increase the electrochemical properties of the alloy to be used as an Al-sacrificial anode. 展开更多
关键词 aluminum alloy unidirectional solidification growth rate solute distribution dendrite growth model
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Conservation relation of generalized growth rate in boundary layers 被引量:3
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作者 Runjie SONG Lei ZHAO Zhangfeng HUANG 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2018年第12期1755-1768,共14页
The elementary task is to calculate the growth rates of disturbances when the e;method in transition prediction is performed. However, there is no unified knowledge to determine the growth rates of disturbances in thr... The elementary task is to calculate the growth rates of disturbances when the e;method in transition prediction is performed. However, there is no unified knowledge to determine the growth rates of disturbances in three-dimensional(3 D) flows. In this paper, we study the relation among the wave parameters of the disturbance in boundary layers in which the imaginary parts of wave parameters are far smaller than the real parts.The generalized growth rate(GGR) in the direction of group velocity is introduced, and the conservation relation of GGR is strictly deduced in theory. This conservation relation manifests that the GGR only depends on the real parts of wave parameters instead of the imaginary parts. Numerical validations for GGR conservation are also provided in the cases of first/second modes and crossflow modes. The application of GGR to the eN method in 3 D flows is discussed, and the puzzle of determining growth rates in 3 D flows is clarified. A convenient method is also proposed to calculate growth rates of disturbances in 3 D flows. Good agreement between this convenient method and existing methods is found except the condition that the angle between the group velocity direction and the x-direction is close to 90?which can be easily avoided in practical application. 展开更多
关键词 generalized growth rate(GGR) boundary layer stability e^N method
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Estimating Synechococcus spp. growth rates and grazingpressure by heterotrophic nanoplankton in theEnglish Channel and the Celtic Sea 被引量:7
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作者 Ning Xiuren and Daniel Vaulot 《Acta Oceanologica Sinica》 SCIE CAS CSCD 1992年第2期255-273,共19页
-Marine chroococcoid phycoerythrin - containing Synechococcus spp. recently have been implicated as a substantial component of the photosynthetic picoplankton in the ocean. Although the importance of Synechococcus as ... -Marine chroococcoid phycoerythrin - containing Synechococcus spp. recently have been implicated as a substantial component of the photosynthetic picoplankton in the ocean. Although the importance of Synechococcus as food sources for heterotrophic nanoplankton are now recognized, the information about its cycling of biomass and diel patterns is limited and the methodology used varies according to different authors. A selective metabolic inhibitor method was used to allow simultanous estimation of both growth rates and grazing disappearance rates of Synechococcus. Results obtained in the English Channel show growth rates ranging from 0. 25 to 0. 72 d-1 with an average value of 0. 51 d -1and grazing disappearance rates ranged from 0. 21 to 0. 64 d-1 (mean = 0. 44 d-1). Offshore in the Celtic Sea of the Northeast Atlantic Ocean, both rates were lower than in the channel. The similarity between average growth and grazing rates suggests a rapid recycling of Synechococcus biomass. In diel pattern, Synechococcus grazing mortality rates were higher during the day (mean = 0. 61 d-1) than during the night (mean = 0. 21d-1) in all the experiments. A positive correlation was observed between growth rates and in situ temperature ranged from 9 to 20 ℃. Sire-fractionated experiments demonstrate that up to about 7 0 % of Synechococcus disappearance could be attributed to the grazer smaller than 2 μm in diameter. The variations of Synechococcus cell characteristics such as size and phycoerythin contents in the growth and grazing experiments were determined with a flow cytometer. The methodology recently used on estimating dynamics of Synechococcus population is reviewed. 展开更多
关键词 Estimating Synechococcus spp growth rates and grazingpressure by heterotrophic nanoplankton in theEnglish Channel and the Celtic Sea
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El Ni?o/Southern Oscillation during the 4.2 ka event recorded by growth rates of corals from the North South China Sea 被引量:2
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作者 Shaohua Dang Kefu Yu +3 位作者 Shichen Tao Tao Han Huiling Zhang Wei Jiang 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2020年第1期110-117,共8页
The 4.2 ka event that occurred during the period from 4 500–3 900 a BP was characterized by cold and dry climates and resulted in the collapse of civilizations around the world. The cause of this climatic event, howe... The 4.2 ka event that occurred during the period from 4 500–3 900 a BP was characterized by cold and dry climates and resulted in the collapse of civilizations around the world. The cause of this climatic event, however, has been under debate. We collected four corals(Porites lutea) from Yongxing Island, Xisha Islands, South China Sea, dated them with the U-series method, and measured the annual coral growth rates using X-ray technology. The dating results showed that the coral growth ages were from 4 500–3 900 a BP, which coincide well with the period of the4.2 ka event. We then reconstructed annual sea surface temperature anomaly(SSTA) variations based on the coral growth rates. The growth rate-based SSTA results showed that the interdecadal SSTA from 4 500–3 900 a BP was lower than that during modern times(1961–2008 AD). A spectral analysis showed that the SSTA variations from4 500–3 900 a BP were under the influence of El Nino-Southern Oscillation(ENSO) activities. From 4 500–4 100 a BP, the climate exhibited La Nina-like conditions with weak ENSO intensity and relatively stable and lower SSTA amplitudes. From 4 100–3 900 a BP, the climate underwent a complicated period of ENSO variability and showed alternating El Nino-or La Nina-like conditions at interdecadal time scales and large SSTA amplitudes. We speculate that during the early and middle stages of the 4.2 ka event, the cold climate caused by weak ENSO activities largely weakened social productivity. Then, during the end stages of the 4.2 ka event, the repeated fluctuations in the ENSO intensity caused frequent extreme weather events, resulting in the collapse of civilizations worldwide. Thus, the new evidence obtained from our coral records suggests that the 4.2 ka event as well as the related collapse of civilizations were very likely driven by ENSO variability. 展开更多
关键词 4.2 ka event ENSO variability SSTA coral growth rate Xisha Islands
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Growth Rate Estimates of Supergene Manganese Nodule by ^(40)Ar/^( 39)Ar Isotopic Dating 被引量:3
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作者 LiJianwei VasconcelosPM 《Journal of China University of Geosciences》 SCIE CSCD 2004年第3期312-323,共12页
Increasing world-class, high-grade, and metals-enriched supergene manganese ore deposits have been discovered in the last two decades, making them more and more economically important. However, data on the timing and ... Increasing world-class, high-grade, and metals-enriched supergene manganese ore deposits have been discovered in the last two decades, making them more and more economically important. However, data on the timing and duration of their formation are sparse, mainly due to the difficulties extracting datable minerals suited to traditional radiometric dating methods. Hollandite, cryptomelane, coronadite, todorokite, and manjiroite are common manganese oxide minerals in supergene environments. These minerals host potassium of variable amounts from 0.1 wt% to 5.0 wt% in their structural sites. This geochemical property provides possibility to date supergene manganese ores by using K-Ar and 40Ar/ 39Ar methods. In this study, we perform 40Ar/ 39Ar dating on a 7.1-cm-thick botryoidal manganese nodule from an ancient weathering profile at Mount Tabor, central Queensland, Australia. Laser microprobe incremental analyses of distinct growth bands, from the inner core through the intermediate bands to the outermost crusts of the nodule, have yielded high quality 40Ar/ 39Ar ages at 27.3 Ma, 20.9 Ma, 19.2 Ma, and 16.1 Ma, respectively. The age results permit preliminary estimates on the average growth rates of the nodule varying from 4.7×10 -3 mm/ka to 7.6×10 -3 mm/ka to 9.0×10 -3 mm/ka, from the core to the rim. Results of this study are of significance in our understanding of the mode, mechanism, process, and climatic conditions in the formation of supergene manganese ore deposits. 展开更多
关键词 supergene manganese nodule 40Ar/ 39Ar dating growth rates.
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Growth Rates of Fine Aerosol Particles at a Site near Beijing in June 2013 被引量:2
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作者 Chuanfeng ZHAO Yanan LI +2 位作者 Fang ZHANG Yele SUN Pucai WANG 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2018年第2期209-217,共9页
Growth of fine aerosol particles is investigated during the Aerosol-CCN-Cloud Closure Experiment campaign in June 2013 at an urban site near Beijing. Analyses show a high frequency (- 50%) of fine aerosol particle g... Growth of fine aerosol particles is investigated during the Aerosol-CCN-Cloud Closure Experiment campaign in June 2013 at an urban site near Beijing. Analyses show a high frequency (- 50%) of fine aerosol particle growth events, and show that the growth rates range from 2.1 to 6.5 nm h-1 with a mean value of - 5.1 nm h-1. A review of previous studies indicates that at least four mechanisms can affect the growth of fine aerosol particles: vapor condensation, intramodal coagulation, extramodal coagulation, and multi-phase chemical reaction. At the initial stage of fine aerosol particle growth, condensational growth usually plays a major role and coagulation efficiency generally increases with particle sizes. An overview of previous studies shows higher growth rates over megacity, urban and boreal forest regions than over rural and oceanic regions. This is most likely due to the higher condensational vapor, which can cause strong condensational growth of fine aerosol particles. Associated with these multiple factors of influence, there are large uncertainties for the aerosol particle growth rates, even at the same location. 展开更多
关键词 growth rate fine aerosol particle Xianghe
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Fatigue crack growth rate test using a frequency sweep method 被引量:2
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作者 Xun ZHOU Xiao-li YU 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2008年第3期346-350,共5页
Fatigue crack propagation characteristics of a diesel engine crankshaft are studied by measuring the fatigue crack growth rate using a frequency sweep method on a resonant fatigue test rig. Based on the phenomenon tha... Fatigue crack propagation characteristics of a diesel engine crankshaft are studied by measuring the fatigue crack growth rate using a frequency sweep method on a resonant fatigue test rig. Based on the phenomenon that the system frequency will change when the crack becomes large, this method can be directly applied to a complex component or structure. Finite element analyses (FEAs) are performed to calibrate the relation between the frequency change and the crack size, and to obtain the natural frequency of the test rig and the stress intensity factor (SIF) of growing cracks. The crack growth rate i.e. da/dN-AK of each crack size is obtained by combining the testing-time monitored data and FEA results. The results show that the crack growth rate of engine crankshaft, which is a component with complex geometry and special surface treatment, is quite different from that of a pure material. There is an apparent turning point in the Paris's crack partition. The cause of the fatigue crack growth is also discussed. 展开更多
关键词 Crack growth rate Residual stress Frequency sweep method Engine crankshaft RELIABILITY
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The applying of BP network in forecasting the demand and its growth rate for coal 被引量:4
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作者 纪成君 刘宏超 《Journal of Coal Science & Engineering(China)》 2001年第1期102-107,共6页
Based on the statistical data from 1975 to 1997, we forecast the growth rate of coal consuming and the quantity in coming decade with the BP neuron network in the article.
关键词 the quantity of coal consuming the growth rate of consuming BP neuron network forecasting
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