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无花空绕枝
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作者 鱼幼薇 流浪猫(图) 《布老虎青春文学》 2010年第16期1-3,共3页
艳静如笼月.香寒未逐风。桃花徒照地.终被笑妖红。暖意微醺.缕缕香风盈袖。满山粉白的桃花.妖娆盛开。去年今日.我便是在这里.遇上了他。
关键词 《无花空绕枝》 散文 文学 鱼幼薇
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Temporal-spatial Distribution Model of Cold Chain Logistics for Vegetables
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作者 陈绍慧 张鹏 +1 位作者 鲁晓翔 李江阔 《Agricultural Science & Technology》 CAS 2012年第5期1115-1118,共4页
[Objective] The aim was to study on temporal-spatial distribution model of cold chain logistics for vegetables. [Method] Broccoli was taken as an example. Detailedly, time-space distribution model of cold chain logist... [Objective] The aim was to study on temporal-spatial distribution model of cold chain logistics for vegetables. [Method] Broccoli was taken as an example. Detailedly, time-space distribution model of cold chain logistics for broccoli was proposed from standpoints of costs and benefits based on changes of time and space, and a comprehensive evaluation was made on timeliness, efficiency, risks, added- value of products and satisfaction of information in cold-chain logistics. [Result] The efficiency of cold chain logistics for vegetable can be greatly improved by temporal- spatial distribution model of cold chain logistics. [Conclusion] Costs and benefits of vegetables in temporal-apstial distribution could be evaluated by the model. 展开更多
关键词 VEGETABLE Cold-chain logistics Temporal-spatial distribution BROCCOLI
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在最美的年华,做最好的自己
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《北方牧业》 2019年第10期3-3,共1页
总以为来日方长,蓦然回首,许多时光已被岁月的长河搁浅在流年彼岸,只能成为记忆长巷里或浅或深的印迹,又似坠入泥土的落花,再也无法飞回岁月的枝头,娇艳如初。有花堪折直须折,莫待无花空折枝。莫在最美的年华,辜负最好的自己。也许,我... 总以为来日方长,蓦然回首,许多时光已被岁月的长河搁浅在流年彼岸,只能成为记忆长巷里或浅或深的印迹,又似坠入泥土的落花,再也无法飞回岁月的枝头,娇艳如初。有花堪折直须折,莫待无花空折枝。莫在最美的年华,辜负最好的自己。也许,我们不是灼灼红叶中最绚烂的那一枚。 展开更多
关键词 蓦然回首 直须 来日方长 落花 花空 长河 长巷
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Daily Ambrosia Pollen Concentration in the Air of Ankara,Turkey (1990-1999) 被引量:4
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作者 Ayse KAPLAN Nazmiye SAKIYAN Nmǖnevver PINAR 《Acta Botanica Sinica》 CSCD 2003年第12期1408-1412,共5页
The airborne ragweed pollen spectrum was investigated in the air of Ankara, Turkey for aperiod of ten years (1990-1999) using a Burkard seven-day volumetric recording trap. In our study period,long distance transporte... The airborne ragweed pollen spectrum was investigated in the air of Ankara, Turkey for aperiod of ten years (1990-1999) using a Burkard seven-day volumetric recording trap. In our study period,long distance transported Ambrosia pollen has been registered. Daily pollen levels varied from low to highin Burge抯 system. In last three years, the pollen concentration of Ambrosia showed a clear increasingtendency. Our results prove that ragweed pollen may be an important threat for ragweed sensitive patientsin Ankara city in near future. 展开更多
关键词 AMBROSIA RAGWEED long distance transport ANKARA TurkeyAySe KAPLAN1* Nazmiye SAKIYAN2 N Muevver PINAR2..‘s
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SURVEY OF AIRBORNE POLLEN IN HUBEI PROVINCE OF CHINA 被引量:3
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作者 Guang-hui Liu Rong-fei Zhu Wei Zhang Wen-jing Li Zhong-xi Wang Huan Chen 《Chinese Medical Sciences Journal》 CAS CSCD 2008年第4期212-217,共6页
Objective To study the genera and seasonal distribution of airborne pollen in Hubei province of China, and its relationship with pollinosis. Methods From November 2003 to October 2004, an airborne pollen investigation... Objective To study the genera and seasonal distribution of airborne pollen in Hubei province of China, and its relationship with pollinosis. Methods From November 2003 to October 2004, an airborne pollen investigation was performed in 16 chosen areas in 12 cities of Hubei province using gravity sedimentation technique. Meanwhile, univalent skin prick tests of pollens were performed and the invasion season was studied on 2 300 patients with pollinosis. Among them, 352 cases underwent the airway responsiveness measurements, and the correlation between airway responsiveness and results of pollen count was analyzed. Results A total of 61 pollen genera were observed and 257 520 pollens were collected. The peak of airborne pollen distribution occurred in two seasons each year: spring (March and April) and autumn (from August to October). The attack of pollinosis corresponded to the peak of pollen distribution. There was a significantly negative relationship between the provocation dose causing a 20% decrease of forced expiratory volume in one second (FEV1) from baseline and airborne pollen concentration (r = -0.6829, P < 0.05). Conclusion This study provides useful information for airborne pollen epidemiology of Hubei province, and it provides important insights to clinical prevention, diagnosis, and treatment of pollen-related allergic diseases. 展开更多
关键词 airborne pollen POLLINOSIS airway responsiveness
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Implications of tree species–environment relationships for the responsiveness of Himalayan krummholz treelines to climate change 被引量:3
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作者 Niels SCHWAB Udo SCHICKHOFF +5 位作者 Birgit BURZLE Michael MULLER Jurgen BOHNER Ram Prasad CHAUDHARY Thomas SCHOLTEN Jens OLDELAND 《Journal of Mountain Science》 SCIE CSCD 2017年第3期453-473,共21页
Climate warming is expected to advance treelines to higher elevations. However, empirical studies in diverse mountain ranges give evidence of both advancing alpine treelines as well as rather insignificant responses. ... Climate warming is expected to advance treelines to higher elevations. However, empirical studies in diverse mountain ranges give evidence of both advancing alpine treelines as well as rather insignificant responses. In this context, we aim at investigating the sensitivity and responsiveness of the near-natural treeline ecotone in Rolwaling Himal, Nepal, to climate warming. We analysed population densities of tree species along the treeline ecotone from closed forest stands via the krummholz belt to alpine dwarf shrub heaths (3700-4200 m) at 50 plots in 2013 and 2014. We quantified species - environment relationships, i.e. the change of environmental conditions (e.g., nutrient and thermal deficits, plant interactions) across the ecotone by means of redundancy analyses, variation partitioning and distance-based Moran's eigenvector maps. In particular, we focus on explaining the high competitiveness of Rhododendron campanulatum forming a dense krummholz belt and on the implications for the responsiveness of Himalayan krummholz treelines to climate change. Results indicate that treeline trees in the ecotone show species-specific responses to the influence of environmental parameters, and that juvenile and adult tree responses are modulated by environmental constraints in differing intensity. Moreover, the species - environment relationships suggest that the investigated krummholz belt will largely prevent the upward migration of other tree constrain the future response species and thus of Himalayan krummholz treelines to climate warming. 展开更多
关键词 HIMALAYA Nepal Population structure Rhododendron campanulatum Spatial patterns Species-environment relationships Stand density Variation partitioning
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On Spatial Distribution Pattern of Broccoli Clubroot Disease and and the Sampling Technique
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作者 钟列权 王会福 余山红 《Agricultural Science & Technology》 CAS 2015年第12期2715-2719,共5页
[Objective] To further improve the prediction and forecast and continuous control ability of broccoli clubroot disease. [Methods] The spatial distribution pattern of diseased or infected plants was analyzed using the ... [Objective] To further improve the prediction and forecast and continuous control ability of broccoli clubroot disease. [Methods] The spatial distribution pattern of diseased or infected plants was analyzed using the least square method, fre- quency distribution, aggregation index, m*-m regression analysis and Taylor's pow- er law model. [Result] The field distribution of broccoli plants with clubroot disease tended to be aggregated distribution, m'-m regression analysis showed that the el- ementary composition of the spatial distribution of diseased or infected plants was individual colony, the individuals attracted each other; the disease had obvious dis- ease focus in the field, and the individual colony showed uniform distribution pattern in the field. Taylor's power law showed that the spatial pattern of individual dis- eased or infected plant with clubroot disease tended to be uniform distribution with the increase of the density. On the basis of this, Iwao optimal theoretical sampling model and sequential sampling model were established, namely N =273.954 1/m- 59.698 5, To (N)=0.368 4N±1.926 8√N, respectively, it meant that when surveying N plants, if the accumulative incidence rate exceeded upper bound, the field can be set as control object; if the accumulative incidence rate didn't reach lower bound, it can be set as uncontrol field; if the accumulative incidence rate was between upper bound and lower bound, it should be surveyed continuously until the maximum sample size (mo=0.368 4) appeared, that was, the disease incidence was 15%, so the sampling number should be 684 plants. [Conclusion] The research results had very important instructive meaning for disease control. 展开更多
关键词 Broccoli clubfoot disease Spatial distribution pattern The optimal theo- retical sampling model Sequential sampling model Sampling number
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Seismic Design Loads of Truss Arch Frames with Ceilings subjected to Vertical and Horizontal Earthquake Motions
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作者 Koichiro Ishikawa 《Journal of Mathematics and System Science》 2017年第11期308-315,共8页
Spatial structures such as a gymnasium and an exhibition hall often use ceilings because of enhancing sound effects and reducing heating bills. Although the ceiling members fell down on a large scale due to the seismi... Spatial structures such as a gymnasium and an exhibition hall often use ceilings because of enhancing sound effects and reducing heating bills. Although the ceiling members fell down on a large scale due to the seismic motion according to the past great earthquake disaster reports, structural engineers particularly do not carry out the seismic design. The study gives structural engineers the equivalent static loads for the design of the earthquake-proof design of the ceiling system. In particular, it is significant to investigate the dynamic behavior and the applied seismic loads for the complicated vibration of the long span arch building structures with RC columns. 展开更多
关键词 Truss arch frame RC column Knee brace Vertical and horizontal earthquake motions Earthquake-proof design Equivalent static load Dominant natural mode
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Ambrosia Artemisfifolia L. Invasive and Allergic Weed Species on the Territory of Novi Sad 被引量:1
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作者 B. Konstantinovie M. Meseldzija +1 位作者 Bo. Konstantinovie N. Mandie 《Journal of Agricultural Science and Technology》 2011年第3期304-309,共6页
During three years lasting studies on the territory of the city of Novi Sad, terrain studies of Ambrosia artemisiifolia L. distribution as well as mapping were performed on regulated and disordered green areas and on ... During three years lasting studies on the territory of the city of Novi Sad, terrain studies of Ambrosia artemisiifolia L. distribution as well as mapping were performed on regulated and disordered green areas and on arable areas. For mapping of ragweed distribution, partially modified method of Braun-Blanquet was used, and data processing was perfomed by specially designed program Ambrosia Spot Marker. Monitoring of this species was also done because of the occurrence of retrovegetation after mowing. During vegetation period, this allergenic weed species was controlled by multiple mowing, and rough ruderal sites outside settlements were treated by glyphosate at a rate of 1.2 kg ha^-1 -2.4 kg ha^-1. The study comprehended also monitoring of pollen concentrations in the air by Rotorod pollen sampler spore collector. A. artemisiifolia L. was established in 21 city zones on over 200 localities, on the banks of the river Danube, in Petrovaradin and Sremski Karlovci. Recommended mechanical measures such as mowing, drilling in the phase of germination, and chemical control measures, resulted in significant reduction ofA. artemisiifolia L. In the second half of the August 2009 the highest number of pollen grains was found in the amount of 783 pollen grains per m3 of air. 展开更多
关键词 Ambrosia artemisiifolia L. INVASIVE allergenic weed pollen.
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Computational Simulation of Complex Structure Fancy Yarns
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作者 马建伟 周奉磊 +1 位作者 陈韶娟 许文娜 《Journal of Donghua University(English Edition)》 EI CAS 2007年第2期244-247,共4页
A study is reported for mathematical model and simulative of complex structure fancy yams. The investigated complex structure fancy yams have a multithread structure composed of three components core, effect, and bind... A study is reported for mathematical model and simulative of complex structure fancy yams. The investigated complex structure fancy yams have a multithread structure composed of three components core, effect, and binder yams. In current research the precondition was accepted that the cross-sections of the both two yams of the effect intermediate product in the complex structure fancy yam remain the circles shaped, and this shape does not change during manufacturing of the fancy yam. Mathematical model of complex structure fancy yarn is established based on parameter equation of space helix line and computer simulative is further carried out using the computational mathematical tool Matlab 6.5. Theoretical structure of fancy yam is compared with an experimental sample. The simulative system would help for further the set of informative in designing of new assortment of the complex structure fancy yarns and prediction of visual effects of fancy yams in end-use fabrics. 展开更多
关键词 fancy yarn mathematical model space helix computer simulation
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Size Distributions and Source Function of Sea Spray Aerosol over the South China Sea 被引量:1
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作者 CHU Yingjia SHENG Lifang +3 位作者 LIU Qian ZHAO Dongliang JIA Nan KONG Yawen 《Journal of Ocean University of China》 SCIE CAS 2016年第4期569-576,共8页
The number concentrations in the radius range of 0.06 – 5 μm of aerosol particles and meteorological parameters were measured on board during a cruise in the South China Sea from August 25 to October 12, 2012. Effec... The number concentrations in the radius range of 0.06 – 5 μm of aerosol particles and meteorological parameters were measured on board during a cruise in the South China Sea from August 25 to October 12, 2012. Effective fluxes in the reference height of 10 m were estimated by steady state dry deposition method based on the observed data, and the influences of different air masses on flux were discussed in this paper. The number size distribution was characterized by a bimodal mode, with the average total number concentration of(1.50 ± 0.76)×10~3 cm^(-3). The two mode radii were 0.099 μm and 0.886 μm, both of which were within the scope of accumulation mode. A typical daily average size distribution was compared with that measured in the Bay of Bengal. In the whole radius range, the number concentrations were in agreement with each other; the modes were more distinct in this study than that abtained in the Bay of Bengal. The size distribution of the fluxes was fitted with the sum of log-normal and power-law distribution. The impact of different air masses was mainly on flux magnitude, rather than the shape of spectral distribution. A semiempirical source function that is applicable in the radius range of 0.06 μm 展开更多
关键词 Aerosol aerosol fitted meteorological radius cruise humidity magnitude maritime applicable
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The Effect of Air Pollution on Chenopodium album L. Pollen Structure
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作者 Leila Amjad Mahsa Shafighi 《Journal of Agricultural Science and Technology(A)》 2012年第1期143-148,共6页
Air pollution is harm and discomfort to human or other living organisms, it also causes damage to the environment. The aim of this project was to study the effect of air pollutions on structure and pollen grains devel... Air pollution is harm and discomfort to human or other living organisms, it also causes damage to the environment. The aim of this project was to study the effect of air pollutions on structure and pollen grains development in Chenopodium album. Anthers of Chenopodium album L. were collected at different stages of development from control (less polluted) and polluted areas (mainly SO2, NO2, CO and APM). Structure and development of pollen grains were studied and compared. The effects of pollution on pollen structure was investigated under Light and Scanning electron microscopy and the results showed that when pollen grains were exposed to polluted air they became abnormality in form and covered with large amounts of pollutants compared to control ones. Pollen abnormalities were seen as irregularity, shrinkage, thinning and breakage of the exine. Cellular material release was induced also. The data presented suggest that prolonged exposures of plants to air pollution may cause different biological effects at the cellular tissue and organ levels. 展开更多
关键词 Air pollution pollen grains Chenopodium album L
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Effect of Cement Dust Pollution on the Yield and Quality of Ficuscarica L. Fruits
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作者 Amal Mohamed Abdel-Rahman 《Journal of Life Sciences》 2012年第3期276-282,共7页
The present study was carried out on Ficuscarica L. cultivated in the northwestern desert of Egypt. Plant materials (leaves and fruits) were collected from three polluted locations at a distance of 500-700, 1,000-1,... The present study was carried out on Ficuscarica L. cultivated in the northwestern desert of Egypt. Plant materials (leaves and fruits) were collected from three polluted locations at a distance of 500-700, 1,000-1,250 and 3,000-3,500 m respectively away from the cement factory at EI-Hammam city, and a location of relatively clean air considered a control at 5,000-6,000 m away from this factory. The deposit cement dust washed from the surface leaf area of plant study was found to be 4.96, 4.21, 0.51 and 0.29 lag/cm2 at the four locations, respectively. Cement in more polluted locations increased mortality of young branches leading to a reduction in the height and yield of fig trees. The deposition of cement pollutants tothe loamy sandy soil of the present study alteredsoil chemical characteristics. The results showed that, biomass of fruits/tree, number of branches/tree and number of fruits/branch in polluted locations were significantly lower than those of the control one. Cement dust decreased leaf total chlorophyll content leading to a reduction in the economic yield (up to 50%). Metabolic constituents (carbohydrates, proteins, amino acid and proline) and essential elements (Fe, Mg, Na, Ca, and K) were studied in two types of fruits on fig trees (mature and premature). Thallium as a toxic metal was predicted in edible mature fruits, and the results showed that the concentration of thallium parts per billion (ppb) in polluted locations was significantly higher than those of the control one. The results revealed that fruits of fig plants at polluted sites showed quantitative and qualitative deteriorations. 展开更多
关键词 Ficuscarica L. cement dust metabolic constituents THALLIUM yield.
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Spatio-temporal relationships of Clania miniscula (Lepidoptera: Psychidae) and garden spider (Araneae: Araneidae) in sasanqua orchard
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作者 CAO Chuan-wang BI Shou-dong +1 位作者 FANG Guo-fei DING Yu-zhou 《Journal of Agricultural Science and Technology》 2009年第1期35-41,共7页
Spatio-temporal relationship of the phytophagons Clania miniscula (Butler) and garden spiders was examined through analysis of their niche and distribution as they occur in sasanqua orchard in Southern Anhui, China ... Spatio-temporal relationship of the phytophagons Clania miniscula (Butler) and garden spiders was examined through analysis of their niche and distribution as they occur in sasanqua orchard in Southern Anhui, China from June 2003 to May 2004. The dynamic relationships between Clania minuscula and garden spiders were seasonal in time and space. Spatio-temporal niche breadth was high for the two groups, ranging from 0.57 to 0.98; niche overlap was also high between the two groups from 0.76 to 0.96 during the seasons of June 2003 to May 2004. Geostatistical results indicated that Clania minuscula and garden spiders were aggregated during the emergence periods. The pest Clania minuscula was spatially dependent to a range from 33.48 to 46.84 m while spatial dependence from 30.93 to 51.11 m for garden spiders. The correlation analysis of distribution maps further illustrate the distribution of garden spiders always coincided with that of Clania minuscula. These results showed spatio-temporal synchrony of Clania minuscula and garden spiders at different periods. Adequate knowledge of spatio-temporal correlation between Clania minuscula and garden spiders contributed to provide information for biocontrol at different periods in sasanqua orchard. 展开更多
关键词 spatio-temporal relationship niche GEOSTATISTICS Clania miniscula (Butler) garden spiders sasanqua orchard
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Firework Induced Large Increase in Trace Gases and Black Carbon at Dibrugarh, India
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作者 Binita Pathak Chandrakala Bharali Jhuma Biswas Pradip Kumar Bhuyan 《Journal of Earth Science and Engineering》 2013年第8期540-544,共5页
Religious, occasional and annual fire work festivals worldwide are found to introduce high concentrations of pollutant gases and particulate matter into the atmosphere. These in turn alters the air quality of a region... Religious, occasional and annual fire work festivals worldwide are found to introduce high concentrations of pollutant gases and particulate matter into the atmosphere. These in turn alters the air quality of a region in the short and long time scales and affect human health adversely. The effect of fireworks on short-term variation in air quality of an urban location Dibrugarh, set amidst the rural environment of north-east India, was assessed from the ambient concentrations of 03, SO2, NOx, CO and BC (black carbon) during the Diwali festival during Nov. 13-14, 2012. The firework activity in general peaks during evening to midnight hours. Substantial increase in concentrations of O3, SO2, NOx, CO and BC was observed during the peak hours of firework activity (16:00 h to 22:00 h) in the Day 1 and Day 2 of the Diwali festival. However, the increase in concentrations from the background level was found to be highest on the post-Diwali day due to their accumulation in the atmosphere. The firework activity has not affected the regular diurnal pattern of the measured species during this episode. 展开更多
关键词 O3 NOx FIREWORK black carbon air quality
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Assessment of natural radioactivity levels in Yemen rocks
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作者 Haman Mohamed Diab Abou Bakr A. Ramadan Abdel-Hamed Osman 《Journal of Environmental Science and Engineering》 2009年第7期58-63,共6页
Studies on radiation level and radionuclide distribution in Yemen were studied. The samples were collected from eight locations: Ma'rib, A1 Jawf, Sana'a, Dhamar, Amran, Ibb, Al Bayda and Al Dalea. The purpose of th... Studies on radiation level and radionuclide distribution in Yemen were studied. The samples were collected from eight locations: Ma'rib, A1 Jawf, Sana'a, Dhamar, Amran, Ibb, Al Bayda and Al Dalea. The purpose of this study is to provide a baseline map of radioactivity background levels in the investigated area and this study will be used as reference information to assess any change in the radioactive background level due to geological processes. The highest values of 22~ and 2~l'h concentrations (8797.2 and 24984.1 Bq.kg"l, respectively) were observed at A1 Jawf, region, whereas the highest average value of 40K concentration was 1561.9 Bq.kg-1. The investigation of the geological maps of the area under study showed that the surface rock outcrops consist mainly of granites, diorite, granodiorite, gneisses, and schists. All these rock types arc known to be rich in radioactive materials, which are considered natural sources for gamma radiation. The low mdiological background characterizing some Yemeni rocks could be attributed to nature of these rocks which consist of lime stone (sands and gravels). The absorbed dose rate in air was found to be in the range between 5.40 and 45.11 nGy.h-1 depending on the geological features, and radium equivalent activity concentration was found in the range between 29.57 and 71.85 Bq.kg-1. Also the representative extcmal hazard index values for the corresponding samples were also estinlated and given. 展开更多
关键词 natural radioactivity gamma radiation soil ROCK elemental concentration POTASSIUM THORIUM URANIUM
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Macro-meso fracture evolution mechanism of hollow cylindrical granite with different hole diameters under conventional triaxial compression
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作者 ZENG Lin-hai ZHANG Dao-bing +2 位作者 ZHANG Jia-hua ZHANG Biao YIN Hua-dong 《Journal of Central South University》 SCIE EI CAS 2024年第9期3281-3294,共14页
In order to study and analyze the stability of engineering rock mass under non-uniform triaxial stress and obtain the evolution mechanism of the whole process of fracture,a series of conventional triaxial compression ... In order to study and analyze the stability of engineering rock mass under non-uniform triaxial stress and obtain the evolution mechanism of the whole process of fracture,a series of conventional triaxial compression tests and three-dimensional numerical simulation tests were carried out on hollow granite specimens with different diameters.The bearing capacity of hollow cylindrical specimen is analyzed based on elasticity.The results show that:1)Under low confining pressure,the tensile strain near the hole of the hollow cylindrical specimen is obvious,and the specimen deformation near the hole is significant.At the initial stage of loading,the compressive stress and compressive strain of the specimen are widely distributed.With the progress of loading,the number of microelements subjected to tensile strain gradually increases,and even spreads throughout the specimen;2)Under conventional triaxial compression,the cracking position of hollow cylinder specimens is concentrated in the upper and lower parts,and the final fracture mode is generally compressive shear failure.The final fracture mode of complete specimen is generally tensile fracture.Under high confining pressure,the tensile cracks of the sample are concentrated in the upper and lower parts and are not connected,while the cracks of the upper and lower parts of the intact sample will expand and connect to form a fracture surface;3)In addition,the tensile crack widths of intact and hollow cylindrical specimens under low confining pressure are larger than those under high confining pressure. 展开更多
关键词 hollow-cylinder granite fracture mechanism hole size compressed deformation crack propagation
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同学们,六月,你们将迎战中考
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作者 李佳君 《招生考试通讯(中考版)》 2018年第5期46-46,共1页
有人懊悔过去,如果你仍虚度,将来又会为初三而后悔,莫待无花空折枝。珍惜光阴、勿贪玩,它会毁你青春及美好人生。莫学花盼春,要做燕衔泥。船要扬帆起航,鹰要展翅翱翔。目标使你不再困惑、停滞不前。理想不付诸行动,只能望梅止渴。蓝图已... 有人懊悔过去,如果你仍虚度,将来又会为初三而后悔,莫待无花空折枝。珍惜光阴、勿贪玩,它会毁你青春及美好人生。莫学花盼春,要做燕衔泥。船要扬帆起航,鹰要展翅翱翔。目标使你不再困惑、停滞不前。理想不付诸行动,只能望梅止渴。蓝图已绘,奋斗方能实现;已经起跑,拼搏可达终点。分秒必争,可拥有未来;坚持不懈,将受益终生。学业有成,贵在自觉。愿孤灯伴你夜读,愿鸡啼催你早起。本领过硬,以实力来应战;不断进取,化理想为现实。 展开更多
关键词 贵在 花空 学业有成 理想 折枝 青春 孤灯 本领
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Energy conversion characteristics of reciprocating piston quasi- isothermal compression systems using water sprays 被引量:6
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作者 jia guanwei cai maolin +1 位作者 xu weiqing shi yan 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2018年第2期285-298,共14页
Air compressors are vital and have numerous industrial applications. Approximately 8% of the annual operating electricity consumption in industrial countries is constituted by due to the use of air compressors. Becaus... Air compressors are vital and have numerous industrial applications. Approximately 8% of the annual operating electricity consumption in industrial countries is constituted by due to the use of air compressors. Because the poor heat transfer to the environment in the rapid compression process, the compression is non-isothermal, the efficiency of compressors is restricted. To improve their efficiency and achieve isothermal compression, this study proposes energy conversion reciprocating piston quasiisothermal compression using a water spray. First, a mathematical model of a reciprocating piston compressor with water sprays was established. Through experimental investigation and simulations, the mathematical model was validated. The energy conversion characteristics of the reciprocating piston compressor were then studied. To reduce compression power and enhance compression efficiency, it was first discovered that the critical parameters were the input pressure of the driving chamber, water spray mass, and compression volume ratio, which were then evaluated thoroughly. The higher the inlet pressure of the driving chamber, the faster the air compression velocity. Additionally, the compression efficiency was elevated as the water spray mass was gradually increased for a given compression volume ratio. When the compression volume ratio was increased from 2 to 3,the compression power increased from 172.7 J/stroke to 294.2 J/stroke and the compression efficiency was enhanced from 37.3%(adiabatic) to 80.6%. This research and its performance analysis can be referred to during the parameter design optimisation of reciprocating piston quasi-isothermal compression systems using water sprays. 展开更多
关键词 water spray cooling quasi-isothermal compression compression power compression efficiency
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Spatial and Temporal Distribution Characteristics of Flower-viewing Tourism and Its Influencing Factors in China 被引量:1
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作者 WANG Lu ZHOU Linjie +1 位作者 TANG Chengcai NING Zhizhong 《Journal of Resources and Ecology》 CSCD 2022年第4期746-758,共13页
Despite the rapid development of flower-viewing tourism in China in recent years,there is almost no systematic research on it.Therefore,this study analyzes the spatial and temporal distribution characteristics of flow... Despite the rapid development of flower-viewing tourism in China in recent years,there is almost no systematic research on it.Therefore,this study analyzes the spatial and temporal distribution characteristics of flower-viewing tourism and its influencing factors in China using the spatial statistical analysis methods and the geographic detector method.The study uses the Point-of-Interest data of flower-viewing tourist attractions from networks such as Qunar and Ctrip,the flower observation data from China Phenological Observation Network,Chinese network news,and Weibo,and the statistical data from yearbooks.The results are as follows:1)The spatial attribution type of flower-viewing tourism in China is aggregated into areas,including two high-density aggregated areas,three medium-density aggregated areas,and one general-density aggregated area.Furthermore,five major types of flower-viewing tourist attractions have formed several aggregated areas.2)The time of flower viewing in China starts from about February and lasts about eight months till October each year.Florescence and flowering time of different ornamental flowers in different regions are different.3)The spatial and temporal distribution characteristics of flower-viewing tourism in China are mainly affected by ornamental flower phenology,spatial distribution characteristics of flower-viewing resources,regional permanent population size,youth population size,female population size,regional GDP,and added value of the tertiary sector.These conclusions clarify the spatial and temporal distribution characteristics of flower-viewing tourism and its influencing factors in China.They could provide a scientific basis and useful reference for the coordination and sustainable development of regional flower-viewing tourism in China. 展开更多
关键词 flower-viewing tourism influencing factors spatial and temporal distribution characteristics tourist attractions
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