Flowers or inflorescences often deploy various signals, including visual, olfactory, and gustatory cues,that can be detected by their pollinators. In many plants,these cues and their functions are poorly understood.De...Flowers or inflorescences often deploy various signals, including visual, olfactory, and gustatory cues,that can be detected by their pollinators. In many plants,these cues and their functions are poorly understood.Deciphering the interactions between floral cues and pollinators is crucial for analyzing the reproductive success of flowering plants. In this study, we examined the composition of the fetid floral scents produced by several Stemona species, including nine S. tuberosa populations from across China, using dynamic headspace adsorption, gas chromatography, and mass spectrometry techniques. We compared variations in floral phenotype,including floral longevity, nectar rewards, pollinator behavior, and flower length and color among the Stemona species. Of the 54 scent compounds identified,the major compounds include fetid dimethyl disulfide,dimethyl trisulfide, 1-pyrroline, butyric acid, p-cresol,isoamyl alcohol, and indole. We detected striking differentiation in floral scent at both the species and population level, and even within a population of plants with different colored flowers. Floral characteristics related to sapromyophily and deceptive pollination,including flower color mimicking livor mortis and a lack of nectar, were found in five Stemona species, indicating that Stemona is a typical sapromyophilous taxon. Species of this monocot genus might employ evolutionary tactics to exploit saprophilous flies for pollination.展开更多
The international journal Sciences in Cold and Arid Regions,is devoted to publishing the latest research achievements in processes and the patterns of the Earth surface system in cold and arid regions.Research in cold...The international journal Sciences in Cold and Arid Regions,is devoted to publishing the latest research achievements in processes and the patterns of the Earth surface system in cold and arid regions.Research in cold regions emphasize particularly on the cold-region-characterized physical,chemical and biological processes and their interactions,and on the response of cryosphere to global change and human activities as well as their effects on environment and the acclimatizable strategies.展开更多
Adobe After Effects因其可以高效且精确地创建无数种引人注目的动态图形和震撼人心的视觉效果在影视后期合成处理中有着普遍的应用。而在通过After Effects进行创作的过程中,各种插件又让人们如虎添翼。在这里,笔者总结了一个利用AE第...Adobe After Effects因其可以高效且精确地创建无数种引人注目的动态图形和震撼人心的视觉效果在影视后期合成处理中有着普遍的应用。而在通过After Effects进行创作的过程中,各种插件又让人们如虎添翼。在这里,笔者总结了一个利用AE第三方插件——Trapcode Particular来制作一个看上去具有一种"往事随风"意味的特效制作方法。展开更多
The burning of crop residues emits large quantities of atmospheric aerosols.Published studies have developed inventories of emissions from crop residue burning based on statistical data.In contrast,this study used sat...The burning of crop residues emits large quantities of atmospheric aerosols.Published studies have developed inventories of emissions from crop residue burning based on statistical data.In contrast,this study used satellite-retrieved land-cover data(1 km×1 km)as activity data to compile an inventory of atmospheric pollutants emitted from the burning of crop residues in China in 2015.The emissions of PM10,PM2.5,VOCs,NOx,SO2,CO,and NH3 from burning crop straw on nonirrigated farmland in China in 2015 were 610.5,598.4,584.4,230.6,35.4,3329.3,and 36.1 Gg(1 Gg=109 g),respectively;the corresponding emissions from burning paddy rice residues were 234.1,229.7,342.3,57.5,57.5,1122.1,and 21.5 Gg,respectively.The emissions from crop residue burning showed large spatial and temporal variations.The emissions of particulate matter and gaseous pollutants from crop residue burning in nonirrigated farmland were highest in east China,particularly in Shandong,Henan,Anhui,and Sichuan provinces.Emissions from burning paddy rice residue were highest in east and central China,with particularly high levels in Shandong,Jiangsu,Zhejiang,and Hunan provinces.The monthly variations in atmospheric pollutant emissions were similar among different regions,with the highest levels observed in October in north,northeast,northwest,east,and southwest China and in June and July in central and south China.The developed inventory of emissions from crop residue burning is expected to help improve air quality models by providing high-resolution spatial and temporal data.展开更多
随着影视制作技术的快速发展,一部部令人耳目一新、制作精良的影视剧持续推出,留给观众深刻印象的不仅有引人入胜的剧情画面表达,也有细致精美的片头片尾及细节文字的画面包装,如个性的字幕设计或者唯美的片头片尾包装等。本文将介绍如...随着影视制作技术的快速发展,一部部令人耳目一新、制作精良的影视剧持续推出,留给观众深刻印象的不仅有引人入胜的剧情画面表达,也有细致精美的片头片尾及细节文字的画面包装,如个性的字幕设计或者唯美的片头片尾包装等。本文将介绍如何运用After Effects CC 2018的Particular插件制作唯美粒子发散特效,达到提升影视中的图片包装效果。展开更多
The boundary element method for the modal analysis of freevibration for 3-D anisotropic structures using particular solutionshas been developed. The complete polynomials of order two are used toconstruct the particula...The boundary element method for the modal analysis of freevibration for 3-D anisotropic structures using particular solutionshas been developed. The complete polynomials of order two are used toconstruct the particular solutions for general anisotropic materials.The numerical results for 3-D free vibra- tion analysis of anisotropic cantilever beam by the method presented is in goodagreement with the results us- ing the Ritz technique. Foranisotropic materials, the numerical results calculated form theproposed method are in good agreement with the results from MSC.NASTRAN.展开更多
Based on the nonlocal theory and Mindlin plate theory,the governing equations(i.e.,a system of partial differential equations(PDEs)for bending problem)of magnetoelectroelastic(MEE)nanoplates resting on the Pasternak e...Based on the nonlocal theory and Mindlin plate theory,the governing equations(i.e.,a system of partial differential equations(PDEs)for bending problem)of magnetoelectroelastic(MEE)nanoplates resting on the Pasternak elastic foundation are first derived by the variational principle.The polynomial particular solutions corresponding to the established model are then obtained and further employed as basis functions with the method of particular solutions(MPS)to solve the governing equations numerically.It is confirmed that for the present bending model,the new solution strategy possesses more general applicability and superior flexibility in the selection of collocation points.The effects of different boundary conditions,applied loads,and geometrical shapes on the bending properties of MEE nanoplates are evaluated by using the developed method.Some important conclusions are drawn,which should be helpful for the design and applications of electromagnetic nanoplate structures.展开更多
The ever-increasing demand for light weighted hard materials for transportation industries encouraged researchers to develop composites with excellent mechanical properties which can transform it into more economical ...The ever-increasing demand for light weighted hard materials for transportation industries encouraged researchers to develop composites with excellent mechanical properties which can transform it into more economical and eco-friendly.Reinforcing the metals with carbonaceous nanomaterials are progressively in focus due to their excellent capability to inculcate and tailor the properties of MMCs.In the present research,a hybrid nanocomposite of MWCNT-Graphene-AZ31 Mg alloy has been developed by using variable tool rotation speeds with friction stir processing(FSP).Optimized reinforcement ratio of 1.6%vol.MWCNT and 0.3%vol.of graphene have been used with variable tool rotation speeds,whereas other processing parameters are kept constant.The developed specimens were investigated using standard testing equipment for evaluating and comparing the mechanical properties on the basis of the microstructure of the processing regions and their morphological analysis,according to the ASTM standards.The obtained results revealed an improvement of 19.72%in microhardness and 77.5% of compressive strength in comparison with the base metal AZ 31 Magnesium alloy,with a tool rotational speed of 1400rpm.The values of tensile stress and percentage area reduction were recorded as less than that of the base metal matrix,but an increasing trend has been observed in the values of both with the improvement on rotational speeds of the tool.The effectual strengthening mechanisms are analyzed on the bases of SEM images and observed that discussed and found that grain refinement strengthening is the major contributor to the strength of the nanocomposite.展开更多
Aim&Scope:Journal of Mountain Science(JMS)is devoted to mountains and their surrounding lowlands-ecoregions of particular global importance,with a particular emphasis on the important highlands/mountains in the wo...Aim&Scope:Journal of Mountain Science(JMS)is devoted to mountains and their surrounding lowlands-ecoregions of particular global importance,with a particular emphasis on the important highlands/mountains in the world.JMS mainly publishes academic and technical papers concerning environmental changes and sustainable development in mountain areas under natural conditions or/and with the influence of human activities.展开更多
Based on the survey data of public meteorological services,differences between users' needs for public meteorological services were analyzed by using Maslow's hierarchy of needs and the principle of informatio...Based on the survey data of public meteorological services,differences between users' needs for public meteorological services were analyzed by using Maslow's hierarchy of needs and the principle of information availability in behavioral economics. The results show that users' needs for meteorological services follow certain laws,and the public's needs for meteorological information are driven by physiological needs firstly and then by safety needs,while they are driven by upper needs finally. Meanwhile,users' needs for meteorological services have particularity.Under special backgrounds,there are certain differences between users' needs and laws of basic needs,and users' needs are inconsistent with the " ideal needs" of meteorological departments. Studying the laws and particularity of differences between users' needs for meteorological services in detail is conducive to a survey of the public's needs for meteorological services and improvement of meteorological service quality.展开更多
基金Support for this study was provided by grants from the NSFC-Yunnan joint fund to support key projects to G.Chen(U1602264)the National Natural Science Foundation of China(31670322)the Young Academic and Technical Leader Raising Foundation of Yunnan Province(2015HB091)to G.Chen
文摘Flowers or inflorescences often deploy various signals, including visual, olfactory, and gustatory cues,that can be detected by their pollinators. In many plants,these cues and their functions are poorly understood.Deciphering the interactions between floral cues and pollinators is crucial for analyzing the reproductive success of flowering plants. In this study, we examined the composition of the fetid floral scents produced by several Stemona species, including nine S. tuberosa populations from across China, using dynamic headspace adsorption, gas chromatography, and mass spectrometry techniques. We compared variations in floral phenotype,including floral longevity, nectar rewards, pollinator behavior, and flower length and color among the Stemona species. Of the 54 scent compounds identified,the major compounds include fetid dimethyl disulfide,dimethyl trisulfide, 1-pyrroline, butyric acid, p-cresol,isoamyl alcohol, and indole. We detected striking differentiation in floral scent at both the species and population level, and even within a population of plants with different colored flowers. Floral characteristics related to sapromyophily and deceptive pollination,including flower color mimicking livor mortis and a lack of nectar, were found in five Stemona species, indicating that Stemona is a typical sapromyophilous taxon. Species of this monocot genus might employ evolutionary tactics to exploit saprophilous flies for pollination.
文摘The international journal Sciences in Cold and Arid Regions,is devoted to publishing the latest research achievements in processes and the patterns of the Earth surface system in cold and arid regions.Research in cold regions emphasize particularly on the cold-region-characterized physical,chemical and biological processes and their interactions,and on the response of cryosphere to global change and human activities as well as their effects on environment and the acclimatizable strategies.
文摘Adobe After Effects因其可以高效且精确地创建无数种引人注目的动态图形和震撼人心的视觉效果在影视后期合成处理中有着普遍的应用。而在通过After Effects进行创作的过程中,各种插件又让人们如虎添翼。在这里,笔者总结了一个利用AE第三方插件——Trapcode Particular来制作一个看上去具有一种"往事随风"意味的特效制作方法。
基金Under the auspices of National Key R&D Program of China(No.2017YFC0212303,2017YFC0212304)Key Research Program of Frontier Sciences,Chinese Academy of Sciences(No.QYZDB-SSW-DQC045)+1 种基金National Natural Science Foundation of China(No.41775116)Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2017275).
文摘The burning of crop residues emits large quantities of atmospheric aerosols.Published studies have developed inventories of emissions from crop residue burning based on statistical data.In contrast,this study used satellite-retrieved land-cover data(1 km×1 km)as activity data to compile an inventory of atmospheric pollutants emitted from the burning of crop residues in China in 2015.The emissions of PM10,PM2.5,VOCs,NOx,SO2,CO,and NH3 from burning crop straw on nonirrigated farmland in China in 2015 were 610.5,598.4,584.4,230.6,35.4,3329.3,and 36.1 Gg(1 Gg=109 g),respectively;the corresponding emissions from burning paddy rice residues were 234.1,229.7,342.3,57.5,57.5,1122.1,and 21.5 Gg,respectively.The emissions from crop residue burning showed large spatial and temporal variations.The emissions of particulate matter and gaseous pollutants from crop residue burning in nonirrigated farmland were highest in east China,particularly in Shandong,Henan,Anhui,and Sichuan provinces.Emissions from burning paddy rice residue were highest in east and central China,with particularly high levels in Shandong,Jiangsu,Zhejiang,and Hunan provinces.The monthly variations in atmospheric pollutant emissions were similar among different regions,with the highest levels observed in October in north,northeast,northwest,east,and southwest China and in June and July in central and south China.The developed inventory of emissions from crop residue burning is expected to help improve air quality models by providing high-resolution spatial and temporal data.
文摘随着影视制作技术的快速发展,一部部令人耳目一新、制作精良的影视剧持续推出,留给观众深刻印象的不仅有引人入胜的剧情画面表达,也有细致精美的片头片尾及细节文字的画面包装,如个性的字幕设计或者唯美的片头片尾包装等。本文将介绍如何运用After Effects CC 2018的Particular插件制作唯美粒子发散特效,达到提升影视中的图片包装效果。
基金the National Natural Science Foundation of China (No.19872011)
文摘The boundary element method for the modal analysis of freevibration for 3-D anisotropic structures using particular solutionshas been developed. The complete polynomials of order two are used toconstruct the particular solutions for general anisotropic materials.The numerical results for 3-D free vibra- tion analysis of anisotropic cantilever beam by the method presented is in goodagreement with the results us- ing the Ritz technique. Foranisotropic materials, the numerical results calculated form theproposed method are in good agreement with the results from MSC.NASTRAN.
基金Project supported by the National Natural Science Foundation of China(Nos.11872257 and 11572358)the German Research Foundation(No.ZH 15/14-1)。
文摘Based on the nonlocal theory and Mindlin plate theory,the governing equations(i.e.,a system of partial differential equations(PDEs)for bending problem)of magnetoelectroelastic(MEE)nanoplates resting on the Pasternak elastic foundation are first derived by the variational principle.The polynomial particular solutions corresponding to the established model are then obtained and further employed as basis functions with the method of particular solutions(MPS)to solve the governing equations numerically.It is confirmed that for the present bending model,the new solution strategy possesses more general applicability and superior flexibility in the selection of collocation points.The effects of different boundary conditions,applied loads,and geometrical shapes on the bending properties of MEE nanoplates are evaluated by using the developed method.Some important conclusions are drawn,which should be helpful for the design and applications of electromagnetic nanoplate structures.
文摘The ever-increasing demand for light weighted hard materials for transportation industries encouraged researchers to develop composites with excellent mechanical properties which can transform it into more economical and eco-friendly.Reinforcing the metals with carbonaceous nanomaterials are progressively in focus due to their excellent capability to inculcate and tailor the properties of MMCs.In the present research,a hybrid nanocomposite of MWCNT-Graphene-AZ31 Mg alloy has been developed by using variable tool rotation speeds with friction stir processing(FSP).Optimized reinforcement ratio of 1.6%vol.MWCNT and 0.3%vol.of graphene have been used with variable tool rotation speeds,whereas other processing parameters are kept constant.The developed specimens were investigated using standard testing equipment for evaluating and comparing the mechanical properties on the basis of the microstructure of the processing regions and their morphological analysis,according to the ASTM standards.The obtained results revealed an improvement of 19.72%in microhardness and 77.5% of compressive strength in comparison with the base metal AZ 31 Magnesium alloy,with a tool rotational speed of 1400rpm.The values of tensile stress and percentage area reduction were recorded as less than that of the base metal matrix,but an increasing trend has been observed in the values of both with the improvement on rotational speeds of the tool.The effectual strengthening mechanisms are analyzed on the bases of SEM images and observed that discussed and found that grain refinement strengthening is the major contributor to the strength of the nanocomposite.
文摘Aim&Scope:Journal of Mountain Science(JMS)is devoted to mountains and their surrounding lowlands-ecoregions of particular global importance,with a particular emphasis on the important highlands/mountains in the world.JMS mainly publishes academic and technical papers concerning environmental changes and sustainable development in mountain areas under natural conditions or/and with the influence of human activities.
基金Supported by the Meteorological Science and Technology Program of Zhejiang Meteorological Bureau(2015YB04)
文摘Based on the survey data of public meteorological services,differences between users' needs for public meteorological services were analyzed by using Maslow's hierarchy of needs and the principle of information availability in behavioral economics. The results show that users' needs for meteorological services follow certain laws,and the public's needs for meteorological information are driven by physiological needs firstly and then by safety needs,while they are driven by upper needs finally. Meanwhile,users' needs for meteorological services have particularity.Under special backgrounds,there are certain differences between users' needs and laws of basic needs,and users' needs are inconsistent with the " ideal needs" of meteorological departments. Studying the laws and particularity of differences between users' needs for meteorological services in detail is conducive to a survey of the public's needs for meteorological services and improvement of meteorological service quality.