期刊文献+
共找到561篇文章
< 1 2 29 >
每页显示 20 50 100
Modeling Study of Aerosol Indirect Effectson Global Climate with an AGCM 被引量:4
1
作者 王志立 张华 +2 位作者 沈学顺 龚山陵 张小曳 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2010年第5期1064-1077,共14页
Aerosol indirect effects (AIEs) on global climate were quantitatively investigated by introducing aerosol–cloud interaction parameterizations for water stratus clouds into an AGCM (BCC AGCM2.0.1), which was devel... Aerosol indirect effects (AIEs) on global climate were quantitatively investigated by introducing aerosol–cloud interaction parameterizations for water stratus clouds into an AGCM (BCC AGCM2.0.1), which was developed by the National Climate Center of the China Meteorological Administration. The study yielded a global annual mean of -1.14 W m^-2 for the first indirect radiative forcing (IRF), with an obvious seasonal change. In summer, large forcing mainly occurred in mid to high latitudes of the Northern Hemisphere, whereas in winter, large values were found at 60°S. The second indirect effect led to global annual mean changes in net shortwave flux of -1.03 W m^-2 at the top of the atmosphere (TOA), which was relatively significant in mid-latitude regions of both hemispheres. The total AIE reduced the global annual means of net shortwave flux at the TOA and of surface temperature by 1.93 W m^-2 and 0.12 K, respectively. Change in surface temperature induced by the total AIE was clearly larger in the Northern Hemisphere (-0.23 K) than in the Southern Hemisphere, where changes were negligible. The interhemispheric asymmetry in surface cooling resulted in significant differences in changes of the interhemispheric annual mean precipitation rate, which could lead to a tendency for the ITCZ to broaden. The total AIE decreased the global annual mean precipitation rate by 0.055 mm df^-1. 展开更多
关键词 AEROSOL CLOUD RADIATION indirect effect
下载PDF
Indirect Radiative and Climatic Effects of Sulfate and Organic Carbon Aerosols over East Asia Investigated by RIEMS 被引量:3
2
作者 WU Peng-Ping HAN Zhi-Wei 《Atmospheric and Oceanic Science Letters》 2011年第1期7-11,共5页
The indirect radiative and climatic effects of sulfate and organic carbon aerosols over East Asia were investigated using a Regional Integrated Environment Model System (RIEMS) with an empirical aerosol-cloud paramete... The indirect radiative and climatic effects of sulfate and organic carbon aerosols over East Asia were investigated using a Regional Integrated Environment Model System (RIEMS) with an empirical aerosol-cloud parameterization.The first indirect radiative forcing was negative and ranged from-9-0 W m-2 in the domain.The maximum cooling,up to-9 W m-2,occurred in the Chongqing District in winter,whereas the cooling areas were larger during summer than in winter.Organic carbon (OC) aerosols were more abundant in winter than in summer,whereas the sulfate concentration during summer was much higher than during winter.The concentrations of sulfate and OC were comparable in winter,and sulfate played a dominant role in determining indirect radiative forcing in summer,whereas in winter,both sulfate and OC were important.The regional mean indirect radiative forcings were-0.73 W m-2 and-0.41 W m-2 in summer and winter,respectively.The surface cooling caused by indirect effects was more obvious in winter than that in summer.The ground temperature decreased by ~1.2 K in most areas of eastern China in winter,whereas in summer,the temperature decreased (~-1.5 K) in some regions,such as the Yangtze River region,but increased (~0.9 K) in the areas between the Yellow and Yangtze Rivers.In winter,the precipitation decreased by 0-6 mm in most areas of eastern China,but in summer,alternating bands of increasing (up to 80 mm) and decreasing (~-80 mm) precipitation appeared in eastern China. 展开更多
关键词 indirect radiative forcing climatic effect SULFATE organic carbon RIEMS
下载PDF
Aerosol Indirect Effects on Warm Clouds in the Grid-Point Atmospheric Model of IAP LASG(GAMIL) 被引量:7
3
作者 Shi Xiang-Jun Wang Bin +3 位作者 Liu Xiao-Hong Wang Ming-Huai Li Li-Juan Dong Li 《Atmospheric and Oceanic Science Letters》 2010年第4期237-241,共5页
Aerosol indirect effects on warm clouds are estimated in the Grid-point Atmospheric Model of the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics,Institute of Atmosphe... Aerosol indirect effects on warm clouds are estimated in the Grid-point Atmospheric Model of the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics,Institute of Atmospheric Physics(IAP LASG)(GAMIL) with a new two-moment cloud microphysics scheme using two different physically-based aerosol activation parameterizations:Abdul-Razzak and Ghan,and Nenes and Seinfeld.The annual global mean changes in shortwave cloud forcing from preindustrial times to present day(a measure of the aerosol indirect effects) estimated from these two parameterizations are remarkably similar:0.76 W m?2 with the Abdul-Razzak and Ghan parameterization,and 0.78 W m?2 with the Nenes and Seinfeld parameterization.Physically-based parameterizations can provide robust representations of aerosol effects on droplet nucleation,meaning that aerosol activation is no longer the most uncertain factor in modeling aerosol indirect effects. 展开更多
关键词 aerosol indirect effect droplet nucleation atmospheric model GAMIL
下载PDF
Behavior of exciton in direct−indirect band gap Al_(x)Ga_(1−x)As crystal lattice quantum wells
4
作者 Yong Sun Wei Zhang +10 位作者 Shuang Han Ran An Xin-Sheng Tang Xin-Lei Yu Xiu-Juan Miao Xin-Jun Ma Xianglian Pei-Fang Li Cui-Lan Zhao Zhao-Hua Ding Jing-Lin Xiao 《Journal of Semiconductors》 EI CAS CSCD 2024年第3期64-70,共7页
Excitons have significant impacts on the properties of semiconductors.They exhibit significantly different properties when a direct semiconductor turns in to an indirect one by doping.Huybrecht variational method is a... Excitons have significant impacts on the properties of semiconductors.They exhibit significantly different properties when a direct semiconductor turns in to an indirect one by doping.Huybrecht variational method is also found to influence the study of exciton ground state energy and ground state binding energy in Al_(x)Ga_(1−x)As semiconductor spherical quantum dots.The Al_(x)Ga_(1−x)As is considered to be a direct semiconductor at AI concentration below 0.45,and an indirect one at the concentration above 0.45.With regards to the former,the ground state binding energy increases and decreases with AI concentration and eigenfrequency,respectively;however,while the ground state energy increases with AI concentration,it is marginally influenced by eigenfrequency.On the other hand,considering the latter,while the ground state binding energy increases with AI concentration,it decreases with eigenfrequency;nevertheless,the ground state energy increases both with AI concentration and eigenfrequency.Hence,for the better practical performance of the semiconductors,the properties of the excitons are suggested to vary by adjusting AI concentration and eigenfrequency. 展开更多
关键词 exciton effects aluminum gallium arsenide crystal direct band gap semiconductor indirect band gap semiconductor
下载PDF
Near-zone Direct and Indirect Topographic Effects Based on the Rectangular Prism and Surface Element
5
作者 Jian MA Ziqing WEI +2 位作者 Zhenghui YANG Xiaogang LIU Jianfeng JI 《Journal of Geodesy and Geoinformation Science》 2019年第3期8-17,共10页
Helmert’s second method of condensation is an effective method for terrain reduction in the geoid and quasi-geoid determinations. Condensing the masses outside the geoid to a surface layer on the geoid produces sever... Helmert’s second method of condensation is an effective method for terrain reduction in the geoid and quasi-geoid determinations. Condensing the masses outside the geoid to a surface layer on the geoid produces several forms of topographic effects: direct effect on gravity, secondary indirect effect on gravity and indirect effects on the (quasi-) geoid, respectively. To strike a balance between computation accuracy and numerical efficiency, the global integration region of topographic effects is usually divided into near zone and far zone. We focus on the computation of near-zone topographic effects, which are functions of actual topographic masses and condensed masses. Since there have already been mature formulas for gravitational attraction and potential of actual topographic masses using rectangular prism model, we put forward surface element model for condensed masses. Afterwards, the formulas for near-zone direct and indirect effects are obtained easily by combining the rectangular prism model and surface element model. To overcome the planar approximation errors involved with the new formulas for near-zone topographic effects, the Earth’s curvature can be taken into account. It is recommended to apply the formulas based on the rectangular prism and surface element considering the Earth’s curvature to calculate near-zone topographic effects for high-accuracy demand to determine geoid and quasi-geoid. 展开更多
关键词 helmert's second method of condensation DIRECT effect indirect effect rectangular PRISM SURFACE ELEMENT
下载PDF
Indirect Radiative Forcing and Climatic Effect of the Anthropogenic Nitrate Aerosol on Regional Climate of China 被引量:13
6
作者 李树 王体健 +1 位作者 庄炳亮 韩永 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2009年第3期543-552,共10页
The regional climate model (RegCM3) and a tropospheric atmosphere chemistry model (TACM) were coupled, thus a regional climate chemistry modeling system (RegCCMS) was constructed, which was applied to investigat... The regional climate model (RegCM3) and a tropospheric atmosphere chemistry model (TACM) were coupled, thus a regional climate chemistry modeling system (RegCCMS) was constructed, which was applied to investigate the spatial distribution of anthropogenic nitrate aerosols, indirect radiative forcing, as well as its climatic effect over China. TACM includes the thermodynamic equilibrium model ISORROPIA and a condensed gas-phase chemistry model. Investigations show that the concentration of nitrate aerosols is relatively high over North and East China with a maximum of 29μg m-3 in January and 8 μg m-3 in July. Due to the influence of air temperature on thermodynamic equilibrium, wet scavenging of precipitation and the monsoon climate, there are obvious seasonal differences in nitrate concentrations. The average indirect radiative forcing at the tropopause due to nitrate aerosols is -1.63 W m 2 in January and -2.65 W m 2 in July, respectively. In some areas, indirect radiative forcing reaches -10 W m-2. Sensitivity tests show that nitrate aerosols make the surface air temperature drop and the precipitation reduce on the national level. The mean changes in surface air temperature and precipitation are 0.13 K and -0.01 mm d-1 in January and -0.09 K and -0.11 mm d-1 in July, respectively, showing significant differences in different regions. 展开更多
关键词 nitrate aerosol indirect radiative forcing indirect climate effect regional climate atmosphericchemistry
下载PDF
Analytical Studies of the Cloud Droplet Spectral Dispersion Influence on the First Indirect Aerosol Effect 被引量:5
7
作者 解小宁 刘晓东 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2013年第5期1313-1319,共7页
Atmospheric aerosols (acting as cloud condensation nuclei) can enhance the cloud droplet number concentration and reduce the cloud droplet size, and in turn affect the cloud optical depth, as well as the cloud albed... Atmospheric aerosols (acting as cloud condensation nuclei) can enhance the cloud droplet number concentration and reduce the cloud droplet size, and in turn affect the cloud optical depth, as well as the cloud albedo, and thereby exert a radiative influence on climate (the first indirect aerosol effect). In this paper, based on various relationships between cloud droplet spectral dispersion (c) and cloud droplet number concentration (Nc), we analytically derive the corresponding expressions of the cloud radiative forcing induced by changes in the cloud droplet number concentration. Further quantitative evaluation indicates that the cloud radiative forcing induced by aerosols for the different ^-Nc relationships varies from -29.1% to 25.2%, compared to the case without considering spectral dispersion (e = 0). Our results suggest that an accurate description of e - Nc relationships helps to reduce the uncertainty of the first indirect aerosol effect and advances our scientific understanding of aerosol-cloud-radiation interactions. 展开更多
关键词 spectral dispersion cloud radiative forcing the first indirect aerosol effect
下载PDF
First Surface-based Estimation of the Aerosol Indirect Effect over a Site in Southeastern China 被引量:2
8
作者 Jianjun LIU Zhanqing LI 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2018年第2期169-181,共13页
The deployment of the U.S. Atmospheric Radiation Measurement mobile facility in Shouxian from May to December 2008 amassed the most comprehensive set of measurements of atmospheric, surface, aerosol, and cloud variabl... The deployment of the U.S. Atmospheric Radiation Measurement mobile facility in Shouxian from May to December 2008 amassed the most comprehensive set of measurements of atmospheric, surface, aerosol, and cloud variables in China. This deployment provided a unique opportunity to investigate the aerosol-cloud interactions, which are most challenging and, to date, have not been examined to any great degree in China. The relationship between cloud droplet effective radius (CER) and aerosol index (AI) is very weak in summer because the cloud droplet growth is least affected by the competition for water vapor. Mean cloud liquid water path (LWP) and cloud optical depth (COD) significantly increase with increasing AI in fall. The sensitivities of CER and LWP to aerosol loading increases are not significantly different under different air mass conditions. There is a significant correlation between the changes in hourly mean AI and the changes in hourly mean CER, LWP, and COD. The aerosol first indirect effect (FIE) is estimated in terms of relative changes in both CER (FIEcER) and COD (FIEcoD) with changes in AI for different seasons and air masses. FIEcoD and FIEcER are similar in magnitude and close to the typical FIE value of - 0.23, and do not change much between summer and fall or between the two different air mass conditions. Similar analyses were done using spaceborne Moderate Resolution Imaging Spectroradiometer data. The satellite-derived FIE is contrary to the FIE estimated from surface retrievals and may have large uncertainties due to some inherent limitations. 展开更多
关键词 ground-based measurements aerosol indirect effect southeastern China
下载PDF
An improved recommendation algorithm via weakening indirect linkage effect 被引量:1
9
作者 陈光 邱天 沈小泉 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第7期606-611,共6页
We propose an indirect-link-weakened mass diffusion method(IMD), by considering the indirect linkage and the source object heterogeneity effect in the mass diffusion(MD) recommendation method. Experimental results... We propose an indirect-link-weakened mass diffusion method(IMD), by considering the indirect linkage and the source object heterogeneity effect in the mass diffusion(MD) recommendation method. Experimental results on the MovieLens, Netflix, and RYM datasets show that, the IMD method greatly improves both the recommendation accuracy and diversity, compared with a heterogeneity-weakened MD method(HMD), which only considers the source object heterogeneity. Moreover, the recommendation accuracy of the cold objects is also better elevated in the IMD than the HMD method. It suggests that eliminating the redundancy induced by the indirect linkages could have a prominent effect on the recommendation efficiency in the MD method. 展开更多
关键词 bipartite network mass diffusion recommender system indirect linkage effect
下载PDF
Modeling of the Second Indirect Effect of Anthropogenic Aerosols in East Asia 被引量:2
10
作者 WU Peng-Ping HAN Zhi-Wei 《Atmospheric and Oceanic Science Letters》 2011年第6期316-323,共8页
This study investigated the second indirect climatic effect of anthropogenic aerosols,including sulfate,organic carbon(OC) ,and black carbon(BC) ,over East Asia.The seasonal variation of the climatic response to the s... This study investigated the second indirect climatic effect of anthropogenic aerosols,including sulfate,organic carbon(OC) ,and black carbon(BC) ,over East Asia.The seasonal variation of the climatic response to the second indirect effect was also characterized.The simulation period for this study was 2006.Due to a decrease in autoconversion rate from cloud water to rain as a result of aerosols,the cloud liquid water path(LWP) ,and radiative flux(RF) at the top of the atmosphere(TOA) changed dramatically,increasing by 14.3 g m-2 and decreasing by-4.1 W m-2 in terms of domain and annual average.Both LWP and RF changed most in autumn. There were strong decreases in ground temperature in Southwest China,the middle reaches of the Yangtze River in spring and autumn,while maximum cooling of up to-1.5 K occurred in the Chongqing district.The regional and annual mean change in ground temperature reached-0.2 K over eastern China.In all seasons except summer,precipitation generally decreased in most areas north of the Yangtze River,whereas precipitation changed little in South China.Precipitation changed most in summer,with alternating bands of increasing(~40 mm) and decreasing(~40 mm) precipitation appearing in eastern China.Precipitation decreased by 1.5-40 mm over large areas of Northeast China and the Huabei Plain.The domain and annual mean change in precipitation was approximately-0.3 mm over eastern China.The maximum reduction in precipitation occurred in summer,with mean absolute and relative changes of-1.2 mm and-3.8%over eastern China.This study revealed considerable climate responses to the second indirect effect of aerosols over specific regions of China. 展开更多
关键词 AEROSOLS second indirect effect autoconversion liquid water path model simulation
下载PDF
Observation on the Therapeutical Effect of Adjuvant Arthritis in Rats with Medicinal Indirect Moxibustion
11
作者 Zhu Baijun Wang Yuanchao +1 位作者 Dai Huiting Xu Qingyan(Institute of Acupuncture and Moxibustion China Academy of TCM, 100700) 《中国针灸》 CAS CSCD 北大核心 1995年第S2期240-241,共2页
ObservationontheTherapeuticalEffectofAdjuvantArthritisinRatswithMedicinalIndirectMoxibustion¥ZhuBaijun;WangY... ObservationontheTherapeuticalEffectofAdjuvantArthritisinRatswithMedicinalIndirectMoxibustion¥ZhuBaijun;WangYuanchao;DaiHuitin... 展开更多
关键词 OBSERVATION ARTHRITIS effect indirect MEDICINAL MOXIBUSTION ADJUVANT RATS Therapeutical in
下载PDF
A Simple Method of Measuring Vaccine Effects on Infectiousness and Contagion
12
作者 Yasutaka Chiba 《Open Journal of Statistics》 2013年第4期7-15,共9页
The vaccination of one person may prevent another from becoming infected, either because the vaccine may prevent the first person from acquiring the infection and thereby reduce the probability of transmission to the ... The vaccination of one person may prevent another from becoming infected, either because the vaccine may prevent the first person from acquiring the infection and thereby reduce the probability of transmission to the second, or because, if the first person is infected, the vaccine may impair the ability of the infectious agent to initiate new infections. The former mechanism is referred as a contagion effect and the latter is referred as an infectiousness effect. By applying a principal stratification approach, the conditional infectiousness effect has been defined, but the contagion effect is not defined using this approach. Recently, new definitions of unconditional infectiousness and contagion effects were provided by applying a mediation analysis approach. In addition, a simple relationship between conditional and unconditional infectiousness effects was found under a number of assumptions. These two infectiousness effects can be assessed by very simple estimation and sensitivity analysis methods under the assumptions. Nevertheless, such simple methods to assess the contagion effect have not been discussed. In this paper, we review the methods of assessing infectiousness effects, and apply them to the inference of the contagion effect. The methods provided here are illustrated with hypothetical vaccine trial data. 展开更多
关键词 indirect effect INTERFERENCE MEDIATION Analysis Potential OUTCOME Principal STRATIFICATION
下载PDF
On the parameters for electrocaloric effect predicted by indirect method
13
作者 刘宏波 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第11期486-488,共3页
The influences of specific heat capacity CP, temperature step ?T, electric field step ?E, and initial electric field E1 on predicted electrocaloric(EC) temperature ?T of monodomain Ba TiO3 are examined by combini... The influences of specific heat capacity CP, temperature step ?T, electric field step ?E, and initial electric field E1 on predicted electrocaloric(EC) temperature ?T of monodomain Ba TiO3 are examined by combining the Maxwell equation and phenomenological theory. Since the procedure is similar to indirect measurement of the EC effect, the results can serve as a reference for experiments. The results suggest that(i) it is reasonable to use zero-field CP,(ii) optimized ?T should be 2 K,(iii) it is better to keep △E 〈 EC, and(iv) E1〈 EC. Here, EC is the coercive field of material. 展开更多
关键词 electrocaloric effect indirect method BaTiO3
下载PDF
雷电间接效应多重脉冲组电流产生装置的设计
14
作者 刘宏伟 栾崇彪 +3 位作者 袁建强 肖金水 黄宇鹏 王凌云 《强激光与粒子束》 CAS CSCD 北大核心 2024年第2期1-7,共7页
针对雷电间接效应多重脉冲组电流模拟需求,完成了雷电间接效应多重脉冲组模拟源的设计,采用20个Crowbar电路支路,通过分时放电的方式实现1个脉冲串内多脉冲输出需求,每个支路可以实现最小间隔30 ms的重复频率放电,从而实现3个脉冲串的... 针对雷电间接效应多重脉冲组电流模拟需求,完成了雷电间接效应多重脉冲组模拟源的设计,采用20个Crowbar电路支路,通过分时放电的方式实现1个脉冲串内多脉冲输出需求,每个支路可以实现最小间隔30 ms的重复频率放电,从而实现3个脉冲串的输出需求。对放电支路的参数进行了详细设计,分析了电容、波尾电路电感、波尾电路电阻参数变化对输出特性的影响。分析了采用并联大电容实现放电电容重复频率快速充电的可行性,完成了装置的初步结构设计并结合装置结构简要分析了电路模拟参数设置的合理性。该装置建成后,可为电子、电气设备等开展测试提供技术支持。 展开更多
关键词 雷电间接效应 多重脉冲组(H波) 雷电模拟源 冲击电流发生器
下载PDF
碳排放权交易对试点地区绿色发展的影响及溢出效应——基于PSM-DID和SDID模型的实证分析
15
作者 余谦 吴婷 +1 位作者 覃一冬 贾鹏 《工业技术经济》 北大核心 2024年第3期104-114,共11页
在碳中和、碳达峰背景下,本文选用2003~2021年全国273个地级市的面板数据,以碳排放权交易试点(CETP)为出发点,用生态效率测度绿色发展水平,通过PSM-DID和SDID模型实证检验了CETP对绿色发展的直接效应、间接效应和空间溢出效应。研究发现... 在碳中和、碳达峰背景下,本文选用2003~2021年全国273个地级市的面板数据,以碳排放权交易试点(CETP)为出发点,用生态效率测度绿色发展水平,通过PSM-DID和SDID模型实证检验了CETP对绿色发展的直接效应、间接效应和空间溢出效应。研究发现:(1)CETP能显著促进绿色发展,且通过了安慰剂检验和稳健性检验;(2)CETP产生的创新效应对绿色发展有推动作用,但产业结构效应不显著;(3)CETP对周边试点城市产生了显著负向的溢出效应,但对非试点城市的生态效率无明显影响。最后,结合以上研究结论,提出了政策建议。 展开更多
关键词 碳排放权交易试点 绿色发展水平 生态效率 间接效应 空间溢出效应 碳配额
下载PDF
活髓切断术与间接盖髓术对乳磨牙深龋患儿治疗效果及预后的影响比较
16
作者 孙晖 马腾飞 韩良 《中国美容医学》 CAS 2024年第9期152-155,共4页
目的:对比分析活髓切断术与间接盖髓术对乳磨牙深龋患儿治疗效果及预后的影响。方法:对2019年1月-2023年2月笔者医院收治的152例乳磨牙深龋患儿的临床资料进行回顾性分析,按治疗方法的不同分为A组(n=78,96颗患牙)和B组(n=74,96颗患牙),... 目的:对比分析活髓切断术与间接盖髓术对乳磨牙深龋患儿治疗效果及预后的影响。方法:对2019年1月-2023年2月笔者医院收治的152例乳磨牙深龋患儿的临床资料进行回顾性分析,按治疗方法的不同分为A组(n=78,96颗患牙)和B组(n=74,96颗患牙),A组予以活髓切断术治疗,B组予以间接盖髓术治疗,治疗后均随访12个月。比较两组治疗效果、牙本质桥形成率、牙齿咀嚼功能、并发症发生情况和学龄前儿童口腔健康影响量表(ECOHIS)的差异。结果:治疗后12个月,A组患牙的修复成功率高于B组(P<0.05);治疗后6、12个月,A组患牙的牙本质桥形成率均高于B组(P<0.05);治疗后12个月,两组牙齿咀嚼功能各维度评分均高于同组治疗前,且A组均高于B组(P<0.05);A组的并发症发生率低于B组(P<0.05);两组ECOHIS量表口腔症状、口腔功能、心理状态、社会交往评分均低于同组治疗前,且A组低于B组(P<0.05)。结论:活髓切断术相较间接盖髓术对乳磨牙深龋患儿的疗效更加显著,能有效提高修复成功率,促进牙本质桥形成,改善牙齿咀嚼功能,提高生存质量,减少并发症的发生。 展开更多
关键词 乳磨牙深龋 活髓切断术 间接盖髓术 治疗效果 预后
下载PDF
政府R&D补贴的技术创新效应分析--基于2009-2021年中国的经验数据
17
作者 臧传琴 《山东商业职业技术学院学报》 2024年第4期1-8,共8页
政府R&D补贴既可以通过提供公共服务的方式直接作用于技术创新,也可以通过对社会资本的引导作用间接影响技术创新,其总效应取决于两种影响的方向与大小。基于2009—2021年中国的经验数据,建立了由技术创新方程和引致方程共同组成的... 政府R&D补贴既可以通过提供公共服务的方式直接作用于技术创新,也可以通过对社会资本的引导作用间接影响技术创新,其总效应取决于两种影响的方向与大小。基于2009—2021年中国的经验数据,建立了由技术创新方程和引致方程共同组成的动态模型,对政府R&D补贴的技术创新效应进行了实证分析。结果发现:持续增加的政府R&D补贴带来了国内专利授权数量的稳定增加,技术创新效应较为显著;政府R&D补贴不仅对技术创新产生了积极的直接影响,也通过引导社会资本投资于研发领域而对技术创新产生了积极的间接影响;政府R&D补贴的技术创新效应存在区域差异,中东部地区为正,而西部地区为负。提高资金使用效率、积极引导社会资本投资技术研发、努力改善欠发达地区的研发环境,无疑是提高政府R&D补贴技术创新效应的必要选择。 展开更多
关键词 R&D补贴 技术创新 直接效应 间接效应
下载PDF
飞机及分系统雷电效应标准及测试浅析
18
作者 陈功 蒋东 +2 位作者 王奇福 曾世超 王风 《强激光与粒子束》 CAS CSCD 北大核心 2024年第4期107-112,共6页
对国内外关军用及民用飞机平台、分系统及设备雷电标准进行分析,针对雷电直接效应和雷电间接效应的所有测试项目,详述每个测试项目的适用区域、波形要求、测试配置等。结合现有国内雷电设计验证标准及测试存在的不足,提出提升测试设备... 对国内外关军用及民用飞机平台、分系统及设备雷电标准进行分析,针对雷电直接效应和雷电间接效应的所有测试项目,详述每个测试项目的适用区域、波形要求、测试配置等。结合现有国内雷电设计验证标准及测试存在的不足,提出提升测试设备与试验验证技术匹配性、扩展军用标准测试领域、统一同军种同一平台要求等建议。通过对军用机载平台、设备及分系统关于雷电设计验证标准及测试的分析,为相关产品设计师及试验人员提供设计指标参考,明确产品关于雷电防护的设计要求及验证要求,做到有的放矢,提高设计费效比。 展开更多
关键词 雷电直接效应 雷电间接效应 初始先导附着 扫掠通道附着 电弧引入
下载PDF
绿色金融、碳交易与产业绩效:影响机理及中国7个试点的力证 被引量:1
19
作者 刘平阔 慕雨坪 《中国软科学》 CSCD 北大核心 2024年第4期25-36,共12页
目前,各界对绿色金融和碳交易影响产业绩效的认知和预期仍相对模糊或片面。基于实际发展进程与客观诉求,对C-D生产函数进行重构与改进,通过实证分析验证绿色金融和碳交易影响产业绩效的动态机制。结果表明:直接影响,绿色金融和碳交易的... 目前,各界对绿色金融和碳交易影响产业绩效的认知和预期仍相对模糊或片面。基于实际发展进程与客观诉求,对C-D生产函数进行重构与改进,通过实证分析验证绿色金融和碳交易影响产业绩效的动态机制。结果表明:直接影响,绿色金融和碳交易的导入会短暂阻碍产业绩效的提升,但跨越“拐点”后可显著促进产业发展;间接影响,绿色金融和碳交易的推进均存在一个最佳时间段,不仅可通过生产要素影响产业绩效,而且可促进“劳动密集型”向“资本密集型+能源密集型”的结构升级;现阶段绿色金融和碳交易的相互影响不具有对称性。只有对“试点建设”成功经验和作用规律进行科学总结才可为“全国推广”奠定坚实基础。 展开更多
关键词 改进生产函数 非线性关系 直接影响与间接影响 中介效应 调节效应
下载PDF
上海市洪涝灾害损失对长江下游地区的辐射影响
20
作者 苏鑫 胡庆芳 +3 位作者 郭靖 王银堂 李伶杰 王磊之 《中国防汛抗旱》 2024年第3期27-31,69,共6页
随着区域经济一体化程度的加深,跨区域产业关联损失已成为灾害损失评估不容忽视的一部分,准确量化洪涝灾害损失的辐射影响对于制定防灾减灾措施、减少洪涝灾害损失具有重要作用。在系统评估了不同暴雨重现期情景下上海市减停产损失的基... 随着区域经济一体化程度的加深,跨区域产业关联损失已成为灾害损失评估不容忽视的一部分,准确量化洪涝灾害损失的辐射影响对于制定防灾减灾措施、减少洪涝灾害损失具有重要作用。在系统评估了不同暴雨重现期情景下上海市减停产损失的基础上,采用两区域投入产出模型,测算和分析了长江下游地区不同省(直辖市)的区域内乘数效应、区域间溢出效应和区域间反馈效应,量化了上海市洪涝灾害损失对长江下游地区的辐射影响。结果表明,暴雨重现期10 a、20 a、30 a、50 a、100 a时,上海市的减停产损失分别为14.01亿元、19.83亿元、25.58亿元、33.82亿元和46.24亿元;在长江下游地区,上海市与浙江省的经济相互影响强度最大,且跨区域产业关联损失以溢出效应为主导;上海市发生洪涝灾害时,跨区域波及效应将导致长江下游地区损失增加26.24%。因此,在城市之间联系日益紧密的情况下,不仅要关注洪涝灾害对自身的影响,同时也要采取有效措施减少地域之间的波及影响,以便更有效地开展防灾减灾工作。 展开更多
关键词 洪涝灾害 间接损失评估 跨区域辐射影响 上海市 长江下游地区
下载PDF
上一页 1 2 29 下一页 到第
使用帮助 返回顶部