期刊文献+
共找到41篇文章
< 1 2 3 >
每页显示 20 50 100
Seismic hazard assessment of Tehran,Iran with emphasis on near-fault rupture directivity effects
1
作者 Ehsan Bazarchi Reza Saberi Majid Alinejad 《Earthquake Science》 CSCD 2018年第1期1-11,共11页
Many destructive earthquakes happened in Tehran, Iran in the last centuries. The existence of active faults like the North Tehran is the main cause of seismicity in this city. According to past investigations, it is e... Many destructive earthquakes happened in Tehran, Iran in the last centuries. The existence of active faults like the North Tehran is the main cause of seismicity in this city. According to past investigations, it is estimated that in the scenario of activation of the North Tehran fault, many structures in Tehran will collapse. Therefore, it is necessary to incorporate the near field rupture directivity effects of this fault into the seismic hazard assessment of important sites in Tehran. In this study, using calculations coded in MATLAB, Probabilistic Seismic Hazard Analysis (PSHA) is conducted for an important site in Tehran. Following that, deaggregation technique is performed on PSHA and the contribution of seis- mic scenarios to hazard is obtained in the range of distance and magnitude. After identifying the North Tehran fault as the most hazardous source affecting the site in 10000-year return period, rupture directivity effects of this fault is incorporated into the seismic hazard assessment using Somerville et al. (1997) model with broadband approach and Shahi and Baker (2011) model with narrowband approach. The results show that the narrowband approach caused a 27% increase in the peak of response spectrum in 10000-year return period compared with the conventional PSHA. Therefore, it is necessary to incorporate the near fault rupture directivity effects into the higher levels of seismic hazard assessment attributed to important sites. 展开更多
关键词 Probabilistic seismic hazard analysis North Tehran fault rupture directivity effect DEAGGREGATION controlling earthquake
下载PDF
Topographic effects observed at Amatrice hill during the 2016-2017 Central Italy seismic sequence 被引量:2
2
作者 Gerardo Grelle Laura Bonito +4 位作者 Maresca Rosalba Silvia Iacurto Claudia Madiai Paola Revellino Giuseppe Sappa 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2021年第1期63-78,共16页
The estimate of seismic site effects by experimental approaches is based on different assumptions aimed at simplifying the complex actual site conditions and related uncertainties.However,the reliability of the result... The estimate of seismic site effects by experimental approaches is based on different assumptions aimed at simplifying the complex actual site conditions and related uncertainties.However,the reliability of the results can increase if the experimental data is focused on quite strong seismic sequences and the on-site acquisition of a large number of signals is deemed strategic for the assessment of the expected phenomena.Based on these considerations,the ground motion at the Red Zone sector of Amatrice hill,violently struck by the 2016-2017 Central Italy seismic sequence,was analyzed via an observational approach.A large set of weak motions(moment magnitude Mw 2.5-3.9)was analyzed in this study by means of standard(SSR)and horizontal to vertical(HVSR)spectral ratio techniques.The results from the experimental analysis of the site effects by using weak motion and noise signals show a significant amplification at the top of Amatrice hill with a remarkable polarization of the motion and changes in spectral shapes according to the topographic setting of the relief. 展开更多
关键词 topographic effects standard spectra ratio(SSR) horizontal and vertical spectral ratio(HVSR) directional effects
下载PDF
Simulating Aerosol Optical Depth and Direct Radiative Effects over the Tibetan Plateau with a High-Resolution CAS FGOALS-f3 Model
3
作者 Min ZHAO Tie DAI +4 位作者 Hao WANG Qing BAO Yimin LIU Hua ZHANG Guangyu SHI 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2022年第12期2137-2155,I0020-I0022,共22页
Current global climate models cannot resolve the complex topography over the Tibetan Plateau(TP)due to their coarse resolution.This study investigates the impacts of horizontal resolution on simulating aerosol and its... Current global climate models cannot resolve the complex topography over the Tibetan Plateau(TP)due to their coarse resolution.This study investigates the impacts of horizontal resolution on simulating aerosol and its direct radiative effect(DRE)over the TP by applying two horizontal resolutions of about 100 km and 25 km to the Chinese Academy of Sciences Flexible Global Ocean-Atmosphere Land System(CAS FGOALS-f3)over a 10-year period.Compared to the AErosol RObotic NETwork observations,a high-resolution model(HRM)can better reproduce the spatial distribution and seasonal cycles of aerosol optical depth(AOD)compared to a low-resolution model(LRM).The HRM bias and RMSE of AOD decreased by 0.08 and 0.12,and the correlation coefficient increased by 0.22 compared to the LRM.An LRM is not sufficient to reproduce the aerosol variations associated with fine-scale topographic forcing,such as in the eastern marginal region of the TP.The difference between hydrophilic aerosols in an HRM and LRM is caused by the divergence of the simulated relative humidity(RH).More reasonable distributions and variations of RH are conducive to simulating hydrophilic aerosols.An increase of the 10-m wind speed in winter by an HRM leads to increased dust emissions.The simulated aerosol DREs at the top of the atmosphere(TOA)and at the surface by the HRM are–0.76 W m^(–2)and–8.72 W m^(–2)over the TP,respectively.Both resolution models can capture the key feature that dust TOA DRE transitions from positive in spring to negative in the other seasons. 展开更多
关键词 Tibetan Plateau high-resolution climate model aerosol optical depth aerosol direct radiative effect
下载PDF
Effects of Tensor Couplings on Nucleonic Direct URCA Processes in Neutron Star Matter
4
作者 许妍 黄修林 +2 位作者 刘承志 特木尔巴根 刘广洲 《Chinese Physics Letters》 SCIE CAS CSCD 2016年第9期132-135,共4页
The relativistic neutrino emissivity of the nucleonic direct URCA processes in neutron star matter is investigated within the relativistic Hartree-Fock approximation. We particularly study the influences of the tensor... The relativistic neutrino emissivity of the nucleonic direct URCA processes in neutron star matter is investigated within the relativistic Hartree-Fock approximation. We particularly study the influences of the tensor couplings of vector mesons ω and ρ on the nucleonic direct URCA processes. It is found that the inclusion of the tensor couplings of vector mesons w and p can slightly increase the maximum mass of neutron stars. In addition, the results indicate that the tensor couplings of vector mesons ω and ρ lead to obvious enhancement of the total neutrino emissivity for the nucleonic direct URCA processes, which must accelerate the cooling rate of the non- superfluid neutron star matter. However, when considering only the tensor coupling of vector meson ρ, the neutrino emissivity for the nucleonic direct URCA processes slightly declines at low densities and significantly increases at high densities. That is, the tensor coupling of vector meson ρ leads to the slow cooling rate of a low-mass neutron star and rapid cooling rate of a massive neutron star. 展开更多
关键词 of is it for effects of Tensor Couplings on Nucleonic Direct URCA Processes in Neutron Star Matter in on
下载PDF
Effect of Curcumin on Influenza Virus HIN1 and H3N2 in Vitro 被引量:15
5
作者 刘妮 孟以蓉 +2 位作者 张俊丽 朱宇同 黄正昌 《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》 SCIE CAS CSCD 2008年第9期534-535,共2页
Objective:To investigate the inhibitory effect of curcumin on influenza virus HIN1 and H3N2 in vitro, Methods:The directly killing role of cureumin extract in vitro to influenza virus type A subtype H1N1 and H3N2 wa... Objective:To investigate the inhibitory effect of curcumin on influenza virus HIN1 and H3N2 in vitro, Methods:The directly killing role of cureumin extract in vitro to influenza virus type A subtype H1N1 and H3N2 was evaluated by the canine kidney cells (MDCK), Results:The largest non toxic concentration of curcumin extract was 12, 5g/L and the effective inhibitory concentration to H1N1 and H3N2 was 6, 25G/1 AND 1,56g/L respectively, Conclusion: Curcumin extract have directly killing effect on H1N1 and H3N2 infections. 展开更多
关键词 CURCUMIN influenza virus directly killing effect
下载PDF
Spatial Distribution of Large-scale Landslides Induced by the 5.12 Wenchuan Earthquake 被引量:23
6
作者 XU Qiang ZHANG Shuai LI Weile 《Journal of Mountain Science》 SCIE CSCD 2011年第2期246-260,共15页
The 5.12 Wenchuan Earthquake in 2008 induced hundreds of large-scale landslides. This paper systematically analyzes 112 large-scale landslides (surface area > 50000 m2), which were identified by interpretation of r... The 5.12 Wenchuan Earthquake in 2008 induced hundreds of large-scale landslides. This paper systematically analyzes 112 large-scale landslides (surface area > 50000 m2), which were identified by interpretation of remote sensing imagery and field investigations. The analysis suggests that the distribution of large-scale landslides is affected by the following four factors: (a) distance effect: 80% of studied large-scale landslides are located within a distance of 5 km from the seismic faults. The farther the distance to the faults, the lower the number of large-scale landslides; (b) locked segment effect: the large-scale landslides are mainly located in five concentration zones closely related with the crossing, staggering and transfer sections between one seismic fault section and the next one, as well as the end of the NE fault section. The zone with the highest concentration was the Hongbai-Chaping segment, where a great number of large-scale landslides including the two largest landslides were located. The second highest concentration of large-scale landslides was observed in the Nanba-Donghekou segment at the end of NE fault, where the Donghekou landslide and the Woqian landslide occurred; (c) Hanging wall effect: about 70% of the large-scale landslides occurred on the hanging wall of the seismic faults; and (d) direction effect: in valleys perpendicular to the seismic faults, the density of large-scale landslides on the slopes facing the seismic wave is obviously higher than that on the slopes dipping in the same direction as the direction of propagation of the seismic wave. Meanwhile, it is found that the sliding and moving directions of large-scale landslides are related to the staggering direction of the faults in each section. In Qingchuan County where the main fault activity was horizontal twisting and staggering, a considerable number of landslides showed the feature of sliding and moving in NE direction which coincides with the staggering direction of the seismic faults. 展开更多
关键词 5.12 Wenchuan Earthquake LANDSLIDES Distribution pattern Direction effect Locked segment effect
下载PDF
Climate Responses to Direct Radiative Forcing of Anthropogenic Aerosols,Tropospheric Ozone,and Long-Lived Greenhouse Gases in Eastern China over 1951–2000 被引量:24
7
作者 常文渊 廖宏 王会军 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2009年第4期748-762,共15页
A unified chemistry-aerosol-climate model is applied in this work to compare climate responses to changing concentrations of long-lived greenhouse gases (GHGs, CO2, CH4, N2O), tropospheric O3, and aerosols during th... A unified chemistry-aerosol-climate model is applied in this work to compare climate responses to changing concentrations of long-lived greenhouse gases (GHGs, CO2, CH4, N2O), tropospheric O3, and aerosols during the years 1951-2000. Concentrations of sulfate, nitrate, primary organic carbon (POA), secondary organic carbon (SOA), black carbon (BC) aerosols, and tropospheric 03 for the years 1950 and 2000 are obtained a priori by coupled chemistry-aerosol-GCM simulations, and then monthly concentrations are interpolated linearly between 1951 and 2000. The annual concentrations of GHGs are taken from the IPCC Third Assessment Report. BC aerosol is internally mixed with other aerosols. Model results indicate that the sinmlated climate change over 1951-2000 is sensitive to anthropogenic changes in atmospheric components. The predicted year 2000 global mean surface air temperature can differ by 0.8℃ with different forcings. Relative to the climate simulation without changes in GHGs, O3, and aerosols, anthropogenic forcings of SO4^2-, BC, BC+SO4^2-, BC+SO4^2- +POA, BC+SO4^2- +POA+SOA+NO3^-, O3, and GHGs are predicted to change the surface air temperature averaged over 1971-2000 in eastern China, respectively, by -0.40℃, +0.62℃, +0.18℃, +0.15℃, -0.78℃, +0.43℃, and +0.85℃, and to change the precipitation, respectively, by -0.21, +0.07, -0.03, +0.02, -0.24, -0.08, and +0.10 mm d^-1. The authors conclude that all major aerosols are as important as GHGs in influencing climate change in eastern China, and tropospheric O3 also needs to be included in studies of regional climate change in China. 展开更多
关键词 direct effect of aerosol tropospheric ozone greenhouse gases transient simulation
下载PDF
Direct Climatic Effect of Aerosols and Interdecadal Variations over East Asia Investigated by a Regional Coupled Climate-Chemistry/Aerosol Model 被引量:5
8
作者 HAN Zhi-Wei XIONG Zhe LI Jia-Wei 《Atmospheric and Oceanic Science Letters》 2011年第6期299-303,共5页
The direct climatic effect of aerosols for the 1980-2000 period over East Asia was numerically investigated by a regional scale coupled climate-chemistry/ aerosol model, which includes major anthropogenic aerosols (s... The direct climatic effect of aerosols for the 1980-2000 period over East Asia was numerically investigated by a regional scale coupled climate-chemistry/ aerosol model, which includes major anthropogenic aerosols (sulfate, black carbon, and organic carbon) and natural aerosols (soil dust and sea salt). Anthropogenic emissions used in model simulation are from a global emission inventory prepared for the Intergovernmental Panel on Climate Change Fifth Assessment Report (IPCC AR5), whereas natural aerosols are calculated online in the model. The simulated 20-year average direct solar radiative effect due to aerosols at the surface was estimated to be in a range of-9- -33 W m-2 over most areas of China, with maxima over the Gobi desert of West China, and-12 W m-2 to -24 W m-2 over the Sichuan Basin, the middle and lower reaches of the Yellow River and the Yangtze River. Aerosols caused surface cooling in most areas of East Asia, with maxima of-0.8℃ to -1.6℃ over the deserts of West China, the Sichuan Basin, portions of central China, and the middle reaches of the Yangtze River. Aerosols induced a precipitation decrease over almost the entire East China, with maxima of-90 mm/year to -150 mm/year over the Sichuan Basin, the middle reaches of the Yangtze River and the lower reaches of the Yellow River. Interdecadal variation of the climate response to the aerosol direct radiative effect is evident, indicating larger decrease in surface air temperature and stronger per- turbation to precipitation in the 1990s than that in the 1980s, which could be due to the interdecadal variation of anthropogenic emissions. 展开更多
关键词 AEROSOLS direct radiative effect climatic response interdecadal variation model simulation
下载PDF
Direct Climatic Effect of Dust Aerosol in the NCAR Community Atmosphere Model Version 3 (CAM3) 被引量:3
9
作者 乐旭 王会军 +1 位作者 廖宏 范可 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2010年第2期230-242,共13页
Direct climate responses to dust shortwave and longwave radiative forcing (RF) are studied using the NCAR Community Atmosphere Model Version 3 (CAM3). The simulated RF at the top of the atmosphere (TOA) is-0.45 ... Direct climate responses to dust shortwave and longwave radiative forcing (RF) are studied using the NCAR Community Atmosphere Model Version 3 (CAM3). The simulated RF at the top of the atmosphere (TOA) is-0.45 W m-2 in the solar spectrum and +0.09 W m-2 in the thermal spectrum on a global average. The magnitude of surface RF is larger than the TOA forcing, with global mean shortwave forcing of-1.76 W m-2 and longwave forcing of +0.31 W m-2 . As a result, dust aerosol causes the absorption of 1.1 W m-2 in the atmosphere. The RF of dust aerosol is predicted to lead to a surface cooling of 0.5 K over the Sahara Desert and Arabian Peninsula. In the meantime, the upper troposphere is predicted to become warmer because of the absorption by dust. These changes in temperature lead to a more stable atmosphere, which results in increases in surface humidity. The upward sensible and latent heat fluxes at the surface are reduced, largely balancing the surface energy loss caused by the backscattering and absorption of dust aerosol. Precipitation is predicted to decrease moderately on a global scale. 展开更多
关键词 dust aerosol radiative forcing direct radiative effect general circulation model
下载PDF
A numerical study of comparison of two one-state-variable,rate-and state-dependent friction evolution laws 被引量:2
10
作者 Jeen-Hwa Wang 《Earthquake Science》 CSCD 2009年第2期197-204,共8页
The two one-state-variable, rate- and state-dependent friction laws, i.e., the slip and slowness laws, are com- pared on the basis of dynamical behavior of a one-degree-of-freedom spring-slider model through numerical... The two one-state-variable, rate- and state-dependent friction laws, i.e., the slip and slowness laws, are com- pared on the basis of dynamical behavior of a one-degree-of-freedom spring-slider model through numerical simulations. Results show that two (normalized) model parameters, i.e., A (the normalized characteristic slip distance) and β-α (the difference in two normalized parameters of friction laws), control the solutions. From given values of △, β, and α, for the slowness laws, the solution exists and the unique non-zero fixed point is stable when △〉(β-α), yet not when △ 〈(β-α). For the slip law, the solution exists for large ranges of model parameters and the number and stability of the non-zero fixed points change from one case to another. Results suggest that the slip law is more appropriate for controlling earthquake dynamics than the slowness law. 展开更多
关键词 one-state-variable rate- and state-dependent friction law direct effect evolution effect characteristic slip displacement
下载PDF
Simulation of the Direct Radiative Effect of Mineral Dust and Sea Salt Aerosols in a Doubled Carbon Dioxide Climate 被引量:2
11
作者 YUE Xu LIAO Hong TANG Jin-Ping 《Atmospheric and Oceanic Science Letters》 CSCD 2013年第5期343-348,共6页
The authors examine the equilibrium climatic response to the direct radiative effect (DRE) of mineral dust and sea salt aerosols in a doubled-CO2 climate with two-way coupling of aerosol-climate interactions.In resp... The authors examine the equilibrium climatic response to the direct radiative effect (DRE) of mineral dust and sea salt aerosols in a doubled-CO2 climate with two-way coupling of aerosol-climate interactions.In response to the drier and windier conditions,dust emissions increase by 26% in the Sahara Desert and by 18% on the global scale relative to present day.Sea salt emissions increase in high latitudes (>60°) but decrease in middle latitudes (30°-60°) of both hemispheres due to the poleward shift of westerlies,leading to a 3% decrease in global emissions.The burdens of dust and sea salt increase by 31% and 7% respectively,because reductions in rainfall over the tropical oceans increase the lifetime of particles in the warmer climate.The higher aerosol loading in the doubled-CO2 climate reinforces aerosol DRE by -0.2 W m-2,leading to an additional cooling of 0.1℃ at the surface compared with the climatic effects of aerosols in present day.The additional cooling from changes in natural aerosols compensates for up to 15% of the regional warming induced by doubled CO2. 展开更多
关键词 mineral dust sea salt aerosol direct radiative effect
下载PDF
Dynamics and Responses of Vegetation to Climatic Variations in Ziya- Daqing Basins, China 被引量:1
12
作者 HUANG Farong MO Xingguo +1 位作者 LIN Zhonghui HU Shi 《Chinese Geographical Science》 SCIE CSCD 2016年第4期478-494,共17页
Examining the direct and indirect effects of climatic factors on vegetation growth is critical to understand the complex linkage between climate change and vegetation dynamics. Based on the Moderate Resolution Imaging... Examining the direct and indirect effects of climatic factors on vegetation growth is critical to understand the complex linkage between climate change and vegetation dynamics. Based on the Moderate Resolution Imaging Spectroradiometer(MODIS) Normalized Difference Vegetation Index(NDVI) data and meteorological data(temperature and precipitation) from 2001 to 2012, the trend of vegetation dynamics were examined in the Ziya-Daqing basins, China. The path analysis was used to obtain the information on the relationships among climatic factors and their effects on vegetation growth. It was found that the trends of growing season NDVI were insignificant in most plain dry land, while the upward trends were significant in forest, grass and dry land in Taihang Mountains. According to the path analysis, in 23% of the basins the inter-annual NDVI variation was dominated by the direct effect of precipitation, in 5% by the direct effects of precipitation and temperature, and in less than 1% by the direct effect of temperature or indirect effects of these two climatic factors. It indicated that precipitation significantly affected the vegetation growth in the whole basins, and this effect was not regulated by temperature. Precipitation increase(especially in July, August and September) was favorable to greenness enhancement. Summer temperature rising showed negative effect on plant productivity enhancement, but temperature rise in April was beneficial for the vegetation growth. When April temperature increases by 1℃, the onset date of greenness for natural vegetation will be 2 days in advance. There was a lag-time effect of precipitation or temperature on monthly NDVI for all land use types except grass. 展开更多
关键词 Normalized Difference Vegetation lndex (NDVI) PHENOLOGY climate variation direct effect indirect effect
下载PDF
Correlation of Direct Piezoelectric Effect on EAPap under Ambient Factors 被引量:1
13
作者 Li-Jie Zhao Chang-Ping Tang Peng Gong 《International Journal of Automation and computing》 EI 2010年第3期324-329,共6页
Direct piezoelectricity of electro-active papers (EAPap) is analysed in this paper. The test setups for direct effect are designed and determined. Different ambient factors impacting the piezoelectricity of EAPap, s... Direct piezoelectricity of electro-active papers (EAPap) is analysed in this paper. The test setups for direct effect are designed and determined. Different ambient factors impacting the piezoelectricity of EAPap, such as temperature, humidity, and strain rate, are applied and analyzed. Strong piezoelectricity of EAPap is found on the basis of the test results and in comparison with polyvinylidene fluoride (PVDF) and lead zirconate titanate (PZT)-5H. The maximum piezoelectric constant is achieved to be 504 pC/N. The reason of strong piezoelectricity of EAPap is discussed in this paper. The potential of EAPap as a biomimetic actuator and sensor is also investigated. 展开更多
关键词 Electro-active-polymer (EAP) electro-active papers (EAPap) biomimetic actuator PIEZOELECTRICITY direct piezoelectric effect.
下载PDF
Regional Oceanic Impact on Circulation and Direct Radiative Effect of Aerosol over East Asia 被引量:1
14
作者 XIONG Zhe HAN Zhi-Wei 《Atmospheric and Oceanic Science Letters》 2011年第6期324-329,共6页
The Regional Integrated Environmental Model System (RIEMS 2.0) coupled with a chemistry-aerosol model and the Princeton Ocean Model (POM) is employed to simulate regional oceanic impact on atmospheric circulation ... The Regional Integrated Environmental Model System (RIEMS 2.0) coupled with a chemistry-aerosol model and the Princeton Ocean Model (POM) is employed to simulate regional oceanic impact on atmospheric circulation and the direct radiative effect (DRE) of aerosol over East Asia. The aerosols considered in this study include both major anthropogenic aerosols (e.g., sulfate, black carbon, and organic carbon) and natural aerosols (e.g., soil dust and sea salt). The RIEMS 2.0 is driven by NCEP/NCAR reanalysis II, and the simulated period is from 1 January to 31 December 2006. The results show the following: (1) The simulated annual mean sea-level pressure by RIEMS 2.0 with POM is lower than without POM over the mainland and higher without POM over the ocean. (2) In summer, the subtropical high simulated by RIEMS 2.0 with POM is stronger and extends further westward, and the continental low is stronger than without POM in summer. (3) The aerosol optical depth (AOD) simulated by RIEMS 2.0 with POM is larger in the middle and lower reaches of the Yangtze River than without POM. (4) The direct radiative effect with POM is stronger than that without POM in the middle and lower reaches of the Yangtze River and parts of southern China. Therefore, the authors should take account of the impact of the regional ocean model on studying the direct climate effect &aerosols in long term simulation. 展开更多
关键词 aerosols direct radiative effect circulation regional ocean model the Regional Integrated Environ- mental Model System 2.0
下载PDF
THE OVERLOOKED ECOSYSTEM DRIVING FORCE IN NON-EUTROPHICATED FRESHWATER SYSTEMS:DISSOLVED HUMIC SUBSTANCES-A SHORT REVIEW AND OUTLOOK
15
作者 Christian E.W. Steinberg 《水生生物学报》 CAS CSCD 北大核心 2006年第6期721-733,共13页
This review starts with the description of the quantitative significance of dissolved organic material in general and dissolved humic substances (HS) in particular in various ecosystems. Despite their high quantities,... This review starts with the description of the quantitative significance of dissolved organic material in general and dissolved humic substances (HS) in particular in various ecosystems. Despite their high quantities, the knowledge about the role of HS is still very low and full of old, but still recycled paradigms. HS are thought to be inert or at least refractory and too large to be taken up by aquatic organisms. Instead, I present evidence that dissolved HS that mainly derives from the terrestrial environment, are taken up and directly and/or indirectly interfere with freshwater organisms and, thus, structure biocenoses. Relatively well known is in the meantime the fuelling function of allochthonous HS, which, upon irradiation, release fatty acids, which serve as substrates for microbial growth. This is an indirect effect of HS. Microbes, in turn, are food for mixotrophic algae and (heterotrophic) zooplankton. Thus, non-eutrophicated freshwaters are net-heterotrophic, meaning that respiration exceeds primary production. Furthermore, model calculations exemplify that only a very small portion of the terrestrial production is sufficient to cause net-heterotrophy in these freshwater bodies. But, recent papers show also that due to different stoichiometries the maximal plankton biomass production with algae or mixotrophs is higher than with bacteria. Very recently, several direct effects of HS have been elucidated. Among them are:induction of chaperons (stress shock proteins), induction and modulation of biotransformation enzymes, modulation (mainly inhibition) of photosynthetic oxygen release of aquatic plants, production of an internal oxidative stress, modulation of the offspring numbers in the nematode Caenorhabditis elegans[WTBZ], feminization of fish and amphibs, interference within the thyroid system, and action as chemical attractant to C. elegans. We are still in the phase of identifying the various physiological, biochemical, and molecular-biological effects. Hence, the ecological and ecophysiological significance of these HS-mediated effects still remain somewhat obscure. Nevertheless, HS appear generally to have an impact on the individual as well as on the community and even ecosystem level comparable to that of, for instance, nutrients. 展开更多
关键词 Humic substances Modulation of sex ratio Hormone-like effect Chemical attractant BIOTRANSFORMATION Oxidative stress Direct effects of humic substances Indirect effects of humic substances Net-heterotrophy Forest stocking
下载PDF
Near-fault ground motion bi-normalized pseudo-velocity spectra and its applications
16
作者 徐龙军Engineering College Ocean University of China 谢礼立 《Acta Seismologica Sinica(English Edition)》 CSCD 2007年第5期544-552,共9页
Ground motions with forward-directivity effect in the near-fault region are obviously different from ordinary far-field ground motions. Design spectral models for this kind of motions have been proposed by correlating... Ground motions with forward-directivity effect in the near-fault region are obviously different from ordinary far-field ground motions. Design spectral models for this kind of motions have been proposed by correlating simple pulses with parameters attenuation relationships in a previous study of the authors. To further test the applica- bility of the established design spectral model, we analyze ground motion pseudo-velocity response spectra (PVS), normalized pseudo-velocity spectra (NPVS) and bi-normalized pseudo-velocity spectra (BNPVS) of 53 typical near-fault forward-directivity ground motions. It is found that BNPVS not only has more salient features to reflect the difference between soil and rock sites, but also has less scattering to reveal the nature of forward-directivity motions. And then, BNPVS is used for prediction of design spectra accounting for the influence of site conditions, and the constructed design spectra are compared with those spectra established previously. It is concluded that site condition can heavily affect ground motions, buildings on rock can be even more dangerous than those on soil sites, in particular for ordinary buildings with short to middle vibration periods. Finally, pulse models are also suggested for structural analyses in the near-fault region. 展开更多
关键词 near-fault effect directivity effect PULSE pseudo-velocity spectrum design spectra
下载PDF
Characteristics of frequency content of near-fault ground motions during the Chi-Chi earthquake
17
作者 徐龙军 谢礼立 《Acta Seismologica Sinica(English Edition)》 EI CSCD 2005年第6期707-716,750,共11页
The frequency content of earthquake ground motion is very important because it affects the dynamic response of structural systems. In the paper, we use five scalar parameters (the response spectral predominant period ... The frequency content of earthquake ground motion is very important because it affects the dynamic response of structural systems. In the paper, we use five scalar parameters (the response spectral predominant period Tp, smoothed spectral predominant period To, Fourier amplitude spectral mean period Tm, equivalent pulse period Tv, and the pseudo-velocity spectral predominant period Tpv) reflecting the characteristics of frequency content of strong ground motion to examine the near-fault three-component motions during the 1999 Chi-Chi earthquake. The result indicates that the frequency content of near-fault motions at the Hanging wall is less than that at the foot wall; Tp shows a smaller value than that of To and Tm and it emerges a reverse relation of three-component motions as compared with that of To and Tm; Tv and Tpv of the near-fault motions at the north end of the rupture display a similar trend to that generated by the rupture directivity effect of strike-slip faulting. We therefore conclude that these observations are useful in the formulation of near-fault design spectra for seismic codes and in zoning studies in seismic risk. 展开更多
关键词 frequency content directivity effect hanging-wall effect Chi-Chi earthquake
下载PDF
The Effect of Magnetic Field on Resistivity of Hg_(0.89)Mn_(0.11)Te in Different Temperature Range
18
作者 王泽温 JIE Wanqi 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2015年第5期923-927,共5页
The resistivity of Hg<sub>0.89</sub>Mn<sub>0.11</sub>Te has been measured by the superconducting quantum interference device magnetometer in the temperature range from 5 to 200 K under the appl... The resistivity of Hg<sub>0.89</sub>Mn<sub>0.11</sub>Te has been measured by the superconducting quantum interference device magnetometer in the temperature range from 5 to 200 K under the applied magnetic field of 1, 2, 4 and 6.5 Tesla, respectively, compared with that of no-magnetic field. The results show that the resistivity increases with increase applied magnetic field at higher temperature from 80 to 200 K, but decreases at lower temperature from 5 to 25 K. There exists a transitive range from 25 to 80 K, where the variation of the resistivity shows different tendencies depending on the strength of magnetic field. Maximum difference of resistivity under 6.5 Tesla from that without magnetic field in the temperature range from 30 to 200 K is only about 5 Ω·cm, but it increases up to 3 orders of magnitude at 5 K. The analysis shows that the variation of resistivity of Hg<sub>0.89</sub>Mn<sub>0.11</sub>Te under the magnetic field is the algebraic sum of the transverse direction magnetoresistance effect and the sp-d exchange interaction effect. TDRME plays major role in the high temperature range. However, with the decrease of temperature, the effect of sp-d EI on the resistivity gradually exceeds that of the transverse direction magnetoresistance effect through the transitive range, and becomes the dominant effect in the temperature range from 5 to 25 K, which leads to the dramatic decrease of resistivity. 展开更多
关键词 Hg1-x Mnx Te RESISTIVITY MAGNETORESISTANCE transverse direction magnetoresistance effect sp-d exchange interaction effect
下载PDF
Impact of Direct Radiative Forcing of Anthropogenic Aerosols on Diurnal Temperature Range in January in Eastern China
19
作者 CHANG Wen-Yuan LIAO Hong 《Atmospheric and Oceanic Science Letters》 2011年第6期356-362,共7页
This study investigates the changes in January diurnal temperature range(DTR) in China during 1961-2000.The observed DTR changes during 1981-2000 relative to 1961-80 are first analyzed based on the daily temperature d... This study investigates the changes in January diurnal temperature range(DTR) in China during 1961-2000.The observed DTR changes during 1981-2000 relative to 1961-80 are first analyzed based on the daily temperature data at 546 weather stations.These observed DTR changes are classified into six cases depending on the changes in daily maximum and minimum temperatures,and then the occurrence frequency and magnitude of DTR change in each case are presented.Three transient simulations are then performed to understand the impact of greenhouse gases(GHGs) and aerosol direct forcing on DTR change:one without anthropogenic radiative forcing,one with anthropogenic GHGs,and another one with the combined forcing of GHGs and five species of anthropogenic aerosols.The predicted daily DTR changes during the years 1981-2000 are also classified into six cases and are compared with the observations.Results show that the previously proposed reason for DTR reduction,a stronger nocturnal warming than a daytime warming,explains only 19.8%of the observed DTR reduction days.DTR reductions are found to generally occur in northeastern China,coinciding with significant regional warming.The simulation with GHG forcing alone reproduces this type of DTR reduction with an occurrence frequency of 32.9%,which is larger than the observed value.Aerosol direct forcing reduces DTR mainly by daytime cooling.Consideration of aerosol cooling improves the simulation of occurrence frequencies of different types of DTR changes as compared to the simulation with GHGs alone,but it cannot improve the prediction of the magnitude of DTR changes. 展开更多
关键词 diurnal temperature range greenhouse gases anthropogenic aerosols aerosol direct effect
下载PDF
Environmental Taxes and Agriculture in the European Union and the Netherlands
20
作者 T. Toyoda 《Journal of Environmental Science and Engineering》 2011年第5期626-630,共5页
This paper analyzes the introduction of environmental taxes in the EU and Netherlands and their effects on agriculture, with a special focus on the background of the introduction of environmental tax systems, their de... This paper analyzes the introduction of environmental taxes in the EU and Netherlands and their effects on agriculture, with a special focus on the background of the introduction of environmental tax systems, their design concepts and effects on agriculture, the effects of fertilizer taxes in promoting sustainable agriculture, policy packages between environmental tax and environmental agreements, effects on globalization and global competitiveness, and conversion to renewable energy based on biomass resources. 展开更多
关键词 EU environmental taxes dutch glasshouse horticulture renewable energy and biomass environmental agreements(covenants) direct effects and dynamic effect.
下载PDF
上一页 1 2 3 下一页 到第
使用帮助 返回顶部