全文获取类型
收费全文 | 619篇 |
免费 | 6篇 |
国内免费 | 25篇 |
专业分类
安全科学 | 26篇 |
废物处理 | 87篇 |
环保管理 | 57篇 |
综合类 | 81篇 |
基础理论 | 91篇 |
环境理论 | 1篇 |
污染及防治 | 226篇 |
评价与监测 | 58篇 |
社会与环境 | 19篇 |
灾害及防治 | 4篇 |
出版年
2023年 | 10篇 |
2022年 | 8篇 |
2021年 | 10篇 |
2020年 | 7篇 |
2019年 | 11篇 |
2018年 | 20篇 |
2017年 | 31篇 |
2016年 | 28篇 |
2015年 | 18篇 |
2014年 | 25篇 |
2013年 | 58篇 |
2012年 | 33篇 |
2011年 | 48篇 |
2010年 | 34篇 |
2009年 | 45篇 |
2008年 | 43篇 |
2007年 | 41篇 |
2006年 | 42篇 |
2005年 | 30篇 |
2004年 | 31篇 |
2003年 | 14篇 |
2002年 | 15篇 |
2001年 | 13篇 |
2000年 | 7篇 |
1999年 | 4篇 |
1998年 | 5篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1985年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有650条查询结果,搜索用时 15 毫秒
511.
In this paper the Elder problem is studied with the purpose of evaluating the inherent instabilities associated with the numerical solution of this problem. Our focus is first on the question of the existence of a unique numerical solution for this problem, and second on the grid density and fluid density requirements necessary for a unique numerical solution. In particular we have investigated the instability issues associated with the numerical solution of the Elder problem from the following perspectives: (i) physical instability issues associated with density differences; (ii) sensitivity of the numerical solution to idealization irregularities; and, (iii) the importance of a precise velocity field calculation and the association of this process with the grid density levels that is necessary to solve the Elder problem accurately. In the study discussed here we have used a finite element Galerkin model we have developed for solving density-dependent flow and transport problems, which will be identified as TechFlow. In our study, the numerical results of Frolkovic and de Schepper [Frolkovic, P. and H. de Schepper, 2001. Numerical modeling of convection dominated transport coupled with density-driven flow in porous media, Adv. Water Resour., 24, 63-72.] were replicated using the grid density employed in their work. We were also successful in duplicating the same result with a less dense grid but with more computational effort based on a global velocity estimation process we have adopted. Our results indicate that the global velocity estimation approach recommended by Yeh [Yeh, G.-T., 1981. On the computation of Darcian velocity and mass balance in finite element modelling of groundwater flow, Water Resour. Res., 17(5), 1529-1534.] allows the use of less dense grids while obtaining the same accuracy that can be achieved with denser grids. We have also observed that the regularity of the elements in the discretization of the solution domain does make a difference in obtaining a unique stationary solution for this problem. The results of our study also indicate that the density differences are critical in the solution of the Elder problem and that high density differences lead to the physical instability that is inherent with this problem. Other than the physical instability associated with the level of density differences used in the Elder problem, the following two points should be considered in solving the Elder problem in a consistent manner: (i) strict attention should be paid to the vertical grid Peclet number in developing the criteria for convergent grid selection; and, (ii) with a globally continuous velocity calculation stable solutions can be obtained at lower grid densities. 相似文献
512.
Choi JW Lee W Lee DB Park CH Kim JS Jang YH Kim Y 《Environmental monitoring and assessment》2007,129(1-3):37-42
The immobilized cell using self-assembled synthetic oligopeptide was applied to the electrochemical detection of pathogen
infection. Thin films based on cysteine-terminated synthetic oligopeptides were fabricated for the immobilization of HeLa
cell on gold (Au) substrate. Layer formation and immobilization of the cell were investigated with surface plasmon resonance
(SPR) and electrochemical impedance spectroscopy (EIS). Experimental results showed that the thin film of cysteine-terminated
synthetic oligopeptide was successfully fabricated and it could be applied for the immobilization of HeLa cells. The adhered
living cell was exposed to E. coli O157:H7, which induced the change of SPR angle and electrochemical impedance signal. The proposed cell immobilization method
using self-assembly technique can be applied to construct the cell microarray for on-site pathogen monitoring. 相似文献
513.
Wajih Ur Rehman Minhan Park Jihyo Chong Kwangyul Lee Jiho Jang 《Environmental Forensics》2020,21(1):48-58
AbstractTo determine the sources of particulate matter less than 2.5?μm (PM2.5 in different ambient atmospheres (urban, roadside, industrial, and rural sites), the chemical components of PM2.5 such as ions (Cl-, NO3-, SO42-, NH4+, Na+, K+, Ca2+, and Mg2+), carbonaceous species, and elements (Al, As, Ba, Cd, Cu, Fe, Mn, Ni, Pb, Se, V, and Zn) were measured. The average mass concentrations of PM2.5 at the urban, roadside, industrial, and rural sites were 31.5?±?14.8, 31.6?±?22.3, 31.4?±?16.0, and 25.8?±?12.4?μg/m3, respectively. Except for secondary ammonium sulfate and ammonium nitrate, the model results showed that the traffic source (i.e., the sum of gasoline and diesel vehicle sources) was the most dominant source of PM2.5 (17.1%) followed by biomass burning (13.8%) at the urban site. The major primary sources of PM2.5 were consistent with the site characteristics (diesel vehicle source at the roadside site, coal-fired plants at the industrial site, and biomass burning at the rural site). Seasonal data from the urban site suggested that ammonium sulfate and ammonium nitrate were the most dominant sources of PM2.5 during all seasons. Further, the contribution of road dust source to PM2.5 increased during spring and fall seasons. We conclude that the determination of the major PM2.5 sources is useful for establishing efficient control strategies for PM2.5 in different regions and seasons. 相似文献
514.
AlThuwaynee Omar F. Kim Sang-Wan Najemaden Mohamed A. Aydda Ali Balogun Abdul-Lateef Fayyadh Moatasem M. Park Hyuck-Jin 《Environmental science and pollution research international》2021,28(32):43544-43566
Environmental Science and Pollution Research - This study investigates uncertainty in machine learning that can occur when there is significant variance in the prediction importance level of the... 相似文献
515.
516.
517.
Kim Eunjung Gil Hyungbae Park Sangwon Park Jinwon 《Journal of Material Cycles and Waste Management》2017,19(1):423-431
Journal of Material Cycles and Waste Management - Slow pyrolysis is characterized by a low heating rate and high reaction time. The products are bio-char, bio-oil and bio-gas. In bio-oil, there are... 相似文献
518.
Ning Wang Jaeyoung Park Timothy G. Ellis 《Journal of Material Cycles and Waste Management》2014,16(3):475-481
The adsorption capacity of fine rubber particle media (FRPM) derived from discarded vehicle tires and the consumer wasted rubber sources was evaluated for hydrogen sulfide treatment. H2S breakthrough tests were performed at various zinc contents, temperatures, and packing quantities. High zinc concentrations increased the adsorption capacity of FRPM significantly. H2S removal by FRPM was optimized at a packing quantity of 75 % of the column volume, and the adsorption capacity increased with reactor temperature within the range of 20–85 °C. The regeneration of ZnCl2 solution was reliable for increasing regeneration capacity of the FRPM-adsorbed H2S. FRPM seems to be an attractive alternative of H2S adsorbents in terms of cost effectiveness compared to traditional materials. 相似文献
519.
C. R. Unelius K.-C. Park M. McNeill S. L. Wee B. Bohman D. M. Suckling 《Die Naturwissenschaften》2013,100(2):135-143
An investigation to identify a sex or aggregation pheromone of Sitona discoideus Gyllenhål (Coleoptera: Curculionidae) is presented. Antenna flicking and attraction behaviors evoked by conspecifics of both sexes were recorded in arena bioassays, where attraction of females to males was observed. Air entrainment of both males and females was conducted in separate chambers. Gas chromatographic–mass spectrometric analysis of headspace volatiles revealed that two male-specific compounds, 4-methyl-3,5-heptanedione (major) and (4S,5S)-5-hydroxy-4-methyl-3-heptanone (minor), were emitted during the autumnal post-aestivatory flight period. The stereoisomers of the minor component were separated by enantioselective gas chromatography and their absolute configurations assigned by NMR (diastereomers) and the known preference of enantioselective transesterification reactions catalyzed by Candida antarctica lipase B. Electroantennogram and single sensillum recording studies indicate that 4-methyl-3,5-heptanedione as well as all individual stereoisomers of 5-hydroxy-4-methyl-3-heptanone are detected by the antennae of male and female S. discoideus. Further, single sensillum recordings suggest that both sexes of S. discoideus have specialized olfactory receptor neurons (ORNs) for detecting 4-methyl-3,5-heptanedione and different populations of stereoselective ORNs for detecting the stereoisomers of 5-hydroxy-4-methyl-3-heptanone. Some of these stereoselective ORNs appear to be sex-specific in S. discoideus. 相似文献
520.
Structural Change of the Manufacturing Sector in Korea: Measurement of Real Energy Intensity and CO2 Emissions 总被引:1,自引:0,他引:1
Jung Tae Yong Park Tae Sik 《Mitigation and Adaptation Strategies for Global Change》2000,5(3):221-238
In terms of energy use, it is wellknown that energy intensity in the manufacturingsector is higher than any other sector. In Korea, theenergy intensity of the manufacturing sector hasdeteriorated since the late 1980s. This phenomenonis quite unique compared with the trend of energyintensity in other countries. In this study, weclosely examine the structural composition of Korea'smanufacturing sector from 1981 to 1996, its energyintensity, and its implications for carbon dioxide(CO2) emissions by introducing the measurement ofreal energy intensity.The conventional index of energy intensity is notappropriate for aggregate industries. Since theaggregation of industries in the manufacturing sectorincludes structural change, it would be better toseparate the effect of structural change. Hence, inthis study, we apply a decomposition methodology forenergy intensity based on the `Divisia Index'. Ateach industry level, energy intensity is a mixedmeasurement of pure energy efficiency improvement andfuel substitution. We also calculate real energyintensity at each industry level. Based on ouranalysis, we derive carbon dioxide (CO2) intensity and analyze the factors that affect CO2 emission in this sector.During 1988–1993, the energy intensity of themanufacturing sector in Korea deteriorated. Industrial structural change,the real energy intensity in this sector became evenworse during this period. The primary reason for thisphenomenon was that the share of energy intensiveindustries, such as steel, cement, and petro-chemicalindustries increased. Second, during the sameperiod, liquefied natural gas (LNG) rapidlypenetrated this sector, so that theCO2 intensity improved. We find thatharmonization of economic development strategies andenvironmental consideration is crucial for sustainabledevelopment. Based on our study, we derived somepolicy implications. Integration of industrialpolicies and energy efficiency improving programs isquite important, as well as the acceleration of fuelsubstitution to less carbon (C) intensive ones. Integration of local and global environmental policiesplays an important role for mitigatingCO2 emissions. 相似文献