全文获取类型
收费全文 | 28745篇 |
免费 | 278篇 |
国内免费 | 237篇 |
专业分类
安全科学 | 664篇 |
废物处理 | 1170篇 |
环保管理 | 3442篇 |
综合类 | 5691篇 |
基础理论 | 7232篇 |
环境理论 | 10篇 |
污染及防治 | 7234篇 |
评价与监测 | 1900篇 |
社会与环境 | 1784篇 |
灾害及防治 | 133篇 |
出版年
2022年 | 219篇 |
2021年 | 208篇 |
2019年 | 197篇 |
2018年 | 365篇 |
2017年 | 393篇 |
2016年 | 592篇 |
2015年 | 468篇 |
2014年 | 718篇 |
2013年 | 2125篇 |
2012年 | 828篇 |
2011年 | 1179篇 |
2010年 | 987篇 |
2009年 | 1024篇 |
2008年 | 1188篇 |
2007年 | 1253篇 |
2006年 | 1092篇 |
2005年 | 925篇 |
2004年 | 933篇 |
2003年 | 928篇 |
2002年 | 877篇 |
2001年 | 1122篇 |
2000年 | 766篇 |
1999年 | 498篇 |
1998年 | 325篇 |
1997年 | 372篇 |
1996年 | 384篇 |
1995年 | 413篇 |
1994年 | 416篇 |
1993年 | 361篇 |
1992年 | 366篇 |
1991年 | 359篇 |
1990年 | 359篇 |
1989年 | 335篇 |
1988年 | 293篇 |
1987年 | 286篇 |
1986年 | 276篇 |
1985年 | 280篇 |
1984年 | 295篇 |
1983年 | 287篇 |
1982年 | 276篇 |
1981年 | 247篇 |
1980年 | 230篇 |
1979年 | 231篇 |
1978年 | 207篇 |
1977年 | 212篇 |
1976年 | 165篇 |
1975年 | 175篇 |
1974年 | 193篇 |
1973年 | 176篇 |
1972年 | 164篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
F.L. Voelz S.I. Weinberg B.G. Gower 《Journal of the Air & Waste Management Association (1995)》2013,63(12):935-942
Gross average automotive exhaust emissions data collected by the Atlantic Richfield Clean Air Caravan during the summer of 1970 showed only slight geographical variations when the specific makes were ignored. When considering specific makes, significant differences were found on an average emissions basis. Vehicle population—emission distributions showed wide variations in the 50% population levels and in the percent of vehicles with emissions greater than specified values. Hydrocarbon (HC) and carbon monoxide (CO) data are given on a gross basis for the 1970, 1968-69, 1966-67, and pre-1966 model year group vehicles. Average HC and CO emissions and vehicle population-Idle emissions distribution curves are included for specific make vehicles in selected areas. 相似文献
942.
D. V. Sandberg S. G. Pickford E. F. Darley 《Journal of the Air & Waste Management Association (1995)》2013,63(3):278-281
Pollutants sampled during the burning of 30 lb ponderosa pine fuel beds yielded emission factors for CO, hydrocarbon gases, and par-ticulate matter of 146, 8.4, and 9.1 lb/ton of fuel, respectively. When similar beds were treated with diammonium phosphate flame retardant, these factors increased to 166, 11.7, and 19.3 lb/ton of fuel, respectively. Gas chromatographic analysis of hydrocarbon gases showed that 15-40% of this material was composed of methane and eth-ylene. Ethane and acetylene were the next most abundant materials, with photochemically important materials constituting minor portions of this gaseous component. Fuel beds treated with flame retardant produced more oiefins, and this production lasted throughout the smoldering phase of burning. These tests showed that the smoldering phase of combustion is of major importance to air pollutant production during slash burning. The initial 80% of the fuel burned accounted for only 20-30% of HC and CO emissions. This suggests that a rapid mop-up of slash burns could substantially reduce air pollutant production. 相似文献
943.
R. A. Stoehr J. P. Pezze 《Journal of the Air & Waste Management Association (1995)》2013,63(11):1119-1122
The evolution of H2S and SO2 from hot blast furnace slags by reaction with H2O has been found to be dependent upon the presence of O2 or H2 in the reaction zone as well as on the temperature. H2 has been found to produce a small increase in H2S and a small decrease in SO2 emission, while O2 has been found to produce a very great inhibiting effect on H2S emission and only a small increase in SO2 emission. The total emission of sulfur bearing gases is much less when H2O + air is blown at the slag than when H2O + Ar is blown at the slag, particularly at 1200°C and above. These effects may be useful in attempts to design systems for slag quenching which will produce less pollution. 相似文献
944.
William W. Moyer Fred P. Osman 《Journal of the Air & Waste Management Association (1995)》2013,63(11):1155-1157
Portable air quality monitoring systems may be required to supplement fixed installations or to provide for quick response to a transient situation, possibly at a remote location. A microprocessor-based monitoring unit has been developed for use with existing sensors. The unit is portable and its operational sequence can be programmed to adapt it to any unique requirements existing at the deployment site. Selectable on-site calculations are performed on raw data, and a hard copy or tape record of results can be produced. 相似文献
945.
Richard G. Rhoads 《Journal of the Air & Waste Management Association (1995)》2013,63(12):1203-1206
The initial state implementation plans concentrated on attainment of the ambient air quality standards in the relatively polluted areas of the country. Many of these plans must now be modified to ensure that the ambient standards will be maintained for the foreseeable future, and to ensure that significant deterioration of air quality in clean areas of the country is prevented. The existing implementation plans currently contain many measures which are applicable to the maintenance and deterioration efforts, but additional measures must also be developed. Many of these additional measures will involve future planning activities—most common of which will be land use planning activities. The point is made that, after existing sources have reduced their emissions to the lowest practical level, further air pollution control can only be accomplished by implementing rational planning procedures for management of any new sources of air pollution. This will require extensive cooperation among the air pollution control community; regional, state, and local planning agencies; state and local governments; and the general public in order to ensure that future land use plans include appropriate air quality considerations. 相似文献
946.
R. D. Steele G. C. Page G. F. Meenaghan 《Journal of the Air & Waste Management Association (1995)》2013,63(6):634-635
Reference methods for the determination of mercury emissions from stationary sources typically include collection of mercury by solutions which are acidic and oxidizing. In the presence of high levels of SO2 the oxidizing capacity of these absorbing solutions will be degraded and the collection efficiency for mercury compromised. This seriously limits the usefulness of the reference methods as they apply to the mining and smelting industries. In the present work peroxide is used to remove SO2 and acidic permanganate is used to collect mercury. At a mean sampling rate of 10 L/min concentrations of at least 12 mg/m3 mercury can be satisfactorily collected in the presence of up to 20,000 ppm SO2. 相似文献
947.
948.
Joseph D. McCain John P. Gooch Wallace B. Smith 《Journal of the Air & Waste Management Association (1995)》2013,63(2):117-121
This paper presents results of source size distribution measurements over the size range from 0.1 μm to 5 μm for six classes of particulate sources and fractional efficiency measurements on five full scale electrostatic precipitators and one pilot scale precipitator. The precipitators all showed moderately high to high particulate collection efficiencies for particles having diameters larger than a few micrometers or smaller than a few hundredths of a micrometer and a minimum in collection efficiency for particles having diameters of a few tenths of a micrometer. 相似文献
949.
Susanna B. Levitt David P. Chock 《Journal of the Air & Waste Management Association (1995)》2013,63(11):1091-1092
Pollutant data from the Los Angeles Basin were analyzed for weekday-weekend differences for the smog months of June through September 1972 and 1973. The pollutants investigated were oxidant, NO, NO2, total hydrocarbons (HC), CO, and particulates. In order to maintain the diurnal variation, the concentration percentiles were calculated for each weekday and weekend hour. 相似文献
950.
D.P. Hoult S.R. O'Dea G.L. Touchton R.J. Ketterer 《Journal of the Air & Waste Management Association (1995)》2013,63(1):56-60
Plume rise downwind of a large stationary gas turbine was measured in the field and the conditions were then scaled in the laboratory. For the laboratory, the plume exit conditions, wind velocity and temperature profiles, and wind direction were matched. It was found that for high temperature exhaust, the buoyancy is best matched by calculating a dimensionless density difference. With properly calculated buoyancy length scales, the plume trajectories were compared and were found to agree quite well. The probability distributions of the entrainment constant and the average values of the entrapment constant with downwind distance were compared. The field data showed about 15% greater plume rise. The median entrainment constant was about 10% greater for the lab test and the shape of the probability distribution matched very closely. 相似文献