全文获取类型
收费全文 | 28177篇 |
免费 | 234篇 |
国内免费 | 255篇 |
专业分类
安全科学 | 653篇 |
废物处理 | 1143篇 |
环保管理 | 3211篇 |
综合类 | 6324篇 |
基础理论 | 6577篇 |
环境理论 | 11篇 |
污染及防治 | 7033篇 |
评价与监测 | 1950篇 |
社会与环境 | 1651篇 |
灾害及防治 | 113篇 |
出版年
2022年 | 221篇 |
2021年 | 220篇 |
2019年 | 190篇 |
2018年 | 378篇 |
2017年 | 380篇 |
2016年 | 573篇 |
2015年 | 439篇 |
2014年 | 704篇 |
2013年 | 1979篇 |
2012年 | 798篇 |
2011年 | 1118篇 |
2010年 | 877篇 |
2009年 | 984篇 |
2008年 | 1125篇 |
2007年 | 1174篇 |
2006年 | 1054篇 |
2005年 | 921篇 |
2004年 | 898篇 |
2003年 | 909篇 |
2002年 | 838篇 |
2001年 | 1130篇 |
2000年 | 714篇 |
1999年 | 516篇 |
1998年 | 309篇 |
1997年 | 346篇 |
1996年 | 366篇 |
1995年 | 387篇 |
1994年 | 382篇 |
1993年 | 332篇 |
1992年 | 341篇 |
1991年 | 355篇 |
1990年 | 340篇 |
1989年 | 288篇 |
1988年 | 303篇 |
1987年 | 240篇 |
1986年 | 257篇 |
1985年 | 255篇 |
1984年 | 268篇 |
1983年 | 266篇 |
1982年 | 274篇 |
1981年 | 249篇 |
1980年 | 205篇 |
1979年 | 201篇 |
1978年 | 213篇 |
1977年 | 184篇 |
1976年 | 180篇 |
1975年 | 175篇 |
1974年 | 202篇 |
1971年 | 169篇 |
1967年 | 190篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
951.
Eric G. Walther 《Journal of the Air & Waste Management Association (1995)》2013,63(5):352-355
The available national annual air pollution emissions are based on mass. Different air pollutants have greatly different toxicities per unit mass, hence the emissions should be rated by effect, not by mass, so that more sensible priorities can be set in control research and regulation. Effect factors are derived from the health effect literature indirectly by using the national ambient air quality standards. The resulting analysis by effects shows transportation to be still the largest source as it is in the mass analysis while hydrocarbons become the largest pollutants by effect compared to carbon monoxide being the largest pollutant by mass. 相似文献
952.
J.M. Heuss G.J. Nebel J.M. Colucci 《Journal of the Air & Waste Management Association (1995)》2013,63(9):535-548
The recently promulgated national air quality standards for carbon monoxide, nitrogen dioxide, hydrocarbons, and photochemical oxidant are critically reviewed.This review indicates that the standards are more restrictive than can be supported by available data. 相似文献
953.
V. Withstandley W.J. Moroz G.W. Anderson 《Journal of the Air & Waste Management Association (1995)》2013,63(9):571-573
A portable, battery-operated, electro-optical dust analyzer operating on the principle of light scattering from individual dust particles in air drawn through a high-intensity light field has been developed for monitoring dust levels where external power may be unavailable. The instrument counts and size-discriminates airborne particles over two size ranges upwards of 0.3 microns with immediate readout. A dilution mechanism permits analysis of particulate concentrations as high as 2400 particles/cm3 on each channel. The self-contained Ni-Cd batteries are rechargeable. Total weight, including batteries and all components, is approximately 14 Ib. Total power used, mainly for pumping a filtered air sheath at 300 cm/sec and for the light source, is less than 34 watts. Another unique feature is the flow system designed for turbulence suppression. Electronic calibration in terms of number of particles/cm3 for each size range is accomplished in the laboratory by means of a pulse generator with respect to which the readout indicator is calibrated for count. The input voltages to the pulse-height discriminators are appropriately attenuated for various pulse amplitudes simulating the output of the light-sensitive pickup, a photomultiplier tube.Pulse height as a function of particle size was measured for polystyrene latex beads ranging from 0.3 to 2 microns in diameter. Good correlation is obtained with results from commercial analyzers. Field surveys have been undertaken with the CAES prototype analyzer at various sites in central Pennsylvania and at numerous sampling points within the cities of Pittsburgh and Philadelphia. Particulate concentrations as high as 1400 particles/ cm3 have been measured at a coal cleaning plant. 相似文献
954.
N.C.G. Freeman T. Wainman P.J. Lioy A.H. Stern S.I. Shupack 《Journal of the Air & Waste Management Association (1995)》2013,63(8):604-605
Honorary Memberships are conferred by the Air Pollution Control Association on persons of widely recognized eminence in some part of the field of air pollution control or who have rendered especially meritorious service to the Association. Honorary Memberships were awarded this year to Dr. Leonard Greenburg and Mr. Milton Reizenstein, both past presidents of APCA. 相似文献
955.
David G. McFarland Joseph W. DeNardo Walter G. Popiel 《Journal of the Air & Waste Management Association (1995)》2013,63(12):825-827
Verification of forecasts of COH levels at the Downtown Sampling Station using our objective forecast method developed in conjunction with the Allegheny County Bureau of Air Pollution Control gave excellent results. The next step was to expand the area of forecast coverage. COH data taken from July 1968 through June 1969 from six sampling stations located roughly in a large concentric arc around the Downtown Station were studied. Three of the stations are located in river valleys near large industrial plants and the other three are located on higher terrain in suburban areas. COH levels of Low, Moderate, High, and Very High (where Low = 0–0.9, Moderate = 1.0–1.9, High = 2.0–3.0, and Very High = >3.0) were used. The total number of occurrences of High and Very High COHS at the Downtown Station was 10.7% of the total data sample. This was more than twice the frequency of any of the outlying stations. An evaluation of the statistical frequencies indicate the Downtown Station can safely be used as a “control station” in forecasting Low or Moderate COH levels for the six surrounding stations. However, the occurrence of High or Very High COH levels at the six outlying stations do not occur with a high enough statistical consistency to be predicted by using the forecast value of the Downtown Station. The valley stations exhibit the characteristics of separate sub air basins particularly during a period in which morning inversions occur for two or more consecutive days and the average daily wind speed does not exceed 4 m/sec. The results show it is possible to forecast only Low or Moderate COH levels for each of the six outlying stations by using statistical correlations derived from the Downtown Station. Separate objective forecasts which relate the pollution buildup in each valley sub air basin must be used when High or Very High COHS are forecast at the Downtown Station. 相似文献
956.
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
957.
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
958.
Laurel J. Staley Marta K. Richards George L. Huffman Robert A. Olexsey Barry Dellinger 《Journal of the Air & Waste Management Association (1995)》2013,63(3):321-331
Measurements conducted on full-scale hazardous waste incinerators have occasionally shown a relationship between carbon monoxide (CO) emissions and emissions of toxic organic compounds. In this study, four mixtures of chlorinated C1 and C2 hydrocarbons were diluted in commercial-grade heptane and burned in a water-cooled turbulent flame reactor (TFR) under two different excess air levels. No correlation between CO and organic emissions could be discerned. Reasons for this lack of observable correlations are discussed in terms of combustion and chemical reaction kinetic theory. 相似文献
959.
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
960.
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