全文获取类型
收费全文 | 21431篇 |
免费 | 210篇 |
国内免费 | 214篇 |
专业分类
安全科学 | 603篇 |
废物处理 | 1044篇 |
环保管理 | 2637篇 |
综合类 | 2784篇 |
基础理论 | 5553篇 |
环境理论 | 4篇 |
污染及防治 | 5872篇 |
评价与监测 | 1737篇 |
社会与环境 | 1491篇 |
灾害及防治 | 130篇 |
出版年
2023年 | 103篇 |
2022年 | 223篇 |
2021年 | 231篇 |
2020年 | 157篇 |
2019年 | 194篇 |
2018年 | 348篇 |
2017年 | 348篇 |
2016年 | 551篇 |
2015年 | 390篇 |
2014年 | 605篇 |
2013年 | 1904篇 |
2012年 | 719篇 |
2011年 | 917篇 |
2010年 | 835篇 |
2009年 | 823篇 |
2008年 | 946篇 |
2007年 | 1040篇 |
2006年 | 916篇 |
2005年 | 757篇 |
2004年 | 754篇 |
2003年 | 740篇 |
2002年 | 702篇 |
2001年 | 928篇 |
2000年 | 647篇 |
1999年 | 407篇 |
1998年 | 295篇 |
1997年 | 258篇 |
1996年 | 303篇 |
1995年 | 278篇 |
1994年 | 267篇 |
1993年 | 248篇 |
1992年 | 247篇 |
1991年 | 217篇 |
1990年 | 222篇 |
1989年 | 228篇 |
1988年 | 204篇 |
1987年 | 171篇 |
1986年 | 133篇 |
1985年 | 147篇 |
1984年 | 176篇 |
1983年 | 156篇 |
1982年 | 203篇 |
1981年 | 141篇 |
1980年 | 126篇 |
1979年 | 158篇 |
1978年 | 123篇 |
1977年 | 111篇 |
1976年 | 104篇 |
1975年 | 85篇 |
1974年 | 92篇 |
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
991.
Seymour Calvert Dale Lundgren Dilip S. Mehta 《Journal of the Air & Waste Management Association (1995)》2013,63(7):529-532
The object of this program was to study particle collection efficiency in venturi scrubbers in order to account for the effects of particle size and wettability, venturi size, and fluid flow rates. The body of information is directed to those interested in the prediction of particle collection efficiency in venturi scrubbers. 相似文献
992.
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
993.
Donald S. Shepard 《Journal of the Air & Waste Management Association (1995)》2013,63(11):756-761
Load-shifting, a relatively inexpensive approach to air pollution control, involves transferring the generating load from one power plant to another according to meteorological conditions. In this paper, an atmospheric dispersion model is adapted to estimate the exposure of the urban population to sulfur dioxide from operating the power system in different ways. Then a mathematical model of the power system of a metropolitan area is constructed to determine the reduction in pollution exposure which could be achieved, and the costs involved. As a case study, the application of the model to St. Louis, Missouri, is simulated. Under favorable conditions, load shifting could reduce pollution exposure up to 95%, while increasing the costs of electric power generation by only 4%. The load-shifting model has use not only as an operational control strategy, but also as an analytical tool to evaluate alternative pollution control measures in the electric power industry. 相似文献
994.
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
995.
996.
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
997.
Joseph B. Knox Rolf Lange 《Journal of the Air & Waste Management Association (1995)》2013,63(1):48-53
With the development of ambient air quality standards (AAQS), the need arises to describe the characteristics of regional surface air-pollutant concentration frequency distributions. In the evaluation of land use plans, numerous agencies will be concerned with evaluating the effectiveness of emission zoning and/or control actions. On a regional basis, one means of performing this assessment lies in determining the changes in the pollutant frequency distributions resulting from control actions. This study presents new data concerning the surface air-pollutant concentration frequency distributions observed for area sources and continuous point sources, and compares these distributions with those of the pertinent meteorological variables describing the transport and diffusion of the pollutant. The observed surface air pollutant frequency distributions are compared to those corresponding to simple modeling concepts from either an urban area source or a continuous point source. For an urban source and a relatively inert pollutant like CO, we found that the observed frequency distribution for CO surface air concentration parallels the approximately log-normal frequency distribution of the reciprocal of the wind speed. We show that the constant relating these two well-correlated frequency distributions can be determined either experimentally or with a numerical simulation model of air pollution. The usefulness of numerical models in air pollution is discussed. 相似文献
998.
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
999.
J. M. Genco H. S. Rosenberg M. Y. Anastas E. C. Rosar J. M. Dulin 《Journal of the Air & Waste Management Association (1995)》2013,63(12):1244-1253
This paper describes some technical and economic aspects of the nahcolite ore injection process for the simultaneous removal of fly ash and sulfur oxides from stack gases. The process is capable of removing greater than 99% of the particulate matter and greater than 70% of the sulfur oxides present in such gases. In the process, nahcolite ore, a naturally occurring material containing 70 to 90% sodium bicarbonate, is ground to 90% passing through —200 mesh screens. Approximately 20% of the ground ore is used to precoat the filter bags in a baghouse filter while the remainder of the material is fed into the flue gas Just ahead of the baghouse. The flue gas is drawn through the baghouse by induced draft fans and sent up the stack. Most of the SO2 and practically all of the fly ash in the flue gas can be removed as the gas passes through the filter bags. The spent nahcolite ore and fly ash are collected and conveyed to waste disposal as landfill, or alternatively processed for insolubilization by coprecipitation prior to landfilling. The technical feasibility of the process has been demonstrated in both bench scale and pilot scale engineering studies. Economic analyses performed for the cases of plants located in the midwest and southwest indicate lower capital costs for the nahcolite injection process when compared to wet scrubbing. On an annual cost basis, the nahcolite ore Injection process is comparable in cost to wet scrubbing for the case of the southwestern power plant, and somewhat more expensive for the case of the midwestern plant. 相似文献
1000.
Keshava S. Murthy Harvey S. Rosenberg Richard B. Engdahl 《Journal of the Air & Waste Management Association (1995)》2013,63(9):851-855
Fourteen sulfur and/or sulfuric acid producing regenerate FGD processes were discussed at the 1974 FGD Symposium in Atlanta. During the period elapsed since then, considerable status change has occurred on many of these regenerable processes. Other regenerable processes which were not as well known during 1974 have surfaced in 1975. The problems of obtaining reducing gases (hydrogen sulfide, carbon monoxide, and hydrogen) for the reduction of sulfur dioxide product streams to elemental sulfur have become severe due to shortages of natural gas or other petroleum based feedstock. A new sulfur producing process which employs CO and H2 directly (rather than the H2S required for liquid and vapor base Claus reactions) is gaining attention. This paper discusses briefly: (1) the announced status of the many regenerable FGD processes, (2) the problem of reductant gas supply, and (3) the effect on FGD processes of using coal based reducing gas instead of reformed natural gas. 相似文献