全文获取类型
收费全文 | 2753篇 |
免费 | 77篇 |
国内免费 | 31篇 |
专业分类
安全科学 | 124篇 |
废物处理 | 116篇 |
环保管理 | 814篇 |
综合类 | 281篇 |
基础理论 | 650篇 |
环境理论 | 1篇 |
污染及防治 | 595篇 |
评价与监测 | 162篇 |
社会与环境 | 83篇 |
灾害及防治 | 35篇 |
出版年
2023年 | 15篇 |
2022年 | 22篇 |
2021年 | 29篇 |
2020年 | 20篇 |
2019年 | 34篇 |
2018年 | 52篇 |
2017年 | 49篇 |
2016年 | 72篇 |
2015年 | 61篇 |
2014年 | 58篇 |
2013年 | 293篇 |
2012年 | 111篇 |
2011年 | 145篇 |
2010年 | 116篇 |
2009年 | 124篇 |
2008年 | 161篇 |
2007年 | 148篇 |
2006年 | 129篇 |
2005年 | 97篇 |
2004年 | 80篇 |
2003年 | 100篇 |
2002年 | 86篇 |
2001年 | 56篇 |
2000年 | 47篇 |
1999年 | 24篇 |
1998年 | 43篇 |
1997年 | 28篇 |
1996年 | 38篇 |
1995年 | 46篇 |
1994年 | 31篇 |
1993年 | 44篇 |
1992年 | 36篇 |
1991年 | 15篇 |
1990年 | 24篇 |
1989年 | 17篇 |
1988年 | 25篇 |
1987年 | 15篇 |
1986年 | 19篇 |
1985年 | 30篇 |
1984年 | 23篇 |
1983年 | 24篇 |
1982年 | 34篇 |
1981年 | 34篇 |
1980年 | 32篇 |
1979年 | 21篇 |
1978年 | 23篇 |
1977年 | 11篇 |
1976年 | 8篇 |
1974年 | 7篇 |
1972年 | 9篇 |
排序方式: 共有2861条查询结果,搜索用时 625 毫秒
371.
Kenneth L. Ladd Jr. Richard Chambers Sherry Kunka Dale Harmon 《Environment international》1981,6(1-6)
In October 1977, Southwestern Public Service Company executed a contract with the U.S. Environmental Protection Agency that called for a study to assess the performance of a fabric filter system installed on a large utility boiler that utilizes low sulfur Western coal. The project is now into its second year and the objectives of this paper are to describe the scope and intent of the study, as well as to report progress to date. In addition, some of the difficulties that we have encountered are discussed. Although some of these problems have resulted in procedural changes, the intent of the study has not been altered. This paper describes work being done in specific areas with which both the EPA and Southwestern are connected. These include fabric assessment, data collection, selection and installation of instrumentation, and overall fabric filter system performance. Results of the first performance test are also reviewed and the installation of a pilot baghouse is discussed. 相似文献
373.
Richard H. Hawkins 《Journal of the American Water Resources Association》1975,11(5):887-890
ABSTRACT: Storm runoff as calculated by the runoff curve number method is shown to be of varying sensitivity to both input rainfall and curve number. Using an assumed input error of 10%, a runoff error chart is given. Up to about 9 inches of rainfall, runoff is more sensitive to curve number than to rainfall. The importance of accurate curve number selection in this range is stressed. 相似文献
374.
375.
376.
Two iodometric methods for the concentration and analysis of water samples containing organic oxidants were applied to rivers and wastewaters in Illinois, Delaware, and Pennsylvania. Oxidant concentrations detected were as high as 2.5 § 10−5 M; the methods were capable of detecting as little as 10−8 M. Compounds possibly responsible for the observed oxidizing activity include N-chloro compounds, organic peroxides, or quinones. 相似文献
377.
378.
Richard H. McCuen Walter J. Rawls Bob L. Whaley 《Journal of the American Water Resources Association》1979,15(4):935-947
ABSTRACT: While the correlation coefficient and standard error of estimate are frequently used when comparing models of seasonal water yield, the following criteria may be more important in selecting one model from among several alternatives: rationality of the regression coefficients, the distribution of the residual errors, and the correctness of indicators of the relative importance of the predictor variables. These criteria were used to compare seasonal water yield models that were calibrated using multiple regression, stepwise regression, principal components regression, polynomial regression using a principal components rotation, and constrained pattern search. Hydrologic data from the Upper Sevier River basin in southern Utah were used to illustrate the comparative analysis process. The prediction equations used the April-July streamflow volume as the criterion variable. 相似文献
379.
Richard J. Perkins 《Ecological modelling》1978,5(1):1-15
Using a recently developed technique, a realistic method of introducing species into an evolving ecosystem simulation model is presented. A single unit, preemption strength, provides an index which combines strictly preemptive and strictly head-of-the-line colonization strategies. An optimization of priority strategies is presented. The relevance of the realistically evolving model to the stability-complexity problem is emphasized. 相似文献
380.
Connell DP Withum JA Winter SE Statnick RM Bilonick RA 《Journal of the Air & Waste Management Association (1995)》2005,55(5):559-573
One-hour average ambient concentrations of particulate matter (PM) with an aerodynamic diameter < 2.5 microm (PM2.5) were determined in Steubenville, OH, between June 2000 and May 2002 with a tapered element oscillating microbalance (TEOM). Hourly average gaseous copollutant [carbon monoxide (CO), sulfur dioxide (SO2), nitrogen oxide (NOx), and ozone (O3)] concentrations and meteorological conditions also were measured. Although 75% of the 14,682 hourly PM2.5 concentrations measured during this period were < or = 17 microg/m3, concentrations > 65 microg/m3 were observed 76 times. On average, PM2.5 concentrations at Steubenville exhibited a diurnal pattern of higher early morning concentrations and lower afternoon concentrations, similar to the diurnal profiles of CO and NO(x). This pattern was highly variable; however, PM2.5 concentrations > 65 microg/m3 were never observed during the mid-afternoon between 1:00 p.m. and 5:00 p.m. EST. Twenty-two episodes centered on one or more of these elevated concentrations were identified. Five episodes occurred during the months June through August; the maximum PM2.5 concentration during these episodes was 76.6 microg/m3. Episodes occurring during climatologically cooler months often featured higher peak concentrations (five had maximum concentrations between 95.0 and 139.6 microg/m3), and many exhibited strong covariation between PM2.5 and CO, NO(x), or SO2. Case studies suggested that nocturnal surface-based temperature inversions were influential in driving high nighttime concentrations of these species during several cool season episodes, which typically had dramatically lower afternoon concentrations. These findings provide insights that may be useful in the development of PM2.5 reduction strategies for Steubenville, and suggest that studies assessing possible health effects of PM2.5 should carefully consider exposure issues related to the intraday timing of PM2.5 episodes, as well as the potential for toxicological interactions among PM2.5, and primary gaseous pollutants. 相似文献