全文获取类型
收费全文 | 9838篇 |
免费 | 113篇 |
国内免费 | 93篇 |
专业分类
安全科学 | 283篇 |
废物处理 | 460篇 |
环保管理 | 1245篇 |
综合类 | 1193篇 |
基础理论 | 2667篇 |
环境理论 | 2篇 |
污染及防治 | 2771篇 |
评价与监测 | 708篇 |
社会与环境 | 667篇 |
灾害及防治 | 48篇 |
出版年
2022年 | 100篇 |
2021年 | 76篇 |
2020年 | 65篇 |
2019年 | 72篇 |
2018年 | 145篇 |
2017年 | 139篇 |
2016年 | 229篇 |
2015年 | 164篇 |
2014年 | 237篇 |
2013年 | 742篇 |
2012年 | 296篇 |
2011年 | 440篇 |
2010年 | 362篇 |
2009年 | 396篇 |
2008年 | 470篇 |
2007年 | 475篇 |
2006年 | 424篇 |
2005年 | 366篇 |
2004年 | 323篇 |
2003年 | 375篇 |
2002年 | 324篇 |
2001年 | 503篇 |
2000年 | 331篇 |
1999年 | 192篇 |
1998年 | 137篇 |
1997年 | 133篇 |
1996年 | 138篇 |
1995年 | 162篇 |
1994年 | 125篇 |
1993年 | 102篇 |
1992年 | 123篇 |
1991年 | 118篇 |
1990年 | 130篇 |
1989年 | 130篇 |
1988年 | 94篇 |
1987年 | 87篇 |
1986年 | 65篇 |
1985年 | 90篇 |
1984年 | 89篇 |
1983年 | 86篇 |
1982年 | 82篇 |
1981年 | 73篇 |
1980年 | 61篇 |
1979年 | 68篇 |
1977年 | 53篇 |
1976年 | 48篇 |
1975年 | 53篇 |
1974年 | 51篇 |
1973年 | 53篇 |
1970年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
981.
The results of a study on morphophysiological variation in fish inhabiting a subarctic lake exposed to chronic industrial pollution are described using an example of cisco, Coregonus lavaretus. It is shown that indices of the heart, liver, kidneys, gills, and fatness in these fish are increased significantly and have retained increased values for the past 20 years. The observed changes are analyzed on the basis of biochemical data. The results of studies on the dynamics of hematological parameters in fish are used for characterizing the development of toxicosis. Adaptive rearrangements associated with an increase in the metabolic rate and the activation of protective systems in the fish are explained in the context of S.S. Schvarts' concept. The idea is proposed that the additional energy cost of detoxification may be responsible for morphophysiological variation in fish under conditions of water pollution. 相似文献
982.
H. Cornier-Ríos P. A. Sundaram J. T. Celorie 《Journal of Polymers and the Environment》2007,15(1):51-56
Recycled plastics are considered low performance materials because their properties are expected to decrease drastically with
recycling. The objective of this study was to characterize a 15 wt.% glass filled polyethylene terephthalate (rPET-15GF) using
six recycle generations and four recycle ratios. Mechanical properties such as tensile strength, elastic modulus, and percent
elongation to failure of the PET composite were determined for various recycle generations and recycle ratios. Results show
that the mechanical properties of rPET-15GF decrease slightly per recycle generation. In contrast, thermal properties of rPET-15GF
were not at all affected by the recycling process. This data demonstrates that recycled glass filled PET can be used effectively
to fabricate components without significantly affecting their mechanical performance. 相似文献
983.
J. Marsalek T. M. Dick P. E. Wisner W. G. Clarke 《Journal of the American Water Resources Association》1975,11(2):306-328
ABSTRACT: Three urban runoff models, namely, the Road Research Laboratory Model (RRLM), the Storm Water Management Model (SWMM) and the University of Cincinnati Urban Runoff Model (UCURM), were examined by comparing the model simulated hydrographs with the hydrographs measured on several instrumented urban watersheds. This comparison was done for the hydrograph peak points as well as for the entire hydrographs using such statistical measures as the correlation coefficient, the special correlation coefficient and the integral square error. The results of the study indicated that, when applying the three selected non-calibrated models on small urban catchments, the SWM model performed marginally better than the RRL model and both these models were more accurate than the UCUR model. On larger watersheds, the comparisons between the SWM model and the other two models would be likely even more favourable for the SWM model, because it has the most advanced flow routing scheme among the studied models. 相似文献
984.
Paired water samples were simultaneously activated from two different vertical positions within the approach section of a flow-control structure to determine the effect of sample intake position on nonpoint runoff parameter concentrations and subsequent event loads. Suspended solids (SS), total phosphorus (TP) and organic plus exchangeable nitrogen [(Or+Ex)-N] were consistently higher throughout each runoff event when sampled from the floor of the approach section as opposed to those samples taken at midstage. Dissolved molybdate reactive phosphorus (DMRP) and ammonium (NH4-N) concentrations did not appear to be significantly affected by the vertical difference in intake position. However, the nitrate plus nitrite nitrogen [(NO3+NO2)-N] concentrations were much higher when sampled from the midstage position.Although the concentration differences between the two methods were not appreciable, when evaluated in terms of event loads, discrepancies were evident for all parameters. Midstage sampling produced event loads for SS, TP, (Or + Ex)–N, DMRP, NH4-N, and (NO3+NO2)-N that were 44,39,35,80,71, and 181%, respectively, of floor sampling loads. Differences in loads between the two methods are attributed to the midstage position, sampling less of the bed load. The correct position will depend on the objective; however, such differences should be recognized during the design phase of the monitoring program.This work was supported by the Soil Science Department, College of Agriculture and Life Sciences, University of Wisconsin-Madison, and by the U.S. Environmental Protection Agency, Region V., Chicago, Illinois (Grant No. G005139-01). 相似文献
985.
Harold E. Marshall Rosalie T. Ruegg 《Journal of the American Water Resources Association》1976,12(5):903-917
ABSTRACT: The Environmental Protection Agency administers a construction grant program to encourage abatement of wastewater pollution by sharing with municipalities the costs of wastewater treatment facilities. The enabling legislation (P.L. 92–500) specifies that EPA's cost share will be 75% of construction costs. It further requires municipalities to collect user fees from industrial users of the facilities to repay that part of the federal grant allocable to the treatment of industrial wastewater. The municipality must return half of the user fees collected to the U.S. Treasury; the municipality is allowed to retain the remaining half. Retention by municipalities of these user fees lowers their effective cost shares and results in the following consequences: (1) a bias for municipalities to select certain kinds of abatement techniques regardless of whether or not they are the least-cost techniques from the national perspective; (2) a bias for municipalities to select larger-than-optimal scales of abatement facilities; (3) a hidden federal subsidy to industry; and (4) grants that favor industrial communities. This article examines the legislative and regulatory requirements for user charges, derives the algebraic expressions for calculating the real federal, municipal, and industrial cost shares with user fees; computes municipal cost shares for selected values of the determinant factors; evaluates efficiency and other consequences of current user fee arrangements; and concludes that the efficiency distortions brought about by the impacts of user fees on cost sharing could be eliminated by requiring that all user fees collected from industry against the federal cost share be returned to the U.S. Treasury. 相似文献
986.
J. L. Hanisch B. R. Hart W. S. Turetsky H. T. Garabedian G. H. Pain 《Environmental management》1978,2(2):127-133
The body of information presented in this paper is directed to air pollution engineers who are concerned with the effect of indirect sources on ambient concentrations of carbon monoxide (CO). Data taken under controlled conditions are used to empirically derive and calibrate a model for predicting CO concentrations in the vicinity of roadway intersections and other points of possible vehicular congestion. Since the predicted free flow CO contribution of vehicles traveling at normal road speeds is relatively low, it is concluded that idling vehicles at points of congestion are the major cause of CO violations, and that state and federal programs should place more emphasis on relieving congestion and reducing idling emission rates in new vehicles. 相似文献
987.
The information presented in this paper is directed to air pollution engineers who are concerned with monitoring Carbon Monoxide. This paper evaluates systems for CO sampling under conditions where the receptor is located at intersections within 40 meters of the road edge. Non-Dispersive Infrared and electrochemical analysis techniques are used in conjunction with continuous recording, continuous bag sampling, and meter readings at 5 second intervals. The relative accuracy of each system is examined and the conditions for which each system is best suited are described. 相似文献
988.
T. C. Daniel P. E. McGuire G. D. Bubenzer F. W. Madison J. G. Konrad 《Environmental management》1978,2(1):55-65
Planning considerations to be evaluated early in the design of water quality monitoring programs are reviewed. These criteria emphasize the importance of isolating the study area, parameter section, and type of measurements required to ensure meaningful results. A demonstration automatic water quality monitoring program is described. Details with respect to type of equipment, coordination of component parts, sampling program, and analysis of specific parameters are reviewed. General costs of implementation and maintenance of such programs are presented. 相似文献
989.
Albert Rango Arthur T. Anderson 《Journal of the American Water Resources Association》1974,10(5):1060-1081
ABSTRACT. The Spring 1973 Mississippi River flood was investigated using remotely sensed data from ERTS-1. Both manual and automatic analyses of the data indicate that ERTS-I is extremely useful as a regional tool for flood management. Quantitative estimates of area flooded were made in St. Charles County, Missouri and Arkansas. Flood hazard mapping was conducted in three study areas along the Mississippi River using pre-flood ERTS-1 imagery enlarged to 1:250,000 and 1:100,000 scale. The flood prone areas delineated on these maps correspond to areas that would be inundated by significant flooding (approximately the 100 year flood). The flood prone area boundaries were generally in agreement with flood hazard maps produced by the U. S. Army Corps of Engineers and U. S. Geological Survey although the latter are somewhat more detailed because of their larger scale. Initial results indicate that ERTS-1 digital mapping of flood prone areas can be performed at 1:62,500 which is comparable to some conventional flood hazard map scales. 相似文献
990.
I. N. Sukhanova M. V. Flint G. Hibaum V. Karamfilov A. I. Kopylov E. Matveeva T. N. Rat'kova A. F. Sazhin 《Marine Biology》1988,99(1):1-8
The structure and some functional characteristics of the plankton community at the time of aExuviaella cordata red tide were investigated in Burgas Bay, Bulgaria, in May and June 1986. Characteristics of main plankton components (phyto-, bacterio-, nanoheterotrophic plankton, ciliates and mesoplankton) in the bloom area are presented. Development of theE. cordata bloom was determined by abiotic conditions among which eutrophication and salinity decrease caused the patchy character of its rapid development. Attainment of maximum red tide (ca. 1x109 cells l-1; 1x103 g m-3) from background (500 to 800x103 cells l-1; 600 mg m-3) took 3 to 7d. Growth rate () during that period was 1.2 to 2.2 doublings per day. A sharp bloom decline (3 to 4d) was caused by parasitic flagellates destroying the alga's chloroplast. Diel biomass losses due to grazing remained below 5%. Metabolites and degradation products ofE. cordata revealed no pronounced toxic effects on the other components of the planktonic community. The rapid bloom degradation due to the effects of parasitic flagellates indicates the high potential of ecosystem self-regulation. 相似文献