全文获取类型
收费全文 | 41474篇 |
免费 | 452篇 |
国内免费 | 359篇 |
专业分类
安全科学 | 1357篇 |
废物处理 | 1867篇 |
环保管理 | 5641篇 |
综合类 | 6374篇 |
基础理论 | 10993篇 |
环境理论 | 11篇 |
污染及防治 | 10379篇 |
评价与监测 | 2818篇 |
社会与环境 | 2570篇 |
灾害及防治 | 275篇 |
出版年
2022年 | 346篇 |
2021年 | 417篇 |
2020年 | 267篇 |
2019年 | 351篇 |
2018年 | 604篇 |
2017年 | 627篇 |
2016年 | 988篇 |
2015年 | 701篇 |
2014年 | 1095篇 |
2013年 | 3362篇 |
2012年 | 1328篇 |
2011年 | 1785篇 |
2010年 | 1477篇 |
2009年 | 1509篇 |
2008年 | 1862篇 |
2007年 | 1824篇 |
2006年 | 1671篇 |
2005年 | 1416篇 |
2004年 | 1437篇 |
2003年 | 1362篇 |
2002年 | 1269篇 |
2001年 | 1581篇 |
2000年 | 1095篇 |
1999年 | 663篇 |
1998年 | 532篇 |
1997年 | 529篇 |
1996年 | 552篇 |
1995年 | 639篇 |
1994年 | 591篇 |
1993年 | 510篇 |
1992年 | 539篇 |
1991年 | 514篇 |
1990年 | 511篇 |
1989年 | 502篇 |
1988年 | 434篇 |
1987年 | 374篇 |
1986年 | 362篇 |
1985年 | 366篇 |
1984年 | 406篇 |
1983年 | 395篇 |
1982年 | 409篇 |
1981年 | 361篇 |
1980年 | 273篇 |
1979年 | 315篇 |
1978年 | 269篇 |
1977年 | 226篇 |
1975年 | 231篇 |
1974年 | 221篇 |
1973年 | 243篇 |
1972年 | 242篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
Integration of Environmental Assessment into the Regional Development Planning Process of the Galilee 总被引:2,自引:0,他引:2
/ The Galilee region on the northern edge of Israel constitutes more than 15% of the state's territory, supplies more than half of its drinking water needs, and is an important recreational resource and destination for Israelis. One of the main objectives of the plan for the Galilee was to devise a regional physical and economic development strategy for the years 1992-2007 that would arrest the trend of emigration of its residents, attract newly arrived immigrants to the region, and at the same time protect natural resources and environmental quality. This paper is limited to discussion of the environmental aspects of the plan. It analyzes spatial concepts for distribution of projected population growth, evaluates environmental impacts of alternative plans, and proposes a decision-making framework and tools for minimizing natural resources loss from development at the local level. Assessment of potential environmental impacts generated quantitative data of natural resources areas. Application of the data in the plan evaluation stage showed that the alternative that concentrated most of the new development in central Galilee was the second-best choice environmentally, but was preferred as the best choice for overall qualities. The planning study offers an alternative environmental impact assessment (EIA) process to the one presently used in Israel by incorporating environmental considerations at the initial plan-making stage and not at the plan-approval stage. It demonstrated that in order to be effective, environmental assessment and land-use planning should be seen as one effort that is integrated from the start and in each stage of the plan-making process.KEY WORDS: Environmental assessment; Development planning; Galilee 相似文献
152.
153.
Summary Pesticide residues in soil, water, food, wildlife and other media have been analysed in several monitoring studies. The purpose was to establish the distribution of these residues across a defined area, ascertain their trend over a specific period and use the results to assess environmental compliance and safety. In the present review the availability of information on pesticide residues in various Canadian environmental components was sought. With the possible exception of localized pesticide contamination of some private water supply wells, ground and surface water, most analyses revealed concentrations below guideline limits. Only a few cases were reported of mishandling, misuse and poisoning from pesticides. Continuing surveillance programmes and in-depth and well-organized monitoring studies, with special focus on areas that are vulnerable to contamination, by both provincial and federal governments, are largely responsible for the encouraging results. This experience in the control of pesticide use and monitoring of residues in the environment should be of particular interest in developing countries.Dr A.Y. Sangodoyin is a senior lecturer in the Department of Agricultural Engineering at the University of Ibadan. He was recently involved in a study visit to the University of Alberta, Edmonton, Alberta, Canada T6G 2G7, where his co-author Dr D.W. Smith is a member of staff in the Department of Civil-Engineering. 相似文献
154.
Barry D. Keim Gregory E. Faiers 《Journal of the American Water Resources Association》1996,32(1):117-124
ABSTRACT: In most studies, quantile estimates of extreme 24-hour rainfall are given in annual probabilities. The probability of experiencing an excessive storm event, however, differs throughout the year. As a result, this paper explored the differences between heavy rainfall distributions by season in Louisiana. It was concluded by using the Kruskal-Wallis and Mann-Whitney tests that the distribution of heavy rainfall events differs significantly between particular seasons at the sites near the Gulf Coast. Furthermore, seasonal frequency curves varied dramatically at the four sites examined. Mixed distributions within these data were not found to be problematic, but the mechanisms that produced the events were found to change seasonally. Extreme heavy rainfall events in winter and spring were primarily generated by frontal weather systems, while summer and fall events had high proportions of events produced by tropical disturbances and airmass (free-convective) conditions. 相似文献
155.
156.
Peggy A. Johnson Thomas M. Heil 《Journal of the American Water Resources Association》1996,32(6):1283-1291
ABSTRACT: Bankfull depth and discharge are basic input parameters to stream planform, stream restoration, and highway crossing designs, as well as to the development of hydraulic geometry relationships and the classification of streams. Unfortunately, there are a wide variety of definitions for bankfull that provide a range of values, and the actual selection of bankfull is subjective. In this paper, the relative uncertainty in determining the bankfull depth and discharge is quantified, first by examining the variability in the estimates of bankfull and second by using fuzzy numbers to describe bankfull depth. Fuzzy numbers are used to incorporate uncertainty due to vagueness in the definition of bankfull and subjectivity in the selection of bankfull. Examples are provided that demonstrate the use of a fuzzy bankfull depth in sediment trans. port and in stream classification. Using fuzzy numbers to describe bankfull depth rather than a deterministic value allows the engineer to base designs and decisions on a range of possible values and associated degrees of belief that the bankfull depths take on each value in that range. 相似文献
157.
L. A. Kelly J. Stellwagen A. Bergheim 《Journal of the American Water Resources Association》1996,32(5):1017-1025
ABSTRACT: Recent studies suggest that waste generation from the freshwater phase of Atlantic salmon (Salmo salar L.) production varies considerably on an annual basis. A fish farm on the West Coast of Scotland was visited regularly during a two-year period to determine inflow and outflow water quality. Waste output budgets of suspended solids (SS), biochemical oxygen demand (BOD), total nitrogen (TN), total phosphorus (TP), total ammonia nitrogen (TAN = NH3+NH4+), dissolved reactive phosphorus (DRP) and total phosphorus (TP) were produced. The annual waste loadings obtained were 71 kg TN t fish?1 yr?1 (one year of data only), 10.9–11.1 kg TP t fish?1 yr?1, 1.2–2.1 kg DRP t fish?1 yr?1, 422–485 kg BOD5 t fish?1 yr?1, 327–337 kg SS t fish?1 yr?1, and 30–35 kg TAN-N t fish?1 yr?1. Simple linear regression models relating waste parameter production to water temperature and feeding regime were developed. When compared to existing data for other salmonid production systems, greater ranges of daily waste loadings were observed. Wide variations in concentrations of these parameters during a daily cycle were also observed, suggesting that mass balance estimates of waste production will provide more robust estimates of waste output than frequent monitoring of outflow water quality. 相似文献
158.
Car manufacturers must eliminate automotive shredder residues (ASR). Two ways of incineration are of interest: at 850°C in municipal waste incinerators or at higher temperatures, above 1100°C in cement plants. These processes reduce the mass and the volume of waste to be disposed of in landfills and energy recovery might be possible. Regulations govern the emission of gaseous effluents to control environmental risk. To determine gaseous effluents from a pilot sacle or an industrial incineration plant, an artificial ASR was made by mixing three representative organic polymers present in the real ASR, namely polyvinylchloride, polyurethane and rubber. This mixture was incinerated at 850 and 1100°C in laboratory experiments and the analyses of the principal gaseous effluents such as carbon oxides, nitrogen oxides, volatile organic compounds, hydrochloric and hydrocyanic acids and sulphur compounds are presented and discussed. Lastly, in order to simulate artificial ASR behaviour, the composition of the combustion gases at equilibrium was calculated using a Gibbs energy minimisation code. 相似文献
159.
Groundwater was being remediated with pump and treat technology at a facility where the groundwater was contaminated with commonly used degreaser solvents. Hydraulic conductivity of the heterogeneous residuum was beneficiated by applying pneumatic fracturing technology. The remedial system was controlled and monitored by a sophisticated remote telemetry system. A case history follows. 相似文献
160.
Elvis G. Ngwenya Maud Walsh Caroline A. Metosh‐Dickey Ralph J. Portier 《补救:环境净化治理成本、技术与工艺杂志》2006,16(2):79-90
Biological and physicochemical approaches were utilized in a treatment train for acid mine dis charge (AMD) waters. Anaerobic bioreactors, chemical precipitation reactors, and biopolymer chelation reactors, operated in static, semicontinuous, and continuous flow modes, removed significant quantities of metals and sulfates associated with AMD water. Static tests indicated accept able copper removal via precipitation by generation of hydrogen sulfide in anaerobic reactors. However, low pH affected the biopolymer coating in the chelation reactor, resulting in loss of bed surface. Corrections of AMD to pH > 7 resulted in some metal precipitationprior to biopolymer treatment. A series of static semicontinuous tests at pH 5.0 provided improved metal and sulfate removal. Copper (Cu+) was reduced to trace concentrations, while manganese (Mn+), although reduced, proved to be the most recalcitrant of the metals. © 2006 Wiley Periodicals, Inc. 相似文献