全文获取类型
收费全文 | 722篇 |
免费 | 13篇 |
国内免费 | 11篇 |
专业分类
安全科学 | 42篇 |
废物处理 | 31篇 |
环保管理 | 239篇 |
综合类 | 54篇 |
基础理论 | 155篇 |
污染及防治 | 130篇 |
评价与监测 | 62篇 |
社会与环境 | 27篇 |
灾害及防治 | 6篇 |
出版年
2023年 | 3篇 |
2021年 | 3篇 |
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 13篇 |
2017年 | 16篇 |
2016年 | 12篇 |
2015年 | 19篇 |
2014年 | 14篇 |
2013年 | 49篇 |
2012年 | 19篇 |
2011年 | 34篇 |
2010年 | 24篇 |
2009年 | 25篇 |
2008年 | 48篇 |
2007年 | 27篇 |
2006年 | 43篇 |
2005年 | 33篇 |
2004年 | 32篇 |
2003年 | 33篇 |
2002年 | 19篇 |
2001年 | 23篇 |
2000年 | 23篇 |
1999年 | 12篇 |
1998年 | 5篇 |
1997年 | 12篇 |
1996年 | 10篇 |
1995年 | 10篇 |
1994年 | 11篇 |
1993年 | 14篇 |
1992年 | 13篇 |
1991年 | 9篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 9篇 |
1986年 | 8篇 |
1985年 | 9篇 |
1984年 | 9篇 |
1983年 | 9篇 |
1982年 | 11篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1978年 | 7篇 |
1977年 | 9篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1972年 | 3篇 |
1971年 | 5篇 |
1970年 | 3篇 |
排序方式: 共有746条查询结果,搜索用时 62 毫秒
251.
Chemical solutions for greywater recycling 总被引:1,自引:0,他引:1
Pidou M Avery L Stephenson T Jeffrey P Parsons SA Liu S Memon FA Jefferson B 《Chemosphere》2008,71(1):147-155
Greywater recycling is now accepted as a sustainable solution to the general increase of the fresh water demand, water shortages and for environment protection. However, the majority of the suggested treatments are biological and such technologies can be affected, especially at small scale, by the variability in strength and flow of the greywater and potential shock loading. This investigation presents the study of alternative processes, coagulation and magnetic ion exchange resin, for the treatment of greywater for reuse. The potential of these processes as well as the influence of parameters such as coagulant or resin dose, pH or contact time were investigated for the treatment of two greywaters of low and high organic strengths. The results obtained revealed that magnetic ion exchange resin and coagulation were suitable treatment solutions for low strength greywater sources. However, they were unable to achieve the required level of treatment for the reuse of medium to high strength greywaters. Consequently, these processes could only be considered as an option for greywater recycling in specific conditions that is to say in case of low organic strength greywater or less stringent standards for reuse. 相似文献
252.
Positive Feedbacks among Forest Fragmentation, Drought, and Climate Change in the Amazon 总被引:2,自引:0,他引:2
Abstract: The Amazon basin is experiencing rapid forest loss and fragmentation. Fragmented forests are more prone than intact forests to periodic damage from El Niño–Southern Oscillation ( ENSO) droughts, which cause elevated tree mortality, increased litterfall, shifts in plant phenology, and other ecological changes, especially near forest edges. Moreover, positive feedbacks among forest loss, fragmentation, fire, and regional climate change appear increasingly likely. Deforestation reduces plant evapotranspiration, which in turn constrains regional rainfall, increasing the vulnerability of forests to fire. Forest fragments are especially vulnerable because they have dry, fire-prone edges, are logged frequently, and often are adjoined by cattle pastures, which are burned regularly. The net result is that there may be a critical "deforestation threshold" above which Amazonian rainforests can no longer be sustained, particularly in relatively seasonal areas of the basin. Global warming could exacerbate this problem if it promotes drier climates or stronger ENSO droughts. Synergisms among many simultaneous environmental changes are posing unprecedented threats to Amazonian forests. 相似文献
253.
Bruce R. James 《Environmental geochemistry and health》2001,23(3):175-179
254.
Jia-Yeong Ku Huiting Mao Kesu Zhang Kevin Civerolo S. Trivikrama Rao C. Russell Philbrick Bruce Doddridge Richard Clark 《Environmental Fluid Mechanics》2001,1(2):209-233
This paper examines the effects of two different planetary boundary-layer (PBL) parameterization schemes – Blackadar and Gayno–Seaman – on the predicted ozone (O3) concentration fields using the MM5 (Version 3.3) meteorological model and the MODELS-3 photochemical model. The meteorological fields obtained from the two boundary-layer schemes have been used to drive the photochemical model to simulate O3 concentrations in the northeastern United States for a three-day O3 episodic period. In addition to large differences in the predicted O3 levels at individual grid cells, the simulated daily maximum 1-h O3 concentrations appear at different regions of the modeling domain in these simulations, due to the differences in the vertical exchange formulations in these two PBL schemes. Using process analysis, we compared the differences between the different simulations in terms of the relative importance of chemical and physical processes to O3 formation and destruction over the diurnal cycle. Finally, examination of the photochemical model's response to reductions in emissions reveals that the choice of equally valid boundary-layer parameterizations can significantly influence the efficacy of emission control strategies. 相似文献
255.
Numerical Investigation of Boundary-Layer Evolution and Nocturnal Low-Level Jets: Local versus Non-Local PBL Schemes 总被引:3,自引:0,他引:3
Kesu Zhang Huiting Mao Kevin Civerolo Stephen Berman Jia-Yeong Ku S. Trivikrama Rao Bruce Doddridge C. Russell Philbrick Richard Clark 《Environmental Fluid Mechanics》2001,1(2):171-208
Numerical simulations of the evolution of the planetary boundary layer (PBL) and nocturnal low-level jets (LLJ) have been carried out using MM5 (version 3.3) with four-dimensional data assimilation (FDDA) for a high pollution episode in the northeastern United States during July 15–20, 1999. In this paper, we assess the impact of different parameterizations on the PBL evolution with two schemes: the Blackadar PBL, a hybrid local (stable regime) and non-local (convective regime) mixing scheme; and the Gayno–Seaman PBL, a turbulent kinetic energy (TKE)-based eddy diffusion scheme. No FDDA was applied within the PBL to evaluate the ability of the two schemes to reproduce the PBL structure and its temporal variation. The restriction of the application of FDDA to the atmosphere above the PBL or the lowest 8 model levels, whichever is higher, has significantly improved the predicted strength and timing of the LLJ during the night. A systematic analysis of the PBL evolution has been performed for the primary meteorological fields (temperature, specific humidity, horizontal winds) and for the derived parameters such as the PBL height, virtual potential temperature, relative humidity, and cloud cover fraction. There are substantial differences between the PBL structures and evolutions simulated by these two different schemes. The model results were compared with independent observations (that were not used in FDDA) measured by aircraft, RASS and wind profiler, lidar, and tethered balloon platforms during the summer of 1999 as part of the NorthEast Oxidant and Particle Study (NE-OPS). The observations tend to support the non-local mixing mechanism better than the layer-to-layer eddy diffusion in the convective PBL. 相似文献
256.
Agar BJ Baetz BW Wilson BG 《Journal of the Air & Waste Management Association (1995)》2007,57(3):348-354
The methodology laid out in this paper shows that typical operational data from vehicle fleets monitored by a global positioning system (GPS) can be used to estimate heavy-duty diesel vehicle (HDDV) emissions, thereby enabling waste managers and governing bodies to internalize the responsibility for socioenvironmental costs traditionally absorbed by external parties. Although municipal solid waste (MSW) collection vehicles are the subjects of this particular study, the methodology presented here can be applied to any fleet of vehicles monitored by GPS. This study indicates that MSW collection trucks may be considerably less fuel efficient in the field than published values for HDDV fuel efficiency suggest. The average fuel efficiency of one MSW collection truck was estimated as 0.90 +/- 0.44 km/L (2.12 +/- 1.03 mi/gal). This same truck would generate approximately 42 metric tons of CO2 equivalents/yr, which is comparable to the greenhouse gas emissions of a large sport utility vehicle driving six times the distance, in town, for a year. In terms of the impacts such emissions have, projections for the monetary cost of emissions are available but highly variable. They suggest that the external monetary costs of emissions range between 6 and 39% of the annual fuel costs for the studied MSW collection truck. The results of this study indicate a need for further research into valuation of the hidden, external costs of emissions, borne by local and global socioecological communities. The possible implications of this result include poorly advised fleet procurement decisions and underestimation of MSW collection fleet emissions. 相似文献
257.
258.
259.
Toshihide Hamazaki Bruce C. Thompson Brian A. Locke Kenneth G. Boykin 《Journal of Environmental Planning and Management》2003,46(2):239-256
In developing conservation strategies, it is important to maximize effects of conservation within a specified land tract and to maximize conservation effects on surrounding area (ecological context). The authors proposed two criteria to select biotic entities for conservation foci: (1) the relative occurrence of fauna or flora in a tract is greater than that of an ecological context region; and (2) occurrence of the fauna or flora is relatively limited in the ecological context region. Using extensive spatial data on vegetation and wildlife habitat distribution, the authors identified strategic vegetation and fauna conservation foci for the 400 000 ha Fort Bliss military reservation in New Mexico and Texas relative to a 164 km radius ecological context region intersecting seven ecological zones and the predicted habitat distribution of 616 animal species. The authors set two specific criteria: (1) predicted area of a species' occurrence is <50% of the ecological context region; and (2) percentage of Fort Bliss intersecting the species' or vegetation community predicted areas in the ecological context region is >5% (Fort Bliss is 4.2% of the region). These criteria selected one vegetation class and 40 animal species. Further, these vegetation and animal foci were primarily located in two areas of Fort Bliss. Sensitivity analyses with other analytical radii corroborated the context radius used. Conservation of the two areas and associated taxa will maximize the contribution of Fort Bliss's conservation efforts in its ecological proximity. This relatively simple but information-rich process represents economical and defensible preliminary contextual analysis for detailed conservation planning. 相似文献
260.
Bruce Feldstein 《Disasters》1983,7(2):86-87
Accidents and sudden illness constitutes a major public health problem in many countries. Emergency medicine had developed as a vigorous new specialty in the U.S. and has fully integrated itself within the American medical and hospital system to provide improved emergency medical care. Emergency medicine plays a central role in disaster medical services, planning, and management and is the only specialty in American civilian medicine that includes disaster medicine as a primary field within its domain. Now that the basic framework of emergency medicine has been established, the American College of Emergency Physicians is implementing a nationwide training program on disaster planning and management for emergency physicians. 相似文献